syscalls/x86: Wire up COMPAT_SYSCALL_DEFINE0

x86 has special handling for COMPAT_SYSCALL_DEFINEx, but there was
no override for COMPAT_SYSCALL_DEFINE0.  Wire it up so that we can
use it for rt_sigreturn.

Signed-off-by: Andy Lutomirski <[email protected]>
Signed-off-by: Sami Tolvanen <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: H . Peter Anvin <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

Author: amluto

arch/x86/include/asm/syscall_wrapper.h

@@ -28,13 +28,21 @@
  * kernel/sys_ni.c and SYS_NI in kernel/time/posix-stubs.c to cover this
  * case as well.
  */
+#define __IA32_COMPAT_SYS_STUB0(x, name)				\
+	asmlinkage long __ia32_compat_sys_##name(const struct pt_regs *regs);\
+	ALLOW_ERROR_INJECTION(__ia32_compat_sys_##name, ERRNO);		\
+	asmlinkage long __ia32_compat_sys_##name(const struct pt_regs *regs)\
+	{								\
+		return __se_compat_sys_##name();			\
+	}
+
 #define __IA32_COMPAT_SYS_STUBx(x, name, ...)				\
 	asmlinkage long __ia32_compat_sys##name(const struct pt_regs *regs);\
 	ALLOW_ERROR_INJECTION(__ia32_compat_sys##name, ERRNO);		\
 	asmlinkage long __ia32_compat_sys##name(const struct pt_regs *regs)\
 	{								\
 		return __se_compat_sys##name(SC_IA32_REGS_TO_ARGS(x,__VA_ARGS__));\
-	}								\
+	}
 
 #define __IA32_SYS_STUBx(x, name, ...)					\
 	asmlinkage long __ia32_sys##name(const struct pt_regs *regs);	\
@@ -76,15 +84,24 @@
  * of the x86-64-style parameter ordering of x32 syscalls. The syscalls common
  * with x86_64 obviously do not need such care.
  */
+#define __X32_COMPAT_SYS_STUB0(x, name, ...)				\
+	asmlinkage long __x32_compat_sys_##name(const struct pt_regs *regs);\
+	ALLOW_ERROR_INJECTION(__x32_compat_sys_##name, ERRNO);		\
+	asmlinkage long __x32_compat_sys_##name(const struct pt_regs *regs)\
+	{								\
+		return __se_compat_sys_##name();\
+	}
+
 #define __X32_COMPAT_SYS_STUBx(x, name, ...)				\
 	asmlinkage long __x32_compat_sys##name(const struct pt_regs *regs);\
 	ALLOW_ERROR_INJECTION(__x32_compat_sys##name, ERRNO);		\
 	asmlinkage long __x32_compat_sys##name(const struct pt_regs *regs)\
 	{								\
 		return __se_compat_sys##name(SC_X86_64_REGS_TO_ARGS(x,__VA_ARGS__));\
-	}								\
+	}
 
 #else /* CONFIG_X86_X32 */
+#define __X32_COMPAT_SYS_STUB0(x, name)
 #define __X32_COMPAT_SYS_STUBx(x, name, ...)
 #endif /* CONFIG_X86_X32 */
 
@@ -95,6 +112,17 @@
  * mapping of registers to parameters, we need to generate stubs for each
  * of them.
  */
+#define COMPAT_SYSCALL_DEFINE0(name)					\
+	static long __se_compat_sys_##name(void);			\
+	static inline long __do_compat_sys_##name(void);		\
+	__IA32_COMPAT_SYS_STUB0(x, name)				\
+	__X32_COMPAT_SYS_STUB0(x, name)					\
+	static long __se_compat_sys_##name(void)			\
+	{								\
+		return __do_compat_sys_##name();			\
+	}								\
+	static inline long __do_compat_sys_##name(void)
+
 #define COMPAT_SYSCALL_DEFINEx(x, name, ...)					\
 	static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__));	\
 	static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\