Commit-ID: da06a43d3f3f3df87416f654fe15d29fecb5e321 Gitweb: http://git.kernel.org/tip/da06a43d3f3f3df87416f654fe15d29fecb5e321 Author: Takao Indoh <indou.takao@xxxxxxxxxxxxxx> AuthorDate: Wed, 4 Nov 2015 14:22:33 +0900 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Mon, 23 Nov 2015 09:58:26 +0100 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@xxxxxxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Cc: Alexander Shishkin<alexander.shishkin@xxxxxxxxxxxxxxx> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Cc: H.Peter Anvin <hpa@xxxxxxxxx> Cc: Jiri Olsa <jolsa@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Mike Galbraith <efault@xxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Stephane Eranian <eranian@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Vince Weaver <vincent.weaver@xxxxxxxxx> Cc: Vivek Goyal <vgoyal@xxxxxxxxxx> Link: http://lkml.kernel.org/r/1446614553-6072-3-git-send-email-indou.takao@xxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- arch/x86/kernel/crash.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c index 2c1910f..58f3431 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(); -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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