| Message ID | 20241021071454.34610-2-tatsuya.s2862@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 6ce5a6f0a07d37cc377df08a8d8a9c283420f323 |
| Headers | show |
| Series | [v4] tracing: Fix function name for trampoline | expand |
On Mon, 21 Oct 2024 07:14:53 +0000 Tatsuya S <tatsuya.s2862@gmail.com> wrote: > The issue that unrelated function name is shown on stack trace like > following even though it should be trampoline code address is caused by > the creation of trampoline code in the area where .init.text section > of module was freed after module is loaded. > > bash-1344 [002] ..... 43.644608: <stack trace> > => (MODULE INIT FUNCTION) > => vfs_write > => ksys_write > => do_syscall_64 > => entry_SYSCALL_64_after_hwframe > > To resolve this, when function address of stack trace entry is in > trampoline, output without looking up symbol name. > This looks good to me. Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Thank you, > Signed-off-by: Tatsuya S <tatsuya.s2862@gmail.com> > --- > V3 -> V4: Change header file to define FTRACE_TRAMPOLINE_MARKER. > Rename category name of commit message. > V2 -> V3: Instead of saving the trampoline address, marker was introduced. > V1 -> V2: Instead of checking trampoline when displaying "trace" results, > it stores trampoline when generating the stacktrace entry. > > kernel/trace/trace.c | 33 +++++++++++++++++++++++++-------- > kernel/trace/trace.h | 7 +++++++ > kernel/trace/trace_output.c | 4 ++++ > 3 files changed, 36 insertions(+), 8 deletions(-) > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index a8f52b6527ca..3d86937da610 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -988,7 +988,8 @@ static inline void trace_access_lock_init(void) > #endif > > #ifdef CONFIG_STACKTRACE > -static void __ftrace_trace_stack(struct trace_buffer *buffer, > +static void __ftrace_trace_stack(struct trace_array *tr, > + struct trace_buffer *buffer, > unsigned int trace_ctx, > int skip, struct pt_regs *regs); > static inline void ftrace_trace_stack(struct trace_array *tr, > @@ -997,7 +998,8 @@ static inline void ftrace_trace_stack(struct trace_array *tr, > int skip, struct pt_regs *regs); > > #else > -static inline void __ftrace_trace_stack(struct trace_buffer *buffer, > +static inline void __ftrace_trace_stack(struct trace_array *tr, > + struct trace_buffer *buffer, > unsigned int trace_ctx, > int skip, struct pt_regs *regs) > { > @@ -2928,7 +2930,8 @@ struct ftrace_stacks { > static DEFINE_PER_CPU(struct ftrace_stacks, ftrace_stacks); > static DEFINE_PER_CPU(int, ftrace_stack_reserve); > > -static void __ftrace_trace_stack(struct trace_buffer *buffer, > +static void __ftrace_trace_stack(struct trace_array *tr, > + struct trace_buffer *buffer, > unsigned int trace_ctx, > int skip, struct pt_regs *regs) > { > @@ -2975,6 +2978,20 @@ static void __ftrace_trace_stack(struct trace_buffer *buffer, > nr_entries = stack_trace_save(fstack->calls, size, skip); > } > > +#ifdef CONFIG_DYNAMIC_FTRACE > + /* Mark entry of stack trace as trampoline code */ > + if (tr->ops && tr->ops->trampoline) { > + unsigned long tramp_start = tr->ops->trampoline; > + unsigned long tramp_end = tramp_start + tr->ops->trampoline_size; > + unsigned long *calls = fstack->calls; > + > + for (int i = 0; i < nr_entries; i++) { > + if (calls[i] >= tramp_start && calls[i] < tramp_end) > + calls[i] = FTRACE_TRAMPOLINE_MARKER; > + } > + } > +#endif > + > event = __trace_buffer_lock_reserve(buffer, TRACE_STACK, > struct_size(entry, caller, nr_entries), > trace_ctx); > @@ -3005,7 +3022,7 @@ static inline void ftrace_trace_stack(struct trace_array *tr, > if (!