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ftrace: Add arguments to function tracer

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Wire up the code to print function arguments in the function tracer.
This functionality can be enabled/disabled during runtime with
options/func-args.

        ping-689     [004] b....    77.170220: dummy_xmit(skb = 0x82904800, dev = 0x882d0000) <-dev_hard_start_xmit

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Guo Ren <guoren@kernel.org>
Cc: Donglin Peng <dolinux.peng@gmail.com>
Cc: Zheng Yejian <zhengyejian@huaweicloud.com>
Link: https://lore.kernel.org/20250227185823.154996172@goodmis.org
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Co-developed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Sven Schnelle 2025-02-27 13:58:08 -05:00 committed by Steven Rostedt (Google)
parent c7a60a733c
commit 76fe0337c2
7 changed files with 85 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
kernel/trace/trace.c
View File

@ -2878,13 +2878,16 @@ trace_buffer_unlock_commit_nostack(struct trace_buffer *buffer,
void
trace_function(struct trace_array *tr, unsigned long ip, unsigned long
parent_ip, unsigned int trace_ctx)
parent_ip, unsigned int trace_ctx, struct ftrace_regs *fregs)
{
struct trace_buffer *buffer = tr->array_buffer.buffer;
struct ring_buffer_event *event;
struct ftrace_entry *entry;
int size = sizeof(*entry);
event = __trace_buffer_lock_reserve(buffer, TRACE_FN, sizeof(*entry),
size += FTRACE_REGS_MAX_ARGS * !!fregs * sizeof(long);
event = __trace_buffer_lock_reserve(buffer, TRACE_FN, size,
trace_ctx);
if (!event)
return;
@ -2892,6 +2895,13 @@ trace_function(struct trace_array *tr, unsigned long ip, unsigned long
entry->ip = ip;
entry->parent_ip = parent_ip;
#ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
if (fregs) {
for (int i = 0; i < FTRACE_REGS_MAX_ARGS; i++)
entry->args[i] = ftrace_regs_get_argument(fregs, i);
}
#endif
if (static_branch_unlikely(&trace_function_exports_enabled))
ftrace_exports(event, TRACE_EXPORT_FUNCTION);
__buffer_unlock_commit(buffer, event);

4
kernel/trace/trace.h
View File

@ -21,6 +21,7 @@
#include <linux/workqueue.h>
#include <linux/ctype.h>
#include <linux/once_lite.h>
#include <linux/ftrace_regs.h>
#include "pid_list.h"
@ -697,7 +698,8 @@ unsigned long trace_total_entries(struct trace_array *tr);
void trace_function(struct trace_array *tr,
unsigned long ip,
unsigned long parent_ip,
unsigned int trace_ctx);
unsigned int trace_ctx,
struct ftrace_regs *regs);
void trace_graph_function(struct trace_array *tr,
unsigned long ip,
unsigned long parent_ip,

5
kernel/trace/trace_entries.h
View File

@ -61,8 +61,9 @@ FTRACE_ENTRY_REG(function, ftrace_entry,
TRACE_FN,
F_STRUCT(
__field_fn( unsigned long, ip )
__field_fn( unsigned long, parent_ip )
__field_fn( unsigned long, ip )
__field_fn( unsigned long, parent_ip )
__dynamic_array( unsigned long, args )
),
F_printk(" %ps <-- %ps",

46
kernel/trace/trace_functions.c
View File

@ -25,6 +25,9 @@ static void
function_trace_call(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs);
static void
function_args_trace_call(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs);
static void
function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs);
static void
@ -42,9 +45,10 @@ enum {
TRACE_FUNC_NO_OPTS = 0x0, /* No flags set. */
TRACE_FUNC_OPT_STACK = 0x1,
TRACE_FUNC_OPT_NO_REPEATS = 0x2,
TRACE_FUNC_OPT_ARGS = 0x4,
/* Update this to next highest bit. */
TRACE_FUNC_OPT_HIGHEST_BIT = 0x4
TRACE_FUNC_OPT_HIGHEST_BIT = 0x8
};
#define TRACE_FUNC_OPT_MASK (TRACE_FUNC_OPT_HIGHEST_BIT - 1)
@ -114,6 +118,8 @@ static ftrace_func_t select_trace_function(u32 flags_val)
switch (flags_val & TRACE_FUNC_OPT_MASK) {
case TRACE_FUNC_NO_OPTS:
return function_trace_call;
case TRACE_FUNC_OPT_ARGS:
return function_args_trace_call;
case TRACE_FUNC_OPT_STACK:
return function_stack_trace_call;
case TRACE_FUNC_OPT_NO_REPEATS:
@ -220,7 +226,34 @@ function_trace_call(unsigned long ip, unsigned long parent_ip,
data = this_cpu_ptr(tr->array_buffer.data);
if (!atomic_read(&data->disabled))
trace_function(tr, ip, parent_ip, trace_ctx);
trace_function(tr, ip, parent_ip, trace_ctx, NULL);
ftrace_test_recursion_unlock(bit);
}
static void
function_args_trace_call(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs)
{
struct trace_array *tr = op->private;
struct trace_array_cpu *data;
unsigned int trace_ctx;
int bit;
int cpu;
if (unlikely(!tr->function_enabled))
return;
bit = ftrace_test_recursion_trylock(ip, parent_ip);
if (bit < 0)
return;
trace_ctx = tracing_gen_ctx();
cpu = smp_processor_id();
data = per_cpu_ptr(tr->array_buffer.data, cpu);
if (!atomic_read(&data->disabled))
trace_function(tr, ip, parent_ip, trace_ctx, fregs);
ftrace_test_recursion_unlock(bit);
}
@ -270,7 +303,7 @@ function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
if (likely(disabled == 1)) {
trace_ctx = tracing_gen_ctx_flags(flags);
trace_function(tr, ip, parent_ip, trace_ctx);
trace_function(tr, ip, parent_ip, trace_ctx, NULL);
#ifdef CONFIG_UNWINDER_FRAME_POINTER
if (ftrace_pids_enabled(op))
skip++;
@ -349,7 +382,7 @@ function_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
trace_ctx = tracing_gen_ctx_dec();
process_repeats(tr, ip, parent_ip, last_info, trace_ctx);
trace_function(tr, ip, parent_ip, trace_ctx);
trace_function(tr, ip, parent_ip, trace_ctx, NULL);
out:
ftrace_test_recursion_unlock(bit);
@ -389,7 +422,7 @@ function_stack_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
trace_ctx = tracing_gen_ctx_flags(flags);
process_repeats(tr, ip, parent_ip, last_info, trace_ctx);
trace_function(tr, ip, parent_ip, trace_ctx);
trace_function(tr, ip, parent_ip, trace_ctx, NULL);
__trace_stack(tr, trace_ctx, STACK_SKIP);
}
@ -403,6 +436,9 @@ static struct tracer_opt func_opts[] = {
{ TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
#endif
{ TRACER_OPT(func-no-repeats, TRACE_FUNC_OPT_NO_REPEATS) },
#ifdef CONFIG_FUNCTION_TRACE_ARGS
{ TRACER_OPT(func-args, TRACE_FUNC_OPT_ARGS) },
#endif
{ } /* Always set a last empty entry */
};

