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kolibrios/programs/system/os/malloc_internal.inc

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part of main system dll, not usable yet git-svn-id: svn://kolibrios.org@5195 a494cfbc-eb01-0410-851d-a64ba20cac60
2014-11-28 19:35:35 +01:00
MALLOC_ALIGNMENT = 8 ; must be power of two not less than 8, not greater than 4096
CHUNK_ALIGN_MASK = MALLOC_ALIGNMENT - 1
; ----------------------- Chunk representations ------------------------
;
; (The following includes lightly edited explanations by Colin Plumb.)
;
; The malloc_chunk declaration below is misleading (but accurate and
; necessary). It declares a "view" into memory allowing access to
; necessary fields at known offsets from a given base.
;
; Chunks of memory are maintained using a `boundary tag' method as
; originally described by Knuth. (See the paper by Paul Wilson
; ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a survey of such
; techniques.) Sizes of free chunks are stored both in the front of
; each chunk and at the end. This makes consolidating fragmented
; chunks into bigger chunks fast. The head fields also hold bits
; representing whether chunks are free or in use.
;
; Here are some pictures to make it clearer. They are "exploded" to
; show that the state of a chunk can be thought of as extending from
; the high 31 bits of the head field of its header through the
; prev_foot and PINUSE_BIT bit of the following chunk header.
;
; A chunk that's in use looks like:
;
; chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; | Size of previous chunk (if P = 0) |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |P|
; | Size of this chunk 1| +-+
; mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; | |
; +- -+
; | |
; +- -+
; | :
; +- size - sizeof(size_t) available payload bytes -+
; : |
; chunk-> +- -+
; | |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1|
; | Size of next chunk (may or may not be in use) | +-+
; mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
;
; And if it's free, it looks like this:
;
; chunk-> +- -+
; | User payload (must be in use, or we would have merged!) |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |P|
; | Size of this chunk 0| +-+
; mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; | Next pointer |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; | Prev pointer |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; | :
; +- size - sizeof(struct chunk) unused bytes -+
; : |
; chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; | Size of this chunk |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0|
; | Size of next chunk (must be in use, or we would have merged)| +-+
; mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; | :
; +- User payload -+
; : |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; |0|
; +-+
; Note that since we always merge adjacent free chunks, the chunks
; adjacent to a free chunk must be in use.
;
; Given a pointer to a chunk (which can be derived trivially from the
; payload pointer) we can, in O(1) time, find out whether the adjacent
; chunks are free, and if so, unlink them from the lists that they
; are on and merge them with the current chunk.
;
; Chunks always begin on even word boundaries, so the mem portion
; (which is returned to the user) is also on an even word boundary, and
; thus at least double-word aligned.
;
; The P (PINUSE_BIT) bit, stored in the unused low-order bit of the
; chunk size (which is always a multiple of two words), is an in-use
; bit for the *previous* chunk. If that bit is *clear*, then the
; word before the current chunk size contains the previous chunk
; size, and can be used to find the front of the previous chunk.
; The very first chunk allocated always has this bit set, preventing
; access to non-existent (or non-owned) memory. If pinuse is set for
; any given chunk, then you CANNOT determine the size of the
; previous chunk, and might even get a memory addressing fault when
; trying to do so.
;
; The C (CINUSE_BIT) bit, stored in the unused second-lowest bit of
; the chunk size redundantly records whether the current chunk is
; inuse (unless the chunk is mmapped). This redundancy enables usage
; checks within free and realloc, and reduces indirection when freeing
; and consolidating chunks.
;
; Each freshly allocated chunk must have both cinuse and pinuse set.
; That is, each allocated chunk borders either a previously allocated
; and still in-use chunk, or the base of its memory arena. This is
; ensured by making all allocations from the `lowest' part of any
; found chunk. Further, no free chunk physically borders another one,
; so each free chunk is known to be preceded and followed by either
; inuse chunks or the ends of memory.
;
; Note that the `foot' of the current chunk is actually represented
; as the prev_foot of the NEXT chunk. This makes it easier to
; deal with alignments etc but can be very confusing when trying
; to extend or adapt this code.
;
; The exceptions to all this are
;
; 1. The special chunk `top' is the top-most available chunk (i.e.,
; the one bordering the end of available memory). It is treated
; specially. Top is never included in any bin, is used only if
; no other chunk is available. In effect,
; the top chunk is treated as larger (and thus less well
; fitting) than any other available chunk. The top chunk
; doesn't update its trailing size field since there is no next
; contiguous chunk that would have to index off it. However,
; space is still allocated for it (TOP_FOOT_SIZE) to enable
; separation or merging when space is extended.
;
; 2. Chunks allocated via mmap, have both cinuse and pinuse bits
; cleared in their head fields. Because they are allocated
; one-by-one, each must carry its own prev_foot field, which is
; also used to hold the offset this chunk has within its mmapped
; region, which is needed to preserve alignment. Each mmapped
; chunk is trailed by the first two fields of a fake next-chunk
; for sake of usage checks.
;
struct malloc_chunk
prev_foot dd ? ; size of previous chunk (if free)
head dd ? ; size and inuse bits
data rd 0 ; label for data (if busy)
fd dd ? ; pointer to data in next malloc_chunk (if free)
bk dd ? ; pointer to data in prev malloc_chunk (if free)
ends
mchunk_prev_foot = malloc_chunk.prev_foot - malloc_chunk.data
mchunk_head = malloc_chunk.head - malloc_chunk.data
mchunk_fd = malloc_chunk.fd - malloc_chunk.data
mchunk_bk = malloc_chunk.bk - malloc_chunk.data
; ------------------- Chunks sizes and alignments -----------------------
MCHUNK_SIZE = sizeof.malloc_chunk
if FOOTERS
CHUNK_OVERHEAD = 8
else
CHUNK_OVERHEAD = 4
end if
; MMapped chunks need a second word of overhead ...
MMAP_CHUNK_OVERHEAD = 8
; ... and additional padding for fake next-chunk at foot
MMAP_FOOT_PAD = 16
; The smallest size we can malloc is an aligned minimal chunk
MIN_CHUNK_SIZE = (MCHUNK_SIZE + CHUNK_ALIGN_MASK) and not CHUNK_ALIGN_MASK
; Bounds on request (not chunk) sizes.
MAX_REQUEST = (-MIN_CHUNK_SIZE) * 4
MIN_REQUEST = MIN_CHUNK_SIZE - CHUNK_OVERHEAD
; ------------------ Operations on head and foot fields -----------------
; The head field of a chunk is or'ed with PINUSE_BIT when previous
; adjacent chunk in use, and or'ed with CINUSE_BIT if this chunk is in
; use, unless mmapped, in which case both bits are cleared.
;
; FLAG4_BIT is not used by this malloc, but might be useful in extensions.
PINUSE_BIT = 1
CINUSE_BIT = 2
FLAG4_BIT = 4
INUSE_BITS = PINUSE_BIT + CINUSE_BIT
FLAG_BITS = PINUSE_BIT + CINUSE_BIT + FLAG4_BIT
; Head value for fenceposts
FENCEPOST_HEAD = 4 + INUSE_BITS
; ---------------------- Overlaid data structures -----------------------
; When chunks are not in use, they are treated as nodes of either
; lists or trees.
;
; "Small" chunks are stored in circular doubly-linked lists, and look
; like this:
;
; chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; | Size of previous chunk |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; `head:' | Size of chunk, in bytes |P|
; mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; | Forward pointer to next chunk in list |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; | Back pointer to previous chunk in list |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; | Unused space (may be 0 bytes long) .
; . .
; . |
;nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; `foot:' | Size of chunk, in bytes |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
;
; Larger chunks are kept in a form of bitwise digital trees (aka
; tries) keyed on chunksizes. Because malloc_tree_chunks are only for
; free chunks greater than 256 bytes, their size doesn't impose any
; constraints on user chunk sizes. Each node looks like:
;
; chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; | Size of previous chunk |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; `head:' | Size of chunk, in bytes |P|
; mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; | Forward pointer to next chunk of same size |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; | Back pointer to previous chunk of same size |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; | Pointer to left child (child[0]) |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; | Pointer to right child (child[1]) |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; | Pointer to parent |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; | bin index of this chunk |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; | Unused space .
; . |
;nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
; `foot:' | Size of chunk, in bytes |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
;
; Each tree holding treenodes is a tree of unique chunk sizes. Chunks
; of the same size are arranged in a circularly-linked list, with only
; the oldest chunk (the next to be used, in our FIFO ordering)
; actually in the tree. (Tree members are distinguished by a non-null
; parent pointer.) If a chunk with the same size an an existing node
; is inserted, it is linked off the existing node using pointers that
; work in the same way as fd/bk pointers of small chunks.
;
; Each tree contains a power of 2 sized range of chunk sizes (the
; smallest is 0x100 <= x < 0x180), which is is divided in half at each
; tree level, with the chunks in the smaller half of the range (0x100
; <= x < 0x140 for the top nose) in the left subtree and the larger
; half (0x140 <= x < 0x180) in the right subtree. This is, of course,
; done by inspecting individual bits.
;
; Using these rules, each node's left subtree contains all smaller
; sizes than its right subtree. However, the node at the root of each
; subtree has no particular ordering relationship to either. (The
; dividing line between the subtree sizes is based on trie relation.)
; If we remove the last chunk of a given size from the interior of the
; tree, we need to replace it with a leaf node. The tree ordering
; rules permit a node to be replaced by any leaf below it.
;
; The smallest chunk in a tree (a common operation in a best-fit
; allocator) can be found by walking a path to the leftmost leaf in
; the tree. Unlike a usual binary tree, where we follow left child
; pointers until we reach a null, here we follow the right child
; pointer any time the left one is null, until we reach a leaf with
; both child pointers null. The smallest chunk in the tree will be
; somewhere along that path.
;
; The worst case number of steps to add, find, or remove a node is
; bounded by the number of bits differentiating chunks within
; bins. Under current bin calculations, this ranges from 6 up to 21
; (for 32 bit sizes) or up to 53 (for 64 bit sizes). The typical case
; is of course much better.
;
; All large chunks which have been extended after last call to sys_trim
; are kept in a single-linked list with head inside malloc_state.
; For a chunk not in the list, release_fd/release_bk point to itself.
struct malloc_tree_chunk malloc_chunk
left_child dd ? ; pointer to malloc_tree_chunk.data
right_child dd ? ; pointer to malloc_tree_chunk.data
parent dd ? ; pointer to malloc_tree_chunk.data
index dd ?
ends
tchunk_left_child = malloc_tree_chunk.left_child - malloc_chunk.data
tchunk_right_child = malloc_tree_chunk.right_child - malloc_chunk.data
tchunk_parent = malloc_tree_chunk.parent - malloc_chunk.data
tchunk_index = malloc_tree_chunk.index - malloc_chunk.data
tchunk_release_fd = mchunk_prev_foot - 8
tchunk_release_bk = tchunk_release_fd + 4
; ----------------------------- Segments --------------------------------
;
; Each malloc space may include non-contiguous segments, held in a
; list headed by an embedded malloc_segment record representing the
; top-most space. Large chunks that are directly allocated by mmap are not
; included in this list. They are instead independently created and
; destroyed without otherwise keeping track of them.
