x86/entry: Drop asmlinkage from syscalls

asmlinkage is no longer required since the syscall ABI is now fully under
x86 architecture control.  This makes the 32-bit native syscalls a bit more
effecient by passing in regs via EAX instead of on the stack.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200313195144.164260-18-brgerst@gmail.com

arch/x86/entry/syscall_32.c

@@ -8,7 +8,7 @@
 #include <asm/unistd.h>
 #include <asm/syscall.h>
 
-#define __SYSCALL_I386(nr, sym) extern asmlinkage long __ia32_##sym(const struct pt_regs *);
+#define __SYSCALL_I386(nr, sym) extern long __ia32_##sym(const struct pt_regs *);
 
 #include <asm/syscalls_32.h>
 #undef __SYSCALL_I386

arch/x86/entry/syscall_64.c

@@ -11,7 +11,7 @@
 #define __SYSCALL_X32(nr, sym)
 #define __SYSCALL_COMMON(nr, sym) __SYSCALL_64(nr, sym)
 
-#define __SYSCALL_64(nr, sym) extern asmlinkage long __x64_##sym(const struct pt_regs *);
+#define __SYSCALL_64(nr, sym) extern long __x64_##sym(const struct pt_regs *);
 #include <asm/syscalls_64.h>
 #undef __SYSCALL_64
 

arch/x86/entry/syscall_x32.c

@@ -10,8 +10,8 @@
 
 #define __SYSCALL_64(nr, sym)
 
-#define __SYSCALL_X32(nr, sym) extern asmlinkage long __x32_##sym(const struct pt_regs *);
-#define __SYSCALL_COMMON(nr, sym) extern asmlinkage long __x64_##sym(const struct pt_regs *);
+#define __SYSCALL_X32(nr, sym) extern long __x32_##sym(const struct pt_regs *);
+#define __SYSCALL_COMMON(nr, sym) extern long __x64_##sym(const struct pt_regs *);
 #include <asm/syscalls_64.h>
 #undef __SYSCALL_X32
 #undef __SYSCALL_COMMON

arch/x86/include/asm/syscall.h

@@ -16,7 +16,7 @@
 #include <asm/thread_info.h>	/* for TS_COMPAT */
 #include <asm/unistd.h>
 
-typedef asmlinkage long (*sys_call_ptr_t)(const struct pt_regs *);
+typedef long (*sys_call_ptr_t)(const struct pt_regs *);
 extern const sys_call_ptr_t sys_call_table[];
 
 #if defined(CONFIG_X86_32)

arch/x86/include/asm/syscall_wrapper.h

@@ -8,8 +8,8 @@
 
 struct pt_regs;
 
-extern asmlinkage long __x64_sys_ni_syscall(const struct pt_regs *regs);
-extern asmlinkage long __ia32_sys_ni_syscall(const struct pt_regs *regs);
+extern long __x64_sys_ni_syscall(const struct pt_regs *regs);
+extern long __ia32_sys_ni_syscall(const struct pt_regs *regs);
 
 /*
  * Instead of the generic __SYSCALL_DEFINEx() definition, the x86 version takes
@@ -66,22 +66,21 @@ extern asmlinkage long __ia32_sys_ni_syscall(const struct pt_regs *regs);
 	      ,,(unsigned int)regs->di,,(unsigned int)regs->bp)
 
 #define __SYS_STUB0(abi, name)						\
-	asmlinkage long __##abi##_##name(const struct pt_regs *regs);	\
+	long __##abi##_##name(const struct pt_regs *regs);		\
 	ALLOW_ERROR_INJECTION(__##abi##_##name, ERRNO);			\
-	asmlinkage long __##abi##_##name(const struct pt_regs *regs)	\
+	long __##abi##_##name(const struct pt_regs *regs)		\
 		__alias(__do_##name);
 
 #define __SYS_STUBx(abi, name, ...)					\
-	asmlinkage long __##abi##_##name(const struct pt_regs *regs);	\
+	long __##abi##_##name(const struct pt_regs *regs);		\
 	ALLOW_ERROR_INJECTION(__##abi##_##name, ERRNO);			\
-	asmlinkage long __##abi##_##name(const struct pt_regs *regs)	\
+	long __##abi##_##name(const struct pt_regs *regs)		\
 	{								\
 		return __se_##name(__VA_ARGS__);			\
 	}
 
 #define __COND_SYSCALL(abi, name)					\
-	asmlinkage __weak long						\
-	__##abi##_##name(const struct pt_regs *__unused)		\
+	__weak long __##abi##_##name(const struct pt_regs *__unused)	\
 	{								\
 		return sys_ni_syscall();				\
 	}
@@ -192,11 +191,11 @@ extern asmlinkage long __ia32_sys_ni_syscall(const struct pt_regs *regs);
  * of them.
  */
 #define COMPAT_SYSCALL_DEFINE0(name)					\
-	static asmlinkage long						\
+	static long							\
 	__do_compat_sys_##name(const struct pt_regs *__unused);		\
 	__IA32_COMPAT_SYS_STUB0(name)					\
 	__X32_COMPAT_SYS_STUB0(name)					\
-	static asmlinkage long						\
+	static long							\
 	__do_compat_sys_##name(const struct pt_regs *__unused)
 
 #define COMPAT_SYSCALL_DEFINEx(x, name, ...)					\
@@ -248,12 +247,10 @@ extern asmlinkage long __ia32_sys_ni_syscall(const struct pt_regs *regs);
  */
 #define SYSCALL_DEFINE0(sname)						\
 	SYSCALL_METADATA(_##sname, 0);					\
-	static asmlinkage long						\
-	__do_sys_##sname(const struct pt_regs *__unused);		\
+	static long __do_sys_##sname(const struct pt_regs *__unused);	\
 	__X64_SYS_STUB0(sname)						\
 	__IA32_SYS_STUB0(sname)						\
-	static asmlinkage long						\
-	__do_sys_##sname(const struct pt_regs *__unused)
+	static long __do_sys_##sname(const struct pt_regs *__unused)
 
 #define COND_SYSCALL(name)						\
 	__X64_COND_SYSCALL(name)					\
@@ -268,8 +265,8 @@ extern asmlinkage long __ia32_sys_ni_syscall(const struct pt_regs *regs);
  * For VSYSCALLS, we need to declare these three syscalls with the new
  * pt_regs-based calling convention for in-kernel use.
  */
-asmlinkage long __x64_sys_getcpu(const struct pt_regs *regs);
-asmlinkage long __x64_sys_gettimeofday(const struct pt_regs *regs);
-asmlinkage long __x64_sys_time(const struct pt_regs *regs);
+long __x64_sys_getcpu(const struct pt_regs *regs);
+long __x64_sys_gettimeofday(const struct pt_regs *regs);
+long __x64_sys_time(const struct pt_regs *regs);
 
 #endif /* _ASM_X86_SYSCALL_WRAPPER_H */