kbuild: Include useful absolute symbols in kallsyms

Some absolute symbols are useful, they can even appear in back traces.
Tweak kallsyms to retain the useful absolute symbols.

This list is from ia64, add absolute symbols from other architectures
as required.
Signed-off-by: Keith Owens <kaos@sgi.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

scripts/kallsyms.c

@@ -132,7 +132,17 @@ read_symbol(FILE *in, struct sym_entry *s)
 		_sinittext = s->addr;
 	else if (strcmp(str, "_einittext") == 0)
 		_einittext = s->addr;
-	else if (toupper(s->type) == 'A' || toupper(s->type) == 'U' ||
+	else if (toupper(s->type) == 'A')
+	{
+		/* Keep these useful absolute symbols */
+		if (strcmp(str, "__kernel_syscall_via_break") &&
+		    strcmp(str, "__kernel_syscall_via_epc") &&
+		    strcmp(str, "__kernel_sigtramp") &&
+		    strcmp(str, "__gp"))
+			return -1;
+
+	}
+	else if (toupper(s->type) == 'U' ||
 		 is_arm_mapping_symbol(str))
 		return -1;