powerpc/32: move MSR_PR test into EXCEPTION_PROLOG_0

In order to simplify  VMAP stack implementation, move
MSR_PR test into EXCEPTION_PROLOG_0.

This requires to not modify cr0 between EXCEPTION_PROLOG_0
and EXCEPTION_PROLOG_1.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/5c8b5bba692b92654dbd363a229a1ba91db725bb.1576916812.git.christophe.leroy@c-s.fr

arch/powerpc/kernel/head_32.h

@@ -19,12 +19,12 @@
 .macro EXCEPTION_PROLOG_0
 	mtspr	SPRN_SPRG_SCRATCH0,r10
 	mtspr	SPRN_SPRG_SCRATCH1,r11
+	mfspr	r11, SPRN_SRR1		/* check whether user or kernel */
 	mfcr	r10
+	andi.	r11, r11, MSR_PR
 .endm
 
 .macro EXCEPTION_PROLOG_1
-	mfspr	r11,SPRN_SRR1		/* check whether user or kernel */
-	andi.	r11,r11,MSR_PR
 	tophys(r11,r1)			/* use tophys(r1) if kernel */
 	beq	1f
 	mfspr	r11,SPRN_SPRG_THREAD

arch/powerpc/kernel/head_8xx.S

@@ -497,8 +497,8 @@ InstructionTLBError:
 DataTLBError:
 	EXCEPTION_PROLOG_0
 	mfspr	r11, SPRN_DAR
-	cmpwi	cr0, r11, RPN_PATTERN
-	beq-	FixupDAR	/* must be a buggy dcbX, icbi insn. */
+	cmpwi	cr1, r11, RPN_PATTERN
+	beq-	cr1, FixupDAR	/* must be a buggy dcbX, icbi insn. */
 DARFixed:/* Return from dcbx instruction bug workaround */
 	EXCEPTION_PROLOG_1
 	EXCEPTION_PROLOG_2
@@ -531,9 +531,9 @@ DARFixed:/* Return from dcbx instruction bug workaround */
 DataBreakpoint:
 	EXCEPTION_PROLOG_0
 	mfspr	r11, SPRN_SRR0
-	cmplwi	cr0, r11, (.Ldtlbie - PAGE_OFFSET)@l
+	cmplwi	cr1, r11, (.Ldtlbie - PAGE_OFFSET)@l
 	cmplwi	cr7, r11, (.Litlbie - PAGE_OFFSET)@l
-	beq-	cr0, 11f
+	beq-	cr1, 11f
 	beq-	cr7, 11f
 	EXCEPTION_PROLOG_1
 	EXCEPTION_PROLOG_2
@@ -578,9 +578,9 @@ FixupDAR:/* Entry point for dcbx workaround. */
 	mfspr	r10, SPRN_SRR0
 	mtspr	SPRN_MD_EPN, r10
 	rlwinm	r11, r10, 16, 0xfff8
-	cmpli	cr0, r11, PAGE_OFFSET@h
+	cmpli	cr1, r11, PAGE_OFFSET@h
 	mfspr	r11, SPRN_M_TWB	/* Get level 1 table */
-	blt+	3f
+	blt+	cr1, 3f
 	rlwinm	r11, r10, 16, 0xfff8
 
 0:	cmpli	cr7, r11, (PAGE_OFFSET + 0x1800000)@h
@@ -595,7 +595,7 @@ FixupDAR:/* Entry point for dcbx workaround. */
 3:
 	lwz	r11, (swapper_pg_dir-PAGE_OFFSET)@l(r11)	/* Get the level 1 entry */
 	mtspr	SPRN_MD_TWC, r11
-	mtcr	r11
+	mtcrf	0x01, r11
 	mfspr	r11, SPRN_MD_TWC
 	lwz	r11, 0(r11)	/* Get the pte */
 	bt	28,200f		/* bit 28 = Large page (8M) */
@@ -608,16 +608,16 @@ FixupDAR:/* Entry point for dcbx workaround. */
  * no need to include them here */
 	xoris	r10, r11, 0x7c00	/* check if major OP code is 31 */
 	rlwinm	r10, r10, 0, 21, 5
-	cmpwi	cr0, r10, 2028	/* Is dcbz? */
-	beq+	142f
-	cmpwi	cr0, r10, 940	/* Is dcbi? */
-	beq+	142f
-	cmpwi	cr0, r10, 108	/* Is dcbst? */
-	beq+	144f		/* Fix up store bit! */
-	cmpwi	cr0, r10, 172	/* Is dcbf? */
-	beq+	142f
-	cmpwi	cr0, r10, 1964	/* Is icbi? */
-	beq+	142f
+	cmpwi	cr1, r10, 2028	/* Is dcbz? */
+	beq+	cr1, 142f
+	cmpwi	cr1, r10, 940	/* Is dcbi? */
+	beq+	cr1, 142f
+	cmpwi	cr1, r10, 108	/* Is dcbst? */
+	beq+	cr1, 144f		/* Fix up store bit! */
+	cmpwi	cr1, r10, 172	/* Is dcbf? */
+	beq+	cr1, 142f
+	cmpwi	cr1, r10, 1964	/* Is icbi? */
+	beq+	cr1, 142f
 141:	mfspr	r10,SPRN_M_TW
 	b	DARFixed	/* Nope, go back to normal TLB processing */
 
@@ -676,8 +676,9 @@ FixupDAR:/* Entry point for dcbx workaround. */
 	add	r10, r10, r30	;b	151f
 	add	r10, r10, r31
 151:
-	rlwinm. r11,r11,19,24,28	/* offset into jump table for reg RA */
-	beq	152f			/* if reg RA is zero, don't add it */
+	rlwinm	r11,r11,19,24,28	/* offset into jump table for reg RA */
+	cmpwi	cr1, r11, 0
+	beq	cr1, 152f		/* if reg RA is zero, don't add it */
 	addi	r11, r11, 150b@l	/* add start of table */
 	mtctr	r11			/* load ctr with jump address */
 	rlwinm	r11,r11,0,16,10		/* make sure we don't execute this more than once */