linux-kernel - [PATCH 1/2] powerpc/32s: Add missing call to kuep

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Date:   Wed, 20 Jan 2021 07:33:59 +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 1/2] powerpc/32s: Add missing call to kuep_lock on syscall
 entry

Userspace Execution protection and fast syscall entry were implemented
independently from each other and were both merged in kernel 5.2,
leading to syscall entry missing userspace execution protection.

On syscall entry, execution of user space memory must be
locked in the same way as on exception entry.

Fixes: b86fb88855ea ("powerpc/32: implement fast entry for syscalls on non BOOKE")
Cc: stable@...r.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/kernel/entry_32.S | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 1c9b0ccc2172..9bc4e7dd0bee 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -356,6 +356,9 @@ trace_syscall_entry_irq_off:
 
 	.globl	transfer_to_syscall
 transfer_to_syscall:
+#ifdef CONFIG_PPC_BOOK3S_32
+	kuep_lock r11, r12
+#endif
 #ifdef CONFIG_TRACE_IRQFLAGS
 	andi.	r12,r9,MSR_EE
 	beq-	trace_syscall_entry_irq_off
-- 
2.25.0