diff options
Diffstat (limited to 'src/ldso/dlstart.c')
-rw-r--r-- | src/ldso/dlstart.c | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/src/ldso/dlstart.c b/src/ldso/dlstart.c new file mode 100644 index 00000000..5bd2a080 --- /dev/null +++ b/src/ldso/dlstart.c @@ -0,0 +1,107 @@ +#include <stddef.h> +#include "dynlink.h" + +#ifdef SHARED + +#ifndef START +#define START "_dlstart" +#endif + +#include "crt_arch.h" + +void _dlstart_c(size_t *sp, size_t *dynv) +{ + size_t i, aux[AUX_CNT], dyn[DYN_CNT]; + + int argc = *sp; + char **argv = (void *)(sp+1); + + for (i=argc+1; argv[i]; i++); + size_t *auxv = (void *)(argv+i+1); + + for (i=0; i<AUX_CNT; i++) aux[i] = 0; + for (i=0; auxv[i]; i+=2) if (auxv[i]<AUX_CNT) + aux[auxv[i]] = auxv[i+1]; + + for (i=0; i<DYN_CNT; i++) dyn[i] = 0; + for (i=0; dynv[i]; i+=2) if (dynv[i]<DYN_CNT) + dyn[dynv[i]] = dynv[i+1]; + + /* If the dynamic linker is invoked as a command, its load + * address is not available in the aux vector. Instead, compute + * the load address as the difference between &_DYNAMIC and the + * virtual address in the PT_DYNAMIC program header. */ + unsigned char *base = (void *)aux[AT_BASE]; + if (!base) { + size_t phnum = aux[AT_PHNUM]; + size_t phentsize = aux[AT_PHENT]; + Phdr *ph = (void *)aux[AT_PHDR]; + for (i=phnum; i--; ph = (void *)((char *)ph + phentsize)) { + if (ph->p_type == PT_DYNAMIC) { + base = (void *)((size_t)dynv - ph->p_vaddr); + break; + } + } + } + + /* MIPS uses an ugly packed form for GOT relocations. Since we + * can't make function calls yet and the code is tiny anyway, + * it's simply inlined here. */ + if (NEED_MIPS_GOT_RELOCS) { + size_t local_cnt = 0; + size_t *got = (void *)(base + dyn[DT_PLTGOT]); + for (i=0; dynv[i]; i+=2) if (dynv[i]==DT_MIPS_LOCAL_GOTNO) + local_cnt = dynv[i+1]; + for (i=0; i<local_cnt; i++) got[i] += (size_t)base; + } + + /* The use of the reloc_info structure and nested loops is a trick + * to work around the fact that we can't necessarily make function + * calls yet. Each struct in the array serves like the arguments + * to a function call. */ + struct { + void *rel; + size_t size; + size_t stride; + } reloc_info[] = { + { base+dyn[DT_JMPREL], dyn[DT_PLTRELSZ], 2+(dyn[DT_PLTREL]==DT_RELA) }, + { base+dyn[DT_REL], dyn[DT_RELSZ], 2 }, + { base+dyn[DT_RELA], dyn[DT_RELASZ], 3 }, + { 0, 0, 0 } + }; + + for (i=0; reloc_info[i].stride; i++) { + size_t *rel = reloc_info[i].rel; + size_t rel_size = reloc_info[i].size; + size_t stride = reloc_info[i].stride; + for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) { + if (!IS_RELATIVE(rel[1])) continue; + size_t *rel_addr = (void *)(base + rel[0]); + size_t addend = stride==3 ? rel[2] : *rel_addr; + *rel_addr = (size_t)base + addend; + } + } + + const char *strings = (void *)(base + dyn[DT_STRTAB]); + const Sym *syms = (void *)(base + dyn[DT_SYMTAB]); + + /* Call dynamic linker stage-2, __dls2 */ + for (i=0; ;i++) { + const char *s = strings + syms[i].st_name; + if (s[0]=='_' && s[1]=='_' && s[2]=='d' + && s[3]=='l' && s[4]=='s' && s[5]=='2' && !s[6]) + break; + } + ((stage2_func)(base + syms[i].st_value))(base); + + /* Call dynamic linker stage-3, __dls3 */ + for (i=0; ;i++) { + const char *s = strings + syms[i].st_name; + if (s[0]=='_' && s[1]=='_' && s[2]=='d' + && s[3]=='l' && s[4]=='s' && s[5]=='3' && !s[6]) + break; + } + ((stage3_func)(base + syms[i].st_value))(sp); +} + +#endif |