[v4] Add objtool and orc support for LoongArch

[PATCH v4 8/8] LoongArch: Add ORC stack unwinder support

Posted by Tiezhu Yang 2 years, 2 months ago

The kernel CONFIG_UNWINDER_ORC option enables the ORC unwinder, which is
similar in concept to a DWARF unwinder. The difference is that the format
of the ORC data is much simpler than DWARF, which in turn allows the ORC
unwinder to be much simpler and faster.

The ORC data consists of unwind tables which are generated by objtool.
They contain out-of-band data which is used by the in-kernel ORC unwinder.
Objtool generates the ORC data by first doing compile-time stack metadata
validation (CONFIG_STACK_VALIDATION). After analyzing all the code paths
of a .o file, it determines information about the stack state at each
instruction address in the file and outputs that information to the
.orc_unwind and .orc_unwind_ip sections.

The per-object ORC sections are combined at link time and are sorted and
post-processed at boot time. The unwinder uses the resulting data to
correlate instruction addresses with their stack states at run time.

Most of the logic are similar with x86, in order to get ra info before ra
is saved into stack, add ra_reg and ra_offset into orc_entry. At the same
time, modify some arch-specific code to silence the objtool warnings.

Co-developed-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Co-developed-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 arch/loongarch/Kconfig                    |   2 +
 arch/loongarch/Kconfig.debug              |  11 +
 arch/loongarch/Makefile                   |  19 ++
 arch/loongarch/include/asm/Kbuild         |   2 +
 arch/loongarch/include/asm/bug.h          |   1 +
 arch/loongarch/include/asm/exception.h    |   2 +
 arch/loongarch/include/asm/module.h       |   7 +
 arch/loongarch/include/asm/orc_header.h   |  18 ++
 arch/loongarch/include/asm/orc_lookup.h   |  31 ++
 arch/loongarch/include/asm/orc_types.h    |  58 ++++
 arch/loongarch/include/asm/stackframe.h   |   3 +
 arch/loongarch/include/asm/unwind.h       |  19 +-
 arch/loongarch/include/asm/unwind_hints.h |  28 ++
 arch/loongarch/kernel/Makefile            |   4 +
 arch/loongarch/kernel/entry.S             |   5 +
 arch/loongarch/kernel/genex.S             |   4 +
 arch/loongarch/kernel/module.c            |  22 +-
 arch/loongarch/kernel/relocate_kernel.S   |   2 +
 arch/loongarch/kernel/setup.c             |   2 +
 arch/loongarch/kernel/stacktrace.c        |   1 +
 arch/loongarch/kernel/traps.c             |  42 ++-
 arch/loongarch/kernel/unwind_orc.c        | 513 ++++++++++++++++++++++++++++++
 arch/loongarch/kernel/vmlinux.lds.S       |   3 +
 arch/loongarch/lib/Makefile               |   2 +
 arch/loongarch/mm/tlb.c                   |  27 +-
 arch/loongarch/mm/tlbex.S                 |   9 +
 arch/loongarch/vdso/Makefile              |   1 +
 include/linux/compiler.h                  |   9 +
 scripts/Makefile                          |   7 +-
 29 files changed, 818 insertions(+), 36 deletions(-)
 create mode 100644 arch/loongarch/include/asm/orc_header.h
 create mode 100644 arch/loongarch/include/asm/orc_lookup.h
 create mode 100644 arch/loongarch/include/asm/orc_types.h
 create mode 100644 arch/loongarch/include/asm/unwind_hints.h
 create mode 100644 arch/loongarch/kernel/unwind_orc.c

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index e14396a..21ef3bb 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -131,6 +131,7 @@ config LOONGARCH
 	select HAVE_KRETPROBES
 	select HAVE_MOD_ARCH_SPECIFIC
 	select HAVE_NMI
+	select HAVE_OBJTOOL if AS_HAS_EXPLICIT_RELOCS
 	select HAVE_PCI
 	select HAVE_PERF_EVENTS
 	select HAVE_PERF_REGS
@@ -141,6 +142,7 @@ config LOONGARCH
 	select HAVE_SAMPLE_FTRACE_DIRECT
 	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
 	select HAVE_SETUP_PER_CPU_AREA if NUMA
+	select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
 	select HAVE_STACKPROTECTOR
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_TIF_NOHZ
diff --git a/arch/loongarch/Kconfig.debug b/arch/loongarch/Kconfig.debug
index 8d36aab..98d6063 100644
--- a/arch/loongarch/Kconfig.debug
+++ b/arch/loongarch/Kconfig.debug
@@ -26,4 +26,15 @@ config UNWINDER_PROLOGUE
 	  Some of the addresses it reports may be incorrect (but better than the
 	  Guess unwinder).
 
+config UNWINDER_ORC
+	bool "ORC unwinder"
+	select OBJTOOL
+	help
+	  This option enables the ORC (Oops Rewind Capability) unwinder for
+	  unwinding kernel stack traces.  It uses a custom data format which is
+	  a simplified version of the DWARF Call Frame Information standard.
+
+	  Enabling this option will increase the kernel's runtime memory usage
+	  by roughly 2-4MB, depending on your kernel config.
+
 endchoice
diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
index fb0fada..93ebdc3 100644
--- a/arch/loongarch/Makefile
+++ b/arch/loongarch/Makefile
@@ -25,6 +25,18 @@ endif
 32bit-emul		= elf32loongarch
 64bit-emul		= elf64loongarch
 
+ifdef CONFIG_UNWINDER_ORC
+orc_hash_h := arch/$(SRCARCH)/include/generated/asm/orc_hash.h
+orc_hash_sh := $(srctree)/scripts/orc_hash.sh
+targets += $(orc_hash_h)
+quiet_cmd_orc_hash = GEN     $@
+      cmd_orc_hash = mkdir -p $(dir $@); \
+		     $(CONFIG_SHELL) $(orc_hash_sh) < $< > $@
+$(orc_hash_h): $(srctree)/arch/loongarch/include/asm/orc_types.h $(orc_hash_sh) FORCE
+	$(call if_changed,orc_hash)
+archprepare: $(orc_hash_h)
+endif
+
 ifdef CONFIG_DYNAMIC_FTRACE
 KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
 CC_FLAGS_FTRACE := -fpatchable-function-entry=2
@@ -78,6 +90,13 @@ KBUILD_AFLAGS_MODULE		+= -Wa,-mla-global-with-abs
 KBUILD_CFLAGS_MODULE		+= -fplt -Wa,-mla-global-with-abs,-mla-local-with-abs
 endif
 
+KBUILD_AFLAGS			+= $(call cc-option,-mthin-add-sub) $(call cc-option,-Wa$(comma)-mthin-add-sub)
+KBUILD_CFLAGS			+= $(call cc-option,-mthin-add-sub) $(call cc-option,-Wa$(comma)-mthin-add-sub)
+
+ifdef CONFIG_OBJTOOL
+KBUILD_CFLAGS			+= -fno-optimize-sibling-calls -fno-jump-tables -falign-functions=4
+endif
+
 ifeq ($(CONFIG_RELOCATABLE),y)
 KBUILD_CFLAGS_KERNEL		+= -fPIE
 LDFLAGS_vmlinux			+= -static -pie --no-dynamic-linker -z notext
diff --git a/arch/loongarch/include/asm/Kbuild b/arch/loongarch/include/asm/Kbuild
index 93783fa..a97c0ed 100644
--- a/arch/loongarch/include/asm/Kbuild
+++ b/arch/loongarch/include/asm/Kbuild
@@ -1,4 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
+generated-y += orc_hash.h
+
 generic-y += dma-contiguous.h
 generic-y += mcs_spinlock.h
 generic-y += parport.h
diff --git a/arch/loongarch/include/asm/bug.h b/arch/loongarch/include/asm/bug.h
index d4ca3ba..0838887 100644
--- a/arch/loongarch/include/asm/bug.h
+++ b/arch/loongarch/include/asm/bug.h
@@ -44,6 +44,7 @@
 do {								\
 	instrumentation_begin();				\
 	__BUG_FLAGS(BUGFLAG_WARNING|(flags));			\
+	annotate_reachable();					\
 	instrumentation_end();					\
 } while (0)
 
diff --git a/arch/loongarch/include/asm/exception.h b/arch/loongarch/include/asm/exception.h
index af74a3f..c6d2073 100644
--- a/arch/loongarch/include/asm/exception.h
+++ b/arch/loongarch/include/asm/exception.h
@@ -6,6 +6,8 @@
 #include <asm/ptrace.h>
 #include <linux/kprobes.h>
 
+extern void *exception_table[];
+
 void show_registers(struct pt_regs *regs);
 
 asmlinkage void cache_parity_error(void);
diff --git a/arch/loongarch/include/asm/module.h b/arch/loongarch/include/asm/module.h
index 2ecd82b..f33f3fd 100644
--- a/arch/loongarch/include/asm/module.h
+++ b/arch/loongarch/include/asm/module.h
@@ -6,6 +6,7 @@
 #define _ASM_MODULE_H
 
 #include <asm/inst.h>
+#include <asm/orc_types.h>
 #include <asm-generic/module.h>
 
 #define RELA_STACK_DEPTH 16
@@ -21,6 +22,12 @@ struct mod_arch_specific {
 	struct mod_section plt;
 	struct mod_section plt_idx;
 
+#ifdef CONFIG_UNWINDER_ORC
+	unsigned int num_orcs;
+	int *orc_unwind_ip;
+	struct orc_entry *orc_unwind;
+#endif
+
 	/* For CONFIG_DYNAMIC_FTRACE */
 	struct plt_entry *ftrace_trampolines;
 };
diff --git a/arch/loongarch/include/asm/orc_header.h b/arch/loongarch/include/asm/orc_header.h
new file mode 100644
index 0000000..f9d509c
--- /dev/null
+++ b/arch/loongarch/include/asm/orc_header.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef _ORC_HEADER_H
+#define _ORC_HEADER_H
+
+#include <linux/types.h>
+#include <linux/compiler.h>
+#include <asm/orc_hash.h>
+
+/*
+ * The header is currently a 20-byte hash of the ORC entry definition; see
+ * scripts/orc_hash.sh.
+ */
+#define ORC_HEADER					\
+	__used __section(".orc_header") __aligned(4)	\
+	static const u8 orc_header[] = { ORC_HASH }
+
+#endif /* _ORC_HEADER_H */
diff --git a/arch/loongarch/include/asm/orc_lookup.h b/arch/loongarch/include/asm/orc_lookup.h
new file mode 100644
index 0000000..b02e635
--- /dev/null
+++ b/arch/loongarch/include/asm/orc_lookup.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _ORC_LOOKUP_H
+#define _ORC_LOOKUP_H
+
+/*
+ * This is a lookup table for speeding up access to the .orc_unwind table.
+ * Given an input address offset, the corresponding lookup table entry
+ * specifies a subset of the .orc_unwind table to search.
+ *
+ * Each block represents the end of the previous range and the start of the
+ * next range.  An extra block is added to give the last range an end.
+ *
+ * The block size should be a power of 2 to avoid a costly 'div' instruction.
+ *
+ * A block size of 256 was chosen because it roughly doubles unwinder
+ * performance while only adding ~5% to the ORC data footprint.
+ */
+#define LOOKUP_BLOCK_ORDER	8
+#define LOOKUP_BLOCK_SIZE	(1 << LOOKUP_BLOCK_ORDER)
+
+#ifndef LINKER_SCRIPT
+
+extern unsigned int orc_lookup[];
+extern unsigned int orc_lookup_end[];
+
+#define LOOKUP_START_IP		(unsigned long)_stext
+#define LOOKUP_STOP_IP		(unsigned long)_etext
+
+#endif /* LINKER_SCRIPT */
+
+#endif /* _ORC_LOOKUP_H */
diff --git a/arch/loongarch/include/asm/orc_types.h b/arch/loongarch/include/asm/orc_types.h
new file mode 100644
index 0000000..caf1f71
--- /dev/null
+++ b/arch/loongarch/include/asm/orc_types.h
@@ -0,0 +1,58 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _ORC_TYPES_H
+#define _ORC_TYPES_H
+
+#include <linux/types.h>
+
+/*
+ * The ORC_REG_* registers are base registers which are used to find other
+ * registers on the stack.
+ *
+ * ORC_REG_PREV_SP, also known as DWARF Call Frame Address (CFA), is the
+ * address of the previous frame: the caller's SP before it called the current
+ * function.
+ *
+ * ORC_REG_UNDEFINED means the corresponding register's value didn't change in
+ * the current frame.
+ *
+ * The most commonly used base registers are SP and FP -- which the previous SP
+ * is usually based on -- and PREV_SP and UNDEFINED -- which the previous FP is
+ * usually based on.
+ *
+ * The rest of the base registers are needed for special cases like entry code
+ * and GCC realigned stacks.
+ */
+#define ORC_REG_UNDEFINED		0
+#define ORC_REG_PREV_SP			1
+#define ORC_REG_SP			2
+#define ORC_REG_FP			3
+#define ORC_REG_MAX			4
+
+#define ORC_TYPE_UNDEFINED		0
+#define ORC_TYPE_END_OF_STACK		1
+#define ORC_TYPE_CALL			2
+#define ORC_TYPE_REGS			3
+#define ORC_TYPE_REGS_PARTIAL		4
+
+#ifndef __ASSEMBLY__
+/*
+ * This struct is more or less a vastly simplified version of the DWARF Call
+ * Frame Information standard.  It contains only the necessary parts of DWARF
+ * CFI, simplified for ease of access by the in-kernel unwinder.  It tells the
+ * unwinder how to find the previous SP and FP (and sometimes entry regs) on
+ * the stack for a given code address.  Each instance of the struct corresponds
+ * to one or more code locations.
+ */
+struct orc_entry {
+	s16		sp_offset;
+	s16		fp_offset;
+	s16		ra_offset;
+	unsigned int	sp_reg:4;
+	unsigned int	fp_reg:4;
+	unsigned int	ra_reg:4;
+	unsigned int	type:3;
+	unsigned int	signal:1;
+};
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ORC_TYPES_H */
diff --git a/arch/loongarch/include/asm/stackframe.h b/arch/loongarch/include/asm/stackframe.h
index 4fb1e64..45b507a 100644
--- a/arch/loongarch/include/asm/stackframe.h
+++ b/arch/loongarch/include/asm/stackframe.h
@@ -13,6 +13,7 @@
 #include <asm/asm-offsets.h>
 #include <asm/loongarch.h>
 #include <asm/thread_info.h>
+#include <asm/unwind_hints.h>
 
 /* Make the addition of cfi info a little easier. */
 	.macro cfi_rel_offset reg offset=0 docfi=0
@@ -162,6 +163,7 @@
 	li.w	t0, CSR_CRMD_WE
 	csrxchg	t0, t0, LOONGARCH_CSR_CRMD
 #endif
+	UNWIND_HINT_REGS
 	.endm
 
 	.macro	SAVE_ALL docfi=0
@@ -219,6 +221,7 @@
 
 	.macro	RESTORE_SP_AND_RET docfi=0
 	cfi_ld	sp, PT_R3, \docfi
+	UNWIND_HINT_FUNC
 	ertn
 	.endm
 
diff --git a/arch/loongarch/include/asm/unwind.h b/arch/loongarch/include/asm/unwind.h
index b9dce87..c7f52d4 100644
--- a/arch/loongarch/include/asm/unwind.h
+++ b/arch/loongarch/include/asm/unwind.h
@@ -16,6 +16,7 @@
 enum unwinder_type {
 	UNWINDER_GUESS,
 	UNWINDER_PROLOGUE,
+	UNWINDER_ORC,
 };
 
 struct unwind_state {
@@ -24,7 +25,7 @@ struct unwind_state {
 	struct task_struct *task;
 	bool first, error, reset;
 	int graph_idx;
-	unsigned long sp, pc, ra;
+	unsigned long sp, fp, pc, ra;
 };
 
 bool default_next_frame(struct unwind_state *state);
@@ -34,6 +35,14 @@ void unwind_start(struct unwind_state *state,
 bool unwind_next_frame(struct unwind_state *state);
 unsigned long unwind_get_return_address(struct unwind_state *state);
 
