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authorAndy Lutomirski <luto@kernel.org>2019-11-20 22:12:38 -0800
committerIngo Molnar <mingo@kernel.org>2019-11-26 21:53:34 +0100
commit93efbde2c331004d8053f04b4bf0ca3e630b474a (patch)
treeda94642f314fb062e92a555eca60d8d072e98ae7
parentb09511c253e5c739a60952b97c071a93e92b2e88 (diff)
downloadlinux-93efbde2c331004d8053f04b4bf0ca3e630b474a.tar.gz
x86/traps: Disentangle the 32-bit and 64-bit doublefault code
The 64-bit doublefault handler is much nicer than the 32-bit one.
As a first step toward unifying them, make the 64-bit handler
self-contained.  This should have no effect no functional effect
except in the odd case of x86_64 with CONFIG_DOUBLEFAULT=n in which
case it will change the logging a bit.

This also gets rid of CONFIG_DOUBLEFAULT configurability on 64-bit
kernels.  It didn't do anything useful -- CONFIG_DOUBLEFAULT=n
didn't actually disable doublefault handling on x86_64.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--arch/x86/Kconfig.debug2
-rw-r--r--arch/x86/include/asm/processor.h1
-rw-r--r--arch/x86/kernel/doublefault.c11
-rw-r--r--arch/x86/kernel/traps.c12
4 files changed, 4 insertions, 22 deletions
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 409c00f74e60..c4eab8ed33a3 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -117,7 +117,7 @@ config DEBUG_WX
 
 config DOUBLEFAULT
 	default y
-	bool "Enable doublefault exception handler" if EXPERT
+	bool "Enable doublefault exception handler" if EXPERT && 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 e51afbb0cbfb..f6c630097d9f 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -997,7 +997,6 @@ bool xen_set_default_idle(void);
 #endif
 
 void stop_this_cpu(void *dummy);
-void df_debug(struct pt_regs *regs, long error_code);
 void microcode_check(void);
 
 enum l1tf_mitigations {
diff --git a/arch/x86/kernel/doublefault.c b/arch/x86/kernel/doublefault.c
index 0d6c657593f8..0b3c616b61a3 100644
--- a/arch/x86/kernel/doublefault.c
+++ b/arch/x86/kernel/doublefault.c
@@ -72,15 +72,4 @@ struct x86_hw_tss 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 c90312146da0..76381b04dc93 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -411,15 +411,9 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsign
 		handle_stack_overflow("kernel stack overflow (double-fault)", regs, cr2);
 #endif
 
-#ifdef CONFIG_DOUBLEFAULT
-	df_debug(regs, error_code);
-#endif
-	/*
-	 * This is always a kernel trap and never fixable (and thus must
-	 * never return).
-	 */
-	for (;;)
-		die(str, regs, error_code);
+	pr_emerg("PANIC: double fault, error_code: 0x%lx\n", error_code);
+	show_regs(regs);
+	panic("Machine halted.");
 }
 #endif