diff options
| author | Andy Lutomirski <luto@kernel.org> | 2017-07-28 06:00:31 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-07-30 12:04:40 +0200 |
| commit | 630c1863bc1c6c0ac33e5134bec7bdf7941c28c8 (patch) | |
| tree | 5d8a563db6790efbc6d5f5506558166d7c4da7c5 /arch/x86/kernel/head_32.S | |
| parent | 385eca8f277c4c34f361a4c3a088fd876d29ae21 (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.S | 20 |
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 |