Documentation/livepatch/reliable-stacktrace.rst | 2 +- arch/x86/entry/entry_64.S | 12 +++---- arch/x86/include/asm/orc_types.h | 14 ++++---- arch/x86/include/asm/unwind_hints.h | 12 ++++--- arch/x86/kernel/ftrace_64.S | 2 +- arch/x86/kernel/head_64.S | 12 +++---- arch/x86/kernel/relocate_kernel_64.S | 10 +++--- arch/x86/kernel/unwind_orc.c | 15 +++------ arch/x86/lib/retpoline.S | 6 ++-- arch/x86/platform/pvh/head.S | 2 +- arch/x86/xen/xen-asm.S | 4 +- arch/x86/xen/xen-head.S | 4 +- include/linux/objtool.h | 10 ++---- include/linux/objtool_types.h | 27 ++++++++++------ scripts/sorttable.h | 2 +- tools/arch/x86/include/asm/orc_types.h | 14 ++++---- tools/include/linux/objtool_types.h | 27 ++++++++++------ tools/objtool/check.c | 2 +- tools/objtool/orc_dump.c | 8 +++-- tools/objtool/orc_gen.c | 26 +++++++-------- 20 files changed, 116 insertions(+), 95 deletions(-)
The following commit has been merged into the objtool/core branch of tip:
Commit-ID: fb799447ae2974a07907906dff5bd4b9e47b7123
Gitweb: https://git.kernel.org/tip/fb799447ae2974a07907906dff5bd4b9e47b7123
Author: Josh Poimboeuf <jpoimboe@kernel.org>
AuthorDate: Wed, 01 Mar 2023 07:13:12 -08:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Thu, 23 Mar 2023 23:18:58 +01:00
x86,objtool: Split UNWIND_HINT_EMPTY in two
Mark reported that the ORC unwinder incorrectly marks an unwind as
reliable when the unwind terminates prematurely in the dark corners of
return_to_handler() due to lack of information about the next frame.
The problem is UNWIND_HINT_EMPTY is used in two different situations:
1) The end of the kernel stack unwind before hitting user entry, boot
code, or fork entry
2) A blind spot in ORC coverage where the unwinder has to bail due to
lack of information about the next frame
The ORC unwinder has no way to tell the difference between the two.
When it encounters an undefined stack state with 'end=1', it blindly
marks the stack reliable, which can break the livepatch consistency
model.
Fix it by splitting UNWIND_HINT_EMPTY into UNWIND_HINT_UNDEFINED and
UNWIND_HINT_END_OF_STACK.
Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/fd6212c8b450d3564b855e1cb48404d6277b4d9f.1677683419.git.jpoimboe@kernel.org
---
Documentation/livepatch/reliable-stacktrace.rst | 2 +-
arch/x86/entry/entry_64.S | 12 +++----
arch/x86/include/asm/orc_types.h | 14 ++++----
arch/x86/include/asm/unwind_hints.h | 12 ++++---
arch/x86/kernel/ftrace_64.S | 2 +-
arch/x86/kernel/head_64.S | 12 +++----
arch/x86/kernel/relocate_kernel_64.S | 10 +++---
arch/x86/kernel/unwind_orc.c | 15 +++------
arch/x86/lib/retpoline.S | 6 ++--
arch/x86/platform/pvh/head.S | 2 +-
arch/x86/xen/xen-asm.S | 4 +-
arch/x86/xen/xen-head.S | 4 +-
include/linux/objtool.h | 10 ++----
