Messages in this thread | | | Subject | Re: [PATCH v5 10/10] LoongArch/ftrace: Fix unwind state when option func_stack_trace | From | Qing Zhang <> | Date | Fri, 28 Oct 2022 13:27:16 +0800 |
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On 2022/10/28 上午10:56, Huacai Chen wrote: > Hi, Qing, > > Can this patch be squashed to a previous one? > ok, I'll combine this patch with the previous patch.
Thanks - Qing
> Huacai > > On Mon, Sep 19, 2022 at 11:19 AM Qing Zhang <zhangqing@loongson.cn> wrote: >> >> Ftrace plays like function head exception, prologue analysis will stop soon >> because PC is at entry. >> >> 90000000004c5a54 <callee>: >> 90000000004c5a54: 03400000 andi $zero, $zero, 0x0 ==>move t0, ra >> 90000000004c5a58: 03400000 andi $zero, $zero, 0x0 ==>bl callsite >> ==>90000000004c5a5c: 02fcc063 addi.d $sp, $sp, -208(0xf30) >> ... >> >> When encountering ftrace_call, save trace function ra at PT_ERA, save >> parent ra at PT_R1, At this time, pc is the position after the two nops >> of callee. There is no conventional prologue operation between this >> position and the function entry, so we need to reset the first flag to >> make the caller continue to unwind. >> >> testing method: >> echo path_openat > ./set_ftrace_filter >> echo 1 > ./options/func_stack_trace >> echo function > ./current_tracer >> >> Reported-by: Jeff Xie <xiehuan09@gmail.com> >> Tested-by: Jinyang He <hejinyang@loongson.cn> >> Tested-by: Jeff Xie <xiehuan09@gmail.com> >> Signed-off-by: Qing Zhang <zhangqing@loongson.cn> >> --- >> arch/loongarch/include/asm/unwind.h | 2 +- >> arch/loongarch/kernel/unwind_prologue.c | 35 +++++++++++++++++++++---- >> 2 files changed, 31 insertions(+), 6 deletions(-) >> >> diff --git a/arch/loongarch/include/asm/unwind.h b/arch/loongarch/include/asm/unwind.h >> index f66b07c3e6a1..f2b52b9ea93d 100644 >> --- a/arch/loongarch/include/asm/unwind.h >> +++ b/arch/loongarch/include/asm/unwind.h >> @@ -20,7 +20,7 @@ struct unwind_state { >> char type; /* UNWINDER_XXX */ >> struct stack_info stack_info; >> struct task_struct *task; >> - bool first, error; >> + bool first, error, is_ftrace; >> int graph_idx; >> unsigned long sp, pc, ra; >> }; >> diff --git a/arch/loongarch/kernel/unwind_prologue.c b/arch/loongarch/kernel/unwind_prologue.c >> index f77f3b6f3f06..4fb4923b68cc 100644 >> --- a/arch/loongarch/kernel/unwind_prologue.c >> +++ b/arch/loongarch/kernel/unwind_prologue.c >> @@ -14,9 +14,7 @@ unsigned long unwind_get_return_address(struct unwind_state *state) >> >> if (unwind_done(state)) >> return 0; >> - else if (state->type) >> - return state->pc; >> - else if (state->first) >> + else if (state->type || state->first) >> return state->pc; >> >> return *(unsigned long *)(state->sp); >> @@ -42,16 +40,41 @@ static bool unwind_by_guess(struct unwind_state *state) >> return false; >> } >> >> +static inline void unwind_state_fixup(struct unwind_state *state) >> +{ >> +#ifdef CONFIG_FUNCTION_TRACER >> + static unsigned long ftrace_case = (unsigned long)ftrace_call + 4; >> + >> + if (state->pc == ftrace_case) >> + state->is_ftrace = true; >> +#endif >> +} >> + >> static bool unwind_by_prologue(struct unwind_state *state) >> { >> struct stack_info *info = &state->stack_info; >> union loongarch_instruction *ip, *ip_end; >> unsigned long frame_size = 0, frame_ra = -1; >> unsigned long size, offset, pc = state->pc; >> + struct pt_regs *regs; >> >> if (state->sp >= info->end || state->sp < info->begin) >> return false; >> >> + if (state->is_ftrace) { >> + /* >> + * As we meet ftrace_regs_entry, reset first flag like first doing >> + * tracing, Prologue analysis will stop soon because PC is at entry. >> + */ >> + regs = (struct pt_regs *)state->sp; >> + state->pc = regs->csr_era; >> + state->ra = regs->regs[1]; >> + state->sp = regs->regs[3]; >> + state->first = true; >> + state->is_ftrace = false; >> + return true; >> + } >> + >> if (!kallsyms_lookup_size_offset(pc, &size, &offset)) >> return false; >> >> @@ -97,7 +120,7 @@ static bool unwind_by_prologue(struct unwind_state *state) >> >> state->pc = *(unsigned long *)(state->sp + frame_ra); >> state->sp = state->sp + frame_size; >> - return !!__kernel_text_address(state->pc); >> + goto out; >> >> first: >> state->first = false; >> @@ -106,7 +129,9 @@ static bool unwind_by_prologue(struct unwind_state *state) >> >> state->pc = state->ra; >> >> - return !!__kernel_text_address(state->ra); >> +out: >> + unwind_state_fixup(state); >> + return !!__kernel_text_address(state->pc); >> } >> >> void unwind_start(struct unwind_state *state, struct task_struct *task, >> -- >> 2.36.1 >>
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