Make futexes work in shared anonymous memory.

ok mpi@

diff --git a/sys/kern/sys_futex.c b/sys/kern/sys_futex.c
index c4cbe36..1cd3e71 100644 (file)
--- a/sys/kern/sys_futex.c
+++ b/sys/kern/sys_futex.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: sys_futex.c,v 1.18 2021/05/26 18:11:59 kettenis Exp $ */
+/*     $OpenBSD: sys_futex.c,v 1.19 2021/11/19 15:58:36 kettenis Exp $ */
 
 /*
  * Copyright (c) 2016-2017 Martin Pieuchot
@@ -49,6 +49,7 @@ struct futex {
        LIST_ENTRY(futex)        ft_list;       /* list of all futexes */
        TAILQ_HEAD(, proc)       ft_threads;    /* sleeping queue */
        struct uvm_object       *ft_obj;        /* UVM object */
+       struct vm_amap          *ft_amap;       /* UVM amap */
        voff_t                   ft_off;        /* UVM offset */
        unsigned int             ft_refcnt;     /* # of references */
 };
@@ -144,6 +145,7 @@ futex_get(uint32_t *uaddr, int flags)
        vm_map_t map = &p->p_vmspace->vm_map;
        vm_map_entry_t entry;
        struct uvm_object *obj = NULL;
+       struct vm_amap *amap = NULL;
        voff_t off = (vaddr_t)uaddr;
        struct futex *f;
        struct futex_list *ftlist = &p->p_p->ps_ftlist;
@@ -153,17 +155,25 @@ futex_get(uint32_t *uaddr, int flags)
        if (!(flags & FT_PRIVATE)) {
                vm_map_lock_read(map);
                if (uvm_map_lookup_entry(map, (vaddr_t)uaddr, &entry) &&
-                   UVM_ET_ISOBJ(entry) && entry->object.uvm_obj &&
                    entry->inheritance == MAP_INHERIT_SHARE) {
-                       ftlist = &ftlist_shared;
-                       obj = entry->object.uvm_obj;
-                       off = entry->offset + ((vaddr_t)uaddr - entry->start);
+                       if (UVM_ET_ISOBJ(entry)) {
+                               ftlist = &ftlist_shared;
+                               obj = entry->object.uvm_obj;
+                               off = entry->offset +
+                                   ((vaddr_t)uaddr - entry->start);
+                       } else if (entry->aref.ar_amap) {
+                               ftlist = &ftlist_shared;
+                               amap = entry->aref.ar_amap;
+                               off = ptoa(entry->aref.ar_pageoff) +
+                                   ((vaddr_t)uaddr - entry->start);
+                       }
                }
                vm_map_unlock_read(map);
        }
 
        LIST_FOREACH(f, ftlist, ft_list) {
-               if (f->ft_obj == obj && f->ft_off == off) {
+               if (f->ft_obj == obj && f->ft_amap == amap &&
+                   f->ft_off == off) {
                        f->ft_refcnt++;
                        break;
                }
@@ -177,6 +187,7 @@ futex_get(uint32_t *uaddr, int flags)
                f = pool_get(&ftpool, PR_WAITOK);
                TAILQ_INIT(&f->ft_threads);
                f->ft_obj = obj;
+               f->ft_amap = amap;
                f->ft_off = off;
                f->ft_refcnt = 1;
                LIST_INSERT_HEAD(ftlist, f, ft_list);