summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorTakao Indoh <indou.takao@jp.fujitsu.com>2015-11-04 14:22:33 +0900
committerIngo Molnar <mingo@kernel.org>2015-11-23 09:58:26 +0100
commitda06a43d3f3f3df87416f654fe15d29fecb5e321 (patch)
tree7ccc8fb9e2f34b8e4bf3d6cd812f21b6d65df8a5
parent24cc12b17679f8e9046746f92fd377f589efc163 (diff)
perf, x86: Stop Intel PT before kdump starts
This patch stops Intel PT logging and saves its registers in memory before kdump is started. This feature is needed to prevent Intel PT from overwriting its log buffer after panic, and saved registers are needed to find the last position where Intel PT wrote data. After the crash dump is captured by kdump, users can retrieve the log buffer from the vmcore and use it to investigate bad kernel behavior. 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/1446614553-6072-3-git-send-email-indou.takao@jp.fujitsu.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--arch/x86/kernel/crash.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index 2c1910f6717e..58f34319b29a 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -35,6 +35,7 @@
#include <asm/cpu.h>
#include <asm/reboot.h>
#include <asm/virtext.h>
+#include <asm/intel_pt.h>
/* Alignment required for elf header segment */
#define ELF_CORE_HEADER_ALIGN 4096
@@ -125,6 +126,11 @@ static void kdump_nmi_callback(int cpu, struct pt_regs *regs)
cpu_emergency_vmxoff();
cpu_emergency_svm_disable();
+ /*
+ * Disable Intel PT to stop its logging
+ */
+ cpu_emergency_stop_pt();
+
disable_local_APIC();
}
@@ -169,6 +175,11 @@ void native_machine_crash_shutdown(struct pt_regs *regs)
cpu_emergency_vmxoff();
cpu_emergency_svm_disable();
+ /*
+ * Disable Intel PT to stop its logging
+ */
+ cpu_emergency_stop_pt();
+
#ifdef CONFIG_X86_IO_APIC
/* Prevent crash_kexec() from deadlocking on ioapic_lock. */
ioapic_zap_locks();