Author: dougm
Date: Wed Nov 13 15:56:07 2019
New Revision: 354684
URL: https://svnweb.freebsd.org/changeset/base/354684

Log:
  Define wrapper functions vm_map_entry_{succ,pred} to act as wrappers
  around entry->{next,prev} when those are used for ordered list
  traversal, and use those wrapper functions everywhere. Where the next
  field is used for maintaining a stack of deferred operations, #define
  defer_next to make that different usage clearer, and then use the
  'right' pointer instead of 'next' for that purpose.
  
  Approved by: markj
  Tested by: pho (as part of a larger patch)
  Differential Revision: https://reviews.freebsd.org/D22347

Modified:
  head/sys/security/mac/mac_process.c
  head/sys/vm/vm_map.c
  head/sys/vm/vm_map.h
  head/sys/vm/vm_mmap.c

Modified: head/sys/security/mac/mac_process.c
==============================================================================
--- head/sys/security/mac/mac_process.c Wed Nov 13 15:31:31 2019        
(r354683)
+++ head/sys/security/mac/mac_process.c Wed Nov 13 15:56:07 2019        
(r354684)
@@ -363,7 +363,8 @@ mac_proc_vm_revoke_recurse(struct thread *td, struct u
                        }
                        pmap_protect(map->pmap, vme->start, vme->end,
                            vme->protection & ~revokeperms);
-                       vm_map_try_merge_entries(map, vme->prev, vme);
+                       vm_map_try_merge_entries(map, vm_map_entry_pred(vme),
+                           vme);
                }
        }
        vm_map_unlock(map);

Modified: head/sys/vm/vm_map.c
==============================================================================
--- head/sys/vm/vm_map.c        Wed Nov 13 15:31:31 2019        (r354683)
+++ head/sys/vm/vm_map.c        Wed Nov 13 15:56:07 2019        (r354684)
@@ -563,6 +563,12 @@ vm_map_entry_set_vnode_text(vm_map_entry_t entry, bool
        }
 }
 
+/*
+ * Use a different name for this vm_map_entry field when it's use
+ * is not consistent with its use as part of an ordered search tree.
+ */
+#define defer_next right
+
 static void
 vm_map_process_deferred(void)
 {
@@ -574,7 +580,7 @@ vm_map_process_deferred(void)
        entry = td->td_map_def_user;
        td->td_map_def_user = NULL;
        while (entry != NULL) {
-               next = entry->next;
+               next = entry->defer_next;
                MPASS((entry->eflags & (MAP_ENTRY_WRITECNT |
                    MAP_ENTRY_VN_EXEC)) != (MAP_ENTRY_WRITECNT |
                    MAP_ENTRY_VN_EXEC));
@@ -1436,7 +1442,7 @@ vm_map_insert(vm_map_t map, vm_object_t object, vm_oof
        /*
         * Assert that the next entry doesn't overlap the end point.
         */
-       if (prev_entry->next->start < end)
+       if (vm_map_entry_succ(prev_entry)->start < end)
                return (KERN_NO_SPACE);
 
        if ((cow & MAP_CREATE_GUARD) != 0 && (object != NULL ||
@@ -1529,7 +1535,8 @@ charged:
                                map->size += end - prev_entry->end;
                        vm_map_entry_resize(map, prev_entry,
                            end - prev_entry->end);
-                       vm_map_try_merge_entries(map, prev_entry, 
prev_entry->next);
+                       vm_map_try_merge_entries(map, prev_entry,
+                           vm_map_entry_succ(prev_entry));
                        return (KERN_SUCCESS);
                }
 
@@ -1590,7 +1597,7 @@ charged:
         * other cases, which are less common.
         */
        vm_map_try_merge_entries(map, prev_entry, new_entry);
-       vm_map_try_merge_entries(map, new_entry, new_entry->next);
+       vm_map_try_merge_entries(map, new_entry, vm_map_entry_succ(new_entry));
 
        if ((cow & (MAP_PREFAULT | MAP_PREFAULT_PARTIAL)) != 0) {
                vm_map_pmap_enter(map, start, prot, object, OFF_TO_IDX(offset),
@@ -2288,7 +2295,7 @@ vm_map_submap(
        if (vm_map_lookup_entry(map, start, &entry)) {
                vm_map_clip_start(map, entry, start);
        } else
-               entry = entry->next;
+               entry = vm_map_entry_succ(entry);
 
        vm_map_clip_end(map, entry, end);
 
