The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 98bf2d3f4970179c702ef64db658e0553bc6ef3a Mon Sep 17 00:00:00 2001
From: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Date: Tue, 22 Dec 2020 07:11:18 +0000
Subject: [PATCH] powerpc/32s: Fix RTAS machine check with VMAP stack
When we have VMAP stack, exception prolog 1 sets r1, not r11.
When it is not an RTAS machine check, don't trash r1 because it is
needed by prolog 1.
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@xxxxxxxxxxxxxxx # v5.10+
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
[mpe: Squash in fixup for RTAS machine check from Christophe]
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/bc77d61d1c18940e456a2dee464f1e2eda65a3f0.1608621048.git.christophe.leroy@xxxxxxxxxx
diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S
index 349bf3f0c3af..858fbc8b19f3 100644
--- a/arch/powerpc/kernel/head_book3s_32.S
+++ b/arch/powerpc/kernel/head_book3s_32.S
@@ -260,10 +260,19 @@ __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
+ bne cr1, 7f
+ mfspr r1, SPRN_SPRG_SCRATCH2
+#else
mfspr r11, SPRN_SPRG_THREAD
lwz r11, RTAS_SP(r11)
cmpwi cr1, r11, 0
bne cr1, 7f
+#endif
#endif /* CONFIG_PPC_CHRP */
EXCEPTION_PROLOG_1 for_rtas=1
7: EXCEPTION_PROLOG_2
