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Message-ID: <20240904065908.1009086-7-svens@linux.ibm.com>
Date: Wed, 4 Sep 2024 08:59:00 +0200
From: Sven Schnelle <svens@...ux.ibm.com>
To: Steven Rostedt <rostedt@...dmis.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
bpf@...r.kernel.org
Subject: [PATCH 6/7] tracing: add support for function argument to graph tracer
Wire up the code to print function arguments in the function graph
tracer. This functionality can be enabled/disabled during compile
time by setting CONFIG_FUNCTION_TRACE_ARGS and 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 | }
Signed-off-by: Sven Schnelle <svens@...ux.ibm.com>
---
include/linux/ftrace.h | 1 +
kernel/trace/fgraph.c | 6 ++-
kernel/trace/trace_functions_graph.c | 74 ++++++++++++++--------------
3 files changed, 44 insertions(+), 37 deletions(-)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 56d91041ecd2..5d0ff66f8a70 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1010,6 +1010,7 @@ static inline void ftrace_init(void) { }
* to remove extra padding at the end.
*/
struct ftrace_graph_ent {
+ struct ftrace_regs regs;
unsigned long func; /* Current function */
int depth;
} __packed;
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index fa62ebfa0711..f4bb10c0aa52 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -614,7 +614,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
/* If the caller does not use ftrace, call this function. */
int function_graph_enter(unsigned long ret, unsigned long func,
unsigned long frame_pointer, unsigned long *retp,
- struct ftrace_regs *fregs)
+ struct ftrace_regs *fregs)
{
struct ftrace_graph_ent trace;
unsigned long bitmap = 0;
@@ -623,6 +623,10 @@ int function_graph_enter(unsigned long ret, unsigned long func,
trace.func = func;
trace.depth = ++current->curr_ret_depth;
+ if (IS_ENABLED(CONFIG_FUNCTION_TRACE_ARGS) && fregs)
+ trace.regs = *fregs;
+ else
+ memset(&trace.regs, 0, sizeof(struct ftrace_regs));
offset = ftrace_push_return_trace(ret, func, frame_pointer, retp, 0);
if (offset < 0)
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 13d0387ac6a6..be0cee52944a 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -12,6 +12,8 @@
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/fs.h>
+#include <linux/btf.h>
+#include <linux/bpf.h>
#include "trace.h"
#include "trace_output.h"
@@ -63,6 +65,9 @@ static struct tracer_opt trace_opts[] = {
{ TRACER_OPT(funcgraph-retval, TRACE_GRAPH_PRINT_RETVAL) },
/* Display function return value in hexadecimal format ? */
{ TRACER_OPT(funcgraph-retval-hex, TRACE_GRAPH_PRINT_RETVAL_HEX) },
+#endif
+#ifdef CONFIG_FUNCTION_TRACE_ARGS
+ { 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) },
@@ -653,7 +658,7 @@ print_graph_duration(struct trace_array *tr, unsigned long long duration,
#define __TRACE_GRAPH_PRINT_RETVAL TRACE_GRAPH_PRINT_RETVAL
static void print_graph_retval(struct trace_seq *s, unsigned long retval,
- bool leaf, void *func, bool hex_format)
+ bool hex_format)
{
unsigned long err_code = 0;
@@ -673,28 +678,17 @@ static void print_graph_retval(struct trace_seq *s, unsigned long retval,
err_code = 0;
done:
- if (leaf) {
- if (hex_format || (err_code == 0))
- trace_seq_printf(s, "%ps(); /* = 0x%lx */\n",
- func, retval);
- else
- trace_seq_printf(s, "%ps(); /* = %ld */\n",
- func, err_code);
- } else {
- if (hex_format || (err_code == 0))
- trace_seq_printf(s, "} /* %ps = 0x%lx */\n",
- func, retval);
- else
- trace_seq_printf(s, "} /* %ps = %ld */\n",
- func, err_code);
- }
+ if (hex_format || (err_code == 0))
+ trace_seq_printf(s, " /* = 0x%lx */", retval);
+ else
+ trace_seq_printf(s, " /* = %ld */", err_code);
}
#else
#define __TRACE_GRAPH_PRINT_RETVAL 0
-#define print_graph_retval(_seq, _retval, _leaf, _func, _format) do {} while (0)
+#define print_graph_retval(_seq, _retval, _format) do {} while (0)
#endif
@@ -741,16 +735,20 @@ print_graph_entry_leaf(struct trace_iterator *iter,
/* Function */
for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++)
trace_seq_putc(s, ' ');
+ trace_seq_printf(s, "%ps", (void *)graph_ret->func);
+ if (flags & TRACE_GRAPH_ARGS)
+ print_function_args(s, &call->regs, graph_ret->func);
+ else
+ trace_seq_puts(s, "();");
/*
* Write out the function return value if the option function-retval is
* enabled.
