parisc: Fix lpa and lpa_user defines

Commit Message

John David Anglin Dec. 22, 2021, 4:01 p.m. UTC

While working on the rewrite to the light-weight syscall and futex code,
I experimented with using a hash index based on the user physical address
of atomic variable. This exposed two problems with the lpa and lpa_user
defines.

Because of the copy instruction, the pa argument needs to be an early
clobber argument. This prevents gcc from allocating the va and pa
arguments to the same register.

Secondly, the lpa instruction can cause a page fault so we need to
catch exceptions.

Signed-off-by: John David Anglin <[e-mail]>
---

Patch

diff --git a/arch/parisc/include/asm/special_insns.h b/arch/parisc/include/asm/special_insns.h
index a303ae9a77f4..0493cbf70012 100644
--- a/arch/parisc/include/asm/special_insns.h
+++ b/arch/parisc/include/asm/special_insns.h
@@ -2,26 +2,30 @@ 
 #ifndef __PARISC_SPECIAL_INSNS_H
 #define __PARISC_SPECIAL_INSNS_H
 
-#define lpa(va)	({			\
-	unsigned long pa;		\
-	__asm__ __volatile__(		\
-		"copy %%r0,%0\n\t"	\
-		"lpa %%r0(%1),%0"	\
-		: "=r" (pa)		\
-		: "r" (va)		\
-		: "memory"		\
-	);				\
-	pa;				\
+#define lpa(va)	({					\
+	unsigned long pa;				\
+	__asm__ __volatile__(				\
+		"copy %%r0,%0\n"			\
+		"9998:\tlpa %%r0(%1),%0\n"		\
+		"9999:\n"				\
+		ASM_EXCEPTIONTABLE_ENTRY(9998b, 9999b)	\
+		: "=&r" (pa)				\
+		: "r" (va)				\
+		: "memory"				\
+	);						\
+	pa;						\
 })
 
-#define lpa_user(va)	({		\
-	unsigned long pa;		\
-	__asm__ __volatile__(		\
-		"copy %%r0,%0\n\t"	\
-		"lpa %%r0(%%sr3,%1),%0"	\
-		: "=r" (pa)		\
-		: "r" (va)		\
-		: "memory"		\
+#define lpa_user(va)	({				\
+	unsigned long pa;				\
+	__asm__ __volatile__(				\
+		"copy %%r0,%0\n"			\
+		"9998:\tlpa %%r0(%%sr3,%1),%0\n"	\
+		"9999:\n"				\
+		ASM_EXCEPTIONTABLE_ENTRY(9998b, 9999b)	\
+		: "=&r" (pa)				\
+		: "r" (va)				\
+		: "memory"				\
 	);				\
 	pa;				\
 })