From 8431d7972fd9be0fdcaff8516316d748e81724bb Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Thu, 4 Oct 2012 16:35:46 -0400 Subject: 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. --- src/thread/pthread_create.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) (limited to 'src/thread/pthread_create.c') 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; -- cgit v1.2.1