include/linux/objtool_types.h | 27 ++++++++++------
scripts/sorttable.h | 2 +-
tools/arch/x86/include/asm/orc_types.h | 14 ++++----
tools/include/linux/objtool_types.h | 27 ++++++++++------
tools/objtool/check.c | 2 +-
tools/objtool/orc_dump.c | 8 +++--
tools/objtool/orc_gen.c | 26 +++++++--------
20 files changed, 116 insertions(+), 95 deletions(-)
diff --git a/Documentation/livepatch/reliable-stacktrace.rst b/Documentation/livepatch/reliable-stacktrace.rst
index 67459d2..d56bb70 100644
--- a/Documentation/livepatch/reliable-stacktrace.rst
+++ b/Documentation/livepatch/reliable-stacktrace.rst
@@ -183,7 +183,7 @@ trampoline or return trampoline. For example, considering the x86_64
.. code-block:: none
SYM_CODE_START(return_to_handler)
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_UNDEFINED
subq $24, %rsp
/* Save the return values */
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 5b93eb7..45e135b 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -205,7 +205,7 @@ syscall_return_via_sysret:
*/
movq %rsp, %rdi
movq PER_CPU_VAR(cpu_tss_rw + TSS_sp0), %rsp
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_END_OF_STACK
pushq RSP-RDI(%rdi) /* RSP */
pushq (%rdi) /* RDI */
@@ -286,7 +286,7 @@ SYM_FUNC_END(__switch_to_asm)
.pushsection .text, "ax"
__FUNC_ALIGN
SYM_CODE_START_NOALIGN(ret_from_fork)
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_END_OF_STACK
ANNOTATE_NOENDBR // copy_thread
CALL_DEPTH_ACCOUNT
movq %rax, %rdi
@@ -303,7 +303,7 @@ SYM_CODE_START_NOALIGN(ret_from_fork)
1:
/* kernel thread */
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_END_OF_STACK
movq %r12, %rdi
CALL_NOSPEC rbx
/*
@@ -643,7 +643,7 @@ SYM_INNER_LABEL(swapgs_restore_regs_and_return_to_usermode, SYM_L_GLOBAL)
*/
movq %rsp, %rdi
movq PER_CPU_VAR(cpu_tss_rw + TSS_sp0), %rsp
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_END_OF_STACK
/* Copy the IRET frame to the trampoline stack. */
pushq 6*8(%rdi) /* SS */
@@ -869,7 +869,7 @@ SYM_CODE_END(exc_xen_hypervisor_callback)
*/
__FUNC_ALIGN
SYM_CODE_START_NOALIGN(xen_failsafe_callback)
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_UNDEFINED
ENDBR
movl %ds, %ecx
cmpw %cx, 0x10(%rsp)
@@ -1520,7 +1520,7 @@ SYM_CODE_END(asm_exc_nmi)
* MSRs to fully disable 32-bit SYSCALL.
*/
SYM_CODE_START(ignore_sysret)
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_END_OF_STACK
ENDBR
mov $-ENOSYS, %eax
sysretl
diff --git a/arch/x86/include/asm/orc_types.h b/arch/x86/include/asm/orc_types.h
index b4d4ec7..46d7e06 100644
--- a/arch/x86/include/asm/orc_types.h
+++ b/arch/x86/include/asm/orc_types.h
@@ -39,9 +39,11 @@
#define ORC_REG_SP_INDIRECT 9
#define ORC_REG_MAX 15
-#define ORC_TYPE_CALL 0
-#define ORC_TYPE_REGS 1
-#define ORC_TYPE_REGS_PARTIAL 2
