On Tue, 25 Feb 2025 17:26:03 -0500 Steven Rostedt <[email protected]> wrote:
> From: Sven Schnelle <[email protected]> > > Wire up the code to print function arguments in the function graph > tracer. This functionality can be enabled/disabled during runtime with > options/funcgraph-args. > > Example usage: > > 6) | dummy_xmit [dummy](skb = 0x8887c100, dev = 0x872ca000) { > 6) | consume_skb(skb = 0x8887c100) { > 6) | skb_release_head_state(skb = 0x8887c100) { > 6) 0.178 us | sock_wfree(skb = 0x8887c100) > 6) 0.627 us | } > > Cc: Masami Hiramatsu <[email protected]> > Cc: Mark Rutland <[email protected]> > Cc: Mathieu Desnoyers <[email protected]> > Cc: Andrew Morton <[email protected]> > Cc: Paul Walmsley <[email protected]> > Cc: Palmer Dabbelt <[email protected]> > Cc: Albert Ou <[email protected]> > Cc: Guo Ren <[email protected]> > Cc: Donglin Peng <[email protected]> > Cc: Zheng Yejian <[email protected]> > Link: https://lore.kernel.org/[email protected] > Co-developed-by: Steven Rostedt (Google) <[email protected]> > Signed-off-by: Sven Schnelle <[email protected]> > Signed-off-by: Steven Rostedt (Google) <[email protected]> > --- > kernel/trace/Kconfig | 6 ++ > kernel/trace/trace.h | 1 + > kernel/trace/trace_entries.h | 7 +- > kernel/trace/trace_functions_graph.c | 143 +++++++++++++++++++++------ > 4 files changed, 122 insertions(+), 35 deletions(-) > > diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig > index 60412c1012ef..033fba0633cf 100644 > --- a/kernel/trace/Kconfig > +++ b/kernel/trace/Kconfig > @@ -268,6 +268,12 @@ config FUNCTION_TRACE_ARGS > depends on HAVE_FUNCTION_ARG_ACCESS_API > depends on DEBUG_INFO_BTF > default y > + help > + If supported with function argument access API and BTF, then > + the function tracer and function graph tracer will support printing > + of function arguments. This feature is off by default, and can be > + enabled via the trace option func-args (for the function tracer) and > + funcgraph-args (for the function graph tracer) > > config DYNAMIC_FTRACE > bool "enable/disable function tracing dynamically" > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h > index 9c21ba45b7af..6963cd83b6da 100644 > --- a/kernel/trace/trace.h > +++ b/kernel/trace/trace.h > @@ -897,6 +897,7 @@ static __always_inline bool ftrace_hash_empty(struct > ftrace_hash *hash) > #define TRACE_GRAPH_PRINT_RETVAL 0x800 > #define TRACE_GRAPH_PRINT_RETVAL_HEX 0x1000 > #define TRACE_GRAPH_PRINT_RETADDR 0x2000 > +#define TRACE_GRAPH_ARGS 0x4000 > #define TRACE_GRAPH_PRINT_FILL_SHIFT 28 > #define TRACE_GRAPH_PRINT_FILL_MASK (0x3 << TRACE_GRAPH_PRINT_FILL_SHIFT) > > diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h > index fbfb396905a6..77a8ba3bc1e3 100644 > --- a/kernel/trace/trace_entries.h > +++ b/kernel/trace/trace_entries.h > @@ -72,17 +72,18 @@ FTRACE_ENTRY_REG(function, ftrace_entry, > ); > > /* Function call entry */ > -FTRACE_ENTRY_PACKED(funcgraph_entry, ftrace_graph_ent_entry, > +FTRACE_ENTRY(funcgraph_entry, ftrace_graph_ent_entry, > > TRACE_GRAPH_ENT, > > F_STRUCT( > __field_struct( struct ftrace_graph_ent, graph_ent > ) > __field_packed( unsigned long, graph_ent, func > ) > - __field_packed( int, graph_ent, depth > ) > + __field_packed( unsigned long, graph_ent, depth > ) > + __dynamic_array(unsigned long, args > ) > ), > > - F_printk("--> %ps (%d)", (void *)__entry->func, __entry->depth) > + F_printk("--> %ps (%lu)", (void *)__entry->func, __entry->depth) > ); > > #ifdef CONFIG_FUNCTION_GRAPH_RETADDR > diff --git a/kernel/trace/trace_functions_graph.c > b/kernel/trace/trace_functions_graph.c > index 136c750b0b4d..406b21472bde 100644 > --- a/kernel/trace/trace_functions_graph.c > +++ b/kernel/trace/trace_functions_graph.c > @@ -70,6 +70,10 @@ static struct tracer_opt trace_opts[] = { > #ifdef CONFIG_FUNCTION_GRAPH_RETADDR > /* Display function return address ? */ > { TRACER_OPT(funcgraph-retaddr, TRACE_GRAPH_PRINT_RETADDR) }, > +#endif > +#ifdef CONFIG_FUNCTION_TRACE_ARGS > + /* Display function arguments ? */ > + { TRACER_OPT(funcgraph-args, TRACE_GRAPH_ARGS) }, > #endif > /* Include sleep time (scheduled out) between entry and return */ > { TRACER_OPT(sleep-time, TRACE_GRAPH_SLEEP_TIME) }, > @@ -110,25 +114,41 @@ static void > print_graph_duration(struct trace_array *tr, unsigned long long duration, > struct trace_seq *s, u32 flags); > > -int __trace_graph_entry(struct trace_array *tr, > - struct ftrace_graph_ent *trace, > - unsigned int trace_ctx) > +static int __graph_entry(struct trace_array *tr, struct ftrace_graph_ent > *trace, > + unsigned int trace_ctx, struct ftrace_regs *fregs) > { > struct ring_buffer_event *event; > struct trace_buffer *buffer = tr->array_buffer.buffer; > struct ftrace_graph_ent_entry *entry; > + int size; > > - event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_ENT, > - sizeof(*entry), trace_ctx); > + /* If fregs is defined, add FTRACE_REGS_MAX_ARGS long size words */ > + size = sizeof(*entry) + (FTRACE_REGS_MAX_ARGS * !!fregs * sizeof(long)); Is `!!fregs` always 1 if fregs != NULL? (seems to depend on compiler) Others looks good to me. Reviewed-by: Masami Hiramatsu (Google) <[email protected]> Thank you, > + > + event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_ENT, size, > trace_ctx); > if (!event) > return 0; > - entry = ring_buffer_event_data(event); > - entry->graph_ent = *trace; > + > + entry = ring_buffer_event_data(event); > + entry->graph_ent = *trace; > + > + if (fregs) { > + for (int i = 0; i < FTRACE_REGS_MAX_ARGS; i++) > + entry->args[i] = ftrace_regs_get_argument(fregs, i); > + } > + > trace_buffer_unlock_commit_nostack(buffer, event); > > return 1; > } > > +int __trace_graph_entry(struct trace_array *tr, > + struct ftrace_graph_ent *trace, > + unsigned int trace_ctx) > +{ > + 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, > @@ -174,9 +194,9 @@ struct fgraph_times { > unsigned long long sleeptime; /* may be optional! */ > }; > > -int trace_graph_entry(struct ftrace_graph_ent *trace, > - struct fgraph_ops *gops, > - struct ftrace_regs *fregs) > +static int graph_entry(struct ftrace_graph_ent *trace, > + struct fgraph_ops *gops, > + struct ftrace_regs *fregs) > { > unsigned long *task_var = fgraph_get_task_var(gops); > struct trace_array *tr = gops->private; > @@ -246,7 +266,7 @@ int trace_graph_entry(struct ftrace_graph_ent *trace, > unsigned long retaddr = > ftrace_graph_top_ret_addr(current); > ret = __trace_graph_retaddr_entry(tr, trace, trace_ctx, > retaddr); > } else { > - ret = __trace_graph_entry(tr, trace, trace_ctx); > + ret = __graph_entry(tr, trace, trace_ctx, fregs); > } > } > preempt_enable_notrace(); > @@ -254,6 +274,20 @@ int trace_graph_entry(struct ftrace_graph_ent *trace, > return ret; > } > > +int trace_graph_entry(struct