Commit 93efbde2 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar
Browse files

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: default avatarAndy 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: default avatarIngo Molnar <mingo@kernel.org>
parent b09511c2

arch/x86/Kconfig.debug

+1 −1
Original line number Diff line number Diff line
@@ -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

arch/x86/include/asm/processor.h

+0 −1
Original line number Diff line number Diff line
@@ -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 {

arch/x86/kernel/doublefault.c

+0 −11
Original line number Diff line number Diff line
@@ -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

arch/x86/kernel/traps.c

+3 −9
Original line number Diff line number Diff line
@@ -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

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