From 314f6c23dd8d417281eb9e8a516dd98036f2e7b3 Mon Sep 17 00:00:00 2001
From: Michael Ellerman <mpe@ellerman.id.au>
Date: Wed, 22 Dec 2021 00:50:59 +1100
Subject: [PATCH] powerpc/64s: Mask NIP before checking against SRR0
References: bsc#1194869
Patch-mainline: v5.17-rc1
Git-commit: 314f6c23dd8d417281eb9e8a516dd98036f2e7b3
When CONFIG_PPC_RFI_SRR_DEBUG=y we check that NIP and SRR0 match when
returning from interrupts. This can trigger falsely if NIP has either of
its two low bits set via sigreturn or ptrace, while SRR0 has its low two
bits masked in hardware.
As a quick fix make sure to mask the low bits before doing the check.
Fixes: 59dc5bfca0cb ("powerpc/64s: avoid reloading (H)SRR registers if they are still valid")
Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Link: https://lore.kernel.org/r/20211221135101.2085547-1-mpe@ellerman.id.au
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
arch/powerpc/kernel/interrupt_64.S | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/powerpc/kernel/interrupt_64.S b/arch/powerpc/kernel/interrupt_64.S
index d3180139e35a..d729c2e7dae0 100644
--- a/arch/powerpc/kernel/interrupt_64.S
+++ b/arch/powerpc/kernel/interrupt_64.S
@@ -30,6 +30,7 @@ COMPAT_SYS_CALL_TABLE:
.ifc \srr,srr
mfspr r11,SPRN_SRR0
ld r12,_NIP(r1)
+ clrrdi r12,r12,2
100: tdne r11,r12
EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
mfspr r11,SPRN_SRR1
@@ -39,6 +40,7 @@ COMPAT_SYS_CALL_TABLE:
.else
mfspr r11,SPRN_HSRR0
ld r12,_NIP(r1)
+ clrrdi r12,r12,2
100: tdne r11,r12
EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
mfspr r11,SPRN_HSRR1
--
2.31.1