On Wed, 12 Nov 2025 11:43:33 +0800 Donglin Peng <[email protected]> wrote:
> From: Donglin Peng <[email protected]> > > Currently, the funcgraph-args and funcgraph-retaddr features are mutually > exclusive. > This patch resolves this limitation by modifying funcgraph-retaddr to adopt > the same > implementation approach as funcgraph-args, specifically by storing the return > address > in the first entry of the args array. > > As a result, both features now coexist seamlessly and function as intended. > > To verify the change, use perf to trace vfs_write with both options enabled: > > Before: > # perf ftrace -G vfs_write --graph-opts args,retaddr > ...... > 0) | down_read() { /* <-n_tty_write+0xa3/0x540 */ > 0) 0.075 us | __cond_resched(); /* <-down_read+0x12/0x160 */ > 0) 0.079 us | preempt_count_add(); /* <-down_read+0x3b/0x160 */ > 0) 0.077 us | preempt_count_sub(); /* <-down_read+0x8b/0x160 */ > 0) 0.754 us | } > > After: > # perf ftrace -G vfs_write --graph-opts args,retaddr > ...... > 0) | down_read(sem=0xffff8880100bea78) { /* > <-n_tty_write+0xa3/0x540 */ > 0) 0.075 us | __cond_resched(); /* <-down_read+0x12/0x160 */ > 0) 0.079 us | preempt_count_add(val=1); /* <-down_read+0x3b/0x160 */ > 0) 0.077 us | preempt_count_sub(val=1); /* <-down_read+0x8b/0x160 */ > 0) 0.754 us | } > > Cc: Steven Rostedt (Google) <[email protected]> > Cc: Sven Schnelle <[email protected]> > Cc: Masami Hiramatsu <[email protected]> > Signed-off-by: Donglin Peng <[email protected]> Looks good to me except for a few nits, but it's a style issue. Acked-by: Masami Hiramatsu (Google) <[email protected]> Thank you, > --- > v3: > - Replace min() with min_t() to improve type safety and maintainability > - Keep only one Signed-off-by for cleaner attribution > - Code refactoring for improved readability > > v2: > - Preserve retaddr event functionality (suggested by Steven) > - Store the retaddr in args[0] (suggested by Steven) > - Refactor implementation logic and commit message clarity > --- > include/linux/ftrace.h | 11 -- > kernel/trace/trace.h | 4 - > kernel/trace/trace_entries.h | 6 +- > kernel/trace/trace_functions_graph.c | 145 ++++++++++++--------------- > 4 files changed, 69 insertions(+), 97 deletions(-) > > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h > index 7ded7df6e9b5..88cb54d73bdb 100644 > --- a/include/linux/ftrace.h > +++ b/include/linux/ftrace.h > @@ -1129,17 +1129,6 @@ struct ftrace_graph_ent { > int depth; > } __packed; > > -/* > - * Structure that defines an entry function trace with retaddr. > - * It's already packed but the attribute "packed" is needed > - * to remove extra padding at the end. > - */ > -struct fgraph_retaddr_ent { > - unsigned long func; /* Current function */ > - int depth; > - unsigned long retaddr; /* Return address */ > -} __packed; > - > /* > * Structure that defines a return function trace. > * It's already packed but the attribute "packed" is needed > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h > index 85eabb454bee..9fac291b913a 100644 > --- a/kernel/trace/trace.h > +++ b/kernel/trace/trace.h > @@ -955,10 +955,6 @@ extern void graph_trace_close(struct trace_iterator > *iter); > extern int __trace_graph_entry(struct trace_array *tr, > struct ftrace_graph_ent *trace, > unsigned int trace_ctx); > -extern int __trace_graph_retaddr_entry(struct trace_array *tr, > - struct ftrace_graph_ent *trace, > - unsigned int trace_ctx, > - unsigned long retaddr); > extern void __trace_graph_return(struct trace_array *tr, > struct ftrace_graph_ret *trace, > unsigned int trace_ctx, > diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h > index de294ae2c5c5..593a74663c65 