powerpc/mm: Used free register to save a few cycles in SW TLB miss handling

Now that r0 is free we can keep the value of I/DMISS in r3 and not reload
it before doing the tlbli/d.  This saves us a few cycles in the fast path
case.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index f37df0c..58dcc7c 100644 (file)
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -498,28 +498,27 @@ InstructionTLBMiss:
        rlwinm. r2,r2,0,0,19            /* extract address of pte page */
        beq-    InstructionAddressInvalid       /* return if no mapping */
        rlwimi  r2,r3,22,20,29          /* insert next 10 bits of address */
-       lwz     r3,0(r2)                /* get linux-style pte */
-       andc.   r1,r1,r3                /* check access & ~permission */
+       lwz     r0,0(r2)                /* get linux-style pte */
+       andc.   r1,r1,r0                /* check access & ~permission */
        bne-    InstructionAddressInvalid /* return if access not permitted */
-       ori     r3,r3,_PAGE_ACCESSED    /* set _PAGE_ACCESSED in pte */
+       ori     r0,r0,_PAGE_ACCESSED    /* set _PAGE_ACCESSED in pte */
        /*
         * NOTE! We are assuming this is not an SMP system, otherwise
         * we would need to update the pte atomically with lwarx/stwcx.
         */
-       stw     r3,0(r2)                /* update PTE (accessed bit) */
+       stw     r0,0(r2)                /* update PTE (accessed bit) */
        /* Convert linux-style PTE to low word of PPC-style PTE */
-       rlwinm  r1,r3,32-10,31,31       /* _PAGE_RW -> PP lsb */
-       rlwinm  r2,r3,32-7,31,31        /* _PAGE_DIRTY -> PP lsb */
+       rlwinm  r1,r0,32-10,31,31       /* _PAGE_RW -> PP lsb */
+       rlwinm  r2,r0,32-7,31,31        /* _PAGE_DIRTY -> PP lsb */
        and     r1,r1,r2                /* writable if _RW and _DIRTY */
-       rlwimi  r3,r3,32-1,30,30        /* _PAGE_USER -> PP msb */
-       rlwimi  r3,r3,32-1,31,31        /* _PAGE_USER -> PP lsb */
+       rlwimi  r0,r0,32-1,30,30        /* _PAGE_USER -> PP msb */
+       rlwimi  r0,r0,32-1,31,31        /* _PAGE_USER -> PP lsb */
        ori     r1,r1,0xe04             /* clear out reserved bits */
-       andc    r1,r3,r1                /* PP = user? (rw&dirty? 2: 3): 0 */
+       andc    r1,r0,r1                /* PP = user? (rw&dirty? 2: 3): 0 */
 BEGIN_FTR_SECTION
        rlwinm  r1,r1,0,~_PAGE_COHERENT /* clear M (coherence not required) */
 END_FTR_SECTION_IFCLR(CPU_FTR_NEED_COHERENT)
        mtspr   SPRN_RPA,r1
-       mfspr   r3,SPRN_IMISS
        tlbli   r3
        mfspr   r3,SPRN_SRR1            /* Need to restore CR0 */
        mtcrf   0x80,r3
@@ -573,28 +572,27 @@ DataLoadTLBMiss:
        rlwinm. r2,r2,0,0,19            /* extract address of pte page */
        beq-    DataAddressInvalid      /* return if no mapping */
        rlwimi  r2,r3,22,20,29          /* insert next 10 bits of address */
-       lwz     r3,0(r2)                /* get linux-style pte */
-       andc.   r1,r1,r3                /* check access & ~permission */
+       lwz     r0,0(r2)                /* get linux-style pte */
+       andc.   r1,r1,r0                /* check access & ~permission */
        bne-    DataAddressInvalid      /* return if access not permitted */
-       ori     r3,r3,_PAGE_ACCESSED    /* set _PAGE_ACCESSED in pte */
+       ori     r0,r0,_PAGE_ACCESSED    /* set _PAGE_ACCESSED in pte */
        /*
         * NOTE! We are assuming this is not an SMP system, otherwise
         * we would need to update the pte atomically with lwarx/stwcx.