@@ -2445,12 +2452,13 @@ again:
        VM_MAP_RANGE_CHECK(map, start, end);
 
        if (!vm_map_lookup_entry(map, start, &entry))
-               entry = entry->next;
+               entry = vm_map_entry_succ(entry);
 
        /*
         * Make a first pass to check for protection violations.
         */
-       for (current = entry; current->start < end; current = current->next) {
+       for (current = entry; current->start < end;
+           current = vm_map_entry_succ(current)) {
                if ((current->eflags & MAP_ENTRY_GUARD) != 0)
                        continue;
                if (current->eflags & MAP_ENTRY_IS_SUB_MAP) {
@@ -2488,7 +2496,8 @@ again:
         */
        rv = KERN_SUCCESS;
        vm_map_clip_start(map, entry, start);
-       for (current = entry; current->start < end; current = current->next) {
+       for (current = entry; current->start < end;
+           current = vm_map_entry_succ(current)) {
 
                vm_map_clip_end(map, current, end);
 
@@ -2546,8 +2555,8 @@ again:
         * [Note that clipping is not necessary the second time.]
         */
        for (current = entry; current->start < end;
-           vm_map_try_merge_entries(map, current->prev, current),
-           current = current->next) {
+            vm_map_try_merge_entries(map, vm_map_entry_pred(current), current),
+           current = vm_map_entry_succ(current)) {
                if (rv != KERN_SUCCESS ||
                    (current->eflags & MAP_ENTRY_GUARD) != 0)
                        continue;
@@ -2585,7 +2594,7 @@ again:
 #undef MASK
                }
        }
-       vm_map_try_merge_entries(map, current->prev, current);
+       vm_map_try_merge_entries(map, vm_map_entry_pred(current), current);
        vm_map_unlock(map);
        return (rv);
 }
@@ -2648,7 +2657,7 @@ vm_map_madvise(
                if (modify_map)
                        vm_map_clip_start(map, entry, start);
        } else {
-               entry = entry->next;
+               entry = vm_map_entry_succ(entry);
        }
 
        if (modify_map) {
@@ -2659,7 +2668,7 @@ vm_map_madvise(
                 * limited to the specified address range.
                 */
                for (current = entry; current->start < end;
-                   current = current->next) {
+                   current = vm_map_entry_succ(current)) {
                        if (current->eflags & MAP_ENTRY_IS_SUB_MAP)
                                continue;
 
@@ -2690,9 +2699,11 @@ vm_map_madvise(
                        default:
                                break;
                        }
-                       vm_map_try_merge_entries(map, current->prev, current);
+                       vm_map_try_merge_entries(map,
+                           vm_map_entry_pred(current), current);
                }
-               vm_map_try_merge_entries(map, current->prev, current);
+               vm_map_try_merge_entries(map, vm_map_entry_pred(current),
+                   current);
                vm_map_unlock(map);
        } else {
                vm_pindex_t pstart, pend;
@@ -2705,7 +2716,7 @@ vm_map_madvise(
                 * the vm_object pindex and count.
                 */
                for (current = entry; current->start < end;
-                   current = current->next) {
+                   current = vm_map_entry_succ(current)) {
                        vm_offset_t useEnd, useStart;
 
