src/internal/fdpic_crt.h

   1 #include <stdint.h>
   2 #include <features.h>
   3
   4 hidden void *__fdpic_fixup(void *map, uintptr_t *a, uintptr_t *z)
   5 {
   6         /* If map is a null pointer, the program was loaded by a
   7          * non-FDPIC-aware ELF loader, and fixups are not needed,
   8          * but the value for the GOT pointer is. */
   9         if (!map) return (void *)z[-1];
  10
  11         struct {
  12                 unsigned short version, nsegs;
  13                 struct fdpic_loadseg {
  14                         uintptr_t addr, p_vaddr, p_memsz;
  15                 } segs[];
  16         } *lm = map;
  17         int nsegs = lm->nsegs, rseg = 0, vseg = 0;
  18         for (;;) {
  19                 while (*a-lm->segs[rseg].p_vaddr >= lm->segs[rseg].p_memsz)
  20                         if (++rseg == nsegs) rseg = 0;
  21                 uintptr_t *r = (uintptr_t *)
  22                         (*a + lm->segs[rseg].addr - lm->segs[rseg].p_vaddr);
  23                 if (++a == z) return r;
  24                 while (*r-lm->segs[vseg].p_vaddr >= lm->segs[vseg].p_memsz)
  25                         if (++vseg == nsegs) vseg = 0;
  26                 *r += lm->segs[vseg].addr - lm->segs[vseg].p_vaddr;
  27         }
  28 }