summaryrefslogtreecommitdiff
path: root/arch/x86/entry
diff options
context:
space:
mode:
authorAndy Lutomirski <luto@kernel.org>2016-04-26 12:23:27 -0700
committerIngo Molnar <mingo@kernel.org>2016-04-29 11:56:41 +0200
commitb038c842b385f1470f991078e71b7c5b084a7341 (patch)
tree01b851aac2b3fd9d83a39cdfe8673bd0015f0b04 /arch/x86/entry
parent45e876f794e8e566bf827c25ef0791875081724f (diff)
x86/segments/64: When load_gs_index fails, clear the base
On AMD CPUs, a failed load_gs_base currently may not clear the FS base. Fix it. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1a6c4d3a8a4e7be79ba448b42685e0321d50c14c.1461698311.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/entry')
-rw-r--r--arch/x86/entry/entry_64.S6
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 1693c17dbf81..6344629ae1ce 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -794,6 +794,12 @@ END(native_load_gs_index)
/* running with kernelgs */
bad_gs:
SWAPGS /* switch back to user gs */
+.macro ZAP_GS
+ /* This can't be a string because the preprocessor needs to see it. */
+ movl $__USER_DS, %eax
+ movl %eax, %gs
+.endm
+ ALTERNATIVE "", "ZAP_GS", X86_BUG_NULL_SEG
xorl %eax, %eax
movl %eax, %gs
jmp 2b