linux-kernel - [PATCH] powerpc/32s: Fix RTAS machine check with VMAP stack

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Date:   Tue, 22 Dec 2020 07:11:18 +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>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH] powerpc/32s: Fix RTAS machine check with VMAP stack

When we have VMAP stack, exception prolog 1 sets r1, not r11.

Fixes: da7bb43ab9da ("powerpc/32: Fix vmap stack - Properly set r1 before activating MMU")
Fixes: d2e006036082 ("powerpc/32: Use SPRN_SPRG_SCRATCH2 in exception prologs")
Cc: stable@...r.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/kernel/head_book3s_32.S | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S
index 349bf3f0c3af..fbc48a500846 100644
--- a/arch/powerpc/kernel/head_book3s_32.S
+++ b/arch/powerpc/kernel/head_book3s_32.S
@@ -260,9 +260,16 @@ __secondary_hold_acknowledge:
 MachineCheck:
 	EXCEPTION_PROLOG_0
 #ifdef CONFIG_PPC_CHRP
+#ifdef CONFIG_VMAP_STACK
+	mtspr	SPRN_SPRG_SCRATCH2,r1
+	mfspr	r1, SPRN_SPRG_THREAD
+	lwz	r1, RTAS_SP(r1)
+	cmpwi	cr1, r1, 0
+#else
 	mfspr	r11, SPRN_SPRG_THREAD
 	lwz	r11, RTAS_SP(r11)
 	cmpwi	cr1, r11, 0
+#endif
 	bne	cr1, 7f
 #endif /* CONFIG_PPC_CHRP */
 	EXCEPTION_PROLOG_1 for_rtas=1
-- 
2.25.0