;
; Except for the top-most segment of an mstate, each segment record
; is kept at the tail of its segment. Segments are added by pushing
; segment records onto the list headed by &mstate.seg for the
; containing mstate.
;
struct malloc_segment
base dd ? ; base address
size dd ? ; allocated size
next dd ? ; pointer to next malloc_segment
ends
; ---------------------------- malloc_state -----------------------------
; A malloc_state holds all of the bookkeeping for a space.
; The main fields are:
;
; Top
; The topmost chunk of the currently active segment. Its size is
; cached in topsize. The actual size of topmost space is
; topsize+TOP_FOOT_SIZE, which includes space reserved for adding
; fenceposts and segment records if necessary when getting more
; space from the system.
;
; Designated victim (dv)
; This is the preferred chunk for servicing small requests that
; don't have exact fits. It is normally the chunk split off most
; recently to service another small request. Its size is cached in
; dvsize. The link fields of this chunk are not maintained since it
; is not kept in a bin.
;
; SmallBins
; An array of bin headers for free chunks. These bins hold chunks
; with sizes less than MIN_LARGE_SIZE bytes. Each bin contains
; chunks of all the same size, spaced 8 bytes apart. To simplify
; use in double-linked lists, each bin header acts as a malloc_chunk
; pointing to the real first node, if it exists (else pointing to
; itself). This avoids special-casing for headers. But to avoid
; waste, we allocate only the fd/bk pointers of bins, and then use
; repositioning tricks to treat these as the fields of a chunk.
;
; TreeBins
; Treebins are pointers to the roots of trees holding a range of
; sizes. There are 2 equally spaced treebins for each power of two
; from TREE_SHIFT to TREE_SHIFT+16. The last bin holds anything
; larger.
;
; Bin maps
; There is one bit map for small bins ("smallmap") and one for
; treebins ("treemap). Each bin sets its bit when non-empty, and
; clears the bit when empty. Bit operations are then used to avoid
; bin-by-bin searching -- nearly all "search" is done without ever
; looking at bins that won't be selected. The bit maps
; conservatively use 32 bits per map word, even if on 64bit system.
; For a good description of some of the bit-based techniques used
; here, see Henry S. Warren Jr's book "Hacker's Delight" (and
; supplement at http://hackersdelight.org/). Many of these are
; intended to reduce the branchiness of paths through malloc etc, as
; well as to reduce the number of memory locations read or written.
;
; Segments
; A list of segments headed by an embedded malloc_segment record
; representing the initial space.
;
; Magic tag
; A cross-check field that should always hold same value as malloc_magic.
;
; Max allowed footprint
; The maximum allowed bytes to allocate from system (zero means no limit)
;
; Flags
; Bits recording whether to use locks
;
; Statistics
; Each space keeps track of current and maximum system memory.
;
; Trim support
; Fields holding the amount of unused topmost memory that should trigger
; trimming, and a counter to force periodic scanning to release unused
; non-topmost segments.
;
; Locking
; If USE_LOCKS is defined, the "mutex" lock is acquired and released
; around every public call using this mspace.
;typedef struct malloc_segment msegment;
;typedef struct malloc_segment* msegmentptr;
NSMALLBINS = 32
NTREEBINS = 32
SMALLBIN_SHIFT = 3
SMALLBIN_WIDTH = 1 shl SMALLBIN_SHIFT
TREEBIN_SHIFT = 8
MIN_LARGE_SIZE = 1 shl TREEBIN_SHIFT
assert MIN_LARGE_SIZE = NSMALLBINS * SMALLBIN_WIDTH
MAX_SMALL_SIZE = MIN_LARGE_SIZE - 1
MAX_SMALL_REQUEST = MAX_SMALL_SIZE - CHUNK_ALIGN_MASK - CHUNK_OVERHEAD
struct malloc_state
smallmap dd ? ; bitmap for non-empty small bins
treemap dd ? ; bitmap for non-empty tree bins
dvsize dd ? ; designated victim size
topsize dd ? ; size of free top area
dv dd ? ; pointer to malloc_chunk.data of designated victim
top dd ? ; pointer to malloc_chunk.data of top area
topmax dd ? ; maximum value of top after prev release check
release_checks dd ? ; counter before next release check
release_list rd 2 ; list of malloc_tree_chunk with pages to release
mmap_list rd 2 ; list of mmapped chunks
magic dd ? ; for FOOTERS
smallbins rd NSMALLBINS*2 ; pointers to malloc_chunk.data
treebins rd NTREEBINS ; pointers to malloc_tree_chunk.data
footprint dd ?
max_footprint dd ?
footprint_limit dd ? ; zero means no limit
mmap_threshold dd ?
segment_size dd ?
mflags dd ?
mutex dd ?
seg malloc_segment
ends
; Bits for malloc_state.mflags
USE_LOCK_BIT = 2
;
TOP_FOOT_SIZE = (-8) and CHUNK_ALIGN_MASK + (sizeof.malloc_segment + CHUNK_OVERHEAD + CHUNK_ALIGN_MASK) and not CHUNK_ALIGN_MASK + MIN_CHUNK_SIZE
SYS_ALLOC_PADDING = TOP_FOOT_SIZE + MALLOC_ALIGNMENT
; in: ebp -> malloc_state
; out: eax -> malloc_segment
macro segment_holding address
{
lea eax, [ebp+malloc_state.seg]
@@:
mov ecx, address
sub ecx, [eax+malloc_segment.base]
cmp ecx, [eax+malloc_segment.size]
jb @f
mov eax, [eax+malloc_segment.next]
test eax, eax
jnz @b
@@:
}
; in: ebp -> malloc_state
macro lock_heap
{
local .done
test [ebp+malloc_state.mflags], USE_LOCK_BIT
jz .done
; TODO: use mutex when it will be available in kernel API
@@:
mov eax, 1
xchg [ebp+malloc_state.mutex], eax
test eax, eax
jz .done
mov eax, 68
mov ebx, 1
call FS_SYSCALL_PTR
jmp @b
.done:
}
; in: ebp -> malloc_state
macro unlock_heap
{
local .done
test [ebp+malloc_state.mflags], USE_LOCK_BIT
jz .done
; TODO: use mutex when it will be available in kernel API
mov [ebp+malloc_state.mutex], 0
.done:
}
; ---------------------------- Indexing Bins ----------------------------
MIN_SMALL_INDEX = MIN_CHUNK_SIZE shr SMALLBIN_SHIFT
; in: sizereg = size, must be >= 1 shl TREEBIN_SHIFT
; out: ecx = index, sizereg = size << leftshift_for_tree_index
macro compute_tree_index sizereg
{
mov ecx, NTREEBINS-1
cmp sizereg, 0xC000 shl TREEBIN_SHIFT
jae @f
bsr ecx, sizereg
ror sizereg, cl
adc ecx, ecx
lea sizereg, [(sizereg-1)*2]
sub ecx, TREEBIN_SHIFT*2
@@:
}
; ----------------------- Runtime Check Support -------------------------
macro mark_inuse_foot where
{
if FOOTERS
mov ebx, ebp
xor ebx, [malloc_magic]
mov [where+mchunk_prev_foot], ebx
end if
}
; ----------------------- Operations on smallbins -----------------------
; Link a free chunk into a smallbin
; in: ebp -> malloc_state, esi -> malloc_chunk.data, edx = size
macro insert_small_chunk_noshift
{
bts [ebp+malloc_state.smallmap], edx
mov ecx, [ebp+malloc_state.smallbins+edx*8+mchunk_fd]
lea edx, [ebp+malloc_state.smallbins+edx*8]
mov [ecx+mchunk_bk], esi
mov [edx+mchunk_fd], esi
mov [esi+mchunk_fd], ecx
mov [esi+mchunk_bk], edx
}
macro insert_small_chunk
{
shr edx, SMALLBIN_SHIFT
insert_small_chunk_noshift
}
; Unlink a chunk from a smallbin
; in: ebp -> malloc_state, eax -> malloc_chunk.data, edx = size
macro unlink_small_chunk
{
mov ecx, [eax+mchunk_fd]
mov ebx, [eax+mchunk_bk]
cmp [ecx+mchunk_bk], eax
jnz heap_corrupted
cmp [ebx+mchunk_fd], eax
jnz heap_corrupted
mov [ecx+mchunk_bk], ebx
mov [ebx+mchunk_fd], ecx
cmp ecx, ebx
jnz @f
shr edx, SMALLBIN_SHIFT
btr [ebp+malloc_state.smallmap], edx
@@:
}
; Unlink the first chunk from a smallbin
; in: ebp -> malloc_state, edx -> list header, eax -> malloc_chunk.data
; in: ecx = smallbin index
macro unlink_first_small_chunk
{
mov ebx, [eax+mchunk_fd]
cmp [ebx+mchunk_bk], eax
jnz heap_corrupted
mov [ebx+mchunk_bk], edx
mov [edx+mchunk_fd], ebx
cmp edx, ebx
jnz @f
btr [ebp+malloc_state.smallmap], ecx
@@:
}
; Replace dv node, binning the old one
; Used only when dvsize known to be small
; in: ebp -> malloc_state, ecx = chunk size, edx -> malloc_chunk.data
macro replace_dv
{
mov esi, [ebp+malloc_state.dv]
mov [ebp+malloc_state.dv], edx
mov edx, [ebp+malloc_state.dvsize]
mov [ebp+malloc_state.dvsize], ecx
shr edx, SMALLBIN_SHIFT
jz @f
insert_small_chunk_noshift ; ebp,esi,edx
@@:
}
; ------------------------- Operations on trees -------------------------
; Insert chunk into tree
; in: ebp -> malloc_state, esi -> malloc_chunk.data, edx = size
macro insert_large_chunk return_action
{
local .not_first, .loop, .exact_size
mov edi, edx
compute_tree_index edx
lea ebx, [ebp+malloc_state.treebins+ecx*4]
mov [esi+tchunk_index], ecx
mov dword [esi+tchunk_left_child], 0
mov dword [esi+tchunk_right_child], 0
bts [ebp+malloc_state.treemap], ecx
jc .not_first
mov [ebx], esi
mov [esi+tchunk_parent], ebx
mov [esi+mchunk_fd], esi
mov [esi+mchunk_bk], esi
return_action
.not_first:
mov ebx, [ebx]
.loop:
mov ecx, [ebx+mchunk_head]
and ecx, not FLAG_BITS
cmp ecx, edi
jz .exact_size
xor ecx, ecx
add edx, edx
adc ecx, ecx
lea ecx, [ebx+tchunk_left_child+ecx*4]
cmp dword [ecx], 0
jz @f
mov ebx, [ecx]
jmp .loop
@@:
mov [ecx], esi
mov [esi+tchunk_parent], ebx
mov [esi+mchunk_fd], esi
mov [esi+mchunk_bk], esi
return_action
.exact_size:
mov edx, [ebx+mchunk_fd]
mov [edx+mchunk_bk], esi
mov [ebx+mchunk_fd], esi
mov [esi+mchunk_fd], edx
mov [esi+mchunk_bk], ebx
mov dword [esi+tchunk_parent], 0
return_action
}
; Unlink steps:
;
; 1. If x is a chained node, unlink it from its same-sized fd/bk links
; and choose its bk node as its replacement.