+#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__
#include <asm/byteorder.h>
@@ -60,16 +62,14 @@ struct orc_entry {
#if defined(__LITTLE_ENDIAN_BITFIELD)
unsigned sp_reg:4;
unsigned bp_reg:4;
- unsigned type:2;
+ unsigned type:3;
unsigned signal:1;
- unsigned end:1;
#elif defined(__BIG_ENDIAN_BITFIELD)
unsigned bp_reg:4;
unsigned sp_reg:4;
unsigned unused:4;
- unsigned end:1;
unsigned signal:1;
- unsigned type:2;
+ unsigned type:3;
#endif
} __packed;
diff --git a/arch/x86/include/asm/unwind_hints.h b/arch/x86/include/asm/unwind_hints.h
index 4c0f28d..01cb969 100644
--- a/arch/x86/include/asm/unwind_hints.h
+++ b/arch/x86/include/asm/unwind_hints.h
@@ -7,13 +7,17 @@
#ifdef __ASSEMBLY__
-.macro UNWIND_HINT_EMPTY
- UNWIND_HINT type=UNWIND_HINT_TYPE_CALL end=1
+.macro UNWIND_HINT_END_OF_STACK
+ UNWIND_HINT type=UNWIND_HINT_TYPE_END_OF_STACK
+.endm
+
+.macro UNWIND_HINT_UNDEFINED
+ UNWIND_HINT type=UNWIND_HINT_TYPE_UNDEFINED
.endm
.macro UNWIND_HINT_ENTRY
VALIDATE_UNRET_BEGIN
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_END_OF_STACK
.endm
.macro UNWIND_HINT_REGS base=%rsp offset=0 indirect=0 extra=1 partial=0 signal=1
@@ -73,7 +77,7 @@
#else
#define UNWIND_HINT_FUNC \
- UNWIND_HINT(UNWIND_HINT_TYPE_FUNC, ORC_REG_SP, 8, 0, 0)
+ UNWIND_HINT(UNWIND_HINT_TYPE_FUNC, ORC_REG_SP, 8, 0)
#endif /* __ASSEMBLY__ */
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S
index 1265ad5..0387732 100644
--- a/arch/x86/kernel/ftrace_64.S
+++ b/arch/x86/kernel/ftrace_64.S
@@ -340,7 +340,7 @@ STACK_FRAME_NON_STANDARD_FP(__fentry__)
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
SYM_CODE_START(return_to_handler)
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_UNDEFINED
ANNOTATE_NOENDBR
subq $16, %rsp
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index ee3ed15..8d8d25c 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -42,7 +42,7 @@ L3_START_KERNEL = pud_index(__START_KERNEL_map)
__HEAD
.code64
SYM_CODE_START_NOALIGN(startup_64)
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_END_OF_STACK
/*
* At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
* and someone has loaded an identity mapped page table
@@ -105,7 +105,7 @@ SYM_CODE_START_NOALIGN(startup_64)
lretq
.Lon_kernel_cs:
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_END_OF_STACK
/* Sanitize CPU configuration */
call verify_cpu
@@ -127,7 +127,7 @@ SYM_CODE_START_NOALIGN(startup_64)
SYM_CODE_END(startup_64)
SYM_CODE_START(secondary_startup_64)
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_END_OF_STACK
ANNOTATE_NOENDBR
/*
* At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
@@ -156,7 +156,7 @@ SYM_CODE_START(secondary_startup_64)
* verify_cpu() above to make sure NX is enabled.
