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#include <stdio.h>
#include "elf.h"
__attribute__((visibility("hidden")))
extern struct Elf64_Dyn _DYNAMIC[];
__attribute__((visibility("hidden")))
extern char __executable_start[];
static struct Elf64_Dyn *dyn_gettag(Elf64_Xword tag) {
for (size_t i = 0;; i++) {
if (_DYNAMIC[i].d_tag == tag) return &_DYNAMIC[i];
if (_DYNAMIC[i].d_tag == DT_NULL) return NULL;
}
}
void elf_selfreloc(void) {
// TODO DT_REL, DT_JMPREL
struct Elf64_Dyn *rela_tag = dyn_gettag(DT_RELA);
if (rela_tag) {
/* not checking pointer validity,
* crashing on an invalid elf is fine */
size_t relasz = dyn_gettag(DT_RELASZ)->d_val;
size_t relaent = dyn_gettag(DT_RELAENT)->d_val;
for (size_t o = 0; o < relasz; o += relaent) {
struct Elf64_Rela *r = (void*)__executable_start + rela_tag->d_ptr + o;
uintptr_t *target = (void*)__executable_start + r->r_offset;
switch (ELF64_R_TYPE(r->r_info)) {
case R_X86_64_RELATIVE:
*target = (uintptr_t)&__executable_start + r->r_addend;
break;
default:
_klogf("elf: unsupported relocation type\n");
}
}
}
}
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