+#ifdef CONFIG_UNWINDER_ORC
+void unwind_init(void);
+void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size, void *orc, size_t orc_size);
+#else
+static inline void unwind_init(void) {}
+static inline void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size, void *orc, size_t orc_size) {}
+#endif
+
 static inline bool unwind_done(struct unwind_state *state)
 {
 	return state->stack_info.type == STACK_TYPE_UNKNOWN;
@@ -61,14 +70,17 @@ static __always_inline void __unwind_start(struct unwind_state *state,
 		state->sp = regs->regs[3];
 		state->pc = regs->csr_era;
 		state->ra = regs->regs[1];
+		state->fp = regs->regs[22];
 	} else if (task && task != current) {
 		state->sp = thread_saved_fp(task);
 		state->pc = thread_saved_ra(task);
 		state->ra = 0;
+		state->fp = 0;
 	} else {
 		state->sp = (unsigned long)__builtin_frame_address(0);
 		state->pc = (unsigned long)__builtin_return_address(0);
 		state->ra = 0;
+		state->fp = 0;
 	}
 	state->task = task;
 	get_stack_info(state->sp, state->task, &state->stack_info);
@@ -77,6 +89,9 @@ static __always_inline void __unwind_start(struct unwind_state *state,
 
 static __always_inline unsigned long __unwind_get_return_address(struct unwind_state *state)
 {
-	return unwind_done(state) ? 0 : state->pc;
+	if (unwind_done(state))
+		return 0;
+
+	return __kernel_text_address(state->pc) ? state->pc : 0;
 }
 #endif /* _ASM_UNWIND_H */
diff --git a/arch/loongarch/include/asm/unwind_hints.h b/arch/loongarch/include/asm/unwind_hints.h
new file mode 100644
index 0000000..82443fe
--- /dev/null
+++ b/arch/loongarch/include/asm/unwind_hints.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_LOONGARCH_UNWIND_HINTS_H
+#define _ASM_LOONGARCH_UNWIND_HINTS_H
+
+#include <linux/objtool.h>
+#include <asm/orc_types.h>
+
+#ifdef __ASSEMBLY__
+
+.macro UNWIND_HINT_UNDEFINED
+	UNWIND_HINT type=UNWIND_HINT_TYPE_UNDEFINED
+.endm
+
+.macro UNWIND_HINT_EMPTY
+	UNWIND_HINT sp_reg=ORC_REG_UNDEFINED type=UNWIND_HINT_TYPE_CALL
+.endm
+
+.macro UNWIND_HINT_REGS
+	UNWIND_HINT sp_reg=ORC_REG_SP type=UNWIND_HINT_TYPE_REGS
+.endm
+
+.macro UNWIND_HINT_FUNC
+	UNWIND_HINT sp_reg=ORC_REG_SP type=UNWIND_HINT_TYPE_CALL
+.endm
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_LOONGARCH_UNWIND_HINTS_H */
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index 4fcc168..ac47e11 100644
--- a/arch/loongarch/kernel/Makefile
+++ b/arch/loongarch/kernel/Makefile
@@ -3,6 +3,8 @@
 # Makefile for the Linux/LoongArch kernel.
 #
 
+OBJECT_FILES_NON_STANDARD_head.o := y
+
 extra-y		:= vmlinux.lds
 
 obj-y		+= head.o cpu-probe.o cacheinfo.o env.o setup.o entry.o genex.o \
@@ -21,6 +23,7 @@ obj-$(CONFIG_ARCH_STRICT_ALIGN)	+= unaligned.o
 
 CFLAGS_module.o		+= $(call cc-option,-Wno-override-init,)
 CFLAGS_syscall.o	+= $(call cc-option,-Wno-override-init,)
+CFLAGS_traps.o		+= $(call cc-option,-Wno-override-init,)
 CFLAGS_perf_event.o	+= $(call cc-option,-Wno-override-init,)
 
 ifdef CONFIG_FUNCTION_TRACER
@@ -62,6 +65,7 @@ obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o
 
 obj-$(CONFIG_UNWINDER_GUESS)	+= unwind_guess.o
 obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o
+obj-$(CONFIG_UNWINDER_ORC)	+= unwind_orc.o
 
 obj-$(CONFIG_PERF_EVENTS)	+= perf_event.o perf_regs.o
 obj-$(CONFIG_HAVE_HW_BREAKPOINT)	+= hw_breakpoint.o
diff --git a/arch/loongarch/kernel/entry.S b/arch/loongarch/kernel/entry.S
index 1ec8e4c..48e7e34 100644
--- a/arch/loongarch/kernel/entry.S
+++ b/arch/loongarch/kernel/entry.S
@@ -14,11 +14,13 @@
 #include <asm/regdef.h>
 #include <asm/stackframe.h>
 #include <asm/thread_info.h>
+#include <asm/unwind_hints.h>
 
 	.text
 	.cfi_sections	.debug_frame
 	.align	5
 SYM_CODE_START(handle_syscall)
+	UNWIND_HINT_UNDEFINED
 	csrrd		t0, PERCPU_BASE_KS
 	la.pcrel	t1, kernelsp
 	add.d		t1, t1, t0
@@ -57,6 +59,7 @@ SYM_CODE_START(handle_syscall)
 	cfi_st		fp, PT_R22
 
 	SAVE_STATIC
+	UNWIND_HINT_REGS
 
 #ifdef CONFIG_KGDB
 	li.w		t1, CSR_CRMD_WE
@@ -75,6 +78,7 @@ SYM_CODE_END(handle_syscall)
 _ASM_NOKPROBE(handle_syscall)
 
 SYM_CODE_START(ret_from_fork)
+	UNWIND_HINT_REGS
 	bl		schedule_tail		# a0 = struct task_struct *prev
 	move		a0, sp
 	bl 		syscall_exit_to_user_mode
@@ -84,6 +88,7 @@ SYM_CODE_START(ret_from_fork)
 SYM_CODE_END(ret_from_fork)
 
 SYM_CODE_START(ret_from_kernel_thread)
+	UNWIND_HINT_REGS
 	bl		schedule_tail		# a0 = struct task_struct *prev
 	move		a0, s1
 	jirl		ra, s0, 0
diff --git a/arch/loongarch/kernel/genex.S b/arch/loongarch/kernel/genex.S
index 2bb3aa2..3f18e3b 100644
--- a/arch/loongarch/kernel/genex.S
+++ b/arch/loongarch/kernel/genex.S
@@ -32,6 +32,7 @@ SYM_FUNC_START(__arch_cpu_idle)
 SYM_FUNC_END(__arch_cpu_idle)
 
 SYM_CODE_START(handle_vint)
+	UNWIND_HINT_UNDEFINED
 	BACKUP_T0T1
 	SAVE_ALL
 	la_abs	t1, __arch_cpu_idle
@@ -49,6 +50,7 @@ SYM_CODE_START(handle_vint)
 SYM_CODE_END(handle_vint)
 
 SYM_CODE_START(except_vec_cex)
+	UNWIND_HINT_UNDEFINED
 	b	cache_parity_error
 SYM_CODE_END(except_vec_cex)
 
@@ -67,6 +69,7 @@ SYM_CODE_END(except_vec_cex)
 	.macro	BUILD_HANDLER exception handler prep
 	.align	5
 	SYM_CODE_START(handle_\exception)
+	UNWIND_HINT_UNDEFINED
 	666:
 	BACKUP_T0T1
 	SAVE_ALL
@@ -94,6 +97,7 @@ SYM_CODE_END(except_vec_cex)
 	BUILD_HANDLER reserved reserved none	/* others */
 
 SYM_CODE_START(handle_sys)
+	UNWIND_HINT_UNDEFINED
 	la_abs	t0, handle_syscall
 	jr	t0
 SYM_CODE_END(handle_sys)
diff --git a/arch/loongarch/kernel/module.c b/arch/loongarch/kernel/module.c
index b13b285..c7d0338 100644
--- a/arch/loongarch/kernel/module.c
+++ b/arch/loongarch/kernel/module.c
@@ -20,6 +20,7 @@
 #include <linux/kernel.h>
 #include <asm/alternative.h>
 #include <asm/inst.h>
+#include <asm/unwind.h>
 
 static int rela_stack_push(s64 stack_value, s64 *rela_stack, size_t *rela_stack_top)
 {
@@ -515,15 +516,28 @@ static void module_init_ftrace_plt(const Elf_Ehdr *hdr,
 int module_finalize(const Elf_Ehdr *hdr,
 		    const Elf_Shdr *sechdrs, struct module *mod)
 {
-	const Elf_Shdr *s, *se;
 	const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
+	const Elf_Shdr *s, *alt = NULL, *orc = NULL, *orc_ip = NULL, *ftrace = NULL;
 
-	for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++) {
+	for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
 		if (!strcmp(".altinstructions", secstrs + s->sh_name))
-			apply_alternatives((void *)s->sh_addr, (void *)s->sh_addr + s->sh_size);
+			alt = s;
+		if (!strcmp(".orc_unwind", secstrs + s->sh_name))
+			orc = s;
+		if (!strcmp(".orc_unwind_ip", secstrs + s->sh_name))
+			orc_ip = s;
 		if (!strcmp(".ftrace_trampoline", secstrs + s->sh_name))
-			module_init_ftrace_plt(hdr, s, mod);
+			ftrace = s;
 	}
 
+	if (alt)
+		apply_alternatives((void *)alt->sh_addr, (void *)alt->sh_addr + alt->sh_size);
+
+	if (orc && orc_ip)
+		unwind_module_init(mod, (void *)orc_ip->sh_addr, orc_ip->sh_size, (void *)orc->sh_addr, orc->sh_size);
+
+	if (ftrace)
+		module_init_ftrace_plt(hdr, ftrace, mod);
+
 	return 0;
 }
diff --git a/arch/loongarch/kernel/relocate_kernel.S b/arch/loongarch/kernel/relocate_kernel.S
index f49f6b0..bcc191d 100644
--- a/arch/loongarch/kernel/relocate_kernel.S
+++ b/arch/loongarch/kernel/relocate_kernel.S
@@ -15,6 +15,7 @@
 #include <asm/addrspace.h>
 
 SYM_CODE_START(relocate_new_kernel)
+	UNWIND_HINT_UNDEFINED
 	/*
 	 * a0: EFI boot flag for the new kernel
 	 * a1: Command line pointer for the new kernel
@@ -90,6 +91,7 @@ SYM_CODE_END(relocate_new_kernel)
  * then start at the entry point from LOONGARCH_IOCSR_MBUF0.
  */
 SYM_CODE_START(kexec_smp_wait)
+	UNWIND_HINT_UNDEFINED
 1:	li.w		t0, 0x100			/* wait for init loop */
 2:	addi.w		t0, t0, -1			/* limit mailbox access */
 	bnez		t0, 2b
diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
index aed65915..613f04d 100644
--- a/arch/loongarch/kernel/setup.c
+++ b/arch/loongarch/kernel/setup.c
@@ -48,6 +48,7 @@
 #include <asm/sections.h>
 #include <asm/setup.h>
 #include <asm/time.h>
+#include <asm/unwind.h>
 
 #define SMBIOS_BIOSSIZE_OFFSET		0x09
 #define SMBIOS_BIOSEXTERN_OFFSET	0x13
@@ -606,6 +607,7 @@ static void __init prefill_possible_map(void)
 void __init setup_arch(char **cmdline_p)
 {
 	cpu_probe();
+	unwind_init();
 
 	init_environ();
 	efi_init();
diff --git a/arch/loongarch/kernel/stacktrace.c b/arch/loongarch/kernel/stacktrace.c
index 92270f1..9848d42 100644
--- a/arch/loongarch/kernel/stacktrace.c
+++ b/arch/loongarch/kernel/stacktrace.c
@@ -29,6 +29,7 @@ void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
 			regs->csr_era = thread_saved_ra(task);
 		}
 		regs->regs[1] = 0;
+		regs->regs[22] = 0;
 	}
 
 	for (unwind_start(&state, task, regs);
diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
index aebfc37..f9f4eb0 100644
--- a/arch/loongarch/kernel/traps.c
+++ b/arch/loongarch/kernel/traps.c
@@ -53,6 +53,32 @@
 
 #include "access-helper.h"
 
+void *exception_table[EXCCODE_INT_START] = {
+	[0 ... EXCCODE_INT_START - 1] = handle_reserved,
+
+	[EXCCODE_TLBI]		= handle_tlb_load,
+	[EXCCODE_TLBL]		= handle_tlb_load,
+	[EXCCODE_TLBS]		= handle_tlb_store,
+	[EXCCODE_TLBM]		= handle_tlb_modify,
+	[EXCCODE_TLBNR]		= handle_tlb_protect,
+	[EXCCODE_TLBNX]		= handle_tlb_protect,
+	[EXCCODE_TLBPE]		= handle_tlb_protect,
+	[EXCCODE_ADE]		= handle_ade,
+	[EXCCODE_ALE]		= handle_ale,
+	[EXCCODE_BCE]		= handle_bce,
+	[EXCCODE_SYS]		= handle_sys,
+	[EXCCODE_BP]		= handle_bp,
+	[EXCCODE_INE]		= handle_ri,
+	[EXCCODE_IPE]		= handle_ri,
+	[EXCCODE_FPDIS]		= handle_fpu,
+	[EXCCODE_LSXDIS]	= handle_lsx,
+	[EXCCODE_LASXDIS]	= handle_lasx,
+	[EXCCODE_FPE]		= handle_fpe,
+	[EXCCODE_WATCH]		= handle_watch,
+	[EXCCODE_BTDIS]		= handle_lbt,
+};
+EXPORT_SYMBOL_GPL(exception_table);
+
 static void show_backtrace(struct task_struct *task, const struct pt_regs *regs,
 			   const char *loglvl, bool user)
 {
@@ -1150,19 +1176,9 @@ void __init trap_init(void)
 	for (i = EXCCODE_INT_START; i <= EXCCODE_INT_END; i++)
 		set_handler(i * VECSIZE, handle_vint, VECSIZE);
 
-	set_handler(EXCCODE_ADE * VECSIZE, handle_ade, VECSIZE);
-	set_handler(EXCCODE_ALE * VECSIZE, handle_ale, VECSIZE);
-	set_handler(EXCCODE_BCE * VECSIZE, handle_bce, VECSIZE);
-	set_handler(EXCCODE_SYS * VECSIZE, handle_sys, VECSIZE);
-	set_handler(EXCCODE_BP * VECSIZE, handle_bp, VECSIZE);
-	set_handler(EXCCODE_INE * VECSIZE, handle_ri, VECSIZE);
-	set_handler(EXCCODE_IPE * VECSIZE, handle_ri, VECSIZE);
-	set_handler(EXCCODE_FPDIS * VECSIZE, handle_fpu, VECSIZE);
-	set_handler(EXCCODE_LSXDIS * VECSIZE, handle_lsx, VECSIZE);
-	set_handler(EXCCODE_LASXDIS * VECSIZE, handle_lasx, VECSIZE);
-	set_handler(EXCCODE_FPE * VECSIZE, handle_fpe, VECSIZE);
-	set_handler(EXCCODE_BTDIS * VECSIZE, handle_lbt, VECSIZE);
-	set_handler(EXCCODE_WATCH * VECSIZE, handle_watch, VECSIZE);
+	/* Set exception vector handler */
+	for (i = EXCCODE_ADE; i <= EXCCODE_BTDIS; i++)
+		set_handler(i * VECSIZE, exception_table[i], VECSIZE);
 
 	cache_error_setup();
 
