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umm_malloc.cpp
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/* ----------------------------------------------------------------------------
* umm_malloc.c - a memory allocator for embedded systems (microcontrollers)
*
* See copyright notice in LICENSE.TXT
* ----------------------------------------------------------------------------
*
* R.Hempel 2007-09-22 - Original
* R.Hempel 2008-12-11 - Added MIT License biolerplate
* - realloc() now looks to see if previous block is free
* - made common operations functions
* R.Hempel 2009-03-02 - Added macros to disable tasking
* - Added function to dump heap and check for valid free
* pointer
* R.Hempel 2009-03-09 - Changed name to umm_malloc to avoid conflicts with
* the mm_malloc() library functions
* - Added some test code to assimilate a free block
* with the very block if possible. Complicated and
* not worth the grief.
* D.Frank 2014-04-02 - Fixed heap configuration when UMM_TEST_MAIN is NOT set,
* added user-dependent configuration file umm_malloc_cfg.h
* ----------------------------------------------------------------------------
*
* Note: when upgrading this file with upstream code, replace all %i with %d in
* printf format strings. ets_printf doesn't handle %i.
*
* ----------------------------------------------------------------------------
*
* This is a memory management library specifically designed to work with the
* ARM7 embedded processor, but it should work on many other 32 bit processors,
* as well as 16 and 8 bit devices.
*
* ACKNOWLEDGEMENTS
*
* Joerg Wunsch and the avr-libc provided the first malloc() implementation
* that I examined in detail.
*
* http: *www.nongnu.org/avr-libc
*
* Doug Lea's paper on malloc() was another excellent reference and provides
* a lot of detail on advanced memory management techniques such as binning.
*
* http: *g.oswego.edu/dl/html/malloc.html
*
* Bill Dittman provided excellent suggestions, including macros to support
* using these functions in critical sections, and for optimizing realloc()
* further by checking to see if the previous block was free and could be
* used for the new block size. This can help to reduce heap fragmentation
* significantly.
*
* Yaniv Ankin suggested that a way to dump the current heap condition
* might be useful. I combined this with an idea from plarroy to also
* allow checking a free pointer to make sure it's valid.
*
* ----------------------------------------------------------------------------
*
* The memory manager assumes the following things:
*
* 1. The standard POSIX compliant malloc/realloc/free semantics are used
* 2. All memory used by the manager is allocated at link time, it is aligned
* on a 32 bit boundary, it is contiguous, and its extent (start and end
* address) is filled in by the linker.
* 3. All memory used by the manager is initialized to 0 as part of the
* runtime startup routine. No other initialization is required.
*
* The fastest linked list implementations use doubly linked lists so that
* its possible to insert and delete blocks in constant time. This memory
* manager keeps track of both free and used blocks in a doubly linked list.
*
* Most memory managers use some kind of list structure made up of pointers
* to keep track of used - and sometimes free - blocks of memory. In an
* embedded system, this can get pretty expensive as each pointer can use
* up to 32 bits.
*
* In most embedded systems there is no need for managing large blocks
* of memory dynamically, so a full 32 bit pointer based data structure
* for the free and used block lists is wasteful. A block of memory on
* the free list would use 16 bytes just for the pointers!
*
* This memory management library sees the malloc heap as an array of blocks,
* and uses block numbers to keep track of locations. The block numbers are
* 15 bits - which allows for up to 32767 blocks of memory. The high order
* bit marks a block as being either free or in use, which will be explained
* later.
*
* The result is that a block of memory on the free list uses just 8 bytes
* instead of 16.
*
* In fact, we go even one step futher when we realize that the free block
* index values are available to store data when the block is allocated.
*
* The overhead of an allocated block is therefore just 4 bytes.
*
* Each memory block holds 8 bytes, and there are up to 32767 blocks
* available, for about 256K of heap space. If that's not enough, you
* can always add more data bytes to the body of the memory block
* at the expense of free block size overhead.
*
* There are a lot of little features and optimizations in this memory
* management system that makes it especially suited to small embedded, but
* the best way to appreciate them is to review the data structures and
* algorithms used, so let's get started.
