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authorRich Felker <dalias@aerifal.cx>2012-10-04 16:35:46 -0400
committerRich Felker <dalias@aerifal.cx>2012-10-04 16:35:46 -0400
commit8431d7972fd9be0fdcaff8516316d748e81724bb (patch)
tree53800c9deeaf26a9fedc5f9f574d9694315b510c /src/thread/pthread_create.c
parentadefe830dd376be386df5650a09c313c483adf1a (diff)
downloadmusl-8431d7972fd9be0fdcaff8516316d748e81724bb.tar.gz
TLS (GNU/C11 thread-local storage) support for static-linked programs
the design for TLS in dynamic-linked programs is mostly complete too, but I have not yet implemented it. cost is nonzero but still low for programs which do not use TLS and/or do not use threads (a few hundred bytes of new code, plus dependency on memcpy). i believe it can be made smaller at some point by merging __init_tls and __init_security into __libc_start_main and avoiding duplicate auxv-parsing code. at the same time, I've also slightly changed the logic pthread_create uses to allocate guard pages to ensure that guard pages are not counted towards commit charge.
Diffstat (limited to 'src/thread/pthread_create.c')
-rw-r--r--src/thread/pthread_create.c23
1 files changed, 18 insertions, 5 deletions
diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index d8b8f0fc..f53fc1ba 100644
--- a/src/thread/pthread_create.c
+++ b/src/thread/pthread_create.c
@@ -84,6 +84,8 @@ static void init_file_lock(FILE *f)
if (f && f->lock<0) f->lock = 0;
}
+void *__copy_tls(unsigned char *, size_t);
+
int pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attr, void *(*entry)(void *), void *restrict arg)
{
int ret;
@@ -92,6 +94,8 @@ int pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attr,
struct pthread *self = pthread_self(), *new;
unsigned char *map, *stack, *tsd;
unsigned flags = 0x7d8f00;
+ size_t tls_cnt = libc.tls_cnt;
+ size_t tls_size = libc.tls_size;
if (!self) return ENOSYS;
if (!libc.threaded) {
@@ -109,15 +113,24 @@ int pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attr,
} else {
if (attr) {
guard = ROUND(attr->_a_guardsize + DEFAULT_GUARD_SIZE);
- size = guard + ROUND(attr->_a_stacksize + DEFAULT_STACK_SIZE);
+ size = guard + ROUND(attr->_a_stacksize
+ + DEFAULT_STACK_SIZE + tls_size);
}
size += __pthread_tsd_size;
- map = mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
- if (map == MAP_FAILED) return EAGAIN;
- if (guard) mprotect(map, guard, PROT_NONE);
+ if (guard) {
+ map = mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANON, -1, 0);
+ if (map == MAP_FAILED) return EAGAIN;
+ if (mprotect(map+guard, size-guard, PROT_READ|PROT_WRITE)) {
+ munmap(map, size);
+ return EAGAIN;
+ }
+ } else {
+ map = mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
+ if (map == MAP_FAILED) return EAGAIN;
+ }
tsd = map + size - __pthread_tsd_size;
}
- new = (void *)(tsd - sizeof *new - PAGE_SIZE%sizeof *new);
+ new = __copy_tls(tsd - tls_size, tls_cnt);
new->map_base = map;
new->map_size = size;
new->pid = self->pid;