linux-kernel - [RFC PATCH v2 09/13] powerpc/syscall: Selectively check MSR_RI and MSR

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Date:   Sun,  5 Apr 2020 17:44:44 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>, npiggin@...il.com,
        msuchanek@...e.de
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [RFC PATCH v2 09/13] powerpc/syscall: Selectively check MSR_RI and
 MSR_PR on syscall entry

In system_call_exception(), MSR_RI needs to also be checked on 8xx.
Only book3e doesn't have MSR_RI.

On PPC32, MSR_PR is checked in real mode to avoid clobbering the
stack, so no need to check and panic in system_call_exception().

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
---
 arch/powerpc/kernel/syscall.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/syscall.c b/arch/powerpc/kernel/syscall.c
index 986489ea9fb4..69d75fc4a5eb 100644
--- a/arch/powerpc/kernel/syscall.c
+++ b/arch/powerpc/kernel/syscall.c
@@ -36,9 +36,9 @@ notrace long system_call_exception(long r3, long r4, long r5,
 
 	trace_hardirqs_off(); /* finish reconciling */
 
-	if (IS_ENABLED(CONFIG_PPC_BOOK3S))
+	if (!IS_ENABLED(CONFIG_PPC_BOOK3E))
 		BUG_ON(!(regs->msr & MSR_RI));
-	BUG_ON(!(regs->msr & MSR_PR));
+	BUG_ON(IS_ENABLED(CONFIG_PPC64) && !(regs->msr & MSR_PR));
 	BUG_ON(!FULL_REGS(regs));
 #ifdef CONFIG_PPC64
 	BUG_ON(regs->softe != IRQS_ENABLED);
-- 
2.25.0