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perf/x86/intel/lbr: Add support for LBRv5

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Add support for the new LBRv5 format used on Intel Skylake CPUs.

The flags for mispredict, abort, in_tx etc. moved to range of separate
LBR_INFO_* MSRs. Teach the LBR code to read those. The original
LBR registers stay the same, except they have full sign
extension now.

LBR_INFO also reports a cycle count to the last branch.
Report the cycle information using the new "cycles" branch_info
output field.

In addition we have to context switch and clear the new INFO
MSRs to avoid any information leaks.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: eranian@google.com
Link: http://lkml.kernel.org/r/1431285767-27027-6-git-send-email-andi@firstfloor.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andi Kleen 2015-05-10 12:22:43 -07:00 committed by Ingo Molnar
parent 71ef3c6b9d
commit 50eab8f6ec
2 changed files with 21 additions and 1 deletions
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1
arch/x86/kernel/cpu/perf_event.h
View File

@ -625,6 +625,7 @@ struct x86_pmu {
struct x86_perf_task_context {
u64 lbr_from[MAX_LBR_ENTRIES];
u64 lbr_to[MAX_LBR_ENTRIES];
u64 lbr_info[MAX_LBR_ENTRIES];
int lbr_callstack_users;
int lbr_stack_state;
};

21
arch/x86/kernel/cpu/perf_event_intel_lbr.c
View File

@ -13,7 +13,8 @@ enum {
LBR_FORMAT_EIP = 0x02,
LBR_FORMAT_EIP_FLAGS = 0x03,
LBR_FORMAT_EIP_FLAGS2 = 0x04,
LBR_FORMAT_MAX_KNOWN = LBR_FORMAT_EIP_FLAGS2,
LBR_FORMAT_INFO = 0x05,
LBR_FORMAT_MAX_KNOWN = LBR_FORMAT_INFO,
};
static enum {
@ -186,6 +187,8 @@ static void intel_pmu_lbr_reset_64(void)
for (i = 0; i < x86_pmu.lbr_nr; i++) {
wrmsrl(x86_pmu.lbr_from + i, 0);
wrmsrl(x86_pmu.lbr_to + i, 0);
if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_INFO)
wrmsrl(MSR_LBR_INFO_0 + i, 0);
}
}
@ -234,6 +237,8 @@ static void __intel_pmu_lbr_restore(struct x86_perf_task_context *task_ctx)
lbr_idx = (tos - i) & mask;
wrmsrl(x86_pmu.lbr_from + lbr_idx, task_ctx->lbr_from[i]);
wrmsrl(x86_pmu.lbr_to + lbr_idx, task_ctx->lbr_to[i]);
if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_INFO)
wrmsrl(MSR_LBR_INFO_0 + i, task_ctx->lbr_info[i]);
}
task_ctx->lbr_stack_state = LBR_NONE;
}
@ -255,6 +260,8 @@ static void __intel_pmu_lbr_save(struct x86_perf_task_context *task_ctx)
lbr_idx = (tos - i) & mask;
rdmsrl(x86_pmu.lbr_from + lbr_idx, task_ctx->lbr_from[i]);
rdmsrl(x86_pmu.lbr_to + lbr_idx, task_ctx->lbr_to[i]);
if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_INFO)
rdmsrl(MSR_LBR_INFO_0 + i, task_ctx->lbr_info[i]);
}
task_ctx->lbr_stack_state = LBR_VALID;
}
@ -416,11 +423,22 @@ static void intel_pmu_lbr_read_64(struct cpu_hw_events *cpuc)
unsigned long lbr_idx = (tos - i) & mask;
u64 from, to, mis = 0, pred = 0, in_tx = 0, abort = 0;
int skip = 0;
u16 cycles = 0;
int lbr_flags = lbr_desc[lbr_format];
rdmsrl(x86_pmu.lbr_from + lbr_idx, from);
rdmsrl(x86_pmu.lbr_to + lbr_idx, to);
if (lbr_format == LBR_FORMAT_INFO) {
u64 info;
rdmsrl(MSR_LBR_INFO_0 + lbr_idx, info);
mis = !!(info & LBR_INFO_MISPRED);
pred = !mis;
in_tx = !!(info & LBR_INFO_IN_TX);
abort = !!(info & LBR_INFO_ABORT);
cycles = (info & LBR_INFO_CYCLES);
}
if (lbr_flags & LBR_EIP_FLAGS) {
mis = !!(from & LBR_FROM_FLAG_MISPRED);
pred = !mis;
@ -450,6 +468,7 @@ static void intel_pmu_lbr_read_64(struct cpu_hw_events *cpuc)
cpuc->lbr_entries[out].predicted = pred;
cpuc->lbr_entries[out].in_tx = in_tx;
cpuc->lbr_entries[out].abort = abort;
cpuc->lbr_entries[out].cycles = cycles;
cpuc->lbr_entries[out].reserved = 0;
out++;
}