[PATCH v5 2/7] perf/x86/intel: Record branch type

Jin Yao
2017-04-19T07:50:50Z

Perf already has support for disassembling the branch instruction
and using the branch type for filtering. The patch just records
the branch type in perf_branch_entry.

Before recording, the patch converts the x86 branch type to
common branch type.

Change log
----------

v5: Just fix the merge error. No other update.

v4: Comparing to previous version, the major changes are:

1. Uses a lookup table to convert x86 branch type to common branch
type.

2. Move the JCC forward/JCC backward and cross page computing to
user space.

3. Initialize branch type to 0 in intel_pmu_lbr_read_32 and
intel_pmu_lbr_read_64

Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
---
arch/x86/events/intel/lbr.c | 53 ++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 52 insertions(+), 1 deletion(-)

diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c
index f924629..f10a7ed 100644
--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -109,6 +109,9 @@ enum {
X86_BR_ZERO_CALL = 1 << 15,/* zero length call */
X86_BR_CALL_STACK = 1 << 16,/* call stack */
X86_BR_IND_JMP = 1 << 17,/* indirect jump */
+
+ X86_BR_TYPE_SAVE = 1 << 18,/* indicate to save branch type */
+
};

#define X86_BR_PLM (X86_BR_USER | X86_BR_KERNEL)
@@ -510,6 +513,7 @@ static void intel_pmu_lbr_read_32(struct cpu_hw_events *cpuc)
cpuc->lbr_entries[i].in_tx = 0;
cpuc->lbr_entries[i].abort = 0;
cpuc->lbr_entries[i].cycles = 0;
+ cpuc->lbr_entries[i].type = 0;
cpuc->lbr_entries[i].reserved = 0;
}
cpuc->lbr_stack.nr = i;
@@ -596,6 +600,7 @@ static void intel_pmu_lbr_read_64(struct cpu_hw_events *cpuc)
cpuc->lbr_entries[out].in_tx = in_tx;
cpuc->lbr_entries[out].abort = abort;
cpuc->lbr_entries[out].cycles = cycles;
+ cpuc->lbr_entries[out].type = 0;
cpuc->lbr_entries[out].reserved = 0;
out++;
}
@@ -673,6 +678,10 @@ static int intel_pmu_setup_sw_lbr_filter(struct perf_event *event)

if (br_type & PERF_SAMPLE_BRANCH_CALL)
mask |= X86_BR_CALL | X86_BR_ZERO_CALL;
+
+ if (br_type & PERF_SAMPLE_BRANCH_TYPE_SAVE)
+ mask |= X86_BR_TYPE_SAVE;
+
/*
* stash actual user request into reg, it may
* be used by fixup code for some CPU
@@ -926,6 +935,44 @@ static int branch_type(unsigned long from, unsigned long to, int abort)
return ret;
}

+#define X86_BR_TYPE_MAP_MAX 16
+
+static int
+common_branch_type(int type)
+{
+ int i, mask;
+ const int branch_map[X86_BR_TYPE_MAP_MAX] = {
+ PERF_BR_CALL, /* X86_BR_CALL */
+ PERF_BR_RET, /* X86_BR_RET */
+ PERF_BR_SYSCALL, /* X86_BR_SYSCALL */
+ PERF_BR_SYSRET, /* X86_BR_SYSRET */
+ PERF_BR_INT, /* X86_BR_INT */
+ PERF_BR_IRET, /* X86_BR_IRET */
+ PERF_BR_JCC, /* X86_BR_JCC */
+ PERF_BR_JMP, /* X86_BR_JMP */
+ PERF_BR_IRQ, /* X86_BR_IRQ */
+ PERF_BR_IND_CALL, /* X86_BR_IND_CALL */
+ PERF_BR_NONE, /* X86_BR_ABORT */
+ PERF_BR_NONE, /* X86_BR_IN_TX */
+ PERF_BR_NONE, /* X86_BR_NO_TX */
+ PERF_BR_CALL, /* X86_BR_ZERO_CALL */
+ PERF_BR_NONE, /* X86_BR_CALL_STACK */
+ PERF_BR_IND_JMP, /* X86_BR_IND_JMP */
+ };
+
+ type >>= 2; /* skip X86_BR_USER and X86_BR_KERNEL */
+ mask = ~(~0 << 1);
+
+ for (i = 0; i < X86_BR_TYPE_MAP_MAX; i++) {
+ if (type & mask)
+ return branch_map[i];
+
+ type >>= 1;
+ }
+
+ return PERF_BR_NONE;
+}
+
/*
* implement actual branch filter based on user demand.
* Hardware may not exactly satisfy that request, thus
@@ -942,7 +989,8 @@ intel_pmu_lbr_filter(struct cpu_hw_events *cpuc)
bool compress = false;

/* if sampling all branches, then nothing to filter */
- if ((br_sel & X86_BR_ALL) == X86_BR_ALL)
+ if (((br_sel & X86_BR_ALL) == X86_BR_ALL) &&
+ ((br_sel & X86_BR_TYPE_SAVE) != X86_BR_TYPE_SAVE))
return;

for (i = 0; i < cpuc->lbr_stack.nr; i++) {
@@ -963,6 +1011,9 @@ intel_pmu_lbr_filter(struct cpu_hw_events *cpuc)
cpuc->lbr_entries[i].from = 0;
compress = true;
}
+
+ if ((br_sel & X86_BR_TYPE_SAVE) == X86_BR_TYPE_SAVE)
+ cpuc->lbr_entries[i].type = common_branch_type(type);
}

if (!compress)
--
2.7.4