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 <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Alexander Shishkin<[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: H.Peter Anvin <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vince Weaver <[email protected]>
Cc: Vivek Goyal <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/arch/x86/include/asm/intel_pt.h b/arch/x86/include/asm/intel_pt.h
new file mode 100644 (file)
index 0000000..e1a4117
--- /dev/null
+++ b/arch/x86/include/asm/intel_pt.h
@@ -0,0 +1,10 @@
+#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 */

diff --git a/arch/x86/kernel/cpu/perf_event_intel_pt.c b/arch/x86/kernel/cpu/perf_event_intel_pt.c
index 868e1194337f6cf93cd1a8048480a60aa7acf3e3..c0bbd1033b7cb380afea0379a015b5a12e179824 100644 (file)
--- a/arch/x86/kernel/cpu/perf_event_intel_pt.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_pt.c
@@ -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;