powerpc: Don't add __powerpc_ prefix to syscall entry points

When using syscall wrappers the __SYSCALL_DEFINEx() and related macros
add a "__powerpc_" prefix to all syscall entry points.

So for example sys_mmap becomes __powerpc_sys_mmap.

This risks breaking workflows and tools that expect the old naming
scheme. At a minimum setting a breakpoint on eg. sys_mmap with gdb no
longer works.

There seems to be no compelling reason to add the "__powerpc_" prefix,
other than that it follows what some other arches do (x86, arm64, s390).

But unlike other arches powerpc doesn't always enable syscall wrappers,
so the syscall entry points can change name depending on CONFIG options.

For those reasons drop the "__powerpc_" prefix, reverting to the
existing naming.

Doing so reveals two prototypes in signal.h that have the incorrect type
when syscall wrappers are enabled. There are already prototypes for both
functions in syscalls.h, so drop the ones from signal.h.

Fixes: 7e92e01 ("powerpc: Provide syscall wrapper")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221006135940.1223988-1-mpe@ellerman.id.au

arch/powerpc/include/asm/syscall_wrapper.h

@@ -16,11 +16,11 @@ struct pt_regs;
 	      ,,regs->gpr[6],,regs->gpr[7],,regs->gpr[8])
 
 #define __SYSCALL_DEFINEx(x, name, ...)						\
-	long __powerpc_sys##name(const struct pt_regs *regs);			\
-	ALLOW_ERROR_INJECTION(__powerpc_sys##name, ERRNO);			\
+	long sys##name(const struct pt_regs *regs);			\
+	ALLOW_ERROR_INJECTION(sys##name, ERRNO);			\
 	static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__));		\
 	static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));	\
-	long __powerpc_sys##name(const struct pt_regs *regs)			\
+	long sys##name(const struct pt_regs *regs)			\
 	{									\
 		return __se_sys##name(SC_POWERPC_REGS_TO_ARGS(x,__VA_ARGS__));	\
 	}									\
@@ -35,17 +35,15 @@ struct pt_regs;
 
 #define SYSCALL_DEFINE0(sname)							\
 	SYSCALL_METADATA(_##sname, 0);						\
-	long __powerpc_sys_##sname(const struct pt_regs *__unused);		\
-	ALLOW_ERROR_INJECTION(__powerpc_sys_##sname, ERRNO);			\
-	long __powerpc_sys_##sname(const struct pt_regs *__unused)
+	long sys_##sname(const struct pt_regs *__unused);		\
+	ALLOW_ERROR_INJECTION(sys_##sname, ERRNO);			\
+	long sys_##sname(const struct pt_regs *__unused)
 
 #define COND_SYSCALL(name)							\
-	long __powerpc_sys_##name(const struct pt_regs *regs);			\
-	long __weak __powerpc_sys_##name(const struct pt_regs *regs)		\
+	long sys_##name(const struct pt_regs *regs);			\
+	long __weak sys_##name(const struct pt_regs *regs)		\
 	{									\
 		return sys_ni_syscall();					\
 	}
 
-#define SYS_NI(name) SYSCALL_ALIAS(__powerpc_sys_##name, sys_ni_posix_timers);
-
 #endif // __ASM_POWERPC_SYSCALL_WRAPPER_H

arch/powerpc/include/asm/syscalls.h

@@ -124,7 +124,7 @@ long sys_ppc_fadvise64_64(int fd, int advice,
 
 #define __SYSCALL_WITH_COMPAT(nr, native, compat)	__SYSCALL(nr, native)
 #define __SYSCALL(nr, entry) \
-	long __powerpc_##entry(const struct pt_regs *regs);
+	long entry(const struct pt_regs *regs);
 
 #ifdef CONFIG_PPC64
 #include <asm/syscall_table_64.h>

arch/powerpc/kernel/signal.h

@@ -196,9 +196,6 @@ extern int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
 
 #else /* CONFIG_PPC64 */
 
-extern long sys_rt_sigreturn(void);
-extern long sys_sigreturn(void);
-
 static inline int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
 				     struct task_struct *tsk)
 {

arch/powerpc/kernel/systbl.c

@@ -20,8 +20,7 @@
 
 #undef __SYSCALL
 #ifdef CONFIG_ARCH_HAS_SYSCALL_WRAPPER
-#define __SYSCALL(nr, entry) [nr] = __powerpc_##entry,
-#define __powerpc_sys_ni_syscall	sys_ni_syscall
+#define __SYSCALL(nr, entry) [nr] = entry,
 #else
 /*
  * Coerce syscall handlers with arbitrary parameters to common type