*
* ----------------------------------------------------------------------------
*
* We have a general notation for a block that we'll use to describe the
* different scenarios that our memory allocation algorithm must deal with:
*
* +----+----+----+----+
* c |* n | p | nf | pf |
* +----+----+----+----+
*
* Where - c is the index of this block
* * is the indicator for a free block
* n is the index of the next block in the heap
* p is the index of the previous block in the heap
* nf is the index of the next block in the free list
* pf is the index of the previous block in the free list
*
* The fact that we have forward and backward links in the block descriptors
* means that malloc() and free() operations can be very fast. It's easy
* to either allocate the whole free item to a new block or to allocate part
* of the free item and leave the rest on the free list without traversing
* the list from front to back first.
*
* The entire block of memory used by the heap is assumed to be initialized
* to 0. The very first block in the heap is special - it't the head of the
* free block list. It is never assimilated with a free block (more on this
* later).
*
* Once a block has been allocated to the application, it looks like this:
*
* +----+----+----+----+
* c | n | p | ... |
* +----+----+----+----+
*
* Where - c is the index of this block
* n is the index of the next block in the heap
* p is the index of the previous block in the heap
*
* Note that the free list information is gone, because it's now being used to
* store actual data for the application. It would have been nice to store
* the next and previous free list indexes as well, but that would be a waste
* of space. If we had even 500 items in use, that would be 2,000 bytes for
* free list information. We simply can't afford to waste that much.
*
* The address of the ... area is what is returned to the application
* for data storage.
*
* The following sections describe the scenarios encountered during the
* operation of the library. There are two additional notation conventions:
*
* ?? inside a pointer block means that the data is irrelevant. We don't care
* about it because we don't read or modify it in the scenario being
* described.
*
* ... between memory blocks indicates zero or more additional blocks are
* allocated for use by the upper block.
*
* And while we're talking about "upper" and "lower" blocks, we should make
* a comment about adresses. In the diagrams, a block higher up in the
* picture is at a lower address. And the blocks grow downwards their
* block index increases as does their physical address.
*
* Finally, there's one very important characteristic of the individual
* blocks that make up the heap - there can never be two consecutive free
* memory blocks, but there can be consecutive used memory blocks.
*
* The reason is that we always want to have a short free list of the
* largest possible block sizes. By always assimilating a newly freed block
* with adjacent free blocks, we maximize the size of each free memory area.
*
*---------------------------------------------------------------------------
*
* Operation of malloc right after system startup
*
* As part of the system startup code, all of the heap has been cleared.
*
* During the very first malloc operation, we start traversing the free list
* starting at index 0. The index of the next free block is 0, which means
* we're at the end of the list!
*
* At this point, the malloc has a special test that checks if the current
* block index is 0, which it is. This special case initializes the free
* list to point at block index 1.
*
* BEFORE AFTER
*
* +----+----+----+----+ +----+----+----+----+
* 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 |
* +----+----+----+----+ +----+----+----+----+
* +----+----+----+----+
* 1 | 0 | 0 | 0 | 0 |
* +----+----+----+----+
*
* The heap is now ready to complete the first malloc operation.
*
* ----------------------------------------------------------------------------
*
* Operation of malloc when we have reached the end of the free list and
* there is no block large enough to accommodate the request.
*
* This happens at the very first malloc operation, or any time the free
* list is traversed and no free block large enough for the request is
* found.
*
* The current block pointer will be at the end of the free list, and we
* know we're at the end of the list because the nf index is 0, like this:
*
* BEFORE AFTER
*
* +----+----+----+----+ +----+----+----+----+
* pf |*?? | ?? | cf | ?? | pf |*?? | ?? | lf | ?? |
* +----+----+----+----+ +----+----+----+----+
* ... ...
* +----+----+----+----+ +----+----+----+----+
* p | cf | ?? | ... | p | cf | ?? | ... |
* +----+----+----+----+ +----+----+----+----+
* +----+----+----+----+ +----+----+----+----+
* cf | 0 | p | 0 | pf | c | lf | p | ... |
* +----+----+----+----+ +----+----+----+----+
* +----+----+----+----+
* lf | 0 | cf | 0 | pf |
* +----+----+----+----+
*
* As we walk the free list looking for a block of size b or larger, we get
* to cf, which is the last item in the free list. We know this because the
* next index is 0.
*
* So we're going to turn cf into the new block of memory, and then create
* a new block that represents the last free entry (lf) and adjust the prev
* index of lf to point at the block we just created. We also need to adjust
* the next index of the new block (c) to point to the last free block.
*
* Note that the next free index of the pf block must point to the new lf
* because cf is no longer a free block!
*
* ----------------------------------------------------------------------------
*
* Operation of malloc when we have found a block (cf) that will fit the
* current request of b units exactly.
