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Add vm_map_insert1(9)

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The function returns the newly created entry.
Use vm_map_insert1() in stack grow code to avoid gap entry re-lookup.

The comment update for vm_map_try_merge_entries() was suggested by dougm.

Suggested by:	alc
Reviewed by:	alc, markj
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D41099
This commit is contained in:
Konstantin Belousov 2023-07-19 19:44:18 +03:00
parent 3b44ee50be
commit ba41b0de3e
2 changed files with 52 additions and 25 deletions
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75
sys/vm/vm_map.c
View File

@ -1601,19 +1601,16 @@ vm_map_lookup_entry(
}
/*
* vm_map_insert:
*
* Inserts the given VM object into the target map at the
* specified address range.
*
* Requires that the map be locked, and leaves it so.
*
* If object is non-NULL, ref count must be bumped by caller
* prior to making call to account for the new entry.
* vm_map_insert1() is identical to vm_map_insert() except that it
* returns the newly inserted map entry in '*res'. In case the new
* entry is coalesced with a neighbor or an existing entry was
* resized, that entry is returned. In any case, the returned entry
* covers the specified address range.
*/
int
vm_map_insert(vm_map_t map, vm_object_t object, vm_ooffset_t offset,
vm_offset_t start, vm_offset_t end, vm_prot_t prot, vm_prot_t max, int cow)
static int
vm_map_insert1(vm_map_t map, vm_object_t object, vm_ooffset_t offset,
vm_offset_t start, vm_offset_t end, vm_prot_t prot, vm_prot_t max, int cow,
vm_map_entry_t *res)
{
vm_map_entry_t new_entry, next_entry, prev_entry;
struct ucred *cred;
@ -1760,7 +1757,8 @@ vm_map_insert(vm_map_t map, vm_object_t object, vm_ooffset_t offset,
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, next_entry);
*res = vm_map_try_merge_entries(map, prev_entry,
next_entry);
return (KERN_SUCCESS);
}
@ -1821,7 +1819,7 @@ vm_map_insert(vm_map_t map, vm_object_t object, vm_ooffset_t offset,
* other cases, which are less common.
*/
vm_map_try_merge_entries(map, prev_entry, new_entry);
vm_map_try_merge_entries(map, new_entry, next_entry);
*res = vm_map_try_merge_entries(map, new_entry, next_entry);
if ((cow & (MAP_PREFAULT | MAP_PREFAULT_PARTIAL)) != 0) {
vm_map_pmap_enter(map, start, prot, object, OFF_TO_IDX(offset),
@ -1831,6 +1829,27 @@ vm_map_insert(vm_map_t map, vm_object_t object, vm_ooffset_t offset,
return (KERN_SUCCESS);
}
/*
* vm_map_insert:
*
* Inserts the given VM object into the target map at the
* specified address range.
*
* Requires that the map be locked, and leaves it so.
*
* If object is non-NULL, ref count must be bumped by caller
* prior to making call to account for the new entry.
*/
int
vm_map_insert(vm_map_t map, vm_object_t object, vm_ooffset_t offset,
vm_offset_t start, vm_offset_t end, vm_prot_t prot, vm_prot_t max, int cow)
{
vm_map_entry_t res;
return (vm_map_insert1(map, object, offset, start, end, prot, max,
cow, &res));
}
/*
* vm_map_findspace:
*
@ -2318,13 +2337,14 @@ vm_map_merged_neighbor_dispose(vm_map_t map, vm_map_entry_t entry)
/*
* vm_map_try_merge_entries:
*
* Compare the given map entry to its predecessor, and merge its precessor
* into it if possible. The entry remains valid, and may be extended.
* The predecessor may be deleted.
* Compare two map entries that represent consecutive ranges. If
* the entries can be merged, expand the range of the second to
* cover the range of the first and delete the first. Then return
* the map entry that includes the first range.
*
* The map must be locked.
*/
void
vm_map_entry_t
vm_map_try_merge_entries(vm_map_t map, vm_map_entry_t prev_entry,
vm_map_entry_t entry)
{
@ -2334,7 +2354,9 @@ vm_map_try_merge_entries(vm_map_t map, vm_map_entry_t prev_entry,
vm_map_mergeable_neighbors(prev_entry, entry)) {
vm_map_entry_unlink(map, prev_entry, UNLINK_MERGE_NEXT);
vm_map_merged_neighbor_dispose(map, prev_entry);
return (entry);
}
return (prev_entry);
}
/*
@ -4547,10 +4569,10 @@ vm_map_stack_locked(vm_map_t map, vm_offset_t addrbos, vm_size_t max_ssize,
gap_bot = top;
gap_top = addrbos + max_ssize;
}
rv = vm_map_insert(map, NULL, 0, bot, top, prot, max, cow);
rv = vm_map_insert1(map, NULL, 0, bot, top, prot, max, cow,
&new_entry);
if (rv != KERN_SUCCESS)
return (rv);
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 ||
@ -4561,10 +4583,17 @@ vm_map_stack_locked(vm_map_t map, vm_offset_t addrbos, vm_size_t max_ssize,
("new entry lacks MAP_ENTRY_GROWS_UP"));
if (gap_bot == gap_top)
return (KERN_SUCCESS);
rv = vm_map_insert(map, NULL, 0, gap_bot, gap_top, VM_PROT_NONE,
rv = vm_map_insert1(map, NULL, 0, gap_bot, gap_top, VM_PROT_NONE,
VM_PROT_NONE, MAP_CREATE_GUARD | (orient == MAP_STACK_GROWS_DOWN ?
MAP_CREATE_STACK_GAP_DN : MAP_CREATE_STACK_GAP_UP));
MAP_CREATE_STACK_GAP_DN : MAP_CREATE_STACK_GAP_UP), &gap_entry);
if (rv == KERN_SUCCESS) {
KASSERT((gap_entry->eflags & MAP_ENTRY_GUARD) != 0,
("entry %p not gap %#x", gap_entry, gap_entry->eflags));
KASSERT((gap_entry->eflags & (MAP_ENTRY_STACK_GAP_DN |
MAP_ENTRY_STACK_GAP_UP)) != 0,
("entry %p not stack gap %#x", gap_entry,
gap_entry->eflags));
/*
* Gap can never successfully handle a fault, so
* read-ahead logic is never used for it. Re-use
@ -4574,8 +4603,6 @@ vm_map_stack_locked(vm_map_t map, vm_offset_t addrbos, vm_size_t max_ssize,
* store the original stack protections in the
* object offset.
*/
gap_entry = orient == MAP_STACK_GROWS_DOWN ?
vm_map_entry_pred(new_entry) : vm_map_entry_succ(new_entry);
gap_entry->next_read = sgp;
gap_entry->offset = prot;
} else {

2
sys/vm/vm_map.h
View File

@ -526,7 +526,7 @@ vm_map_entry_succ(vm_map_entry_t entry)
int vm_map_protect(vm_map_t map, vm_offset_t start, vm_offset_t end,
vm_prot_t new_prot, vm_prot_t new_maxprot, int flags);
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,
vm_map_entry_t vm_map_try_merge_entries(vm_map_t map, vm_map_entry_t prev,
vm_map_entry_t entry);
void vm_map_startup (void);
int vm_map_submap (vm_map_t, vm_offset_t, vm_offset_t, vm_map_t);