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function_graph: Enable funcgraph-args and funcgraph-retaddr to work simultaneously

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Currently, the funcgraph-args and funcgraph-retaddr features are
mutually exclusive. This patch resolves this limitation by allowing
funcgraph-retaddr to have an args array.

To verify the change, use perf to trace vfs_write with both options
enabled:

Before:
 # perf ftrace -G vfs_write --graph-opts args,retaddr
   ......
   down_read() { /* <-n_tty_write+0xa3/0x540 */
     __cond_resched(); /* <-down_read+0x12/0x160 */
     preempt_count_add(); /* <-down_read+0x3b/0x160 */
     preempt_count_sub(); /* <-down_read+0x8b/0x160 */
   }

After:
 # perf ftrace -G vfs_write --graph-opts args,retaddr
   ......
   down_read(sem=0xffff8880100bea78) { /* <-n_tty_write+0xa3/0x540 */
     __cond_resched(); /* <-down_read+0x12/0x160 */
     preempt_count_add(val=1); /* <-down_read+0x3b/0x160 */
     preempt_count_sub(val=1); /* <-down_read+0x8b/0x160 */
   }

Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Xiaoqin Zhang <zhangxiaoqin@xiaomi.com>
Link: https://patch.msgid.link/20251125093425.2563849-1-dolinux.peng@gmail.com
Signed-off-by: pengdonglin <pengdonglin@xiaomi.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
pengdonglin
2025-11-25 17:34:25 +08:00
committed by Steven Rostedt (Google)
parent 20e7168326
commit f83ac7544f
4 changed files with 80 additions and 37 deletions
Download Patch File Download Diff File Expand all files Collapse all files

71
kernel/trace/trace_functions_graph.c
View File

@@ -36,14 +36,19 @@ struct fgraph_ent_args {
unsigned long args[FTRACE_REGS_MAX_ARGS];
};
struct fgraph_retaddr_ent_args {
struct fgraph_retaddr_ent_entry ent;
/* Force the sizeof of args[] to have FTRACE_REGS_MAX_ARGS entries */
unsigned long args[FTRACE_REGS_MAX_ARGS];
};
struct fgraph_data {
struct fgraph_cpu_data __percpu *cpu_data;
/* Place to preserve last processed entry. */
union {
struct fgraph_ent_args ent;
/* TODO allow retaddr to have args */
struct fgraph_retaddr_ent_entry rent;
struct fgraph_retaddr_ent_args rent;
};
struct ftrace_graph_ret_entry ret;
int failed;
@@ -160,20 +165,32 @@ int __trace_graph_entry(struct trace_array *tr,
int __trace_graph_retaddr_entry(struct trace_array *tr,
struct ftrace_graph_ent *trace,
unsigned int trace_ctx,
unsigned long retaddr)
unsigned long retaddr,
struct ftrace_regs *fregs)
{
struct ring_buffer_event *event;
struct trace_buffer *buffer = tr->array_buffer.buffer;
struct fgraph_retaddr_ent_entry *entry;
int size;
/* 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_RETADDR_ENT,
sizeof(*entry), trace_ctx);
size, trace_ctx);
if (!event)
return 0;
entry = ring_buffer_event_data(event);
entry->graph_ent.func = trace->func;
entry->graph_ent.depth = trace->depth;
entry->graph_ent.retaddr = retaddr;
entry->graph_rent.ent = *trace;
entry->graph_rent.retaddr = retaddr;
#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
trace_buffer_unlock_commit_nostack(buffer, event);
return 1;
@@ -182,7 +199,8 @@ int __trace_graph_retaddr_entry(struct trace_array *tr,
int __trace_graph_retaddr_entry(struct trace_array *tr,
struct ftrace_graph_ent *trace,
unsigned int trace_ctx,
unsigned long retaddr)
unsigned long retaddr,
struct ftrace_regs *fregs)
{
return 1;
}
@@ -267,7 +285,8 @@ static int graph_entry(struct ftrace_graph_ent *trace,
if (IS_ENABLED(CONFIG_FUNCTION_GRAPH_RETADDR) &&
tracer_flags_is_set(tr, TRACE_GRAPH_PRINT_RETADDR)) {
unsigned long retaddr = ftrace_graph_top_ret_addr(current);
ret = __trace_graph_retaddr_entry(tr, trace, trace_ctx, retaddr);
ret = __trace_graph_retaddr_entry(tr, trace, trace_ctx,
retaddr, fregs);
} else {
ret = __graph_entry(tr, trace, trace_ctx, fregs);
}
@@ -654,13 +673,9 @@ get_return_for_leaf(struct trace_iterator *iter,
* Save current and next entries for later reference
* if the output fails.
*/
if (unlikely(curr->ent.type == TRACE_GRAPH_RETADDR_ENT)) {
data->rent = *(struct fgraph_retaddr_ent_entry *)curr;
} else {
int size = min((int)sizeof(data->ent), (int)iter->ent_size);
int size = min_t(int, sizeof(data->rent), iter->ent_size);
memcpy(&data->ent, curr, size);
}
memcpy(&data->rent, curr, size);
/*
* If the next event is not a return type, then
* we only care about what type it is. Otherwise we can
@@ -838,7 +853,7 @@ static void print_graph_retaddr(struct trace_seq *s, struct fgraph_retaddr_ent_e
trace_seq_puts(s, " /*");
trace_seq_puts(s, " <-");
seq_print_ip_sym_offset(s, entry->graph_ent.retaddr, trace_flags);
seq_print_ip_sym_offset(s, entry->graph_rent.retaddr, trace_flags);
if (comment)
trace_seq_puts(s, " */");
@@ -984,7 +999,7 @@ print_graph_entry_leaf(struct trace_iterator *iter,
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);
print_function_args(s, FGRAPH_ENTRY_ARGS(entry), ret_func);
trace_seq_putc(s, ';');
} else
trace_seq_puts(s, "();");
@@ -1036,7 +1051,7 @@ print_graph_entry_nested(struct trace_iterator *iter,
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);
print_function_args(s, FGRAPH_ENTRY_ARGS(entry), func);
else
trace_seq_puts(s, "()");
@@ -1218,11 +1233,14 @@ print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
/*
* 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.
* This function is shared by ftrace_graph_ent_entry and
* fgraph_retaddr_ent_entry, the size of the latter one
* is larger, but it is very small and can be safely saved
* at the stack.
*/
struct ftrace_graph_ent_entry *entry;
u8 save_buf[sizeof(*entry) + FTRACE_REGS_MAX_ARGS * sizeof(long)];
struct fgraph_retaddr_ent_entry *rentry;
u8 save_buf[sizeof(*rentry) + 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))
@@ -1451,12 +1469,17 @@ print_graph_function_flags(struct trace_iterator *iter, u32 flags)
}
#ifdef CONFIG_FUNCTION_GRAPH_RETADDR
case TRACE_GRAPH_RETADDR_ENT: {
struct fgraph_retaddr_ent_entry saved;
/*
* ftrace_graph_ent_entry and fgraph_retaddr_ent_entry have
* similar functions and memory layouts. The only difference
* is that the latter one has an extra retaddr member, so
* they can share most of the logic.
*/
struct fgraph_retaddr_ent_entry *rfield;
trace_assign_type(rfield, entry);
saved = *rfield;
return print_graph_entry((struct ftrace_graph_ent_entry *)&saved, s, iter, flags);
return print_graph_entry((struct ftrace_graph_ent_entry *)rfield,
s, iter, flags);
}
#endif
case TRACE_GRAPH_RET: {