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Subject[PATCH] perf test: Fix signal test inline assembly
Date
When compiling with DEBUG=1 on Fedora 32 I'm getting crash for
'perf test signal':

Program received signal SIGSEGV, Segmentation fault.
0x0000000000c68548 in __test_function ()
(gdb) bt
#0 0x0000000000c68548 in __test_function ()
#1 0x00000000004d62e9 in test_function () at tests/bp_signal.c:61
#2 0x00000000004d689a in test__bp_signal (test=0xa8e280 <generic_ ...
#3 0x00000000004b7d49 in run_test (test=0xa8e280 <generic_tests+1 ...
#4 0x00000000004b7e7f in test_and_print (t=0xa8e280 <generic_test ...
#5 0x00000000004b8927 in __cmd_test (argc=1, argv=0x7fffffffdce0, ...
...

It's caused by __test_function being in .bss section:

$ readelf -a ./perf | less
[Nr] Name Type Address Offset
Size EntSize Flags Link Info Align
...
[28] .bss NOBITS 0000000000c356a0 008346a0
00000000000511f8 0000000000000000 WA 0 0 32

$ nm perf | grep __test_function
0000000000c68548 B __test_function

I guess most of the time we're just lucky the inline asm ended up
in .text section, so making it specific explicit with push and pop
section cluases.

$ readelf -a ./perf | less
[Nr] Name Type Address Offset
Size EntSize Flags Link Info Align
...
[13] .text PROGBITS 0000000000431240 00031240
0000000000306faa 0000000000000000 AX 0 0 16

$ nm perf | grep __test_function
00000000004d62c8 T __test_function

Cc: Wang Nan <wangnan0@huawei.com>
Fixes: 8fd34e1cce18 ("perf test: Improve bp_signal")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
tools/perf/tests/bp_signal.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/perf/tests/bp_signal.c b/tools/perf/tests/bp_signal.c
index da8ec1e8e064..cc9fbcedb364 100644
--- a/tools/perf/tests/bp_signal.c
+++ b/tools/perf/tests/bp_signal.c
@@ -45,10 +45,13 @@ volatile long the_var;
#if defined (__x86_64__)
extern void __test_function(volatile long *ptr);
asm (
+ ".pushsection .text;"
".globl __test_function\n"
+ ".type __test_function, @function;"
"__test_function:\n"
"incq (%rdi)\n"
- "ret\n");
+ "ret\n"
+ ".popsection\n");
#else
static void __test_function(volatile long *ptr)
{
--
2.26.2
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