diff options
| -rw-r--r-- | src/ldso/dynlink.c | 54 |
1 files changed, 43 insertions, 11 deletions
diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c index 3842aeba..42930adf 100644 --- a/src/ldso/dynlink.c +++ b/src/ldso/dynlink.c @@ -74,7 +74,6 @@ struct dso { volatile int new_dtv_idx, new_tls_idx; struct td_index *td_index; struct dso *fini_next; - int rel_early_relative, rel_update_got; char *shortname; char buf[]; }; @@ -96,6 +95,9 @@ static struct builtin_tls { } builtin_tls[1]; #define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt) +#define ADDEND_LIMIT 4096 +static size_t *saved_addends, *apply_addends_to; + static struct dso ldso; static struct dso *head, *tail, *fini_head; static char *env_path, *sys_path; @@ -256,9 +258,17 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri size_t sym_val; size_t tls_val; size_t addend; + int skip_relative = 0, reuse_addends = 0, save_slot = 0; + + if (dso == &ldso) { + /* Only ldso's REL table needs addend saving/reuse. */ + if (rel == apply_addends_to) + reuse_addends = 1; + skip_relative = 1; + } for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) { - if (dso->rel_early_relative && IS_RELATIVE(rel[1])) continue; + if (skip_relative && IS_RELATIVE(rel[1])) continue; type = R_TYPE(rel[1]); sym_index = R_SYM(rel[1]); reloc_addr = (void *)(base + rel[0]); @@ -280,12 +290,20 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri def.dso = dso; } - int gotplt = (type == REL_GOT || type == REL_PLT); - if (dso->rel_update_got && !gotplt && stride==2) continue; - - addend = stride>2 ? rel[2] - : gotplt || type==REL_COPY ? 0 - : *reloc_addr; + if (stride > 2) { + addend = rel[2]; + } else if (type==REL_GOT || type==REL_PLT|| type==REL_COPY) { + addend = 0; + } else if (reuse_addends) { + /* Save original addend in stage 2 where the dso + * chain consists of just ldso; otherwise read back + * saved addend since the inline one was clobbered. */ + if (head==&ldso) + saved_addends[save_slot] = *reloc_addr; + addend = saved_addends[save_slot++]; + } else { + addend = *reloc_addr; + } sym_val = def.sym ? (size_t)def.dso->base+def.sym->st_value : 0; tls_val = def.sym ? def.sym->st_value : 0; @@ -879,7 +897,7 @@ static void do_mips_relocs(struct dso *p, size_t *got) size_t i, j, rel[2]; unsigned char *base = p->base; i=0; search_vec(p->dynv, &i, DT_MIPS_LOCAL_GOTNO); - if (p->rel_early_relative) { + if (p==&ldso) { got += i; } else { while (i--) *got++ += (size_t)base; @@ -1125,15 +1143,29 @@ void __dls2(unsigned char *base, size_t *sp) ldso.phnum = ehdr->e_phnum; ldso.phdr = (void *)(base + ehdr->e_phoff); ldso.phentsize = ehdr->e_phentsize; - ldso.rel_early_relative = 1; kernel_mapped_dso(&ldso); decode_dyn(&ldso); + /* Prepare storage for to save clobbered REL addends so they + * can be reused in stage 3. There should be very few. If + * something goes wrong and there are a huge number, abort + * instead of risking stack overflow. */ + size_t dyn[DYN_CNT]; + decode_vec(ldso.dynv, dyn, DYN_CNT); + size_t *rel = (void *)(base+dyn[DT_REL]); + size_t rel_size = dyn[DT_RELSZ]; + size_t symbolic_rel_cnt = 0; + apply_addends_to = rel; + for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t)) + if (!IS_RELATIVE(rel[1])) symbolic_rel_cnt++; + if (symbolic_rel_cnt >= ADDEND_LIMIT) a_crash(); + size_t addends[symbolic_rel_cnt+1]; + saved_addends = addends; + head = &ldso; reloc_all(&ldso); ldso.relocated = 0; - ldso.rel_update_got = 1; /* Call dynamic linker stage-3, __dls3, looking it up * symbolically as a barrier against moving the address |