On Mon, Oct 05, 2015 at 05:47:53PM -0700, Andy Lutomirski wrote:
> Clearing NT is part of the prologue, whereas loading up arg6 makes
> more sense to think about as part of syscall processing. Reorder
> them.
>
> Signed-off-by: Andy Lutomirski <l...@kernel.org>
> ---
> arch/x86/entry/entry_64_compat.S | 18 +++++++++---------
> 1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/entry/entry_64_compat.S
> b/arch/x86/entry/entry_64_compat.S
> index a9360d40fb7f..aa76864a8a6b 100644
> --- a/arch/x86/entry/entry_64_compat.S
> +++ b/arch/x86/entry/entry_64_compat.S
> @@ -89,15 +89,6 @@ ENTRY(entry_SYSENTER_compat)
> sub $(10*8), %rsp /* pt_regs->r8-11, bp, bx, r12-15 not saved */
>
> /*
> - * no need to do an access_ok check here because rbp has been
> - * 32-bit zero extended
> - */
> - ASM_STAC
> -1: movl (%rbp), %ebp
> - _ASM_EXTABLE(1b, ia32_badarg)
> - ASM_CLAC
> -
> - /*
> * Sysenter doesn't filter flags, so we need to clear NT
> * ourselves. To save a few cycles, we can check whether
> * NT was set instead of doing an unconditional popfq.
> @@ -106,6 +97,15 @@ ENTRY(entry_SYSENTER_compat)
> jnz sysenter_fix_flags
> sysenter_flags_fixed:
Btw, do I see it correctly that we can save us this jumping to
sysenter_fix_flags and back to sysenter_flags_fixed? Label is jumped to
only once and the couple of insns there can be behind a JZ...
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
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