Subject: [PATCH] powerpc64/idle: Fix SP offsets when saving GPRs

From: "Christopher M. Riedl" <[email-masked]>
Date: Fri, 29 Jan 2021 21:04:30 -0600

The idle entry/exit code saves/restores GPRs in the stack "red zone"
(Protected Zone according to PowerPC64 ELF ABI v2). However, the offset
used for the first GPR is incorrect and overwrites the back chain - the
Protected Zone actually starts below the current SP. In practice this is
probably not an issue, but it's still incorrect so fix it.

Signed-off-by: Christopher M. Riedl <[email-masked]>
---
 arch/powerpc/kernel/idle_book3s.S | 126 +++++++++++++++---------------
 1 file changed, 63 insertions(+), 63 deletions(-)

diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S
index 22f249b6f58d..80cf35183e9d 100644
--- a/arch/powerpc/kernel/idle_book3s.S
+++ b/arch/powerpc/kernel/idle_book3s.S
@@ -53,27 +53,27 @@ _GLOBAL(isa300_idle_stop_mayloss)
 	mflr	r4
 	mfcr	r5
 	/* use stack red zone rather than a new frame for saving regs */
-	std	r2,-8*0(r1)
-	std	r14,-8*1(r1)
-	std	r15,-8*2(r1)
-	std	r16,-8*3(r1)
-	std	r17,-8*4(r1)
-	std	r18,-8*5(r1)
-	std	r19,-8*6(r1)
-	std	r20,-8*7(r1)
-	std	r21,-8*8(r1)
-	std	r22,-8*9(r1)
-	std	r23,-8*10(r1)
-	std	r24,-8*11(r1)
-	std	r25,-8*12(r1)
-	std	r26,-8*13(r1)
-	std	r27,-8*14(r1)
-	std	r28,-8*15(r1)
-	std	r29,-8*16(r1)
-	std	r30,-8*17(r1)
-	std	r31,-8*18(r1)
-	std	r4,-8*19(r1)
-	std	r5,-8*20(r1)
+	std	r2,-8*1(r1)
+	std	r14,-8*2(r1)
+	std	r15,-8*3(r1)
+	std	r16,-8*4(r1)
+	std	r17,-8*5(r1)
+	std	r18,-8*6(r1)
+	std	r19,-8*7(r1)
+	std	r20,-8*8(r1)
+	std	r21,-8*9(r1)
+	std	r22,-8*10(r1)
+	std	r23,-8*11(r1)
+	std	r24,-8*12(r1)
+	std	r25,-8*13(r1)
+	std	r26,-8*14(r1)
+	std	r27,-8*15(r1)
+	std	r28,-8*16(r1)
+	std	r29,-8*17(r1)
+	std	r30,-8*18(r1)
+	std	r31,-8*19(r1)
+	std	r4,-8*20(r1)
+	std	r5,-8*21(r1)
 	/* 168 bytes */
 	PPC_STOP
 	b	.	/* catch bugs */
@@ -89,8 +89,8 @@ _GLOBAL(isa300_idle_stop_mayloss)
  */
 _GLOBAL(idle_return_gpr_loss)
 	ld	r1,PACAR1(r13)
-	ld	r4,-8*19(r1)
-	ld	r5,-8*20(r1)
+	ld	r4,-8*20(r1)
+	ld	r5,-8*21(r1)
 	mtlr	r4
 	mtcr	r5
 	/*
@@ -98,25 +98,25 @@ _GLOBAL(idle_return_gpr_loss)
 	 * from PACATOC. This could be avoided for that less common case
 	 * if KVM saved its r2.
 	 */
-	ld	r2,-8*0(r1)
-	ld	r14,-8*1(r1)
-	ld	r15,-8*2(r1)
-	ld	r16,-8*3(r1)
-	ld	r17,-8*4(r1)
-	ld	r18,-8*5(r1)
-	ld	r19,-8*6(r1)
-	ld	r20,-8*7(r1)
-	ld	r21,-8*8(r1)
-	ld	r22,-8*9(r1)
-	ld	r23,-8*10(r1)
-	ld	r24,-8*11(r1)
-	ld	r25,-8*12(r1)
-	ld	r26,-8*13(r1)
-	ld	r27,-8*14(r1)
-	ld	r28,-8*15(r1)
-	ld	r29,-8*16(r1)
-	ld	r30,-8*17(r1)
-	ld	r31,-8*18(r1)
+	ld	r2,-8*1(r1)
+	ld	r14,-8*2(r1)
+	ld	r15,-8*3(r1)
+	ld	r16,-8*4(r1)
+	ld	r17,-8*5(r1)
+	ld	r18,-8*6(r1)
+	ld	r19,-8*7(r1)
+	ld	r20,-8*8(r1)
+	ld	r21,-8*9(r1)
+	ld	r22,-8*10(r1)
+	ld	r23,-8*11(r1)
+	ld	r24,-8*12(r1)
+	ld	r25,-8*13(r1)
+	ld	r26,-8*14(r1)
+	ld	r27,-8*15(r1)
+	ld	r28,-8*16(r1)
+	ld	r29,-8*17(r1)
+	ld	r30,-8*18(r1)
+	ld	r31,-8*19(r1)
 	blr
 
 /*
@@ -155,27 +155,27 @@ _GLOBAL(isa206_idle_insn_mayloss)
 	mflr	r4
 	mfcr	r5
 	/* use stack red zone rather than a new frame for saving regs */
-	std	r2,-8*0(r1)
-	std	r14,-8*1(r1)
-	std	r15,-8*2(r1)
-	std	r16,-8*3(r1)
-	std	r17,-8*4(r1)
-	std	r18,-8*5(r1)
-	std	r19,-8*6(r1)
-	std	r20,-8*7(r1)
-	std	r21,-8*8(r1)
-	std	r22,-8*9(r1)
-	std	r23,-8*10(r1)
-	std	r24,-8*11(r1)
-	std	r25,-8*12(r1)
-	std	r26,-8*13(r1)
-	std	r27,-8*14(r1)
-	std	r28,-8*15(r1)
-	std	r29,-8*16(r1)
-	std	r30,-8*17(r1)
-	std	r31,-8*18(r1)
-	std	r4,-8*19(r1)
-	std	r5,-8*20(r1)
+	std	r2,-8*1(r1)
+	std	r14,-8*2(r1)
+	std	r15,-8*3(r1)
+	std	r16,-8*4(r1)
+	std	r17,-8*5(r1)
+	std	r18,-8*6(r1)
+	std	r19,-8*7(r1)
+	std	r20,-8*8(r1)
+	std	r21,-8*9(r1)
+	std	r22,-8*10(r1)
+	std	r23,-8*11(r1)
+	std	r24,-8*12(r1)
+	std	r25,-8*13(r1)
+	std	r26,-8*14(r1)
+	std	r27,-8*15(r1)
+	std	r28,-8*16(r1)
+	std	r29,-8*17(r1)
+	std	r30,-8*18(r1)
+	std	r31,-8*19(r1)
+	std	r4,-8*20(r1)
+	std	r5,-8*21(r1)
 	cmpwi	r3,PNV_THREAD_NAP
 	bne	1f
 	IDLE_STATE_ENTER_SEQ_NORET(PPC_NAP)
-- 
2.26.1