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authorMadhavan Srinivasan <maddy@linux.vnet.ibm.com>2016-08-17 15:06:08 +0530
committerIngo Molnar <mingo@kernel.org>2016-08-18 10:44:20 +0200
commit29dd3288705f26cc27663e79061209dabce2d5b9 (patch)
treeb73441ec4167b7b185a36cf368382ed4fda6e224 /kernel/events/core.c
parent8942c2b7f3ab58b140f31653e1a9ea373212930d (diff)
bitmap.h, perf/core: Fix the mask in perf_output_sample_regs()
When decoding the perf_regs mask in perf_output_sample_regs(), we loop through the mask using find_first_bit and find_next_bit functions. While the exisiting code works fine in most of the case, the logic is broken for big-endian 32-bit kernels. When reading a u64 mask using (u32 *)(&val)[0], find_*_bit() assumes that it gets the lower 32 bits of u64, but instead it gets the upper 32 bits - which is wrong. The fix is to swap the words of the u64 to handle this case. This is _not_ a regular endianness swap. Suggested-by: Yury Norov <ynorov@caviumnetworks.com> Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Yury Norov <ynorov@caviumnetworks.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: linuxppc-dev@lists.ozlabs.org Link: http://lkml.kernel.org/r/1471426568-31051-2-git-send-email-maddy@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events/core.c')
-rw-r--r--kernel/events/core.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index ca4fde5ed268..849919c2f3d7 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5340,9 +5340,10 @@ perf_output_sample_regs(struct perf_output_handle *handle,
struct pt_regs *regs, u64 mask)
{
int bit;
+ DECLARE_BITMAP(_mask, 64);
- for_each_set_bit(bit, (const unsigned long *) &mask,
- sizeof(mask) * BITS_PER_BYTE) {
+ bitmap_from_u64(_mask, mask);
+ for_each_set_bit(bit, _mask, sizeof(mask) * BITS_PER_BYTE) {
u64 val;
val = perf_reg_value(regs, bit);