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Subject[PATCH 4.19 30/49] perf test: Fix the "signal" test inline assembly
Date
From: Jiri Olsa <jolsa@kernel.org>

[ Upstream commit 8a39e8c4d9baf65d88f66d49ac684df381e30055 ]

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 the symbol __test_function being in the ".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 the
".text" section, so making it specific explicit with push and pop
section clauses.

$ 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

Committer testing:

$ readelf -wi ~/bin/perf | grep producer -m1
<c> DW_AT_producer : (indirect string, offset: 0x254a): GNU C99 10.2.1 20200723 (Red Hat 10.2.1-1) -mtune=generic -march=x86-64 -ggdb3 -std=gnu99 -fno-omit-frame-pointer -funwind-tables -fstack-protector-all
^^^^^
^^^^^
^^^^^
$

Before:

$ perf test signal
20: Breakpoint overflow signal handler : FAILED!
$

After:

$ perf test signal
20: Breakpoint overflow signal handler : Ok
$

Fixes: 8fd34e1cce18 ("perf test: Improve bp_signal")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lore.kernel.org/lkml/20200911130005.1842138-1-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@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 6cf00650602ef..697423ce3bdfc 100644
--- a/tools/perf/tests/bp_signal.c
+++ b/tools/perf/tests/bp_signal.c
@@ -44,10 +44,13 @@ 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)
{
--
2.25.1


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