diff options
| author | H. Peter Anvin <hpa@zytor.com> | 2014-05-04 10:36:22 -0700 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2014-05-04 12:27:37 -0700 |
| commit | 34273f41d57ee8d854dcd2a1d754cbb546cb548f (patch) | |
| tree | 0f3fee911ac04263045d3c1557dd5ba452dc9658 /arch/x86/kernel/entry_64.S | |
| parent | 197725de65477bc8509b41388157c1a2283542bb (diff) | |
x86, espfix: Make it possible to disable 16-bit support
Embedded systems, which may be very memory-size-sensitive, are
extremely unlikely to ever encounter any 16-bit software, so make it
a CONFIG_EXPERT option to turn off support for any 16-bit software
whatsoever.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1398816946-3351-1-git-send-email-hpa@linux.intel.com
Diffstat (limited to 'arch/x86/kernel/entry_64.S')
| -rw-r--r-- | arch/x86/kernel/entry_64.S | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index bffaa986cafc..da0b9bdcc32e 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -1045,8 +1045,10 @@ irq_return: * Are we returning to a stack segment from the LDT? Note: in * 64-bit mode SS:RSP on the exception stack is always valid. */ +#ifdef CONFIG_X86_ESPFIX64 testb $4,(SS-RIP)(%rsp) jnz irq_return_ldt +#endif irq_return_iret: INTERRUPT_RETURN @@ -1058,6 +1060,7 @@ ENTRY(native_iret) _ASM_EXTABLE(native_iret, bad_iret) #endif +#ifdef CONFIG_X86_ESPFIX64 irq_return_ldt: pushq_cfi %rax pushq_cfi %rdi @@ -1081,6 +1084,7 @@ irq_return_ldt: movq %rax,%rsp popq_cfi %rax jmp irq_return_iret +#endif .section .fixup,"ax" bad_iret: @@ -1152,6 +1156,7 @@ END(common_interrupt) * modify the stack to make it look like we just entered * the #GP handler from user space, similar to bad_iret. */ +#ifdef CONFIG_X86_ESPFIX64 ALIGN __do_double_fault: XCPT_FRAME 1 RDI+8 @@ -1177,6 +1182,9 @@ __do_double_fault: retq CFI_ENDPROC END(__do_double_fault) +#else +# define __do_double_fault do_double_fault +#endif /* * End of kprobes section |