powerpc/e500: free r10 for FIND_PTE

Move r13 load after the call to FIND_PTE, and use r13 instead of r10 for
storing fault address.  This will allow using r10 freely in FIND_PTE in
following patch to handle hugepage size.

Link: https://lkml.kernel.org/r/a3ee563ad5b13c891a15d3aae6c136c44ce8aa63.1719928057.git.christophe.leroy@csgroup.euSigned-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

arch/powerpc/kernel/head_85xx.S

@@ -294,9 +294,10 @@ set_ivor:
 /* Macros to hide the PTE size differences
  *
  * FIND_PTE -- walks the page tables given EA & pgdir pointer
- *   r10 -- EA of fault
+ *   r10 -- free
  *   r11 -- PGDIR pointer
  *   r12 -- free
+ *   r13 -- EA of fault
  *   label 2: is the bailout case
  *
  * if we find the pte (fall through):
@@ -307,7 +308,7 @@ set_ivor:
 #ifdef CONFIG_PTE_64BIT
 #ifdef CONFIG_HUGETLB_PAGE
 #define FIND_PTE	\
-	rlwinm	r12, r10, 14, 18, 28;	/* Compute pgdir/pmd offset */	\
+	rlwinm	r12, r13, 14, 18, 28;	/* Compute pgdir/pmd offset */	\
 	add	r12, r11, r12;						\
 	lwz	r11, 4(r12);		/* Get pgd/pmd entry */		\
 	rlwinm.	r12, r11, 0, 0, 20;	/* Extract pt base address */	\
@@ -317,26 +318,26 @@ set_ivor:
 	andi.	r10, r11, HUGEPD_SHIFT_MASK@l; /* extract size field */	\
 	xor	r12, r10, r11;		/* drop size bits from pointer */ \
 	b	1001f;							\
-1000:	rlwimi	r12, r10, 23, 20, 28;	/* Compute pte address */	\
+1000:	rlwimi	r12, r13, 23, 20, 28;	/* Compute pte address */	\
 	li	r10, 0;			/* clear r10 */			\
 1001:	lwz	r11, 4(r12);		/* Get pte entry */
 #else
 #define FIND_PTE	\
-	rlwinm	r12, r10, 14, 18, 28;	/* Compute pgdir/pmd offset */	\
+	rlwinm	r12, r13, 14, 18, 28;	/* Compute pgdir/pmd offset */	\
 	add	r12, r11, r12;						\
 	lwz	r11, 4(r12);		/* Get pgd/pmd entry */		\
 	rlwinm.	r12, r11, 0, 0, 20;	/* Extract pt base address */	\
 	beq	2f;			/* Bail if no table */		\
-	rlwimi	r12, r10, 23, 20, 28;	/* Compute pte address */	\
+	rlwimi	r12, r13, 23, 20, 28;	/* Compute pte address */	\
 	lwz	r11, 4(r12);		/* Get pte entry */
 #endif /* HUGEPAGE */
 #else /* !PTE_64BIT */
 #define FIND_PTE	\
-	rlwimi	r11, r10, 12, 20, 29;	/* Create L1 (pgdir/pmd) address */	\
+	rlwimi	r11, r13, 12, 20, 29;	/* Create L1 (pgdir/pmd) address */	\
 	lwz	r11, 0(r11);		/* Get L1 entry */			\
 	rlwinm.	r12, r11, 0, 0, 19;	/* Extract L2 (pte) base address */	\
 	beq	2f;			/* Bail if no table */			\
-	rlwimi	r12, r10, 22, 20, 29;	/* Compute PTE address */		\
+	rlwimi	r12, r13, 22, 20, 29;	/* Compute PTE address */		\
 	lwz	r11, 0(r12);		/* Get Linux PTE */
 #endif
 
@@ -443,13 +444,13 @@ START_BTB_FLUSH_SECTION
 	BTB_FLUSH(r10)
 1:
 END_BTB_FLUSH_SECTION
-	mfspr	r10, SPRN_DEAR		/* Get faulting address */
+	mfspr	r13, SPRN_DEAR		/* Get faulting address */
 
 	/* If we are faulting a kernel address, we have to use the
 	 * kernel page tables.
 	 */
 	lis	r11, PAGE_OFFSET@h
-	cmplw	5, r10, r11
+	cmplw	5, r13, r11
 	blt	5, 3f
 	lis	r11, swapper_pg_dir@h
 	ori	r11, r11, swapper_pg_dir@l
@@ -472,14 +473,14 @@ END_BTB_FLUSH_SECTION
 #endif
 
 4:
+	FIND_PTE
+
 #ifdef CONFIG_PTE_64BIT
 	li	r13,_PAGE_PRESENT|_PAGE_BAP_SR
 	oris	r13,r13,_PAGE_ACCESSED@h
 #else
 	li	r13,_PAGE_PRESENT|_PAGE_READ|_PAGE_ACCESSED
 #endif
-
-	FIND_PTE
 	andc.	r13,r13,r11		/* Check permission */
 
 #ifdef CONFIG_PTE_64BIT
@@ -536,13 +537,13 @@ START_BTB_FLUSH_SECTION
 1:
 END_BTB_FLUSH_SECTION
 
-	mfspr	r10, SPRN_SRR0		/* Get faulting address */
+	mfspr	r13, SPRN_SRR0		/* Get faulting address */
 
 	/* If we are faulting a kernel address, we have to use the
 	 * kernel page tables.
 	 */
 	lis	r11, PAGE_OFFSET@h
-	cmplw	5, r10, r11
+	cmplw	5, r13, r11
 	blt	5, 3f
 	lis	r11, swapper_pg_dir@h
 	ori	r11, r11, swapper_pg_dir@l
@@ -551,6 +552,7 @@ END_BTB_FLUSH_SECTION
 	rlwinm	r12,r12,0,16,1
 	mtspr	SPRN_MAS1,r12
 
+	FIND_PTE
 	/* Make up the required permissions for kernel code */
 #ifdef CONFIG_PTE_64BIT
 	li	r13,_PAGE_PRESENT | _PAGE_BAP_SX
@@ -571,6 +573,7 @@ END_BTB_FLUSH_SECTION
 	beq	2f			/* KUAP fault */
 #endif
 
+	FIND_PTE
 	/* Make up the required permissions for user code */
 #ifdef CONFIG_PTE_64BIT
 	li	r13,_PAGE_PRESENT | _PAGE_BAP_UX
@@ -580,7 +583,6 @@ END_BTB_FLUSH_SECTION
 #endif
 
 4:
-	FIND_PTE
 	andc.	r13,r13,r11		/* Check permission */
 
 #ifdef CONFIG_PTE_64BIT