perf/x86: Add support for PERF_SAMPLE_BRANCH_CALL

This change “perf/x86: Add support for PERF_SAMPLE_BRANCH_CALL” in Linux kernel is authored by Stephane Eranian <eranian [at] google.com> on Tue Oct 13 09:09:09 2015 +0200.

perf/x86: Add support for PERF_SAMPLE_BRANCH_CALL

This patch enables the suport for the PERF_SAMPLE_BRANCH_CALL
for Intel x86 processors. When the processor support LBR filtering
this the selection is done in hardware. Otherwise, the filter is
applied by software. Note that we chose to include zero length calls
because they also represent calls.

Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: khandual@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/1444720151-10275-3-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

This Linux change may have been applied to various maintained Linux releases and you can find Linux releases including commit d892819.

There are 4 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 arch/x86/kernel/cpu/perf_event_intel_lbr.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
index ad0b8b0..bfd0b71 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
@@ -555,6 +555,8 @@ static int intel_pmu_setup_sw_lbr_filter(struct perf_event *event)
 	if (br_type & PERF_SAMPLE_BRANCH_IND_JUMP)
 		mask |= X86_BR_IND_JMP;
 
+	if (br_type & PERF_SAMPLE_BRANCH_CALL)
+		mask |= X86_BR_CALL | X86_BR_ZERO_CALL;
 	/*
 	 * stash actual user request into reg, it may
 	 * be used by fixup code for some CPU
@@ -890,6 +892,7 @@ static int branch_type(unsigned long from, unsigned long to, int abort)
 	[PERF_SAMPLE_BRANCH_IND_CALL_SHIFT]	= LBR_IND_CALL,
 	[PERF_SAMPLE_BRANCH_COND_SHIFT]		= LBR_JCC,
 	[PERF_SAMPLE_BRANCH_IND_JUMP_SHIFT]	= LBR_IND_JMP,
+	[PERF_SAMPLE_BRANCH_CALL_SHIFT]		= LBR_REL_CALL,
 };
 
 static const int hsw_lbr_sel_map[PERF_SAMPLE_BRANCH_MAX_SHIFT] = {
@@ -905,6 +908,7 @@ static int branch_type(unsigned long from, unsigned long to, int abort)
 	[PERF_SAMPLE_BRANCH_CALL_STACK_SHIFT]	= LBR_REL_CALL | LBR_IND_CALL
 						| LBR_RETURN | LBR_CALL_STACK,
 	[PERF_SAMPLE_BRANCH_IND_JUMP_SHIFT]	= LBR_IND_JMP,
+	[PERF_SAMPLE_BRANCH_CALL_SHIFT]		= LBR_REL_CALL,
 };
 
 /* core */

The commit for this change in Linux stable tree is d892819 (patch).

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