; 2. If x was the last node of its size, but not a leaf node, it must
; be replaced with a leaf node (not merely one with an open left or
; right), to make sure that lefts and rights of descendents
; correspond properly to bit masks. We use the rightmost descendent
; of x. We could use any other leaf, but this is easy to locate and
; tends to counteract removal of leftmosts elsewhere, and so keeps
; paths shorter than minimally guaranteed. This doesn't loop much
; because on average a node in a tree is near the bottom.
; 3. If x is the base of a chain (i.e., has parent links) relink
; x's parent and children to x's replacement (or null if none).
; in: ebp -> malloc_state, eax -> malloc_tree_chunk.data
; destroys ebx,edx,esi, keeps eax,ecx
macro unlink_large_chunk
{
local .last, .common1, .find_rightmost_child, .done, .advance_right, .remove_root
mov esi, [eax+tchunk_parent]
cmp [eax+mchunk_bk], eax
jz .last
mov edx, [eax+mchunk_fd]
mov ebx, [eax+mchunk_bk]
cmp [edx+mchunk_bk], eax
jnz heap_corrupted
cmp [ebx+mchunk_fd], eax
jnz heap_corrupted
mov [edx+mchunk_bk], ebx
mov [ebx+mchunk_fd], edx
jmp .common1
.last:
mov ebx, [eax+tchunk_right_child]
lea edx, [eax+tchunk_right_child]
test ebx, ebx
jnz .find_rightmost_child
mov ebx, [eax+tchunk_left_child]
lea edx, [eax+tchunk_left_child]
test ebx, ebx
jz .common1
.find_rightmost_child:
cmp dword [ebx+tchunk_right_child], 0
jnz .advance_right
cmp dword [ebx+tchunk_left_child], 0
jz @f
lea edx, [ebx+tchunk_left_child]
mov ebx, [ebx+tchunk_left_child]
jmp .find_rightmost_child
.advance_right:
lea edx, [ebx+tchunk_right_child]
mov ebx, [ebx+tchunk_right_child]
jmp .find_rightmost_child
@@:
mov dword [edx], 0
.common1:
test esi, esi
jz .done
mov edx, [eax+tchunk_index]
cmp [ebp+malloc_state.treebins+edx*4], eax
jz .remove_root
xor edx, edx
cmp [esi+tchunk_left_child], eax
setnz dl
mov [esi+tchunk_left_child+edx*4], ebx
jmp @f
.remove_root:
mov [ebp+malloc_state.treebins+edx*4], ebx
test ebx, ebx
jnz @f
btr [ebp+malloc_state.treemap], edx
@@:
test ebx, ebx
jz .done
mov [ebx+tchunk_parent], esi
cmp dword [eax+tchunk_left_child], 0
jz @f
mov edx, [eax+tchunk_left_child]
mov [ebx+tchunk_left_child], edx
mov [edx+tchunk_parent], ebx
@@:
cmp dword [eax+tchunk_right_child], 0
jz @f
mov edx, [eax+tchunk_right_child]
mov [ebx+tchunk_right_child], edx
mov [edx+tchunk_parent], ebx
@@:
.done:
}
; Relays to large vs small bin operations
; in: ebp -> malloc_state, esi -> malloc_chunk.data, edx = size
macro insert_chunk return_action
{
local .large
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jae .large
insert_small_chunk ; ebp, esi, edx
return_action
.large:
insert_large_chunk return_action ; ebp, esi, edx
}
; in: ebp -> malloc_state, eax -> malloc_chunk.data, edx = size
macro unlink_chunk
{
local .large, .common
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jae .large
unlink_small_chunk ; ebp, eax, edx
jmp .common
.large:
unlink_large_chunk ; ebp, eax
.common:
}
; ----------------------- Direct-mmapping chunks -----------------------
; Since a system call is used in these functions anyway,
; the speed is not of primary value here.
; Directly mmapped chunks are set up with an offset to the start of
; the mmapped region stored in the prev_foot field of the chunk. This
; allows reconstruction of the required argument to MUNMAP when freed,
; and also allows adjustment of the returned chunk to meet alignment
; requirements (especially in memalign).
; in: ebp -> malloc_state, ecx = nb
; out: eax -> allocated block on success, 0 on failure
; destroys: eax, ebx, ecx
assert MALLOC_ALIGNMENT <= 4096 ; it is important here
proc mmap_alloc
add ecx, 8*4 + CHUNK_ALIGN_MASK + 0xFFF
jc .error
and ecx, not 0xFFF
cmp [ebp+malloc_state.footprint_limit], 0
jz @f
mov eax, [ebp+malloc_state.footprint]
add eax, ecx
jc .error
cmp eax, [ebp+malloc_state.footprint_limit]
ja .error
@@:
mov eax, 68
mov ebx, 12
call FS_SYSCALL_PTR
test eax, eax
jz .error
lea ebx, [ebp+malloc_state.mmap_list]
mov edx, [ebp+malloc_state.mmap_list]
cmp [edx+4], ebx
jnz heap_corrupted
mov [ebx], eax
mov [edx+4], eax
mov [eax], edx
mov [eax+4], ebx
add eax, ((-16) and CHUNK_ALIGN_MASK) + 16
lea edx, [ecx-((-16) and CHUNK_ALIGN_MASK)-8-MMAP_FOOT_PAD]
mov dword [eax+mchunk_prev_foot], ((-16) and CHUNK_ALIGN_MASK) + 16
mov [eax+mchunk_head], edx
mark_inuse_foot eax+edx
mov dword [eax+edx+mchunk_head], FENCEPOST_HEAD
mov dword [eax+edx+4+mchunk_head], 0
add ecx, [ebp+malloc_state.footprint]
mov [ebp+malloc_state.footprint], ecx
cmp ecx, [ebp+malloc_state.max_footprint]
jb @f
mov [ebp+malloc_state.max_footprint], ecx
@@:
ret
.error:
xor eax, eax
ret
endp
; in: ebp -> malloc_state, ecx = nb, edx -> old malloc_chunk.data
; in: ebx = can_move: if zero, fail unless realloc in place is possible
proc mmap_resize
mov eax, [edx+mchunk_head]
cmp ecx, NSMALLBINS shl SMALLBIN_SHIFT
jb .error
sub eax, ecx
jc .realloc
cmp eax, 4
jb .realloc
cmp eax, 0x2000
ja .realloc
mov eax, edx
ret
.realloc:
test ebx, ebx
jz .error
sub edx, [edx+mchunk_prev_foot]
mov eax, [edx]
mov ebx, [edx+4]
cmp [eax+4], edx
jnz heap_corrupted
cmp [ebx], edx
jnz heap_corrupted
mov [eax+4], ebx
mov [ebx], eax
mov eax, 68
mov ebx, 20
add ecx, 8*4 + CHUNK_ALIGN_MASK + 0xFFF
and ecx, not 0xFFF
call FS_SYSCALL_PTR
test eax, eax
jz .error
mov ebx, [eax]
mov [ebx+4], eax
mov ebx, [eax+4]
mov [ebx], eax
add eax, ((-16) and CHUNK_ALIGN_MASK)+16
mov edx, [eax+mchunk_head]
add edx, ((-16) and CHUNK_ALIGN_MASK)+8+MMAP_FOOT_PAD
lea ebx, [ecx-((-16) and CHUNK_ALIGN_MASK)-8-MMAP_FOOT_PAD]
mov [eax+mchunk_head], ebx
mark_inuse_foot eax+ecx-((-16) and CHUNK_ALIGN_MASK)-8-MMAP_FOOT_PAD
mov dword [eax+ecx-((-16) and CHUNK_ALIGN_MASK)-8-MMAP_FOOT_PAD+mchunk_head], FENCEPOST_HEAD
mov dword [eax+ecx-((-16) and CHUNK_ALIGN_MASK)-8-MMAP_FOOT_PAD+4+mchunk_head], 0
add ecx, [ebp+malloc_state.footprint]
sub ecx, edx
mov [ebp+malloc_state.footprint], ecx
cmp ecx, [ebp+malloc_state.max_footprint]
jb @f
mov [ebp+malloc_state.max_footprint], ecx
@@:
ret
.error:
xor eax, eax
ret
endp
; -------------------------- mspace management --------------------------
; Initialize top chunk and its size
; in: eax -> malloc_state, ebx -> malloc_chunk.data for top, ecx = size
; ebx must be aligned to MALLOC_ALIGNMENT
macro init_top
{
mov [eax+malloc_state.top], ebx
mov [eax+malloc_state.topmax], ebx
mov [eax+malloc_state.topsize], ecx
lea edx, [ecx+PINUSE_BIT]
mov [ebx+mchunk_head], edx
mov dword [ebx+ecx+mchunk_head], TOP_FOOT_SIZE
}
; Same as init_top, but return the previous top
; in: ebp -> malloc_state, eax -> malloc_chunk.data for top, ecx = size
; out: edx -> malloc_chunk.data for old top
macro reinit_top
{
lea edx, [ecx+PINUSE_BIT]
mov [eax+mchunk_head], edx
mov dword [eax+ecx+mchunk_head], TOP_FOOT_SIZE
mov edx, [ebp+malloc_state.top]
mov [ebp+malloc_state.top], eax
mov [ebp+malloc_state.topmax], eax
mov [ebp+malloc_state.topsize], ecx
}
; Initialize bins for a new mstate that is otherwise zeroed out
; in: eax -> malloc_state
macro init_bins
{
lea ebx, [eax+malloc_state.smallbins]
mov edx, NSMALLBINS
@@:
mov [ebx+mchunk_fd], ebx
mov [ebx+mchunk_bk], ebx
add ebx, 8
dec edx
jnz @b
}
; Add a segment to hold a new noncontiguous region
; in: ebp -> malloc_state, eax = segment base, ecx = segment size
malloc_seg_chunk_size = (sizeof.malloc_segment + CHUNK_OVERHEAD + CHUNK_ALIGN_MASK) and not CHUNK_ALIGN_MASK
macro add_segment
{
local .nothing, .large
push edi
push eax ecx
; Ensure alignment for top
add eax, 8 + ((-8) and CHUNK_ALIGN_MASK)
sub ecx, TOP_FOOT_SIZE + ((-8) and CHUNK_ALIGN_MASK)
; reset top to new space
reinit_top
segment_holding edx
mov ecx, [eax+malloc_segment.base]
add ecx, [eax+malloc_segment.size]
lea ebx, [edx+MIN_CHUNK_SIZE]
lea eax, [ecx - malloc_seg_chunk_size - MALLOC_ALIGNMENT]
cmp eax, ebx
jae @f
mov eax, edx
@@:
; Set up segment record
mov dword [eax+mchunk_head], malloc_seg_chunk_size+PINUSE_BIT+CINUSE_BIT
mark_inuse_foot eax+malloc_seg_chunk_size
; Push current record
mov ebx, [ebp+malloc_state.seg.base]
mov [eax+malloc_segment.base], ebx
mov ebx, [ebp+malloc_state.seg.size]
mov [eax+malloc_segment.size], ebx
mov ebx, [ebp+malloc_state.seg.next]
mov [eax+malloc_segment.next], ebx
popd [ebp+malloc_state.seg.size] [ebp+malloc_state.seg.base]
mov [ebp+malloc_state.seg.next], eax
; Insert trailing fenceposts
mov esi, edx
sub edx, eax
lea edi, [eax+malloc_seg_chunk_size+mchunk_head]
mov eax, FENCEPOST_HEAD
sub ecx, edi
shr ecx, 2
rep stosd
; Insert the rest of old top into a bin as an ordinary free chunk
neg edx
jz .nothing
and dword [esi+edx+mchunk_head], not PINUSE_BIT
lea ecx, [edx+PINUSE_BIT]
mov [esi+mchunk_head], ecx
mov [esi+edx+mchunk_prev_foot], edx
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jb .small
lea ecx, [esi+edx]
mov [ecx+tchunk_release_fd], ecx
mov [ecx+tchunk_release_bk], ecx
insert_large_chunk <jmp .nothing> ; ebp, esi, edx
.small:
insert_small_chunk ; ebp, esi, edx
.nothing:
pop edi
}
; -------------------------- System allocation --------------------------
; Get memory from system using MMAP
; in: ebp -> malloc_state, esi = size
; Allocate a new segment and a chunk inside that segment.
