circuitpython/supervisor/shared/memory.c

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2018 Scott Shawcroft for Adafruit Industries
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "supervisor/memory.h"
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#include "supervisor/port.h"
#include <string.h>
#include "py/gc.h"
#include "supervisor/shared/display.h"
enum {
CIRCUITPY_SUPERVISOR_IMMOVABLE_ALLOC_COUNT =
0
// stack + heap
+ 2
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#if INTERNAL_FLASH_FILESYSTEM == 0
+ 1
#endif
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#if CIRCUITPY_USB
+ 1 // device_descriptor_allocation
+ 1 // configuration_descriptor_allocation
+ 1 // string_descriptors_allocation
#endif
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#if CIRCUITPY_USB_HID
+ 1 // hid_report_descriptor_allocation
+ 1 // hid_devices_allocation
#endif
#if CIRCUITPY_USB_VENDOR
+ 1 // usb_vendor_add_descriptor
#endif
,
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CIRCUITPY_SUPERVISOR_MOVABLE_ALLOC_COUNT =
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0
// next_code_allocation
+ 1
// prev_traceback_allocation
+ 1
#if CIRCUITPY_DISPLAYIO
#if CIRCUITPY_TERMINALIO
+ 1
#endif
+ CIRCUITPY_DISPLAY_LIMIT * (
// Maximum needs of one display: max(4 if RGBMATRIX, 1 if SHARPDISPLAY, 0)
#if CIRCUITPY_RGBMATRIX
4
#elif CIRCUITPY_SHARPDISPLAY
1
#else
0
#endif
)
#endif
,
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CIRCUITPY_SUPERVISOR_ALLOC_COUNT = CIRCUITPY_SUPERVISOR_IMMOVABLE_ALLOC_COUNT + CIRCUITPY_SUPERVISOR_MOVABLE_ALLOC_COUNT
};
// The lowest two bits of a valid length are always zero, so we can use them to mark an allocation
// as a hole (freed by the client but not yet reclaimed into the free middle) and as movable.
#define FLAGS 3
#define HOLE 1
#define MOVABLE 2
static supervisor_allocation allocations[CIRCUITPY_SUPERVISOR_ALLOC_COUNT];
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supervisor_allocation *old_allocations;
typedef struct _supervisor_allocation_node {
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struct _supervisor_allocation_node *next;
size_t length;
// We use uint32_t to ensure word (4 byte) alignment.
uint32_t data[];
} supervisor_allocation_node;
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supervisor_allocation_node *low_head;
supervisor_allocation_node *high_head;
// Intermediate (void*) is to suppress -Wcast-align warning. Alignment will always be correct
// because this only reverses how (alloc)->ptr was obtained as &(node->data[0]).
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#define ALLOCATION_NODE(alloc) ((supervisor_allocation_node *)(void *)((char *)((alloc)->ptr) - sizeof(supervisor_allocation_node)))
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void free_memory(supervisor_allocation *allocation) {
if (allocation == NULL || allocation->ptr == NULL) {
return;
}
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supervisor_allocation_node *node = ALLOCATION_NODE(allocation);
if (node == low_head) {
do {
low_head = low_head->next;
} while (low_head != NULL && (low_head->length & HOLE));
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} else if (node == high_head) {
do {
high_head = high_head->next;
} while (high_head != NULL && (high_head->length & HOLE));
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} else {
// Check if it's in the list of embedded allocations.
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supervisor_allocation_node **emb = &MP_STATE_VM(first_embedded_allocation);
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while (*emb != NULL && *emb != node) {
emb = &((*emb)->next);
}
if (*emb != NULL) {
// Found, remove it from the list.
