From nobody Sun Apr 5 16:31:37 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2BA89C32771 for ; Fri, 16 Sep 2022 02:56:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229473AbiIPCz6 (ORCPT ); Thu, 15 Sep 2022 22:55:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37022 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229503AbiIPCzs (ORCPT ); Thu, 15 Sep 2022 22:55:48 -0400 Received: from loongson.cn (mail.loongson.cn [114.242.206.163]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 3F1C599B5A for ; Thu, 15 Sep 2022 19:55:46 -0700 (PDT) Received: from localhost.localdomain (unknown [113.200.148.30]) by localhost.localdomain (Coremail) with SMTP id AQAAf8CxbWul5SNj08gaAA--.56059S3; Fri, 16 Sep 2022 10:55:37 +0800 (CST) From: Qing Zhang To: Huacai Chen , Steven Rostedt , Ingo Molnar Cc: WANG Xuerui , loongarch@lists.linux.dev, linux-kernel@vger.kernel.org, Jinyang He Subject: [PATCH v4 01/10] LoongArch/ftrace: Add basic support Date: Fri, 16 Sep 2022 10:55:24 +0800 Message-Id: <20220916025533.18771-2-zhangqing@loongson.cn> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20220916025533.18771-1-zhangqing@loongson.cn> References: <20220916025533.18771-1-zhangqing@loongson.cn> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: AQAAf8CxbWul5SNj08gaAA--.56059S3 X-Coremail-Antispam: 1UD129KBjvJXoW3GFW5ZF1kXr1rGr1fXr1fZwb_yoW3ZF1DpF Zay3WkG397GFsakrWS9r15urn8Jrs7ury2gFZFyryFyFsrXF1rZwn2yryqqF97tws7CrWI ga4fGr42kF45XwUanT9S1TB71UUUUUJqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUQm14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_Jr4l82xGYIkIc2 x26xkF7I0E14v26r1I6r4UM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJw A2z4x0Y4vEx4A2jsIE14v26r4UJVWxJr1l84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s0D M2kKe7AKxVWUXVWUAwAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4 xG6I80ewAv7VC0I7IYx2IY67AKxVWUAVWUtwAv7VC2z280aVAFwI0_Gr0_Cr1lOx8S6xCa FVCjc4AY6r1j6r4UM4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwCY1x 0262kKe7AKxVWUAVWUtwCY02Avz4vE14v_Gr1l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC 6x0Yz7v_Jr0_Gr1l4IxYO2xFxVAFwI0_Jrv_JF1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s 026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r126r1DMIIYrxkI7VAKI48JMIIF 0xvE2Ix0cI8IcVAFwI0_Gr0_Xr1lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4UMIIF0x vE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVW8JVWxJwCI42IY6I8E87Iv 6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjfU11vaUUUUU X-CM-SenderInfo: x2kd0wptlqwqxorr0wxvrqhubq/ Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" This patch contains basic ftrace support for LoongArch. Specifically, function tracer (HAVE_FUNCTION_TRACER), function graph tracer (HAVE_FUNCTION_GRAPH_TRACER) are implemented following the instructions in Documentation/trace/ftrace-design.txt. Use `-pg` makes stub like a child function `void _mcount(void *ra)`. Thus, it can be seen store RA and open stack before `call _mcount`. Find `open stack` at first, and then find `store RA` Note that the functions in both inst.c and time.c should not be hooked with the compiler's -pg option: to prevent infinite self- referencing for the former, and to ignore early setup stuff for the latter. Co-developed-by: Jinyang He Signed-off-by: Jinyang He Signed-off-by: Qing Zhang --- arch/loongarch/Kconfig | 2 + arch/loongarch/Makefile | 5 ++ arch/loongarch/include/asm/ftrace.h | 18 ++++++ arch/loongarch/kernel/Makefile | 8 +++ arch/loongarch/kernel/ftrace.c | 74 +++++++++++++++++++++++ arch/loongarch/kernel/mcount.S | 94 +++++++++++++++++++++++++++++ 6 files changed, 201 insertions(+) create mode 100644 arch/loongarch/include/asm/ftrace.h create mode 100644 arch/loongarch/kernel/ftrace.c create mode 100644 arch/loongarch/kernel/mcount.S diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig index 9b1f2ab878e9..95eab9611191 100644 --- a/arch/loongarch/Kconfig +++ b/arch/loongarch/Kconfig @@ -90,6 +90,8 @@ config LOONGARCH select HAVE_EBPF_JIT select HAVE_EXIT_THREAD select HAVE_FAST_GUP + select HAVE_FUNCTION_GRAPH_TRACER + select HAVE_FUNCTION_TRACER select HAVE_GENERIC_VDSO select HAVE_IOREMAP_PROT select HAVE_IRQ_EXIT_ON_IRQ_STACK diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile index 69b39ba3a09d..1149a17dc04f 100644 --- a/arch/loongarch/Makefile +++ b/arch/loongarch/Makefile @@ -33,6 +33,11 @@ ifneq ($(SUBARCH),$(ARCH)) endif endif =20 +ifdef CONFIG_DYNAMIC_FTRACE + KBUILD_CPPFLAGS +=3D -DCC_USING_PATCHABLE_FUNCTION_ENTRY + CC_FLAGS_FTRACE :=3D -fpatchable-function-entry=3D2 +endif + ifdef CONFIG_64BIT ld-emul =3D $(64bit-emul) cflags-y +=3D -mabi=3Dlp64s diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/a= sm/ftrace.h new file mode 100644 index 000000000000..6a3e76234618 --- /dev/null +++ b/arch/loongarch/include/asm/ftrace.h @@ -0,0 +1,18 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2022 Loongson Technology Corporation Limited + */ + +#ifndef _ASM_LOONGARCH_FTRACE_H +#define _ASM_LOONGARCH_FTRACE_H + +#ifdef CONFIG_FUNCTION_TRACER +#define MCOUNT_INSN_SIZE 4 /* sizeof mcount call */ + +#ifndef __ASSEMBLY__ +extern void _mcount(void); +#define mcount _mcount + +#endif /* __ASSEMBLY__ */ +#endif /* CONFIG_FUNCTION_TRACER */ +#endif /* _ASM_LOONGARCH_FTRACE_H */ diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile index 7225916dd378..7db7ab152f71 100644 --- a/arch/loongarch/kernel/Makefile +++ b/arch/loongarch/kernel/Makefile @@ -14,6 +14,14 @@ obj-$(CONFIG_EFI) +=3D efi.o =20 obj-$(CONFIG_CPU_HAS_FPU) +=3D fpu.o =20 +ifdef CONFIG_FUNCTION_TRACER + obj-y +=3D mcount.o ftrace.o + CFLAGS_REMOVE_ftrace.o =3D $(CC_FLAGS_FTRACE) + CFLAGS_REMOVE_inst.o =3D $(CC_FLAGS_FTRACE) + CFLAGS_REMOVE_time.o =3D $(CC_FLAGS_FTRACE) + CFLAGS_REMOVE_perf_event.o =3D $(CC_FLAGS_FTRACE) +endif + obj-$(CONFIG_MODULES) +=3D module.o module-sections.o obj-$(CONFIG_STACKTRACE) +=3D stacktrace.o =20 diff --git a/arch/loongarch/kernel/ftrace.c b/arch/loongarch/kernel/ftrace.c new file mode 100644 index 000000000000..c8ddc5f11f32 --- /dev/null +++ b/arch/loongarch/kernel/ftrace.c @@ -0,0 +1,74 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2022 Loongson Technology Corporation Limited + */ + +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include +#include + +#include + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + +/* + * As `call _mcount` follows LoongArch psABI, ra-saved operation and + * stack operation can be found before this insn. + */ + +static int ftrace_get_parent_ra_addr(unsigned long insn_addr, int *ra_off) +{ + union