; Algorithm of segment size calculation:
; 1. Calculate minimal size required to
; successful subsequent allocation of a chunk.
; 2. Set maximum of it and malloc_state.segment_size as the new size.
; 3. If footprint limit is set and the selected size would overflow it,
; decrease to the maximum allowed by the limit.
; 4. If the selected size is less than the minimal size, fail.
; 5. Call the kernel. If failed, retry several times halving
; the requested size until either allocation succeeds or
; the minimal size is reached; in the former case, try one last time
; requesting the minimal size. If failed, pass the fail to the caller.
; 6. If allocation succeeded, add the final size to malloc_state.segment_size
; for subsequent allocations.
proc sys_alloc
call trim_top
mov edx, esi
add edx, SYS_ALLOC_PADDING + 0xFFF
jc .fail
and edx, not 0xFFF
; edx = minimal memory required
mov ecx, [ebp+malloc_state.segment_size]
cmp ecx, edx
ja @f
mov ecx, edx
@@:
mov ebx, [ebp+malloc_state.footprint_limit]
test ebx, ebx
jz @f
sub ebx, [ebp+malloc_state.footprint]
cmp ecx, ebx
jb @f
mov ecx, ebx
@@:
cmp ecx, edx
jb .fail
.retry:
mov eax, 68
mov ebx, 12
call FS_SYSCALL_PTR
test eax, eax
jnz .ok
cmp ecx, edx
jbe .fail
shr ecx, 1
cmp ecx, edx
jae .retry
mov ecx, edx
jmp .retry
.fail:
mov FS_ERRNO, ENOMEM
xor eax, eax
ret
.ok:
add [ebp+malloc_state.segment_size], ecx
add [ebp+malloc_state.footprint], ecx
mov ebx, [ebp+malloc_state.footprint]
cmp ebx, [ebp+malloc_state.max_footprint]
jb @f
mov [ebp+malloc_state.max_footprint], ebx
@@:
push esi
add_segment ; ebp, eax, ecx
pop esi
mov ecx, [ebp+malloc_state.topsize]
sub ecx, esi
jbe .fail
mov [ebp+malloc_state.topsize], ecx
mov eax, [ebp+malloc_state.top]
add [ebp+malloc_state.top], esi
add [ebp+malloc_state.topmax], esi
lea edx, [ecx+PINUSE_BIT]
mov [eax+esi+mchunk_head], edx
lea edx, [esi+PINUSE_BIT+CINUSE_BIT]
mov [eax+mchunk_head], edx
mark_inuse_foot eax+esi
ret
endp
; ----------------------- system deallocation --------------------------
proc chunk_trim
add edx, 0xFFF
and edx, not 0xFFF
and esi, not 0xFFF
sub esi, edx
jbe .nothing
segment_holding edx
mov ecx, [eax+malloc_segment.base]
mov eax, 68
mov ebx, 26
sub edx, ecx
call FS_SYSCALL_PTR
.nothing:
ret
endp
proc trim_top
mov edx, [ebp+malloc_state.top]
xor edx, [ebp+malloc_state.topmax]
test edx, not 0xFFF
jz .nothing
push esi
mov edx, [ebp+malloc_state.top]
mov esi, [ebp+malloc_state.topmax]
mov [ebp+malloc_state.topmax], edx
add esi, 0xFFF
call chunk_trim
pop esi
.nothing:
ret
endp
proc sys_trim
call trim_top
push edi
lea edi, [ebp+malloc_state.release_list-tchunk_release_fd]
mov eax, [ebp+malloc_state.release_list]
push edi
.release_list:
cmp eax, [esp]
jz .release_done
mov edi, eax
mov esi, [eax+mchunk_prev_foot]
sub eax, [eax+mchunk_prev_foot]
lea edx, [eax+sizeof.malloc_tree_chunk-malloc_chunk.data]
lea esi, [eax+esi+tchunk_release_fd]
call chunk_trim
mov eax, [edi+tchunk_release_fd]
mov [edi+tchunk_release_fd], edi
mov [edi+tchunk_release_bk], edi
jmp .release_list
.release_done:
mov [ebp+malloc_state.release_list+0], eax
mov [ebp+malloc_state.release_list+4], eax
pop edi edi
mov [ebp+malloc_state.release_checks], RELEASE_CHECK_RATE
ret
endp
macro trim_if_should
{
dec [ebp+malloc_state.release_checks]
jnz @f
call sys_trim
@@:
}
; ---------------------------- malloc ---------------------------
; allocate a large request from the best fitting chunk in a treebin
; if succeeded, unlock the heap and return
; if failed, go ahead
; in: ebp -> malloc_state, esi = nb
macro tmalloc_large_and_return
{
local .find_in_bin, .follow_right, .try_next_bin, .found_subtree, .found_match, .no_new_chunk, .follow_left, .nothing
push edi
macro ret \{
pop edi
ret
\}
push 0
push 0
mov eax, esi
compute_tree_index eax
; ecx = idx, eax = sizebits
sub [esp], esi
; edx = rsize
cmp [ebp+malloc_state.treebins+ecx*4], 0
jz .try_next_bin
; Traverse tree for this bin looking for node with size == nb
mov edi, [ebp+malloc_state.treebins+ecx*4]
xor ebx, ebx ; The deepest untaken right subtree
.find_in_bin:
mov edx, [edi+mchunk_head]
and edx, not FLAG_BITS
sub edx, esi
cmp [esp], edx
jbe @f
mov [esp], edx
mov [esp+4], edi
test edx, edx
jz .found_match
@@:
add eax, eax
jc .follow_right
cmp dword [edi+tchunk_right_child], 0
jz @f
mov ebx, [edi+tchunk_right_child]
@@:
cmp dword [edi+tchunk_left_child], 0
mov edi, [edi+tchunk_left_child]
jnz .find_in_bin
jmp @f
.follow_right:
cmp dword [edi+tchunk_right_child], 0
mov edi, [edi+tchunk_right_child]
jnz .find_in_bin
@@:
mov edi, ebx ; set t to least subtree holding sizes > nb
test ebx, ebx
jnz .found_subtree
cmp dword [esp+4], 0
jnz .found_match
.try_next_bin:
; set t to root of next non-empty treebin
mov eax, [ebp+malloc_state.treemap]
shr eax, cl
shr eax, 1
jz .nothing
bsf eax, eax
add eax, ecx
mov edi, [ebp+malloc_state.treebins+(eax+1)*4]
.found_subtree:
; find smallest of tree or subtree
mov edx, [edi+mchunk_head]
and edx, not FLAG_BITS
sub edx, esi
cmp [esp], edx
jbe @f
mov [esp], edx
mov [esp+4], edi
@@:
cmp dword [edi+tchunk_left_child], 0
jnz .follow_left
cmp dword [edi+tchunk_right_child], 0
mov edi, [edi+tchunk_right_child]
jnz .found_subtree
cmp dword [esp+4], 0
jz .nothing
.found_match:
; If dv is a better fit, return 0 so malloc will use it
mov eax, [ebp+malloc_state.dvsize]
sub eax, esi
cmp [esp], eax
jae .nothing
mov eax, [esp+4]
cmp dword [esp], NSMALLBINS shl SMALLBIN_SHIFT
jae @f
mov ecx, [esp]
add ecx, esi
add ecx, eax
mov ebx, [ecx+tchunk_release_fd]
mov edx, [ecx+tchunk_release_bk]
cmp [ebx+tchunk_release_bk], ecx
jnz heap_corrupted
cmp [edx+tchunk_release_fd], ecx
jnz heap_corrupted
mov [ebx+tchunk_release_bk], edx
mov [edx+tchunk_release_fd], ebx
@@:
mov ecx, esi
unlink_large_chunk ; ebp, eax
cmp dword [esp], MIN_CHUNK_SIZE
jb .no_new_chunk
lea edx, [ecx+PINUSE_BIT+CINUSE_BIT]
mov [eax+mchunk_head], edx
mark_inuse_foot eax+ecx
lea esi, [eax+ecx]
mov edx, [esp]
lea ecx, [edx+PINUSE_BIT]
mov [esi+mchunk_head], ecx
mov [esi+edx+mchunk_prev_foot], edx
add esp, 8
macro unlock_ret \{
unlock_heap
ret
\}
insert_chunk unlock_ret ; ebp, esi, edx
purge unlock_ret
.no_new_chunk:
add ecx, [esp]
lea edx, [ecx+PINUSE_BIT+CINUSE_BIT]
mov [eax+mchunk_head], edx
or dword [eax+ecx+mchunk_head], PINUSE_BIT
mark_inuse_foot eax+ecx
add esp, 8
unlock_heap
ret
.follow_left:
mov edi, [edi+tchunk_left_child]
jmp .found_subtree
.nothing:
add esp, 8
pop edi
purge ret
}
; allocate a small request from the best fitting chunk in a treebin
; in: ebp -> malloc_state, esi = size
macro tmalloc_small_and_return
{
local .follow_left, .found_best, .no_new_chunk
bsf ecx, [ebp+malloc_state.treemap]
mov eax, [ebp+malloc_state.treebins+ecx*4]
mov edx, eax
mov ecx, [eax+mchunk_head]
and ecx, not FLAG_BITS
sub ecx, esi
@@:
cmp dword [edx+tchunk_left_child], 0
jnz .follow_left
cmp dword [edx+tchunk_right_child], 0
jz .found_best
mov edx, [edx+tchunk_right_child]
mov ebx, [edx+mchunk_head]
and ebx, not FLAG_BITS
sub ebx, esi
cmp ecx, ebx
jbe @b
mov eax, edx
mov ecx, ebx
jmp @b
.follow_left:
mov edx, [edx+tchunk_left_child]
mov ebx, [edx+mchunk_head]
and ebx, not FLAG_BITS
sub ebx, esi
cmp ecx, ebx
jbe @b
mov eax, edx
mov ecx, ebx
jmp @b
.found_best:
push esi
cmp ecx, NSMALLBINS shl SMALLBIN_SHIFT
jae @f
add esi, ecx
add esi, eax
mov ebx, [esi+tchunk_release_fd]
mov edx, [esi+tchunk_release_bk]
cmp [ebx+tchunk_release_bk], esi
jnz heap_corrupted
cmp [edx+tchunk_release_fd], esi
jnz heap_corrupted
mov [ebx+tchunk_release_bk], edx
mov [edx+tchunk_release_fd], ebx
@@:
unlink_large_chunk ; ebp, eax
pop esi
cmp ecx, MIN_CHUNK_SIZE
jb .no_new_chunk
lea edx, [eax+esi]
lea ebx, [esi+PINUSE_BIT+CINUSE_BIT]
mov [eax+mchunk_head], ebx
mark_inuse_foot edx
lea ebx, [ecx+PINUSE_BIT]
mov [edx+mchunk_head], ebx
mov [edx+ecx+mchunk_prev_foot], ecx
replace_dv ; ebp, ecx, edx
unlock_heap
ret
.no_new_chunk:
lea edx, [ecx+esi+PINUSE_BIT+CINUSE_BIT]
add ecx, esi
mov [eax+mchunk_head], edx
or dword [eax+ecx+mchunk_head], PINUSE_BIT
mark_inuse_foot eax+ecx
unlock_heap
ret
}
; in: ebp -> malloc_state
; in: [bytes] = stack var with number of bytes to allocate
; out: eax -> allocated data
macro do_malloc
{
;
; Basic algorithm:
; If a small request (< 256 bytes minus per-chunk overhead):
; 1. If one exists, use a remainderless chunk in associated smallbin.
