Commit-ID: 1fd466efc88c48f50e5ee29f4dbb4e210a889172 Gitweb: http://git.kernel.org/tip/1fd466efc88c48f50e5ee29f4dbb4e210a889172 Author: Steven Rostedt <srostedt@xxxxxxxxxx> AuthorDate: Thu, 8 Dec 2011 12:32:27 -0500 Committer: Steven Rostedt <rostedt@xxxxxxxxxxx> CommitDate: Wed, 21 Dec 2011 15:38:53 -0500 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@xxxxxxxxxxxxxxxxxxxx> Cc: Andi Kleen <andi@xxxxxxxxxxxxxx> Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx> --- arch/x86/kernel/entry_64.S | 9 ++++++++- 1 files changed, 8 insertions(+), 1 deletions(-) diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 3819ea9..d1d5434 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -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 */ -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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