*
* This one is pretty easy, just clear the free list bit in the current
* block and unhook it from the free list.
*
* BEFORE AFTER
*
* +----+----+----+----+ +----+----+----+----+
* pf |*?? | ?? | cf | ?? | pf |*?? | ?? | nf | ?? |
* +----+----+----+----+ +----+----+----+----+
* ... ...
* +----+----+----+----+ +----+----+----+----+
* p | cf | ?? | ... | p | cf | ?? | ... |
* +----+----+----+----+ +----+----+----+----+
* +----+----+----+----+ +----+----+----+----+ Clear the free
* cf |* n | p | nf | pf | cf | n | p | .. | list bit here
* +----+----+----+----+ +----+----+----+----+
* +----+----+----+----+ +----+----+----+----+
* n | ?? | cf | ... | n | ?? | cf | ... |
* +----+----+----+----+ +----+----+----+----+
* ... ...
* +----+----+----+----+ +----+----+----+----+
* nf |*?? | ?? | ?? | cf | nf | ?? | ?? | ?? | pf |
* +----+----+----+----+ +----+----+----+----+
*
* Unhooking from the free list is accomplished by adjusting the next and
* prev free list index values in the pf and nf blocks.
*
* ----------------------------------------------------------------------------
*
* Operation of malloc when we have found a block that will fit the current
* request of b units with some left over.
*
* We'll allocate the new block at the END of the current free block so we
* don't have to change ANY free list pointers.
*
* BEFORE AFTER
*
* +----+----+----+----+ +----+----+----+----+
* pf |*?? | ?? | cf | ?? | pf |*?? | ?? | cf | ?? |
* +----+----+----+----+ +----+----+----+----+
* ... ...
* +----+----+----+----+ +----+----+----+----+
* p | cf | ?? | ... | p | cf | ?? | ... |
* +----+----+----+----+ +----+----+----+----+
* +----+----+----+----+ +----+----+----+----+
* cf |* n | p | nf | pf | cf |* c | p | nf | pf |
* +----+----+----+----+ +----+----+----+----+
* +----+----+----+----+ This is the new
* c | n | cf | .. | block at cf+b
* +----+----+----+----+
* +----+----+----+----+ +----+----+----+----+
* n | ?? | cf | ... | n | ?? | c | ... |
* +----+----+----+----+ +----+----+----+----+
* ... ...
* +----+----+----+----+ +----+----+----+----+
* nf |*?? | ?? | ?? | cf | nf | ?? | ?? | ?? | pf |
* +----+----+----+----+ +----+----+----+----+
*
* This one is prety easy too, except we don't need to mess with the
* free list indexes at all becasue we'll allocate the new block at the
* end of the current free block. We do, however have to adjust the
* indexes in cf, c, and n.
*
* ----------------------------------------------------------------------------
*
* That covers the initialization and all possible malloc scenarios, so now
* we need to cover the free operation possibilities...
*
* The operation of free depends on the position of the current block being
* freed relative to free list items immediately above or below it. The code
* works like this:
*
* if next block is free
* assimilate with next block already on free list
* if prev block is free
* assimilate with prev block already on free list
* else
* put current block at head of free list
*
* ----------------------------------------------------------------------------
*
* Step 1 of the free operation checks if the next block is free, and if it
* is then insert this block into the free list and assimilate the next block
* with this one.
*
* Note that c is the block we are freeing up, cf is the free block that
* follows it.
*
* BEFORE AFTER
*
* +----+----+----+----+ +----+----+----+----+
* pf |*?? | ?? | cf | ?? | pf |*?? | ?? | nf | ?? |
* +----+----+----+----+ +----+----+----+----+
* ... ...
* +----+----+----+----+ +----+----+----+----+
* p | c | ?? | ... | p | c | ?? | ... |
* +----+----+----+----+ +----+----+----+----+
* +----+----+----+----+ +----+----+----+----+ This block is
* c | cf | p | ... | c | nn | p | ... | disconnected
* +----+----+----+----+ +----+----+----+----+ from free list,
* +----+----+----+----+ assimilated with
* cf |*nn | c | nf | pf | the next, and
* +----+----+----+----+ ready for step 2
* +----+----+----+----+ +----+----+----+----+
* nn | ?? | cf | ?? | ?? | nn | ?? | c | ... |
* +----+----+----+----+ +----+----+----+----+
* ... ...
