Rich Felker | f3ddd17 | 2015-04-13 02:56:26 -0400 | [diff] [blame] | 1 | #include <stddef.h> |
| 2 | #include "dynlink.h" |
| 3 | |
| 4 | #ifdef SHARED |
| 5 | |
| 6 | #ifndef START |
| 7 | #define START "_dlstart" |
| 8 | #endif |
| 9 | |
| 10 | #include "crt_arch.h" |
| 11 | |
Rich Felker | 6fc30c2 | 2015-09-17 08:05:34 +0000 | [diff] [blame] | 12 | #ifndef GETFUNCSYM |
| 13 | #define GETFUNCSYM(fp, sym, got) do { \ |
| 14 | __attribute__((__visibility__("hidden"))) void sym(); \ |
| 15 | static void (*static_func_ptr)() = sym; \ |
| 16 | __asm__ __volatile__ ( "" : "+m"(static_func_ptr) : : "memory"); \ |
| 17 | *(fp) = static_func_ptr; } while(0) |
| 18 | #endif |
| 19 | |
Rich Felker | f1faa0e | 2015-04-14 00:28:30 -0400 | [diff] [blame] | 20 | __attribute__((__visibility__("hidden"))) |
Rich Felker | f3ddd17 | 2015-04-13 02:56:26 -0400 | [diff] [blame] | 21 | void _dlstart_c(size_t *sp, size_t *dynv) |
| 22 | { |
| 23 | size_t i, aux[AUX_CNT], dyn[DYN_CNT]; |
Rich Felker | d874064 | 2015-09-21 20:42:44 +0000 | [diff] [blame] | 24 | size_t *rel, rel_size, base; |
Rich Felker | f3ddd17 | 2015-04-13 02:56:26 -0400 | [diff] [blame] | 25 | |
| 26 | int argc = *sp; |
| 27 | char **argv = (void *)(sp+1); |
| 28 | |
| 29 | for (i=argc+1; argv[i]; i++); |
| 30 | size_t *auxv = (void *)(argv+i+1); |
| 31 | |
| 32 | for (i=0; i<AUX_CNT; i++) aux[i] = 0; |
| 33 | for (i=0; auxv[i]; i+=2) if (auxv[i]<AUX_CNT) |
| 34 | aux[auxv[i]] = auxv[i+1]; |
| 35 | |
| 36 | for (i=0; i<DYN_CNT; i++) dyn[i] = 0; |
| 37 | for (i=0; dynv[i]; i+=2) if (dynv[i]<DYN_CNT) |
| 38 | dyn[dynv[i]] = dynv[i+1]; |
| 39 | |
| 40 | /* If the dynamic linker is invoked as a command, its load |
| 41 | * address is not available in the aux vector. Instead, compute |
| 42 | * the load address as the difference between &_DYNAMIC and the |
| 43 | * virtual address in the PT_DYNAMIC program header. */ |
Rich Felker | d874064 | 2015-09-21 20:42:44 +0000 | [diff] [blame] | 44 | base = aux[AT_BASE]; |
Rich Felker | f3ddd17 | 2015-04-13 02:56:26 -0400 | [diff] [blame] | 45 | if (!base) { |
| 46 | size_t phnum = aux[AT_PHNUM]; |
| 47 | size_t phentsize = aux[AT_PHENT]; |
| 48 | Phdr *ph = (void *)aux[AT_PHDR]; |
| 49 | for (i=phnum; i--; ph = (void *)((char *)ph + phentsize)) { |
| 50 | if (ph->p_type == PT_DYNAMIC) { |
Rich Felker | d874064 | 2015-09-21 20:42:44 +0000 | [diff] [blame] | 51 | base = (size_t)dynv - ph->p_vaddr; |
Rich Felker | f3ddd17 | 2015-04-13 02:56:26 -0400 | [diff] [blame] | 52 | break; |
| 53 | } |
| 54 | } |
| 55 | } |
| 56 | |
| 57 | /* MIPS uses an ugly packed form for GOT relocations. Since we |
| 58 | * can't make function calls yet and the code is tiny anyway, |
| 59 | * it's simply inlined here. */ |
| 60 | if (NEED_MIPS_GOT_RELOCS) { |
| 61 | size_t local_cnt = 0; |
| 62 | size_t *got = (void *)(base + dyn[DT_PLTGOT]); |
| 63 | for (i=0; dynv[i]; i+=2) if (dynv[i]==DT_MIPS_LOCAL_GOTNO) |
| 64 | local_cnt = dynv[i+1]; |
Rich Felker | d874064 | 2015-09-21 20:42:44 +0000 | [diff] [blame] | 65 | for (i=0; i<local_cnt; i++) got[i] += base; |
Rich Felker | f3ddd17 | 2015-04-13 02:56:26 -0400 | [diff] [blame] | 66 | } |
| 67 | |
Rich Felker | 0e0e494 | 2015-05-25 00:32:37 -0400 | [diff] [blame] | 68 | rel = (void *)(base+dyn[DT_REL]); |
| 69 | rel_size = dyn[DT_RELSZ]; |
| 70 | for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t)) { |
| 71 | if (!IS_RELATIVE(rel[1])) continue; |
| 72 | size_t *rel_addr = (void *)(base + rel[0]); |
Rich Felker | d874064 | 2015-09-21 20:42:44 +0000 | [diff] [blame] | 73 | *rel_addr += base; |
Rich Felker | 0e0e494 | 2015-05-25 00:32:37 -0400 | [diff] [blame] | 74 | } |
| 75 | |
| 76 | rel = (void *)(base+dyn[DT_RELA]); |
| 77 | rel_size = dyn[DT_RELASZ]; |
| 78 | for (; rel_size; rel+=3, rel_size-=3*sizeof(size_t)) { |
| 79 | if (!IS_RELATIVE(rel[1])) continue; |
| 80 | size_t *rel_addr = (void *)(base + rel[0]); |
Rich Felker | d874064 | 2015-09-21 20:42:44 +0000 | [diff] [blame] | 81 | *rel_addr = base + rel[2]; |
Rich Felker | f3ddd17 | 2015-04-13 02:56:26 -0400 | [diff] [blame] | 82 | } |
| 83 | |
Rich Felker | 2907afb | 2015-09-17 06:30:55 +0000 | [diff] [blame] | 84 | stage2_func dls2; |
| 85 | GETFUNCSYM(&dls2, __dls2, base+dyn[DT_PLTGOT]); |
Rich Felker | d874064 | 2015-09-21 20:42:44 +0000 | [diff] [blame] | 86 | dls2((void *)base, sp); |
Rich Felker | f3ddd17 | 2015-04-13 02:56:26 -0400 | [diff] [blame] | 87 | } |
| 88 | |
| 89 | #endif |