[PATCH 13/14] powerpc/rtas: enture rtas_call is called with MMU enabled

[Nicholas Piggin <npiggin@gmail.com>]

rtas_call must not be called with the MMU disabled because in case
of rtas error, log_error is called which requires MMU enabled. Add
a test and warning for this.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/kernel/rtas.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 1fc22138e3ab..adf4892aeecd 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -479,6 +479,11 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...)
 	if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE)
 		return -1;
 
+	if ((mfmsr() & (MSR_IR|MSR_DR)) != (MSR_IR|MSR_DR)) {
+		WARN_ON_ONCE(1);
+		return -1;
+	}
+
 	s = lock_rtas();
 
 	/* We use the global rtas args buffer */
-- 
2.23.0