From: Borislav Petkov <b...@suse.de>
It is sometimes very helpful to be able to pinpoint the location which
causes a double fault before it turns into a triple fault and the
machine reboots. We have this for 32-bit already so extend it to 64-bit.
On 64-bit we get the register snapshot at #DF time and not from the
first exception which actually causes the #DF. It should be close
enough, though.
Signed-off-by: Borislav Petkov <b...@suse.de>
---
arch/x86/Kconfig.debug | 1 -
arch/x86/include/asm/processor.h | 2 +-
arch/x86/kernel/Makefile | 2 +-
arch/x86/kernel/{doublefault_32.c => doublefault.c} | 15 +++++++++++++++
arch/x86/kernel/traps.c | 3 +++
5 files changed, 20 insertions(+), 3 deletions(-)
rename arch/x86/kernel/{doublefault_32.c => doublefault.c} (84%)
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index c198b7e13e7b..b6a770132b67 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -122,7 +122,6 @@ config DEBUG_NX_TEST
config DOUBLEFAULT
default y
bool "Enable doublefault exception handler" if EXPERT
- depends on X86_32
---help---
This option allows trapping of rare doublefault exceptions that
would otherwise cause a system to silently reboot. Disabling this
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 22224b3b43bb..5b87d52eed0b 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -981,5 +981,5 @@ bool xen_set_default_idle(void);
#endif
void stop_this_cpu(void *dummy);
-
+void df_debug(struct pt_regs *regs, long error_code);
#endif /* _ASM_X86_PROCESSOR_H */
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 7bd3bd310106..acb3b031f711 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -67,7 +67,7 @@ obj-$(CONFIG_KEXEC) += relocate_kernel_$(BITS).o
crash.o
obj-$(CONFIG_CRASH_DUMP) += crash_dump_$(BITS).o
obj-y += kprobes/
obj-$(CONFIG_MODULES) += module.o
-obj-$(CONFIG_DOUBLEFAULT) += doublefault_32.o
+obj-$(CONFIG_DOUBLEFAULT) += doublefault.o
obj-$(CONFIG_KGDB) += kgdb.o
obj-$(CONFIG_VM86) += vm86_32.o
obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
diff --git a/arch/x86/kernel/doublefault_32.c b/arch/x86/kernel/doublefault.c
similarity index 84%
rename from arch/x86/kernel/doublefault_32.c
rename to arch/x86/kernel/doublefault.c
index 155a13f33ed8..5d3fe8d36e4a 100644
--- a/arch/x86/kernel/doublefault_32.c
+++ b/arch/x86/kernel/doublefault.c
@@ -9,6 +9,8 @@
#include <asm/processor.h>
#include <asm/desc.h>
+#ifdef CONFIG_X86_32
+
#define DOUBLEFAULT_STACKSIZE (1024)
static unsigned long doublefault_stack[DOUBLEFAULT_STACKSIZE];
#define STACK_START (unsigned long)(doublefault_stack+DOUBLEFAULT_STACKSIZE)
@@ -67,3 +69,16 @@ struct tss_struct doublefault_tss __cacheline_aligned = {
.__cr3 = __pa_nodebug(swapper_pg_dir),
}
};
+
+/* dummy for do_double_fault() call */
+void df_debug(struct pt_regs *regs, long error_code) {}
+
+#else /* !CONFIG_X86_32 */
+
+void df_debug(struct pt_regs *regs, long error_code)
+{
+ pr_emerg("PANIC: double fault, error_code: 0x%lx\n", error_code);
+ show_regs(regs);
+ panic("Machine halted.");
+}
+#endif
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 772e2a846dec..167d481c5fd3 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -254,6 +254,9 @@ dotraplinkage void do_double_fault(struct pt_regs *regs,
long error_code)
tsk->thread.error_code = error_code;
tsk->thread.trap_nr = X86_TRAP_DF;
+#ifdef CONFIG_DOUBLEFAULT
+ df_debug(regs, error_code);
+#endif
/*
* This is always a kernel trap and never fixable (and thus must
* never return).
--
1.8.3.rc0
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