                        if (current->eflags & MAP_ENTRY_IS_SUB_MAP)
@@ -2812,16 +2823,16 @@ vm_map_inherit(vm_map_t map, vm_offset_t start, vm_off
                entry = temp_entry;
                vm_map_clip_start(map, entry, start);
        } else
-               entry = temp_entry->next;
+               entry = vm_map_entry_succ(temp_entry);
        while (entry->start < end) {
                vm_map_clip_end(map, entry, end);
                if ((entry->eflags & MAP_ENTRY_GUARD) == 0 ||
                    new_inheritance != VM_INHERIT_ZERO)
                        entry->inheritance = new_inheritance;
-               vm_map_try_merge_entries(map, entry->prev, entry);
-               entry = entry->next;
+               vm_map_try_merge_entries(map, vm_map_entry_pred(entry), entry);
+               entry = vm_map_entry_succ(entry);
        }
-       vm_map_try_merge_entries(map, entry->prev, entry);
+       vm_map_try_merge_entries(map, vm_map_entry_pred(entry), entry);
        vm_map_unlock(map);
        return (KERN_SUCCESS);
 }
@@ -2870,7 +2881,7 @@ vm_map_entry_in_transition(vm_map_t map, vm_offset_t i
                        *io_end = start;
                        return (NULL);
                }
-               entry = entry->next;
+               entry = vm_map_entry_succ(entry);
        }
        return (entry);
 }
@@ -2896,7 +2907,7 @@ vm_map_unwire(vm_map_t map, vm_offset_t start, vm_offs
        VM_MAP_RANGE_CHECK(map, start, end);
        if (!vm_map_lookup_entry(map, start, &first_entry)) {
                if (holes_ok)
-                       first_entry = first_entry->next;
+                       first_entry = vm_map_entry_succ(first_entry);
                else {
                        vm_map_unlock(map);
                        return (KERN_INVALID_ADDRESS);
@@ -2940,7 +2951,8 @@ vm_map_unwire(vm_map_t map, vm_offset_t start, vm_offs
                 * If holes_ok, skip this check.
                 */
                if (!holes_ok &&
-                   (entry->end < end && entry->next->start > entry->end)) {
+                   (entry->end < end &&
+                   vm_map_entry_succ(entry)->start > entry->end)) {
                        end = entry->end;
                        rv = KERN_INVALID_ADDRESS;
                        break;
@@ -2954,15 +2966,16 @@ vm_map_unwire(vm_map_t map, vm_offset_t start, vm_offs
                        rv = KERN_INVALID_ARGUMENT;
                        break;
                }
-               entry = entry->next;
+               entry = vm_map_entry_succ(entry);
        }
        need_wakeup = false;
        if (first_entry == NULL &&
            !vm_map_lookup_entry(map, start, &first_entry)) {
                KASSERT(holes_ok, ("vm_map_unwire: lookup failed"));
-               first_entry = first_entry->next;
+               first_entry = vm_map_entry_succ(first_entry);
        }
-       for (entry = first_entry; entry->start < end; entry = entry->next) {
+       for (entry = first_entry; entry->start < end;
+           entry = vm_map_entry_succ(entry)) {
                /*
                 * If holes_ok was specified, an empty
                 * space in the unwired region could have been mapped
@@ -2998,9 +3011,9 @@ vm_map_unwire(vm_map_t map, vm_offset_t start, vm_offs
                        entry->eflags &= ~MAP_ENTRY_NEEDS_WAKEUP;
                        need_wakeup = true;
                }
-               vm_map_try_merge_entries(map, entry->prev, entry);
+               vm_map_try_merge_entries(map, vm_map_entry_pred(entry), entry);
        }
-       vm_map_try_merge_entries(map, entry->prev, entry);
+       vm_map_try_merge_entries(map, vm_map_entry_pred(entry), entry);
        vm_map_unlock(map);
        if (need_wakeup)
                vm_map_wakeup(map);
@@ -3106,7 +3119,7 @@ vm_map_wire_locked(vm_map_t map, vm_offset_t start, vm
        VM_MAP_RANGE_CHECK(map, start, end);
        if (!vm_map_lookup_entry(map, start, &first_entry)) {
                if (holes_ok)
-                       first_entry = first_entry->next;
+                       first_entry = vm_map_entry_succ(first_entry);
                else
                        return (KERN_INVALID_ADDRESS);
        }
@@ -3210,7 +3223,7 @@ vm_map_wire_locked(vm_map_t map, vm_offset_t start, vm
                                            faddr < entry->end)
                                                vm_map_wire_entry_failure(map,
                                                    entry, faddr);
-                                       entry = entry->next;
+                                       entry = vm_map_entry_succ(entry);
                                }
                        }
                        if (rv != KERN_SUCCESS) {
@@ -3229,12 +3242,13 @@ vm_map_wire_locked(vm_map_t map, vm_offset_t start, vm
                 * If holes_ok was specified, skip this check.
                 */
                if (!holes_ok &&
-                   entry->end < end && entry->next->start > entry->end) {
+                   entry->end < end &&
+                   vm_map_entry_succ(entry)->start > entry->end) {
                        end = entry->end;
                        rv = KERN_INVALID_ADDRESS;
                        goto done;
                }
-               entry = entry->next;
+               entry = vm_map_entry_succ(entry);
        }
        rv = KERN_SUCCESS;
 done:
@@ -3242,9 +3256,10 @@ done:
        if (first_entry == NULL &&
            !vm_map_lookup_entry(map, start, &first_entry)) {
                KASSERT(holes_ok, ("vm_map_wire: lookup failed"));
-               first_entry = first_entry->next;
+               first_entry = vm_map_entry_succ(first_entry);
        }
-       for (entry = first_entry; entry->start < end; entry = entry->next) {
+       for (entry = first_entry; entry->start < end;
+           entry = vm_map_entry_succ(entry)) {
                /*
                 * If holes_ok was specified, an empty
                 * space in the unwired region could have been mapped
@@ -3297,9 +3312,9 @@ done:
                        entry->eflags &= ~MAP_ENTRY_NEEDS_WAKEUP;
                        need_wakeup = true;
                }
-               vm_map_try_merge_entries(map, entry->prev, entry);
+               vm_map_try_merge_entries(map, vm_map_entry_pred(entry), entry);
        }
-       vm_map_try_merge_entries(map, entry->prev, entry);
+       vm_map_try_merge_entries(map, vm_map_entry_pred(entry), entry);
        if (need_wakeup)
                vm_map_wakeup(map);
        return (rv);
@@ -3349,13 +3364,14 @@ vm_map_sync(
        /*
         * Make a first pass to check for user-wired memory and holes.
         */
-       for (current = entry; current->start < end; current = current->next) {
+       for (current = entry; current->start < end;
+           current = vm_map_entry_succ(current)) {
                if (invalidate && (current->eflags & MAP_ENTRY_USER_WIRED)) {
                        vm_map_unlock_read(map);
                        return (KERN_INVALID_ARGUMENT);
                }
                if (end > current->end &&
-                   current->end != current->next->start) {
+                   current->end != vm_map_entry_succ(current)->start) {
                        vm_map_unlock_read(map);
                        return (KERN_INVALID_ADDRESS);
                }
@@ -3399,7 +3415,7 @@ vm_map_sync(
                vm_map_lock_read(map);
                if (last_timestamp == map->timestamp ||
                    !vm_map_lookup_entry(map, start, &current))
-                       current = current->next;
+                       current = vm_map_entry_succ(current);
        }
 
