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powerpc: Clear RI and EE at the same time in system call exit

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mtmsrd is an expensive instruction, we save a few cycles by
doing it once instead of twice.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Anton Blanchard 2012-05-29 12:22:00 +00:00 committed by Benjamin Herrenschmidt
parent a9514dc69d
commit ac1dc36558
1 changed files with 13 additions and 12 deletions
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25
arch/powerpc/kernel/entry_64.S
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@ -197,7 +197,16 @@ syscall_exit:
wrteei 0
#else
ld r10,PACAKMSR(r13)
mtmsrd r10,1
/*
* For performance reasons we clear RI the same time that we
* clear EE. We only need to clear RI just before we restore r13
* below, but batching it with EE saves us one expensive mtmsrd call.
* We have to be careful to restore RI if we branch anywhere from
* here (eg syscall_exit_work).
*/
li r9,MSR_RI
andc r11,r10,r9
mtmsrd r11,1
#endif /* CONFIG_PPC_BOOK3E */
ld r9,TI_FLAGS(r12)
@ -214,17 +223,6 @@ BEGIN_FTR_SECTION
END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
andi. r6,r8,MSR_PR
ld r4,_LINK(r1)
/*
* Clear RI before restoring r13. If we are returning to
* userspace and we take an exception after restoring r13,
* we end up corrupting the userspace r13 value.
*/
#ifdef CONFIG_PPC_BOOK3S
/* No MSR:RI on BookE */
li r12,MSR_RI
andc r11,r10,r12
mtmsrd r11,1 /* clear MSR.RI */
#endif /* CONFIG_PPC_BOOK3S */
beq- 1f
ACCOUNT_CPU_USER_EXIT(r11, r12)
@ -271,6 +269,9 @@ syscall_enosys:
b syscall_exit
syscall_exit_work:
#ifdef CONFIG_PPC_BOOK3S
mtmsrd r10,1 /* Restore RI */
#endif
/* If TIF_RESTOREALL is set, don't scribble on either r3 or ccr.
If TIF_NOERROR is set, just save r3 as it is. */