*/
SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL)
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_END_OF_STACK
ANNOTATE_NOENDBR
/*
@@ -238,7 +238,7 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL)
ANNOTATE_RETPOLINE_SAFE
jmp *%rax
1:
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_END_OF_STACK
ANNOTATE_NOENDBR // above
/*
@@ -371,7 +371,7 @@ SYM_CODE_END(secondary_startup_64)
*/
SYM_CODE_START(start_cpu0)
ANNOTATE_NOENDBR
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_END_OF_STACK
movq initial_stack(%rip), %rsp
jmp .Ljump_to_C_code
SYM_CODE_END(start_cpu0)
diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S
index 4a73351..56cab1b 100644
--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S
@@ -43,7 +43,7 @@
.code64
SYM_CODE_START_NOALIGN(relocate_range)
SYM_CODE_START_NOALIGN(relocate_kernel)
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_END_OF_STACK
ANNOTATE_NOENDBR
/*
* %rdi indirection_page
@@ -113,7 +113,7 @@ SYM_CODE_START_NOALIGN(relocate_kernel)
SYM_CODE_END(relocate_kernel)
SYM_CODE_START_LOCAL_NOALIGN(identity_mapped)
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_END_OF_STACK
/* set return address to 0 if not preserving context */
pushq $0
/* store the start address on the stack */
@@ -231,7 +231,7 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped)
SYM_CODE_END(identity_mapped)
SYM_CODE_START_LOCAL_NOALIGN(virtual_mapped)
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_END_OF_STACK
ANNOTATE_NOENDBR // RET target, above
movq RSP(%r8), %rsp
movq CR4(%r8), %rax
@@ -256,8 +256,8 @@ SYM_CODE_END(virtual_mapped)
/* Do the copies */
SYM_CODE_START_LOCAL_NOALIGN(swap_pages)
- UNWIND_HINT_EMPTY
- movq %rdi, %rcx /* Put the page_list in %rcx */
+ UNWIND_HINT_END_OF_STACK
+ movq %rdi, %rcx /* Put the page_list in %rcx */
xorl %edi, %edi
xorl %esi, %esi
jmp 1f
diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 8348ac5..3ac50b7 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -158,7 +158,6 @@ static struct orc_entry orc_fp_entry = {
.sp_offset = 16,
.bp_reg = ORC_REG_PREV_SP,
.bp_offset = -16,
- .end = 0,
};
static struct orc_entry *orc_find(unsigned long ip)
@@ -250,13 +249,13 @@ static int orc_sort_cmp(const void *_a, const void *_b)
return -1;
/*
- * The "weak" section terminator entries need to always be on the left
+ * 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->sp_reg == ORC_REG_UNDEFINED && !orc_a->end ? -1 : 1;
+ return orc_a->type == ORC_TYPE_UNDEFINED ? -1 : 1;
}
void unwind_module_init(struct module *mod, void *_orc_ip, size_t orc_ip_size,
@@ -474,14 +473,12 @@ bool unwind_next_frame(struct unwind_state *state)
*/
orc = &orc_fp_entry;
state->error = true;
- }
-
- /* End-of-stack check for kernel threads: */
- if (orc->sp_reg == ORC_REG_UNDEFINED) {
- if (!orc->end)
+ } else {
+ if (orc->type == ORC_TYPE_UNDEFINED)
goto err;
- goto the_end;
+ if (orc->type == ORC_TYPE_END_OF_STACK)
+ goto the_end;
}
state->signal = orc->signal;
diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S
index 5f61c65..27ef53f 100644
--- a/arch/x86/lib/retpoline.S
+++ b/arch/x86/lib/retpoline.S
@@ -33,7 +33,7 @@
.align RETPOLINE_THUNK_SIZE
SYM_INNER_LABEL(__x86_indirect_thunk_\reg, SYM_L_GLOBAL)
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_UNDEFINED
ANNOTATE_NOENDBR
ALTERNATIVE_2 __stringify(RETPOLINE \reg), \
@@ -75,7 +75,7 @@ SYM_CODE_END(__x86_indirect_thunk_array)
.align RETPOLINE_THUNK_SIZE
SYM_INNER_LABEL(__x86_indirect_call_thunk_\reg, SYM_L_GLOBAL)
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_UNDEFINED
ANNOTATE_NOENDBR
CALL_DEPTH_ACCOUNT
@@ -103,7 +103,7 @@ SYM_CODE_END(__x86_indirect_call_thunk_array)
