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 da8ec1e8e0648..cc9fbcedb3646 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) {