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partial TLS support for dynamic-linked programs

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only TLS in the main program is supported so far; TLS defined in
shared libraries will not work yet.
This commit is contained in:
Rich Felker 2012-10-04 20:04:13 -04:00
parent 8431d7972f
commit bc6a35fb7b
2 changed files with 77 additions and 27 deletions
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10
src/env/__init_tls.c vendored
View File

@ -7,13 +7,14 @@
#ifndef SHARED
static void *image;
static size_t len, bss, align;
static size_t len, size, align;
void *__copy_tls(unsigned char *mem, size_t cnt)
{
mem += -size & (4*sizeof(size_t)-1);
mem += ((uintptr_t)image - (uintptr_t)mem) & (align-1);
memcpy(mem, image, len);
return mem + len + bss;
return mem + size;
}
static void *simple(void *p)
@ -53,13 +54,12 @@ void __init_tls(size_t *auxv)
}
if (!tls_phdr) return;
libc.tls_size = len+bss+align+4*sizeof(size_t)+sizeof(struct pthread);
libc.tls_size = size+align+8*sizeof(size_t)+sizeof(struct pthread);
image = (void *)(base + tls_phdr->p_vaddr);
len = tls_phdr->p_filesz;
bss = tls_phdr->p_memsz - len;
size = tls_phdr->p_memsz;
align = tls_phdr->p_align;
if (align < 4*sizeof(size_t)) align = 4*sizeof(size_t);
mem = __mmap(0, libc.tls_size, PROT_READ|PROT_WRITE,
MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
if (mem == MAP_FAILED) a_crash();