        vm_map_unlock_read(map);
@@ -3517,7 +3533,7 @@ vm_map_entry_delete(vm_map_t map, vm_map_entry_t entry
        if (map->system_map)
                vm_map_entry_deallocate(entry, TRUE);
        else {
-               entry->next = curthread->td_map_def_user;
+               entry->defer_next = curthread->td_map_def_user;
                curthread->td_map_def_user = entry;
        }
 }
@@ -3542,7 +3558,7 @@ vm_map_delete(vm_map_t map, vm_offset_t start, vm_offs
         * Find the start of the region, and clip it
         */
        if (!vm_map_lookup_entry(map, start, &first_entry))
-               entry = first_entry->next;
+               entry = vm_map_entry_succ(first_entry);
        else {
                entry = first_entry;
                vm_map_clip_start(map, entry, start);
@@ -3580,7 +3596,7 @@ vm_map_delete(vm_map_t map, vm_offset_t start, vm_offs
                                 */
                                if (!vm_map_lookup_entry(map, saved_start,
                                                         &tmp_entry))
-                                       entry = tmp_entry->next;
+                                       entry = vm_map_entry_succ(tmp_entry);
                                else {
                                        entry = tmp_entry;
                                        vm_map_clip_start(map, entry,
@@ -3591,7 +3607,7 @@ vm_map_delete(vm_map_t map, vm_offset_t start, vm_offs
                }
                vm_map_clip_end(map, entry, end);
 
-               next = entry->next;
+               next = vm_map_entry_succ(entry);
 