* +----+----+----+----+ +----+----+----+----+
* nf |*?? | ?? | ?? | cf | nf |*?? | ?? | ?? | pf |
* +----+----+----+----+ +----+----+----+----+
*
* Take special note that the newly assimilated block (c) is completely
* disconnected from the free list, and it does not have its free list
* bit set. This is important as we move on to step 2 of the procedure...
*
* ----------------------------------------------------------------------------
*
* Step 2 of the free operation checks if the prev block is free, and if it
* is then assimilate it with this block.
*
* Note that c is the block we are freeing up, pf is the free block that
* precedes it.
*
* BEFORE AFTER
*
* +----+----+----+----+ +----+----+----+----+ This block has
* pf |* c | ?? | nf | ?? | pf |* n | ?? | nf | ?? | assimilated the
* +----+----+----+----+ +----+----+----+----+ current block
* +----+----+----+----+
* c | n | pf | ... |
* +----+----+----+----+
* +----+----+----+----+ +----+----+----+----+
* n | ?? | c | ... | n | ?? | pf | ?? | ?? |
* +----+----+----+----+ +----+----+----+----+
* ... ...
* +----+----+----+----+ +----+----+----+----+
* nf |*?? | ?? | ?? | pf | nf |*?? | ?? | ?? | pf |
* +----+----+----+----+ +----+----+----+----+
*
* Nothing magic here, except that when we're done, the current block (c)
* is gone since it's been absorbed into the previous free block. Note that
* the previous step guarantees that the next block (n) is not free.
*
* ----------------------------------------------------------------------------
*
* Step 3 of the free operation only runs if the previous block is not free.
* it just inserts the current block to the head of the free list.
*
* Remember, 0 is always the first block in the memory heap, and it's always
* head of the free list!
*
* BEFORE AFTER
*
* +----+----+----+----+ +----+----+----+----+
* 0 | ?? | ?? | nf | 0 | 0 | ?? | ?? | c | 0 |
* +----+----+----+----+ +----+----+----+----+
* ... ...
* +----+----+----+----+ +----+----+----+----+
* p | c | ?? | ... | p | c | ?? | ... |
* +----+----+----+----+ +----+----+----+----+
* +----+----+----+----+ +----+----+----+----+
* c | n | p | .. | c |* n | p | nf | 0 |
* +----+----+----+----+ +----+----+----+----+
* +----+----+----+----+ +----+----+----+----+
* n | ?? | c | ... | n | ?? | c | ... |
* +----+----+----+----+ +----+----+----+----+
* ... ...
* +----+----+----+----+ +----+----+----+----+
* nf |*?? | ?? | ?? | 0 | nf |*?? | ?? | ?? | c |
* +----+----+----+----+ +----+----+----+----+
*
* Again, nothing spectacular here, we're simply adjusting a few pointers
* to make the most recently freed block the first item in the free list.
*
* That's because finding the previous free block would mean a reverse
* traversal of blocks until we found a free one, and it's just easier to
* put it at the head of the list. No traversal is needed.
*
* ----------------------------------------------------------------------------
*
* Finally, we can cover realloc, which has the following basic operation.
*
* The first thing we do is assimilate up with the next free block of
* memory if possible. This step might help if we're resizing to a bigger
* block of memory. It also helps if we're downsizing and creating a new
* free block with the leftover memory.
*
* First we check to see if the next block is free, and we assimilate it
* to this block if it is. If the previous block is also free, and if
* combining it with the current block would satisfy the request, then we
* assimilate with that block and move the current data down to the new
* location.
*
* Assimilating with the previous free block and moving the data works
* like this:
*
* BEFORE AFTER
*
* +----+----+----+----+ +----+----+----+----+
* pf |*?? | ?? | cf | ?? | pf |*?? | ?? | nf | ?? |
* +----+----+----+----+ +----+----+----+----+
* ... ...
* +----+----+----+----+ +----+----+----+----+
* cf |* c | ?? | nf | pf | c | n | ?? | ... | The data gets
* +----+----+----+----+ +----+----+----+----+ moved from c to
* +----+----+----+----+ the new data area
* c | n | cf | ... | in cf, then c is
* +----+----+----+----+ adjusted to cf
* +----+----+----+----+ +----+----+----+----+
* n | ?? | c | ... | n | ?? | c | ?? | ?? |
* +----+----+----+----+ +----+----+----+----+
* ... ...
