Messages in this thread Patch in this message | | | Subject | [PATCH][GIT PULL][v3.3] x86: Specify a size for the cmp in the NMI handler | From | Steven Rostedt <> | Date | Mon, 20 Feb 2012 18:42:47 -0500 |
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Ingo,
Please pull the latest tip/x86/urgent tree, which can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git tip/x86/urgent
Head SHA1: 869d49dc575a9cf7041e535ea4911a511bbee764
Steven Rostedt (1): x86: Specify a size for the cmp in the NMI handler
---- arch/x86/kernel/entry_64.S | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) --------------------------- commit 869d49dc575a9cf7041e535ea4911a511bbee764 Author: Steven Rostedt <srostedt@redhat.com> Date: Mon Feb 20 15:29:34 2012 -0500
x86: Specify a size for the cmp in the NMI handler Linus noticed that the cmp used to check if the code segment is __KERNEL_CS or not did not specify a size. Perhaps it does not matter as H. Peter Anvin noted that user space can not set the bottom two bits of the %cs register. But it's best not to let the assembly choose and change things between different versions of gas, but instead just pick the size. The full 8 bytes is used to compare the saved code segment against __KERNEL_CS. Perhaps this might mess up Xen, but we can fix that when the time comes. Also I noticed that there was another non-specified cmp that checks the special stack variable if it is 1 or 0. This too probably doesn't matter what cmp is used, but this patch uses cmpl just to make it non ambiguous. Link: http://lkml.kernel.org/r/CA+55aFxfAn9MWRgS3O5k2tqN5ys1XrhSFVO5_9ZAoZKDVgNfGA@mail.gmail.com Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index debd851..666f2cb 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -1535,14 +1535,14 @@ ENTRY(nmi) * If %cs was not the kernel segment, then the NMI triggered in user * space, which means it is definitely not nested. */ - cmp $__KERNEL_CS, 16(%rsp) + cmpq $__KERNEL_CS, 16(%rsp) jne first_nmi /* * Check the special variable on the stack to see if NMIs are * executing. */ - cmp $1, -8(%rsp) + cmpl $1, -8(%rsp) je nested_nmi /* [unhandled content-type:application/pgp-signature]
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