                /*
                 * Unwire before removing addresses from the pmap; otherwise,
@@ -3680,7 +3696,7 @@ vm_map_check_protection(vm_map_t map, vm_offset_t star
                        return (FALSE);
                /* go to next entry */
                start = entry->end;
-               entry = entry->next;
+               entry = vm_map_entry_succ(entry);
        }
        return (TRUE);
 }
@@ -3789,7 +3805,8 @@ vm_map_copy_entry(
                                fake_entry->object.vm_object = src_object;
                                fake_entry->start = src_entry->start;
                                fake_entry->end = src_entry->end;
-                               fake_entry->next = curthread->td_map_def_user;
+                               fake_entry->defer_next =
+                                   curthread->td_map_def_user;
                                curthread->td_map_def_user = fake_entry;
                        }
 
@@ -4049,7 +4066,7 @@ vmspace_fork(struct vmspace *vm1, vm_ooffset_t *fork_c
 
                        break;
                }
-               old_entry = old_entry->next;
+               old_entry = vm_map_entry_succ(old_entry);
        }
        /*
         * Use inlined vm_map_unlock() to postpone handling the deferred
@@ -4136,7 +4153,7 @@ vm_map_stack_locked(vm_map_t map, vm_offset_t addrbos,
        /*
         * If we can't accommodate max_ssize in the current mapping, no go.
         */
-       if (prev_entry->next->start < addrbos + max_ssize)
+       if (vm_map_entry_succ(prev_entry)->start < addrbos + max_ssize)
                return (KERN_NO_SPACE);
 
        /*
@@ -4163,7 +4180,7 @@ vm_map_stack_locked(vm_map_t map, vm_offset_t addrbos,
        rv = vm_map_insert(map, NULL, 0, bot, top, prot, max, cow);
        if (rv != KERN_SUCCESS)
                return (rv);
-       new_entry = prev_entry->next;
+       new_entry = vm_map_entry_succ(prev_entry);
        KASSERT(new_entry->end == top || new_entry->start == bot,
            ("Bad entry start/end for new stack entry"));
        KASSERT((orient & MAP_STACK_GROWS_DOWN) == 0 ||
@@ -4185,9 +4202,9 @@ vm_map_stack_locked(vm_map_t map, vm_offset_t addrbos,
                 * stack_guard_page for vm_map_growstack().
                 */
                if (orient == MAP_STACK_GROWS_DOWN)
-                       new_entry->prev->next_read = sgp;
+                       vm_map_entry_pred(new_entry)->next_read = sgp;
                else
-                       new_entry->next->next_read = sgp;
+                       vm_map_entry_succ(new_entry)->next_read = sgp;
        } else {
                (void)vm_map_delete(map, bot, top);
        }
@@ -4241,14 +4258,14 @@ retry:
        if ((gap_entry->eflags & MAP_ENTRY_GUARD) == 0)
                return (KERN_SUCCESS);
        if ((gap_entry->eflags & MAP_ENTRY_STACK_GAP_DN) != 0) {
-               stack_entry = gap_entry->next;
+               stack_entry = vm_map_entry_succ(gap_entry);
                if ((stack_entry->eflags & MAP_ENTRY_GROWS_DOWN) == 0 ||
                    stack_entry->start != gap_entry->end)
                        return (KERN_FAILURE);
                grow_amount = round_page(stack_entry->start - addr);
                grow_down = true;
        } else if ((gap_entry->eflags & MAP_ENTRY_STACK_GAP_UP) != 0) {
-               stack_entry = gap_entry->prev;
+               stack_entry = vm_map_entry_pred(gap_entry);
                if ((stack_entry->eflags & MAP_ENTRY_GROWS_UP) == 0 ||
                    stack_entry->end != gap_entry->start)
                        return (KERN_FAILURE);
@@ -4826,9 +4843,10 @@ _vm_map_assert_consistent(vm_map_t map, int check)
                KASSERT(entry->start < entry->end,
                    ("map %p start = %jx, end = %jx", map,
                    (uintmax_t)entry->start, (uintmax_t)entry->end));
-               KASSERT(entry->end <= entry->next->start,
+               KASSERT(entry->end <= vm_map_entry_succ(entry)->start,
                    ("map %p end = %jx, next->start = %jx", map,
-                   (uintmax_t)entry->end, (uintmax_t)entry->next->start));
+                    (uintmax_t)entry->end,
+                    (uintmax_t)vm_map_entry_succ(entry)->start));
                KASSERT(entry->left == NULL ||
                    entry->left->start < entry->start,
                    ("map %p left->start = %jx, start = %jx", map,
@@ -4837,14 +4855,16 @@ _vm_map_assert_consistent(vm_map_t map, int check)
                    entry->start < entry->right->start,
                    ("map %p start = %jx, right->start = %jx", map,
                    (uintmax_t)entry->start, (uintmax_t)entry->right->start));
-               max_left = vm_map_entry_max_free_left(entry, entry->prev);
-               max_right = vm_map_entry_max_free_right(entry, entry->next);
+               max_left = vm_map_entry_max_free_left(entry,
+                   vm_map_entry_pred(entry));
+               max_right = vm_map_entry_max_free_right(entry,
+                   vm_map_entry_succ(entry));
                KASSERT(entry->max_free == MAX(max_left, max_right),
                    ("map %p max = %jx, max_left = %jx, max_right = %jx", map,
                    (uintmax_t)entry->max_free,
                    (uintmax_t)max_left, (uintmax_t)max_right));
                prev = entry;
-       }       
+       }
        KASSERT(prev->end <= entry->start,
            ("map %p prev->end = %jx, start = %jx", map,
            (uintmax_t)prev->end, (uintmax_t)entry->start));

