diff options
| author | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2012-03-02 11:33:52 +1100 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2012-03-09 10:55:20 +1100 |
| commit | d9ada91ae2969ae6b6dc3574fd08a6ebda5df766 (patch) | |
| tree | a4509657892acb0b853760d6d26729a913a5fc2b /arch/powerpc/kernel/entry_64.S | |
| parent | 9424fabf8617c15e18a5ffd29bc3bcfa36620473 (diff) | |
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.S | 14 |
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 |