diff --git a/arch/loongarch/kernel/unwind_orc.c b/arch/loongarch/kernel/unwind_orc.c
new file mode 100644
index 0000000..9be5cead
--- /dev/null
+++ b/arch/loongarch/kernel/unwind_orc.c
@@ -0,0 +1,513 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/objtool.h>
+#include <linux/module.h>
+#include <linux/sort.h>
+#include <asm/exception.h>
+#include <asm/orc_header.h>
+#include <asm/orc_lookup.h>
+#include <asm/orc_types.h>
+#include <asm/ptrace.h>
+#include <asm/setup.h>
+#include <asm/stacktrace.h>
+#include <asm/tlb.h>
+#include <asm/unwind.h>
+
+ORC_HEADER;
+
+#define orc_warn(fmt, ...) \
+	printk_deferred_once(KERN_WARNING "WARNING: " fmt, ##__VA_ARGS__)
+
+extern int __start_orc_unwind_ip[];
+extern int __stop_orc_unwind_ip[];
+extern struct orc_entry __start_orc_unwind[];
+extern struct orc_entry __stop_orc_unwind[];
+
+static bool orc_init __ro_after_init;
+static unsigned int lookup_num_blocks __ro_after_init;
+
+/* Fake frame pointer entry -- used as a fallback for generated code */
+static struct orc_entry orc_fp_entry = {
+	.sp_reg		= ORC_REG_FP,
+	.sp_offset	= 16,
+	.fp_reg		= ORC_REG_PREV_SP,
+	.fp_offset	= -16,
+	.ra_reg		= ORC_REG_PREV_SP,
+	.ra_offset	= -8,
+	.type		= ORC_TYPE_CALL
+};
+
+/*
+ * If we crash with IP==0, the last successfully executed instruction
+ * was probably an indirect function call with a NULL function pointer,
+ * and we don't have unwind information for NULL.
+ * This hardcoded ORC entry for IP==0 allows us to unwind from a NULL function
+ * pointer into its parent and then continue normally from there.
+ */
+static struct orc_entry orc_null_entry = {
+	.sp_reg		= ORC_REG_SP,
+	.sp_offset	= sizeof(long),
+	.fp_reg		= ORC_REG_UNDEFINED,
+	.type		= ORC_TYPE_CALL
+};
+
+static inline unsigned long orc_ip(const int *ip)
+{
+	return (unsigned long)ip + *ip;
+}
+
+static struct orc_entry *__orc_find(int *ip_table, struct orc_entry *u_table,
+				    unsigned int num_entries, unsigned long ip)
+{
+	int *first = ip_table;
+	int *mid = first, *found = first;
+	int *last = ip_table + num_entries - 1;
+
+	if (!num_entries)
+		return NULL;
+
+	/*
+	 * Do a binary range search to find the rightmost duplicate of a given
+	 * starting address.  Some entries are section terminators which are
+	 * "weak" entries for ensuring there are no gaps.  They should be
+	 * ignored when they conflict with a real entry.
+	 */
+	while (first <= last) {
+		mid = first + ((last - first) / 2);
+
+		if (orc_ip(mid) <= ip) {
+			found = mid;
+			first = mid + 1;
+		} else
+			last = mid - 1;
+	}
+
+	return u_table + (found - ip_table);
+}
+
+#ifdef CONFIG_MODULES
+static struct orc_entry *orc_module_find(unsigned long ip)
+{
+	struct module *mod;
+
+	mod = __module_address(ip);
+	if (!mod || !mod->arch.orc_unwind || !mod->arch.orc_unwind_ip)
+		return NULL;
+
+	return __orc_find(mod->arch.orc_unwind_ip, mod->arch.orc_unwind, mod->arch.num_orcs, ip);
+}
+#else
+static struct orc_entry *orc_module_find(unsigned long ip)
+{
+	return NULL;
+}
+#endif
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+static struct orc_entry *orc_find(unsigned long ip);
+
+/*
+ * Ftrace dynamic trampolines do not have orc entries of their own.
+ * But they are copies of the ftrace entries that are static and
+ * defined in ftrace_*.S, which do have orc entries.
+ *
+ * If the unwinder comes across a ftrace trampoline, then find the
+ * ftrace function that was used to create it, and use that ftrace
+ * function's orc entry, as the placement of the return code in
+ * the stack will be identical.
+ */
+static struct orc_entry *orc_ftrace_find(unsigned long ip)
+{
+	struct ftrace_ops *ops;
+	unsigned long tramp_addr, offset;
+
+	ops = ftrace_ops_trampoline(ip);
+	if (!ops)
+		return NULL;
+
+	/* Set tramp_addr to the start of the code copied by the trampoline */
+	if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)
+		tramp_addr = (unsigned long)ftrace_regs_caller;
+	else
+		tramp_addr = (unsigned long)ftrace_caller;
+
+	/* Now place tramp_addr to the location within the trampoline ip is at */
+	offset = ip - ops->trampoline;
+	tramp_addr += offset;
+
+	/* Prevent unlikely recursion */
+	if (ip == tramp_addr)
+		return NULL;
+
+	return orc_find(tramp_addr);
+}
+#else
+static struct orc_entry *orc_ftrace_find(unsigned long ip)
+{
+	return NULL;
+}
+#endif
+
+static struct orc_entry *orc_find(unsigned long ip)
+{
+	static struct orc_entry *orc;
+
+	if (ip == 0)
+		return &orc_null_entry;
+
+	/* For non-init vmlinux addresses, use the fast lookup table: */
+	if (ip >= LOOKUP_START_IP && ip < LOOKUP_STOP_IP) {
+		unsigned int idx, start, stop;
+
+		idx = (ip - LOOKUP_START_IP) / LOOKUP_BLOCK_SIZE;
+
+		if (unlikely((idx >= lookup_num_blocks-1))) {
+			orc_warn("WARNING: bad lookup idx: idx=%u num=%u ip=%pB\n",
+				 idx, lookup_num_blocks, (void *)ip);
+			return NULL;
+		}
+
+		start = orc_lookup[idx];
+		stop = orc_lookup[idx + 1] + 1;
+
+		if (unlikely((__start_orc_unwind + start >= __stop_orc_unwind) ||
+			     (__start_orc_unwind + stop > __stop_orc_unwind))) {
+			orc_warn("WARNING: bad lookup value: idx=%u num=%u start=%u stop=%u ip=%pB\n",
+				 idx, lookup_num_blocks, start, stop, (void *)ip);
+			return NULL;
+		}
+
+		return __orc_find(__start_orc_unwind_ip + start,
+				  __start_orc_unwind + start, stop - start, ip);
+	}
+
+	/* vmlinux .init slow lookup: */
+	if (is_kernel_inittext(ip))
+		return __orc_find(__start_orc_unwind_ip, __start_orc_unwind,
+				  __stop_orc_unwind_ip - __start_orc_unwind_ip, ip);
+
+	/* Module lookup: */
+	orc = orc_module_find(ip);
+	if (orc)
+		return orc;
+
+	return orc_ftrace_find(ip);
+}
+
+#ifdef CONFIG_MODULES
+
+static DEFINE_MUTEX(sort_mutex);
+static int *cur_orc_ip_table = __start_orc_unwind_ip;
+static struct orc_entry *cur_orc_table = __start_orc_unwind;
+
+static void orc_sort_swap(void *_a, void *_b, int size)
+{
+	int delta = _b - _a;
+	int *a = _a, *b = _b, tmp;
+	struct orc_entry *orc_a, *orc_b;
+
+	/* Swap the .orc_unwind_ip entries: */
+	tmp = *a;
+	*a = *b + delta;
+	*b = tmp - delta;
+
+	/* Swap the corresponding .orc_unwind entries: */
+	orc_a = cur_orc_table + (a - cur_orc_ip_table);
+	orc_b = cur_orc_table + (b - cur_orc_ip_table);
+	swap(*orc_a, *orc_b);
+}
+
+static int orc_sort_cmp(const void *_a, const void *_b)
+{
+	const int *a = _a, *b = _b;
+	unsigned long a_val = orc_ip(a);
+	unsigned long b_val = orc_ip(b);
+	struct orc_entry *orc_a;
+
+	if (a_val > b_val)
+		return 1;
+	if (a_val < b_val)
+		return -1;
+
+	/*
+	 * The "weak" section terminator entries need to always be first
+	 * to ensure the lookup code skips them in favor of real entries.
+	 * These terminator entries exist to handle any gaps created by
+	 * whitelisted .o files which didn't get objtool generation.
+	 */
+	orc_a = cur_orc_table + (a - cur_orc_ip_table);
+
+	return orc_a->type == ORC_TYPE_UNDEFINED ? -1 : 1;
+}
+
+void unwind_module_init(struct module *mod, void *_orc_ip, size_t orc_ip_size,
+			void *_orc, size_t orc_size)
+{
+	int *orc_ip = _orc_ip;
+	struct orc_entry *orc = _orc;
+	unsigned int num_entries = orc_ip_size / sizeof(int);
+
+	WARN_ON_ONCE(orc_ip_size % sizeof(int) != 0 ||
+		     orc_size % sizeof(*orc) != 0 ||
+		     num_entries != orc_size / sizeof(*orc));
+
+	/*
+	 * The 'cur_orc_*' globals allow the orc_sort_swap() callback to
+	 * associate an .orc_unwind_ip table entry with its corresponding
+	 * .orc_unwind entry so they can both be swapped.
+	 */
+	mutex_lock(&sort_mutex);
+	cur_orc_ip_table = orc_ip;
+	cur_orc_table = orc;
+	sort(orc_ip, num_entries, sizeof(int), orc_sort_cmp, orc_sort_swap);
+	mutex_unlock(&sort_mutex);
+
+	mod->arch.orc_unwind_ip = orc_ip;
+	mod->arch.orc_unwind = orc;
+	mod->arch.num_orcs = num_entries;
+}
+#endif
+
+void __init unwind_init(void)
+{
+	int i;
+	size_t orc_size = (void *)__stop_orc_unwind - (void *)__start_orc_unwind;
+	size_t orc_ip_size = (void *)__stop_orc_unwind_ip - (void *)__start_orc_unwind_ip;
+	size_t num_entries = orc_ip_size / sizeof(int);
+	struct orc_entry *orc;
+
+	if (!num_entries || orc_ip_size % sizeof(int) != 0 ||
+	    orc_size % sizeof(struct orc_entry) != 0 ||
+	    num_entries != orc_size / sizeof(struct orc_entry)) {
+		orc_warn("WARNING: Bad or missing .orc_unwind table.  Disabling unwinder.\n");
+		return;
+	}
+
+	/*
+	 * Note, the orc_unwind and orc_unwind_ip tables were already
+	 * sorted at build time via the 'sorttable' tool.
+	 * It's ready for binary search straight away, no need to sort it.
+	 */
+
+	/* Initialize the fast lookup table: */
+	lookup_num_blocks = orc_lookup_end - orc_lookup;
+	for (i = 0; i < lookup_num_blocks-1; i++) {
+		orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind,
+				 num_entries, LOOKUP_START_IP + (LOOKUP_BLOCK_SIZE * i));
+		if (!orc) {
+			orc_warn("WARNING: Corrupt .orc_unwind table.  Disabling unwinder.\n");
+			return;
+		}
+
+		orc_lookup[i] = orc - __start_orc_unwind;
+	}
+
+	/* Initialize the ending block: */
+	orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind, num_entries, LOOKUP_STOP_IP);
+	if (!orc) {
+		orc_warn("WARNING: Corrupt .orc_unwind table.  Disabling unwinder.\n");
+		return;
+	}
+	orc_lookup[lookup_num_blocks-1] = orc - __start_orc_unwind;
+
+	orc_init = true;
+}
+
+static inline bool on_stack(struct stack_info *info, unsigned long addr, size_t len)
+{
+	unsigned long begin = info->begin;
+	unsigned long end   = info->end;
+
+	return (info->type != STACK_TYPE_UNKNOWN &&
+		addr >= begin && addr < end && addr + len > begin && addr + len <= end);
+}
+
+static bool stack_access_ok(struct unwind_state *state, unsigned long addr, size_t len)
+{
+	struct stack_info *info = &state->stack_info;
+
+	if (on_stack(info, addr, len))
+		return true;
+
+	return (get_stack_info(addr, state->task, info) == 0);
+}
+
+unsigned long unwind_get_return_address(struct unwind_state *state)
+{
+	return __unwind_get_return_address(state);
+}
+EXPORT_SYMBOL_GPL(unwind_get_return_address);
+
+void unwind_start(struct unwind_state *state, struct task_struct *task,
+		    struct pt_regs *regs)
+{
+	__unwind_start(state, task, regs);
+	state->type = UNWINDER_ORC;
+	if (!unwind_done(state) && !__kernel_text_address(state->pc))
+		unwind_next_frame(state);
+}
+EXPORT_SYMBOL_GPL(unwind_start);
+
+static bool is_entry_func(unsigned long addr)
+{
+	extern u32 kernel_entry;
+	extern u32 kernel_entry_end;
+
+	return addr >= (unsigned long)&kernel_entry && addr < (unsigned long)&kernel_entry_end;
+}
+
+static inline unsigned long bt_address(unsigned long ra)
+{
+	extern unsigned long eentry;
+
+	if (__kernel_text_address(ra))
+		return ra;
+
+	if (__module_text_address(ra))
+		return ra;
+
+	if (ra >= eentry && ra < eentry +  EXCCODE_INT_END * VECSIZE) {
+		unsigned long func;
+		unsigned long type = (ra - eentry) / VECSIZE;
+		unsigned long offset = (ra - eentry) % VECSIZE;
+
+		switch (type) {
+		case 0 ... EXCCODE_INT_START - 1:
+			func = (unsigned long)exception_table[type];
+			break;
+		case EXCCODE_INT_START ... EXCCODE_INT_END:
+			func = (unsigned long)handle_vint;
+			break;
+		default:
+			func = (unsigned long)handle_reserved;
+			break;
+		}
+
+		return func + offset;
+	}
+
+	return ra;
+}
+
+bool unwind_next_frame(struct unwind_state *state)
+{
+	unsigned long *p, pc;
+	struct pt_regs *regs;
+	struct orc_entry *orc;
+	struct stack_info *info = &state->stack_info;
+
+	if (unwind_done(state))
+		return false;
+
+	/* Don't let modules unload while we're reading their ORC data. */
+	preempt_disable();
+
+	if (is_entry_func(state->pc))
+		goto end;
+
+	orc = orc_find(state->pc);
+	if (!orc) {
+		orc = &orc_fp_entry;
+		state->error = true;
+	}
+
+	switch (orc->sp_reg) {
+	case ORC_REG_SP:
+		state->sp = state->sp + orc->sp_offset;
+		break;
+	case ORC_REG_FP:
+		state->sp = state->fp;
+		break;
+	default:
+		orc_warn("unknown SP base reg %d at %pB\n", orc->sp_reg, (void *)state->pc);
+		goto err;
+	}
+
+	switch (orc->fp_reg) {
+	case ORC_REG_PREV_SP:
+		p = (unsigned long *)(state->sp + orc->fp_offset);
+		if (!stack_access_ok(state, (unsigned long)p, sizeof(unsigned long)))
+			goto err;
+
+		state->fp = *p;
+		break;
+	case ORC_REG_UNDEFINED:
+		/* Nothing. */
+		break;
+	default:
+		orc_warn("unknown FP base reg %d at %pB\n", orc->fp_reg, (void *)state->pc);
+		goto err;
+	}
+
+	switch (orc->type) {
+	case ORC_TYPE_CALL:
+		if (orc->ra_reg == ORC_REG_PREV_SP) {
+			p = (unsigned long *)(state->sp + orc->ra_offset);
+			if (!stack_access_ok(state, (unsigned long)p, sizeof(unsigned long)))
+				goto err;
+
+			pc = unwind_graph_addr(state, *p, state->sp);
+			pc -= LOONGARCH_INSN_SIZE;
+		} else if (orc->ra_reg == ORC_REG_UNDEFINED) {
+			if (!state->ra || state->ra == state->pc)
+				goto err;
+
+			pc = unwind_graph_addr(state, state->ra, state->sp);
+			pc -=  LOONGARCH_INSN_SIZE;
+			state->ra = 0;
+		} else {
+			orc_warn("unknown ra base reg %d at %pB\n", orc->ra_reg, (void *)state->pc);
+			goto err;
+		}
+		break;
+	case ORC_TYPE_REGS:
+		if (state->stack_info.type == STACK_TYPE_IRQ && state->sp == info->end)
+			regs = (struct pt_regs *)info->next_sp;
+		else
+			regs = (struct pt_regs *)state->sp;
+
+		if (!stack_access_ok(state, (unsigned long)regs, sizeof(*regs)))
+			goto err;
+
+		if ((info->end == (unsigned long)regs + sizeof(*regs)) &&
+		    !regs->regs[3] && !regs->regs[1])
+			goto end;
+
+		if (user_mode(regs))
+			goto end;
+
+		pc = regs->csr_era;
+		if (!__kernel_text_address(pc))
+			goto err;
+
+		state->sp = regs->regs[3];
+		state->ra = regs->regs[1];
+		state->fp = regs->regs[22];
+		get_stack_info(state->sp, state->task, info);
+
+		break;
+	default:
+		orc_warn("unknown .orc_unwind entry type %d at %pB\n", orc->type, (void *)state->pc);
+		goto err;
+	}
+
+	state->pc = bt_address(pc);
+	if (!state->pc) {
+		pr_err("cannot find unwind pc at %pK\n", (void *)pc);
+		goto err;
+	}
+
+	if (!__kernel_text_address(state->pc))
+		goto err;
+
+	preempt_enable();
+	return true;
+
+err:
+	state->error = true;
+
+end:
+	preempt_enable();
+	state->stack_info.type = STACK_TYPE_UNKNOWN;
+	return false;
+}
+EXPORT_SYMBOL_GPL(unwind_next_frame);
diff --git a/arch/loongarch/kernel/vmlinux.lds.S b/arch/loongarch/kernel/vmlinux.lds.S
index bb2ec86..eaa7a91 100644
--- a/arch/loongarch/kernel/vmlinux.lds.S
+++ b/arch/loongarch/kernel/vmlinux.lds.S
@@ -2,6 +2,7 @@
 #include <linux/sizes.h>
 #include <asm/asm-offsets.h>
 #include <asm/thread_info.h>
+#include <asm/orc_lookup.h>
 