*/
if (flags & __TRACE_GRAPH_PRINT_RETVAL)
- print_graph_retval(s, graph_ret->retval, true, (void *)call->func,
- !!(flags & TRACE_GRAPH_PRINT_RETVAL_HEX));
- else
- trace_seq_printf(s, "%ps();\n", (void *)call->func);
+ print_graph_retval(s, graph_ret->retval,
+ !!(flags & TRACE_GRAPH_PRINT_RETVAL_HEX));
+ trace_seq_printf(s, "\n");
print_graph_irq(iter, graph_ret->func, TRACE_GRAPH_RET,
cpu, iter->ent->pid, flags);
@@ -788,7 +786,12 @@ print_graph_entry_nested(struct trace_iterator *iter,
for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++)
trace_seq_putc(s, ' ');
- trace_seq_printf(s, "%ps() {\n", (void *)call->func);
+ trace_seq_printf(s, "%ps", (void *)call->func);
+ if (flags & TRACE_GRAPH_ARGS)
+ print_function_args(s, &call->regs, call->func);
+ else
+ trace_seq_puts(s, "()");
+ trace_seq_printf(s, " {\n");
if (trace_seq_has_overflowed(s))
return TRACE_TYPE_PARTIAL_LINE;
@@ -1028,27 +1031,26 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++)
trace_seq_putc(s, ' ');
+ /*
+ * If the return function does not have a matching entry,
+ * then the entry was lost. Instead of just printing
+ * the '}' and letting the user guess what function this
+ * belongs to, write out the function name. Always do
+ * that if the funcgraph-tail option is enabled.
+ */
+ if (func_match && !(flags & TRACE_GRAPH_PRINT_TAIL))
+ trace_seq_puts(s, "}");
+ else
+ trace_seq_printf(s, "} /* %ps */", (void *)trace->func);
/*
* Always write out the function name and its return value if the
* function-retval option is enabled.
*/
if (flags & __TRACE_GRAPH_PRINT_RETVAL) {
- print_graph_retval(s, trace->retval, false, (void *)trace->func,
+ print_graph_retval(s, trace->retval,
!!(flags & TRACE_GRAPH_PRINT_RETVAL_HEX));
- } else {
- /*
- * If the return function does not have a matching entry,
- * then the entry was lost. Instead of just printing
- * the '}' and letting the user guess what function this
- * belongs to, write out the function name. Always do
- * that if the funcgraph-tail option is enabled.
- */
- if (func_match && !(flags & TRACE_GRAPH_PRINT_TAIL))
- trace_seq_puts(s, "}\n");
- else
- trace_seq_printf(s, "} /* %ps */\n", (void *)trace->func);
}
-
+ trace_seq_printf(s, "\n");
/* Overrun */
if (flags & TRACE_GRAPH_PRINT_OVERRUN)
trace_seq_printf(s, " (Overruns: %u)\n",
--
2.43.0
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