[PATCH v3 34/41] powerpc/32: Save remaining registers in exception prolog

[Christophe Leroy]

Save non volatile registers, XER, CTR, MSR and NIP in exception prolog.

Also assign proper value to r2 and r3 there.

For now, recalculate thread pointer in prepare_transfer_to_handler.
It will disappear once KUAP is ported to C.

And remove the comment which is now completely wrong.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
 arch/powerpc/kernel/entry_32.S   | 27 ++++-----------------------
 arch/powerpc/kernel/head_32.h    | 12 ++++++++++++
 arch/powerpc/kernel/head_booke.h | 12 ++++++++++++
 3 files changed, 28 insertions(+), 23 deletions(-)

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index bcf8452ebb58..46b3854e7318 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -48,29 +48,11 @@
  */
 	.align	12
 
-/*
- * This code finishes saving the registers to the exception frame
- * and jumps to the appropriate handler for the exception, turning
- * on address translation.
- * Note that we rely on the caller having set cr0.eq iff the exception
- * occurred in kernel mode (i.e. MSR:PR = 0).
- */
 	.globl	prepare_transfer_to_handler
 prepare_transfer_to_handler:
-	SAVE_NVGPRS(r11)
-	addi	r3,r1,STACK_FRAME_OVERHEAD
-	stw	r2,GPR2(r11)
-	stw	r12,_NIP(r11)
-	stw	r9,_MSR(r11)
-	andi.	r2,r9,MSR_PR
-	mfctr	r12
-	mfspr	r2,SPRN_XER
-	stw	r12,_CTR(r11)
-	stw	r2,_XER(r11)
-	mfspr	r12,SPRN_SPRG_THREAD
-	tovirt(r12, r12)
+	andi.	r12,r9,MSR_PR
+	addi	r12,r2,THREAD
 	beq	2f
-	addi	r2, r12, -THREAD
 #ifdef CONFIG_PPC_BOOK3S_32
 	kuep_lock r11, r12
 #endif
@@ -78,8 +60,7 @@ prepare_transfer_to_handler:
 
 	/* if from kernel, check interrupted DOZE/NAP mode */
 2:
-	kuap_save_and_lock r11, r12, r9, r2, r6
-	addi	r2, r12, -THREAD
+	kuap_save_and_lock r11, r12, r9, r5, r6
 #if defined(CONFIG_PPC_BOOK3S_32) || defined(CONFIG_E500)
 	lwz	r12,TI_LOCAL_FLAGS(r2)
 	mtcrf	0x01,r12
@@ -293,7 +274,7 @@ fast_exception_return:
 
 2:	REST_4GPRS(3, r11)
 	lwz	r10,_CCR(r11)
-	REST_GPR(1, r11)
+	REST_2GPRS(1, r11)
 	mtcr	r10
 	lwz	r10,_LINK(r11)
 	mtlr	r10
diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
index ba20bfabdf63..80e45c800496 100644
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h
@@ -117,6 +117,18 @@ _ASM_NOKPROBE_SYMBOL(\name\()_virt)
 	stw	r10,_TRAP(r1)
 	SAVE_4GPRS(3, r1)
 	SAVE_2GPRS(7, r1)
+	SAVE_NVGPRS(r1)
+	stw	r2,GPR2(r1)
+	stw	r12,_NIP(r1)
+	stw	r9,_MSR(r1)
+	mfctr	r10
+	mfspr	r2,SPRN_SPRG_THREAD
+	stw	r10,_CTR(r1)
+	tovirt(r2, r2)
+	mfspr	r10,SPRN_XER
+	addi	r2, r2, -THREAD
+	stw	r10,_XER(r1)
+	addi	r3,r1,STACK_FRAME_OVERHEAD
 .endm
 
 .macro prepare_transfer_to_handler
diff --git a/arch/powerpc/kernel/head_booke.h b/arch/powerpc/kernel/head_booke.h
index 4d583fbef0b6..7f3dd5fae51d 100644
--- a/arch/powerpc/kernel/head_booke.h
+++ b/arch/powerpc/kernel/head_booke.h
@@ -89,6 +89,18 @@ END_BTB_FLUSH_SECTION
 	stw	r10,_TRAP(r1)
 	SAVE_4GPRS(3, r1)
 	SAVE_2GPRS(7, r1)
+	SAVE_NVGPRS(r1)
+	stw	r2,GPR2(r1)
+	stw	r12,_NIP(r1)
+	stw	r9,_MSR(r1)
+	mfctr	r10
+	mfspr	r2,SPRN_SPRG_THREAD
+	stw	r10,_CTR(r1)
+	tovirt(r2, r2)
+	mfspr	r10,SPRN_XER
+	addi	r2, r2, -THREAD
+	stw	r10,_XER(r1)
+	addi	r3,r1,STACK_FRAME_OVERHEAD
 .endm
 
 .macro prepare_transfer_to_handler
-- 
2.25.0