powerpc/32: save DEAR/DAR before calling handle_page_fault

handle_page_fault() is the only function that save DAR/DEAR itself.

Save DAR/DEAR before calling handle_page_fault() to prepare for
VMAP stack which will require to save even before.
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/3a4d58d378091086f00fde42b59610c80289e120.1576916812.git.christophe.leroy@c-s.fr

arch/powerpc/kernel/entry_32.S

@@ -621,7 +621,6 @@ ppc_swapcontext:
  */
 	.globl	handle_page_fault
 handle_page_fault:
-	stw	r4,_DAR(r1)
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 #ifdef CONFIG_PPC_BOOK3S_32
 	andis.  r0,r5,DSISR_DABRMATCH@h

arch/powerpc/kernel/head_32.S

@@ -310,6 +310,7 @@ BEGIN_MMU_FTR_SECTION
 END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
 1:	lwz	r5,_DSISR(r11)		/* get DSISR value */
 	mfspr	r4,SPRN_DAR
+	stw	r4, _DAR(r11)
 	EXC_XFER_LITE(0x300, handle_page_fault)
 
 
@@ -327,6 +328,7 @@ BEGIN_MMU_FTR_SECTION
 END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
 1:	mr	r4,r12
 	andis.	r5,r9,DSISR_SRR1_MATCH_32S@h /* Filter relevant SRR1 bits */
+	stw	r4, _DAR(r11)
 	EXC_XFER_LITE(0x400, handle_page_fault)
 
 /* External interrupt */

arch/powerpc/kernel/head_40x.S

@@ -313,6 +313,7 @@ _ENTRY(saved_ksp_limit)
 	START_EXCEPTION(0x0400, InstructionAccess)
 	EXCEPTION_PROLOG
 	mr	r4,r12			/* Pass SRR0 as arg2 */
+	stw	r4, _DEAR(r11)
 	li	r5,0			/* Pass zero as arg3 */
 	EXC_XFER_LITE(0x400, handle_page_fault)
 
@@ -676,6 +677,7 @@ DataAccess:
 	mfspr	r5,SPRN_ESR		/* Grab the ESR, save it, pass arg3 */
 	stw	r5,_ESR(r11)
 	mfspr	r4,SPRN_DEAR		/* Grab the DEAR, save it, pass arg2 */
+	stw	r4, _DEAR(r11)
 	EXC_XFER_LITE(0x300, handle_page_fault)
 
 /* Other PowerPC processors, namely those derived from the 6xx-series

arch/powerpc/kernel/head_8xx.S

@@ -486,6 +486,7 @@ InstructionTLBError:
 	tlbie	r4
 	/* 0x400 is InstructionAccess exception, needed by bad_page_fault() */
 .Litlbie:
+	stw	r4, _DAR(r11)
 	EXC_XFER_LITE(0x400, handle_page_fault)
 
 /* This is the data TLB error on the MPC8xx.  This could be due to
@@ -504,6 +505,7 @@ DARFixed:/* Return from dcbx instruction bug workaround */
 	mfspr	r5,SPRN_DSISR
 	stw	r5,_DSISR(r11)
 	mfspr	r4,SPRN_DAR
+	stw	r4, _DAR(r11)
 	andis.	r10,r5,DSISR_NOHPTE@h
 	beq+	.Ldtlbie
 	tlbie	r4

arch/powerpc/kernel/head_booke.h

@@ -467,6 +467,7 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
 	mfspr	r5,SPRN_ESR;		/* Grab the ESR and save it */	      \
 	stw	r5,_ESR(r11);						      \
 	mfspr	r4,SPRN_DEAR;		/* Grab the DEAR */		      \
+	stw	r4, _DEAR(r11);						      \
 	EXC_XFER_LITE(0x0300, handle_page_fault)
 
 #define INSTRUCTION_STORAGE_EXCEPTION					      \
@@ -475,6 +476,7 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
 	mfspr	r5,SPRN_ESR;		/* Grab the ESR and save it */	      \
 	stw	r5,_ESR(r11);						      \
 	mr      r4,r12;                 /* Pass SRR0 as arg2 */		      \
+	stw	r4, _DEAR(r11);						      \
 	li      r5,0;                   /* Pass zero as arg3 */		      \
 	EXC_XFER_LITE(0x0400, handle_page_fault)
 

arch/powerpc/kernel/head_fsl_booke.S

@@ -378,6 +378,7 @@ interrupt_base:
 	mfspr	r4,SPRN_DEAR		/* Grab the DEAR, save it, pass arg2 */
 	andis.	r10,r5,(ESR_ILK|ESR_DLK)@h
 	bne	1f
+	stw	r4, _DEAR(r11)
 	EXC_XFER_LITE(0x0300, handle_page_fault)
 1:
 	addi	r3,r1,STACK_FRAME_OVERHEAD