Em Fri, Sep 11, 2020 at 03:00:05PM +0200, Jiri Olsa escreveu:
> 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
Thanks, tested and applied.
- Arnaldo
> Cc: Wang Nan <wangn...@huawei.com>
> Fixes: 8fd34e1cce18 ("perf test: Improve bp_signal")
> Signed-off-by: Jiri Olsa <jo...@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
>
--
- Arnaldo