* +----+----+----+----+ +----+----+----+----+
* nf |*?? | ?? | ?? | cf | nf |*?? | ?? | ?? | pf |
* +----+----+----+----+ +----+----+----+----+
*
*
* Once we're done that, there are three scenarios to consider:
*
* 1. The current block size is exactly the right size, so no more work is
* needed.
*
* 2. The current block is bigger than the new required size, so carve off
* the excess and add it to the free list.
*
* 3. The current block is still smaller than the required size, so malloc
* a new block of the correct size and copy the current data into the new
* block before freeing the current block.
*
* The only one of these scenarios that involves an operation that has not
* yet been described is the second one, and it's shown below:
*
* BEFORE AFTER
*
* +----+----+----+----+ +----+----+----+----+
* p | c | ?? | ... | p | c | ?? | ... |
* +----+----+----+----+ +----+----+----+----+
* +----+----+----+----+ +----+----+----+----+
* c | n | p | ... | c | s | p | ... |
* +----+----+----+----+ +----+----+----+----+
* +----+----+----+----+ This is the
* s | n | c | .. | new block at
* +----+----+----+----+ c+blocks
* +----+----+----+----+ +----+----+----+----+
* n | ?? | c | ... | n | ?? | s | ... |
* +----+----+----+----+ +----+----+----+----+
*
* Then we call free() with the adress of the data portion of the new
* block (s) which adds it to the free list.
*
* ----------------------------------------------------------------------------
*/
#include <stdio.h>
#include <string.h>
#include <pgmspace.h>
#include "umm_malloc.h"
#include "umm_malloc_cfg.h" /* user-dependent */
extern "C" {
// From UMM, the last caller of a malloc/realloc/calloc which failed:
extern void *umm_last_fail_alloc_addr;
extern int umm_last_fail_alloc_size;
#ifndef UMM_FIRST_FIT
# ifndef UMM_BEST_FIT
# define UMM_BEST_FIT
# endif
#endif
#ifndef DBG_LOG_LEVEL
# undef DBG_LOG_LEVEL
# define DBG_LOG_LEVEL 0
#else
# undef DBG_LOG_LEVEL
# define DBG_LOG_LEVEL DBG_LOG_LEVEL
#endif
// Macro to place constant strings into PROGMEM and print them properly
#define printf(fmt, ...) printf(PSTR(fmt), ## __VA_ARGS__ )
/* -- dbglog {{{ */
/* ----------------------------------------------------------------------------
* A set of macros that cleans up code that needs to produce debug
* or log information.
*
* See copyright notice in LICENSE.TXT
* ----------------------------------------------------------------------------
*
* There are macros to handle the following decreasing levels of detail:
*
* 6 = TRACE
* 5 = DEBUG
* 4 = CRITICAL
* 3 = ERROR
* 2 = WARNING
* 1 = INFO
* 0 = FORCE - The printf is always compiled in and is called only when
* the first parameter to the macro is non-0
*
* ----------------------------------------------------------------------------
*
* The following #define should be set up before this file is included so
* that we can be sure that the correct macros are defined.
*
* #define DBG_LOG_LEVEL x
* ----------------------------------------------------------------------------
*/
#undef DBG_LOG_TRACE
#undef DBG_LOG_DEBUG
#undef DBG_LOG_CRITICAL
#undef DBG_LOG_ERROR
#undef DBG_LOG_WARNING
#undef DBG_LOG_INFO
#undef DBG_LOG_FORCE
/* ------------------------------------------------------------------------- */
#if DBG_LOG_LEVEL >= 6
# define DBG_LOG_TRACE( format, ... ) printf( format, ## __VA_ARGS__ )
#else
# define DBG_LOG_TRACE( format, ... )
#endif
#if DBG_LOG_LEVEL >= 5
# define DBG_LOG_DEBUG( format, ... ) printf( format, ## __VA_ARGS__ )
#else
# define DBG_LOG_DEBUG( format, ... )
#endif
#if DBG_LOG_LEVEL >= 4
# define DBG_LOG_CRITICAL( format, ... ) printf( format, ## __VA_ARGS__ )
#else
