kill signal_pt_regs()

Once upon at it was used on hot paths, but that had not been
true since 2013.  IOW, there's no point for arch-optimized
equivalent of task_pt_regs(current) - remaining two users are
not worth bothering with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/alpha/include/asm/ptrace.h

@@ -16,7 +16,6 @@
 
 #define current_pt_regs() \
   ((struct pt_regs *) ((char *)current_thread_info() + 2*PAGE_SIZE) - 1)
-#define signal_pt_regs current_pt_regs
 
 #define force_successful_syscall_return() (current_pt_regs()->r0 = 0)
 

fs/coredump.c

@@ -525,7 +525,7 @@ void do_coredump(const kernel_siginfo_t *siginfo)
 	static atomic_t core_dump_count = ATOMIC_INIT(0);
 	struct coredump_params cprm = {
 		.siginfo = siginfo,
-		.regs = signal_pt_regs(),
+		.regs = task_pt_regs(current),
 		.limit = rlimit(RLIMIT_CORE),
 		/*
 		 * We must use the same mm->flags while dumping core to avoid

include/linux/ptrace.h

@@ -389,15 +389,6 @@ static inline void user_single_step_report(struct pt_regs *regs)
 #define current_pt_regs() task_pt_regs(current)
 #endif
 
-/*
- * unlike current_pt_regs(), this one is equal to task_pt_regs(current)
- * on *all* architectures; the only reason to have a per-arch definition
- * is optimisation.
- */
-#ifndef signal_pt_regs
-#define signal_pt_regs() task_pt_regs(current)
-#endif
-
 #ifndef current_user_stack_pointer
 #define current_user_stack_pointer() user_stack_pointer(current_pt_regs())
 #endif

kernel/signal.c

@@ -1255,7 +1255,7 @@ int send_signal_locked(int sig, struct kernel_siginfo *info,
 
 static void print_fatal_signal(int signr)
 {
-	struct pt_regs *regs = signal_pt_regs();
+	struct pt_regs *regs = task_pt_regs(current);
 	pr_info("potentially unexpected fatal signal %d.\n", signr);
 
 #if defined(__i386__) && !defined(__arch_um__)