perf/x86/amd/lbr: Adjust LBR regardless of filtering
authorStephane Eranian <eranian@google.com>
Wed, 28 Sep 2022 18:40:43 +0000 (11:40 -0700)
committerPeter Zijlstra <peterz@infradead.org>
Thu, 29 Sep 2022 10:20:57 +0000 (12:20 +0200)
commit3f9a1b3591003b122a6ea2d69f89a0fd96ec58b9
treebee8e3918c57f7e42f8bc3fd9c94ffed86f1d98c
parent117ceeb1f4f87331e45a77e71f18303d15ec882e
perf/x86/amd/lbr: Adjust LBR regardless of filtering

In case of fused compare and taken branch instructions, the AMD LBR points to
the compare instruction instead of the branch. Users of LBR usually expects
the from address to point to a branch instruction. The kernel has code to
adjust the from address via get_branch_type_fused(). However this correction
is only applied when a branch filter is applied. That means that if no
filter is present, the quality of the data is lower.

Fix the problem by applying the adjustment regardless of the filter setting,
bringing the AMD LBR to the same level as other LBR implementations.

Fixes: 245268c19f70 ("perf/x86/amd/lbr: Use fusion-aware branch classifier")
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Sandipan Das <sandipan.das@amd.com>
Link: https://lore.kernel.org/r/20220928184043.408364-3-eranian@google.com
arch/x86/events/amd/lbr.c