*emb = node->next;
m_free(node
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#if MICROPY_MALLOC_USES_ALLOCATED_SIZE
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, sizeof(supervisor_allocation_node) + (node->length & ~FLAGS)
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#endif
);
} else {
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// Else it must be within the low or high ranges and becomes a hole.
node->length = ((node->length & ~FLAGS) | HOLE);
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}
}
allocation->ptr = NULL;
}
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supervisor_allocation *allocation_from_ptr(void *ptr) {
// When called from the context of supervisor_move_memory() (old_allocations != NULL), search
// by old pointer to give clients a way of mapping from old to new pointer. But not if
// ptr == NULL, then the caller wants an allocation whose current ptr is NULL.
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supervisor_allocation *list = (old_allocations && ptr) ? old_allocations : &allocations[0];
for (size_t index = 0; index < CIRCUITPY_SUPERVISOR_ALLOC_COUNT; index++) {
if (list[index].ptr == ptr) {
return &allocations[index];
}
}
return NULL;
}
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supervisor_allocation *allocate_remaining_memory(void) {
return allocate_memory((uint32_t)-1, false, false);
}
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static supervisor_allocation_node *find_hole(supervisor_allocation_node *node, size_t length) {
for (; node != NULL; node = node->next) {
if (node->length == (length | HOLE)) {
break;
}
}
return node;
}
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static supervisor_allocation_node *allocate_memory_node(uint32_t length, bool high, bool movable) {
if (CIRCUITPY_SUPERVISOR_MOVABLE_ALLOC_COUNT == 0) {
assert(!movable);
}
// supervisor_move_memory() currently does not support movable allocations on the high side, it
// must be extended first if this is ever needed.
assert(!(high && movable));
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uint32_t *low_address = low_head ? low_head->data + low_head->length / 4 : port_heap_get_bottom();
uint32_t *high_address = high_head ? (uint32_t *)high_head : port_heap_get_top();
// Special case for allocate_remaining_memory(), avoids computing low/high_address twice.
if (length == (uint32_t)-1) {
length = (high_address - low_address) * 4 - sizeof(supervisor_allocation_node);
}
if (length == 0 || length % 4 != 0) {
return NULL;
}
// 1. Matching hole on the requested side?
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supervisor_allocation_node *node = find_hole(high ? high_head : low_head, length);
if (!node) {
// 2. Enough free space in the middle?
if ((high_address - low_address) * 4 >= (int32_t)(sizeof(supervisor_allocation_node) + length)) {
if (high) {
high_address -= (sizeof(supervisor_allocation_node) + length) / 4;
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node = (supervisor_allocation_node *)high_address;
node->next = high_head;
high_head = node;
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} else {
node = (supervisor_allocation_node *)low_address;
node->next = low_head;
low_head = node;
}
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} else {
// 3. Matching hole on the other side?
node = find_hole(high ? low_head : high_head, length);
if (!node) {
// 4. GC allocation?
if (movable && gc_alloc_possible()) {
node = m_malloc_maybe(sizeof(supervisor_allocation_node) + length, true);
if (node) {
node->next = MP_STATE_VM(first_embedded_allocation);
MP_STATE_VM(first_embedded_allocation) = node;
}
}
if (!node) {
// 5. Give up.
return NULL;
}
}
}
}
node->length = length;
if (movable) {
node->length |= MOVABLE;
}
return node;
}
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supervisor_allocation *allocate_memory(uint32_t length, bool high, bool movable) {
supervisor_allocation_node *node = allocate_memory_node(length, high, movable);
if (!node) {
return NULL;
}
// Find the first free allocation.
