aboutsummaryrefslogtreecommitdiff
path: root/arch/powerpc/kernel/entry_64.S
diff options
context:
space:
mode:
authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2012-03-02 11:33:52 +1100
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2012-03-09 10:55:20 +1100
commitd9ada91ae2969ae6b6dc3574fd08a6ebda5df766 (patch)
treea4509657892acb0b853760d6d26729a913a5fc2b /arch/powerpc/kernel/entry_64.S
parent9424fabf8617c15e18a5ffd29bc3bcfa36620473 (diff)
downloadlinaro-lsk-d9ada91ae2969ae6b6dc3574fd08a6ebda5df766.tar.gz
powerpc: Replace mfmsr instructions with load from PACA kernel_msr field
On 64-bit, the mfmsr instruction can be quite slow, slower than loading a field from the cache-hot PACA, which happens to already contain the value we want in most cases. 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.S14
1 files changed, 5 insertions, 9 deletions
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index cc030b73174..c513beb78b3 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -557,10 +557,8 @@ _GLOBAL(ret_from_except_lite)
#ifdef CONFIG_PPC_BOOK3E
wrteei 0
#else
- mfmsr r10 /* Get current interrupt state */
- rldicl r9,r10,48,1 /* clear MSR_EE */
- rotldi r9,r9,16
- mtmsrd r9,1 /* Update machine state */
+ ld r10,PACAKMSR(r13) /* Get kernel MSR without EE */
+ mtmsrd r10,1 /* Update machine state */
#endif /* CONFIG_PPC_BOOK3E */
#ifdef CONFIG_PREEMPT
@@ -625,8 +623,8 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
* userspace and we take an exception after restoring r13,
* we end up corrupting the userspace r13 value.
*/
- mfmsr r4
- andc r4,r4,r0 /* r0 contains MSR_RI here */
+ ld r4,PACAKMSR(r13) /* Get kernel MSR without EE */
+ andc r4,r4,r0 /* r0 contains MSR_RI here */
mtmsrd r4,1
/*
@@ -686,9 +684,7 @@ do_work:
#ifdef CONFIG_PPC_BOOK3E
wrteei 0
#else
- mfmsr r10
- rldicl r10,r10,48,1
- rotldi r10,r10,16
+ ld r10,PACAKMSR(r13) /* Get kernel MSR without EE */
mtmsrd r10,1
#endif /* CONFIG_PPC_BOOK3E */
li r0,0