Introduce a WEAK_REFERENCE() alias and use it. Get rid of the CNAME and the

CONCAT macros in SYS.h.

Reviewed by:	bde, kib

lib/libc/amd64/SYS.h

@@ -36,20 +36,17 @@
 #include <sys/syscall.h>
 #include <machine/asm.h>
 
-#define	RSYSCALL(x)	ENTRY(__CONCAT(__sys_,x));			\
-			.weak CNAME(x);					\
-			.set CNAME(x),CNAME(__CONCAT(__sys_,x));	\
-			.weak CNAME(__CONCAT(_,x));			\
-			.set CNAME(__CONCAT(_,x)),CNAME(__CONCAT(__sys_,x)); \
-			mov __CONCAT($SYS_,x),%eax; KERNCALL;		\
+#define	RSYSCALL(name)	ENTRY(__sys_##name);				\
+			WEAK_REFERENCE(__sys_##name, name);		\
+			WEAK_REFERENCE(__sys_##name, _##name);		\
+			mov $SYS_##name,%eax; KERNCALL;			\
 			jb HIDENAME(cerror); ret;			\
-			END(__CONCAT(__sys_,x))
+			END(__sys_##name)
 
-#define	PSEUDO(x)	ENTRY(__CONCAT(__sys_,x));			\
-			.weak CNAME(__CONCAT(_,x));			\
-			.set CNAME(__CONCAT(_,x)),CNAME(__CONCAT(__sys_,x)); \
-			mov __CONCAT($SYS_,x),%eax; KERNCALL;		\
+#define	PSEUDO(name)	ENTRY(__sys_##name);				\
+			WEAK_REFERENCE(__sys_##name, _##name);		\
+			mov $SYS_##name,%eax; KERNCALL;			\
 			jb HIDENAME(cerror); ret;			\
-			END(__CONCAT(__sys_,x))
+			END(__sys_##name)
 
-#define KERNCALL	movq %rcx, %r10; syscall
+#define	KERNCALL	movq %rcx, %r10; syscall

lib/libc/amd64/gen/_setjmp.S

@@ -63,8 +63,7 @@ ENTRY(_setjmp)
 	ret
 END(_setjmp)
 
-	.weak	CNAME(_longjmp)
-	.set	CNAME(_longjmp),CNAME(___longjmp)
+	WEAK_REFERENCE(___longjmp, _longjmp)
 ENTRY(___longjmp)
 	movq	%rdi,%rdx
 	/* Restore the mxcsr, but leave exception flags intact. */

lib/libc/amd64/gen/setjmp.S

@@ -73,8 +73,7 @@ ENTRY(setjmp)
 	ret
 END(setjmp)
 
-	.weak CNAME(longjmp)
-	.set CNAME(longjmp),CNAME(__longjmp)
+	WEAK_REFERENCE(__longjmp, longjmp)
 ENTRY(__longjmp)
 	pushq	%rdi
 	pushq	%rsi

lib/libc/amd64/gen/sigsetjmp.S

@@ -80,8 +80,7 @@ ENTRY(sigsetjmp)
 	ret
 END(sigsetjmp)
 
-	.weak CNAME(siglongjmp)
-	.set CNAME(siglongjmp),CNAME(__siglongjmp)
+	WEAK_REFERENCE(__siglongjmp, siglongjmp)
 ENTRY(__siglongjmp)
 	cmpl	$0,88(%rdi)
 	jz	2f

lib/libc/amd64/sys/getcontext.S

@@ -34,10 +34,8 @@ __FBSDID("$FreeBSD$");
  * Otherwise, the setcontext() syscall will return here and we'll
  * pop off the return address and go to the *setcontext* call.
  */
-	.weak	_getcontext
-	.set	_getcontext,__sys_getcontext
-	.weak	getcontext
-	.set	getcontext,__sys_getcontext
+	WEAK_REFERENCE(__sys_getcontext, _getcontext)
+	WEAK_REFERENCE(__sys_getcontext, getcontext)
 ENTRY(__sys_getcontext)
 	movq	(%rsp),%rsi	/* save getcontext return address */
 	mov	$SYS_getcontext,%rax

lib/libc/amd64/sys/pipe.S

@@ -38,10 +38,8 @@ __FBSDID("$FreeBSD$");
 
 #include "SYS.h"
 
-	.weak	_pipe
-	.set	_pipe,__sys_pipe
-	.weak	pipe
-	.set	pipe,__sys_pipe
+	WEAK_REFERENCE(__sys_pipe, _pipe)
+	WEAK_REFERENCE(__sys_pipe, pipe)
 ENTRY(__sys_pipe)
 	mov	$SYS_pipe,%rax
 	KERNCALL

lib/libc/amd64/sys/reboot.S

@@ -38,10 +38,8 @@ __FBSDID("$FreeBSD$");
 
 #include "SYS.h"
 
-	.weak	_reboot
-	.set	_reboot,__sys_reboot
-	.weak	reboot
-	.set	reboot,__sys_reboot
+	WEAK_REFERENCE(__sys_reboot, _reboot)
+	WEAK_REFERENCE(__sys_reboot, reboot)
 ENTRY(__sys_reboot)
 	mov	$SYS_reboot,%rax
 	KERNCALL

lib/libc/amd64/sys/setlogin.S

@@ -40,10 +40,8 @@ __FBSDID("$FreeBSD$");
 
 .globl	CNAME(_logname_valid)		/* in _getlogin() */
 
-	.weak	_setlogin
-	.set	_setlogin,__sys_setlogin
-	.weak	setlogin
-	.set	setlogin,__sys_setlogin
+	WEAK_REFERENCE(__sys_setlogin, _setlogin)
+	WEAK_REFERENCE(__sys_setlogin, setlogin)
 ENTRY(__sys_setlogin)
 	mov	$SYS_setlogin,%rax
 	KERNCALL

lib/libc/amd64/sys/vfork.S

@@ -38,10 +38,8 @@ __FBSDID("$FreeBSD$");
 
 #include "SYS.h"
 
-	.weak	_vfork
-	.set	_vfork,__sys_vfork
-	.weak	vfork
-	.set	vfork,__sys_vfork
+	WEAK_REFERENCE(__sys_vfork, _vfork)
+	WEAK_REFERENCE(__sys_vfork, vfork)
 ENTRY(__sys_vfork)
 	popq	%rsi		/* fetch return address (%rsi preserved) */
 	mov	$SYS_vfork,%rax

sys/amd64/include/asm.h

@@ -77,6 +77,15 @@
 #endif
 
 #define	END(x)		.size x, . - x
+/*
+ * WEAK_REFERENCE(): create a weak reference alias from sym. 
+ * The macro is not a general asm macro that takes arbitrary names,
+ * but one that takes only C names. It does the non-null name
+ * translation inside the macro.
+ */
+#define	WEAK_REFERENCE(sym, alias)					\
+	.weak CNAME(alias);						\
+	.equ CNAME(alias),CNAME(sym)
 
 #define RCSID(x)	.text; .asciz x