linux-kernel - [PATCH 4.14 069/159] perf/x86: Enable free running PEBS for REGS

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Date:   Fri, 22 Dec 2017 09:45:54 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>
Subject: [PATCH 4.14 069/159] perf/x86: Enable free running PEBS for REGS_USER/INTR

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andi Kleen <ak@...ux.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@...ux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/20170831214630.21892-1-andi@firstfloor.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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.
  */