[PATCH] ftrace: Fix function name for trampoline

[Tatsuya S]

The issue that unrelated function name is shown on stack trace like
following even though it should be trampoline code address is caused by
the creation of trampoline code in the area where .init.text section
of module was freed after module is loaded.

bash-1344    [002] .....    43.644608: <stack trace>
  => (MODULE INIT FUNCTION)
  => vfs_write
  => ksys_write
  => do_syscall_64
  => entry_SYSCALL_64_after_hwframe

To resolve this, when function address of stack trace entry is in
trampoline, output without looking up symbol name.

Signed-off-by: Tatsuya S <tatsuya.s2862@xxxxxxxxx>
---
 kernel/trace/trace_output.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 868f2f912f28..32a0858373e2 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -1246,6 +1246,11 @@ static enum print_line_t trace_stack_print(struct trace_iterator *iter,
 			break;
 
 		trace_seq_puts(s, " => ");
+		if (is_ftrace_trampoline((*p) + delta)) {
+			trace_seq_printf(s, "0x%08lx", (*p) + delta);
+			trace_seq_putc(s, '\n');
+			continue;
+		}
 		seq_print_ip_sym(s, (*p) + delta, flags);
 		trace_seq_putc(s, '\n');
 	}
-- 
2.46.2