rtld.c weirdness on powerpc

[Michael Lorenz <macallan%netbsd.org@localhost>]

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Hello,

see here: http://permalink.gmane.org/gmane.os.netbsd.ports.macppc/9602

For some reason we need this patch to get X.org working on macppc:

- --- rtld.c    7 Dec 2007 20:34:05 -0000       1.117
+++ rtld.c      8 Feb 2008 03:04:06 -0000
@@ -801,6 +801,12 @@
        return(NULL);
 }

+static void *
+hackish_return_address(void)
+{
+       return __builtin_return_address(1);
+}
+
 __strong_alias(__dlsym,dlsym)
 void *
 dlsym(void *handle, const char *name)
@@ -820,7 +828,8 @@
        case (intptr_t)RTLD_NEXT:
        case (intptr_t)RTLD_DEFAULT:
        case (intptr_t)RTLD_SELF:
- -             retaddr = __builtin_return_address(0); /* __GNUC__ only */
+               /* retaddr = __builtin_return_address(0);*/ /* __GNUC__ only */
+               retaddr = hackish_return_address();
                if ((obj = _rtld_obj_from_addr(retaddr)) == NULL) {
                        _rtld_error("Cannot determine caller's shared object");
                        return NULL;

Any idea why? The patch doesn't seem to have any ill side effects but  
I'd like to know why it works and why we need it.

have fun
Michael

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