Modified: head/sys/vm/vm_map.h
==============================================================================
--- head/sys/vm/vm_map.h        Wed Nov 13 15:31:31 2019        (r354683)
+++ head/sys/vm/vm_map.h        Wed Nov 13 15:56:07 2019        (r354684)
@@ -419,10 +419,25 @@ int vm_map_lookup_locked(vm_map_t *, vm_offset_t, vm_p
     vm_pindex_t *, vm_prot_t *, boolean_t *);
 void vm_map_lookup_done (vm_map_t, vm_map_entry_t);
 boolean_t vm_map_lookup_entry (vm_map_t, vm_offset_t, vm_map_entry_t *);
+
+static inline vm_map_entry_t
+vm_map_entry_succ(vm_map_entry_t entry)
+{
+
+       return (entry->next);
+}
+
+static inline vm_map_entry_t
+vm_map_entry_pred(vm_map_entry_t entry)
+{
+
+       return (entry->prev);
+}
+
 #define VM_MAP_ENTRY_FOREACH(it, map)                  \
        for ((it) = (map)->header.next;         \
            (it) != &(map)->header;             \
-           (it) = (it)->next)
+           (it) = vm_map_entry_succ(it))
 int vm_map_protect (vm_map_t, vm_offset_t, vm_offset_t, vm_prot_t, boolean_t);
 int vm_map_remove (vm_map_t, vm_offset_t, vm_offset_t);
 void vm_map_try_merge_entries(vm_map_t map, vm_map_entry_t prev,

Modified: head/sys/vm/vm_mmap.c
==============================================================================
--- head/sys/vm/vm_mmap.c       Wed Nov 13 15:31:31 2019        (r354683)
+++ head/sys/vm/vm_mmap.c       Wed Nov 13 15:56:07 2019        (r354684)
@@ -581,7 +581,7 @@ kern_munmap(struct thread *td, uintptr_t addr0, size_t
                pkm.pm_address = (uintptr_t) NULL;
                if (vm_map_lookup_entry(map, addr, &entry)) {
                        for (; entry->start < addr + size;
-                           entry = entry->next) {
+                           entry = vm_map_entry_succ(entry)) {
                                if (vm_map_check_protection(map, entry->start,
                                        entry->end, VM_PROT_EXECUTE) == TRUE) {
                                        pkm.pm_address = (uintptr_t) addr;
@@ -817,12 +817,15 @@ RestartScan:
         * up the pages elsewhere.
         */
        lastvecindex = -1;
-       for (current = entry; current->start < end; current = current->next) {
+       while (entry->start < end) {
 
                /*
                 * check for contiguity
                 */
-               if (current->end < end && current->next->start > current->end) {
+               current = entry;
+               entry = vm_map_entry_succ(current);
+               if (current->end < end &&
+                   entry->start > current->end) {
                        vm_map_unlock_read(map);
                        return (ENOMEM);
                }
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