powerpc/32: Refactor booke critical registers saving

Refactor booke critical registers saving into a few macros
and move it into the exception prolog directly.

Keep the dedicated transfert_to_handler entry point for the
moment allthough they are empty. They will be removed in a
later patch to reduce churn.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/269171496f1f5f22afa621695bded22976c9d48d.1615552867.git.christophe.leroy@csgroup.eu

arch/powerpc/kernel/entry_32.S

@@ -51,49 +51,16 @@
 #ifdef CONFIG_BOOKE
 	.globl	mcheck_transfer_to_handler
 mcheck_transfer_to_handler:
-	mfspr	r0,SPRN_DSRR0
-	stw	r0,_DSRR0(r11)
-	mfspr	r0,SPRN_DSRR1
-	stw	r0,_DSRR1(r11)
 	/* fall through */
 _ASM_NOKPROBE_SYMBOL(mcheck_transfer_to_handler)
 
 	.globl	debug_transfer_to_handler
 debug_transfer_to_handler:
-	mfspr	r0,SPRN_CSRR0
-	stw	r0,_CSRR0(r11)
-	mfspr	r0,SPRN_CSRR1
-	stw	r0,_CSRR1(r11)
 	/* fall through */
 _ASM_NOKPROBE_SYMBOL(debug_transfer_to_handler)
 
 	.globl	crit_transfer_to_handler
 crit_transfer_to_handler:
-#ifdef CONFIG_PPC_BOOK3E_MMU
-	mfspr	r0,SPRN_MAS0
-	stw	r0,MAS0(r11)
-	mfspr	r0,SPRN_MAS1
-	stw	r0,MAS1(r11)
-	mfspr	r0,SPRN_MAS2
-	stw	r0,MAS2(r11)
-	mfspr	r0,SPRN_MAS3
-	stw	r0,MAS3(r11)
-	mfspr	r0,SPRN_MAS6
-	stw	r0,MAS6(r11)
-#ifdef CONFIG_PHYS_64BIT
-	mfspr	r0,SPRN_MAS7
-	stw	r0,MAS7(r11)
-#endif /* CONFIG_PHYS_64BIT */
-#endif /* CONFIG_PPC_BOOK3E_MMU */
-#ifdef CONFIG_44x
-	mfspr	r0,SPRN_MMUCR
-	stw	r0,MMUCR(r11)
-#endif
-	mfspr	r0,SPRN_SRR0
-	stw	r0,_SRR0(r11)
-	mfspr	r0,SPRN_SRR1
-	stw	r0,_SRR1(r11)
-
 	/* fall through */
 _ASM_NOKPROBE_SYMBOL(crit_transfer_to_handler)
 #endif

arch/powerpc/kernel/head_booke.h

@@ -229,6 +229,36 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
 	SAVE_4GPRS(3, r11);						     \
 	SAVE_2GPRS(7, r11)
 
+#define SAVE_xSRR(xSRR)			\
+	mfspr	r0,SPRN_##xSRR##0;	\
+	stw	r0,_##xSRR##0(r1);	\
+	mfspr	r0,SPRN_##xSRR##1;	\
+	stw	r0,_##xSRR##1(r1)
+
+
+.macro SAVE_MMU_REGS
+#ifdef CONFIG_PPC_BOOK3E_MMU
+	mfspr	r0,SPRN_MAS0
+	stw	r0,MAS0(r1)
+	mfspr	r0,SPRN_MAS1
+	stw	r0,MAS1(r1)
+	mfspr	r0,SPRN_MAS2
+	stw	r0,MAS2(r1)
+	mfspr	r0,SPRN_MAS3
+	stw	r0,MAS3(r1)
+	mfspr	r0,SPRN_MAS6
+	stw	r0,MAS6(r1)
+#ifdef CONFIG_PHYS_64BIT
+	mfspr	r0,SPRN_MAS7
+	stw	r0,MAS7(r1)
+#endif /* CONFIG_PHYS_64BIT */
+#endif /* CONFIG_PPC_BOOK3E_MMU */
+#ifdef CONFIG_44x
+	mfspr	r0,SPRN_MMUCR
+	stw	r0,MMUCR(r1)
+#endif
+.endm
+
 #define CRITICAL_EXCEPTION_PROLOG(intno) \
 		EXC_LEVEL_EXCEPTION_PROLOG(CRIT, intno, SPRN_CSRR0, SPRN_CSRR1)
 #define DEBUG_EXCEPTION_PROLOG \
@@ -271,6 +301,8 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
 	START_EXCEPTION(label);						\
 	CRITICAL_EXCEPTION_PROLOG(intno);				\
 	addi	r3,r1,STACK_FRAME_OVERHEAD;				\
+	SAVE_MMU_REGS;							\
+	SAVE_xSRR(SRR);							\
 	EXC_XFER_TEMPLATE(hdlr, n+2, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), \
 			  crit_transfer_to_handler, ret_from_crit_exc)
 
@@ -280,6 +312,10 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
 	mfspr	r5,SPRN_ESR;					\
 	stw	r5,_ESR(r11);					\
 	addi	r3,r1,STACK_FRAME_OVERHEAD;			\
+	SAVE_xSRR(DSRR);					\
+	SAVE_xSRR(CSRR);					\
+	SAVE_MMU_REGS;						\
+	SAVE_xSRR(SRR);						\
 	EXC_XFER_TEMPLATE(hdlr, n+4, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), \
 			  mcheck_transfer_to_handler, ret_from_mcheck_exc)
 
@@ -363,6 +399,9 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
 2:	mfspr	r4,SPRN_DBSR;						      \
 	stw	r4,_ESR(r11);		/* DebugException takes DBSR in _ESR */\
 	addi	r3,r1,STACK_FRAME_OVERHEAD;				      \
+	SAVE_xSRR(CSRR);						      \
+	SAVE_MMU_REGS;							      \
+	SAVE_xSRR(SRR);							      \
 	EXC_XFER_TEMPLATE(DebugException, 0x2008, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), debug_transfer_to_handler, ret_from_debug_exc)
 
 #define DEBUG_CRIT_EXCEPTION						      \
@@ -417,6 +456,8 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
 2:	mfspr	r4,SPRN_DBSR;						      \
 	stw	r4,_ESR(r11);		/* DebugException takes DBSR in _ESR */\
 	addi	r3,r1,STACK_FRAME_OVERHEAD;				      \
+	SAVE_MMU_REGS;							      \
+	SAVE_xSRR(SRR);							      \
 	EXC_XFER_TEMPLATE(DebugException, 0x2002, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), crit_transfer_to_handler, ret_from_crit_exc)
 
 #define DATA_STORAGE_EXCEPTION						      \