From: Mao Han <han_mao@c-sky.com> To: linux-riscv@lists.infradead.org Cc: linux-kernel@vger.kernel.org, Mao Han <han_mao@c-sky.com>, Paul Walmsley <paul.walmsley@sifive.com>, Greentime Hu <green.hu@gmail.com>, Palmer Dabbelt <palmer@sifive.com>, Christoph Hellwig <hch@lst.de>, Guo Ren <guoren@kernel.org> Subject: [PATCH V4 1/3] riscv: Add perf callchain support Date: Tue, 20 Aug 2019 16:57:16 +0800 [thread overview] Message-ID: <820d80272fc5627b8d00e684663a614470217606.1566290744.git.han_mao@c-sky.com> (raw) In-Reply-To: <cover.1566290744.git.han_mao@c-sky.com> In-Reply-To: <cover.1566290744.git.han_mao@c-sky.com> This patch add support for perf callchain sampling on riscv platform. The return address of leaf function is retrieved from pt_regs as it is not saved in the outmost frame. Signed-off-by: Mao Han <han_mao@c-sky.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Greentime Hu <green.hu@gmail.com> Cc: Palmer Dabbelt <palmer@sifive.com> Cc: linux-riscv <linux-riscv@lists.infradead.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Guo Ren <guoren@kernel.org> --- arch/riscv/Makefile | 3 + arch/riscv/kernel/Makefile | 3 +- arch/riscv/kernel/perf_callchain.c | 115 +++++++++++++++++++++++++++++++++++++ 3 files changed, 120 insertions(+), 1 deletion(-) create mode 100644 arch/riscv/kernel/perf_callchain.c diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile index 7a117be..946565b 100644 --- a/arch/riscv/Makefile +++ b/arch/riscv/Makefile @@ -54,6 +54,9 @@ endif ifeq ($(CONFIG_MODULE_SECTIONS),y) KBUILD_LDFLAGS_MODULE += -T $(srctree)/arch/riscv/kernel/module.lds endif +ifeq ($(CONFIG_PERF_EVENTS),y) + KBUILD_CFLAGS += -fno-omit-frame-pointer +endif KBUILD_CFLAGS_MODULE += $(call cc-option,-mno-relax) diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index 2420d37..b1bea89 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -38,6 +38,7 @@ obj-$(CONFIG_MODULE_SECTIONS) += module-sections.o obj-$(CONFIG_FUNCTION_TRACER) += mcount.o ftrace.o obj-$(CONFIG_DYNAMIC_FTRACE) += mcount-dyn.o -obj-$(CONFIG_PERF_EVENTS) += perf_event.o +obj-$(CONFIG_PERF_EVENTS) += perf_event.o +obj-$(CONFIG_PERF_EVENTS) += perf_callchain.o clean: diff --git a/arch/riscv/kernel/perf_callchain.c b/arch/riscv/kernel/perf_callchain.c new file mode 100644 index 0000000..d75d15c --- /dev/null +++ b/arch/riscv/kernel/perf_callchain.c @@ -0,0 +1,115 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd. */ + +#include <linux/perf_event.h> +#include <linux/uaccess.h> + +/* Kernel callchain */ +struct stackframe { + unsigned long fp; + unsigned long ra; +}; + +static int unwind_frame_kernel(struct stackframe *frame) +{ + if (kstack_end((void *)frame->fp)) + return -EPERM; + if (frame->fp & 0x3 || frame->fp < TASK_SIZE) + return -EPERM; + if (frame->fp < CONFIG_PAGE_OFFSET) + return -EPERM; + + *frame = *((struct stackframe *)frame->fp - 1); + if (__kernel_text_address(frame->ra)) { + int graph = 0; + + frame->ra = ftrace_graph_ret_addr(NULL, &graph, frame->ra, + NULL); + } + return 0; +} + +static void notrace walk_stackframe(struct stackframe *fr, + struct perf_callchain_entry_ctx *entry) +{ + do { + perf_callchain_store(entry, fr->ra); + } while (unwind_frame_kernel(fr) >= 0); +} + +/* + * Get the return address for a single stackframe and return a pointer to the + * next frame tail. + */ +static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry, + unsigned long fp, unsigned long reg_ra) +{ + struct stackframe buftail; + unsigned long ra = 0; + unsigned long *user_frame_tail = + (unsigned long *)(fp - sizeof(struct stackframe)); + + /* Check accessibility of one struct frame_tail beyond */ + if (!access_ok(user_frame_tail, sizeof(buftail))) + return 0; + if (__copy_from_user_inatomic(&buftail, user_frame_tail, + sizeof(buftail))) + return 