; (Remainderless means that there are too few excess bytes to
; represent as a chunk.)
; 2. If it is big enough, use the dv chunk, which is normally the
; chunk adjacent to the one used for the most recent small request.
; 3. If one exists, split the smallest available chunk in a bin,
; saving remainder in dv.
; 4. If it is big enough, use the top chunk.
; 5. If available, get memory from system and use it
; Otherwise, for a large request:
; 1. Find the smallest available binned chunk that fits, and use it
; if it is better fitting than dv chunk, splitting if necessary.
; 2. If better fitting than any binned chunk, use the dv chunk.
; 3. If request size >= mmap threshold, try to directly mmap this chunk.
; 4. If it is big enough, use the top chunk.
; 5. If available, get memory from system and use it
;
lock_heap
mov eax, [bytes]
cmp [bytes], MAX_SMALL_REQUEST
ja .large
mov ecx, MIN_CHUNK_SIZE
cmp eax, MIN_REQUEST
jb @f
lea ecx, [eax + CHUNK_OVERHEAD + CHUNK_ALIGN_MASK]
and ecx, not CHUNK_ALIGN_MASK
@@:
mov esi, ecx
shr ecx, SMALLBIN_SHIFT
mov eax, [ebp + malloc_state.smallmap]
shr eax, cl
test eax, 3
jz .small.remainder
; Remainderless fit to a smallbin.
shr eax, 1
sbb ecx, -1 ; Uses next bin if idx empty
lea edx, [ebp + malloc_state.smallbins + ecx*8]
mov eax, [ebp + malloc_state.smallbins + ecx*8 + mchunk_fd]
unlink_first_small_chunk ; ebp, edx, eax, ecx
lea edx, [ecx*SMALLBIN_WIDTH+PINUSE_BIT+CINUSE_BIT]
mov [eax+mchunk_head], edx
or dword [eax+ecx*SMALLBIN_WIDTH+mchunk_head], PINUSE_BIT
mark_inuse_foot eax+ecx*SMALLBIN_WIDTH
unlock_heap
ret
.small.remainder:
cmp esi, [ebp+malloc_state.dvsize]
jbe .use_dv_chunk
test eax, eax
jz .small.try_split_large
bsf eax, eax
add ecx, eax
lea edx, [ebp + malloc_state.smallbins + ecx*8]
mov eax, [ebp + malloc_state.smallbins + ecx*8 + mchunk_fd]
unlink_first_small_chunk ; ebp, edx, eax, ecx
lea edx, [esi+PINUSE_BIT+CINUSE_BIT]
mov [eax+mchunk_head], edx
lea edx, [eax+esi]
shl ecx, SMALLBIN_SHIFT
sub ecx, esi
mark_inuse_foot edx
lea ebx, [ecx+PINUSE_BIT]
mov [edx+mchunk_head], ebx
mov [edx+ecx+mchunk_prev_foot], ecx
replace_dv ; ebp, ecx, edx
unlock_heap
ret
.use_dv_chunk:
mov ecx, [ebp+malloc_state.dvsize]
mov eax, [ebp+malloc_state.dv]
sub ecx, esi
cmp [ebp+malloc_state.dvsize], NSMALLBINS shl SMALLBIN_SHIFT
jb @f
cmp ecx, NSMALLBINS shl SMALLBIN_SHIFT
jae @f
lea edx, [eax+esi]
add edx, ecx
mov ebx, [edx+tchunk_release_fd]
cmp [ebx+tchunk_release_bk], edx
jnz heap_corrupted
mov ebx, [edx+tchunk_release_bk]
cmp [ebx+tchunk_release_fd], edx
jnz heap_corrupted
mov edx, [edx+tchunk_release_fd]
mov [ebx+tchunk_release_fd], edx
mov [edx+tchunk_release_bk], ebx
@@:
cmp ecx, MIN_CHUNK_SIZE
jb .no_new_chunk_dv
lea edx, [eax+esi]
mov [ebp+malloc_state.dv], edx
mov [ebp+malloc_state.dvsize], ecx
lea ebx, [ecx+PINUSE_BIT]
mov [edx+mchunk_head], ebx
mov [edx+ecx+mchunk_prev_foot], ecx
lea ebx, [esi+PINUSE_BIT+CINUSE_BIT]
mov [eax+mchunk_head], ebx
mark_inuse_foot edx
unlock_heap
ret
.no_new_chunk_dv:
add ecx, esi
mov [ebp+malloc_state.dv], 0
mov [ebp+malloc_state.dvsize], 0
lea ebx, [ecx+PINUSE_BIT+CINUSE_BIT]
mov [eax+mchunk_head], ebx
or dword [eax+ecx+mchunk_head], PINUSE_BIT
mark_inuse_foot eax+ecx
unlock_heap
ret
.small.try_split_large:
cmp [ebp+malloc_state.treemap], 0
jz .from_top_or_sys
tmalloc_small_and_return
.large:
cmp eax, MAX_REQUEST
jae .fail
lea esi, [eax + CHUNK_OVERHEAD + CHUNK_ALIGN_MASK]
and esi, not CHUNK_ALIGN_MASK
cmp [ebp+malloc_state.treemap], 0
jz .from_dv_top_or_sys
tmalloc_large_and_return ; can fail
.from_dv_top_or_sys:
cmp esi, [ebp+malloc_state.dvsize]
jbe .use_dv_chunk
.from_top_or_sys:
; Directly map large chunks
cmp esi, [ebp+malloc_state.mmap_threshold]
jb @f
mov ecx, esi
call mmap_alloc
test eax, eax
jz @f
unlock_heap
ret
@@:
cmp esi, [ebp+malloc_state.topsize]
jae .from_sys
mov eax, [ebp+malloc_state.top]
mov ecx, [ebp+malloc_state.topsize]
lea edx, [eax+esi]
sub ecx, esi
mov [ebp+malloc_state.top], edx
cmp edx, [ebp+malloc_state.topmax]
jb @f
mov [ebp+malloc_state.topmax], edx
@@:
mov [ebp+malloc_state.topsize], ecx
lea ebx, [ecx+PINUSE_BIT]
mov [edx+mchunk_head], ebx
lea ebx, [esi+PINUSE_BIT+CINUSE_BIT]
mov [eax+mchunk_head], ebx
mark_inuse_foot edx
unlock_heap
ret
.from_sys:
call sys_alloc
unlock_heap
ret
.fail:
mov FS_ERRNO, ENOMEM
xor eax, eax
unlock_heap
ret
}
; ---------------------------- free ---------------------------
; in: ebp -> malloc_state
; in: [mem] = stack var with pointer to free
macro do_free
{
; Consolidate freed chunks with preceeding or succeeding bordering
; free chunks, if they exist, and then place in a bin. Intermixed
; with special cases for top, dv, mmapped chunks, and usage errors.