94
src/ldso/dynlink.c
View File

@ -67,6 +67,8 @@ struct dso {
char relocated;
char constructed;
struct dso **deps;
void *tls_image;
size_t tls_len, tls_size, tls_align, tls_id;
char *shortname;
char buf[];
};
@ -74,6 +76,7 @@ struct dso {
#include "reloc.h"
void __init_ssp(size_t *);
void *__install_initial_tls(void *);
static struct dso *head, *tail, *libc;
static char *env_path, *sys_path, *r_path;
@ -86,6 +89,7 @@ static jmp_buf rtld_fail;
static pthread_rwlock_t lock;
static struct debug debug;
static size_t *auxv;
static size_t tls_cnt, tls_size;
struct debug *_dl_debug_addr = &debug;
@ -278,7 +282,7 @@ static void reclaim_gaps(unsigned char *base, Phdr *ph, size_t phent, size_t phc
}
}
static void *map_library(int fd, size_t *lenp, unsigned char **basep, size_t *dynp)
static void *map_library(int fd, struct dso *dso)
{
Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
size_t phsize;
@ -290,6 +294,7 @@ static void *map_library(int fd, size_t *lenp, unsigned char **basep, size_t *dy
unsigned prot;
unsigned char *map, *base;
size_t dyn;
size_t tls_image=0;
size_t i;
ssize_t l = read(fd, buf, sizeof buf);
@ -306,6 +311,12 @@ static void *map_library(int fd, size_t *lenp, unsigned char **basep, size_t *dy
for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
if (ph->p_type == PT_DYNAMIC)
dyn = ph->p_vaddr;
if (ph->p_type == PT_TLS) {
tls_image = ph->p_vaddr;
dso->tls_align = ph->p_align;
dso->tls_len = ph->p_filesz;
dso->tls_size = ph->p_memsz;
}
if (ph->p_type != PT_LOAD) continue;
if (ph->p_vaddr < addr_min) {
addr_min = ph->p_vaddr;
@ -360,9 +371,11 @@ static void *map_library(int fd, size_t *lenp, unsigned char **basep, size_t *dy
}
if (!runtime) reclaim_gaps(base, (void *)((char *)buf + eh->e_phoff),
eh->e_phentsize, eh->e_phnum);
*lenp = map_len;
*basep = base;
*dynp = dyn;
dso->map = map;
dso->map_len = map_len;
dso->base = base;
dso->dynv = (void *)(base+dyn);
if (dso->tls_size) dso->tls_image = (void *)(base+tls_image);
return map;
error:
munmap(map, map_len);
@ -402,7 +415,7 @@ static struct dso *load_library(const char *name)
const char *pathname;
unsigned char *base, *map;
size_t dyno, map_len;
struct dso *p;
struct dso *p, temp_dso = {0};
int fd;
struct stat st;
@ -469,21 +482,21 @@ static struct dso *load_library(const char *name)
return p;
}
}
map = map_library(fd, &map_len, &base, &dyno);
map = map_library(fd, &temp_dso);
close(fd);
if (!map) return 0;
p = calloc(1, sizeof *p + strlen(pathname) + 1);
p = malloc(sizeof *p + strlen(pathname) + 1);
if (!p) {
munmap(map, map_len);
return 0;
}
p->map = map;
p->map_len = map_len;
p->base = base;
p->dynv = (void *)(base + dyno);
memcpy(p, &temp_dso, sizeof temp_dso);
decode_dyn(p);
if (p->tls_image) {
p->tls_id = ++tls_cnt;
tls_size += p->tls_size + p->tls_align + 8*sizeof(size_t) - 1
& -4*sizeof(size_t);
}
p->dev = st.st_dev;
p->ino = st.st_ino;
p->refcnt = 1;
@ -622,6 +635,25 @@ void _dl_debug_state(void)
{
}
void *__copy_tls(unsigned char *mem, size_t cnt)
{
struct dso *p;
void **dtv = (void *)mem;
dtv[0] = (void *)cnt;
mem = (void *)(dtv + cnt + 1);
for (p=tail; p; p=p->prev) {
if (p->tls_id-1 >= cnt) continue;
mem += -p->tls_len & (4*sizeof(size_t)-1);
mem += ((uintptr_t)p->tls_image - (uintptr_t)mem)
& (p->tls_align-1);
dtv[p->tls_id] = mem;
memcpy(mem, p->tls_image, p->tls_len);
mem += p->tls_size;
}
((pthread_t)mem)->dtv = dtv;
return mem;
}
void *__dynlink(int argc, char **argv)
{
size_t aux[AUX_CNT] = {0};
@ -676,6 +708,7 @@ void *__dynlink(int argc, char **argv)
if (aux[AT_PHDR]) {
size_t interp_off = 0;
size_t tls_image = 0;
/* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
phdr = (void *)aux[AT_PHDR];
for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
@ -683,7 +716,14 @@ void *__dynlink(int argc, char **argv)
app->base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
else if (phdr->p_type == PT_INTERP)
interp_off = (size_t)phdr->p_vaddr;
else if (phdr->p_type == PT_TLS) {
tls_image = phdr->p_vaddr;
app->tls_len = phdr->p_filesz;
app->tls_size = phdr->p_memsz;
app->tls_align = phdr->p_align;
}
}
if (app->tls_size) app->tls_image = (char *)app->base + tls_image;
if (interp_off) lib->name = (char *)app->base + interp_off;
app->name = argv[0];
app->dynv = (void *)(app->base + find_dyn(
@ -709,7 +749,7 @@ void *__dynlink(int argc, char **argv)
_exit(1);
}
runtime = 1;
ehdr = (void *)map_library(fd, &app->map_len, &app->base, &dyno);
ehdr = (void *)map_library(fd, app);
if (!ehdr) {
dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
_exit(1);
@ -718,9 +758,13 @@ void *__dynlink(int argc, char **argv)
close(fd);
lib->name = ldname;
app->name = argv[0];
app->dynv = (void *)(app->base + dyno);
aux[AT_ENTRY] = ehdr->e_entry;
}
if (app->tls_size) {
app->tls_id = ++tls_cnt;
tls_size += app->tls_size+app->tls_align + 8*sizeof(size_t)-1
& -4*sizeof(size_t);
}
app->global = 1;
app->constructed = 1;
decode_dyn(app);
@ -791,8 +835,19 @@ void *__dynlink(int argc, char **argv)
debug.state = 0;
_dl_debug_state();
/* Stand-in until real TLS support is added to dynamic linker */
__libc.tls_size = sizeof(struct pthread) + 4*sizeof(size_t);
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);
@ -807,11 +862,6 @@ void *__dynlink(int argc, char **argv)
return (void *)aux[AT_ENTRY];
}
void *__copy_tls(unsigned char *mem, size_t cnt)
{
return mem;
}
void *dlopen(const char *file, int mode)
{
struct dso *volatile p, *orig_tail = tail, *next;