Commit 76fe0337 authored by Sven Schnelle's avatar Sven Schnelle Committed by Steven Rostedt (Google)
Browse files

ftrace: Add arguments to function tracer 

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: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Co-developed-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: default avatarSven Schnelle <svens@linux.ibm.com>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent c7a60a73

kernel/trace/trace.c

+12 −2
Original line number Diff line number Diff line
@@ -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);

kernel/trace/trace.h

+3 −1
Original line number Diff line number Diff line
@@ -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,

kernel/trace/trace_entries.h

+3 −2
Original line number Diff line number Diff line
@@ -63,6 +63,7 @@ FTRACE_ENTRY_REG(function, ftrace_entry, 
	F_STRUCT(

		__field_fn(	unsigned long,		ip		)

		__field_fn(	unsigned long,		parent_ip	)

		__dynamic_array( unsigned long,		args		)

	),



	F_printk(" %ps <-- %ps",

kernel/trace/trace_functions.c

+41 −5
Original line number Diff line number Diff line
@@ -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 */

};

kernel/trace/trace_irqsoff.c

+9 −3
Original line number Diff line number Diff line
@@ -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)

{