| #include <stddef.h> |
| #include "dynlink.h" |
| #include "libc.h" |
| |
| #ifndef START |
| #define START "_dlstart" |
| #endif |
| |
| #define SHARED |
| |
| #include "crt_arch.h" |
| |
| #ifndef GETFUNCSYM |
| #define GETFUNCSYM(fp, sym, got) do { \ |
| hidden void sym(); \ |
| static void (*static_func_ptr)() = sym; \ |
| __asm__ __volatile__ ( "" : "+m"(static_func_ptr) : : "memory"); \ |
| *(fp) = static_func_ptr; } while(0) |
| #endif |
| |
| hidden void _dlstart_c(size_t *sp, size_t *dynv) |
| { |
| size_t i, aux[AUX_CNT], dyn[DYN_CNT]; |
| size_t *rel, rel_size, base; |
| |
| 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]; |
| |
| #if DL_FDPIC |
| struct fdpic_loadseg *segs, fakeseg; |
| size_t j; |
| if (dynv) { |
| /* crt_arch.h entry point asm is responsible for reserving |
| * space and moving the extra fdpic arguments to the stack |
| * vector where they are easily accessible from C. */ |
| segs = ((struct fdpic_loadmap *)(sp[-1] ? sp[-1] : sp[-2]))->segs; |
| } else { |
| /* If dynv is null, the entry point was started from loader |
| * that is not fdpic-aware. We can assume normal fixed- |
| * displacement ELF loading was performed, but when ldso was |
| * run as a command, finding the Ehdr is a heursitic: we |
| * have to assume Phdrs start in the first 4k of the file. */ |
| base = aux[AT_BASE]; |
| if (!base) base = aux[AT_PHDR] & -4096; |
| segs = &fakeseg; |
| segs[0].addr = base; |
| segs[0].p_vaddr = 0; |
| segs[0].p_memsz = -1; |
| Ehdr *eh = (void *)base; |
| Phdr *ph = (void *)(base + eh->e_phoff); |
| size_t phnum = eh->e_phnum; |
| size_t phent = eh->e_phentsize; |
| while (phnum-- && ph->p_type != PT_DYNAMIC) |
| ph = (void *)((size_t)ph + phent); |
| dynv = (void *)(base + ph->p_vaddr); |
| } |
| #endif |
| |
| 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 DL_FDPIC |
| for (i=0; i<DYN_CNT; i++) { |
| if (i==DT_RELASZ || i==DT_RELSZ) continue; |
| if (!dyn[i]) continue; |
| for (j=0; dyn[i]-segs[j].p_vaddr >= segs[j].p_memsz; j++); |
| dyn[i] += segs[j].addr - segs[j].p_vaddr; |
| } |
| base = 0; |
| |
| const Sym *syms = (void *)dyn[DT_SYMTAB]; |
| |
| rel = (void *)dyn[DT_RELA]; |
| rel_size = dyn[DT_RELASZ]; |
| for (; rel_size; rel+=3, rel_size-=3*sizeof(size_t)) { |
| if (!IS_RELATIVE(rel[1], syms)) continue; |
| for (j=0; rel[0]-segs[j].p_vaddr >= segs[j].p_memsz; j++); |
| size_t *rel_addr = (void *) |
| (rel[0] + segs[j].addr - segs[j].p_vaddr); |
| if (R_TYPE(rel[1]) == REL_FUNCDESC_VAL) { |
| *rel_addr += segs[rel_addr[1]].addr |
| - segs[rel_addr[1]].p_vaddr |
| + syms[R_SYM(rel[1])].st_value; |
| rel_addr[1] = dyn[DT_PLTGOT]; |
| } else { |
| size_t val = syms[R_SYM(rel[1])].st_value; |
| for (j=0; val-segs[j].p_vaddr >= segs[j].p_memsz; j++); |
| *rel_addr = rel[2] + segs[j].addr - segs[j].p_vaddr + val; |
| } |
| } |
| #else |
| /* 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. */ |
| base = 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 = (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] += base; |
| } |
| |
| rel = (void *)(base+dyn[DT_REL]); |
| rel_size = dyn[DT_RELSZ]; |
| for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t)) { |
| if (!IS_RELATIVE(rel[1], 0)) continue; |
| size_t *rel_addr = (void *)(base + rel[0]); |
| *rel_addr += base; |
| } |
| |
| rel = (void *)(base+dyn[DT_RELA]); |
| rel_size = dyn[DT_RELASZ]; |
| for (; rel_size; rel+=3, rel_size-=3*sizeof(size_t)) { |
| if (!IS_RELATIVE(rel[1], 0)) continue; |
| size_t *rel_addr = (void *)(base + rel[0]); |
| *rel_addr = base + rel[2]; |
| } |
| #endif |
| |
| stage2_func dls2; |
| GETFUNCSYM(&dls2, __dls2, base+dyn[DT_PLTGOT]); |
| dls2((void *)base, sp); |
| } |