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x86/entry/64/compat: Fix SYSENTER's NT flag before user memory access

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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 <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/19eb235828b2d2a52c53459e09f2974e15e65a35.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2015-10-05 17:47:53 -07:00 • committed by Ingo Molnar
parent 04235c00b6
commit dd27f998f0
1 changed files with 9 additions and 9 deletions
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18
arch/x86/entry/entry_64_compat.S
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@ -88,15 +88,6 @@ ENTRY(entry_SYSENTER_compat)
cld
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
@ -106,6 +97,15 @@ ENTRY(entry_SYSENTER_compat)
jnz sysenter_fix_flags
sysenter_flags_fixed:
/*
* 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
orl $TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS)
testl $_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)
jnz sysenter_tracesys