 #define PAGE_SIZE _PAGE_SIZE
 #define RO_EXCEPTION_TABLE_ALIGN	4
@@ -122,6 +123,8 @@ SECTIONS
 	}
 #endif
 
+	ORC_UNWIND_TABLE
+
 	.sdata : {
 		*(.sdata)
 	}
diff --git a/arch/loongarch/lib/Makefile b/arch/loongarch/lib/Makefile
index a77bf160..e3023d9 100644
--- a/arch/loongarch/lib/Makefile
+++ b/arch/loongarch/lib/Makefile
@@ -3,6 +3,8 @@
 # Makefile for LoongArch-specific library files.
 #
 
+OBJECT_FILES_NON_STANDARD := y
+
 lib-y	+= delay.o memset.o memcpy.o memmove.o \
 	   clear_user.o copy_user.o csum.o dump_tlb.o unaligned.o
 
diff --git a/arch/loongarch/mm/tlb.c b/arch/loongarch/mm/tlb.c
index 2c0a411..f01172a 100644
--- a/arch/loongarch/mm/tlb.c
+++ b/arch/loongarch/mm/tlb.c
@@ -9,8 +9,9 @@
 #include <linux/hugetlb.h>
 #include <linux/export.h>
 
-#include <asm/cpu.h>
 #include <asm/bootinfo.h>
+#include <asm/cpu.h>
+#include <asm/exception.h>
 #include <asm/mmu_context.h>
 #include <asm/pgtable.h>
 #include <asm/tlb.h>
@@ -266,24 +267,20 @@ static void setup_tlb_handler(int cpu)
 	setup_ptwalker();
 	local_flush_tlb_all();
 
+	if (cpu_has_ptw) {
+		exception_table[EXCCODE_TLBI] = handle_tlb_load_ptw;
+		exception_table[EXCCODE_TLBL] = handle_tlb_load_ptw;
+		exception_table[EXCCODE_TLBS] = handle_tlb_store_ptw;
+		exception_table[EXCCODE_TLBM] = handle_tlb_modify_ptw;
+	}
+
 	/* The tlb handlers are generated only once */
 	if (cpu == 0) {
 		memcpy((void *)tlbrentry, handle_tlb_refill, 0x80);
 		local_flush_icache_range(tlbrentry, tlbrentry + 0x80);
-		if (!cpu_has_ptw) {
-			set_handler(EXCCODE_TLBI * VECSIZE, handle_tlb_load, VECSIZE);
-			set_handler(EXCCODE_TLBL * VECSIZE, handle_tlb_load, VECSIZE);
-			set_handler(EXCCODE_TLBS * VECSIZE, handle_tlb_store, VECSIZE);
-			set_handler(EXCCODE_TLBM * VECSIZE, handle_tlb_modify, VECSIZE);
-		} else {
-			set_handler(EXCCODE_TLBI * VECSIZE, handle_tlb_load_ptw, VECSIZE);
-			set_handler(EXCCODE_TLBL * VECSIZE, handle_tlb_load_ptw, VECSIZE);
-			set_handler(EXCCODE_TLBS * VECSIZE, handle_tlb_store_ptw, VECSIZE);
-			set_handler(EXCCODE_TLBM * VECSIZE, handle_tlb_modify_ptw, VECSIZE);
-		}
-		set_handler(EXCCODE_TLBNR * VECSIZE, handle_tlb_protect, VECSIZE);
-		set_handler(EXCCODE_TLBNX * VECSIZE, handle_tlb_protect, VECSIZE);
-		set_handler(EXCCODE_TLBPE * VECSIZE, handle_tlb_protect, VECSIZE);
+
+		for (int i = EXCCODE_TLBL; i <= EXCCODE_TLBPE; i++)
+			set_handler(i * VECSIZE, exception_table[i], VECSIZE);
 	}
 #ifdef CONFIG_NUMA
 	else {
diff --git a/arch/loongarch/mm/tlbex.S b/arch/loongarch/mm/tlbex.S
index d5d682f..a44387b 100644
--- a/arch/loongarch/mm/tlbex.S
+++ b/arch/loongarch/mm/tlbex.S
@@ -18,6 +18,7 @@
 
 	.macro tlb_do_page_fault, write
 	SYM_CODE_START(tlb_do_page_fault_\write)
+	UNWIND_HINT_UNDEFINED
 	SAVE_ALL
 	csrrd		a2, LOONGARCH_CSR_BADV
 	move		a0, sp
@@ -32,6 +33,7 @@
 	tlb_do_page_fault 1
 
 SYM_CODE_START(handle_tlb_protect)
+	UNWIND_HINT_UNDEFINED
 	BACKUP_T0T1
 	SAVE_ALL
 	move		a0, sp
@@ -44,6 +46,7 @@ SYM_CODE_START(handle_tlb_protect)
 SYM_CODE_END(handle_tlb_protect)
 
 SYM_CODE_START(handle_tlb_load)
+	UNWIND_HINT_UNDEFINED
 	csrwr		t0, EXCEPTION_KS0
 	csrwr		t1, EXCEPTION_KS1
 	csrwr		ra, EXCEPTION_KS2
@@ -190,6 +193,7 @@ nopage_tlb_load:
 SYM_CODE_END(handle_tlb_load)
 
 SYM_CODE_START(handle_tlb_load_ptw)
+	UNWIND_HINT_UNDEFINED
 	csrwr		t0, LOONGARCH_CSR_KS0
 	csrwr		t1, LOONGARCH_CSR_KS1
 	la_abs		t0, tlb_do_page_fault_0
@@ -197,6 +201,7 @@ SYM_CODE_START(handle_tlb_load_ptw)
 SYM_CODE_END(handle_tlb_load_ptw)
 
 SYM_CODE_START(handle_tlb_store)
+	UNWIND_HINT_UNDEFINED
 	csrwr		t0, EXCEPTION_KS0
 	csrwr		t1, EXCEPTION_KS1
 	csrwr		ra, EXCEPTION_KS2
@@ -346,6 +351,7 @@ nopage_tlb_store:
 SYM_CODE_END(handle_tlb_store)
 
 SYM_CODE_START(handle_tlb_store_ptw)
+	UNWIND_HINT_UNDEFINED
 	csrwr		t0, LOONGARCH_CSR_KS0
 	csrwr		t1, LOONGARCH_CSR_KS1
 	la_abs		t0, tlb_do_page_fault_1
@@ -353,6 +359,7 @@ SYM_CODE_START(handle_tlb_store_ptw)
 SYM_CODE_END(handle_tlb_store_ptw)
 
 SYM_CODE_START(handle_tlb_modify)
+	UNWIND_HINT_UNDEFINED
 	csrwr		t0, EXCEPTION_KS0
 	csrwr		t1, EXCEPTION_KS1
 	csrwr		ra, EXCEPTION_KS2
@@ -500,6 +507,7 @@ nopage_tlb_modify:
 SYM_CODE_END(handle_tlb_modify)
 
 SYM_CODE_START(handle_tlb_modify_ptw)
+	UNWIND_HINT_UNDEFINED
 	csrwr		t0, LOONGARCH_CSR_KS0
 	csrwr		t1, LOONGARCH_CSR_KS1
 	la_abs		t0, tlb_do_page_fault_1
@@ -507,6 +515,7 @@ SYM_CODE_START(handle_tlb_modify_ptw)
 SYM_CODE_END(handle_tlb_modify_ptw)
 
 SYM_CODE_START(handle_tlb_refill)
+	UNWIND_HINT_UNDEFINED
 	csrwr		t0, LOONGARCH_CSR_TLBRSAVE
 	csrrd		t0, LOONGARCH_CSR_PGD
 	lddir		t0, t0, 3
diff --git a/arch/loongarch/vdso/Makefile b/arch/loongarch/vdso/Makefile
index 5c97d1463..997f41c 100644
--- a/arch/loongarch/vdso/Makefile
+++ b/arch/loongarch/vdso/Makefile
@@ -3,6 +3,7 @@
 
 KASAN_SANITIZE := n
 KCOV_INSTRUMENT := n
+OBJECT_FILES_NON_STANDARD := y
 
 # Include the generic Makefile to check the built vdso.
 include $(srctree)/lib/vdso/Makefile
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index d7779a1..df29ddb 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -116,6 +116,14 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
  */
 #define __stringify_label(n) #n
 
+#define __annotate_reachable(c) ({					\
+	asm volatile(__stringify_label(c) ":\n\t"			\
+			".pushsection .discard.reachable\n\t"		\
+			".long " __stringify_label(c) "b - .\n\t"	\
+			".popsection\n\t");				\
+})
+#define annotate_reachable() __annotate_reachable(__COUNTER__)
+
 #define __annotate_unreachable(c) ({					\
 	asm volatile(__stringify_label(c) ":\n\t"			\
 		     ".pushsection .discard.unreachable\n\t"		\
@@ -128,6 +136,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 #define __annotate_jump_table __section(".rodata..c_jump_table")
 
 #else /* !CONFIG_OBJTOOL */
+#define annotate_reachable()
 #define annotate_unreachable()
 #define __annotate_jump_table
 #endif /* CONFIG_OBJTOOL */
diff --git a/scripts/Makefile b/scripts/Makefile
index 576cf64..e4cca53 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -31,9 +31,12 @@ HOSTLDLIBS_sign-file = $(shell $(HOSTPKG_CONFIG) --libs libcrypto 2> /dev/null |
 
 ifdef CONFIG_UNWINDER_ORC
 ifeq ($(ARCH),x86_64)
-ARCH := x86
+SRCARCH := x86
 endif
-HOSTCFLAGS_sorttable.o += -I$(srctree)/tools/arch/x86/include
+ifeq ($(ARCH),loongarch)
+SRCARCH := loongarch
+endif
+HOSTCFLAGS_sorttable.o += -I$(srctree)/tools/arch/$(SRCARCH)/include
 HOSTCFLAGS_sorttable.o += -DUNWINDER_ORC_ENABLED
 endif
 
-- 
2.1.0

Re: [PATCH v4 8/8] LoongArch: Add ORC stack unwinder support

Posted by Huacai Chen 2 years, 2 months ago

v3 works in most cases, v4 cannot work completely (stop at show_stack), why?

[   61.412528] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.6.0-rc7+ #1157
[   61.419017] Hardware name: Loongson
Loongson-3A5000-7A1000-1w-CRB/Loongson-LS3A5000-7A1000-1w-CRB, BIOS
vUDK2018-LoongArch-V2.0.0-prebeta9 10/21/2022
[   61.432328] pc 9000000002ad14c0 ra 9000000003d759c8 tp
90000001001e4000 sp 90000001001e7e40
[   61.440629] a0 0000000000000005 a1 0000000000000001 a2
90000001001e4000 a3 9000000003d7cdf4
[   61.448930] a4 900000010bb1f940 a5 0000000000000000 a6
0000000000000000 a7 000000000000239c
[   61.457229] t0 0000000000000000 t1 0000000000022c34 t2
4000000000000000 t3 0000000000000001
[   61.465530] t4 4000000000000000 t5 00000000000000b0 t6
0000000000000004 t7 0000000000000000
[   61.473830] t8 0000000000000000 u0 0000000000000004 s9
9000000004caa940 s0 0000000000000004
[   61.482130] s1 900000000427aa38 s2 0000000000000004 s3
0000000000000000 s4 900000000427b000
[   61.490429] s5 00000000000f0000 s6 0000000000000004 s7
000000000000039b s8 0000000000000004
[   61.498730]    ra: 9000000003d759c8 arch_cpu_idle+0x1c/0x34
[   61.504270]   ERA: 9000000002ad14c0 __arch_cpu_idle+0x20/0x24
[   61.509979]  CRMD: 000000b0 (PLV0 -IE -DA +PG DACF=CC DACM=CC -WE)
[   61.516134]  PRMD: 00000004 (PPLV0 +PIE -PWE)
[   61.520465]  EUEN: 00000000 (-FPE -SXE -ASXE -BTE)
[   61.525230]  ECFG: 00071c1c (LIE=2-4,10-12 VS=7)
[   61.529820] ESTAT: 00001000 [INT] (IS=12 ECode=0 EsubCode=0)
[   61.535446]  PRID: 0014c010 (Loongson-64bit, Loongson-3A5000)
[   61.541154] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.6.0-rc7+ #1157
[   61.547640] Hardware name: Loongson
Loongson-3A5000-7A1000-1w-CRB/Loongson-LS3A5000-7A1000-1w-CRB, BIOS
vUDK2018-LoongArch-V2.0.0-prebeta9 10/21/2022
[   61.560952] Stack : 0000000000000000 ffffffffffffffff
9000000003d73848 90000001001e4000
[   61.568914]         900000010006fca0 0000000000000000
900000010006fca8 9000000004108e10
[   61.576875]         9000000004363958 9000000004363950
900000010006fbc0 0000000000000001
[   61.584837]         0000000000000001 83899b396b7be748
00000000069f0000 9000000100177080
[   61.592798]         0000000000000000 372d303030354133
0000000000000001 0000000000000003
[   61.600759]         6f4c203a656d616e 0000000000085b38
00000000069f0000 9000000004caa940
[   61.608721]         9000000004279000 9000000004108e10
0000000000000004 0000000000000000
[   61.616682]         90000000042833f0 90000001001e7d00
0000000000000000 0000000000000001
[   61.624644]         0000000000000004 900000010006fbf0
9000000002ad3808 00007fffec50f0f0
[   61.632605]         00000000000000b0 0000000000000004
0000000000000000 0000000000071c1c
[   61.640566]         ...
[   61.642993] Call Trace:
[   61.642995] [<9000000002ad3808>] show_stack+0x40/0x17c