# define DBG_LOG_CRITICAL( format, ... )
#endif
#if DBG_LOG_LEVEL >= 3
# define DBG_LOG_ERROR( format, ... ) printf( format, ## __VA_ARGS__ )
#else
# define DBG_LOG_ERROR( format, ... )
#endif
#if DBG_LOG_LEVEL >= 2
# define DBG_LOG_WARNING( format, ... ) printf( format, ## __VA_ARGS__ )
#else
# define DBG_LOG_WARNING( format, ... )
#endif
#if DBG_LOG_LEVEL >= 1
# define DBG_LOG_INFO( format, ... ) printf( format, ## __VA_ARGS__ )
#else
# define DBG_LOG_INFO( format, ... )
#endif
#define DBG_LOG_FORCE( force, format, ... ) {if(force) {printf( format, ## __VA_ARGS__ );}}
/* }}} */
/* ------------------------------------------------------------------------- */
UMM_H_ATTPACKPRE typedef struct umm_ptr_t {
unsigned short int next;
unsigned short int prev;
} UMM_H_ATTPACKSUF umm_ptr;
UMM_H_ATTPACKPRE typedef struct umm_block_t {
union {
umm_ptr used;
} header;
union {
umm_ptr free;
unsigned char data[4];
} body;
} UMM_H_ATTPACKSUF umm_block;
#define UMM_FREELIST_MASK (0x8000)
#define UMM_BLOCKNO_MASK (0x7FFF)
/* ------------------------------------------------------------------------- */
#ifdef UMM_REDEFINE_MEM_FUNCTIONS
# define umm_free free
# define umm_malloc malloc
# define umm_calloc calloc
# define umm_realloc realloc
#endif
umm_block *umm_heap = NULL;
unsigned short int umm_numblocks = 0;
#define UMM_NUMBLOCKS (umm_numblocks)
/* ------------------------------------------------------------------------ */
#define UMM_BLOCK(b) (umm_heap[b])
#define UMM_NBLOCK(b) (UMM_BLOCK(b).header.used.next)
#define UMM_PBLOCK(b) (UMM_BLOCK(b).header.used.prev)
#define UMM_NFREE(b) (UMM_BLOCK(b).body.free.next)
#define UMM_PFREE(b) (UMM_BLOCK(b).body.free.prev)
#define UMM_DATA(b) (UMM_BLOCK(b).body.data)
/* integrity check (UMM_INTEGRITY_CHECK) {{{ */
#if defined(UMM_INTEGRITY_CHECK)
/*
* Perform integrity check of the whole heap data. Returns 1 in case of
* success, 0 otherwise.
*
* First of all, iterate through all free blocks, and check that all backlinks
* match (i.e. if block X has next free block Y, then the block Y should have
* previous free block set to X).
*
* Additionally, we check that each free block is correctly marked with
* `UMM_FREELIST_MASK` on the `next` pointer: during iteration through free
* list, we mark each free block by the same flag `UMM_FREELIST_MASK`, but
* on `prev` pointer. We'll check and unmark it later.
*
* Then, we iterate through all blocks in the heap, and similarly check that
* all backlinks match (i.e. if block X has next block Y, then the block Y
* should have previous block set to X).
*
* But before checking each backlink, we check that the `next` and `prev`
* pointers are both marked with `UMM_FREELIST_MASK`, or both unmarked.
* This way, we ensure that the free flag is in sync with the free pointers
* chain.
*/
static int integrity_check(void) {
int ok = 1;
unsigned short int prev;
unsigned short int cur;
if (umm_heap == NULL) {
umm_init();
}
/* Iterate through all free blocks */
prev = 0;
while(1) {
cur = UMM_NFREE(prev);
/* Check that next free block number is valid */
if (cur >= UMM_NUMBLOCKS) {
printf("heap integrity broken: too large next free num: %d "
"(in block %d, addr 0x%lx)\n", cur, prev,
(unsigned long)&UMM_NBLOCK(prev));
ok = 0;
goto clean;
}
if (cur == 0) {
/* No more free blocks */
break;
}
/* Check if prev free block number matches */
if (UMM_PFREE(cur) != prev) {
printf("heap integrity broken: free links don't match: "
"%d -> %d, but %d -> %d\n",
prev, cur, cur, UMM_PFREE(cur));
ok = 0;
goto clean;
}
UMM_PBLOCK(cur) |= UMM_FREELIST_MASK;
prev = cur;
}
