x86/syscall: Move sys_ni_syscall()

Move sys_ni_syscall() to kernel/process.c, and remove the now empty
entry/common.c

No functional changes.

Signed-off-by: Brian Gerst <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Reviewed-by: Sohil Mehta <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: Brian Gerst

arch/x86/entry/Makefile

@@ -7,16 +7,13 @@ KASAN_SANITIZE := n
 UBSAN_SANITIZE := n
 KCOV_INSTRUMENT := n
 
-CFLAGS_REMOVE_common.o		= $(CC_FLAGS_FTRACE)
 CFLAGS_REMOVE_syscall_32.o	= $(CC_FLAGS_FTRACE)
 CFLAGS_REMOVE_syscall_64.o	= $(CC_FLAGS_FTRACE)
 
-CFLAGS_common.o			+= -fno-stack-protector
 CFLAGS_syscall_32.o		+= -fno-stack-protector
 CFLAGS_syscall_64.o		+= -fno-stack-protector
 
 obj-y				:= entry.o entry_$(BITS).o syscall_$(BITS).o
-obj-y				+= common.o
 
 obj-y				+= vdso/
 obj-y				+= vsyscall/

arch/x86/entry/common.c

@@ -1063,3 +1063,8 @@ SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2)
 
 	return -EINVAL;
 }
+
+SYSCALL_DEFINE0(ni_syscall)
+{
+	return -ENOSYS;
+}