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Commit 1fd466ef authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt
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x86: Document the NMI handler about not using paranoid_exit 



Linus cleaned up the NMI handler but it still needs some comments to
explain why it uses save_paranoid but not paranoid_exit. Just to keep
others from adding that in the future, document why it's not used.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 549c89b9

arch/x86/kernel/entry_64.S

+8 −1
Original line number Diff line number Diff line
@@ -1480,9 +1480,16 @@ END(error_exit) 
ENTRY(nmi)

	INTR_FRAME

	PARAVIRT_ADJUST_EXCEPTION_FRAME

	pushq_cfi $-1

	pushq_cfi $-1		/* ORIG_RAX: no syscall to restart */

	subq $ORIG_RAX-R15, %rsp

	CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15

	/*

	 * Use save_paranoid to handle SWAPGS, but no need to use paranoid_exit

	 * as we should not be calling schedule in NMI context.

	 * Even with normal interrupts enabled. An NMI should not be

	 * setting NEED_RESCHED or anything that normal interrupts and

	 * exceptions might do.

	 */

	call save_paranoid

	DEFAULT_FRAME 0

	/* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */