The following commit has been merged into the perf/core branch of tip:
Commit-ID: 117ceeb1f4f87331e45a77e71f18303d15ec882e
Gitweb: https://git.kernel.org/tip/117ceeb1f4f87331e45a77e71f18303d15ec882e
Author: Stephane Eranian <eranian@xxxxxxxxxx>
AuthorDate: Wed, 28 Sep 2022 11:40:42 -07:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Thu, 29 Sep 2022 12:20:56 +02:00
perf/x86/utils: Fix uninitialized var in get_branch_type()
offset is passed as a pointer and on certain call path is not set by the
function. If the caller does not re-initialize offset between calls, value
could be inherited between calls. Prevent this by initializing offset on each
call.
This impacts the code in amd_pmu_lbr_filter() which does:
for(i=0; ...) {
ret = get_branch_type_fused(..., &offset);
if (offset)
lbr_entries[i].from += offset;
}
Fixes: df3e9612f758 ("perf/x86: Make branch classifier fusion-aware")
Signed-off-by: Stephane Eranian <eranian@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Sandipan Das <sandipan.das@xxxxxxx>
Link: https://lore.kernel.org/r/20220928184043.408364-2-eranian@xxxxxxxxxx
---
arch/x86/events/utils.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/x86/events/utils.c b/arch/x86/events/utils.c
index 5f5617a..76b1f8b 100644
--- a/arch/x86/events/utils.c
+++ b/arch/x86/events/utils.c
@@ -94,6 +94,10 @@ static int get_branch_type(unsigned long from, unsigned long to, int abort,
u8 buf[MAX_INSN_SIZE];
int is64 = 0;
+ /* make sure we initialize offset */
+ if (offset)
+ *offset = 0;
+
to_plm = kernel_ip(to) ? X86_BR_KERNEL : X86_BR_USER;
from_plm = kernel_ip(from) ? X86_BR_KERNEL : X86_BR_USER;
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