From 8dc1a9d9e9856ec8583aa726f035182056c44bf3 Mon Sep 17 00:00:00 2001
From: Nicholas Piggin <npiggin@gmail.com>
Date: Wed, 10 Jan 2018 03:07:15 +1100
Subject: [PATCH 02/10] powerpc/64: Add macros for annotating the destination
 of rfid/hrfid

References: bsc#1068032
Patch-mainline: v4.15-rc8
Git-commit: 50e51c13b3822d14ff6df4279423e4b7b2269bc3

The rfid/hrfid ((Hypervisor) Return From Interrupt) instruction is
used for switching from the kernel to userspace, and from the
hypervisor to the guest kernel. However it can and is also used for
other transitions, eg. from real mode kernel code to virtual mode
kernel code, and it's not always clear from the code what the
destination context is.

To make it clearer when reading the code, add macros which encode the
expected destination context.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/include/asm/exception-64e.h |  6 ++++++
 arch/powerpc/include/asm/exception-64s.h | 29 +++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/arch/powerpc/include/asm/exception-64e.h b/arch/powerpc/include/asm/exception-64e.h
index a703452d67b6..555e22d5e07f 100644
--- a/arch/powerpc/include/asm/exception-64e.h
+++ b/arch/powerpc/include/asm/exception-64e.h
@@ -209,5 +209,11 @@ exc_##label##_book3e:
 	ori	r3,r3,vector_offset@l;		\
 	mtspr	SPRN_IVOR##vector_number,r3;
 
+#define RFI_TO_KERNEL							\
+	rfi
+
+#define RFI_TO_USER							\
+	rfi
+
 #endif /* _ASM_POWERPC_EXCEPTION_64E_H */
 
diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index 33473cbc0986..06176c1f95d9 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -51,6 +51,35 @@
 
 #define EX_SIZE		13	/* size in u64 units */
 
+/* Macros for annotating the expected destination of (h)rfid */
+
+#define RFI_TO_KERNEL							\
+	rfid
+
+#define RFI_TO_USER							\
+	rfid
+
+#define RFI_TO_USER_OR_KERNEL						\
+	rfid
+
+#define RFI_TO_GUEST							\
+	rfid
+
+#define HRFI_TO_KERNEL							\
+	hrfid
+
+#define HRFI_TO_USER							\
+	hrfid
+
+#define HRFI_TO_USER_OR_KERNEL						\
+	hrfid
+
+#define HRFI_TO_GUEST							\
+	hrfid
+
+#define HRFI_TO_UNKNOWN							\
+	hrfid
+
 #ifdef CONFIG_RELOCATABLE
 #define __EXCEPTION_RELON_PROLOG_PSERIES_1(label, h)			\
 	mfspr	r11,SPRN_##h##SRR0;	/* save SRR0 */			\
-- 
2.13.6