149 lines
4.3 KiB
C
149 lines
4.3 KiB
C
#include <stddef.h>
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#include "dynlink.h"
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#include "libc.h"
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#ifndef START
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#define START "_dlstart"
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#endif
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#define SHARED
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#include "crt_arch.h"
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#ifndef GETFUNCSYM
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#define GETFUNCSYM(fp, sym, got) do { \
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hidden void sym(); \
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static void (*static_func_ptr)() = sym; \
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__asm__ __volatile__ ( "" : "+m"(static_func_ptr) : : "memory"); \
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*(fp) = static_func_ptr; } while(0)
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#endif
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hidden void _dlstart_c(size_t *sp, size_t *dynv)
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{
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size_t i, aux[AUX_CNT], dyn[DYN_CNT];
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size_t *rel, rel_size, base;
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int argc = *sp;
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char **argv = (void *)(sp+1);
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for (i=argc+1; argv[i]; i++);
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size_t *auxv = (void *)(argv+i+1);
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for (i=0; i<AUX_CNT; i++) aux[i] = 0;
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for (i=0; auxv[i]; i+=2) if (auxv[i]<AUX_CNT)
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aux[auxv[i]] = auxv[i+1];
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#if DL_FDPIC
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struct fdpic_loadseg *segs, fakeseg;
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size_t j;
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if (dynv) {
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/* crt_arch.h entry point asm is responsible for reserving
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* space and moving the extra fdpic arguments to the stack
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* vector where they are easily accessible from C. */
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segs = ((struct fdpic_loadmap *)(sp[-1] ? sp[-1] : sp[-2]))->segs;
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} else {
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/* If dynv is null, the entry point was started from loader
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* that is not fdpic-aware. We can assume normal fixed-
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* displacement ELF loading was performed, but when ldso was
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* run as a command, finding the Ehdr is a heursitic: we
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* have to assume Phdrs start in the first 4k of the file. */
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base = aux[AT_BASE];
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if (!base) base = aux[AT_PHDR] & -4096;
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segs = &fakeseg;
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segs[0].addr = base;
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segs[0].p_vaddr = 0;
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segs[0].p_memsz = -1;
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Ehdr *eh = (void *)base;
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Phdr *ph = (void *)(base + eh->e_phoff);
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size_t phnum = eh->e_phnum;
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size_t phent = eh->e_phentsize;
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while (phnum-- && ph->p_type != PT_DYNAMIC)
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ph = (void *)((size_t)ph + phent);
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dynv = (void *)(base + ph->p_vaddr);
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}
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#endif
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for (i=0; i<DYN_CNT; i++) dyn[i] = 0;
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for (i=0; dynv[i]; i+=2) if (dynv[i]<DYN_CNT)
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dyn[dynv[i]] = dynv[i+1];
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#if DL_FDPIC
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for (i=0; i<DYN_CNT; i++) {
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if (i==DT_RELASZ || i==DT_RELSZ) continue;
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if (!dyn[i]) continue;
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for (j=0; dyn[i]-segs[j].p_vaddr >= segs[j].p_memsz; j++);
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dyn[i] += segs[j].addr - segs[j].p_vaddr;
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}
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base = 0;
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const Sym *syms = (void *)dyn[DT_SYMTAB];
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rel = (void *)dyn[DT_RELA];
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rel_size = dyn[DT_RELASZ];
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for (; rel_size; rel+=3, rel_size-=3*sizeof(size_t)) {
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if (!IS_RELATIVE(rel[1], syms)) continue;
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for (j=0; rel[0]-segs[j].p_vaddr >= segs[j].p_memsz; j++);
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size_t *rel_addr = (void *)
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(rel[0] + segs[j].addr - segs[j].p_vaddr);
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if (R_TYPE(rel[1]) == REL_FUNCDESC_VAL) {
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*rel_addr += segs[rel_addr[1]].addr
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- segs[rel_addr[1]].p_vaddr
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+ syms[R_SYM(rel[1])].st_value;
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rel_addr[1] = dyn[DT_PLTGOT];
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} else {
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size_t val = syms[R_SYM(rel[1])].st_value;
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for (j=0; val-segs[j].p_vaddr >= segs[j].p_memsz; j++);
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*rel_addr = rel[2] + segs[j].addr - segs[j].p_vaddr + val;
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}
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}
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#else
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/* If the dynamic linker is invoked as a command, its load
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* address is not available in the aux vector. Instead, compute
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* the load address as the difference between &_DYNAMIC and the
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* virtual address in the PT_DYNAMIC program header. */
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base = aux[AT_BASE];
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if (!base) {
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size_t phnum = aux[AT_PHNUM];
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size_t phentsize = aux[AT_PHENT];
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Phdr *ph = (void *)aux[AT_PHDR];
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for (i=phnum; i--; ph = (void *)((char *)ph + phentsize)) {
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if (ph->p_type == PT_DYNAMIC) {
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base = (size_t)dynv - ph->p_vaddr;
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break;
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}
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}
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}
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/* MIPS uses an ugly packed form for GOT relocations. Since we
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* can't make function calls yet and the code is tiny anyway,
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* it's simply inlined here. */
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if (NEED_MIPS_GOT_RELOCS) {
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size_t local_cnt = 0;
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size_t *got = (void *)(base + dyn[DT_PLTGOT]);
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for (i=0; dynv[i]; i+=2) if (dynv[i]==DT_MIPS_LOCAL_GOTNO)
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local_cnt = dynv[i+1];
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for (i=0; i<local_cnt; i++) got[i] += base;
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}
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rel = (void *)(base+dyn[DT_REL]);
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rel_size = dyn[DT_RELSZ];
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for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t)) {
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if (!IS_RELATIVE(rel[1], 0)) continue;
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size_t *rel_addr = (void *)(base + rel[0]);
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*rel_addr += base;
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}
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rel = (void *)(base+dyn[DT_RELA]);
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rel_size = dyn[DT_RELASZ];
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for (; rel_size; rel+=3, rel_size-=3*sizeof(size_t)) {
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if (!IS_RELATIVE(rel[1], 0)) continue;
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size_t *rel_addr = (void *)(base + rel[0]);
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*rel_addr = base + rel[2];
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}
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#endif
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stage2_func dls2;
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GETFUNCSYM(&dls2, __dls2, base+dyn[DT_PLTGOT]);
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dls2((void *)base, sp);
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}
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