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Commit 36f1a77b authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar
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x86/nmi/64: Make the "NMI executing" variable more consistent 



Currently, "NMI executing" is one the first time an outermost
NMI hits repeat_nmi and zero thereafter.  Change it to be zero
each time for consistency.

This is intended to help NMI handling fail harder if it's buggy.

Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
Reviewed-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 23a781e9

arch/x86/entry/entry_64.S

+5 −6
Original line number Diff line number Diff line
@@ -1441,8 +1441,8 @@ first_nmi: 
	/* Restore rdx. */

	movq	(%rsp), %rdx



	/* Set "NMI executing" on the stack. */

	pushq	$1

	/* Make room for "NMI executing". */

	pushq	$0



	/* Leave room for the "iret" frame */

	subq	$(5*8), %rsp
@@ -1467,11 +1467,10 @@ repeat_nmi: 
	 * RSP is pointing to "outermost RIP".  gsbase is unknown, but, if

	 * we're repeating an NMI, gsbase has the same value that it had on

	 * the first iteration.  paranoid_entry will load the kernel

	 * gsbase if needed before we call do_nmi.

	 *

	 * Set "NMI executing" in case we came back here via IRET.

	 * gsbase if needed before we call do_nmi.  "NMI executing"

	 * is zero.

	 */

	movq	$1, 10*8(%rsp)

	movq	$1, 10*8(%rsp)		/* Set "NMI executing". */



	/*

	 * Copy the "outermost" frame to the "iret" frame.  NMIs that nest