Huacai

On Mon, Oct 23, 2023 at 4:11 PM Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
>
> The kernel CONFIG_UNWINDER_ORC option enables the ORC unwinder, which is
> similar in concept to a DWARF unwinder. The difference is that the format
> of the ORC data is much simpler than DWARF, which in turn allows the ORC
> unwinder to be much simpler and faster.
>
> The ORC data consists of unwind tables which are generated by objtool.
> They contain out-of-band data which is used by the in-kernel ORC unwinder.
> Objtool generates the ORC data by first doing compile-time stack metadata
> validation (CONFIG_STACK_VALIDATION). After analyzing all the code paths
> of a .o file, it determines information about the stack state at each
> instruction address in the file and outputs that information to the
> .orc_unwind and .orc_unwind_ip sections.
>
> The per-object ORC sections are combined at link time and are sorted and
> post-processed at boot time. The unwinder uses the resulting data to
> correlate instruction addresses with their stack states at run time.
>
> Most of the logic are similar with x86, in order to get ra info before ra
> is saved into stack, add ra_reg and ra_offset into orc_entry. At the same
> time, modify some arch-specific code to silence the objtool warnings.
>
> Co-developed-by: Jinyang He <hejinyang@loongson.cn>
> Signed-off-by: Jinyang He <hejinyang@loongson.cn>
> Co-developed-by: Youling Tang <tangyouling@loongson.cn>
> Signed-off-by: Youling Tang <tangyouling@loongson.cn>
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> ---
>  arch/loongarch/Kconfig                    |   2 +
>  arch/loongarch/Kconfig.debug              |  11 +
>  arch/loongarch/Makefile                   |  19 ++
>  arch/loongarch/include/asm/Kbuild         |   2 +
>  arch/loongarch/include/asm/bug.h          |   1 +
>  arch/loongarch/include/asm/exception.h    |   2 +
>  arch/loongarch/include/asm/module.h       |   7 +
>  arch/loongarch/include/asm/orc_header.h   |  18 ++
>  arch/loongarch/include/asm/orc_lookup.h   |  31 ++
>  arch/loongarch/include/asm/orc_types.h    |  58 ++++
>  arch/loongarch/include/asm/stackframe.h   |   3 +
>  arch/loongarch/include/asm/unwind.h       |  19 +-
>  arch/loongarch/include/asm/unwind_hints.h |  28 ++
>  arch/loongarch/kernel/Makefile            |   4 +
>  arch/loongarch/kernel/entry.S             |   5 +
>  arch/loongarch/kernel/genex.S             |   4 +
>  arch/loongarch/kernel/module.c            |  22 +-
>  arch/loongarch/kernel/relocate_kernel.S   |   2 +
>  arch/loongarch/kernel/setup.c             |   2 +
>  arch/loongarch/kernel/stacktrace.c        |   1 +
>  arch/loongarch/kernel/traps.c             |  42 ++-
>  arch/loongarch/kernel/unwind_orc.c        | 513 ++++++++++++++++++++++++++++++
>  arch/loongarch/kernel/vmlinux.lds.S       |   3 +
>  arch/loongarch/lib/Makefile               |   2 +
>  arch/loongarch/mm/tlb.c                   |  27 +-
>  arch/loongarch/mm/tlbex.S                 |   9 +
>  arch/loongarch/vdso/Makefile              |   1 +
>  include/linux/compiler.h                  |   9 +
>  scripts/Makefile                          |   7 +-
>  29 files changed, 818 insertions(+), 36 deletions(-)
>  create mode 100644 arch/loongarch/include/asm/orc_header.h
>  create mode 100644 arch/loongarch/include/asm/orc_lookup.h
>  create mode 100644 arch/loongarch/include/asm/orc_types.h
>  create mode 100644 arch/loongarch/include/asm/unwind_hints.h
>  create mode 100644 arch/loongarch/kernel/unwind_orc.c
>
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> index e14396a..21ef3bb 100644
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -131,6 +131,7 @@ config LOONGARCH
>         select HAVE_KRETPROBES
>         select HAVE_MOD_ARCH_SPECIFIC
>         select HAVE_NMI
> +       select HAVE_OBJTOOL if AS_HAS_EXPLICIT_RELOCS
>         select HAVE_PCI
>         select HAVE_PERF_EVENTS
>         select HAVE_PERF_REGS
> @@ -141,6 +142,7 @@ config LOONGARCH
>         select HAVE_SAMPLE_FTRACE_DIRECT
>         select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
>         select HAVE_SETUP_PER_CPU_AREA if NUMA
> +       select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
>         select HAVE_STACKPROTECTOR
>         select HAVE_SYSCALL_TRACEPOINTS
>         select HAVE_TIF_NOHZ
> diff --git a/arch/loongarch/Kconfig.debug b/arch/loongarch/Kconfig.debug
> index 8d36aab..98d6063 100644
> --- a/arch/loongarch/Kconfig.debug
> +++ b/arch/loongarch/Kconfig.debug
> @@ -26,4 +26,15 @@ config UNWINDER_PROLOGUE
>           Some of the addresses it reports may be incorrect (but better than the
>           Guess unwinder).
>
> +config UNWINDER_ORC
> +       bool "ORC unwinder"
> +       select OBJTOOL
> +       help
> +         This option enables the ORC (Oops Rewind Capability) unwinder for
> +         unwinding kernel stack traces.  It uses a custom data format which is
> +         a simplified version of the DWARF Call Frame Information standard.
> +
> +         Enabling this option will increase the kernel's runtime memory usage
> +         by roughly 2-4MB, depending on your kernel config.
> +
>  endchoice
> diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
> index fb0fada..93ebdc3 100644
> --- a/arch/loongarch/Makefile
> +++ b/arch/loongarch/Makefile
> @@ -25,6 +25,18 @@ endif
>  32bit-emul             = elf32loongarch
>  64bit-emul             = elf64loongarch
>
> +ifdef CONFIG_UNWINDER_ORC
> +orc_hash_h := arch/$(SRCARCH)/include/generated/asm/orc_hash.h
> +orc_hash_sh := $(srctree)/scripts/orc_hash.sh
> +targets += $(orc_hash_h)
> +quiet_cmd_orc_hash = GEN     $@
> +      cmd_orc_hash = mkdir -p $(dir $@); \
> +                    $(CONFIG_SHELL) $(orc_hash_sh) < $< > $@
> +$(orc_hash_h): $(srctree)/arch/loongarch/include/asm/orc_types.h $(orc_hash_sh) FORCE
> +       $(call if_changed,orc_hash)
> +archprepare: $(orc_hash_h)
> +endif
> +
>  ifdef CONFIG_DYNAMIC_FTRACE
>  KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
>  CC_FLAGS_FTRACE := -fpatchable-function-entry=2
> @@ -78,6 +90,13 @@ KBUILD_AFLAGS_MODULE         += -Wa,-mla-global-with-abs
>  KBUILD_CFLAGS_MODULE           += -fplt -Wa,-mla-global-with-abs,-mla-local-with-abs
>  endif
>
> +KBUILD_AFLAGS                  += $(call cc-option,-mthin-add-sub) $(call cc-option,-Wa$(comma)-mthin-add-sub)
> +KBUILD_CFLAGS                  += $(call cc-option,-mthin-add-sub) $(call cc-option,-Wa$(comma)-mthin-add-sub)
> +
> +ifdef CONFIG_OBJTOOL
> +KBUILD_CFLAGS                  += -fno-optimize-sibling-calls -fno-jump-tables -falign-functions=4
> +endif
> +
>  ifeq ($(CONFIG_RELOCATABLE),y)
>  KBUILD_CFLAGS_KERNEL           += -fPIE
>  LDFLAGS_vmlinux                        += -static -pie --no-dynamic-linker -z notext
> diff --git a/arch/loongarch/include/asm/Kbuild b/arch/loongarch/include/asm/Kbuild
> index 93783fa..a97c0ed 100644
> --- a/arch/loongarch/include/asm/Kbuild
> +++ b/arch/loongarch/include/asm/Kbuild
> @@ -1,4 +1,6 @@
>  # SPDX-License-Identifier: GPL-2.0
> +generated-y += orc_hash.h
> +
>  generic-y += dma-contiguous.h
>  generic-y += mcs_spinlock.h
>  generic-y += parport.h
> diff --git a/arch/loongarch/include/asm/bug.h b/arch/loongarch/include/asm/bug.h
> index d4ca3ba..0838887 100644
> --- a/arch/loongarch/include/asm/bug.h
> +++ b/arch/loongarch/include/asm/bug.h
> @@ -44,6 +44,7 @@
>  do {                                                           \
>         instrumentation_begin();                                \
>         __BUG_FLAGS(BUGFLAG_WARNING|(flags));                   \
> +       annotate_reachable();                                   \
>         instrumentation_end();                                  \
>  } while (0)
>
> diff --git a/arch/loongarch/include/asm/exception.h b/arch/loongarch/include/asm/exception.h
> index af74a3f..c6d2073 100644
> --- a/arch/loongarch/include/asm/exception.h
> +++ b/arch/loongarch/include/asm/exception.h
> @@ -6,6 +6,8 @@
>  #include <asm/ptrace.h>
>  #include <linux/kprobes.h>
>
> +extern void *exception_table[];
> +
>  void show_registers(struct pt_regs *regs);
>
>  asmlinkage void cache_parity_error(void);
> diff --git a/arch/loongarch/include/asm/module.h b/arch/loongarch/include/asm/module.h
> index 2ecd82b..f33f3fd 100644
> --- a/arch/loongarch/include/asm/module.h
> +++ b/arch/loongarch/include/asm/module.h
> @@ -6,6 +6,7 @@
>  #define _ASM_MODULE_H
>
>  #include <asm/inst.h>
> +#include <asm/orc_types.h>
>  #include <asm-generic/module.h>
>
>  #define RELA_STACK_DEPTH 16
> @@ -21,6 +22,12 @@ struct mod_arch_specific {
>         struct mod_section plt;
>         struct mod_section plt_idx;
>
> +#ifdef CONFIG_UNWINDER_ORC
> +       unsigned int num_orcs;
> +       int *orc_unwind_ip;
> +       struct orc_entry *orc_unwind;
> +#endif
> +
>         /* For CONFIG_DYNAMIC_FTRACE */
>         struct plt_entry *ftrace_trampolines;
>  };
> diff --git a/arch/loongarch/include/asm/orc_header.h b/arch/loongarch/include/asm/orc_header.h
> new file mode 100644
> index 0000000..f9d509c
> --- /dev/null
> +++ b/arch/loongarch/include/asm/orc_header.h
> @@ -0,0 +1,18 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +
> +#ifndef _ORC_HEADER_H
> +#define _ORC_HEADER_H
> +
> +#include <linux/types.h>
> +#include <linux/compiler.h>
> +#include <asm/orc_hash.h>
> +
> +/*
> + * The header is currently a 20-byte hash of the ORC entry definition; see
> + * scripts/orc_hash.sh.
> + */
> +#define ORC_HEADER                                     \
> +       __used __section(".orc_header") __aligned(4)    \
> +       static const u8 orc_header[] = { ORC_HASH }
> +
> +#endif /* _ORC_HEADER_H */
> diff --git a/arch/loongarch/include/asm/orc_lookup.h b/arch/loongarch/include/asm/orc_lookup.h
> new file mode 100644
> index 0000000..b02e635
> --- /dev/null
> +++ b/arch/loongarch/include/asm/orc_lookup.h
> @@ -0,0 +1,31 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +#ifndef _ORC_LOOKUP_H
> +#define _ORC_LOOKUP_H
> +
> +/*
> + * This is a lookup table for speeding up access to the .orc_unwind table.
> + * Given an input address offset, the corresponding lookup table entry
> + * specifies a subset of the .orc_unwind table to search.
> + *
> + * Each block represents the end of the previous range and the start of the
> + * next range.  An extra block is added to give the last range an end.
> + *
> + * The block size should be a power of 2 to avoid a costly 'div' instruction.
> + *
> + * A block size of 256 was chosen because it roughly doubles unwinder
> + * performance while only adding ~5% to the ORC data footprint.
> + */
> +#define LOOKUP_BLOCK_ORDER     8
> +#define LOOKUP_BLOCK_SIZE      (1 << LOOKUP_BLOCK_ORDER)
> +
> +#ifndef LINKER_SCRIPT
> +
> +extern unsigned int orc_lookup[];
> +extern unsigned int orc_lookup_end[];
> +
> +#define LOOKUP_START_IP                (unsigned long)_stext
> +#define LOOKUP_STOP_IP         (unsigned long)_etext
> +
> +#endif /* LINKER_SCRIPT */
> +
> +#endif /* _ORC_LOOKUP_H */
> diff --git a/arch/loongarch/include/asm/orc_types.h b/arch/loongarch/include/asm/orc_types.h
> new file mode 100644
> index 0000000..caf1f71
> --- /dev/null
> +++ b/arch/loongarch/include/asm/orc_types.h
> @@ -0,0 +1,58 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +#ifndef _ORC_TYPES_H
> +#define _ORC_TYPES_H
> +
> +#include <linux/types.h>
> +
> +/*
> + * The ORC_REG_* registers are base registers which are used to find other
> + * registers on the stack.
> + *
> + * ORC_REG_PREV_SP, also known as DWARF Call Frame Address (CFA), is the
> + * address of the previous frame: the caller's SP before it called the current
> + * function.
> + *
> + * ORC_REG_UNDEFINED means the corresponding register's value didn't change in
> + * the current frame.
> + *
> + * The most commonly used base registers are SP and FP -- which the previous SP
> + * is usually based on -- and PREV_SP and UNDEFINED -- which the previous FP is
> + * usually based on.
> + *
> + * The rest of the base registers are needed for special cases like entry code
> + * and GCC realigned stacks.
> + */
> +#define ORC_REG_UNDEFINED              0
> +#define ORC_REG_PREV_SP                        1
> +#define ORC_REG_SP                     2
> +#define ORC_REG_FP                     3
> +#define ORC_REG_MAX                    4
> +
> +#define ORC_TYPE_UNDEFINED             0
> +#define ORC_TYPE_END_OF_STACK          1
> +#define ORC_TYPE_CALL                  2
> +#define ORC_TYPE_REGS                  3
> +#define ORC_TYPE_REGS_PARTIAL          4
> +
> +#ifndef __ASSEMBLY__
> +/*
> + * This struct is more or less a vastly simplified version of the DWARF Call
> + * Frame Information standard.  It contains only the necessary parts of DWARF
> + * CFI, simplified for ease of access by the in-kernel unwinder.  It tells the
> + * unwinder how to find the previous SP and FP (and sometimes entry regs) on
> + * the stack for a given code address.  Each instance of the struct corresponds
> + * to one or more code locations.
> + */
> +struct orc_entry {
> +       s16             sp_offset;
> +       s16             fp_offset;
> +       s16             ra_offset;
> +       unsigned int    sp_reg:4;
> +       unsigned int    fp_reg:4;
> +       unsigned int    ra_reg:4;
> +       unsigned int    type:3;
> +       unsigned int    signal:1;
> +};
> +#endif /* __ASSEMBLY__ */
> +
> +#endif /* _ORC_TYPES_H */
> diff --git a/arch/loongarch/include/asm/stackframe.h b/arch/loongarch/include/asm/stackframe.h
> index 4fb1e64..45b507a 100644
> --- a/arch/loongarch/include/asm/stackframe.h
> +++ b/arch/loongarch/include/asm/stackframe.h
> @@ -13,6 +13,7 @@
>  #include <asm/asm-offsets.h>
>  #include <asm/loongarch.h>
>  #include <asm/thread_info.h>
> +#include <asm/unwind_hints.h>
>
>  /* Make the addition of cfi info a little easier. */
>         .macro cfi_rel_offset reg offset=0 docfi=0
> @@ -162,6 +163,7 @@
>         li.w    t0, CSR_CRMD_WE
>         csrxchg t0, t0, LOONGARCH_CSR_CRMD
>  #endif
> +       UNWIND_HINT_REGS
>         .endm
>
>         .macro  SAVE_ALL docfi=0
> @@ -219,6 +221,7 @@
>
>         .macro  RESTORE_SP_AND_RET docfi=0
>         cfi_ld  sp, PT_R3, \docfi
> +       UNWIND_HINT_FUNC
>         ertn
>         .endm
>
> diff --git a/arch/loongarch/include/asm/unwind.h b/arch/loongarch/include/asm/unwind.h
> index b9dce87..c7f52d4 100644
> --- a/arch/loongarch/include/asm/unwind.h
> +++ b/arch/loongarch/include/asm/unwind.h
> @@ -16,6 +16,7 @@
>  enum unwinder_type {
>         UNWINDER_GUESS,
>         UNWINDER_PROLOGUE,
> +       UNWINDER_ORC,
>  };
>
>  struct unwind_state {
> @@ -24,7 +25,7 @@ struct unwind_state {
>         struct task_struct *task;
>         bool first, error, reset;
>         int graph_idx;
> -       unsigned long sp, pc, ra;
> +       unsigned long sp, fp, pc, ra;
>  };
>
>  bool default_next_frame(struct unwind_state *state);
> @@ -34,6 +35,14 @@ void unwind_start(struct unwind_state *state,
>  bool unwind_next_frame(struct unwind_state *state);
>  unsigned long unwind_get_return_address(struct unwind_state *state);
>
> +#ifdef CONFIG_UNWINDER_ORC
> +void unwind_init(void);
> +void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size, void *orc, size_t orc_size);
> +#else
> +static inline void unwind_init(void) {}
> +static inline void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size, void *orc, size_t orc_size) {}
> +#endif
> +
>  static inline bool unwind_done(struct unwind_state *state)
>  {
>         return state->stack_info.type == STACK_TYPE_UNKNOWN;
> @@ -61,14 +70,17 @@ static __always_inline void __unwind_start(struct unwind_state *state,
>                 state->sp = regs->regs[3];
>                 state->pc = regs->csr_era;
>                 state->ra = regs->regs[1];
> +               state->fp = regs->regs[22];
>         } else if (task && task != current) {
>                 state->sp = thread_saved_fp(task);
>                 state->pc = thread_saved_ra(task);
>                 state->ra = 0;
> +               state->fp = 0;
>         } else {
>                 state->sp = (unsigned long)__builtin_frame_address(0);
>                 state->pc = (unsigned long)__builtin_return_address(0);
>                 state->ra = 0;
> +               state->fp = 0;
>         }
>         state->task = task;
>         get_stack_info(state->sp, state->task, &state->stack_info);
> @@ -77,6 +89,9 @@ static __always_inline void __unwind_start(struct unwind_state *state,
>
>  static __always_inline unsigned long __unwind_get_return_address(struct unwind_state *state)
>  {
> -       return unwind_done(state) ? 0 : state->pc;
> +       if (unwind_done(state))
> +               return 0;
> +
> +       return __kernel_text_address(state->pc) ? state->pc : 0;
>  }
>  #endif /* _ASM_UNWIND_H */
> diff --git a/arch/loongarch/include/asm/unwind_hints.h b/arch/loongarch/include/asm/unwind_hints.h
> new file mode 100644
> index 0000000..82443fe
> --- /dev/null
> +++ b/arch/loongarch/include/asm/unwind_hints.h
> @@ -0,0 +1,28 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_LOONGARCH_UNWIND_HINTS_H
> +#define _ASM_LOONGARCH_UNWIND_HINTS_H
> +
> +#include <linux/objtool.h>
> +#include <asm/orc_types.h>
> +
> +#ifdef __ASSEMBLY__
> +
> +.macro UNWIND_HINT_UNDEFINED
> +       UNWIND_HINT type=UNWIND_HINT_TYPE_UNDEFINED
> +.endm
> +
> +.macro UNWIND_HINT_EMPTY
> +       UNWIND_HINT sp_reg=ORC_REG_UNDEFINED type=UNWIND_HINT_TYPE_CALL
> +.endm
> +
> +.macro UNWIND_HINT_REGS
> +       UNWIND_HINT sp_reg=ORC_REG_SP type=UNWIND_HINT_TYPE_REGS
> +.endm
> +
> +.macro UNWIND_HINT_FUNC
> +       UNWIND_HINT sp_reg=ORC_REG_SP type=UNWIND_HINT_TYPE_CALL
> +.endm
> +
> +#endif /* __ASSEMBLY__ */
> +
> +#endif /* _ASM_LOONGARCH_UNWIND_HINTS_H */
> diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
> index 4fcc168..ac47e11 100644
> --- a/arch/loongarch/kernel/Makefile
> +++ b/arch/loongarch/kernel/Makefile
> @@ -3,6 +3,8 @@
>  # Makefile for the Linux/LoongArch kernel.
>  #
>
> +OBJECT_FILES_NON_STANDARD_head.o := y
> +
>  extra-y                := vmlinux.lds
>
>  obj-y          += head.o cpu-probe.o cacheinfo.o env.o setup.o entry.o genex.o \
> @@ -21,6 +23,7 @@ obj-$(CONFIG_ARCH_STRICT_ALIGN)       += unaligned.o
>
>  CFLAGS_module.o                += $(call cc-option,-Wno-override-init,)
