Commit 24cc12b1 authored Nov 04, 2015 by Takao Indoh Committed by Ingo Molnar Nov 23, 2015

perf/x86/intel/pt: Add interface to stop Intel PT logging



This patch add a function for external components to stop Intel PT.
Basically this function is used when kernel panic occurs. When it is
called, the intel_pt driver disables Intel PT and saves its registers
using pt_event_stop(), which is also used by pmu.stop handler.

This function stops Intel PT on the CPU where it is working, therefore
users of it need to call it for each CPU to stop all logging.

Signed-off-by: Takao Indoh <indou.takao@jp.fujitsu.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin<alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: H.Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Vivek Goyal <vgoyal@redhat.com>
Link: http://lkml.kernel.org/r/1446614553-6072-2-git-send-email-indou.takao@jp.fujitsu.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent b16a5b52

arch/x86/include/asm/intel_pt.h

0 → 100644

+10 −0

Original line number	Diff line number	Diff line
		#ifndef _ASM_X86_INTEL_PT_H
		#define _ASM_X86_INTEL_PT_H

		#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_INTEL)
		void cpu_emergency_stop_pt(void);
		#else
		static inline void cpu_emergency_stop_pt(void) {}
		#endif

		#endif /* _ASM_X86_INTEL_PT_H */

arch/x86/kernel/cpu/perf_event_intel_pt.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -27,6 +27,7 @@
		#include <asm/perf_event.h>
		#include <asm/insn.h>
		#include <asm/io.h>
		#include <asm/intel_pt.h>

		#include "perf_event.h"
		#include "intel_pt.h"
		@@ -1122,6 +1123,14 @@ static int pt_event_init(struct perf_event *event)
		return 0;
		}

		void cpu_emergency_stop_pt(void)
		{
		struct pt *pt = this_cpu_ptr(&pt_ctx);

		if (pt->handle.event)
		pt_event_stop(pt->handle.event, PERF_EF_UPDATE);
		}

		static __init int pt_init(void)
		{
		int ret, cpu, prior_warn = 0;

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