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| author | Yabin Cui <yabinc@google.com> | 2018-08-23 15:59:35 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-09-10 14:01:46 +0200 |
| commit | 02e184476eff848273826c1d6617bb37e5bcc7ad (patch) | |
| tree | 08cf74e197794bbc4226a42d420c060df87c6b3e /kernel | |
| parent | 09121255c784fd36ad6237a4e239c634b0209de0 (diff) | |
| download | lwn-02e184476eff848273826c1d6617bb37e5bcc7ad.tar.gz lwn-02e184476eff848273826c1d6617bb37e5bcc7ad.zip | |
perf/core: Force USER_DS when recording user stack data
Perf can record user stack data in response to a synchronous request, such
as a tracepoint firing. If this happens under set_fs(KERNEL_DS), then we
end up reading user stack data using __copy_from_user_inatomic() under
set_fs(KERNEL_DS). I think this conflicts with the intention of using
set_fs(KERNEL_DS). And it is explicitly forbidden by hardware on ARM64
when both CONFIG_ARM64_UAO and CONFIG_ARM64_PAN are used.
So fix this by forcing USER_DS when recording user stack data.
Signed-off-by: Yabin Cui <yabinc@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 88b0193d9418 ("perf/callchain: Force USER_DS when invoking perf_callchain_user()")
Link: http://lkml.kernel.org/r/20180823225935.27035-1-yabinc@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/events/core.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index abaed4f8bb7f..c80549bf82c6 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5943,6 +5943,7 @@ perf_output_sample_ustack(struct perf_output_handle *handle, u64 dump_size, unsigned long sp; unsigned int rem; u64 dyn_size; + mm_segment_t fs; /* * We dump: @@ -5960,7 +5961,10 @@ perf_output_sample_ustack(struct perf_output_handle *handle, u64 dump_size, /* Data. */ sp = perf_user_stack_pointer(regs); + fs = get_fs(); + set_fs(USER_DS); rem = __output_copy_user(handle, (void *) sp, dump_size); + set_fs(fs); dyn_size = dump_size - rem; perf_output_skip(handle, rem); |