powerpc: rough platform support

Author: richo

src/rt/arch/powerpc/morestack.S

@@ -0,0 +1,20 @@
+#include "macros.S"
+
+// Mark stack as non-executable
+#if defined(__linux__) && defined(__ELF__)
+.section       .note.GNU-stack, "", %progbits
+#endif
+
+/* See i386/morestack.S for the lengthy, general explanation. */
+
+.global rust_stack_exhausted
+
+.hidden __morestack
+
+// FIXME(POWERPC): this might not be perfectly right but works for now
+__morestack:
+       .cfi_startproc
+       bl rust_stack_exhausted
+       // the above function ensures that it never returns
+       .cfi_endproc
+.end  __morestack

src/rt/arch/powerpc/record_sp.S

@@ -0,0 +1,4 @@
+// Mark stack as non-executable
+#if defined(__linux__) && defined(__ELF__)
+.section       .note.GNU-stack, "", %progbits
+#endif