0; + + if (reg_ra != 0) + ra = reg_ra; + else + ra = buftail.ra; + + fp = buftail.fp; + perf_callchain_store(entry, ra); + + return fp; +} + +/* + * This will be called when the target is in user mode + * This function will only be called when we use + * "PERF_SAMPLE_CALLCHAIN" in + * kernel/events/core.c:perf_prepare_sample() + * + * How to trigger perf_callchain_[user/kernel] : + * $ perf record -e cpu-clock --call-graph fp ./program + * $ perf report --call-graph + * + * On RISC-V platform, the program being sampled and the C library + * need to be compiled with -fno-omit-frame-pointer, otherwise + * the user stack will not contain function frame. + */ +void perf_callchain_user(struct perf_callchain_entry_ctx *entry, + struct pt_regs *regs) +{ + unsigned long fp = 0; + + /* RISC-V does not support virtualization. */ + if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) + return; + + fp = regs->s0; + perf_callchain_store(entry, regs->sepc); + + fp = user_backtrace(entry, fp, regs->ra); + while (fp && !(fp & 0x3) && entry->nr < entry->max_stack) + fp = user_backtrace(entry, fp, 0); +} + +void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, + struct pt_regs *regs) +{ + struct stackframe fr; + + /* RISC-V does not support virtualization. */ + if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { + pr_warn("RISC-V does not support perf in guest mode!"); + return; + } + + fr.fp = regs->s0; + fr.ra = regs->ra; + walk_stackframe(&fr, entry); +} -- 2.7.4
WARNING: multiple messages have this Message-ID (diff)
From: Mao Han <han_mao@c-sky.com> To: linux-riscv@lists.infradead.org Cc: Palmer Dabbelt <palmer@sifive.com>, linux-kernel@vger.kernel.org, Guo Ren <guoren@kernel.org>, Greentime Hu <green.hu@gmail.com>, Paul Walmsley <paul.walmsley@sifive.com>, Christoph Hellwig <hch@lst.de>, Mao Han <han_mao@c-sky.com> Subject: [PATCH V4 1/3] riscv: Add perf callchain support Date: Tue, 20 Aug 2019 16:57:16 +0800 [thread overview] Message-ID: <820d80272fc5627b8d00e684663a614470217606.1566290744.git.han_mao@c-sky.com> (raw) In-Reply-To: <cover.1566290744.git.han_mao@c-sky.com> In-Reply-To: <cover.1566290744.git.han_mao@c-sky.com> This patch add support for perf callchain sampling on riscv platform. The return address of leaf function is retrieved from pt_regs as it is not saved in the outmost frame. Signed-off-by: Mao Han <han_mao@c-sky.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Greentime Hu <green.hu@gmail.com> Cc: Palmer Dabbelt <palmer@sifive.com> Cc: linux-riscv <linux-riscv@lists.infradead.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Guo Ren <guoren@kernel.org> --- arch/riscv/Makefile | 3 + arch/riscv/kernel/Makefile | 3 +- arch/riscv/kernel/perf_callchain.c | 115 +++++++++++++++++++++++++++++++++++++ 3 files changed, 120 insertions(+), 1 deletion(-) create mode 100644 arch/riscv/kernel/perf_callchain.c diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile index 7a117be..946565b 100644 --- a/arch/riscv/Makefile +++ b/arch/riscv/Makefile @@ -54,6 +54,9 @@ endif ifeq ($(CONFIG_MODULE_SECTIONS),y) KBUILD_LDFLAGS_MODULE += -T $(srctree)/arch/riscv/kernel/module.lds endif +ifeq ($(CONFIG_PERF_EVENTS),y) + KBUILD_CFLAGS += -fno-omit-frame-pointer +endif KBUILD_CFLAGS_MODULE += $(call cc-option,-mno-relax) diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index 2420d37..b1bea89 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -38,6 +38,7 @@ obj-$(CONFIG_MODULE_SECTIONS) += module-sections.o obj-$(CONFIG_FUNCTION_TRACER) += mcount.o ftrace.o obj-$(CONFIG_DYNAMIC_FTRACE) += mcount-dyn.o -obj-$(CONFIG_PERF_EVENTS) += perf_event.o +obj-$(CONFIG_PERF_EVENTS) += perf_event.o +obj-$(CONFIG_PERF_EVENTS) += perf_callchain.o clean: diff --git