(tr->trace_flags & TRACE_ITER_STACKTRACE)) > return; > > - __ftrace_trace_stack(buffer, trace_ctx, skip, regs); > + __ftrace_trace_stack(tr, buffer, trace_ctx, skip, regs); > } > > void __trace_stack(struct trace_array *tr, unsigned int trace_ctx, > @@ -3014,7 +3031,7 @@ void __trace_stack(struct trace_array *tr, unsigned int trace_ctx, > struct trace_buffer *buffer = tr->array_buffer.buffer; > > if (rcu_is_watching()) { > - __ftrace_trace_stack(buffer, trace_ctx, skip, NULL); > + __ftrace_trace_stack(tr, buffer, trace_ctx, skip, NULL); > return; > } > > @@ -3031,7 +3048,7 @@ void __trace_stack(struct trace_array *tr, unsigned int trace_ctx, > return; > > ct_irq_enter_irqson(); > - __ftrace_trace_stack(buffer, trace_ctx, skip, NULL); > + __ftrace_trace_stack(tr, buffer, trace_ctx, skip, NULL); > ct_irq_exit_irqson(); > } > > @@ -3048,8 +3065,8 @@ void trace_dump_stack(int skip) > /* Skip 1 to skip this function. */ > skip++; > #endif > - __ftrace_trace_stack(printk_trace->array_buffer.buffer, > - tracing_gen_ctx(), skip, NULL); > + __ftrace_trace_stack(printk_trace, printk_trace->array_buffer.buffer, > + tracing_gen_ctx(), skip, NULL); > } > EXPORT_SYMBOL_GPL(trace_dump_stack); > > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h > index c866991b9c78..30d6675c78cf 100644 > --- a/kernel/trace/trace.h > +++ b/kernel/trace/trace.h > @@ -2176,4 +2176,11 @@ static inline int rv_init_interface(void) > } > #endif > > +/* > + * This is used only to distinguish > + * function address from trampoline code. > + * So this value has no meaning. > + */ > +#define FTRACE_TRAMPOLINE_MARKER ((unsigned long) INT_MAX) > + > #endif /* _LINUX_KERNEL_TRACE_H */ > diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c > index 868f2f912f28..c14573e5a903 100644 > --- a/kernel/trace/trace_output.c > +++ b/kernel/trace/trace_output.c > @@ -1246,6 +1246,10 @@ static enum print_line_t trace_stack_print(struct trace_iterator *iter, > break; > > trace_seq_puts(s, " => "); > + if ((*p) == FTRACE_TRAMPOLINE_MARKER) { > + trace_seq_puts(s, "[FTRACE TRAMPOLINE]\n"); > + continue; > + } > seq_print_ip_sym(s, (*p) + delta, flags); > trace_seq_putc(s, '\n'); > } > -- > 2.47.0 >
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index a8f52b6527ca..3d86937da610 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -988,7 +988,8 @@ static inline void trace_access_lock_init(void) #endif #ifdef CONFIG_STACKTRACE -static void __ftrace_trace_stack(struct trace_buffer *buffer, +static void __ftrace_trace_stack(struct trace_array *tr, + struct trace_buffer *buffer, unsigned int trace_ctx, int skip, struct pt_regs *regs); static inline void ftrace_trace_stack(struct trace_array *tr, @@ -997,7 +998,8 @@ static inline void ftrace_trace_stack(struct trace_array *tr, int skip, struct pt_regs *regs); #else -static inline void __ftrace_trace_stack(struct trace_buffer *buffer, +static inline void __ftrace_trace_stack(struct trace_array *tr, + struct trace_buffer *buffer, unsigned int trace_ctx, int skip, struct pt_regs *regs) { @@ -2928,7 +2930,8 @@ struct ftrace_stacks { static DEFINE_PER_CPU(struct ftrace_stacks, ftrace_stacks); static DEFINE_PER_CPU(int, ftrace_stack_reserve); -static void __ftrace_trace_stack(struct trace_buffer *buffer, +static void __ftrace_trace_stack(struct trace_array *tr, + struct trace_buffer *buffer, unsigned int trace_ctx, int skip, struct pt_regs *regs) { @@ -2975,6 +2978,20 @@ static void __ftrace_trace_stack(struct trace_buffer *buffer, nr_entries = stack_trace_save(fstack->calls, size, skip); } +#ifdef CONFIG_DYNAMIC_FTRACE + /* Mark entry of stack trace as trampoline code */ + if (tr->ops && tr->ops->trampoline) { + unsigned long tramp_start = tr->ops->trampoline; + unsigned long tramp_end = tramp_start + tr->ops->trampoline_size; + unsigned long *calls = fstack->calls; + + for (int i = 0; i < nr_entries; i++) { + if (calls[i] >= tramp_start && calls[i] < tramp_end) + calls[i] = FTRACE_TRAMPOLINE_MARKER; + } + } +#endif + event = __trace_buffer_lock_reserve(buffer, TRACE_STACK, struct_size(entry, caller, nr_entries), trace_ctx); @@ -3005,7 +3022,7 @@ static inline void ftrace_trace_stack(struct trace_array *tr, if (!