.align RETPOLINE_THUNK_SIZE
SYM_INNER_LABEL(__x86_indirect_jump_thunk_\reg, SYM_L_GLOBAL)
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_UNDEFINED
ANNOTATE_NOENDBR
POLINE \reg
ANNOTATE_UNRET_SAFE
diff --git a/arch/x86/platform/pvh/head.S b/arch/x86/platform/pvh/head.S
index 7fe564e..c4365a0 100644
--- a/arch/x86/platform/pvh/head.S
+++ b/arch/x86/platform/pvh/head.S
@@ -50,7 +50,7 @@
#define PVH_DS_SEL (PVH_GDT_ENTRY_DS * 8)
SYM_CODE_START_LOCAL(pvh_start_xen)
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_END_OF_STACK
cld
lgdt (_pa(gdt))
diff --git a/arch/x86/xen/xen-asm.S b/arch/x86/xen/xen-asm.S
index 4a184f6..08f1ceb 100644
--- a/arch/x86/xen/xen-asm.S
+++ b/arch/x86/xen/xen-asm.S
@@ -165,7 +165,7 @@ xen_pv_trap asm_exc_xen_hypervisor_callback
SYM_CODE_START(xen_early_idt_handler_array)
i = 0
.rept NUM_EXCEPTION_VECTORS
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_UNDEFINED
ENDBR
pop %rcx
pop %r11
@@ -193,7 +193,7 @@ hypercall_iret = hypercall_page + __HYPERVISOR_iret * 32
* rsp->rax }
*/
SYM_CODE_START(xen_iret)
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_UNDEFINED
ANNOTATE_NOENDBR
pushq $0
jmp hypercall_iret
diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S
index e36ea42..6eafdd1 100644
--- a/arch/x86/xen/xen-head.S
+++ b/arch/x86/xen/xen-head.S
@@ -45,7 +45,7 @@ SYM_CODE_END(hypercall_page)
#ifdef CONFIG_XEN_PV
__INIT
SYM_CODE_START(startup_xen)
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_END_OF_STACK
ANNOTATE_NOENDBR
cld
@@ -71,7 +71,7 @@ SYM_CODE_END(startup_xen)
#ifdef CONFIG_XEN_PV_SMP
.pushsection .text
SYM_CODE_START(asm_cpu_bringup_and_idle)
- UNWIND_HINT_EMPTY
+ UNWIND_HINT_END_OF_STACK
ENDBR
call cpu_bringup_and_idle
diff --git a/include/linux/objtool.h b/include/linux/objtool.h
index 5aa4751..03f82c2 100644
--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -10,7 +10,7 @@
#ifndef __ASSEMBLY__
-#define UNWIND_HINT(type, sp_reg, sp_offset, signal, end) \
+#define UNWIND_HINT(type, sp_reg, sp_offset, signal) \
"987: \n\t" \
".pushsection .discard.unwind_hints\n\t" \
/* struct unwind_hint */ \
@@ -19,7 +19,6 @@
".byte " __stringify(sp_reg) "\n\t" \
".byte " __stringify(type) "\n\t" \
".byte " __stringify(signal) "\n\t" \
- ".byte " __stringify(end) "\n\t" \
".balign 4 \n\t" \
".popsection\n\t"
@@ -91,7 +90,7 @@
* the debuginfo as necessary. It will also warn if it sees any
* inconsistencies.
*/
-.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 end=0
+.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0
.Lhere_\@:
.pushsection .discard.unwind_hints
/* struct unwind_hint */
@@ -100,7 +99,6 @@
.byte \sp_reg
.byte \type
.byte \signal
- .byte \end
.balign 4
.popsection
.endm
@@ -153,14 +151,14 @@
#ifndef __ASSEMBLY__
-#define UNWIND_HINT(type, sp_reg, sp_offset, signal, end) "\n\t"
+#define UNWIND_HINT(type, sp_reg, sp_offset, signal) "\n\t"
#define STACK_FRAME_NON_STANDARD(func)
#define STACK_FRAME_NON_STANDARD_FP(func)
#define ANNOTATE_NOENDBR
#define ASM_REACHABLE
#else
#define ANNOTATE_INTRA_FUNCTION_CALL
-.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 end=0
+.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0
.endm
.macro STACK_FRAME_NON_STANDARD func:req
.endm
diff --git a/include/linux/objtool_types.h b/include/linux/objtool_types.h
index 9787ad0..453a4f4 100644
--- a/include/linux/objtool_types.h
+++ b/include/linux/objtool_types.h
@@ -16,12 +16,18 @@ struct unwind_hint {
u8 sp_reg;
u8 type;
u8 signal;
- u8 end;
};
#endif /* __ASSEMBLY__ */
/*
+ * UNWIND_HINT_TYPE_UNDEFINED: A blind spot in ORC coverage which can result in
+ * a truncated and unreliable stack unwind.