/* Iterate through all blocks */
prev = 0;
while(1) {
cur = UMM_NBLOCK(prev) & UMM_BLOCKNO_MASK;
/* Check that next block number is valid */
if (cur >= UMM_NUMBLOCKS) {
printf("heap integrity broken: too large next block num: %d "
"(in block %d, addr 0x%lx)\n", cur, prev,
(unsigned long)&UMM_NBLOCK(prev));
ok = 0;
goto clean;
}
if (cur == 0) {
/* No more blocks */
break;
}
/* make sure the free mark is appropriate, and unmark it */
if ((UMM_NBLOCK(cur) & UMM_FREELIST_MASK)
!= (UMM_PBLOCK(cur) & UMM_FREELIST_MASK))
{
printf("heap integrity broken: mask wrong at addr 0x%lx: n=0x%x, p=0x%x\n",
(unsigned long)&UMM_NBLOCK(cur),
(UMM_NBLOCK(cur) & UMM_FREELIST_MASK),
(UMM_PBLOCK(cur) & UMM_FREELIST_MASK)
);
ok = 0;
goto clean;
}
/* unmark */
UMM_PBLOCK(cur) &= UMM_BLOCKNO_MASK;
/* Check if prev block number matches */
if (UMM_PBLOCK(cur) != prev) {
printf("heap integrity broken: block links don't match: "
"%d -> %d, but %d -> %d\n",
prev, cur, cur, UMM_PBLOCK(cur));
ok = 0;
goto clean;
}
prev = cur;
}
clean:
if (!ok){
UMM_HEAP_CORRUPTION_CB();
}
return ok;
}
#define INTEGRITY_CHECK() integrity_check()
#else
/*
* Integrity check is disabled, so just define stub macro
*/
#define INTEGRITY_CHECK() 1
#endif
/* }}} */
/* poisoning (UMM_POISON) {{{ */
#if defined(UMM_POISON)
#define POISON_BYTE (0xa5)
/*
* Yields a size of the poison for the block of size `s`.
* If `s` is 0, returns 0.
*/
#define POISON_SIZE(s) ( \
(s) ? \
(UMM_POISON_SIZE_BEFORE + UMM_POISON_SIZE_AFTER + \
sizeof(UMM_POISONED_BLOCK_LEN_TYPE) \
) : 0 \
)
/*
* Print memory contents starting from given `ptr`
*/
static void dump_mem ( const unsigned char *ptr, size_t len ) {
while (len--) {
printf(" 0x%.2x", (unsigned int)(*ptr++));
}
}
/*
* Put poison data at given `ptr` and `poison_size`
*/
static void put_poison( unsigned char *ptr, size_t poison_size ) {
memset(ptr, POISON_BYTE, poison_size);
}
/*
* Check poison data at given `ptr` and `poison_size`. `where` is a pointer to
* a string, either "before" or "after", meaning, before or after the block.
*
* If poison is there, returns 1.
* Otherwise, prints the appropriate message, and returns 0.
*/
static int check_poison( const unsigned char *ptr, size_t poison_size,
const char *where) {
size_t i;
int ok = 1;
for (i = 0; i < poison_size; i++) {
if (ptr[i] != POISON_BYTE) {
ok = 0;
break;
}
}
if (!ok) {
printf("there is no poison %s the block. "
"Expected poison address: 0x%lx, actual data:",
where, (unsigned long)ptr);
dump_mem(ptr, poison_size);
printf("\n");
}
return ok;
}
/*
* Check if a block is properly poisoned. Must be called only for non-free
* blocks.
*/
static int check_poison_block( umm_block *pblock ) {
int ok = 1;
if (pblock->header.used.next & UMM_FREELIST_MASK) {
printf("check_poison_block is called for free block 0x%lx\n",
(unsigned long)pblock);
} else {
/* the block is used; let's check poison */
unsigned char *pc = (unsigned char *)pblock->body.data;
unsigned char *pc_cur;
pc_cur = pc + sizeof(UMM_POISONED_BLOCK_LEN_TYPE);
if (!check_poison(pc_cur, UMM_POISON_SIZE_BEFORE, "before")) {
printf("block start: %08x\n", pc + sizeof(UMM_POISONED_BLOCK_LEN_TYPE) + UMM_POISON_SIZE_BEFORE);
UMM_HEAP_CORRUPTION_CB();
ok = 0;
goto clean;
}
pc_cur = pc + *((UMM_POISONED_BLOCK_LEN_TYPE *)pc) - UMM_POISON_SIZE_AFTER;
if (!check_poison(pc_cur, UMM_POISON_SIZE_AFTER, "after")) {
printf("block start: %08x\n", pc + sizeof(UMM_POISONED_BLOCK_LEN_TYPE) + UMM_POISON_SIZE_BEFORE);
UMM_HEAP_CORRUPTION_CB();
ok = 0;
goto clean;
}
}
clean:
return ok;
}
/*
* Iterates through all blocks in the heap, and checks poison for all used
* blocks.
