From 0bb27b81a762d3c607bd25409337c749f836c0cd Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Wed, 20 Jan 2021 22:09:22 +0100 Subject: [PATCH] libgomp: Fix up GOMP_task on s390x On Wed, Jan 20, 2021 at 05:04:39PM +0100, Florian Weimer wrote: > Sorry, this appears to cause OpenMP task state corruption in RPM. We > have only seen this on s390x. Haven't actually verified it, but my suspection is that this is a caller stack corruption. We play with fire with the GOMP_task API/ABI extensions, the GOMP_task function used to be: void GOMP_task (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *), long arg_size, long arg_align, bool if_clause, unsigned flags); and later: void GOMP_task (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *), long arg_size, long arg_align, bool if_clause, unsigned flags, void **depend); and later: void GOMP_task (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *), long arg_size, long arg_align, bool if_clause, unsigned flags, void **depend, int priority); and now: void GOMP_task (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *), long arg_size, long arg_align, bool if_clause, unsigned flags, void **depend, int priority, void *detach) and which of those depend, priority and detach argument is present depends on the bits in flags. I'm afraid the compiler just decided to spill the detach = NULL store in if ((flags & GOMP_TASK_FLAG_DETACH) == 0) detach = NULL; on s390x into the argument stack slot. Not a problem if the caller passes all those 10 arguments, but if not, can clobber random stack location. This hack should fix it up. Priority doesn't need changing, but I've changed it anyway just to be safe. With the patch none of the 3 arguments are ever modified, so I'd hope gcc doesn't decide to spill something unrelated there. 2021-01-20 Jakub Jelinek * task.c (GOMP_task): Rename priority argument to priority_arg, add priority automatic variable and modify that variable. Instead of clearing detach argument when GOMP_TASK_FLAG_DETACH bit is not set, check flags for that bit. --- libgomp/task.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/libgomp/task.c b/libgomp/task.c index 8db031cc052..b242e7c8d20 100644 --- a/libgomp/task.c +++ b/libgomp/task.c @@ -354,10 +354,11 @@ task_fulfilled_p (struct gomp_task *task) void GOMP_task (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *), long arg_size, long arg_align, bool if_clause, unsigned flags, - void **depend, int priority, void *detach) + void **depend, int priority_arg, void *detach) { struct gomp_thread *thr = gomp_thread (); struct gomp_team *team = thr->ts.team; + int priority = 0; #ifdef HAVE_BROKEN_POSIX_SEMAPHORES /* If pthread_mutex_* is used for omp_*lock*, then each task must be @@ -385,13 +386,12 @@ GOMP_task (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *), } } - if ((flags & GOMP_TASK_FLAG_PRIORITY) == 0) - priority = 0; - else if (priority > gomp_max_task_priority_var) - priority = gomp_max_task_priority_var; - - if ((flags & GOMP_TASK_FLAG_DETACH) == 0) - detach = NULL; + if (__builtin_expect ((flags & GOMP_TASK_FLAG_PRIORITY) != 0, 0)) + { + priority = priority_arg; + if (priority > gomp_max_task_priority_var) + priority = gomp_max_task_priority_var; + } if (!if_clause || team == NULL || (thr->task && thr->task->final_task) @@ -415,7 +415,7 @@ GOMP_task (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *), || (flags & GOMP_TASK_FLAG_FINAL); task.priority = priority; - if (detach) + if ((flags & GOMP_TASK_FLAG_DETACH) != 0) { task.detach = true; gomp_sem_init (&task.completion_sem, 0); @@ -443,7 +443,7 @@ GOMP_task (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *), else fn (data); - if (detach && !task_fulfilled_p (&task)) + if (task.detach && !task_fulfilled_p (&task)) gomp_sem_wait (&task.completion_sem); /* Access to "children" is normally done inside a task_lock @@ -484,7 +484,7 @@ GOMP_task (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *), task->kind = GOMP_TASK_UNDEFERRED; task->in_tied_task = parent->in_tied_task; task->taskgroup = taskgroup; - if (detach) + if ((flags & GOMP_TASK_FLAG_DETACH) != 0) { task->detach = true; gomp_sem_init (&task->completion_sem, 0); -- 2.30.2