cmp [mem], 0
jz .nothing
if FOOTERS
mov ecx, [mem]
mov eax, [ecx+mchunk_head]
and eax, not FLAG_BITS
mov eax, [ecx+eax+mchunk_prev_foot]
xor eax, [malloc_magic]
cmp eax, ebp
jnz heap_corrupted
end if
lock_heap
mov eax, [mem]
mov ecx, [eax+mchunk_head]
mov edx, ecx
and ecx, INUSE_BITS
assert PINUSE_BIT = 1
assert CINUSE_BIT = 2
; Possible values of ecx:
; 0 = mmapped chunk, should be rare
; 1 = illegal, trying to double-free
; 2 = previous chunk is not in use, merge backwards
; 3 = previous chunk is in use, no merge backwards
and edx, not FLAG_BITS
cmp ecx, 2
ja .see_forward
jb .free_mmapped
; turn CINUSE_BIT to PINUSE_BIT, increase chances to detect double-free
dec dword [eax+mchunk_head]
cmp dword [eax+mchunk_prev_foot], NSMALLBINS shl SMALLBIN_SHIFT
jb @f
mov ebx, [eax+tchunk_release_fd]
mov ecx, [eax+tchunk_release_bk]
cmp [ebx+tchunk_release_bk], eax
jnz heap_corrupted
cmp [ecx+tchunk_release_fd], eax
jnz heap_corrupted
mov [ebx+tchunk_release_bk], ecx
mov [ecx+tchunk_release_fd], ebx
@@:
mov ecx, [eax+mchunk_prev_foot]
add edx, [eax+mchunk_prev_foot]
sub eax, [eax+mchunk_prev_foot]
cmp eax, [ebp+malloc_state.dv]
jz .append_dv
push edx
mov edx, ecx
unlink_chunk ; ebp, eax, edx
pop edx
.see_forward:
mov esi, eax
assert PINUSE_BIT = 1
btr dword [eax+edx+mchunk_head], 0
jnc heap_corrupted
test dword [eax+edx+mchunk_head], CINUSE_BIT
jnz .consolidated
.consolidate_forward:
add eax, edx
cmp eax, [ebp+malloc_state.top]
jz .prepend_top
cmp eax, [ebp+malloc_state.dv]
jz .prepend_dv
push esi edx
mov edx, [eax+mchunk_head]
and edx, not FLAG_BITS
add [esp], edx
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jae .consolidate_large
unlink_small_chunk ; ebp, eax, edx
jmp .consolidate_common
.consolidate_large:
lea ecx, [eax+edx]
mov ebx, [eax+edx+tchunk_release_fd]
mov edx, [eax+edx+tchunk_release_bk]
cmp [ebx+tchunk_release_bk], ecx
jnz heap_corrupted
cmp [edx+tchunk_release_fd], ecx
jnz heap_corrupted
mov [ebx+tchunk_release_bk], edx
mov [edx+tchunk_release_fd], ebx
unlink_large_chunk ; ebp, eax
.consolidate_common:
pop edx esi
cmp esi, [ebp+malloc_state.dv]
jz .dv_consolidated
.consolidated:
lea ecx, [edx+PINUSE_BIT]
mov [esi+mchunk_head], ecx
mov [esi+edx+mchunk_prev_foot], edx
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jae .large
insert_small_chunk ; ebp, esi, edx
unlock_heap
.nothing:
ret
.large:
lea ecx, [esi+edx]
lea eax, [ebp+malloc_state.release_list-tchunk_release_fd]
mov ebx, [ebp+malloc_state.release_list]
cmp [ebx+tchunk_release_bk], eax
jnz heap_corrupted
mov [ecx+tchunk_release_fd], ebx
mov [ecx+tchunk_release_bk], eax
mov [ebx+tchunk_release_bk], ecx
mov [eax+tchunk_release_fd], ecx
@@:
push edi
macro trim_ret \{
trim_if_should
unlock_heap
pop edi
ret
\}
insert_large_chunk trim_ret ; ebp, esi, edx
purge trim_ret
.dv_consolidated:
mov [esi+edx+mchunk_prev_foot], edx
mov [ebp+malloc_state.dvsize], edx
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jb @f
lea ecx, [esi+edx]
lea eax, [ebp+malloc_state.release_list-tchunk_release_fd]
mov ebx, [ebp+malloc_state.release_list]
cmp [ebx+tchunk_release_bk], eax
jnz heap_corrupted
mov [ecx+tchunk_release_fd], ebx
mov [ecx+tchunk_release_bk], eax
mov [ebx+tchunk_release_bk], ecx
mov [eax+tchunk_release_fd], ecx
@@:
assert PINUSE_BIT = 1
inc edx
mov [esi+mchunk_head], edx
unlock_heap
ret
.append_dv:
mov esi, eax
assert PINUSE_BIT = 1
btr dword [eax+edx+mchunk_head], 0
jnc heap_corrupted
test dword [eax+edx+mchunk_head], CINUSE_BIT
jz .consolidate_forward
mov [ebp+malloc_state.dvsize], edx
lea ecx, [edx+PINUSE_BIT]
mov [eax+mchunk_head], ecx
mov [eax+edx+mchunk_prev_foot], edx
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jb @f
add edx, eax
lea eax, [ebp+malloc_state.release_list-tchunk_release_fd]
mov ebx, [ebp+malloc_state.release_list]
cmp [ebx+tchunk_release_bk], eax
jnz heap_corrupted
mov [edx+tchunk_release_fd], ebx
mov [edx+tchunk_release_bk], eax
mov [ebx+tchunk_release_bk], edx
mov [eax+tchunk_release_fd], edx
@@:
unlock_heap
ret
.prepend_dv:
add edx, [ebp+malloc_state.dvsize]
cmp [ebp+malloc_state.dvsize], NSMALLBINS shl SMALLBIN_SHIFT
jb @f
lea ecx, [esi+edx]
mov eax, [esi+edx+tchunk_release_fd]
mov ebx, [esi+edx+tchunk_release_bk]
cmp [eax+tchunk_release_bk], ecx
jnz heap_corrupted
cmp [ebx+tchunk_release_fd], ecx
jnz heap_corrupted
mov [eax+tchunk_release_bk], ebx
mov [ebx+tchunk_release_fd], eax
@@:
mov [ebp+malloc_state.dvsize], edx
mov [ebp+malloc_state.dv], esi
mov [esi+edx+mchunk_prev_foot], edx
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jb @f
lea ecx, [esi+edx]
lea eax, [ebp+malloc_state.release_list-tchunk_release_fd]
mov ebx, [ebp+malloc_state.release_list]
cmp [ebx+tchunk_release_bk], eax
jnz heap_corrupted
mov [ecx+tchunk_release_fd], ebx
mov [ecx+tchunk_release_bk], eax
mov [ebx+tchunk_release_bk], ecx
mov [eax+tchunk_release_fd], ecx
@@:
assert PINUSE_BIT = 1
inc edx
mov [esi+mchunk_head], edx
unlock_heap
ret
.prepend_top:
add edx, [ebp+malloc_state.topsize]
mov [ebp+malloc_state.topsize], edx
mov [ebp+malloc_state.top], esi
assert PINUSE_BIT = 1
inc edx
mov [esi+mchunk_head], edx
cmp esi, [ebp+malloc_state.dv]
jnz @f
mov [ebp+malloc_state.dv], 0
mov [ebp+malloc_state.dvsize], 0
@@:
trim_if_should
unlock_heap
ret
.free_mmapped:
dec ecx
jz heap_corrupted
mov ecx, eax
add edx, [eax+mchunk_prev_foot]
add edx, MMAP_FOOT_PAD-8
test edx, 0xFFF
jnz heap_corrupted
sub [ebp+malloc_state.footprint], edx
sub ecx, [ecx+mchunk_prev_foot]
test ecx, 0xFFF
jnz heap_corrupted
mov eax, [ecx]
mov ebx, [ecx+4]
cmp [eax+4], ecx
jnz heap_corrupted
cmp [ebx], ecx
jnz heap_corrupted
mov [eax+4], ebx
mov [ebx], eax
mov eax, 68
mov ebx, 13
call FS_SYSCALL_PTR
unlock_heap
ret
}
; in: ebp -> malloc_state
; in: [n_elements] = stack var with number of elements
; in: [elem_size] = stack var with element size
macro do_calloc malloc_call
{
mov eax, [n_elements]
mul [elem_size]
test edx, edx
jnz .fail
mov [n_elements], eax
malloc_call
test eax, eax
jz .nothing
test dword [eax+mchunk_head], INUSE_BITS
jz .nothing
push eax edi
mov edi, eax
mov ecx, [n_elements]
add ecx, 3
shr ecx, 2
xor eax, eax
rep stosd
pop edi eax
.nothing:
ret
.fail:
mov FS_ERRNO, ENOMEM
xor eax, eax
ret
}
; ------------ Internal support for realloc, memalign, etc --------------
; Try to realloc; only in-place unless can_move true
; in: ebp -> malloc_state
; in: [oldmem] = stack var with pointer to realloc
; in: [bytes] = stack var with number of bytes to allocate
macro try_realloc_chunk can_move
{
lock_heap
mov eax, [oldmem]
mov ecx, MIN_CHUNK_SIZE
cmp [bytes], MIN_REQUEST
jb @f
mov ecx, [bytes]
add ecx, CHUNK_OVERHEAD + CHUNK_ALIGN_MASK
and ecx, not CHUNK_ALIGN_MASK
@@:
mov [bytes], ecx
mov edx, [eax+mchunk_head]
and edx, not FLAG_BITS
; Possible values of [eax+mchunk_head] and INUSE_BIT:
; 0 = mmapped chunk, should be rare
; 1 = illegal, trying to realloc already-freed chunk
; 2,3 = normal chunk
test dword [eax+mchunk_head], CINUSE_BIT
jz .mmapped
test dword [eax+edx+mchunk_head], PINUSE_BIT
jz heap_corrupted
cmp ecx, edx
jbe .realloc_decrease
add eax, edx
cmp eax, [ebp+malloc_state.top]
jz .move_top
cmp eax, [ebp+malloc_state.dv]
jz .extend_into_dv
test dword [eax+mchunk_head], CINUSE_BIT
jnz .failed
; extend into next free chunk
push edx
mov edx, [eax+mchunk_head]
and edx, not FLAG_BITS
add [esp], edx
sub [esp], ecx
jb .failed_pop
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jae .large
unlink_small_chunk ; ebp, eax, edx
jmp .common
.large:
cmp dword [esp], NSMALLBINS shl SMALLBIN_SHIFT
jae @f
lea ecx, [eax+edx]
mov ebx, [eax+edx+tchunk_release_fd]
mov edx, [eax+edx+tchunk_release_bk]
cmp [ebx+tchunk_release_bk], ecx
jnz heap_corrupted
cmp [edx+tchunk_release_fd], ecx
jnz heap_corrupted
mov [ebx+tchunk_release_bk], edx
mov [edx+tchunk_release_fd], ebx
@@:
unlink_large_chunk ; ebp, eax
.common:
