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@vger.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/c65e105b63aaf74f91a14f845bc77192350b84a6.1612796617.git.christophe.leroy@csgroup.eu

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index b102b40c4988b94022634242a937f84e65ec1b8a..b1e36602c013d01b5335e2c21fc3d37c3de7cdbe 100644 (file)
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -351,6 +351,9 @@ 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