>  CFLAGS_syscall.o       += $(call cc-option,-Wno-override-init,)
> +CFLAGS_traps.o         += $(call cc-option,-Wno-override-init,)
>  CFLAGS_perf_event.o    += $(call cc-option,-Wno-override-init,)
>
>  ifdef CONFIG_FUNCTION_TRACER
> @@ -62,6 +65,7 @@ obj-$(CONFIG_CRASH_DUMP)      += crash_dump.o
>
>  obj-$(CONFIG_UNWINDER_GUESS)   += unwind_guess.o
>  obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o
> +obj-$(CONFIG_UNWINDER_ORC)     += unwind_orc.o
>
>  obj-$(CONFIG_PERF_EVENTS)      += perf_event.o perf_regs.o
>  obj-$(CONFIG_HAVE_HW_BREAKPOINT)       += hw_breakpoint.o
> diff --git a/arch/loongarch/kernel/entry.S b/arch/loongarch/kernel/entry.S
> index 1ec8e4c..48e7e34 100644
> --- a/arch/loongarch/kernel/entry.S
> +++ b/arch/loongarch/kernel/entry.S
> @@ -14,11 +14,13 @@
>  #include <asm/regdef.h>
>  #include <asm/stackframe.h>
>  #include <asm/thread_info.h>
> +#include <asm/unwind_hints.h>
>
>         .text
>         .cfi_sections   .debug_frame
>         .align  5
>  SYM_CODE_START(handle_syscall)
> +       UNWIND_HINT_UNDEFINED
>         csrrd           t0, PERCPU_BASE_KS
>         la.pcrel        t1, kernelsp
>         add.d           t1, t1, t0
> @@ -57,6 +59,7 @@ SYM_CODE_START(handle_syscall)
>         cfi_st          fp, PT_R22
>
>         SAVE_STATIC
> +       UNWIND_HINT_REGS
>
>  #ifdef CONFIG_KGDB
>         li.w            t1, CSR_CRMD_WE
> @@ -75,6 +78,7 @@ SYM_CODE_END(handle_syscall)
>  _ASM_NOKPROBE(handle_syscall)
>
>  SYM_CODE_START(ret_from_fork)
> +       UNWIND_HINT_REGS
>         bl              schedule_tail           # a0 = struct task_struct *prev
>         move            a0, sp
>         bl              syscall_exit_to_user_mode
> @@ -84,6 +88,7 @@ SYM_CODE_START(ret_from_fork)
>  SYM_CODE_END(ret_from_fork)
>
>  SYM_CODE_START(ret_from_kernel_thread)
> +       UNWIND_HINT_REGS
>         bl              schedule_tail           # a0 = struct task_struct *prev
>         move            a0, s1
>         jirl            ra, s0, 0
> diff --git a/arch/loongarch/kernel/genex.S b/arch/loongarch/kernel/genex.S
> index 2bb3aa2..3f18e3b 100644
> --- a/arch/loongarch/kernel/genex.S
> +++ b/arch/loongarch/kernel/genex.S
> @@ -32,6 +32,7 @@ SYM_FUNC_START(__arch_cpu_idle)
>  SYM_FUNC_END(__arch_cpu_idle)
>
>  SYM_CODE_START(handle_vint)
> +       UNWIND_HINT_UNDEFINED
>         BACKUP_T0T1
>         SAVE_ALL
>         la_abs  t1, __arch_cpu_idle
> @@ -49,6 +50,7 @@ SYM_CODE_START(handle_vint)
>  SYM_CODE_END(handle_vint)
>
>  SYM_CODE_START(except_vec_cex)
> +       UNWIND_HINT_UNDEFINED
>         b       cache_parity_error
>  SYM_CODE_END(except_vec_cex)
>
> @@ -67,6 +69,7 @@ SYM_CODE_END(except_vec_cex)
>         .macro  BUILD_HANDLER exception handler prep
>         .align  5
>         SYM_CODE_START(handle_\exception)
> +       UNWIND_HINT_UNDEFINED
>         666:
>         BACKUP_T0T1
>         SAVE_ALL
> @@ -94,6 +97,7 @@ SYM_CODE_END(except_vec_cex)
>         BUILD_HANDLER reserved reserved none    /* others */
>
>  SYM_CODE_START(handle_sys)
> +       UNWIND_HINT_UNDEFINED
>         la_abs  t0, handle_syscall
>         jr      t0
>  SYM_CODE_END(handle_sys)
> diff --git a/arch/loongarch/kernel/module.c b/arch/loongarch/kernel/module.c
> index b13b285..c7d0338 100644
> --- a/arch/loongarch/kernel/module.c
> +++ b/arch/loongarch/kernel/module.c
> @@ -20,6 +20,7 @@
>  #include <linux/kernel.h>
>  #include <asm/alternative.h>
>  #include <asm/inst.h>
> +#include <asm/unwind.h>
>
>  static int rela_stack_push(s64 stack_value, s64 *rela_stack, size_t *rela_stack_top)
>  {
> @@ -515,15 +516,28 @@ static void module_init_ftrace_plt(const Elf_Ehdr *hdr,
>  int module_finalize(const Elf_Ehdr *hdr,
>                     const Elf_Shdr *sechdrs, struct module *mod)
>  {
> -       const Elf_Shdr *s, *se;
>         const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
> +       const Elf_Shdr *s, *alt = NULL, *orc = NULL, *orc_ip = NULL, *ftrace = NULL;
>
> -       for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++) {
> +       for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
>                 if (!strcmp(".altinstructions", secstrs + s->sh_name))
> -                       apply_alternatives((void *)s->sh_addr, (void *)s->sh_addr + s->sh_size);
> +                       alt = s;
> +               if (!strcmp(".orc_unwind", secstrs + s->sh_name))
> +                       orc = s;
> +               if (!strcmp(".orc_unwind_ip", secstrs + s->sh_name))
> +                       orc_ip = s;
>                 if (!strcmp(".ftrace_trampoline", secstrs + s->sh_name))
> -                       module_init_ftrace_plt(hdr, s, mod);
> +                       ftrace = s;
>         }
>
> +       if (alt)
> +               apply_alternatives((void *)alt->sh_addr, (void *)alt->sh_addr + alt->sh_size);
> +
> +       if (orc && orc_ip)
> +               unwind_module_init(mod, (void *)orc_ip->sh_addr, orc_ip->sh_size, (void *)orc->sh_addr, orc->sh_size);
> +
> +       if (ftrace)
> +               module_init_ftrace_plt(hdr, ftrace, mod);
> +
>         return 0;
>  }
> diff --git a/arch/loongarch/kernel/relocate_kernel.S b/arch/loongarch/kernel/relocate_kernel.S
> index f49f6b0..bcc191d 100644
> --- a/arch/loongarch/kernel/relocate_kernel.S
> +++ b/arch/loongarch/kernel/relocate_kernel.S
> @@ -15,6 +15,7 @@
>  #include <asm/addrspace.h>
>
>  SYM_CODE_START(relocate_new_kernel)
> +       UNWIND_HINT_UNDEFINED
>         /*
>          * a0: EFI boot flag for the new kernel
>          * a1: Command line pointer for the new kernel
> @@ -90,6 +91,7 @@ SYM_CODE_END(relocate_new_kernel)
>   * then start at the entry point from LOONGARCH_IOCSR_MBUF0.
>   */
>  SYM_CODE_START(kexec_smp_wait)
> +       UNWIND_HINT_UNDEFINED
>  1:     li.w            t0, 0x100                       /* wait for init loop */
>  2:     addi.w          t0, t0, -1                      /* limit mailbox access */
>         bnez            t0, 2b
> diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
> index aed65915..613f04d 100644
> --- a/arch/loongarch/kernel/setup.c
> +++ b/arch/loongarch/kernel/setup.c
> @@ -48,6 +48,7 @@
>  #include <asm/sections.h>
>  #include <asm/setup.h>
>  #include <asm/time.h>
> +#include <asm/unwind.h>
>
>  #define SMBIOS_BIOSSIZE_OFFSET         0x09
>  #define SMBIOS_BIOSEXTERN_OFFSET       0x13
> @@ -606,6 +607,7 @@ static void __init prefill_possible_map(void)
>  void __init setup_arch(char **cmdline_p)
>  {
>         cpu_probe();
> +       unwind_init();
>
>         init_environ();
>         efi_init();
> diff --git a/arch/loongarch/kernel/stacktrace.c b/arch/loongarch/kernel/stacktrace.c
> index 92270f1..9848d42 100644
> --- a/arch/loongarch/kernel/stacktrace.c
> +++ b/arch/loongarch/kernel/stacktrace.c
> @@ -29,6 +29,7 @@ void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
>                         regs->csr_era = thread_saved_ra(task);
>                 }
>                 regs->regs[1] = 0;
> +               regs->regs[22] = 0;
>         }
>
>         for (unwind_start(&state, task, regs);
> diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
> index aebfc37..f9f4eb0 100644
> --- a/arch/loongarch/kernel/traps.c
> +++ b/arch/loongarch/kernel/traps.c
> @@ -53,6 +53,32 @@
>
>  #include "access-helper.h"
>
> +void *exception_table[EXCCODE_INT_START] = {
> +       [0 ... EXCCODE_INT_START - 1] = handle_reserved,
> +
> +       [EXCCODE_TLBI]          = handle_tlb_load,
> +       [EXCCODE_TLBL]          = handle_tlb_load,
> +       [EXCCODE_TLBS]          = handle_tlb_store,
> +       [EXCCODE_TLBM]          = handle_tlb_modify,
> +       [EXCCODE_TLBNR]         = handle_tlb_protect,
> +       [EXCCODE_TLBNX]         = handle_tlb_protect,
> +       [EXCCODE_TLBPE]         = handle_tlb_protect,
> +       [EXCCODE_ADE]           = handle_ade,
> +       [EXCCODE_ALE]           = handle_ale,
> +       [EXCCODE_BCE]           = handle_bce,
> +       [EXCCODE_SYS]           = handle_sys,
> +       [EXCCODE_BP]            = handle_bp,
> +       [EXCCODE_INE]           = handle_ri,
> +       [EXCCODE_IPE]           = handle_ri,
> +       [EXCCODE_FPDIS]         = handle_fpu,
> +       [EXCCODE_LSXDIS]        = handle_lsx,
> +       [EXCCODE_LASXDIS]       = handle_lasx,
> +       [EXCCODE_FPE]           = handle_fpe,
> +       [EXCCODE_WATCH]         = handle_watch,
> +       [EXCCODE_BTDIS]         = handle_lbt,
> +};
> +EXPORT_SYMBOL_GPL(exception_table);
> +
>  static void show_backtrace(struct task_struct *task, const struct pt_regs *regs,
>                            const char *loglvl, bool user)
>  {
> @@ -1150,19 +1176,9 @@ void __init trap_init(void)
>         for (i = EXCCODE_INT_START; i <= EXCCODE_INT_END; i++)
>                 set_handler(i * VECSIZE, handle_vint, VECSIZE);
>
> -       set_handler(EXCCODE_ADE * VECSIZE, handle_ade, VECSIZE);
> -       set_handler(EXCCODE_ALE * VECSIZE, handle_ale, VECSIZE);
> -       set_handler(EXCCODE_BCE * VECSIZE, handle_bce, VECSIZE);
> -       set_handler(EXCCODE_SYS * VECSIZE, handle_sys, VECSIZE);
> -       set_handler(EXCCODE_BP * VECSIZE, handle_bp, VECSIZE);
> -       set_handler(EXCCODE_INE * VECSIZE, handle_ri, VECSIZE);
> -       set_handler(EXCCODE_IPE * VECSIZE, handle_ri, VECSIZE);
> -       set_handler(EXCCODE_FPDIS * VECSIZE, handle_fpu, VECSIZE);
> -       set_handler(EXCCODE_LSXDIS * VECSIZE, handle_lsx, VECSIZE);
> -       set_handler(EXCCODE_LASXDIS * VECSIZE, handle_lasx, VECSIZE);
> -       set_handler(EXCCODE_FPE * VECSIZE, handle_fpe, VECSIZE);
> -       set_handler(EXCCODE_BTDIS * VECSIZE, handle_lbt, VECSIZE);
> -       set_handler(EXCCODE_WATCH * VECSIZE, handle_watch, VECSIZE);
> +       /* Set exception vector handler */
> +       for (i = EXCCODE_ADE; i <= EXCCODE_BTDIS; i++)
> +               set_handler(i * VECSIZE, exception_table[i], VECSIZE);
>
>         cache_error_setup();
>
> diff --git a/arch/loongarch/kernel/unwind_orc.c b/arch/loongarch/kernel/unwind_orc.c
> new file mode 100644
> index 0000000..9be5cead
> --- /dev/null
> +++ b/arch/loongarch/kernel/unwind_orc.c
> @@ -0,0 +1,513 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +#include <linux/objtool.h>
> +#include <linux/module.h>
> +#include <linux/sort.h>
> +#include <asm/exception.h>
> +#include <asm/orc_header.h>
> +#include <asm/orc_lookup.h>
> +#include <asm/orc_types.h>
> +#include <asm/ptrace.h>
> +#include <asm/setup.h>
> +#include <asm/stacktrace.h>
> +#include <asm/tlb.h>
> +#include <asm/unwind.h>
> +
> +ORC_HEADER;
> +
> +#define orc_warn(fmt, ...) \
> +       printk_deferred_once(KERN_WARNING "WARNING: " fmt, ##__VA_ARGS__)
> +
> +extern int __start_orc_unwind_ip[];
> +extern int __stop_orc_unwind_ip[];
> +extern struct orc_entry __start_orc_unwind[];
> +extern struct orc_entry __stop_orc_unwind[];
> +
> +static bool orc_init __ro_after_init;
> +static unsigned int lookup_num_blocks __ro_after_init;
> +
> +/* Fake frame pointer entry -- used as a fallback for generated code */
> +static struct orc_entry orc_fp_entry = {
> +       .sp_reg         = ORC_REG_FP,
> +       .sp_offset      = 16,
> +       .fp_reg         = ORC_REG_PREV_SP,
> +       .fp_offset      = -16,
> +       .ra_reg         = ORC_REG_PREV_SP,
> +       .ra_offset      = -8,
> +       .type           = ORC_TYPE_CALL
> +};
> +
> +/*
> + * If we crash with IP==0, the last successfully executed instruction
> + * was probably an indirect function call with a NULL function pointer,
> + * and we don't have unwind information for NULL.
> + * This hardcoded ORC entry for IP==0 allows us to unwind from a NULL function
> + * pointer into its parent and then continue normally from there.
> + */
> +static struct orc_entry orc_null_entry = {
> +       .sp_reg         = ORC_REG_SP,
> +       .sp_offset      = sizeof(long),
> +       .fp_reg         = ORC_REG_UNDEFINED,
> +       .type           = ORC_TYPE_CALL
> +};
> +
> +static inline unsigned long orc_ip(const int *ip)
> +{
> +       return (unsigned long)ip + *ip;
> +}
> +
> +static struct orc_entry *__orc_find(int *ip_table, struct orc_entry *u_table,
> +                                   unsigned int num_entries, unsigned long ip)
> +{
> +       int *first = ip_table;
> +       int *mid = first, *found = first;
> +       int *last = ip_table + num_entries - 1;
> +
> +       if (!num_entries)
> +               return NULL;
> +
> +       /*
> +        * Do a binary range search to find the rightmost duplicate of a given
> +        * starting address.  Some entries are section terminators which are
> +        * "weak" entries for ensuring there are no gaps.  They should be
> +        * ignored when they conflict with a real entry.
> +        */
> +       while (first <= last) {
> +               mid = first + ((last - first) / 2);
> +
> +               if (orc_ip(mid) <= ip) {
> +                       found = mid;
> +                       first = mid + 1;
> +               } else
> +                       last = mid - 1;
> +       }
> +
> +       return u_table + (found - ip_table);
> +}
> +
> +#ifdef CONFIG_MODULES
> +static struct orc_entry *orc_module_find(unsigned long ip)
> +{
> +       struct module *mod;
> +
> +       mod = __module_address(ip);
> +       if (!mod || !mod->arch.orc_unwind || !mod->arch.orc_unwind_ip)
> +               return NULL;
> +
> +       return __orc_find(mod->arch.orc_unwind_ip, mod->arch.orc_unwind, mod->arch.num_orcs, ip);
> +}
> +#else
> +static struct orc_entry *orc_module_find(unsigned long ip)
> +{
> +       return NULL;
> +}
> +#endif
> +
> +#ifdef CONFIG_DYNAMIC_FTRACE
> +static struct orc_entry *orc_find(unsigned long ip);
> +
> +/*
> + * Ftrace dynamic trampolines do not have orc entries of their own.
> + * But they are copies of the ftrace entries that are static and
> + * defined in ftrace_*.S, which do have orc entries.
> + *
> + * If the unwinder comes across a ftrace trampoline, then find the
> + * ftrace function that was used to create it, and use that ftrace
> + * function's orc entry, as the placement of the return code in
> + * the stack will be identical.
> + */
> +static struct orc_entry *orc_ftrace_find(unsigned long ip)
> +{
> +       struct ftrace_ops *ops;
> +       unsigned long tramp_addr, offset;
> +
> +       ops = ftrace_ops_trampoline(ip);
> +       if (!ops)
> +               return NULL;
> +
> +       /* Set tramp_addr to the start of the code copied by the trampoline */
> +       if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)
> +               tramp_addr = (unsigned long)ftrace_regs_caller;
> +       else
> +               tramp_addr = (unsigned long)ftrace_caller;
> +
> +       /* Now place tramp_addr to the location within the trampoline ip is at */
> +       offset = ip - ops->trampoline;
> +       tramp_addr += offset;
> +
> +       /* Prevent unlikely recursion */
> +       if (ip == tramp_addr)
> +               return NULL;
> +
> +       return orc_find(tramp_addr);
> +}
> +#else
> +static struct orc_entry *orc_ftrace_find(unsigned long ip)
> +{
> +       return NULL;
> +}
> +#endif
> +
> +static struct orc_entry *orc_find(unsigned long ip)
> +{
> +       static struct orc_entry *orc;
> +
> +       if (ip == 0)
> +               return &orc_null_entry;
> +
> +       /* For non-init vmlinux addresses, use the fast lookup table: */
> +       if (ip >= LOOKUP_START_IP && ip < LOOKUP_STOP_IP) {
> +               unsigned int idx, start, stop;
> +
> +               idx = (ip - LOOKUP_START_IP) / LOOKUP_BLOCK_SIZE;
> +
> +               if (unlikely((idx >= lookup_num_blocks-1))) {
> +                       orc_warn("WARNING: bad lookup idx: idx=%u num=%u ip=%pB\n",
> +                                idx, lookup_num_blocks, (void *)ip);
> +                       return NULL;
> +               }
> +
> +               start = orc_lookup[idx];
> +               stop = orc_lookup[idx + 1] + 1;
> +
> +               if (unlikely((__start_orc_unwind + start >= __stop_orc_unwind) ||
> +                            (__start_orc_unwind + stop > __stop_orc_unwind))) {
> +                       orc_warn("WARNING: bad lookup value: idx=%u num=%u start=%u stop=%u ip=%pB\n",
> +                                idx, lookup_num_blocks, start, stop, (void *)ip);
> +                       return NULL;
> +               }
> +
> +               return __orc_find(__start_orc_unwind_ip + start,
> +                                 __start_orc_unwind + start, stop - start, ip);
> +       }
> +
> +       /* vmlinux .init slow lookup: */
> +       if (is_kernel_inittext(ip))
> +               return __orc_find(__start_orc_unwind_ip, __start_orc_unwind,
> +                                 __stop_orc_unwind_ip - __start_orc_unwind_ip, ip);
> +
> +       /* Module lookup: */
> +       orc = orc_module_find(ip);
> +       if (orc)
> +               return orc;
> +
> +       return orc_ftrace_find(ip);
> +}
> +
> +#ifdef CONFIG_MODULES
> +
> +static DEFINE_MUTEX(sort_mutex);
> +static int *cur_orc_ip_table = __start_orc_unwind_ip;
> +static struct orc_entry *cur_orc_table = __start_orc_unwind;
> +
> +static void orc_sort_swap(void *_a, void *_b, int size)
> +{
> +       int delta = _b - _a;
> +       int *a = _a, *b = _b, tmp;
> +       struct orc_entry *orc_a, *orc_b;
> +
> +       /* Swap the .orc_unwind_ip entries: */
> +       tmp = *a;
> +       *a = *b + delta;
> +       *b = tmp - delta;
> +
> +       /* Swap the corresponding .orc_unwind entries: */
> +       orc_a = cur_orc_table + (a - cur_orc_ip_table);
> +       orc_b = cur_orc_table + (b - cur_orc_ip_table);
> +       swap(*orc_a, *orc_b);
> +}
> +
> +static int orc_sort_cmp(const void *_a, const void *_b)
> +{
> +       const int *a = _a, *b = _b;
> +       unsigned long a_val = orc_ip(a);
> +       unsigned long b_val = orc_ip(b);
> +       struct orc_entry *orc_a;
> +
> +       if (a_val > b_val)
> +               return 1;
> +       if (a_val < b_val)
> +               return -1;
> +
> +       /*
> +        * The "weak" section terminator entries need to always be first
> +        * to ensure the lookup code skips them in favor of real entries.
> +        * These terminator entries exist to handle any gaps created by
> +        * whitelisted .o files which didn't get objtool generation.