+ *
+ * UNWIND_HINT_TYPE_END_OF_STACK: The end of the kernel stack unwind before
+ * hitting user entry, boot code, or fork entry (when there are no pt_regs
+ * available).
+ *
* UNWIND_HINT_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP
* (the caller's SP right before it made the call). Used for all callable
* functions, i.e. all C code and all callable asm functions.
@@ -32,17 +38,20 @@ struct unwind_hint {
* UNWIND_HINT_TYPE_REGS_PARTIAL: Used in entry code to indicate that
* sp_reg+sp_offset points to the iret return frame.
*
- * UNWIND_HINT_FUNC: Generate the unwind metadata of a callable function.
+ * UNWIND_HINT_TYPE_FUNC: Generate the unwind metadata of a callable function.
* Useful for code which doesn't have an ELF function annotation.
*
- * UNWIND_HINT_ENTRY: machine entry without stack, SYSCALL/SYSENTER etc.
+ * UNWIND_HINT_TYPE_{SAVE,RESTORE}: Save the unwind metadata at a certain
+ * location so that it can be restored later.
*/
-#define UNWIND_HINT_TYPE_CALL 0
-#define UNWIND_HINT_TYPE_REGS 1
-#define UNWIND_HINT_TYPE_REGS_PARTIAL 2
+#define UNWIND_HINT_TYPE_UNDEFINED 0
+#define UNWIND_HINT_TYPE_END_OF_STACK 1
+#define UNWIND_HINT_TYPE_CALL 2
+#define UNWIND_HINT_TYPE_REGS 3
+#define UNWIND_HINT_TYPE_REGS_PARTIAL 4
/* The below hint types don't have corresponding ORC types */
-#define UNWIND_HINT_TYPE_FUNC 3
-#define UNWIND_HINT_TYPE_SAVE 4
-#define UNWIND_HINT_TYPE_RESTORE 5
+#define UNWIND_HINT_TYPE_FUNC 5
+#define UNWIND_HINT_TYPE_SAVE 6
+#define UNWIND_HINT_TYPE_RESTORE 7
#endif /* _LINUX_OBJTOOL_TYPES_H */
diff --git a/scripts/sorttable.h b/scripts/sorttable.h
index deb7c1d..7bd0184 100644
--- a/scripts/sorttable.h
+++ b/scripts/sorttable.h
@@ -128,7 +128,7 @@ static int orc_sort_cmp(const void *_a, const void *_b)
* whitelisted .o files which didn't get objtool generation.