12
kernel/trace/trace_irqsoff.c
View File

@ -150,7 +150,7 @@ irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip,
trace_ctx = tracing_gen_ctx_flags(flags);
trace_function(tr, ip, parent_ip, trace_ctx);
trace_function(tr, ip, parent_ip, trace_ctx, fregs);
atomic_dec(&data->disabled);
}
@ -295,11 +295,17 @@ __trace_function(struct trace_array *tr,
if (is_graph(tr))
trace_graph_function(tr, ip, parent_ip, trace_ctx);
else
trace_function(tr, ip, parent_ip, trace_ctx);
trace_function(tr, ip, parent_ip, trace_ctx, NULL);
}
#else
#define __trace_function trace_function
static inline void
__trace_function(struct trace_array *tr,
unsigned long ip, unsigned long parent_ip,
unsigned int trace_ctx)
{
return trace_function(tr, ip, parent_ip, trace_ctx, NULL);
}
static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
{

18
kernel/trace/trace_output.c
View File

@ -1090,12 +1090,15 @@ enum print_line_t trace_nop_print(struct trace_iterator *iter, int flags,
}
static void print_fn_trace(struct trace_seq *s, unsigned long ip,
unsigned long parent_ip, long delta, int flags)
unsigned long parent_ip, long delta,
unsigned long *args, int flags)
{
ip += delta;
parent_ip += delta;
seq_print_ip_sym(s, ip, flags);
if (args)
print_function_args(s, args, ip);
if ((flags & TRACE_ITER_PRINT_PARENT) && parent_ip) {
trace_seq_puts(s, " <-");
@ -1109,10 +1112,19 @@ static enum print_line_t trace_fn_trace(struct trace_iterator *iter, int flags,
{
struct ftrace_entry *field;
struct trace_seq *s = &iter->seq;
unsigned long *args;
int args_size;
trace_assign_type(field, iter->ent);
print_fn_trace(s, field->ip, field->parent_ip, iter->tr->text_delta, flags);
args_size = iter->ent_size - offsetof(struct ftrace_entry, args);
if (args_size >= FTRACE_REGS_MAX_ARGS * sizeof(long))
args = field->args;
else
args = NULL;
print_fn_trace(s, field->ip, field->parent_ip, iter->tr->text_delta,
args, flags);
trace_seq_putc(s, '\n');
return trace_handle_return(s);
@ -1785,7 +1797,7 @@ trace_func_repeats_print(struct trace_iterator *iter, int flags,
trace_assign_type(field, iter->ent);
print_fn_trace(s, field->ip, field->parent_ip, iter->tr->text_delta, flags);
print_fn_trace(s, field->ip, field->parent_ip, iter->tr->text_delta, NULL, flags);
trace_seq_printf(s, " (repeats: %u, last_ts:", field->count);
trace_print_time(s, iter,
iter->ts - FUNC_REPEATS_GET_DELTA_TS(field));

4
kernel/trace/trace_sched_wakeup.c
View File

@ -242,7 +242,7 @@ wakeup_tracer_call(unsigned long ip, unsigned long parent_ip,
return;
local_irq_save(flags);
trace_function(tr, ip, parent_ip, trace_ctx);
trace_function(tr, ip, parent_ip, trace_ctx, fregs);
local_irq_restore(flags);
atomic_dec(&data->disabled);
@ -327,7 +327,7 @@ __trace_function(struct trace_array *tr,
if (is_graph(tr))
trace_graph_function(tr, ip, parent_ip, trace_ctx);
else
trace_function(tr, ip, parent_ip, trace_ctx);
trace_function(tr, ip, parent_ip, trace_ctx, NULL);
}
static int wakeup_flag_changed(struct trace_array *tr, u32 mask, int set)