100644 > --- a/kernel/trace/trace_entries.h > +++ b/kernel/trace/trace_entries.h > @@ -95,14 +95,14 @@ FTRACE_ENTRY_PACKED(fgraph_retaddr_entry, > fgraph_retaddr_ent_entry, > TRACE_GRAPH_RETADDR_ENT, > > F_STRUCT( > - __field_struct( struct fgraph_retaddr_ent, graph_ent > ) > + __field_struct( struct ftrace_graph_ent, graph_ent > ) > __field_packed( unsigned long, graph_ent, func > ) > __field_packed( unsigned int, graph_ent, depth > ) > - __field_packed( unsigned long, graph_ent, retaddr > ) > + __dynamic_array(unsigned long, args > ) > ), > > F_printk("--> %ps (%u) <- %ps", (void *)__entry->func, __entry->depth, > - (void *)__entry->retaddr) > + (void *)__entry->args[0]) > ); > > #else > diff --git a/kernel/trace/trace_functions_graph.c > b/kernel/trace/trace_functions_graph.c > index a7f4b9a47a71..f31eeeffbb2d 100644 > --- a/kernel/trace/trace_functions_graph.c > +++ b/kernel/trace/trace_functions_graph.c > @@ -16,6 +16,15 @@ > #include "trace.h" > #include "trace_output.h" > > +#ifdef CONFIG_FUNCTION_GRAPH_RETADDR > +#define HAVE_RETADDR 1 > +#define ARGS_OFFS(args_size) \ > + ((args_size) > FTRACE_REGS_MAX_ARGS * sizeof(long) ? 1 : 0) > +#else > +#define HAVE_RETADDR 0 > +#define ARGS_OFFS(args_size) 0 > +#endif > + > /* When set, irq functions will be ignored */ > static int ftrace_graph_skip_irqs; > > @@ -27,21 +36,25 @@ struct fgraph_cpu_data { > unsigned long enter_funcs[FTRACE_RETFUNC_DEPTH]; > }; > > +/* > + * fgraph_retaddr_ent_entry and ftrace_graph_ent_entry share layout, ent > + * member repurposed for storage > + */ > struct fgraph_ent_args { > struct ftrace_graph_ent_entry ent; > - /* Force the sizeof of args[] to have FTRACE_REGS_MAX_ARGS entries */ > - unsigned long args[FTRACE_REGS_MAX_ARGS]; > + /* > + * Force the sizeof of args[] to have (FTRACE_REGS_MAX_ARGS + > HAVE_RETADDR) > + * entries with the first entry storing the return address for > + * TRACE_GRAPH_RETADDR_ENT. > + */ > + unsigned long args[FTRACE_REGS_MAX_ARGS + HAVE_RETADDR]; > }; > > struct fgraph_data { > struct fgraph_cpu_data __percpu *cpu_data; > > /* Place to preserve last processed entry. */ > - union { > - struct fgraph_ent_args ent; > - /* TODO allow retaddr to have args */ > - struct fgraph_retaddr_ent_entry rent; > - }; > + struct fgraph_ent_args ent; > struct ftrace_graph_ret_entry ret; > int failed; > int cpu; > @@ -127,22 +140,43 @@ static int __graph_entry(struct trace_array *tr, struct > ftrace_graph_ent *trace, > struct ring_buffer_event *event; > struct trace_buffer *buffer = tr->array_buffer.buffer; > struct ftrace_graph_ent_entry *entry; > - int size; > + unsigned long retaddr = 0; > + int size = sizeof(*entry); > + int type = TRACE_GRAPH_ENT; > + bool store_args = false; > + int nr_args = 0, args_offs = 0; > + > + if (tracer_flags_is_set(TRACE_GRAPH_PRINT_RETADDR)) { > + retaddr = ftrace_graph_top_ret_addr(current); > + type = TRACE_GRAPH_RETADDR_ENT; > + nr_args += 1; > + } > > /* If fregs is defined, add FTRACE_REGS_MAX_ARGS long size words */ > - size = sizeof(*entry) + (FTRACE_REGS_MAX_ARGS * !!fregs * sizeof(long)); > + if (tracer_flags_is_set(TRACE_GRAPH_ARGS)) { > + store_args = !!fregs; > + if (store_args) > + nr_args += FTRACE_REGS_MAX_ARGS; > + } > > - event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_ENT, size, > trace_ctx); > + size += nr_args * sizeof(long); > + event = trace_buffer_lock_reserve(buffer, type, size, trace_ctx); > if (!event) > return 0; > > entry = ring_buffer_event_data(event); > entry->graph_ent = *trace; > > + /* Store the retaddr in args[0] */ > + if (type == TRACE_GRAPH_RETADDR_ENT) { > + entry->args[0] = retaddr; > + args_offs += 1; > + } > + > #ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API > - if (fregs) { > + if (store_args) { > for (int i = 0; i < FTRACE_REGS_MAX_ARGS; i++) > - entry->args[i] = ftrace_regs_get_argument(fregs, i); > + entry->args[i + args_offs] = > ftrace_regs_get_argument(fregs, i); > } > #endif > > @@ -158,38 +192,6 @@ int __trace_graph_entry(struct trace_array *tr, > return __graph_entry(tr, trace, trace_ctx, NULL); > } > > -#ifdef CONFIG_FUNCTION_GRAPH_RETADDR > -int __trace_graph_retaddr_entry(struct trace_array *tr, > - struct ftrace_graph_ent *trace, > - unsigned int trace_ctx, > - unsigned long retaddr) > -{ > - struct ring_buffer_event *event; > - struct trace_buffer *buffer = tr->array_buffer.buffer; > - struct fgraph_retaddr_ent_entry *entry; > - > - event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_RETADDR_ENT, > - sizeof(*entry), trace_ctx); > - if (!event) > - return 0; > - entry = ring_buffer_event_data(event); > - entry->graph_ent.func = trace->func; > - entry->graph_ent.depth = trace->depth; > - entry->graph_ent.retaddr = retaddr; > - trace_buffer_unlock_commit_nostack(buffer, event); > - > - return 1; > -} > -#else > -int __trace_graph_retaddr_entry(struct trace_array *tr, > - struct ftrace_graph_ent *trace, > - unsigned int trace_ctx, > - unsigned long retaddr) > -{ > - return 1; > -} > -#endif > - > static inline int ftrace_graph_ignore_irqs(void) > { > if (!ftrace_graph_skip_irqs || trace_recursion_test(TRACE_IRQ_BIT)) > @@ -211,7 +213,6 @@ static int graph_entry(struct ftrace_graph_ent *trace, > struct trace_array *tr = gops->private; > struct fgraph_times *ftimes; > unsigned int trace_ctx; > - int ret = 0; > > if (*task_var & TRACE_GRAPH_NOTRACE) > return 0; > @@ -262,15 +263,7 @@ static int graph_entry(struct ftrace_graph_ent *trace, > return 1; > > trace_ctx = tracing_gen_ctx(); > - if (IS_ENABLED(CONFIG_FUNCTION_GRAPH_RETADDR) && > - tracer_flags_is_set(TRACE_GRAPH_PRINT_RETADDR)) { > - unsigned long retaddr = ftrace_graph_top_ret_addr(current); > - ret = __trace_graph_retaddr_entry(tr, trace, trace_ctx, > retaddr); > - } else { > - ret = __graph_entry(tr, trace, trace_ctx, fregs); > - } > - > - return ret; > + return __graph_entry(tr, trace, trace_ctx, fregs); > } > > int trace_graph_entry(struct ftrace_graph_ent *trace, > @@ -634,13 +627,9 @@ get_return_for_leaf(struct trace_iterator *iter, > * Save current and next entries for later reference > * if the output fails. > */ > - if (unlikely(curr->ent.type == > TRACE_GRAPH_RETADDR_ENT)) { > - data->rent = *(struct fgraph_retaddr_ent_entry > *)curr; > - } else { > - int size = min((int)sizeof(data->ent), > (int)iter->ent_size); > + int size = min_t(int, sizeof(data->ent), > iter->ent_size); > > - memcpy(&data->ent, curr, size); > - } > + memcpy(&data->ent, curr, size); > /* > * If the next event is not a return type, then > * we only care about what type it is. Otherwise we can > @@ -811,21 +800,21 @@ print_graph_duration(struct trace_array *tr, unsigned > long long duration, > > #ifdef CONFIG_FUNCTION_GRAPH_RETADDR > #define __TRACE_GRAPH_PRINT_RETADDR TRACE_GRAPH_PRINT_RETADDR > -static void print_graph_retaddr(struct trace_seq *s, struct > fgraph_retaddr_ent_entry *entry, > - u32 trace_flags, bool comment) > +static void print_graph_retaddr(struct trace_seq *s, unsigned long retaddr, > u32 trace_flags, > + bool comment) > { > if (comment) > trace_seq_puts(s, " /*"); > > trace_seq_puts(s, " <-"); > - seq_print_ip_sym(s, entry->graph_ent.retaddr, trace_flags | > TRACE_ITER_SYM_OFFSET); > + seq_print_ip_sym(s, retaddr, trace_flags | TRACE_ITER_SYM_OFFSET); > > if (comment) > trace_seq_puts(s, " */"); > } > #else > #define __TRACE_GRAPH_PRINT_RETADDR 0 > -#define print_graph_retaddr(_seq, _entry, _tflags, _comment) do { } > while (0) > +#define print_graph_retaddr(_seq, _retaddr, _tflags, _comment) > do { } while (0) > #endif > > #if defined(CONFIG_FUNCTION_GRAPH_RETVAL) || > defined(CONFIG_FUNCTION_GRAPH_RETADDR) > @@ -869,10 +858,12 @@ static void print_graph_retval(struct trace_seq *s, > struct ftrace_graph_ent_entr > trace_seq_printf(s, "%ps", func); > > if (args_size >= FTRACE_REGS_MAX_ARGS * sizeof(long)) { > - print_function_args(s, entry->args, (unsigned > long)func); > + print_function_args(s, entry->args + > ARGS_OFFS(args_size), > + (unsigned long)func); > trace_seq_putc(s, ';'); > - } else > + } else { nit: you don't need to add braces for a single line block. > trace_seq_puts(s, "();"); > + } > > if (print_retval || print_retaddr) > trace_seq_puts(s, " /*"); > @@ -882,8 +873,7 @@ static void print_graph_retval(struct trace_seq *s, > struct ftrace_graph_ent_entr > } > > if (print_retaddr) > - print_graph_retaddr(s, (struct fgraph_retaddr_ent_entry *)entry, > - trace_flags, false); > + print_graph_retaddr(s, entry->args[0], trace_flags, false); > > if (print_retval) { > if (hex_format || (err_code == 0)) > @@ -964,10 +954,12 @@ print_graph_entry_leaf(struct trace_iterator *iter, > trace_seq_printf(s, "%ps", (void *)ret_func); > > if (args_size >= FTRACE_REGS_MAX_ARGS * sizeof(long)) { > - print_function_args(s, entry->args, ret_func); > + print_function_args(s, entry->args + > ARGS_OFFS(args_size), > + ret_func); > trace_seq_putc(s, ';'); > - } else > + } else { Ditto. > trace_seq_puts(s, "();"); > + } > } > trace_seq_putc(s, '\n'); > > @@ -1016,7 +1008,7 @@ print_graph_entry_nested(struct trace_iterator *iter, > args_size = iter->ent_size - offsetof(struct ftrace_graph_ent_entry, > args); > > if (args_size >= FTRACE_REGS_MAX_ARGS * sizeof(long)) > - print_function_args(s, entry->args, func); > + print_function_args(s, entry->args + ARGS_OFFS(args_size), > func); > else > trace_seq_puts(s, "()"); > > @@ -1024,8 +1016,7 @@ print_graph_entry_nested(struct trace_iterator *iter, > > if (flags & __TRACE_GRAPH_PRINT_RETADDR && > entry->ent.type == TRACE_GRAPH_RETADDR_ENT) > - print_graph_retaddr(s, (struct fgraph_retaddr_ent_entry *)entry, > - tr->trace_flags, true); > + print_graph_retaddr(s, entry->args[0], tr->trace_flags, true); > trace_seq_putc(s, '\n'); > > if (trace_seq_has_overflowed(s)) > @@ -1202,7 +1193,7 @@ print_graph_entry(struct ftrace_graph_ent_entry *field, > struct trace_seq *s, > * it can be safely saved at the stack. > */ > struct ftrace_graph_ent_entry *entry; > - u8 save_buf[sizeof(*entry) + FTRACE_REGS_MAX_ARGS * sizeof(long)]; > + u8 save_buf[sizeof(*entry) + (FTRACE_REGS_MAX_ARGS + HAVE_RETADDR) * > sizeof(long)]; > > /* The ent_size is expected to be as big as the entry */ > if (iter->ent_size > sizeof(save_buf)) > @@ -1429,16 +1420,12 @@ print_graph_function_flags(struct trace_iterator > *iter, u32 flags) > trace_assign_type(field, entry); > return print_graph_entry(field, s, iter, flags); > } > -#ifdef CONFIG_FUNCTION_GRAPH_RETADDR > case TRACE_GRAPH_RETADDR_ENT: { > - struct fgraph_retaddr_ent_entry saved; > struct fgraph_retaddr_ent_entry *rfield; > > trace_assign_type(rfield, entry); > - saved = *rfield; > - return print_graph_entry((struct ftrace_graph_ent_entry > *)&saved, s, iter, flags); > + return print_graph_entry((typeof(field))rfield, s, iter, flags); > } > -#endif > case TRACE_GRAPH_RET: { > struct ftrace_graph_ret_entry *field; > trace_assign_type(field, entry); > -- > 2.34.1 > -- Masami Hiramatsu (Google) <[email protected]>
