diff options
author | Yabin Cui <[email protected]> | 2018-08-23 15:59:35 -0700 |
---|---|---|
committer | Ingo Molnar <[email protected]> | 2018-09-10 14:01:46 +0200 |
commit | 02e184476eff848273826c1d6617bb37e5bcc7ad (patch) | |
tree | 08cf74e197794bbc4226a42d420c060df87c6b3e | |
parent | 09121255c784fd36ad6237a4e239c634b0209de0 (diff) |
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 <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Cc: <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Fixes: 88b0193d9418 ("perf/callchain: Force USER_DS when invoking perf_callchain_user()")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
-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); |