provide arch-generic fdpic self-relocation code for crt1 to use

this file is intended to be included by crt_arch.h on fdpic-based
targets and needs to be called from the entry point asm.

diff --git a/src/internal/fdpic_crt.h b/src/internal/fdpic_crt.h
new file mode 100644 (file)
index 0000000..7eb50c6
--- /dev/null
+++ b/src/internal/fdpic_crt.h
@@ -0,0 +1,28 @@
+#include <stdint.h>
+
+__attribute__((__visibility__("hidden")))
+void *__fdpic_fixup(void *map, uintptr_t *a, uintptr_t *z)
+{
+       /* If map is a null pointer, the program was loaded by a
+        * non-FDPIC-aware ELF loader, and fixups are not needed,
+        * but the value for the GOT pointer is. */
+       if (!map) return (void *)z[-1];
+
+       struct {
+               unsigned short version, nsegs;
+               struct fdpic_loadseg {
+                       uintptr_t addr, p_vaddr, p_memsz;
+               } segs[];
+       } *lm = map;
+       int nsegs = lm->nsegs, rseg = 0, vseg = 0;
+       for (;;) {
+               while (*a-lm->segs[rseg].p_vaddr >= lm->segs[rseg].p_memsz)
+                       if (++rseg == nsegs) rseg = 0;
+               uintptr_t *r = (uintptr_t *)
+                       (*a + lm->segs[rseg].addr - lm->segs[rseg].p_vaddr);
+               if (++a == z) return r;
+               while (*r-lm->segs[vseg].p_vaddr >= lm->segs[vseg].p_memsz)
+                       if (++vseg == nsegs) vseg = 0;
+               *r += lm->segs[vseg].addr - lm->segs[vseg].p_vaddr;
+       }
+}