MIPS: Add return errors to protected cache ops

The protected cache ops contain no out of line fixup code to return an
error code in the event of a fault, with the cache op being skipped in
that case. For KVM however we'd like to detect this case as page
faulting will be disabled so it could happen during normal operation if
the GVA page tables were flushed, and need to be handled by the caller.

Add the out-of-line fixup code to load the error value -EFAULT into the
return variable, and adapt the protected cache line functions to pass
the error back to the caller.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org

arch/mips/include/asm/r4kcache.h

@@ -147,49 +147,64 @@ static inline void flush_scache_line(unsigned long addr)
 }
 
 #define protected_cache_op(op,addr)				\
+({								\
+	int __err = 0;						\
 	__asm__ __volatile__(					\
 	"	.set	push			\n"		\
 	"	.set	noreorder		\n"		\
 	"	.set "MIPS_ISA_ARCH_LEVEL"	\n"		\
-	"1:	cache	%0, (%1)		\n"		\
+	"1:	cache	%1, (%2)		\n"		\
 	"2:	.set	pop			\n"		\
+	"	.section .fixup,\"ax\"		\n"		\
+	"3:	li	%0, %3			\n"		\
+	"	j	2b			\n"		\
+	"	.previous			\n"		\
 	"	.section __ex_table,\"a\"	\n"		\
-	"	"STR(PTR)" 1b, 2b		\n"		\
+	"	"STR(PTR)" 1b, 3b		\n"		\
 	"	.previous"					\
-	:							\
-	: "i" (op), "r" (addr))
+	: "+r" (__err)						\
+	: "i" (op), "r" (addr), "i" (-EFAULT));			\
+	__err;							\
+})
+
 
 #define protected_cachee_op(op,addr)				\
+({								\
+	int __err = 0;						\
 	__asm__ __volatile__(					\
 	"	.set	push			\n"		\
 	"	.set	noreorder		\n"		\
 	"	.set	mips0			\n"		\
 	"	.set	eva			\n"		\
-	"1:	cachee	%0, (%1)		\n"		\
+	"1:	cachee	%1, (%2)		\n"		\
 	"2:	.set	pop			\n"		\
+	"	.section .fixup,\"ax\"		\n"		\
+	"3:	li	%0, %3			\n"		\
+	"	j	2b			\n"		\
+	"	.previous			\n"		\
 	"	.section __ex_table,\"a\"	\n"		\
-	"	"STR(PTR)" 1b, 2b		\n"		\
+	"	"STR(PTR)" 1b, 3b		\n"		\
 	"	.previous"					\
-	:							\
-	: "i" (op), "r" (addr))
+	: "+r" (__err)						\
+	: "i" (op), "r" (addr), "i" (-EFAULT));			\
+	__err;							\
+})
 
 /*
  * The next two are for badland addresses like signal trampolines.
  */
-static inline void protected_flush_icache_line(unsigned long addr)
+static inline int protected_flush_icache_line(unsigned long addr)
 {
 	switch (boot_cpu_type()) {
 	case CPU_LOONGSON2:
-		protected_cache_op(Hit_Invalidate_I_Loongson2, addr);
-		break;
+		return protected_cache_op(Hit_Invalidate_I_Loongson2, addr);
 
 	default:
 #ifdef CONFIG_EVA
-		protected_cachee_op(Hit_Invalidate_I, addr);
+		return protected_cachee_op(Hit_Invalidate_I, addr);
 #else
-		protected_cache_op(Hit_Invalidate_I, addr);
+		return protected_cache_op(Hit_Invalidate_I, addr);
 #endif
-		break;
 	}
 }
 
@@ -199,21 +214,21 @@ static inline void protected_flush_icache_line(unsigned long addr)
  * caches.  We're talking about one cacheline unnecessarily getting invalidated
  * here so the penalty isn't overly hard.
  */
-static inline void protected_writeback_dcache_line(unsigned long addr)
+static inline int protected_writeback_dcache_line(unsigned long addr)
 {
 #ifdef CONFIG_EVA
-	protected_cachee_op(Hit_Writeback_Inv_D, addr);
+	return protected_cachee_op(Hit_Writeback_Inv_D, addr);
 #else
-	protected_cache_op(Hit_Writeback_Inv_D, addr);
+	return protected_cache_op(Hit_Writeback_Inv_D, addr);
 #endif
 }
 
-static inline void protected_writeback_scache_line(unsigned long addr)
+static inline int protected_writeback_scache_line(unsigned long addr)
 {
 #ifdef CONFIG_EVA
-	protected_cachee_op(Hit_Writeback_Inv_SD, addr);
+	return protected_cachee_op(Hit_Writeback_Inv_SD, addr);
 #else
-	protected_cache_op(Hit_Writeback_Inv_SD, addr);
+	return protected_cache_op(Hit_Writeback_Inv_SD, addr);
 #endif
 }