[PATCH 4.14 069/159] perf/x86: Enable free running PEBS for REGS_USER/INTR

Greg Kroah-Hartman
2017-12-22T09:01:53Z

From: Andi Kleen <ak@linux.intel.com>

commit 2fe1bc1f501d55e5925b4035bcd85781adc76c63 upstream.

[ Note, this is a Git cherry-pick of the following commit:

a47ba4d77e12 ("perf/x86: Enable free running PEBS for REGS_USER/INTR")

... for easier x86 PTI code testing and back-porting. ]

Currently free running PEBS is disabled when user or interrupt
registers are requested. Most of the registers are actually
available in the PEBS record and can be supported.

So we just need to check for the supported registers and then
allow it: it is all except for the segment register.

For user registers this only works when the counter is limited
to ring 3 only, so this also needs to be checked.

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>
Link: http://lkml.kernel.org/r/20170831214630.21892-1-andi@firstfloor.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/events/intel/core.c | 4 ++++
arch/x86/events/perf_event.h | 24 +++++++++++++++++++++++-
2 files changed, 27 insertions(+), 1 deletion(-)

--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -2958,6 +2958,10 @@ static unsigned long intel_pmu_free_runn

if (event->attr.use_clockid)
flags &= ~PERF_SAMPLE_TIME;
+ if (!event->attr.exclude_kernel)
+ flags &= ~PERF_SAMPLE_REGS_USER;
+ if (event->attr.sample_regs_user & ~PEBS_REGS)
+ flags &= ~(PERF_SAMPLE_REGS_USER | PERF_SAMPLE_REGS_INTR);
return flags;
}

--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -85,13 +85,15 @@ struct amd_nb {
* Flags PEBS can handle without an PMI.
*
* TID can only be handled by flushing at context switch.
+ * REGS_USER can be handled for events limited to ring 3.
*
*/
#define PEBS_FREERUNNING_FLAGS \
(PERF_SAMPLE_IP | PERF_SAMPLE_TID | PERF_SAMPLE_ADDR | \
PERF_SAMPLE_ID | PERF_SAMPLE_CPU | PERF_SAMPLE_STREAM_ID | \
PERF_SAMPLE_DATA_SRC | PERF_SAMPLE_IDENTIFIER | \
- PERF_SAMPLE_TRANSACTION | PERF_SAMPLE_PHYS_ADDR)
+ PERF_SAMPLE_TRANSACTION | PERF_SAMPLE_PHYS_ADDR | \
+ PERF_SAMPLE_REGS_INTR | PERF_SAMPLE_REGS_USER)

/*
* A debug store configuration.
@@ -110,6 +112,26 @@ struct debug_store {
u64 pebs_event_reset[MAX_PEBS_EVENTS];
};

+#define PEBS_REGS \
+ (PERF_REG_X86_AX | \
+ PERF_REG_X86_BX | \
+ PERF_REG_X86_CX | \
+ PERF_REG_X86_DX | \
+ PERF_REG_X86_DI | \
+ PERF_REG_X86_SI | \
+ PERF_REG_X86_SP | \
+ PERF_REG_X86_BP | \
+ PERF_REG_X86_IP | \
+ PERF_REG_X86_FLAGS | \
+ PERF_REG_X86_R8 | \
+ PERF_REG_X86_R9 | \
+ PERF_REG_X86_R10 | \
+ PERF_REG_X86_R11 | \
+ PERF_REG_X86_R12 | \
+ PERF_REG_X86_R13 | \
+ PERF_REG_X86_R14 | \
+ PERF_REG_X86_R15)
+
/*
* Per register state.
*/