linux-kernel - [PATCH] powerpc/32s: Fix napping restore in data storage interrupt (DSI)

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Message-Id: <731694e0885271f6ee9ffc179eb4bcee78313682.1628003562.git.christophe.leroy@csgroup.eu>
Date:   Tue,  3 Aug 2021 15:14:27 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Finn Thain <fthain@...ux-m68k.org>, userm57@...oo.com
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH] powerpc/32s: Fix napping restore in data storage interrupt
 (DSI)

When a DSI (Data Storage Interrupt) is taken while in NAP mode,
r11 doesn't survive the call to power_save_ppc32_restore().

So use r1 instead of r11 as they both contain the virtual stack
pointer at that point.

Reported-by: Finn Thain <fthain@...ux-m68k.org>
Fixes: 4c0104a83fc3 ("powerpc/32: Dismantle EXC_XFER_STD/LITE/TEMPLATE")
Cc: stable@...r.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/kernel/head_book3s_32.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S
index 764edd860ed4..68e5c0a7e99d 100644
--- a/arch/powerpc/kernel/head_book3s_32.S
+++ b/arch/powerpc/kernel/head_book3s_32.S
@@ -300,7 +300,7 @@ ALT_MMU_FTR_SECTION_END_IFSET(MMU_FTR_HPTE_TABLE)
 	EXCEPTION_PROLOG_1
 	EXCEPTION_PROLOG_2 INTERRUPT_DATA_STORAGE DataAccess handle_dar_dsisr=1
 	prepare_transfer_to_handler
-	lwz	r5, _DSISR(r11)
+	lwz	r5, _DSISR(r1)
 	andis.	r0, r5, DSISR_DABRMATCH@h
 	bne-	1f
 	bl	do_page_fault
-- 
2.25.0