> +        */
> +       orc_a = cur_orc_table + (a - cur_orc_ip_table);
> +
> +       return orc_a->type == ORC_TYPE_UNDEFINED ? -1 : 1;
> +}
> +
> +void unwind_module_init(struct module *mod, void *_orc_ip, size_t orc_ip_size,
> +                       void *_orc, size_t orc_size)
> +{
> +       int *orc_ip = _orc_ip;
> +       struct orc_entry *orc = _orc;
> +       unsigned int num_entries = orc_ip_size / sizeof(int);
> +
> +       WARN_ON_ONCE(orc_ip_size % sizeof(int) != 0 ||
> +                    orc_size % sizeof(*orc) != 0 ||
> +                    num_entries != orc_size / sizeof(*orc));
> +
> +       /*
> +        * The 'cur_orc_*' globals allow the orc_sort_swap() callback to
> +        * associate an .orc_unwind_ip table entry with its corresponding
> +        * .orc_unwind entry so they can both be swapped.
> +        */
> +       mutex_lock(&sort_mutex);
> +       cur_orc_ip_table = orc_ip;
> +       cur_orc_table = orc;
> +       sort(orc_ip, num_entries, sizeof(int), orc_sort_cmp, orc_sort_swap);
> +       mutex_unlock(&sort_mutex);
> +
> +       mod->arch.orc_unwind_ip = orc_ip;
> +       mod->arch.orc_unwind = orc;
> +       mod->arch.num_orcs = num_entries;
> +}
> +#endif
> +
> +void __init unwind_init(void)
> +{
> +       int i;
> +       size_t orc_size = (void *)__stop_orc_unwind - (void *)__start_orc_unwind;
> +       size_t orc_ip_size = (void *)__stop_orc_unwind_ip - (void *)__start_orc_unwind_ip;
> +       size_t num_entries = orc_ip_size / sizeof(int);
> +       struct orc_entry *orc;
> +
> +       if (!num_entries || orc_ip_size % sizeof(int) != 0 ||
> +           orc_size % sizeof(struct orc_entry) != 0 ||
> +           num_entries != orc_size / sizeof(struct orc_entry)) {
> +               orc_warn("WARNING: Bad or missing .orc_unwind table.  Disabling unwinder.\n");
> +               return;
> +       }
> +
> +       /*
> +        * Note, the orc_unwind and orc_unwind_ip tables were already
> +        * sorted at build time via the 'sorttable' tool.
> +        * It's ready for binary search straight away, no need to sort it.
> +        */
> +
> +       /* Initialize the fast lookup table: */
> +       lookup_num_blocks = orc_lookup_end - orc_lookup;
> +       for (i = 0; i < lookup_num_blocks-1; i++) {
> +               orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind,
> +                                num_entries, LOOKUP_START_IP + (LOOKUP_BLOCK_SIZE * i));
> +               if (!orc) {
> +                       orc_warn("WARNING: Corrupt .orc_unwind table.  Disabling unwinder.\n");
> +                       return;
> +               }
> +
> +               orc_lookup[i] = orc - __start_orc_unwind;
> +       }
> +
> +       /* Initialize the ending block: */
> +       orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind, num_entries, LOOKUP_STOP_IP);
> +       if (!orc) {
> +               orc_warn("WARNING: Corrupt .orc_unwind table.  Disabling unwinder.\n");
> +               return;
> +       }
> +       orc_lookup[lookup_num_blocks-1] = orc - __start_orc_unwind;
> +
> +       orc_init = true;
> +}
> +
> +static inline bool on_stack(struct stack_info *info, unsigned long addr, size_t len)
> +{
> +       unsigned long begin = info->begin;
> +       unsigned long end   = info->end;
> +
> +       return (info->type != STACK_TYPE_UNKNOWN &&
> +               addr >= begin && addr < end && addr + len > begin && addr + len <= end);
> +}
> +
> +static bool stack_access_ok(struct unwind_state *state, unsigned long addr, size_t len)
> +{
> +       struct stack_info *info = &state->stack_info;
> +
> +       if (on_stack(info, addr, len))
> +               return true;
> +
> +       return (get_stack_info(addr, state->task, info) == 0);
> +}
> +
> +unsigned long unwind_get_return_address(struct unwind_state *state)
> +{
> +       return __unwind_get_return_address(state);
> +}
> +EXPORT_SYMBOL_GPL(unwind_get_return_address);
> +
> +void unwind_start(struct unwind_state *state, struct task_struct *task,
> +                   struct pt_regs *regs)
> +{
> +       __unwind_start(state, task, regs);
> +       state->type = UNWINDER_ORC;
> +       if (!unwind_done(state) && !__kernel_text_address(state->pc))
> +               unwind_next_frame(state);
> +}
> +EXPORT_SYMBOL_GPL(unwind_start);
> +
> +static bool is_entry_func(unsigned long addr)
> +{
> +       extern u32 kernel_entry;
> +       extern u32 kernel_entry_end;
> +
> +       return addr >= (unsigned long)&kernel_entry && addr < (unsigned long)&kernel_entry_end;
> +}
> +
> +static inline unsigned long bt_address(unsigned long ra)
> +{
> +       extern unsigned long eentry;
> +
> +       if (__kernel_text_address(ra))
> +               return ra;
> +
> +       if (__module_text_address(ra))
> +               return ra;
> +
> +       if (ra >= eentry && ra < eentry +  EXCCODE_INT_END * VECSIZE) {
> +               unsigned long func;
> +               unsigned long type = (ra - eentry) / VECSIZE;
> +               unsigned long offset = (ra - eentry) % VECSIZE;
> +
> +               switch (type) {
> +               case 0 ... EXCCODE_INT_START - 1:
> +                       func = (unsigned long)exception_table[type];
> +                       break;
> +               case EXCCODE_INT_START ... EXCCODE_INT_END:
> +                       func = (unsigned long)handle_vint;
> +                       break;
> +               default:
> +                       func = (unsigned long)handle_reserved;
> +                       break;
> +               }
> +
> +               return func + offset;
> +       }
> +
> +       return ra;
> +}
> +
> +bool unwind_next_frame(struct unwind_state *state)
> +{
> +       unsigned long *p, pc;
> +       struct pt_regs *regs;
> +       struct orc_entry *orc;
> +       struct stack_info *info = &state->stack_info;
> +
> +       if (unwind_done(state))
> +               return false;
> +
> +       /* Don't let modules unload while we're reading their ORC data. */
> +       preempt_disable();
> +
> +       if (is_entry_func(state->pc))
> +               goto end;
> +
> +       orc = orc_find(state->pc);
> +       if (!orc) {
> +               orc = &orc_fp_entry;
> +               state->error = true;
> +       }
> +
> +       switch (orc->sp_reg) {
> +       case ORC_REG_SP:
> +               state->sp = state->sp + orc->sp_offset;
> +               break;
> +       case ORC_REG_FP:
> +               state->sp = state->fp;
> +               break;
> +       default:
> +               orc_warn("unknown SP base reg %d at %pB\n", orc->sp_reg, (void *)state->pc);
> +               goto err;
> +       }
> +
> +       switch (orc->fp_reg) {
> +       case ORC_REG_PREV_SP:
> +               p = (unsigned long *)(state->sp + orc->fp_offset);
> +               if (!stack_access_ok(state, (unsigned long)p, sizeof(unsigned long)))
> +                       goto err;
> +
> +               state->fp = *p;
> +               break;
> +       case ORC_REG_UNDEFINED:
> +               /* Nothing. */
> +               break;
> +       default:
> +               orc_warn("unknown FP base reg %d at %pB\n", orc->fp_reg, (void *)state->pc);
> +               goto err;
> +       }
> +
> +       switch (orc->type) {
> +       case ORC_TYPE_CALL:
> +               if (orc->ra_reg == ORC_REG_PREV_SP) {
> +                       p = (unsigned long *)(state->sp + orc->ra_offset);
> +                       if (!stack_access_ok(state, (unsigned long)p, sizeof(unsigned long)))
> +                               goto err;
> +
> +                       pc = unwind_graph_addr(state, *p, state->sp);
> +                       pc -= LOONGARCH_INSN_SIZE;
> +               } else if (orc->ra_reg == ORC_REG_UNDEFINED) {
> +                       if (!state->ra || state->ra == state->pc)
> +                               goto err;
> +
> +                       pc = unwind_graph_addr(state, state->ra, state->sp);
> +                       pc -=  LOONGARCH_INSN_SIZE;
> +                       state->ra = 0;
> +               } else {
> +                       orc_warn("unknown ra base reg %d at %pB\n", orc->ra_reg, (void *)state->pc);
> +                       goto err;
> +               }
> +               break;
> +       case ORC_TYPE_REGS:
> +               if (state->stack_info.type == STACK_TYPE_IRQ && state->sp == info->end)
> +                       regs = (struct pt_regs *)info->next_sp;
> +               else
> +                       regs = (struct pt_regs *)state->sp;
> +
> +               if (!stack_access_ok(state, (unsigned long)regs, sizeof(*regs)))
> +                       goto err;
> +
> +               if ((info->end == (unsigned long)regs + sizeof(*regs)) &&
> +                   !regs->regs[3] && !regs->regs[1])
> +                       goto end;
> +
> +               if (user_mode(regs))
> +                       goto end;
> +
> +               pc = regs->csr_era;
> +               if (!__kernel_text_address(pc))
> +                       goto err;
> +
> +               state->sp = regs->regs[3];
> +               state->ra = regs->regs[1];
> +               state->fp = regs->regs[22];
> +               get_stack_info(state->sp, state->task, info);
> +
> +               break;
> +       default:
> +               orc_warn("unknown .orc_unwind entry type %d at %pB\n", orc->type, (void *)state->pc);
> +               goto err;
> +       }
> +
> +       state->pc = bt_address(pc);
> +       if (!state->pc) {
> +               pr_err("cannot find unwind pc at %pK\n", (void *)pc);
> +               goto err;
> +       }
> +
> +       if (!__kernel_text_address(state->pc))
> +               goto err;
> +
> +       preempt_enable();
> +       return true;
> +
> +err:
> +       state->error = true;
> +
> +end:
> +       preempt_enable();
> +       state->stack_info.type = STACK_TYPE_UNKNOWN;
> +       return false;
> +}
> +EXPORT_SYMBOL_GPL(unwind_next_frame);
> diff --git a/arch/loongarch/kernel/vmlinux.lds.S b/arch/loongarch/kernel/vmlinux.lds.S
> index bb2ec86..eaa7a91 100644
> --- a/arch/loongarch/kernel/vmlinux.lds.S
> +++ b/arch/loongarch/kernel/vmlinux.lds.S
> @@ -2,6 +2,7 @@
>  #include <linux/sizes.h>
>  #include <asm/asm-offsets.h>
>  #include <asm/thread_info.h>
> +#include <asm/orc_lookup.h>
>
>  #define PAGE_SIZE _PAGE_SIZE
>  #define RO_EXCEPTION_TABLE_ALIGN       4
> @@ -122,6 +123,8 @@ SECTIONS
>         }
>  #endif
>
> +       ORC_UNWIND_TABLE
> +
>         .sdata : {
>                 *(.sdata)
>         }
> diff --git a/arch/loongarch/lib/Makefile b/arch/loongarch/lib/Makefile
> index a77bf160..e3023d9 100644
> --- a/arch/loongarch/lib/Makefile
> +++ b/arch/loongarch/lib/Makefile
> @@ -3,6 +3,8 @@
>  # Makefile for LoongArch-specific library files.
>  #
>
> +OBJECT_FILES_NON_STANDARD := y
> +
>  lib-y  += delay.o memset.o memcpy.o memmove.o \
>            clear_user.o copy_user.o csum.o dump_tlb.o unaligned.o
>
> diff --git a/arch/loongarch/mm/tlb.c b/arch/loongarch/mm/tlb.c
> index 2c0a411..f01172a 100644
> --- a/arch/loongarch/mm/tlb.c
> +++ b/arch/loongarch/mm/tlb.c
> @@ -9,8 +9,9 @@
>  #include <linux/hugetlb.h>
>  #include <linux/export.h>
>
> -#include <asm/cpu.h>
>  #include <asm/bootinfo.h>
> +#include <asm/cpu.h>
> +#include <asm/exception.h>
>  #include <asm/mmu_context.h>
>  #include <asm/pgtable.h>
>  #include <asm/tlb.h>
> @@ -266,24 +267,20 @@ static void setup_tlb_handler(int cpu)
>         setup_ptwalker();
>         local_flush_tlb_all();
>
> +       if (cpu_has_ptw) {
> +               exception_table[EXCCODE_TLBI] = handle_tlb_load_ptw;
> +               exception_table[EXCCODE_TLBL] = handle_tlb_load_ptw;
> +               exception_table[EXCCODE_TLBS] = handle_tlb_store_ptw;
> +               exception_table[EXCCODE_TLBM] = handle_tlb_modify_ptw;
> +       }
> +
>         /* The tlb handlers are generated only once */
>         if (cpu == 0) {
>                 memcpy((void *)tlbrentry, handle_tlb_refill, 0x80);
>                 local_flush_icache_range(tlbrentry, tlbrentry + 0x80);
> -               if (!cpu_has_ptw) {
> -                       set_handler(EXCCODE_TLBI * VECSIZE, handle_tlb_load, VECSIZE);
> -                       set_handler(EXCCODE_TLBL * VECSIZE, handle_tlb_load, VECSIZE);
> -                       set_handler(EXCCODE_TLBS * VECSIZE, handle_tlb_store, VECSIZE);
> -                       set_handler(EXCCODE_TLBM * VECSIZE, handle_tlb_modify, VECSIZE);
> -               } else {
> -                       set_handler(EXCCODE_TLBI * VECSIZE, handle_tlb_load_ptw, VECSIZE);
> -                       set_handler(EXCCODE_TLBL * VECSIZE, handle_tlb_load_ptw, VECSIZE);
> -                       set_handler(EXCCODE_TLBS * VECSIZE, handle_tlb_store_ptw, VECSIZE);
> -                       set_handler(EXCCODE_TLBM * VECSIZE, handle_tlb_modify_ptw, VECSIZE);
> -               }
> -               set_handler(EXCCODE_TLBNR * VECSIZE, handle_tlb_protect, VECSIZE);
> -               set_handler(EXCCODE_TLBNX * VECSIZE, handle_tlb_protect, VECSIZE);
> -               set_handler(EXCCODE_TLBPE * VECSIZE, handle_tlb_protect, VECSIZE);
> +
> +               for (int i = EXCCODE_TLBL; i <= EXCCODE_TLBPE; i++)
> +                       set_handler(i * VECSIZE, exception_table[i], VECSIZE);
>         }
>  #ifdef CONFIG_NUMA
>         else {
> diff --git a/arch/loongarch/mm/tlbex.S b/arch/loongarch/mm/tlbex.S
> index d5d682f..a44387b 100644
> --- a/arch/loongarch/mm/tlbex.S
> +++ b/arch/loongarch/mm/tlbex.S
> @@ -18,6 +18,7 @@
>
>         .macro tlb_do_page_fault, write
>         SYM_CODE_START(tlb_do_page_fault_\write)
> +       UNWIND_HINT_UNDEFINED
>         SAVE_ALL
>         csrrd           a2, LOONGARCH_CSR_BADV
>         move            a0, sp
> @@ -32,6 +33,7 @@
>         tlb_do_page_fault 1
>
>  SYM_CODE_START(handle_tlb_protect)
> +       UNWIND_HINT_UNDEFINED
>         BACKUP_T0T1
>         SAVE_ALL
>         move            a0, sp
> @@ -44,6 +46,7 @@ SYM_CODE_START(handle_tlb_protect)
>  SYM_CODE_END(handle_tlb_protect)
>
>  SYM_CODE_START(handle_tlb_load)
> +       UNWIND_HINT_UNDEFINED
>         csrwr           t0, EXCEPTION_KS0
>         csrwr           t1, EXCEPTION_KS1
>         csrwr           ra, EXCEPTION_KS2
> @@ -190,6 +193,7 @@ nopage_tlb_load:
>  SYM_CODE_END(handle_tlb_load)
>
>  SYM_CODE_START(handle_tlb_load_ptw)
> +       UNWIND_HINT_UNDEFINED
>         csrwr           t0, LOONGARCH_CSR_KS0
>         csrwr           t1, LOONGARCH_CSR_KS1
>         la_abs          t0, tlb_do_page_fault_0
> @@ -197,6 +201,7 @@ SYM_CODE_START(handle_tlb_load_ptw)
>  SYM_CODE_END(handle_tlb_load_ptw)
>
>  SYM_CODE_START(handle_tlb_store)
> +       UNWIND_HINT_UNDEFINED
>         csrwr           t0, EXCEPTION_KS0
>         csrwr           t1, EXCEPTION_KS1
>         csrwr           ra, EXCEPTION_KS2
> @@ -346,6 +351,7 @@ nopage_tlb_store:
>  SYM_CODE_END(handle_tlb_store)
>
>  SYM_CODE_START(handle_tlb_store_ptw)
> +       UNWIND_HINT_UNDEFINED
>         csrwr           t0, LOONGARCH_CSR_KS0
>         csrwr           t1, LOONGARCH_CSR_KS1
>         la_abs          t0, tlb_do_page_fault_1
> @@ -353,6 +359,7 @@ SYM_CODE_START(handle_tlb_store_ptw)
>  SYM_CODE_END(handle_tlb_store_ptw)
>
>  SYM_CODE_START(handle_tlb_modify)
> +       UNWIND_HINT_UNDEFINED
>         csrwr           t0, EXCEPTION_KS0
>         csrwr           t1, EXCEPTION_KS1
>         csrwr           ra, EXCEPTION_KS2
> @@ -500,6 +507,7 @@ nopage_tlb_modify:
>  SYM_CODE_END(handle_tlb_modify)
>
>  SYM_CODE_START(handle_tlb_modify_ptw)
> +       UNWIND_HINT_UNDEFINED
>         csrwr           t0, LOONGARCH_CSR_KS0
>         csrwr           t1, LOONGARCH_CSR_KS1
>         la_abs          t0, tlb_do_page_fault_1
> @@ -507,6 +515,7 @@ SYM_CODE_START(handle_tlb_modify_ptw)
>  SYM_CODE_END(handle_tlb_modify_ptw)
>
>  SYM_CODE_START(handle_tlb_refill)
> +       UNWIND_HINT_UNDEFINED
>         csrwr           t0, LOONGARCH_CSR_TLBRSAVE
>         csrrd           t0, LOONGARCH_CSR_PGD
>         lddir           t0, t0, 3
> diff --git a/arch/loongarch/vdso/Makefile b/arch/loongarch/vdso/Makefile
> index 5c97d1463..997f41c 100644
> --- a/arch/loongarch/vdso/Makefile
> +++ b/arch/loongarch/vdso/Makefile
> @@ -3,6 +3,7 @@
>
>  KASAN_SANITIZE := n
>  KCOV_INSTRUMENT := n
> +OBJECT_FILES_NON_STANDARD := y
>
>  # Include the generic Makefile to check the built vdso.
>  include $(srctree)/lib/vdso/Makefile
> diff --git a/include/linux/compiler.h b/include/linux/compiler.h
> index d7779a1..df29ddb 100644
> --- a/include/linux/compiler.h
> +++ b/include/linux/compiler.h
> @@ -116,6 +116,14 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
>   */
>  #define __stringify_label(n) #n
>
> +#define __annotate_reachable(c) ({                                     \
> +       asm volatile(__stringify_label(c) ":\n\t"                       \
> +                       ".pushsection .discard.reachable\n\t"           \
> +                       ".long " __stringify_label(c) "b - .\n\t"       \
> +                       ".popsection\n\t");                             \
> +})
> +#define annotate_reachable() __annotate_reachable(__COUNTER__)
> +
>  #define __annotate_unreachable(c) ({                                   \
>         asm volatile(__stringify_label(c) ":\n\t"                       \
>                      ".pushsection .discard.unreachable\n\t"            \
> @@ -128,6 +136,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
>  #define __annotate_jump_table __section(".rodata..c_jump_table")
>
>  #else /* !CONFIG_OBJTOOL */
> +#define annotate_reachable()
>  #define annotate_unreachable()
>  #define __annotate_jump_table
>  #endif /* CONFIG_OBJTOOL */
> diff --git a/scripts/Makefile b/scripts/Makefile
> index 576cf64..e4cca53 100644
> --- a/scripts/Makefile
> +++ b/scripts/Makefile
> @@ -31,9 +31,12 @@ HOSTLDLIBS_sign-file = $(shell $(HOSTPKG_CONFIG) --libs libcrypto 2> /dev/null |
>
>  ifdef CONFIG_UNWINDER_ORC
>  ifeq ($(ARCH),x86_64)
> -ARCH := x86
> +SRCARCH := x86
>  endif
> -HOSTCFLAGS_sorttable.o += -I$(srctree)/tools/arch/x86/include
> +ifeq ($(ARCH),loongarch)
> +SRCARCH := loongarch
> +endif
> +HOSTCFLAGS_sorttable.o += -I$(srctree)/tools/arch/$(SRCARCH)/include
>  HOSTCFLAGS_sorttable.o += -DUNWINDER_ORC_ENABLED
>  endif
>
> --
> 2.1.0
>

