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From:   Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Date:   Mon, 8 Jul 2019 21:49:43 -0300
To:     Numfor Mbiziwo-Tiapo <nums@google.com>
Cc:     peterz@infradead.org, mingo@redhat.com,
        alexander.shishkin@linux.intel.com, jolsa@redhat.com,
        namhyung@kernel.org, songliubraving@fb.com, mbd@fb.com,
        linux-kernel@vger.kernel.org, irogers@google.com,
        eranian@google.com
Subject: Re: [PATCH] Fix perf-hooks test for sanitizers
Message-ID: <20190709004943.GA25880@kernel.org>
References: <20190708215928.167905-1-nums@google.com>
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Em Mon, Jul 08, 2019 at 02:59:28PM -0700, Numfor Mbiziwo-Tiapo escreveu:
> The perf-hooks test fails with Address Sanitizer and Memory
> Sanitizer builds because it purposefully generates a segfault.
> Checking if these sanitizers are active when running this test
> will allow the perf-hooks test to pass.
> 
> This can be replicated by running (from the tip directory):
> 
> make -C tools/perf USE_CLANG=1 EXTRA_CFLAGS="-fsanitize=address \
> -DADDRESS_SANITIZER=1"
> 
> then running tools/perf/perf test 55
> 
> Fix past to pass:
> The raised signal was changed from SIGSEGV to SIGILL to get the test 
> to pass on our local machines which use clang 4.

We still need a little bit more info, because I couldn't find libasan in
the clang that ships with fedora:30 and not on the selection used to
build from the clang repo in my machine:

[acme@quaco perf]$ rm -rf /tmp/build/perf ; mkdir -p /tmp/build/perf
[acme@quaco perf]$ make -C tools/perf CC=clang EXTRA_CFLAGS="-fsanitize=address -DADDRESS_SANITIZER=1" O=/tmp/build/perf
make: Entering directory '/home/acme/git/perf/tools/perf'
  BUILD:   Doing 'make -j8' parallel build
  HOSTCC   /tmp/build/perf/fixdep.o
  HOSTLD   /tmp/build/perf/fixdep-in.o
  LINK     /tmp/build/perf/fixdep

Auto-detecting system features:
...                         dwarf: [ OFF ]
...            dwarf_getlocations: [ OFF ]
...                         glibc: [ OFF ]
...                          gtk2: [ OFF ]
...                      libaudit: [ OFF ]
...                        libbfd: [ OFF ]
...                        libelf: [ OFF ]
...                       libnuma: [ OFF ]
...        numa_num_possible_cpus: [ OFF ]
...                       libperl: [ OFF ]
...                     libpython: [ OFF ]
...                     libcrypto: [ OFF ]
...                     libunwind: [ OFF ]
...            libdw-dwarf-unwind: [ OFF ]
...                          zlib: [ OFF ]
...                          lzma: [ OFF ]
...                     get_cpuid: [ OFF ]
...                           bpf: [ OFF ]
...                        libaio: [ OFF ]
...                       libzstd: [ OFF ]
...        disassembler-four-args: [ OFF ]

Makefile.config:368: *** No gnu/libc-version.h found, please install glibc-dev[el].  Stop.
make[1]: *** [Makefile.perf:219: sub-make] Error 2
make: *** [Makefile:70: all] Error 2
make: Leaving directory '/home/acme/git/perf/tools/perf'
[acme@quaco perf]$ cat /tmp/build/perf/feature/test-glibc.make.output
/usr/bin/ld: cannot find /opt/llvm/lib/clang/9.0.0/lib/linux/libclang_rt.asan-x86_64.a: No such file or directory
clang-8: error: linker command failed with exit code 1 (use -v to see invocation)
[acme@quaco perf]$

So I'll check and select that to get to the set of instructions needed
to use this.

- Arnaldo
 
> Signed-off-by: Numfor Mbiziwo-Tiapo <nums@google.com>
> ---
>  tools/perf/tests/perf-hooks.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/tests/perf-hooks.c b/tools/perf/tests/perf-hooks.c
> index a693bcf017ea..3f5f4b28cf01 100644
> --- a/tools/perf/tests/perf-hooks.c
> +++ b/tools/perf/tests/perf-hooks.c
> @@ -7,7 +7,14 @@
>  #include "util.h"
>  #include "perf-hooks.h"
>  
> -static void sigsegv_handler(int sig __maybe_unused)
> +#if defined(ADDRESS_SANITIZER) || defined(MEMORY_SANITIZER) || \
> +defined(THREAD_SANITIZER) || defined(SAFESTACK_SANITIZER)
> +#define USE_SIGNAL 1
> +#else
> +#define USE_SIGNAL 0
> +#endif
> +
> +static void signal_handler(int sig __maybe_unused)
>  {
>  	pr_debug("SIGSEGV is observed as expected, try to recover.\n");
>  	perf_hooks__recover();
> @@ -25,6 +32,9 @@ static void the_hook(void *_hook_flags)
>  	*hook_flags = 1234;
>  
>  	/* Generate a segfault, test perf_hooks__recover */
> +#if USE_SIGNAL
> +	raise(SIGILL);
> +#endif
>  	*p = 0;
>  }
>  
> @@ -32,7 +42,7 @@ int test__perf_hooks(struct test *test __maybe_unused, int subtest __maybe_unuse
>  {
>  	int hook_flags = 0;
>  
> -	signal(SIGSEGV, sigsegv_handler);
> +	signal(USE_SIGNAL ? SIGILL : SIGSEGV, signal_handler);
>  	perf_hooks__set_hook("test", the_hook, &hook_flags);
>  	perf_hooks__invoke_test();
>  
> -- 
> 2.22.0.410.gd8fdbe21b5-goog

-- 

- Arnaldo