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vmm: switch out old vmmrange allocator for a slab object cache

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This commit is contained in:
Matheus
2026-04-22 19:47:05 -03:00
parent e297e6d3ae
commit b7b8e3c66d
2 changed files with 16 additions and 93 deletions
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kernel-src/include/kernel/vmm.h
-14
View File
@@ -41,20 +41,6 @@ typedef struct vmmrange_t{
};
} vmmrange_t;
typedef struct {
mutex_t lock;
struct vmmcache_t *next;
size_t freecount;
uintmax_t firstfree;
} vmmcacheheader_t;
#define VMM_RANGES_PER_CACHE (PAGE_SIZE - sizeof(vmmcacheheader_t)) / sizeof(vmmrange_t)
typedef struct vmmcache_t {
vmmcacheheader_t header;
vmmrange_t ranges[VMM_RANGES_PER_CACHE];
} vmmcache_t;
typedef struct {
mutex_t lock;
rbtree_t *ranges;
kernel-src/mm/vmm.c
+16 -79
View File
@@ -11,70 +11,7 @@
#define RANGE_TOP(x) (void *)((uintptr_t)x->start + x->size)
static vmmcache_t *newcache() {
vmmcache_t *ptr = pmm_allocpage(PMM_SECTION_DEFAULT);
if (ptr == NULL)
return NULL;
ptr = MAKE_HHDM(ptr);
ptr->header.freecount = VMM_RANGES_PER_CACHE;
ptr->header.firstfree = 0;
ptr->header.next = NULL;
MUTEX_INIT(&ptr->header.lock);
for (uintmax_t i = 0; i < VMM_RANGES_PER_CACHE; ++i)
ptr->ranges[i].size = 0;
return ptr;
}
// entries are allocated directly from the pmm into these caches
static vmmcache_t *cachelist;
// only supposed to be called on locked, not fully used caches
static uintmax_t getentrynumber(vmmcache_t *cache) {
for (uintmax_t i = cache->header.firstfree; i < VMM_RANGES_PER_CACHE; ++i) {
if (cache->ranges[i].size == 0)
return i;
}
__assert(!"get entry number called from full cache");
}
static vmmrange_t *allocrange() {
vmmcache_t *cache = cachelist;
vmmrange_t *range = NULL;
while (cache) {
MUTEX_ACQUIRE(&cache->header.lock);
if (cache->header.freecount > 0) {
--cache->header.freecount;
uintmax_t r = getentrynumber(cache);
cache->header.firstfree = r + 1;
range = &cache->ranges[r];
range->size = -1; // set as allocated temporarily
MUTEX_RELEASE(&cache->header.lock);
break;
} else if (cache->header.next == NULL)
cache->header.next = newcache();
vmmcache_t *next = cache->header.next;
MUTEX_RELEASE(&cache->header.lock);
cache = next;
}
return range;
}
static void freerange(vmmrange_t *range) {
vmmcache_t *cache = (vmmcache_t *)ROUND_DOWN((uintptr_t)range, PAGE_SIZE);
MUTEX_ACQUIRE(&cache->header.lock);
int rangeoffset = ((uintptr_t)range - (uintptr_t)cache->ranges) / sizeof(vmmrange_t);
range->size = 0;
++cache->header.freecount;
if (cache->header.firstfree > rangeoffset)
cache->header.firstfree = rangeoffset;
MUTEX_RELEASE(&cache->header.lock);
}
static scache_t *range_cache;
// ranges are separated into kernel and user. the kernel has a temporary user context
vmmcontext_t vmm_kernelctx;
@@ -195,7 +132,7 @@ static void insertrange(vmmspace_t *space, vmmrange_t *new_range) {
new_range->size += next_range->size;
rbtree_remove(&space->ranges, &next_range->rbtree_node);
freerange(next_range);
slab_free(range_cache, next_range);
if (new_range->flags & VMM_FLAGS_FILE) {
VOP_RELEASE(new_range->vnode);
}
@@ -206,7 +143,7 @@ static void insertrange(vmmspace_t *space, vmmrange_t *new_range) {
prev_range->size += new_range->size;
rbtree_remove(&space->ranges, &new_range->rbtree_node);
