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| author | Anton Blanchard <anton@samba.org> | 2012-05-29 12:22:00 +0000 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2012-07-03 14:14:43 +1000 |
| commit | ac1dc36558da25934f83a2871b9e70239a987351 (patch) | |
| tree | 155d119bd3534b9f324e02a0454d0fbba58d6a88 /arch/powerpc/kernel/entry_64.S | |
| parent | a9514dc69d5c4f5d6d9e4b8eed40172abd150c61 (diff) | |
| download | lwn-ac1dc36558da25934f83a2871b9e70239a987351.tar.gz lwn-ac1dc36558da25934f83a2871b9e70239a987351.zip | |
powerpc: Clear RI and EE at the same time in system call exit
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>
Diffstat (limited to 'arch/powerpc/kernel/entry_64.S')
| -rw-r--r-- | arch/powerpc/kernel/entry_64.S | 25 |
1 files changed, 13 insertions, 12 deletions
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 5971c85df136..cf38a17ab28a 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -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. */ |