(tr->trace_flags & TRACE_ITER_STACKTRACE)) return; - __ftrace_trace_stack(buffer, trace_ctx, skip, regs); + __ftrace_trace_stack(tr, buffer, trace_ctx, skip, regs); } void __trace_stack(struct trace_array *tr, unsigned int trace_ctx, @@ -3014,7 +3031,7 @@ void __trace_stack(struct trace_array *tr, unsigned int trace_ctx, struct trace_buffer *buffer = tr->array_buffer.buffer; if (rcu_is_watching()) { - __ftrace_trace_stack(buffer, trace_ctx, skip, NULL); + __ftrace_trace_stack(tr, buffer, trace_ctx, skip, NULL); return; } @@ -3031,7 +3048,7 @@ void __trace_stack(struct trace_array *tr, unsigned int trace_ctx, return; ct_irq_enter_irqson(); - __ftrace_trace_stack(buffer, trace_ctx, skip, NULL); + __ftrace_trace_stack(tr, buffer, trace_ctx, skip, NULL); ct_irq_exit_irqson(); } @@ -3048,8 +3065,8 @@ void trace_dump_stack(int skip) /* Skip 1 to skip this function. */ skip++; #endif - __ftrace_trace_stack(printk_trace->array_buffer.buffer, - tracing_gen_ctx(), skip, NULL); + __ftrace_trace_stack(printk_trace, printk_trace->array_buffer.buffer, + tracing_gen_ctx(), skip, NULL); } EXPORT_SYMBOL_GPL(trace_dump_stack); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index c866991b9c78..30d6675c78cf 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -2176,4 +2176,11 @@ static inline int rv_init_interface(void) } #endif +/* + * This is used only to distinguish + * function address from trampoline code. + * So this value has no meaning. + */ +#define FTRACE_TRAMPOLINE_MARKER ((unsigned long) INT_MAX) + #endif /* _LINUX_KERNEL_TRACE_H */ diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c index 868f2f912f28..c14573e5a903 100644 --- a/kernel/trace/trace_output.c +++ b/kernel/trace/trace_output.c @@ -1246,6 +1246,10 @@ static enum print_line_t trace_stack_print(struct trace_iterator *iter, break; trace_seq_puts(s, " => "); + if ((*p) == FTRACE_TRAMPOLINE_MARKER) { + trace_seq_puts(s, "[FTRACE TRAMPOLINE]\n"); + continue; + } seq_print_ip_sym(s, (*p) + delta, flags); trace_seq_putc(s, '\n'); }
The issue that unrelated function name is shown on stack trace like following even though it should be trampoline code address is caused by the creation of trampoline code in the area where .init.text section of module was freed after module is loaded. bash-1344 [002] ..... 43.644608: <stack trace> => (MODULE INIT FUNCTION) => vfs_write => ksys_write => do_syscall_64 => entry_SYSCALL_64_after_hwframe To resolve this, when function address of stack trace entry is in trampoline, output without looking up symbol name. Signed-off-by: Tatsuya S <tatsuya.s2862@gmail.com> --- V3 -> V4: Change header file to define FTRACE_TRAMPOLINE_MARKER. Rename category name of commit message. V2 -> V3: Instead of saving the trampoline address, marker was introduced. V1 -> V2: Instead of checking trampoline when displaying "trace" results, it stores trampoline when generating the stacktrace entry. kernel/trace/trace.c | 33 +++++++++++++++++++++++++-------- kernel/trace/trace.h | 7 +++++++ kernel/trace/trace_output.c | 4 ++++ 3 files changed, 36 insertions(+), 8 deletions(-)