From: guoren@kernel.org To: palmerdabbelt@google.com, paul.walmsley@sifive.com, mhiramat@kernel.org, alankao@andestech.com, rostedt@goodmis.org, bjorn.topel@intel.com, pdp7pdp7@gmail.com Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, anup@brainfault.org, linux-csky@vger.kernel.org, greentime.hu@sifive.com, zong.li@sifive.com, guoren@kernel.org, me@packi.ch, "Guo Ren" <guoren@linux.alibaba.com>, "Björn Töpel" <bjorn.topel@gmail.com>, "Pekka Enberg" <penberg@kernel.org> Subject: [PATCH v5 7/9] riscv: Add KPROBES_ON_FTRACE supported Date: Thu, 17 Dec 2020 16:01:43 +0000 [thread overview] Message-ID: <1608220905-1962-8-git-send-email-guoren@kernel.org> (raw) In-Reply-To: <1608220905-1962-1-git-send-email-guoren@kernel.org> From: Guo Ren <guoren@linux.alibaba.com> This patch adds support for kprobes on ftrace call sites to avoids much of the overhead with regular kprobes. Try it with simple steps: echo 'p:myprobe sys_clone a0=%a0 a1=%a1 stack_val=+4($stack)' > /sys/kernel/de bug/tracing/kprobe_events echo 1 > /sys/kernel/debug/tracing/events/kprobes/enable cat /sys/kernel/debug/tracing/trace tracer: nop entries-in-buffer/entries-written: 1/1 #P:1 _-----=> irqs-off / _----=> need-resched | / _---=> hardirq/softirq || / _--=> preempt-depth ||| / delay TASK-PID CPU# |||| TIMESTAMP FUNCTION | | | |||| | | sh-92 [000] .... 369.899962: myprobe: (sys_clone+0x0/0x28) a0=0x1200011 a1=0x0 stack_val=0x201c20ffffffe0 cat /sys/kernel/debug/kprobes/list ffffffe00020b584 k sys_clone+0x0 [FTRACE] ^^^^^^ Signed-off-by: Guo Ren <guoren@linux.alibaba.com> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Cc: Palmer Dabbelt <palmerdabbelt@google.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Björn Töpel <bjorn.topel@gmail.com> Cc: Zong Li <zong.li@sifive.com> Cc: Pekka Enberg <penberg@kernel.org> --- arch/riscv/Kconfig | 1 + arch/riscv/kernel/probes/Makefile | 1 + arch/riscv/kernel/probes/ftrace.c | 53 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 55 insertions(+) create mode 100644 arch/riscv/kernel/probes/ftrace.c diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 9a920ed..f58b234 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -69,6 +69,7 @@ config RISCV select HAVE_GCC_PLUGINS select HAVE_GENERIC_VDSO if MMU && 64BIT select HAVE_KPROBES + select HAVE_KPROBES_ON_FTRACE select HAVE_KRETPROBES select HAVE_PCI select HAVE_PERF_EVENTS diff --git a/arch/riscv/kernel/probes/Makefile b/arch/riscv/kernel/probes/Makefile index 8a39507..abbd131 100644 --- a/arch/riscv/kernel/probes/Makefile +++ b/arch/riscv/kernel/probes/Makefile @@ -1,4 +1,5 @@ # SPDX-License-Identifier: GPL-2.0 obj-$(CONFIG_KPROBES) += kprobes.o decode-insn.o simulate-insn.o obj-$(CONFIG_KPROBES) += kprobes_trampoline.o +obj-$(CONFIG_KPROBES_ON_FTRACE) += ftrace.o CFLAGS_REMOVE_simulate-insn.o = $(CC_FLAGS_FTRACE) diff --git a/arch/riscv/kernel/probes/ftrace.c b/arch/riscv/kernel/probes/ftrace.c new file mode 100644 index 00000000..c7ccfff --- /dev/null +++ b/arch/riscv/kernel/probes/ftrace.c @@ -0,0 +1,53 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/kprobes.h> + +/* Ftrace callback handler for kprobes -- called under preepmt disabed */ +void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *ops, struct pt_regs *regs) +{ + struct kprobe *p; + struct kprobe_ctlblk *kcb; + + p = get_kprobe((kprobe_opcode_t *)ip); + if (unlikely(!p) || kprobe_disabled(p)) + return; + + kcb = get_kprobe_ctlblk(); + if (kprobe_running()) { + kprobes_inc_nmissed_count(p); + } else { + unsigned long orig_ip = instruction_pointer(regs); + + instruction_pointer_set(regs, ip); + + __this_cpu_write(current_kprobe, p); + kcb->kprobe_status = KPROBE_HIT_ACTIVE; + if (!p->pre_handler || !p->pre_handler(p, regs)) { + /* + * Emulate singlestep (and also recover regs->pc) + * as if there is a nop + */ + instruction_pointer_set(regs, + (unsigned long)p->addr + MCOUNT_INSN_SIZE); + if (unlikely(p->post_handler)) { + kcb->kprobe_status = KPROBE_HIT_SSDONE; + p->post_handler(p, regs, 0); + } + instruction_pointer_set(regs, orig_ip); + } + + /* + * If pre_handler returns !0, it changes regs->pc. We have to + * skip emulating post_handler. + */ + __this_cpu_write(current_kprobe, NULL); + } +} +NOKPROBE_SYMBOL(kprobe_ftrace_handler); + +int arch_prepare_kprobe_ftrace(struct kprobe *p) +{ + p->ainsn.api.insn = NULL; + return 0; +} -- 2.7.4
WARNING: multiple messages have this Message-ID (diff)
From: guoren@kernel.org To: palmerdabbelt@google.com, paul.walmsley@sifive.com, mhiramat@kernel.org, alankao@andestech.com, rostedt@goodmis.org, bjorn.topel@intel.com, pdp7pdp7@gmail.com Cc: me@packi.ch, "Guo Ren" <guoren@linux.alibaba.com>, anup@brainfault.org, linux-kernel@vger.kernel.org, linux-csky@vger.kernel.org, "Pekka Enberg" <penberg@kernel.org>, guoren@kernel.org, zong.li@sifive.com, "Björn Töpel" <bjorn.topel@gmail.com>, greentime.hu@sifive.com, linux-riscv@lists.infradead.org Subject: [PATCH v5 7/9] riscv: Add KPROBES_ON_FTRACE supported Date: Thu, 17 Dec 2020 16:01:43 +0000 [thread overview] Message-ID: <1608220905-1962-8-git-send-email-guoren@kernel.org> (raw) In-Reply-To: <1608220905-1962-1-git-send-email-guoren@kernel.org> From: Guo Ren <guoren@linux.alibaba.com> This patch adds support for kprobes on ftrace call sites to avoids much of the overhead with regular kprobes. Try it with simple steps: echo 'p:myprobe sys_clone a0=%a0 a1=%a1 stack_val=+4($stack)' > /sys/kernel/de bug/tracing/kprobe_events echo 1 > /sys/kernel/debug/tracing/events/kprobes/enable cat /sys/kernel/debug/tracing/trace tracer: nop entries-in-buffer/entries-written: 1/1 #P:1 _-----=> irqs-off / _----=> need-resched | / _---=> hardirq/softirq || / _--=> preempt-depth ||| / delay TASK-PID CPU# |||| TIMESTAMP FUNCTION | | | |||| | | sh-92 [000] .... 369.899962: myprobe: (sys_clone+0x0/0x28) a0=0x1200011 a1=0x0 stack_val=0x201c20ffffffe0 cat /sys/kernel/debug/kprobes/list ffffffe00020b584 k sys_clone+0x0 [FTRACE] ^^^^^^ Signed-off-by: Guo Ren <guoren@linux.alibaba.com> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Cc: Palmer Dabbelt <palmerdabbelt@google.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Björn Töpel <bjorn.topel@gmail.com> Cc: Zong Li <zong.li@sifive.com> Cc: Pekka Enberg <penberg@kernel.org> --- arch/riscv/Kconfig | 1 + arch/riscv/kernel/probes/Makefile | 1 + arch/riscv/kernel/probes/ftrace.c | 53 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 55 insertions(+) create mode 100644 arch/riscv/kernel/probes/ftrace.c diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 9a920ed..f58b234 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -69,6 +69,7 @@ config RISCV select HAVE_GCC_PLUGINS select HAVE_GENERIC_VDSO if MMU && 64BIT select HAVE_KPROBES + select HAVE_KPROBES_ON_FTRACE select HAVE_KRETPROBES select HAVE_PCI select HAVE_PERF_EVENTS diff --git a/arch/riscv/kernel/probes/Makefile