From patchwork Mon Dec 23 20:13:49 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 13919222 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 004231D2B2A; Mon, 23 Dec 2024 20:14:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734984891; cv=none; b=kR8gSnJjEYmKPcjod25gjbcjjUXO1r4xnssLhvMlOz1O4vTkuGPm0mvpyz1KbL/ns0TwzE2CtMe76ZInNGwZ8bzraLCSSnipVSV3BWhX/cHBveFB50bJWkcSjh5jQ1xkG/Hc8OBAGszRkTXEjB2SFn/BYM9oRNWcwwdCRqDCvH8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734984891; c=relaxed/simple; bh=F9Qeor6i09OxsqNXiesUh4VTpe1QxUZXNk8YJX4Z+rE=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=ZKTtF5+yDtUPhooBFFTWYl+Hh/VxeB/bl0wqlmAViMrKfSb3S0EJG8sB7F+p/ekVX2o+Q3DZXj0WvsW0fNeaqd0Ls0KDBMHSVlzjQZwQlLlOktk8CgiIUCw1YkXFUT3qCStMEW8FnvJKdnZXExqn26E/+Z7wMA/sYyCohCP10jY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7FE13C4CEE0; Mon, 23 Dec 2024 20:14:50 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.98) (envelope-from ) id 1tPoq6-0000000Dg9H-0v4s; Mon, 23 Dec 2024 15:15:42 -0500 Message-ID: <20241223201542.067076254@goodmis.org> User-Agent: quilt/0.68 Date: Mon, 23 Dec 2024 15:13:49 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Sven Schnelle , Paul Walmsley , Palmer Dabbelt , Albert Ou , Guo Ren , Donglin Peng , Zheng Yejian , bpf@vger.kernel.org Subject: [PATCH v2 2/4] ftrace: Add support for function argument to graph tracer References: <20241223201347.609298489@goodmis.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Sven Schnelle 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 | } Co-developed-by: Steven Rostedt (Google) Signed-off-by: Sven Schnelle Signed-off-by: Steven Rostedt (Google) --- Changes since v1: https://lore.kernel.org/20240904065908.1009086-7-svens@linux.ibm.com - Record just FTRACE_REGS_MAX_ARGS into the ring buffer and not the entire ftrace_regs structure, as that structure should be opaque from generic code. - Make the function graph entry event have a dynamic size, so that an array of arguments may be added in the ring buffer after it. kernel/trace/Kconfig | 6 ++ kernel/trace/trace.h | 1 + kernel/trace/trace_entries.h | 7 +- kernel/trace/trace_functions_graph.c | 147 +++++++++++++++++++++------ 4 files changed, 125 insertions(+), 36 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 ad9f008d7dd7..6f67bbc17bed 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -887,6 +887,7 @@ 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 82fd174ebbe0..254491b545c3 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 d0e4f412c298..c8eda9bebdf4 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -12,6 +12,8 @@ #include #include #include +#include +#include #include "trace.h" #include "trace_output.h" @@ -70,6 +72,10 @@ 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 +116,41 @@ 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)); + + 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 +196,9 @@ 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; @@ -248,7 +270,7 @@ int trace_graph_entry(struct ftrace_graph_ent *trace, 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); } else { ret = 0; } @@ -259,6 +281,20 @@ 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) @@ -423,7 +459,10 @@ 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; @@ -780,7 +819,7 @@ 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; @@ -814,7 +853,14 @@ 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 @@ -836,12 +882,13 @@ static void print_graph_retval(struct trace_seq *s, struct ftrace_graph_ent_entr } if (!entry || print_retval || print_retaddr) - trace_seq_puts(s, " */\n"); + trace_seq_puts(s, " */"); } #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 @@ -857,10 +904,14 @@ 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 = graph_ret->rettime - graph_ret->calltime; @@ -892,16 +943,25 @@ 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); @@ -918,6 +978,7 @@ 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) { @@ -942,7 +1003,17 @@ 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, @@ -1112,21 +1183,38 @@ 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) { /* @@ -1197,7 +1285,8 @@ print_graph_return(struct ftrace_graph_ret *trace, 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, @@ -1325,16 +1414,8 @@ 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: {