consolidate cond_syscall and SYSCALL_ALIAS declarations

take them to asm/linkage.h, with default in linux/linkage.h

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

include/linux/linkage.h

@@ -2,6 +2,7 @@
 #define _LINUX_LINKAGE_H
 
 #include <linux/compiler.h>
+#include <linux/stringify.h>
 #include <asm/linkage.h>
 
 #ifdef __cplusplus
@@ -14,6 +15,26 @@
 #define asmlinkage CPP_ASMLINKAGE
 #endif
 
+#ifndef SYMBOL_NAME
+#ifdef CONFIG_SYMBOL_PREFIX
+#define SYMBOL_NAME(x) CONFIG_SYMBOL_PREFIX ## x
+#else
+#define SYMBOL_NAME(x) x
+#endif
+#endif
+#define __SYMBOL_NAME(x) __stringify(SYMBOL_NAME(x))
+
+#ifndef cond_syscall
+#define cond_syscall(x) asm(".weak\t" __SYMBOL_NAME(x) \
+	"\n\t.set\t" __SYMBOL_NAME(x) "," __SYMBOL_NAME(sys_ni_syscall));
+#endif
+
+#ifndef SYSCALL_ALIAS
+#define SYSCALL_ALIAS(alias, name)				\
+	asm ("\t.globl " __SYMBOL_NAME(alias)			\
+	"\n\t.set\t" __SYMBOL_NAME(alias) "," __SYMBOL_NAME(name))
+#endif
+
 #define __page_aligned_data	__section(.data..page_aligned) __aligned(PAGE_SIZE)
 #define __page_aligned_bss	__section(.bss..page_aligned) __aligned(PAGE_SIZE)