loongarch_instruction *insn; + int limit =3D 32; + + insn =3D (union loongarch_instruction *)insn_addr; + + do { + insn--; + limit--; + + if (is_ra_save_ins(insn)) + *ra_off =3D -((1 << 12) - insn->reg2i12_format.immediate); + + } while (!is_stack_alloc_ins(insn) && limit); + + if (!limit) + return -EINVAL; + + return 0; +} + +void prepare_ftrace_return(unsigned long self_addr, + unsigned long callsite_sp, unsigned long old) +{ + int ra_off; + unsigned long return_hooker =3D (unsigned long)&return_to_handler; + + if (unlikely(ftrace_graph_is_dead())) + return; + + if (unlikely(atomic_read(¤t->tracing_graph_pause))) + return; + + if (ftrace_get_parent_ra_addr(self_addr, &ra_off)) + goto out; + + if (!function_graph_enter(old, self_addr, 0, NULL)) + *(unsigned long *)(callsite_sp + ra_off) =3D return_hooker; + + return; + +out: + ftrace_graph_stop(); + WARN_ON(1); +} +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ diff --git a/arch/loongarch/kernel/mcount.S b/arch/loongarch/kernel/mcount.S new file mode 100644 index 000000000000..3de7c2d7fd12 --- /dev/null +++ b/arch/loongarch/kernel/mcount.S @@ -0,0 +1,94 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * LoongArch specific _mcount support + * + * Copyright (C) 2022 Loongson Technology Corporation Limited + */ + +#include +#include +#include +#include + + .text + +#define MCOUNT_STACK_SIZE (2 * SZREG) +#define MCOUNT_S0_OFFSET (0) +#define MCOUNT_RA_OFFSET (SZREG) + + .macro MCOUNT_SAVE_REGS + PTR_ADDI sp, sp, -MCOUNT_STACK_SIZE + PTR_S s0, sp, MCOUNT_S0_OFFSET + PTR_S ra, sp, MCOUNT_RA_OFFSET + move s0, a0 + .endm + + .macro MCOUNT_RESTORE_REGS + move a0, s0 + PTR_L ra, sp, MCOUNT_RA_OFFSET + PTR_L s0, sp, MCOUNT_S0_OFFSET + PTR_ADDI sp, sp, MCOUNT_STACK_SIZE + .endm + + +SYM_FUNC_START(_mcount) + la.pcrel t1, ftrace_stub + la.pcrel t2, ftrace_trace_function /* Prepare t2 for (1) */ + PTR_L t2, t2, 0 + beq t1, t2, fgraph_trace + + MCOUNT_SAVE_REGS + + move a0, ra /* arg0: self return address */ + move a1, s0 /* arg1: parent's return address */ + jirl ra, t2, 0 /* (1) call *ftrace_trace_function */ + + MCOUNT_RESTORE_REGS + +fgraph_trace: +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + la.pcrel t1, ftrace_stub + la.pcrel t3, ftrace_graph_return + PTR_L t3, t3, 0 + bne t1, t3, ftrace_graph_caller + la.pcrel t1, ftrace_graph_entry_stub + la.pcrel t3, ftrace_graph_entry + PTR_L t3, t3, 0 + bne t1, t3, ftrace_graph_caller +#endif + + .globl ftrace_stub +ftrace_stub: + jr ra +SYM_FUNC_END(_mcount) +EXPORT_SYMBOL(_mcount) + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +SYM_FUNC_START(ftrace_graph_caller) + MCOUNT_SAVE_REGS + + PTR_ADDI a0, ra, -4 /* arg0: Callsite self return addr */ + PTR_ADDI a1, sp, MCOUNT_STACK_SIZE /* arg1: Callsite sp */ + move a2, s0 /* arg2: Callsite parent ra */ + bl prepare_ftrace_return + + MCOUNT_RESTORE_REGS + jr ra +SYM_FUNC_END(ftrace_graph_caller) + +SYM_FUNC_START(return_to_handler) + PTR_ADDI sp, sp, -2 * SZREG + PTR_S a0, sp, 0 + PTR_S a1, sp, SZREG + + bl ftrace_return_to_handler + + /* restore the real parent address: a0 -> ra */ + move ra, a0 + + PTR_L a0, sp, 0 + PTR_L a1, sp, SZREG + PTR_ADDI sp, sp, 2 * SZREG + jr ra +SYM_FUNC_END(return_to_handler) +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ --=20 2.36.1