freerange(new_range);
slab_free(range_cache, new_range);
if (prev_range->flags & VMM_FLAGS_FILE) {
VOP_RELEASE(prev_range->vnode);
}
@@ -313,7 +250,7 @@ static int changemap(vmmspace_t *space, void *address, size_t size, bool free, i
// allocated here and as soon as its used to make sure that
// even in an allocation failure there will always be a valid mapping
if (free == false) {
new_range = allocrange();
new_range = slab_allocate(range_cache);
if (new_range == NULL)
return ENOMEM;
}
@@ -350,7 +287,7 @@ static int changemap(vmmspace_t *space, void *address, size_t size, bool free, i
goto leave;
}
vmmrange_t *new = allocrange();
vmmrange_t *new = slab_allocate(range_cache);
if (range == NULL) {
error = ENOMEM;
goto leave;
@@ -433,7 +370,7 @@ static int changemap(vmmspace_t *space, void *address, size_t size, bool free, i
rbtree = rbtree_successor(&new_range->rbtree_node);
new_range = allocrange();
new_range = slab_allocate(range_cache);
if (new_range == NULL) {
error = ENOMEM;
goto leave;
@@ -456,7 +393,7 @@ static int changemap(vmmspace_t *space, void *address, size_t size, bool free, i
if (free) {
rbtree_remove(&space->ranges, &range->rbtree_node);
destroyrange(range, 0, range->size, 0);
freerange(range);
slab_free(range_cache, range);
} else {
// permission check
if ((flags & VMM_FLAGS_CREDCHECK) && (range->flags & VMM_FLAGS_SHARED) &&
@@ -513,7 +450,7 @@ static int changemap(vmmspace_t *space, void *address, size_t size, bool free, i
leave:
if (free == false)
freerange(new_range);
slab_free(range_cache, new_range);
return error;
}
@@ -804,7 +741,7 @@ void *vmm_map(void *addr, volatile size_t size, int flags, mmuflags_t mmuflags,
if (((flags & VMM_FLAGS_EXACT) && start != addr) || start == NULL)
goto cleanup;
range = allocrange();
range = slab_allocate(range_cache);
if (range == NULL)
goto cleanup;
@@ -882,8 +819,8 @@ void *vmm_map(void *addr, volatile size_t size, int flags, mmuflags_t mmuflags,
insertrange(space, range);
cleanup:
if (start == NULL && range)
freerange(range);
if (retaddr == NULL && range)
slab_free(range_cache, range);
MUTEX_RELEASE(&space->lock);
return retaddr;
@@ -967,7 +904,7 @@ vmmcontext_t *vmm_fork(vmmcontext_t *oldcontext) {
rbtree_t *rbtree = oldcontext->space.ranges ? rbtree_first(oldcontext->space.ranges) : NULL;
while (rbtree) {
vmmrange_t *range = container_of(rbtree, vmmrange_t, rbtree_node);
vmmrange_t *newrange = allocrange();
vmmrange_t *newrange = slab_allocate(range_cache);
if (newrange == NULL)
goto error;
@@ -1026,12 +963,12 @@ extern volatile struct limine_memmap_request pmm_liminemap;
void vmm_init() {
// set up initial state
__assert(sizeof(vmmcache_t) <= PAGE_SIZE);
range_cache = slab_create_new_cache_from_pmm(sizeof(vmmrange_t), 0, NULL, NULL);
__assert(range_cache);
MUTEX_INIT(&kernelspace.lock);
cachelist = newcache();
vmm_kernelctx.pagetable = arch_mmu_newtable();
__assert(cachelist && vmm_kernelctx.pagetable);
__assert(vmm_kernelctx.pagetable);
vmm_kernelctx.space.start = USERSPACE_START;
vmm_kernelctx.space.end = USERSPACE_END;
@@ -1067,7 +1004,7 @@ void vmm_init() {
printspace(&kernelspace);
}
INIT_ROUTINE_DEFINE(vmm, INIT_ROUTINE_FLAGS_NONE, vmm_init, mmu);
INIT_ROUTINE_DEFINE(vmm, INIT_ROUTINE_FLAGS_NONE, vmm_init, mmu, slab_early);
void vmm_apinit() {
vmm_switchcontext(&vmm_kernelctx);