*/
orc_a = g_orc_table + (a - g_orc_ip_table);
- return orc_a->sp_reg == ORC_REG_UNDEFINED && !orc_a->end ? -1 : 1;
+ return orc_a->type == ORC_TYPE_UNDEFINED ? -1 : 1;
}
static void *sort_orctable(void *arg)
diff --git a/tools/arch/x86/include/asm/orc_types.h b/tools/arch/x86/include/asm/orc_types.h
index b4d4ec7..46d7e06 100644
--- a/tools/arch/x86/include/asm/orc_types.h
+++ b/tools/arch/x86/include/asm/orc_types.h
@@ -39,9 +39,11 @@
#define ORC_REG_SP_INDIRECT 9
#define ORC_REG_MAX 15
-#define ORC_TYPE_CALL 0
-#define ORC_TYPE_REGS 1
-#define ORC_TYPE_REGS_PARTIAL 2
+#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__
#include <asm/byteorder.h>
@@ -60,16 +62,14 @@ struct orc_entry {
#if defined(__LITTLE_ENDIAN_BITFIELD)
unsigned sp_reg:4;
unsigned bp_reg:4;
- unsigned type:2;
+ unsigned type:3;
unsigned signal:1;
- unsigned end:1;
#elif defined(__BIG_ENDIAN_BITFIELD)
unsigned bp_reg:4;
unsigned sp_reg:4;
unsigned unused:4;
- unsigned end:1;
unsigned signal:1;
- unsigned type:2;
+ unsigned type:3;
#endif
} __packed;
diff --git a/tools/include/linux/objtool_types.h b/tools/include/linux/objtool_types.h
index 9787ad0..453a4f4 100644
--- a/tools/include/linux/objtool_types.h
+++ b/tools/include/linux/objtool_types.h
@@ -16,12 +16,18 @@ struct unwind_hint {
u8 sp_reg;
u8 type;
u8 signal;
- u8 end;
};
#endif /* __ASSEMBLY__ */
/*
+ * UNWIND_HINT_TYPE_UNDEFINED: A blind spot in ORC coverage which can result in
+ * a truncated and unreliable stack unwind.
+ *
+ * UNWIND_HINT_TYPE_END_OF_STACK: The end of the kernel stack unwind before
+ * hitting user entry, boot code, or fork entry (when there are no pt_regs
+ * available).
+ *
* UNWIND_HINT_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP
* (the caller's SP right before it made the call). Used for all callable
* functions, i.e. all C code and all callable asm functions.
@@ -32,17 +38,20 @@ struct unwind_hint {
* UNWIND_HINT_TYPE_REGS_PARTIAL: Used in entry code to indicate that
* sp_reg+sp_offset points to the iret return frame.
*
- * UNWIND_HINT_FUNC: Generate the unwind metadata of a callable function.
+ * UNWIND_HINT_TYPE_FUNC: Generate the unwind metadata of a callable function.
* Useful for code which doesn't have an ELF function annotation.
*
- * UNWIND_HINT_ENTRY: machine entry without stack, SYSCALL/SYSENTER etc.
+ * UNWIND_HINT_TYPE_{SAVE,RESTORE}: Save the unwind metadata at a certain
+ * location so that it can be restored later.
*/
-#define UNWIND_HINT_TYPE_CALL 0
-#define UNWIND_HINT_TYPE_REGS 1
-#define UNWIND_HINT_TYPE_REGS_PARTIAL 2
+#define UNWIND_HINT_TYPE_UNDEFINED 0
+#define UNWIND_HINT_TYPE_END_OF_STACK 1
+#define UNWIND_HINT_TYPE_CALL 2
+#define UNWIND_HINT_TYPE_REGS 3
+#define UNWIND_HINT_TYPE_REGS_PARTIAL 4
/* The below hint types don't have corresponding ORC types */
-#define UNWIND_HINT_TYPE_FUNC 3
-#define UNWIND_HINT_TYPE_SAVE 4
-#define UNWIND_HINT_TYPE_RESTORE 5
+#define UNWIND_HINT_TYPE_FUNC 5
+#define UNWIND_HINT_TYPE_SAVE 6
+#define UNWIND_HINT_TYPE_RESTORE 7
#endif /* _LINUX_OBJTOOL_TYPES_H */
