vsprintf: add %ps that is the same as %pS but is like %pf

On PowerPC64 function pointers do not point directly at the functions,
but instead point to pointers to the functions. The output of %pF expects
to point to a pointer to the function, whereas %pS will show the function
itself.

mcount returns the direct pointer to the function and not the pointer to
the pointer. Thus %pS must be used to show this. The function tracer
requires printing of the functions without offsets and uses the %pf
instead.

%pF produces run_local_timers+0x4/0x1f
%pf produces just run_local_timers

For PowerPC64, we need to use the direct pointer, and we only have
%pS which will produce .run_local_timers+0x4/0x1f

This patch creates a %ps that matches the %pf as %pS matches %pF.

Cc: Linus Torvalds <[e-mail]>
Cc: Zhao Lei <[e-mail]>
Acked-by: Benjamin Herrenschmidt <[e-mail]>
Signed-off-by: Steven Rostedt <[e-mail]>

lib/vsprintf.c

···
 	unsigned long value = (unsigned long) ptr;
 #ifdef CONFIG_KALLSYMS
 	char sym[KSYM_SYMBOL_LEN];
-	if (ext != 'f')
+	if (ext != 'f' && ext != 's')
 		sprint_symbol(sym, value);
 	else
 		kallsyms_lookup(value, NULL, NULL, NULL, sym);
···
 	case 'F':
 	case 'f':
 		ptr = dereference_function_descriptor(ptr);
+	case 's':
 		/* Fallthrough */
 	case 'S':
 		return symbol_string(buf, end, ptr, spec, *fmt);
···
  * @args: Arguments for the format string
  *
  * This function follows C99 vsnprintf, but has some extensions:
- * %pS output the name of a text symbol
+ * %pS output the name of a text symbol with offset
+ * %ps output the name of a text symbol without offset
  * %pF output the name of a function pointer with its offset
  * %pf output the name of a function pointer without its offset
  * %pR output the address range in a struct resource