         */
-       stw     r3,0(r2)                /* update PTE (accessed bit) */
+       stw     r0,0(r2)                /* update PTE (accessed bit) */
        /* Convert linux-style PTE to low word of PPC-style PTE */
-       rlwinm  r1,r3,32-10,31,31       /* _PAGE_RW -> PP lsb */
-       rlwinm  r2,r3,32-7,31,31        /* _PAGE_DIRTY -> PP lsb */
+       rlwinm  r1,r0,32-10,31,31       /* _PAGE_RW -> PP lsb */
+       rlwinm  r2,r0,32-7,31,31        /* _PAGE_DIRTY -> PP lsb */
        and     r1,r1,r2                /* writable if _RW and _DIRTY */
-       rlwimi  r3,r3,32-1,30,30        /* _PAGE_USER -> PP msb */
-       rlwimi  r3,r3,32-1,31,31        /* _PAGE_USER -> PP lsb */
+       rlwimi  r0,r0,32-1,30,30        /* _PAGE_USER -> PP msb */
+       rlwimi  r0,r0,32-1,31,31        /* _PAGE_USER -> PP lsb */
        ori     r1,r1,0xe04             /* clear out reserved bits */
-       andc    r1,r3,r1                /* PP = user? (rw&dirty? 2: 3): 0 */
+       andc    r1,r0,r1                /* PP = user? (rw&dirty? 2: 3): 0 */
 BEGIN_FTR_SECTION
        rlwinm  r1,r1,0,~_PAGE_COHERENT /* clear M (coherence not required) */
 END_FTR_SECTION_IFCLR(CPU_FTR_NEED_COHERENT)
        mtspr   SPRN_RPA,r1
-       mfspr   r3,SPRN_DMISS
        tlbld   r3
        mfspr   r3,SPRN_SRR1            /* Need to restore CR0 */
        mtcrf   0x80,r3
@@ -646,24 +644,23 @@ DataStoreTLBMiss:
        rlwinm. r2,r2,0,0,19            /* extract address of pte page */
        beq-    DataAddressInvalid      /* return if no mapping */
        rlwimi  r2,r3,22,20,29          /* insert next 10 bits of address */
-       lwz     r3,0(r2)                /* get linux-style pte */
-       andc.   r1,r1,r3                /* check access & ~permission */
+       lwz     r0,0(r2)                /* get linux-style pte */
+       andc.   r1,r1,r0                /* check access & ~permission */
        bne-    DataAddressInvalid      /* return if access not permitted */
-       ori     r3,r3,_PAGE_ACCESSED|_PAGE_DIRTY
+       ori     r0,r0,_PAGE_ACCESSED|_PAGE_DIRTY
        /*
         * NOTE! We are assuming this is not an SMP system, otherwise
         * we would need to update the pte atomically with lwarx/stwcx.
         */
-       stw     r3,0(r2)                /* update PTE (accessed/dirty bits) */
+       stw     r0,0(r2)                /* update PTE (accessed/dirty bits) */
        /* Convert linux-style PTE to low word of PPC-style PTE */
-       rlwimi  r3,r3,32-1,30,30        /* _PAGE_USER -> PP msb */
+       rlwimi  r0,r0,32-1,30,30        /* _PAGE_USER -> PP msb */
        li      r1,0xe05                /* clear out reserved bits & PP lsb */
-       andc    r1,r3,r1                /* PP = user? 2: 0 */
+       andc    r1,r0,r1                /* PP = user? 2: 0 */
 BEGIN_FTR_SECTION
        rlwinm  r1,r1,0,~_PAGE_COHERENT /* clear M (coherence not required) */
 END_FTR_SECTION_IFCLR(CPU_FTR_NEED_COHERENT)
        mtspr   SPRN_RPA,r1
-       mfspr   r3,SPRN_DMISS
        tlbld   r3
        mfspr   r3,SPRN_SRR1            /* Need to restore CR0 */
        mtcrf   0x80,r3