a/arch/riscv/kernel/perf_callchain.c b/arch/riscv/kernel/perf_callchain.c new file mode 100644 index 0000000..d75d15c --- /dev/null +++ b/arch/riscv/kernel/perf_callchain.c @@ -0,0 +1,115 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd. */ + +#include <linux/perf_event.h> +#include <linux/uaccess.h> + +/* Kernel callchain */ +struct stackframe { + unsigned long fp; + unsigned long ra; +}; + +static int unwind_frame_kernel(struct stackframe *frame) +{ + if (kstack_end((void *)frame->fp)) + return -EPERM; + if (frame->fp & 0x3 || frame->fp < TASK_SIZE) + return -EPERM; + if (frame->fp < CONFIG_PAGE_OFFSET) + return -EPERM; + + *frame = *((struct stackframe *)frame->fp - 1); + if (__kernel_text_address(frame->ra)) { + int graph = 0; + + frame->ra = ftrace_graph_ret_addr(NULL, &graph, frame->ra, + NULL); + } + return 0; +} + +static void notrace walk_stackframe(struct stackframe *fr, + struct perf_callchain_entry_ctx *entry) +{ + do { + perf_callchain_store(entry, fr->ra); + } while (unwind_frame_kernel(fr) >= 0); +} + +/* + * Get the return address for a single stackframe and return a pointer to the + * next frame tail. + */ +static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry, + unsigned long fp, unsigned long reg_ra) +{ + struct stackframe buftail; + unsigned long ra = 0; + unsigned long *user_frame_tail = + (unsigned long *)(fp - sizeof(struct stackframe)); + + /* Check accessibility of one struct frame_tail beyond */ + if (!access_ok(user_frame_tail, sizeof(buftail))) + return 0; + if (__copy_from_user_inatomic(&buftail, user_frame_tail, + sizeof(buftail))) + return 0; + + if (reg_ra != 0) + ra = reg_ra; + else + ra = buftail.ra; + + fp = buftail.fp; + perf_callchain_store(entry, ra); + + return fp; +} + +/* + * This will be called when the target is in user mode + * This function will only be called when we use + * "PERF_SAMPLE_CALLCHAIN" in + * kernel/events/core.c:perf_prepare_sample() + * + * How to trigger perf_callchain_[user/kernel] : + * $ perf record -e cpu-clock --call-graph fp ./program + * $ perf report --call-graph + * + * On RISC-V platform, the program being sampled and the C library + * need to be compiled with -fno-omit-frame-pointer, otherwise + * the user stack will not contain function frame. + */ +void perf_callchain_user(struct perf_callchain_entry_ctx *entry, + struct pt_regs *regs) +{ + unsigned long fp = 0; + + /* RISC-V does not support virtualization. */ + if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) + return; + + fp = regs->s0; + perf_callchain_store(entry, regs->sepc); + + fp = user_backtrace(entry, fp, regs->ra); + while (fp && !(fp & 0x3) && entry->nr < entry->max_stack) + fp = user_backtrace(entry, fp, 0); +} + +void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, + struct pt_regs *regs) +{ + struct stackframe fr; + + /* RISC-V does not support virtualization. */ + if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { + pr_warn("RISC-V does not support perf in guest mode!"); + return; + } + + fr.fp = regs->s0; + fr.ra = regs->ra; + walk_stackframe(&fr, entry); +} -- 2.7.4 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2019-08-20 8:57 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-08-20 8:57 [PATCH V4 0/3] riscv: Add perf callchain support Mao Han 2019-08-20 8:57 ` Mao Han 2019-08-20 8:57 ` Mao Han [this message] 2019-08-20 8:57 ` [PATCH V4 1/3] " Mao Han 2019-08-21 9:16 ` Greentime Hu 2019-08-21 9:16 ` Greentime Hu 2019-08-21 10:57 ` Mao Han 2019-08-21 10:57 ` Mao Han 2019-08-20 8:57 ` [PATCH V4 2/3] riscv: Add support for perf registers sampling Mao Han 2019-08-20 8:57 ` Mao Han 2019-08-20 8:57 ` [PATCH V4 3/3] riscv: Add support for libdw Mao Han 2019-08-20 8:57 ` Mao Han
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