Re: [PATCH v4 8/8] LoongArch: Add ORC stack unwinder support

Posted by Tiezhu Yang 2 years, 2 months ago

On 10/27/2023 03:02 PM, Huacai Chen wrote:
> v3 works in most cases, v4 cannot work completely (stop at show_stack), why?

There are no obvious differences of this patch between v3 and v4.

> [   61.642993] Call Trace:
> [   61.642995] [<9000000002ad3808>] show_stack+0x40/0x17c

I can not reproduce the above issue with this patch unless remove
the option "-falign-functions" in arch/loongarch/Makefile, please
make sure the option "-falign-functions" is in your test code.

Thanks,
Tiezhu

Re: [PATCH v4 8/8] LoongArch: Add ORC stack unwinder support

Posted by Huacai Chen 2 years, 2 months ago

On Fri, Oct 27, 2023 at 5:25 PM Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
>
>
>
> On 10/27/2023 03:02 PM, Huacai Chen wrote:
> > v3 works in most cases, v4 cannot work completely (stop at show_stack), why?
>
> There are no obvious differences of this patch between v3 and v4.
>
> > [   61.642993] Call Trace:
> > [   61.642995] [<9000000002ad3808>] show_stack+0x40/0x17c
>
> I can not reproduce the above issue with this patch unless remove
> the option "-falign-functions" in arch/loongarch/Makefile, please
> make sure the option "-falign-functions" is in your test code.
A compiler issue? Can you try this one? Thanks.
https://mirrors.wsyu.edu.cn/fedora/linux/Yongbao/cross-toolchain/20231026/

Huacai

>
> Thanks,
> Tiezhu
>
>

Re: [PATCH v4 8/8] LoongArch: Add ORC stack unwinder support

Posted by Xi Ruoyao 2 years, 2 months ago

On Mon, 2023-10-23 at 16:11 +0800, Tiezhu Yang wrote:
> +ifdef CONFIG_OBJTOOL
> +KBUILD_CFLAGS			+= -fno-optimize-sibling-calls -fno-jump-tables -falign-functions=4
> +endif

Why do we need to regress the code generation so much for objtool?

-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University

Re: [PATCH v4 8/8] LoongArch: Add ORC stack unwinder support

Posted by Tiezhu Yang 2 years, 2 months ago

On 10/23/2023 04:43 PM, Xi Ruoyao wrote:
> On Mon, 2023-10-23 at 16:11 +0800, Tiezhu Yang wrote:
>> +ifdef CONFIG_OBJTOOL
>> +KBUILD_CFLAGS			+= -fno-optimize-sibling-calls -fno-jump-tables -falign-functions=4
>> +endif
>
> Why do we need to regress the code generation so much for objtool?

Add the above options is to avoid generating some intractable
instructions for objtool by now, I hope all of the extra options
can be removed if possible.

For example, without -fno-jump-tables, there exist many objtool
warnings like this:

"sibling call from callable instruction with modified stack frame"

If the enhanced special function about jump table is implemented
in objtool, -fno-jump-tables will be removed in the future.

Thanks,
Tiezhu