linux-kernel - [PATCH] powerpc: Make set_endian() return EINVAL when not supporting little endian

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Message-Id: <b29c29d205737a833262df38e01c07139f1c3dec.1629899011.git.christophe.leroy@csgroup.eu>
Date:   Wed, 25 Aug 2021 13:43:38 +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: Make set_endian() return EINVAL when not supporting
 little endian

There is no point in modifying MSR_LE bit on CPUs not supporting
little endian.

Just like done for get_endian(), make set_endian() return
EINVAL in that case.

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

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 185beb290580..b2b9919795a2 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1995,6 +1995,10 @@ int set_endian(struct task_struct *tsk, unsigned int val)
 {
 	struct pt_regs *regs = tsk->thread.regs;
 
+	if (!cpu_has_feature(CPU_FTR_PPC_LE) &&
+	    !cpu_has_feature(CPU_FTR_REAL_LE))
+		return -EINVAL;
+
 	if ((val == PR_ENDIAN_LITTLE && !cpu_has_feature(CPU_FTR_REAL_LE)) ||
 	    (val == PR_ENDIAN_PPC_LITTLE && !cpu_has_feature(CPU_FTR_PPC_LE)))
 		return -EINVAL;
-- 
2.25.0