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supervisor_allocation *alloc = allocation_from_ptr(NULL);
if (!alloc) {
// We should free node again to avoid leaking, but something is wrong anyway if clients try
// to make more allocations than available, so don't bother.
return NULL;
}
alloc->ptr = &(node->data[0]);
return alloc;
}
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size_t get_allocation_length(supervisor_allocation *allocation) {
return ALLOCATION_NODE(allocation)->length & ~FLAGS;
}
void supervisor_move_memory(void) {
// This whole function is not needed when there are no movable allocations, let it be optimized
// out.
if (CIRCUITPY_SUPERVISOR_MOVABLE_ALLOC_COUNT == 0) {
return;
}
// This must be called exactly after freeing the heap, so that the embedded allocations, if any,
// are now in the free region.
assert(MP_STATE_VM(first_embedded_allocation) == NULL || (
(low_head == NULL || low_head < MP_STATE_VM(first_embedded_allocation)) &&
(high_head == NULL || MP_STATE_VM(first_embedded_allocation) < high_head)));
// Save the old pointers for allocation_from_ptr().
supervisor_allocation old_allocations_array[CIRCUITPY_SUPERVISOR_ALLOC_COUNT];
memcpy(old_allocations_array, allocations, sizeof(allocations));
// Compact the low side. Traverse the list repeatedly, finding movable allocations preceded by a
// hole and swapping them, until no more are found. This is not the most runtime-efficient way,
// but probably the shortest and simplest code.
bool acted;
do {
acted = false;
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supervisor_allocation_node **nodep = &low_head;
while (*nodep != NULL && (*nodep)->next != NULL) {
if (((*nodep)->length & MOVABLE) && ((*nodep)->next->length & HOLE)) {
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supervisor_allocation_node *oldnode = *nodep;
supervisor_allocation_node *start = oldnode->next;
supervisor_allocation *alloc = allocation_from_ptr(&(oldnode->data[0]));
assert(alloc != NULL);
alloc->ptr = &(start->data[0]);
oldnode->next = start->next;
size_t holelength = start->length;
size_t size = sizeof(supervisor_allocation_node) + (oldnode->length & ~FLAGS);
memmove(start, oldnode, size);
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supervisor_allocation_node *newhole = (supervisor_allocation_node *)(void *)((char *)start + size);
newhole->next = start;
newhole->length = holelength;
*nodep = newhole;
acted = true;
}
nodep = &((*nodep)->next);
}
} while (acted);
// Any holes bubbled to the top can be absorbed into the free middle.
while (low_head != NULL && (low_head->length & HOLE)) {
low_head = low_head->next;
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}
;
// Don't bother compacting the high side, there are no movable allocations and no holes there in
// current usage.
// Promote the embedded allocations to top-level ones, compacting them at the beginning of the
// now free region (or possibly in matching holes).
// The linked list is unordered, but allocations must be processed in order to avoid risking
// overwriting each other. To that end, repeatedly find the lowest element of the list, remove
// it from the list, and process it. This ad-hoc selection sort results in substantially shorter
// code than using the qsort() function from the C library.
while (MP_STATE_VM(first_embedded_allocation)) {
// First element is first candidate.
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supervisor_allocation_node **pminnode = &MP_STATE_VM(first_embedded_allocation);
// Iterate from second element (if any) on.
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for (supervisor_allocation_node **pnode = &(MP_STATE_VM(first_embedded_allocation)->next); *pnode != NULL; pnode = &(*pnode)->next) {
if (*pnode < *pminnode) {
pminnode = pnode;
}
}
// Remove from list.
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supervisor_allocation_node *node = *pminnode;
*pminnode = node->next;
// Process.
size_t length = (node->length & ~FLAGS);
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supervisor_allocation *alloc = allocation_from_ptr(&(node->data[0]));
assert(alloc != NULL);
// This may overwrite the header of node if it happened to be there already, but not the
// data.
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supervisor_allocation_node *new_node = allocate_memory_node(length, false, true);
// There must be enough free space.
assert(new_node != NULL);
memmove(&(new_node->data[0]), &(node->data[0]), length);
alloc->ptr = &(new_node->data[0]);
}
// Notify clients that their movable allocations may have moved.
old_allocations = &old_allocations_array[0];
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#if CIRCUITPY_DISPLAYIO
supervisor_display_move_memory();
#endif
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// Add calls to further clients here.
old_allocations = NULL;
}