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TLS (GNU/C11 thread-local storage) support for static-linked programs

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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.
This commit is contained in:
Rich Felker
2012-10-04 16:35:46 -04:00
parent adefe830dd
commit 8431d7972f
6 changed files with 117 additions and 14 deletions
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24
src/thread/pthread_self.c
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@ -1,6 +1,6 @@
#include "pthread_impl.h"
static struct pthread main_thread;
static struct pthread *main_thread = &(struct pthread){0};
/* pthread_key_create.c overrides this */
static const void *dummy[1] = { 0 };
@ -10,14 +10,14 @@ static int init_main_thread()
{
__syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
SIGPT_SET, 0, __SYSCALL_SSLEN);
if (__set_thread_area(&main_thread) < 0) return -1;
main_thread.canceldisable = libc.canceldisable;
main_thread.tsd = (void **)__pthread_tsd_main;
main_thread.errno_ptr = __errno_location();
main_thread.self = &main_thread;
main_thread.tid = main_thread.pid =
__syscall(SYS_set_tid_address, &main_thread.tid);
libc.main_thread = &main_thread;
if (__set_thread_area(main_thread) < 0) return -1;
main_thread->canceldisable = libc.canceldisable;
main_thread->tsd = (void **)__pthread_tsd_main;
main_thread->errno_ptr = __errno_location();
main_thread->self = main_thread;
main_thread->tid = main_thread->pid =
__syscall(SYS_set_tid_address, &main_thread->tid);
libc.main_thread = main_thread;
return 0;
}
@ -35,3 +35,9 @@ pthread_t __pthread_self_def()
weak_alias(__pthread_self_def, pthread_self);
weak_alias(__pthread_self_def, __pthread_self_init);
void *__install_initial_tls(void *p)
{
main_thread = p;
return __pthread_self_def();
}