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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 ...... down_read() { /* <-n_tty_write+0xa3/0x540 */ __cond_resched(); /* <-down_read+0x12/0x160 */ preempt_count_add(); /* <-down_read+0x3b/0x160 */ preempt_count_sub(); /* <-down_read+0x8b/0x160 */ } After: # perf ftrace -G vfs_write --graph-opts args,retaddr ...... down_read(sem=0xffff8880100bea78) { /* <-n_tty_write+0xa3/0x540 */ __cond_resched(); /* <-down_read+0x12/0x160 */ preempt_count_add(val=1); /* <-down_read+0x3b/0x160 */ preempt_count_sub(val=1); /* <-down_read+0x8b/0x160 */ } Cc: Steven Rostedt (Google) Cc: Sven Schnelle Cc: Masami Hiramatsu Signed-off-by: Donglin Peng Acked-by: Masami Hiramatsu (Google) --- v5: - Avoid unnecessary branch overhead by first verifying CONFIG_FUNCTION_GRAPH_RETADDR is enabled prior to testing the TRACE_GRAPH_PRINT_RETADDR flag v4: - Remove redundant TRACE_GRAPH_ARGS flag check - Eliminate unnecessary retaddr initialization - Resend to add missing add Acked-by tags 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 | 142 ++++++++++++--------------- 4 files changed, 66 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..fa2fb9a0a8ba 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 +140,40 @@ 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; + int size = sizeof(*entry); + int type = TRACE_GRAPH_ENT; + int nr_args = 0, args_offs = 0; + + if (IS_ENABLED(CONFIG_FUNCTION_GRAPH_RETADDR) && + 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 (!!fregs) + 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 (nr_args >= FTRACE_REGS_MAX_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 +189,6 @@ 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 +210,6 @@ 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 +260,7 @@ 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 +624,9 @@ 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 +797,21 @@ 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 +855,12 @@ 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 { trace_seq_puts(s, "();"); + } if (print_retval || print_retaddr) trace_seq_puts(s, " /*"); @@ -882,8 +870,7 @@ 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 +951,12 @@ 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 { trace_seq_puts(s, "();"); + } } trace_seq_putc(s, '\n'); @@ -1016,7 +1005,7 @@ 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 +1013,7 @@ 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 +1190,7 @@ 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 +1417,12 @@ 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