pop edx
mov eax, [oldmem]
mov ecx, [bytes]
cmp edx, MIN_CHUNK_SIZE
jae .add_chunk
.no_new_chunk:
add edx, ecx
mov ebx, [eax+mchunk_head]
and ebx, PINUSE_BIT
lea ebx, [edx+ebx+CINUSE_BIT]
mov [eax+mchunk_head], ebx
or dword [eax+edx+mchunk_head], PINUSE_BIT
mark_inuse_foot eax+edx
.nothing:
unlock_heap
ret
.realloc_decrease:
test dword [eax+edx+mchunk_head], CINUSE_BIT
jz .prepend_free
sub edx, ecx
cmp edx, MIN_CHUNK_SIZE
jb .nothing
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jb .add_chunk
lea ebx, [eax+ecx]
add ebx, edx
lea eax, [ebp+malloc_state.release_list-tchunk_release_fd]
mov esi, [ebp+malloc_state.release_list]
cmp [esi+tchunk_release_bk], eax
jnz heap_corrupted
mov [ebx+tchunk_release_fd], esi
mov [ebx+tchunk_release_bk], eax
mov [esi+tchunk_release_bk], ebx
mov [eax+tchunk_release_fd], ebx
mov eax, [oldmem]
.add_chunk:
mov ebx, [eax+mchunk_head]
lea esi, [eax+ecx]
and ebx, PINUSE_BIT
lea ebx, [ecx+ebx+CINUSE_BIT]
mov [eax+mchunk_head], ebx
mark_inuse_foot esi
lea ecx, [edx+PINUSE_BIT]
mov [esi+mchunk_head], ecx
mov [esi+edx+mchunk_prev_foot], edx
and dword [esi+edx+mchunk_head], not PINUSE_BIT
push edi
macro unlock_ret \{
pop edi
unlock_heap
ret
\}
insert_chunk unlock_ret ; ebp, esi, edx
purge unlock_ret
.prepend_free:
add eax, edx
cmp eax, [ebp+malloc_state.top]
jz .move_top
cmp eax, [ebp+malloc_state.dv]
jz .prepend_dv
sub edx, ecx
push edx
mov edx, [eax+mchunk_head]
and edx, not FLAG_BITS
add [esp], edx
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jae .prepend_old_large
unlink_small_chunk ; ebp, eax, edx
jmp .prepend_old_common
.prepend_old_large:
add edx, eax
mov ebx, [edx+tchunk_release_fd]
mov ecx, [edx+tchunk_release_bk]
cmp [ebx+tchunk_release_bk], edx
jnz heap_corrupted
cmp [ecx+tchunk_release_fd], edx
jnz heap_corrupted
mov [ebx+tchunk_release_bk], ecx
mov [ecx+tchunk_release_fd], ebx
unlink_large_chunk ; ebp, eax
.prepend_old_common:
pop edx
mov esi, [oldmem]
add esi, [bytes]
mov [esi+edx+mchunk_prev_foot], edx
lea ecx, [edx+PINUSE_BIT]
mov [esi+mchunk_head], ecx
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jb .prepend_new_small
lea ecx, [esi+edx]
lea eax, [ebp+malloc_state.release_list-tchunk_release_fd]
mov ebx, [ebp+malloc_state.release_list]
cmp [ebx+tchunk_release_bk], eax
jnz heap_corrupted
mov [eax+tchunk_release_fd], ecx
mov [ebx+tchunk_release_bk], ecx
mov [ecx+tchunk_release_fd], ebx
mov [ecx+tchunk_release_bk], eax
push edi
macro after_insert \{
pop edi
jmp .prepend_new_common
\}
insert_large_chunk after_insert ; ebp, esi, edx
purge after_insert
.prepend_new_small:
insert_small_chunk ; ebp, esi, edx
.prepend_new_common:
mov eax, [oldmem]
mov ecx, [bytes]
mark_inuse_foot eax+ecx
mov ebx, [eax+mchunk_head]
and ebx, PINUSE_BIT
lea ebx, [ebx+ecx+CINUSE_BIT]
mov [eax+mchunk_head], ebx
unlock_heap
ret
.prepend_dv:
add edx, [ebp+malloc_state.dvsize]
add eax, [ebp+malloc_state.dvsize]
sub edx, ecx
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jb .move_dv
cmp [ebp+malloc_state.dvsize], NSMALLBINS shl SMALLBIN_SHIFT
jb @f
cmp [eax+tchunk_release_fd], eax
jnz .move_dv
@@:
lea ebx, [ebp+malloc_state.release_list-tchunk_release_fd]
mov esi, [ebp+malloc_state.release_list]
cmp [esi+tchunk_release_bk], ebx
jnz heap_corrupted
mov [eax+tchunk_release_fd], esi
mov [eax+tchunk_release_bk], ebx
mov [esi+tchunk_release_bk], eax
mov [ebx+tchunk_release_fd], eax
jmp .move_dv
.extend_into_dv:
add edx, [ebp+malloc_state.dvsize]
sub edx, ecx
jb .failed
cmp [ebp+malloc_state.dvsize], NSMALLBINS shl SMALLBIN_SHIFT
jb .move_dv
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jae .move_dv
add eax, [ebp+malloc_state.dvsize]
mov ebx, [eax+tchunk_release_fd]
mov esi, [eax+tchunk_release_bk]
cmp [ebx+tchunk_release_bk], eax
jnz heap_corrupted
cmp [esi+tchunk_release_fd], eax
jnz heap_corrupted
mov [ebx+tchunk_release_bk], esi
mov [esi+tchunk_release_fd], ebx
.move_dv:
mov eax, [oldmem]
cmp edx, MIN_CHUNK_SIZE
jb .dv_no_new_chunk
mov ebx, [eax+mchunk_head]
and ebx, PINUSE_BIT
lea ebx, [ecx+ebx+CINUSE_BIT]
mov [eax+mchunk_head], ebx
add ecx, eax
mark_inuse_foot ecx
lea ebx, [edx+PINUSE_BIT]
mov [ecx+mchunk_head], ebx
mov [ecx+edx+mchunk_prev_foot], edx
and dword [ecx+edx+mchunk_head], not PINUSE_BIT
mov [ebp+malloc_state.dvsize], edx
mov [ebp+malloc_state.dv], ecx
unlock_heap
ret
.dv_no_new_chunk:
add edx, ecx
mov ebx, [eax+mchunk_head]
and ebx, PINUSE_BIT
lea ebx, [edx+ebx+CINUSE_BIT]
mov [eax+mchunk_head], ebx
or dword [eax+edx+mchunk_head], PINUSE_BIT
mark_inuse_foot eax+edx
mov [ebp+malloc_state.dvsize], 0
mov [ebp+malloc_state.dv], 0
unlock_heap
ret
.move_top:
add edx, [ebp+malloc_state.topsize]
sub edx, ecx
jbe .failed
mov eax, [oldmem]
mov ebx, [eax+mchunk_head]
and ebx, PINUSE_BIT
lea ebx, [ecx+ebx+CINUSE_BIT]
mov [eax+mchunk_head], ebx
add ecx, eax
mark_inuse_foot ecx
mov [ebp+malloc_state.top], ecx
mov [ebp+malloc_state.topsize], edx
assert PINUSE_BIT = 1
inc edx
mov [ecx+mchunk_head], edx
unlock_heap
ret
.mmapped:
test dword [eax+mchunk_head], PINUSE_BIT
jnz heap_corrupted
mov edx, eax
if can_move
mov ebx, 1
else
xor ebx, ebx
end if
call mmap_resize
test eax, eax
jz .failed
unlock_heap
ret
.failed_pop:
pop edx
.failed:
unlock_heap
}
; ------------------ Exported realloc, memalign, etc --------------------
; in: ebp -> malloc_state
; in: [oldmem] = stack var with pointer to realloc
; in: [bytes] = stack var with number of bytes to allocate
macro do_realloc malloc_call, free_call
{
cmp [oldmem], 0
jz .malloc
cmp [bytes], 0
jz .free
cmp [bytes], MAX_REQUEST
jae .fail
if FOOTERS
mov ecx, [oldmem]
mov eax, [ecx+mchunk_head]
and eax, not FLAG_BITS
mov eax, [ecx+eax+mchunk_prev_foot]
xor eax, [malloc_magic]
cmp eax, ebp
jnz heap_corrupted
end if
try_realloc_chunk 1 ; ebp, [oldmem], [bytes]
sub [bytes], CHUNK_OVERHEAD ; try_realloc_chunk has padded [bytes]
malloc_call [bytes]
test eax, eax
jz .justret
mov esi, [oldmem]
push eax
push edi
mov ecx, [esi+mchunk_head]
mov edi, eax
mov edx, MMAP_CHUNK_OVERHEAD
test ecx, INUSE_BITS
jz @f
mov edx, CHUNK_OVERHEAD
@@:
and ecx, not FLAG_BITS
sub ecx, edx
cmp ecx, [bytes+8]
jb @f
mov ecx, [bytes+8]
@@:
shr ecx, 2
rep movsd
pop edi
free_call [oldmem+4]
pop eax
.justret:
ret
.malloc:
malloc_call [bytes]
ret
.free:
free_call [oldmem]
xor eax, eax
ret
.fail:
mov FS_ERRNO, ENOMEM
xor eax, eax
ret
}
; in: ebp -> malloc_state
; in: [oldmem] = stack var with pointer to realloc
; in: [bytes] = stack var with number of bytes to allocate
macro do_realloc_in_place
{
cmp [oldmem], 0
jz .fail
cmp [bytes], MAX_REQUEST
jae .fail
if FOOTERS
mov ecx, [oldmem]
mov eax, [ecx+mchunk_head]
and eax, not FLAG_BITS
mov eax, [ecx+eax+mchunk_prev_foot]
xor eax, [malloc_magic]
cmp eax, ebp
jnz heap_corrupted
end if
try_realloc_chunk 0 ; ebp, [oldmem], [bytes]
.fail:
xor eax, eax
ret
}
; in: ebp -> malloc_state
; in: [alignment] = stack var with required alignment
; in: [bytes] = stack var with number of bytes to allocate
macro do_memalign malloc_call
{
mov eax, [alignment]
cmp [alignment], MALLOC_ALIGNMENT
jbe .just_malloc
lea edx, [eax-1]
cmp eax, MIN_CHUNK_SIZE
jb .set_to_min_chunk_size
test eax, edx
jnz .set_align_pow2
.alignment_ok:
add eax, [bytes]
jc .too_large
cmp eax, MAX_REQUEST
jae .too_large
mov ecx, MIN_CHUNK_SIZE
cmp [bytes], MIN_REQUEST
jb @f
mov ecx, [bytes]
add ecx, CHUNK_OVERHEAD + CHUNK_ALIGN_MASK
and ecx, not CHUNK_ALIGN_MASK
@@:
mov [bytes], ecx
add ecx, [alignment]
add ecx, MIN_CHUNK_SIZE - CHUNK_OVERHEAD
malloc_call ecx
test eax, eax
jz .nothing
mov esi, eax
lock_heap
mov eax, esi
mov edx, [alignment]
dec edx
test esi, edx
jz .aligned
; Find an aligned spot inside chunk. Since we need to give
; back leading space in a chunk of at least MIN_CHUNK_SIZE, if
; the first calculation places us at a spot with less than
; MIN_CHUNK_SIZE leader, we can move to the next aligned spot.