b/arch/riscv/kernel/probes/Makefile index 8a39507..abbd131 100644 --- a/arch/riscv/kernel/probes/Makefile +++ b/arch/riscv/kernel/probes/Makefile @@ -1,4 +1,5 @@ # SPDX-License-Identifier: GPL-2.0 obj-$(CONFIG_KPROBES) += kprobes.o decode-insn.o simulate-insn.o obj-$(CONFIG_KPROBES) += kprobes_trampoline.o +obj-$(CONFIG_KPROBES_ON_FTRACE) += ftrace.o CFLAGS_REMOVE_simulate-insn.o = $(CC_FLAGS_FTRACE) diff --git a/arch/riscv/kernel/probes/ftrace.c b/arch/riscv/kernel/probes/ftrace.c new file mode 100644 index 00000000..c7ccfff --- /dev/null +++ b/arch/riscv/kernel/probes/ftrace.c @@ -0,0 +1,53 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/kprobes.h> + +/* Ftrace callback handler for kprobes -- called under preepmt disabed */ +void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *ops, struct pt_regs *regs) +{ + struct kprobe *p; + struct kprobe_ctlblk *kcb; + + p = get_kprobe((kprobe_opcode_t *)ip); + if (unlikely(!p) || kprobe_disabled(p)) + return; + + kcb = get_kprobe_ctlblk(); + if (kprobe_running()) { + kprobes_inc_nmissed_count(p); + } else { + unsigned long orig_ip = instruction_pointer(regs); + + instruction_pointer_set(regs, ip); + + __this_cpu_write(current_kprobe, p); + kcb->kprobe_status = KPROBE_HIT_ACTIVE; + if (!p->pre_handler || !p->pre_handler(p, regs)) { + /* + * Emulate singlestep (and also recover regs->pc) + * as if there is a nop + */ + instruction_pointer_set(regs, + (unsigned long)p->addr + MCOUNT_INSN_SIZE); + if (unlikely(p->post_handler)) { + kcb->kprobe_status = KPROBE_HIT_SSDONE; + p->post_handler(p, regs, 0); + } + instruction_pointer_set(regs, orig_ip); + } + + /* + * If pre_handler returns !0, it changes regs->pc. We have to + * skip emulating post_handler. + */ + __this_cpu_write(current_kprobe, NULL); + } +} +NOKPROBE_SYMBOL(kprobe_ftrace_handler); + +int arch_prepare_kprobe_ftrace(struct kprobe *p) +{ + p->ainsn.api.insn = NULL; + return 0; +} -- 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:[~2020-12-17 16:05 UTC|newest] Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-12-17 16:01 [PATCH v5 0/9] Add k/uprobe & fentry & error_injection supported guoren 2020-12-17 16:01 ` guoren 2020-12-17 16:01 ` [PATCH v5 1/9] RISC-V: Implement ptrace regs and stack API guoren 2020-12-17 16:01 ` guoren 2020-12-17 16:01 ` [PATCH v5 2/9] riscv: Fixup compile error BUILD_BUG_ON failed guoren 2020-12-17 16:01 ` guoren 2020-12-17 16:01 ` [PATCH v5 3/9] riscv: Fixup wrong ftrace remove cflag guoren 2020-12-17 16:01 ` guoren 2020-12-17 16:01 ` [PATCH v5 4/9] riscv: Fixup patch_text panic in ftrace guoren 2020-12-17 16:01 ` guoren 2020-12-22 20:26 ` Atish Patra 2020-12-22 20:26 ` Atish Patra 2020-12-17 16:01 ` [PATCH v5 5/9] riscv: Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT guoren 2020-12-17 16:01 ` guoren 2020-12-17 16:01 ` [PATCH v5 6/9] riscv: Add kprobes supported guoren 2020-12-17 16:01 ` guoren 2020-12-17 16:01 ` guoren [this message] 2020-12-17 16:01 ` [PATCH v5 7/9] riscv: Add KPROBES_ON_FTRACE supported guoren 2020-12-17 16:01 ` [PATCH v5 8/9] riscv: Add uprobes supported guoren 2020-12-17 16:01 ` guoren 2020-12-17 16:01 ` [PATCH v5 9/9] riscv: Add support for function error injection guoren 2020-12-17 16:01 ` guoren 2021-01-12 19:18 ` [PATCH v5 0/9] Add k/uprobe & fentry & error_injection supported Palmer Dabbelt 2021-01-12 19:18 ` Palmer Dabbelt
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