*/
static int check_poison_all_blocks(void) {
int ok = 1;
unsigned short int blockNo = 0;
if (umm_heap == NULL) {
umm_init();
}
/* Now iterate through the blocks list */
blockNo = UMM_NBLOCK(blockNo) & UMM_BLOCKNO_MASK;
while( UMM_NBLOCK(blockNo) & UMM_BLOCKNO_MASK ) {
if ( !(UMM_NBLOCK(blockNo) & UMM_FREELIST_MASK) ) {
/* This is a used block (not free), so, check its poison */
ok = check_poison_block(&UMM_BLOCK(blockNo));
if (!ok){
break;
}
}
blockNo = UMM_NBLOCK(blockNo) & UMM_BLOCKNO_MASK;
}
return ok;
}
/*
* Takes a pointer returned by actual allocator function (`_umm_malloc` or
* `_umm_realloc`), puts appropriate poison, and returns adjusted pointer that
* should be returned to the user.
*
* `size_w_poison` is a size of the whole block, including a poison.
*/
static void *get_poisoned( void *vptr, size_t size_w_poison ) {
unsigned char *ptr = (unsigned char *)vptr;
if (size_w_poison != 0 && ptr != NULL) {
/* Put exact length of the user's chunk of memory */
memcpy(ptr, &size_w_poison, sizeof(UMM_POISONED_BLOCK_LEN_TYPE));
/* Poison beginning and the end of the allocated chunk */
put_poison(ptr + sizeof(UMM_POISONED_BLOCK_LEN_TYPE),
UMM_POISON_SIZE_BEFORE);
put_poison(ptr + size_w_poison - UMM_POISON_SIZE_AFTER,
UMM_POISON_SIZE_AFTER);
/* Return pointer at the first non-poisoned byte */
return ptr + sizeof(UMM_POISONED_BLOCK_LEN_TYPE) + UMM_POISON_SIZE_BEFORE;
} else {
return ptr;
}
}
/*
* Takes "poisoned" pointer (i.e. pointer returned from `get_poisoned()`),
* and checks that the poison of this particular block is still there.
*
* Returns unpoisoned pointer, i.e. actual pointer to the allocated memory.
*/
static void *get_unpoisoned( void *vptr ) {
unsigned char *ptr = (unsigned char *)vptr;
if (ptr != NULL) {
unsigned short int c;
ptr -= (sizeof(UMM_POISONED_BLOCK_LEN_TYPE) + UMM_POISON_SIZE_BEFORE);
/* Figure out which block we're in. Note the use of truncated division... */
c = (((char *)ptr)-(char *)(&(umm_heap[0])))/sizeof(umm_block);
check_poison_block(&UMM_BLOCK(c));
}
return ptr;
}
#define CHECK_POISON_ALL_BLOCKS() check_poison_all_blocks()
#define GET_POISONED(ptr, size) get_poisoned(ptr, size)
#define GET_UNPOISONED(ptr) get_unpoisoned(ptr)
#else
/*
* Integrity check is disabled, so just define stub macros
*/
#define POISON_SIZE(s) 0
#define CHECK_POISON_ALL_BLOCKS() 1
#define GET_POISONED(ptr, size) (ptr)
#define GET_UNPOISONED(ptr) (ptr)
#endif
/* }}} */
/* ----------------------------------------------------------------------------
* One of the coolest things about this little library is that it's VERY
* easy to get debug information about the memory heap by simply iterating
* through all of the memory blocks.
*
* As you go through all the blocks, you can check to see if it's a free
* block by looking at the high order bit of the next block index. You can
* also see how big the block is by subtracting the next block index from
* the current block number.
*
* The umm_info function does all of that and makes the results available
* in the ummHeapInfo structure.
* ----------------------------------------------------------------------------
*/
UMM_HEAP_INFO ummHeapInfo;
void ICACHE_FLASH_ATTR *umm_info( void *ptr, int force ) {
unsigned short int blockNo = 0;
if (umm_heap == NULL) {
umm_init();
}
/* Protect the critical section... */
UMM_CRITICAL_ENTRY();
/*
* Clear out all of the entries in the ummHeapInfo structure before doing
* any calculations..
*/
memset( &ummHeapInfo, 0, sizeof( ummHeapInfo ) );