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An optimized build such as:
make -C tools/perf CLANG=1 CC=clang EXTRA_CFLAGS="-O3
will turn the dereference operation into a ud2 instruction, raising a
SIGILL rather than a SIGSEGV. Use raise(..) for correctness and clarity.
Similar issues were addressed in Numfor Mbiziwo-Tiapo's patch:
https://lkml.org/lkml/2019/7/8/1234
Committer testing:
Before:
[root@quaco ~]# perf test hooks
55: perf hooks : Ok
[root@quaco ~]# perf test -v hooks
55: perf hooks :
--- start ---
test child forked, pid 17092
SIGSEGV is observed as expected, try to recover.
Fatal error (SEGFAULT) in perf hook 'test'
test child finished with 0
---- end ----
perf hooks: Ok
[root@quaco ~]#
After:
[root@quaco ~]# perf test hooks
55: perf hooks : Ok
[root@quaco ~]# perf test -v hooks
55: perf hooks :
--- start ---
test child forked, pid 17909
SIGSEGV is observed as expected, try to recover.
Fatal error (SEGFAULT) in perf hook 'test'
test child finished with 0
---- end ----
perf hooks: Ok
[root@quaco ~]#
Fixes: a074865e60 ("perf tools: Introduce perf hooks")
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lore.kernel.org/lkml/20190925195924.152834-2-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
48 lines
988 B
C
48 lines
988 B
C
// SPDX-License-Identifier: GPL-2.0
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#include <signal.h>
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#include <stdlib.h>
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#include "tests.h"
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#include "debug.h"
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#include "perf-hooks.h"
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static void sigsegv_handler(int sig __maybe_unused)
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{
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pr_debug("SIGSEGV is observed as expected, try to recover.\n");
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perf_hooks__recover();
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signal(SIGSEGV, SIG_DFL);
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raise(SIGSEGV);
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exit(-1);
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}
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static void the_hook(void *_hook_flags)
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{
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int *hook_flags = _hook_flags;
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*hook_flags = 1234;
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/* Generate a segfault, test perf_hooks__recover */
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raise(SIGSEGV);
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}
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int test__perf_hooks(struct test *test __maybe_unused, int subtest __maybe_unused)
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{
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int hook_flags = 0;
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signal(SIGSEGV, sigsegv_handler);
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perf_hooks__set_hook("test", the_hook, &hook_flags);
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perf_hooks__invoke_test();
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/* hook is triggered? */
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if (hook_flags != 1234) {
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pr_debug("Setting failed: %d (%p)\n", hook_flags, &hook_flags);
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return TEST_FAIL;
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}
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/* the buggy hook is removed? */
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if (perf_hooks__get_hook("test"))
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return TEST_FAIL;
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return TEST_OK;
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}
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