powerpc/64: Add macros for annotating the destination of rfid/hrfid

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>

diff --git a/arch/powerpc/include/asm/exception-64e.h b/arch/powerpc/include/asm/exception-64e.h
index a703452d67b62f63b455098e88988fcc0b3776c6..555e22d5e07f9e21c322af718df72bdf2da0dfa4 100644 (file)
--- 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 b27205297e1d9ca5ca46db9e7189bf9187385803..1af427a3c74f4da63afd9736bd90177b9d266991 100644 (file)
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -74,6 +74,35 @@
  */
 #define EX_R3          EX_DAR
 
+/* 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 */                 \