| Message ID | 1446182741-31019-4-git-send-email-takahiro.akashi@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
On 11/01/2015 05:00 PM, Jungseok Lee wrote: > On Oct 30, 2015, at 2:25 PM, AKASHI Takahiro wrote: > > Hi Akashi, > >> Function graph tracer modifies a return address (LR) in a stack frame >> to hook a function return. This will result in many useless entries >> (return_to_handler) showing up in a stack tracer's output. >> >> This patch replaces such entries with originals values preserved in >> current->ret_stack[]. >> >> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> >> --- >> arch/arm64/include/asm/ftrace.h | 2 ++ >> arch/arm64/kernel/stacktrace.c | 21 +++++++++++++++++++++ >> 2 files changed, 23 insertions(+) >> >> diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h >> index 2b43e20..b7d597c 100644 >> --- a/arch/arm64/include/asm/ftrace.h >> +++ b/arch/arm64/include/asm/ftrace.h >> @@ -29,6 +29,8 @@ struct dyn_arch_ftrace { >> >> extern unsigned long ftrace_graph_call; >> >> +extern void return_to_handler(void); >> + >> static inline unsigned long ftrace_call_adjust(unsigned long addr) >> { >> /* >> diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c >> index bc0689a..631c49d 100644 >> --- a/arch/arm64/kernel/stacktrace.c >> +++ b/arch/arm64/kernel/stacktrace.c >> @@ -17,6 +17,7 @@ >> */ >> #include <linux/kernel.h> >> #include <linux/export.h> >> +#include <linux/ftrace.h> >> #include <linux/sched.h> >> #include <linux/stacktrace.h> >> >> @@ -78,6 +79,9 @@ struct stack_trace_data { >> struct stack_trace *trace; >> unsigned int no_sched_functions; >> unsigned int skip; >> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER >> + unsigned int ret_stack_index; >> +#endif >> }; >> >> static int save_trace(struct stackframe *frame, void *d) >> @@ -86,6 +90,20 @@ static int save_trace(struct stackframe *frame, void *d) >> struct stack_trace *trace = data->trace; >> unsigned long addr = frame->pc; >> >> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER >> + if (addr == (unsigned long)return_to_handler - AARCH64_INSN_SIZE) { >> + /* >> + * This is a case where function graph tracer has >> + * modified a return address (LR) in a stack frame >> + * to hook a function return. >> + * So replace it to an original value. >> + */ >> + frame->pc = addr = >> + current->ret_stack[data->ret_stack_index--].ret >> + - AARCH64_INSN_SIZE; >> + } >> +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ >> + > > This hunk would be affected as the commit, "ARM64: unwind: Fix PC calculation", > e306dfd0, has been reverted. Yeah, we don't need apply this patch any more. The other patches in the series will not be affected. Thanks, -Takahiro AKASHI > Best Regards > Jungseok Lee > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h index 2b43e20..b7d597c 100644 --- a/arch/arm64/include/asm/ftrace.h +++ b/arch/arm64/include/asm/ftrace.h @@ -29,6 +29,8 @@ struct dyn_arch_ftrace { extern unsigned long ftrace_graph_call; +extern void return_to_handler(void); + static inline unsigned long ftrace_call_adjust(unsigned long addr) { /* diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index bc0689a..631c49d 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -17,6 +17,7 @@ */ #include <linux/kernel.h> #include <linux/export.h> +#include <linux/ftrace.h> #include <linux/sched.h> #include <linux/stacktrace.h> @@ -78,6 +79,9 @@ struct stack_trace_data { struct stack_trace *trace; unsigned int no_sched_functions; unsigned int skip; +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + unsigned int ret_stack_index; +#endif }; static int save_trace(struct stackframe *frame, void *d) @@ -86,6 +90,20 @@ static int save_trace(struct stackframe *frame, void *d) struct stack_trace *trace = data->trace; unsigned long addr = frame->pc; +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + if (addr == (unsigned long)return_to_handler - AARCH64_INSN_SIZE) { + /* + * This is a case where function graph tracer has + * modified a return address (LR) in a stack frame + * to hook a function return. + * So replace it to an original value. + */ + frame->pc = addr = + current->ret_stack[data->ret_stack_index--].ret + - AARCH64_INSN_SIZE; + } +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ + if (data->no_sched_functions && in_sched_functions(addr)) return 0; if (data->skip) { @@ -105,6 +123,9 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) data.trace = trace; data.skip = trace->skip; +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + data.ret_stack_index = current->curr_ret_stack; +#endif if (tsk != current) { data.no_sched_functions = 1;
Function graph tracer modifies a return address (LR) in a stack frame to hook a function return. This will result in many useless entries (return_to_handler) showing up in a stack tracer's output. This patch replaces such entries with originals values preserved in current->ret_stack[]. Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> --- arch/arm64/include/asm/ftrace.h | 2 ++ arch/arm64/kernel/stacktrace.c | 21 +++++++++++++++++++++ 2 files changed, 23 insertions(+) -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/