From 630f4cc3aa019ede55976ea561f1a7af2f068639 Mon Sep 17 00:00:00 2001 From: Szabolcs Nagy Date: Wed, 6 Dec 2017 13:05:50 +0000 Subject: [BZ #22637] Fix stack guard size accounting Previously if user requested S stack and G guard when creating a thread, the total mapping was S and the actual available stack was S - G - static_tls, which is not what the user requested. This patch fixes the guard size accounting by pretending the user requested S+G stack. This way all later logic works out except when reporting the user requested stack size (pthread_getattr_np) or when computing the minimal stack size (__pthread_get_minstack). Normally this will increase thread stack allocations by one page. TLS accounting is not affected, that will require a separate fix. [BZ #22637] * nptl/descr.h (stackblock, stackblock_size): Update comments. * nptl/allocatestack.c (allocate_stack): Add guardsize to stacksize. * nptl/nptl-init.c (__pthread_get_minstack): Remove guardsize from stacksize. * nptl/pthread_getattr_np.c (pthread_getattr_np): Likewise. --- nptl/pthread_getattr_np.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'nptl/pthread_getattr_np.c') diff --git a/nptl/pthread_getattr_np.c b/nptl/pthread_getattr_np.c index 961d711..ae12592 100644 --- a/nptl/pthread_getattr_np.c +++ b/nptl/pthread_getattr_np.c @@ -57,9 +57,12 @@ pthread_getattr_np (pthread_t thread_id, pthread_attr_t *attr) /* The sizes are subject to alignment. */ if (__glibc_likely (thread->stackblock != NULL)) { - iattr->stacksize = thread->stackblock_size; + /* The stack size reported to the user should not include the + guard size. */ + iattr->stacksize = thread->stackblock_size - thread->guardsize; #if _STACK_GROWS_DOWN - iattr->stackaddr = (char *) thread->stackblock + iattr->stacksize; + iattr->stackaddr = (char *) thread->stackblock + + thread->stackblock_size; #else iattr->stackaddr = (char *) thread->stackblock; #endif -- cgit v1.1