ftrace_graph_ent *trace, > + struct fgraph_ops *gops, > + struct ftrace_regs *fregs) > +{ > + return graph_entry(trace, gops, NULL); > +} > + > +static int trace_graph_entry_args(struct ftrace_graph_ent *trace, > + struct fgraph_ops *gops, > + struct ftrace_regs *fregs) > +{ > + return graph_entry(trace, gops, fregs); > +} > + > static void > __trace_graph_function(struct trace_array *tr, > unsigned long ip, unsigned int trace_ctx) > @@ -418,7 +452,10 @@ static int graph_trace_init(struct trace_array *tr) > { > int ret; > > - tr->gops->entryfunc = trace_graph_entry; > + if (tracer_flags_is_set(TRACE_GRAPH_ARGS)) > + tr->gops->entryfunc = trace_graph_entry_args; > + else > + tr->gops->entryfunc = trace_graph_entry; > > if (tracing_thresh) > tr->gops->retfunc = trace_graph_thresh_return; > @@ -775,7 +812,7 @@ static void print_graph_retaddr(struct trace_seq *s, > struct fgraph_retaddr_ent_e > > static void print_graph_retval(struct trace_seq *s, struct > ftrace_graph_ent_entry *entry, > struct ftrace_graph_ret *graph_ret, void *func, > - u32 opt_flags, u32 trace_flags) > + u32 opt_flags, u32 trace_flags, int args_size) > { > unsigned long err_code = 0; > unsigned long retval = 0; > @@ -809,7 +846,14 @@ static void print_graph_retval(struct trace_seq *s, > struct ftrace_graph_ent_entr > if (entry->ent.type != TRACE_GRAPH_RETADDR_ENT) > print_retaddr = false; > > - trace_seq_printf(s, "%ps();", func); > + trace_seq_printf(s, "%ps", func); > + > + if (args_size >= FTRACE_REGS_MAX_ARGS * sizeof(long)) { > + print_function_args(s, entry->args, (unsigned > long)func); > + trace_seq_putc(s, ';'); > + } else > + trace_seq_puts(s, "();"); > + > if (print_retval || print_retaddr) > trace_seq_puts(s, " /*"); > else > @@ -836,7 +880,8 @@ static void print_graph_retval(struct trace_seq *s, > struct ftrace_graph_ent_entr > > #else > > -#define print_graph_retval(_seq, _ent, _ret, _func, _opt_flags, > _trace_flags) do {} while (0) > +#define print_graph_retval(_seq, _ent, _ret, _func, _opt_flags, > _trace_flags, args_size) \ > + do {} while (0) > > #endif > > @@ -852,10 +897,14 @@ print_graph_entry_leaf(struct trace_iterator *iter, > struct ftrace_graph_ret *graph_ret; > struct ftrace_graph_ent *call; > unsigned long long duration; > + unsigned long ret_func; > unsigned long func; > + int args_size; > int cpu = iter->cpu; > int i; > > + args_size = iter->ent_size - offsetof(struct ftrace_graph_ent_entry, > args); > + > graph_ret = &ret_entry->ret; > call = &entry->graph_ent; > duration = ret_entry->rettime - ret_entry->calltime; > @@ -887,16 +936,25 @@ print_graph_entry_leaf(struct trace_iterator *iter, > for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) > trace_seq_putc(s, ' '); > > + ret_func = graph_ret->func + iter->tr->text_delta; > + > /* > * Write out the function return value or return address > */ > if (flags & (__TRACE_GRAPH_PRINT_RETVAL | __TRACE_GRAPH_PRINT_RETADDR)) > { > print_graph_retval(s, entry, graph_ret, > (void *)graph_ret->func + > iter->tr->text_delta, > - flags, tr->trace_flags); > + flags, tr->trace_flags, args_size); > } else { > - trace_seq_printf(s, "%ps();\n", (void *)func); > + 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); > + trace_seq_putc(s, ';'); > + } else > + trace_seq_puts(s, "();"); > } > + trace_seq_printf(s, "\n"); > > print_graph_irq(iter, graph_ret->func, TRACE_GRAPH_RET, > cpu, iter->ent->pid, flags); > @@ -913,6 +971,7 @@ print_graph_entry_nested(struct trace_iterator *iter, > struct fgraph_data *data = iter->private; > struct trace_array *tr = iter->tr; > unsigned long func; > + int args_size; > int i; > > if (data) { > @@ -937,7 +996,17 @@ print_graph_entry_nested(struct trace_iterator *iter, > > func = call->func + iter->tr->text_delta; > > - trace_seq_printf(s, "%ps() {", (void *)func); > + trace_seq_printf(s, "%ps", (void *)func); > + > + 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); > + else > + trace_seq_puts(s, "()"); > + > + trace_seq_puts(s, " {"); > + > if (flags & __TRACE_GRAPH_PRINT_RETADDR && > entry->ent.type == TRACE_GRAPH_RETADDR_ENT) > print_graph_retaddr(s, (struct fgraph_retaddr_ent_entry *)entry, > @@ -1107,21 +1176,38 @@ print_graph_entry(struct ftrace_graph_ent_entry > *field, struct trace_seq *s, > struct trace_iterator *iter, u32 flags) > { > struct fgraph_data *data = iter->private; > - struct ftrace_graph_ent *call = &field->graph_ent; > + struct ftrace_graph_ent *call; > struct ftrace_graph_ret_entry *leaf_ret; > static enum print_line_t ret; > int cpu = iter->cpu; > + /* > + * print_graph_entry() may consume the current event, > + * thus @field may become invalid, so we need to save it. > + * sizeof(struct ftrace_graph_ent_entry) is very small, > + * 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)]; > + > + /* The ent_size is expected to be as big as the entry */ > + if (iter->ent_size > sizeof(save_buf)) > + iter->ent_size = sizeof(save_buf); > + > + entry = (void *)save_buf; > + memcpy(entry, field, iter->ent_size); > + > + call = &entry->graph_ent; > > if (check_irq_entry(iter, flags, call->func, call->depth)) > return TRACE_TYPE_HANDLED; > > print_graph_prologue(iter, s, TRACE_GRAPH_ENT, call->func, flags); > > - leaf_ret = get_return_for_leaf(iter, field); > + leaf_ret = get_return_for_leaf(iter, entry); > if (leaf_ret) > - ret = print_graph_entry_leaf(iter, field, leaf_ret, s, flags); > + ret = print_graph_entry_leaf(iter, entry, leaf_ret, s, flags); > else > - ret = print_graph_entry_nested(iter, field, s, cpu, flags); > + ret = print_graph_entry_nested(iter, entry, s, cpu, flags); > > if (data) { > /* > @@ -1195,7 +1281,8 @@ print_graph_return(struct ftrace_graph_ret_entry > *retentry, struct trace_seq *s, > * funcgraph-retval option is enabled. > */ > if (flags & __TRACE_GRAPH_PRINT_RETVAL) { > - print_graph_retval(s, NULL, trace, (void *)func, flags, > tr->trace_flags); > + print_graph_retval(s, NULL, trace, (void *)func, flags, > + tr->trace_flags, 0); > } else { > /* > * If the return function does not have a matching entry, > @@ -1323,16 +1410,8 @@ print_graph_function_flags(struct trace_iterator > *iter, u32 flags) > > switch (entry->type) { > case TRACE_GRAPH_ENT: { > - /* > - * print_graph_entry() may consume the current event, > - * thus @field may become invalid, so we need to save it. > - * sizeof(struct ftrace_graph_ent_entry) is very small, > - * it can be safely saved at the stack. > - */ > - struct ftrace_graph_ent_entry saved; > trace_assign_type(field, entry); > - saved = *field; > - return print_graph_entry(&saved, s, iter, flags); > + return print_graph_entry(field, s, iter, flags); > } > #ifdef CONFIG_FUNCTION_GRAPH_RETADDR > case TRACE_GRAPH_RETADDR_ENT: { > -- > 2.47.2 > > -- Masami Hiramatsu (Google) <[email protected]>
