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| author | Brian Gerst <brgerst@gmail.com> | 2009-11-25 11:17:36 -0500 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-11-26 10:44:30 +0100 |
| commit | 8ec6993d9f7d961014af970ded57542961fe9ad9 (patch) | |
| tree | 62f5eb8402c4cdda753161541f8106c29953d325 /arch/x86/kernel/head_64.S | |
| parent | 64b028b22616946a05bf9580f7f7f7ee2ac070b4 (diff) | |
| download | linux-8ec6993d9f7d961014af970ded57542961fe9ad9.tar.gz linux-8ec6993d9f7d961014af970ded57542961fe9ad9.tar.bz2 linux-8ec6993d9f7d961014af970ded57542961fe9ad9.zip | |
x86, 64-bit: Set data segments to null after switching to 64-bit mode
This prevents kernel threads from inheriting non-null segment
selectors, and causing optimizations in __switch_to() to be
ineffective.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Cc: Tim Blechmann <tim@klingt.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Jan Beulich <JBeulich@novell.com>
LKML-Reference: <1259165856-3512-1-git-send-email-brgerst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/head_64.S')
| -rw-r--r-- | arch/x86/kernel/head_64.S | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 26406601031c..17ba9ecf27c5 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -212,8 +212,8 @@ ENTRY(secondary_startup_64) */ lgdt early_gdt_descr(%rip) - /* set up data segments. actually 0 would do too */ - movl $__KERNEL_DS,%eax + /* set up data segments */ + xorl %eax,%eax movl %eax,%ds movl %eax,%ss movl %eax,%es |