From: Yabin Cui Date: Thu, 23 Aug 2018 22:59:35 +0000 (-0700) Subject: perf/core: Force USER_DS when recording user stack data X-Git-Tag: v4.9.129~37 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=a64fbecec98a4aa9d53eac307e057c630e702ad8;p=platform%2Fkernel%2Flinux-amlogic.git perf/core: Force USER_DS when recording user stack data commit 02e184476eff848273826c1d6617bb37e5bcc7ad upstream. 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 Acked-by: Peter Zijlstra (Intel) Cc: Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Thomas Gleixner 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 Signed-off-by: Greg Kroah-Hartman --- diff --git a/kernel/events/core.c b/kernel/events/core.c index 6e6ec229c780..95bd00d9f2c3 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5563,6 +5563,7 @@ 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: @@ -5580,7 +5581,10 @@ 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);