summaryrefslogtreecommitdiff
path: root/arch/x86/kernel/head_32.S
diff options
context:
space:
mode:
authorAndy Lutomirski <luto@kernel.org>2017-07-28 06:00:31 -0700
committerIngo Molnar <mingo@kernel.org>2017-07-30 12:04:40 +0200
commit630c1863bc1c6c0ac33e5134bec7bdf7941c28c8 (patch)
tree5d8a563db6790efbc6d5f5506558166d7c4da7c5 /arch/x86/kernel/head_32.S
parent385eca8f277c4c34f361a4c3a088fd876d29ae21 (diff)
x86/traps: Don't clear segment high bits in early_idt_handler_common()
Now that pt_regs defines the segment fields as 16-bit, there's no need to sanitize the values. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bpetkov@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/head_32.S')
-rw-r--r--arch/x86/kernel/head_32.S20
1 files changed, 8 insertions, 12 deletions
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index 1f85ee8f9439..0332664eb158 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -457,12 +457,9 @@ early_idt_handler_common:
/* The vector number is in pt_regs->gs */
cld
- pushl %fs /* pt_regs->fs */
- movw $0, 2(%esp) /* clear high bits (some CPUs leave garbage) */
- pushl %es /* pt_regs->es */
- movw $0, 2(%esp) /* clear high bits (some CPUs leave garbage) */
- pushl %ds /* pt_regs->ds */
- movw $0, 2(%esp) /* clear high bits (some CPUs leave garbage) */
+ pushl %fs /* pt_regs->fs (__fsh varies by model) */
+ pushl %es /* pt_regs->es (__esh varies by model) */
+ pushl %ds /* pt_regs->ds (__dsh varies by model) */
pushl %eax /* pt_regs->ax */
pushl %ebp /* pt_regs->bp */
pushl %edi /* pt_regs->di */
@@ -479,9 +476,8 @@ early_idt_handler_common:
/* Load the vector number into EDX */
movl PT_GS(%esp), %edx
- /* Load GS into pt_regs->gs and clear high bits */
+ /* Load GS into pt_regs->gs (and maybe clobber __gsh) */
movw %gs, PT_GS(%esp)
- movw $0, PT_GS+2(%esp)
movl %esp, %eax /* args are pt_regs (EAX), trapnr (EDX) */
call early_fixup_exception
@@ -493,10 +489,10 @@ early_idt_handler_common:
popl %edi /* pt_regs->di */
popl %ebp /* pt_regs->bp */
popl %eax /* pt_regs->ax */
- popl %ds /* pt_regs->ds */
- popl %es /* pt_regs->es */
- popl %fs /* pt_regs->fs */
- popl %gs /* pt_regs->gs */
+ popl %ds /* pt_regs->ds (always ignores __dsh) */
+ popl %es /* pt_regs->es (always ignores __esh) */
+ popl %fs /* pt_regs->fs (always ignores __fsh) */
+ popl %gs /* pt_regs->gs (always ignores __gsh) */
decl %ss:early_recursion_flag
addl $4, %esp /* pop pt_regs->orig_ax */
iret