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    Subject[PATCH v2 4/4] x86: Stop Intel PT and save its registers when panic occurs
    Date
    When panic occurs, Intel PT logging is stopped to prevent it from
    overwrite its log buffer. The registers of Intel PT are saved in the
    memory on panic, they are needed for debugger to find the last position
    where Intel PT wrote data.

    Signed-off-by: Takao Indoh <indou.takao@jp.fujitsu.com>
    ---
    arch/x86/kernel/crash.c | 9 +++++++++
    1 files changed, 9 insertions(+), 0 deletions(-)

    diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
    index e068d66..78deceb 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_log.h>

    /* Alignment required for elf header segment */
    #define ELF_CORE_HEADER_ALIGN 4096
    @@ -127,6 +128,10 @@ static void kdump_nmi_callback(int cpu, struct pt_regs *regs)
    cpu_emergency_vmxoff();
    cpu_emergency_svm_disable();

    +#ifdef CONFIG_X86_INTEL_PT_LOG
    + save_intel_pt_registers();
    +#endif
    +
    disable_local_APIC();
    }

    @@ -172,6 +177,10 @@ void native_machine_crash_shutdown(struct pt_regs *regs)
    cpu_emergency_vmxoff();
    cpu_emergency_svm_disable();

    +#ifdef CONFIG_X86_INTEL_PT_LOG
    + save_intel_pt_registers();
    +#endif
    +
    #ifdef CONFIG_X86_IO_APIC
    /* Prevent crash_kexec() from deadlocking on ioapic_lock. */
    ioapic_zap_locks();
    --
    1.7.1



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