earlyclobber

earlyclobber

[Frank Cornelis]

Hi,

I think that in the file include/asm-i386/uaccess.h in some macro's the 
ecx register should be marked as an "earlyclobber" operand since it is 
one. Patch follows.

Frank.

--- linux-2.4.17/include/asm-i386/uaccess.h	Sat Dec 22 09:35:17 2001
+++ linux/include/asm-i386/uaccess.h	Sat Dec 22 17:32:14 2001
@@ -151,7 +151,7 @@
 ({							\
 	long __pu_err = -EFAULT;					\
 	__typeof__(*(ptr)) *__pu_addr = (ptr);		\
-	if (access_ok(VERIFY_WRITE,__pu_addr,size))	\
+	if (access_ok(VERIFY_WRITE,__pu_addr,(size)))	\
 		__put_user_size((x),__pu_addr,(size),__pu_err);	\
 	__pu_err;					\
 })							
@@ -337,7 +337,7 @@
 			"	.align 4\n"			\
 			"	.long 0b,2b\n"			\
 			".previous"				\
-			: "=c"(size), "=&S" (__d0), "=&D" (__d1)\
+			: "=&c"(size), "=&S" (__d0), "=&D" (__d1)\
 			: "1"(from), "2"(to), "0"(size/4)	\
 			: "memory");				\
 		break;						\
@@ -356,7 +356,7 @@
 			"	.long 0b,3b\n"			\
 			"	.long 1b,4b\n"			\
 			".previous"				\
-			: "=c"(size), "=&S" (__d0), "=&D" (__d1)\
+			: "=&c"(size), "=&S" (__d0), "=&D" (__d1)\
 			: "1"(from), "2"(to), "0"(size/4)	\
 			: "memory");				\
 		break;						\
@@ -375,7 +375,7 @@
 			"	.long 0b,3b\n"			\
 			"	.long 1b,4b\n"			\
 			".previous"				\
-			: "=c"(size), "=&S" (__d0), "=&D" (__d1)\
+			: "=&c"(size), "=&S" (__d0), "=&D" (__d1)\
 			: "1"(from), "2"(to), "0"(size/4)	\
 			: "memory");				\
 		break;						\
@@ -397,7 +397,7 @@
 			"	.long 1b,5b\n"			\
 			"	.long 2b,6b\n"			\
 			".previous"				\
-			: "=c"(size), "=&S" (__d0), "=&D" (__d1)\
+			: "=&c"(size), "=&S" (__d0), "=&D" (__d1)\
 			: "1"(from), "2"(to), "0"(size/4)	\
 			: "memory");				\
 		break;						\
@@ -427,7 +427,7 @@
 			"	.align 4\n"			\
 			"	.long 0b,2b\n"			\
 			".previous"				\
-			: "=c"(size), "=&S" (__d0), "=&D" (__d1)\
+			: "=&c"(size), "=&S" (__d0), "=&D" (__d1)\
 			: "1"(from), "2"(to), "0"(size/4)	\
 			: "memory");				\
 		break;						\
@@ -459,7 +459,7 @@
 			"	.long 0b,3b\n"			\
 			"	.long 1b,4b\n"			\
 			".previous"				\
-			: "=c"(size), "=&S" (__d0), "=&D" (__d1)\
+			: "=&c"(size), "=&S" (__d0), "=&D" (__d1)\
 			: "1"(from), "2"(to), "0"(size/4)	\
 			: "memory");				\
 		break;						\
@@ -491,7 +491,7 @@
 			"	.long 0b,3b\n"			\
 			"	.long 1b,4b\n"			\
 			".previous"				\
-			: "=c"(size), "=&S" (__d0), "=&D" (__d1)\
+			: "=&c"(size), "=&S" (__d0), "=&D" (__d1)\
 			: "1"(from), "2"(to), "0"(size/4)	\
 			: "memory");				\
 		break;						\
@@ -533,7 +533,7 @@
 			"	.long 1b,5b\n"			\
 			"	.long 2b,6b\n"			\
 			".previous"				\
-			: "=c"(size), "=&S" (__d0), "=&D" (__d1)\
+			: "=&c"(size), "=&S" (__d0), "=&D" (__d1)\
 			: "1"(from), "2"(to), "0"(size/4)	\
 			: "memory");				\
 		break;						\

Re: earlyclobber

[Roman Zippel]

Hi,

Frank Cornelis wrote:

> I think that in the file include/asm-i386/uaccess.h in some macro's the
> ecx register should be marked as an "earlyclobber" operand since it is
> one. Patch follows.
> 
> Frank.
> 
> @@ -337,7 +337,7 @@
>                         "       .align 4\n"                     \
>                         "       .long 0b,2b\n"                  \
>                         ".previous"                             \
> -                       : "=c"(size), "=&S" (__d0), "=&D" (__d1)\
> +                       : "=&c"(size), "=&S" (__d0), "=&D" (__d1)\
>                         : "1"(from), "2"(to), "0"(size/4)       \
>                         : "memory");                            \
>                 break;                                          \

This isn't needed, as there is no input operand to which it could be
assigned to.

bye, Roman

Re: earlyclobber

[Frank Cornelis]

> > I think that in the file include/asm-i386/uaccess.h in some macro's the
> > ecx register should be marked as an "earlyclobber" operand since it is
> > one. Patch follows.
> 
> How did you notice it?

By simply reading through the source code. It's so much more exciting than 
reading a book and it gets me to sleep in no time :)

Frank.