; We've allocated enough total room so that this is always
; possible.
not edx
lea eax, [esi-1]
add eax, [alignment]
and eax, edx
mov edx, eax
sub edx, esi
cmp edx, MIN_CHUNK_SIZE
jae @f
add eax, [alignment]
add edx, [alignment]
@@:
test dword [esi+mchunk_head], INUSE_BITS
jz .unaligned_mmapped
; give back leader, use the rest
mov ecx, [esi+mchunk_head]
and ecx, not FLAG_BITS
sub ecx, edx
mark_inuse_foot eax+ecx
or ecx, CINUSE_BIT
mov [eax+mchunk_head], ecx
test dword [esi+mchunk_head], PINUSE_BIT
jnz .insert_before
mov ebx, esi
mov edx, [esi+mchunk_prev_foot]
sub esi, [esi+mchunk_prev_foot]
cmp esi, [ebp+malloc_state.dv]
jz .append_dv
push eax
mov eax, esi
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jae .append_large
unlink_small_chunk ; ebp, eax, edx
jmp .append_common
.append_large:
mov ecx, [ebx+tchunk_release_fd]
mov esi, [ebx+tchunk_release_bk]
cmp [ecx+tchunk_release_bk], ebx
jnz heap_corrupted
cmp [esi+tchunk_release_fd], ebx
jnz heap_corrupted
mov [ecx+tchunk_release_bk], esi
mov [esi+tchunk_release_fd], ecx
unlink_large_chunk ; ebp, eax
.append_common:
mov esi, eax
mov edx, [esp]
pop eax
sub edx, esi
.insert_before:
lea ecx, [edx+PINUSE_BIT]
mov [esi+mchunk_head], ecx
mov [eax+mchunk_prev_foot], edx
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jb .small_before
lea ebx, [ebp+malloc_state.release_list-tchunk_release_fd]
mov ecx, [ebp+malloc_state.release_list]
cmp [ecx+tchunk_release_bk], ebx
jnz heap_corrupted
mov [ebx+tchunk_release_fd], eax
mov [ecx+tchunk_release_bk], eax
mov [eax+tchunk_release_fd], ecx
mov [eax+tchunk_release_bk], ebx
push edi
macro after_insert label \{
pop edi
jmp label
\}
insert_large_chunk <after_insert .common_before> ; ebp, esi, edx
.small_before:
insert_small_chunk ; ebp, esi, edx
.common_before:
.aligned:
; give back spare room at the end
test dword [eax+mchunk_head], INUSE_BITS
jz .done_after
mov ecx, [bytes]
mov edx, [eax+mchunk_head]
mov ebx, edx
and edx, not FLAG_BITS
lea esi, [eax+ecx]
sub edx, ecx
test dword [esi+edx+mchunk_head], CINUSE_BIT
jz @f
cmp edx, MIN_CHUNK_SIZE
jb .done_after
@@:
and ebx, INUSE_BITS
add ebx, ecx
mov [eax+mchunk_head], ebx
mark_inuse_foot esi
test dword [esi+edx+mchunk_head], CINUSE_BIT
jnz .insert_after
add esi, edx
cmp esi, [ebp+malloc_state.dv]
jz .prepend_dv
cmp esi, [ebp+malloc_state.top]
jz .prepend_top
mov edx, [esi+mchunk_head]
and edx, not FLAG_BITS
push eax
mov eax, esi
add esi, edx
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jae .prepend_large
unlink_small_chunk ; ebp, eax, edx
jmp .prepend_common
.prepend_large:
mov ecx, [esi+tchunk_release_fd]
mov ebx, [esi+tchunk_release_bk]
cmp [ecx+tchunk_release_bk], esi
jnz heap_corrupted
cmp [ebx+tchunk_release_fd], esi
jnz heap_corrupted
mov [ecx+tchunk_release_bk], ebx
mov [ebx+tchunk_release_fd], ecx
mov ecx, esi
unlink_large_chunk ; ebp, eax
mov esi, ecx
.prepend_common:
pop eax
mov edx, esi
mov esi, [bytes]
add esi, eax
sub edx, esi
.insert_after:
lea ebx, [edx+PINUSE_BIT]
mov [esi+mchunk_head], ebx
mov [esi+edx+mchunk_prev_foot], edx
and dword [esi+edx+mchunk_head], not PINUSE_BIT
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jb .small_after
push edi
lea ebx, [ebp+malloc_state.release_list-tchunk_release_fd]
mov ecx, [ebp+malloc_state.release_list]
lea edi, [esi+edx]
cmp [ecx+tchunk_release_bk], ebx
jnz heap_corrupted
mov [ebx+tchunk_release_fd], edi
mov [ecx+tchunk_release_bk], edi
mov [edi+tchunk_release_fd], ecx
mov [edi+tchunk_release_bk], ebx
insert_large_chunk <after_insert .done_after> ; ebp, esi, edx
purge after_insert
.small_after:
insert_small_chunk ; ebp, esi, edx
.done_after:
unlock_heap
ret
.prepend_dv:
sub esi, edx
add edx, [ebp+malloc_state.dvsize]
mov [ebp+malloc_state.dv], esi
lea ecx, [edx+PINUSE_BIT]
mov [esi+mchunk_head], ecx
mov [esi+edx+mchunk_prev_foot], edx
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jb .prepend_dv.norelease
add esi, edx
cmp [ebp+malloc_state.dvsize], NSMALLBINS shl SMALLBIN_SHIFT
jb @f
cmp [esi+tchunk_release_fd], esi
jnz .prepend_dv.norelease
@@:
lea ebx, [ebp+malloc_state.release_list-tchunk_release_fd]
mov ecx, [ebp+malloc_state.release_list]
cmp [ecx+tchunk_release_bk], ebx
jnz heap_corrupted
mov [ebx+tchunk_release_fd], esi
mov [ecx+tchunk_release_bk], esi
mov [esi+tchunk_release_fd], ecx
mov [esi+tchunk_release_bk], ebx
.prepend_dv.norelease:
mov [ebp+malloc_state.dvsize], edx
unlock_heap
ret
.prepend_top:
sub esi, edx
mov [ebp+malloc_state.top], esi
add edx, [ebp+malloc_state.topsize]
mov [ebp+malloc_state.topsize], edx
assert PINUSE_BIT = 1
inc edx
mov [esi+mchunk_head], edx
unlock_heap
ret
.append_dv:
mov edx, eax
sub edx, esi
cmp edx, NSMALLBINS shl SMALLBIN_SHIFT
jb .append_dv.norelease
cmp [ebp+malloc_state.dvsize], NSMALLBINS shl SMALLBIN_SHIFT
jb @f
cmp [eax+tchunk_release_fd], eax
jnz .append_dv.norelease
@@:
lea ebx, [ebp+malloc_state.release_list-tchunk_release_fd]
mov ecx, [ebp+malloc_state.release_list]
cmp [ecx+tchunk_release_bk], ebx
jnz heap_corrupted
mov [ebx+tchunk_release_fd], eax
mov [ecx+tchunk_release_bk], eax
mov [eax+tchunk_release_fd], ecx
mov [eax+tchunk_release_bk], ebx
.append_dv.norelease:
lea ecx, [edx+PINUSE_BIT]
mov [ebp+malloc_state.dvsize], edx
mov [eax+mchunk_prev_foot], edx
mov [esi+mchunk_head], ecx
jmp .common_before
.unaligned_mmapped:
; For mmapped chunks, just adjust offset
mov ecx, [esi+mchunk_head]
sub ecx, edx
add edx, [esi+mchunk_prev_foot]
mov [eax+mchunk_prev_foot], edx
mov [eax+mchunk_head], ecx
unlock_heap
ret
.too_large:
mov FS_ERRNO, ENOMEM
xor eax, eax
.nothing:
ret
.set_to_min_chunk_size:
mov eax, MIN_CHUNK_SIZE
mov [alignment], eax
jmp .alignment_ok
.set_align_pow2:
bsr ecx, eax
mov eax, 2
shl eax, cl
mov [alignment], eax
jmp .alignment_ok
.just_malloc:
malloc_call [bytes]
ret
}
macro do_malloc_trim
{
ret
}
macro do_malloc_footprint
{
mov eax, [ebp+malloc_state.footprint]
ret
}
macro do_malloc_max_footprint
{
mov eax, [ebp+malloc_state.max_footprint]
ret
}
macro do_malloc_footprint_limit
{
mov eax, [ebp+malloc_state.footprint_limit]
test eax, eax
jnz @f
dec eax
@@:
ret
}
macro do_malloc_set_footprint_limit
{
mov eax, [bytes]
test eax, eax
jnz @f
inc eax
@@:
cmp eax, -1
jnz @f
inc eax
@@:
add eax, 0xFFF
and eax, not 0xFFF
mov [ebp+malloc_state.footprint_limit], eax
ret
}
macro do_mspace_mallopt
{
}
; ----------------------------- user mspaces ----------------------------
malloc_state_chunk_size = (sizeof.malloc_state + CHUNK_OVERHEAD + CHUNK_ALIGN_MASK) and not CHUNK_ALIGN_MASK
macro init_user_mstate
{
mov ebx, eax
add eax, 8 + ((-8) and CHUNK_ALIGN_MASK)
mov dword [eax+mchunk_head], malloc_state_chunk_size + INUSE_BITS
mov [eax+malloc_state.mmap_threshold], DEFAULT_MMAP_THRESHOLD
mov [eax+malloc_state.seg.base], ebx
mov [eax+malloc_state.seg.size], ecx
mov [eax+malloc_state.segment_size], ecx
mov [eax+malloc_state.footprint], ecx
mov [eax+malloc_state.max_footprint], ecx
lea ecx, [ecx+ebx+8-TOP_FOOT_SIZE]
if FOOTERS
mov ebx, [malloc_magic]
mov [eax+malloc_state.magic], ebx
end if
mov [eax+malloc_state.release_checks], RELEASE_CHECK_RATE
init_bins ; eax
lea ebx, [eax+malloc_state.release_list-tchunk_release_fd]
mov [eax+malloc_state.release_list+0], ebx
mov [eax+malloc_state.release_list+4], ebx
lea ebx, [eax+malloc_state.mmap_list]
mov [eax+malloc_state.mmap_list], ebx
mov [eax+malloc_state.mmap_list+4], ebx
lea ebx, [eax+malloc_state_chunk_size]
sub ecx, ebx
init_top ; eax, ebx, ecx
}
; in: [capacity] = stack var with number of bytes to allocate
; in: [locked] = stack var which is zero if locking is not needed
; out: eax -> allocated data
macro do_create_mspace
{
mov eax, 68
mov ebx, 12
mov ecx, [capacity]
test ecx, ecx
jnz @f
mov ecx, DEFAULT_MSPACE_SIZE
@@:
add ecx, 0xFFF
and ecx, not 0xFFF
jz .fail
call FS_SYSCALL_PTR
test eax, eax
jz .fail
init_user_mstate
and [eax+malloc_state.mflags], not USE_LOCK_BIT
cmp [locked], 0
jz @f
or [eax+malloc_state.mflags], USE_LOCK_BIT
@@:
ret
.fail:
xor eax, eax
ret
}
; in: [msp] = stack var with mspace to free
macro do_destroy_mspace
{
mov edx, [msp]
if FOOTERS
mov ebx, [malloc_magic]
cmp [edx+malloc_state.magic], ebx
jnz heap_corrupted
end if
add edx, malloc_state.mmap_list
push edx
mov ecx, [edx]
cmp ecx, [esp]
jz .large_done
@@:
mov eax, 68
mov ebx, 13
mov edx, [ecx]
call FS_SYSCALL_PTR
mov ecx, edx
cmp edx, [esp]
jnz @b
.large_done:
pop edx
add edx, malloc_state.seg - malloc_state.mmap_list
.free_segments:
mov eax, 68
mov ebx, 13
mov ecx, [edx+malloc_segment.base]
mov edx, [edx+malloc_segment.next]
call FS_SYSCALL_PTR
test edx, edx
jnz .free_segments
ret
}
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