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 10be80b..cae6ac6 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2243,6 +2243,7 @@ static void set_func_state(struct cfi_state *state)
memcpy(&state->regs, &initial_func_cfi.regs,
CFI_NUM_REGS * sizeof(struct cfi_reg));
state->stack_size = initial_func_cfi.cfa.offset;
+ state->type = UNWIND_HINT_TYPE_CALL;
}
static int read_unwind_hints(struct objtool_file *file)
@@ -2327,7 +2328,6 @@ static int read_unwind_hints(struct objtool_file *file)
cfi.cfa.offset = bswap_if_needed(file->elf, hint->sp_offset);
cfi.type = hint->type;
cfi.signal = hint->signal;
- cfi.end = hint->end;
insn->cfi = cfi_hash_find_or_add(&cfi);
}
diff --git a/tools/objtool/orc_dump.c b/tools/objtool/orc_dump.c
index 97ecbb8..0e183bb 100644
--- a/tools/objtool/orc_dump.c
+++ b/tools/objtool/orc_dump.c
@@ -38,6 +38,10 @@ static const char *reg_name(unsigned int reg)
static const char *orc_type_name(unsigned int type)
{
switch (type) {
+ case ORC_TYPE_UNDEFINED:
+ return "(und)";
+ case ORC_TYPE_END_OF_STACK:
+ return "end";
case ORC_TYPE_CALL:
return "call";
case ORC_TYPE_REGS:
@@ -201,6 +205,7 @@ int orc_dump(const char *_objname)
printf("%llx:", (unsigned long long)(orc_ip_addr + (i * sizeof(int)) + orc_ip[i]));
}
+ printf("type:%s", orc_type_name(orc[i].type));
printf(" sp:");
@@ -210,8 +215,7 @@ int orc_dump(const char *_objname)
print_reg(orc[i].bp_reg, bswap_if_needed(&dummy_elf, orc[i].bp_offset));
- printf(" type:%s signal:%d end:%d\n",
- orc_type_name(orc[i].type), orc[i].signal, orc[i].end);
+ printf(" signal:%d\n", orc[i].signal);
}
elf_end(elf);
diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c
index e85bbb9..b327f9c 100644
--- a/tools/objtool/orc_gen.c
+++ b/tools/objtool/orc_gen.c
@@ -21,12 +21,22 @@ static int init_orc_entry(struct orc_entry *orc, struct cfi_state *cfi,
memset(orc, 0, sizeof(*orc));
if (!cfi) {
- orc->end = 0;
- orc->sp_reg = ORC_REG_UNDEFINED;
+ /*
+ * This is usually either unreachable nops/traps (which don't
+ * trigger unreachable instruction warnings), or
+ * STACK_FRAME_NON_STANDARD functions.
+ */
+ orc->type = ORC_TYPE_UNDEFINED;
return 0;
}
switch (cfi->type) {
+ case UNWIND_HINT_TYPE_UNDEFINED:
+ orc->type = ORC_TYPE_UNDEFINED;
+ return 0;
+ case UNWIND_HINT_TYPE_END_OF_STACK:
+ orc->type = ORC_TYPE_END_OF_STACK;
+ return 0;
case UNWIND_HINT_TYPE_CALL:
orc->type = ORC_TYPE_CALL;
break;
@@ -42,14 +52,8 @@ static int init_orc_entry(struct orc_entry *orc, struct cfi_state *cfi,
return -1;
}
- orc->end = cfi->end;
orc->signal = cfi->signal;
- if (cfi->cfa.base == CFI_UNDEFINED) {
- orc->sp_reg = ORC_REG_UNDEFINED;
- return 0;
- }
-
switch (cfi->cfa.base) {
case CFI_SP:
orc->sp_reg = ORC_REG_SP;
@@ -163,11 +167,7 @@ int orc_create(struct objtool_file *file)
struct orc_list_entry *entry;
struct list_head orc_list;
- struct orc_entry null = {
- .sp_reg = ORC_REG_UNDEFINED,
- .bp_reg = ORC_REG_UNDEFINED,
- .type = ORC_TYPE_CALL,
- };
+ struct orc_entry null = { .type = ORC_TYPE_UNDEFINED };
/* Build a deduplicated list of ORC entries: */
INIT_LIST_HEAD(&orc_list);© 2016 - 2024 Red Hat, Inc.