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authorRich Felker <dalias@aerifal.cx>2012-10-04 22:48:33 -0400
committerRich Felker <dalias@aerifal.cx>2012-10-04 22:48:33 -0400
commit9c74856af78ac3e8aaa5f8b560e5022d2e6037d1 (patch)
tree2cab0360309f85ae6ec132ac46d4d31cd7038abb /src/ldso
parentc91aa03d2488ef2c48276510dec360ed9582e861 (diff)
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dynamic-linked TLS support for everything but dlopen'd libs
currently, only i386 is tested. x86_64 and arm should probably work. the necessary relocation types for mips and microblaze have not been added because I don't understand how they're supposed to work, and I'm not even sure if it's defined yet on microblaze. I may be able to reverse engineer the requirements out of gcc/binutils output.
Diffstat (limited to 'src/ldso')
-rw-r--r--src/ldso/dynlink.c96
1 files changed, 58 insertions, 38 deletions
diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c
index 8ff8e696..e09f0715 100644
--- a/src/ldso/dynlink.c
+++ b/src/ldso/dynlink.c
@@ -68,11 +68,16 @@ struct dso {
char constructed;
struct dso **deps;
void *tls_image;
- size_t tls_len, tls_size, tls_align, tls_id;
+ size_t tls_len, tls_size, tls_align, tls_id, tls_offset;
char *shortname;
char buf[];
};
+struct symdef {
+ Sym *sym;
+ struct dso *dso;
+};
+
#include "reloc.h"
void __init_ssp(size_t *);
@@ -172,13 +177,13 @@ static Sym *gnu_lookup(const char *s, uint32_t h1, struct dso *dso)
return 0;
}
-#define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON)
+#define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
#define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK)
-static void *find_sym(struct dso *dso, const char *s, int need_def)
+static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
{
uint32_t h = 0, gh = 0;
- void *def = 0;
+ struct symdef def = {0};
if (dso->ghashtab) {
gh = gnu_hash(s);
if (gh == 0x1f4039c9 && !strcmp(s, "__stack_chk_fail")) ssp_used = 1;
@@ -199,8 +204,9 @@ static void *find_sym(struct dso *dso, const char *s, int need_def)
if (sym && (!need_def || sym->st_shndx) && sym->st_value
&& (1<<(sym->st_info&0xf) & OK_TYPES)
&& (1<<(sym->st_info>>4) & OK_BINDS)) {
- if (def && sym->st_info>>4 == STB_WEAK) continue;
- def = dso->base + sym->st_value;
+ if (def.sym && sym->st_info>>4 == STB_WEAK) continue;
+ def.sym = sym;
+ def.dso = dso;
if (sym->st_info>>4 == STB_GLOBAL) break;
}
}
@@ -214,22 +220,20 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri
char *strings = dso->strings;
Sym *sym;
const char *name;
- size_t sym_val, sym_size;
- size_t *reloc_addr;
void *ctx;
int type;
int sym_index;
+ struct symdef def;
for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
- reloc_addr = (void *)(base + rel[0]);
type = R_TYPE(rel[1]);
sym_index = R_SYM(rel[1]);
if (sym_index) {
sym = syms + sym_index;
name = strings + sym->st_name;
ctx = IS_COPY(type) ? head->next : head;
- sym_val = (size_t)find_sym(ctx, name, IS_PLT(type));
- if (!sym_val && sym->st_info>>4 != STB_WEAK) {
+ def = find_sym(ctx, name, IS_PLT(type));
+ if (!def.sym && sym->st_info>>4 != STB_WEAK) {
snprintf(errbuf, sizeof errbuf,
"Error relocating %s: %s: symbol not found",
dso->name, name);
@@ -238,11 +242,14 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri
ldso_fail = 1;
continue;
}
- sym_size = sym->st_size;
} else {
- sym_val = sym_size = 0;
+ sym = 0;
+ def.sym = 0;
+ def.dso = 0;
}
- do_single_reloc(reloc_addr, type, sym_val, sym_size, base, rel[2]);
+ do_single_reloc(dso, base, (void *)(base + rel[0]), type,
+ stride>2 ? rel[2] : 0, sym, sym?sym->st_size:0, def,
+ def.sym?(size_t)(def.dso->base+def.sym->st_value):0);
}
}
@@ -816,9 +823,38 @@ void *__dynlink(int argc, char **argv)
if (env_preload) load_preload(env_preload);
load_deps(app);
make_global(app);
+
+ /* Make an initial pass setting up TLS before performing relocs.
+ * This provides the TP-based offset of each DSO's TLS for
+ * use in TP-relative relocations. After relocations, we need
+ * to copy the TLS images again in case they had relocs. */
+ tls_size += sizeof(struct pthread) + 4*sizeof(size_t);
+ __libc.tls_size = tls_size;
+ __libc.tls_cnt = tls_cnt;
+ if (tls_cnt) {
+ struct dso *p;
+ void *mem = mmap(0, __libc.tls_size, PROT_READ|PROT_WRITE,
+ MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+ if (mem==MAP_FAILED ||
+ !__install_initial_tls(__copy_tls(mem, tls_cnt))) {
+ dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
+ argv[0], tls_size);
+ _exit(127);
+ }
+ for (p=head; p; p=p->next) {
+ if (!p->tls_id) continue;
+ p->tls_offset = (char *)__pthread_self()
+ - (char *)__pthread_self()->dtv[p->tls_id];
+ }
+ }
+
reloc_all(app->next);
reloc_all(app);
+ /* The initial DTV is located at the base of the memory
+ * allocated for TLS. Repeat copying TLS to pick up relocs. */
+ if (tls_cnt) __copy_tls((void *)__pthread_self()->dtv, tls_cnt);
+
if (ldso_fail) _exit(127);
if (ldd_mode) _exit(0);
@@ -840,19 +876,6 @@ void *__dynlink(int argc, char **argv)
debug.state = 0;
_dl_debug_state();
- tls_size += sizeof(struct pthread) + 4*sizeof(size_t);
- __libc.tls_size = tls_size;
- __libc.tls_cnt = tls_cnt;
- if (tls_cnt) {
- void *mem = mmap(0, __libc.tls_size, PROT_READ|PROT_WRITE,
- MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
- if (mem==MAP_FAILED ||
- !__install_initial_tls(__copy_tls(mem, tls_cnt))) {
- dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
- argv[0], tls_size);
- _exit(127);
- }
- }
if (ssp_used) __init_ssp(auxv);
do_init_fini(tail);
@@ -933,17 +956,14 @@ static void *do_dlsym(struct dso *p, const char *s, void *ra)
size_t i;
uint32_t h = 0, gh = 0;
Sym *sym;
- if (p == RTLD_NEXT) {
- for (p=head; p && (unsigned char *)ra-p->map>p->map_len; p=p->next);
- if (!p) p=head;
- void *res = find_sym(p->next, s, 0);
- if (!res) goto failed;
- return res;
- }
- if (p == head || p == RTLD_DEFAULT) {
- void *res = find_sym(head, s, 0);
- if (!res) goto failed;
- return res;
+ if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
+ if (p == RTLD_NEXT) {
+ for (p=head; p && (unsigned char *)ra-p->map>p->map_len; p=p->next);
+ if (!p) p=head;
+ }
+ struct symdef def = find_sym(p->next, s, 0);
+ if (!def.sym) goto failed;
+ return def.dso->base + def.sym->st_value;
}
if (p->ghashtab) {
gh = gnu_hash(s);