diff options
| author | Andy Lutomirski <luto@kernel.org> | 2016-12-01 09:26:42 -0800 |
|---|---|---|
| committer | Mister Oyster <oysterized@gmail.com> | 2017-04-11 10:57:46 +0200 |
| commit | e7ee827d947cb8bb731c709fae3e863f6e5cea97 (patch) | |
| tree | 52fb03838510e436e425e8ba09a7320df32ef629 /arch | |
| parent | e6de0f552a2a4a967fa473d70042ffee375816bb (diff) | |
x86/traps: Ignore high word of regs->cs in early_idt_handler_common
This is a backport of:
commit fc0e81b2bea0ebceb71889b61d2240856141c9ee upstream
On the 80486 DX, it seems that some exceptions may leave garbage in
the high bits of CS. This causes sporadic failures in which
early_fixup_exception() refuses to fix up an exception.
As far as I can tell, this has been buggy for a long time, but the
problem seems to have been exacerbated by commits:
1e02ce4cccdc ("x86: Store a per-cpu shadow copy of CR4")
e1bfc11c5a6f ("x86/init: Fix cr4_init_shadow() on CR4-less machines")
This appears to have broken for as long as we've had early
exception handling.
[ This backport should apply to kernels from 3.4 - 4.5. ]
Fixes: 4c5023a3fa2e ("x86-32: Handle exception table entries during early boot")
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: stable@vger.kernel.org
Reported-by: Matthew Whitehead <tedheadster@gmail.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/head_32.S | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S index 8060c8b95..b7e330c57 100644 --- a/arch/x86/kernel/head_32.S +++ b/arch/x86/kernel/head_32.S @@ -586,7 +586,7 @@ early_idt_handler_common: movl %eax,%ds movl %eax,%es - cmpl $(__KERNEL_CS),32(%esp) + cmpw $(__KERNEL_CS),32(%esp) jne 10f leal 28(%esp),%eax # Pointer to %eip |