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x86/traps: Disentangle the 32-bit and 64-bit doublefault code

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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>
This commit is contained in:
Andy Lutomirski 2019-11-20 22:12:38 -08:00 committed by Ingo Molnar
parent b09511c253
commit 93efbde2c3
4 changed files with 4 additions and 22 deletions
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2
arch/x86/Kconfig.debug
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@ -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

1
arch/x86/include/asm/processor.h
View File

@ -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 {

11
arch/x86/kernel/doublefault.c
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@ -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

12
arch/x86/kernel/traps.c
View File

@ -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