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add support for extra debug padding in every block

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This commit is contained in:
daan 2020-04-06 22:05:10 -07:00
parent b304e24c40
commit 120af372ab
6 changed files with 51 additions and 21 deletions
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24
include/mimalloc-internal.h
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@ -32,6 +32,26 @@ terms of the MIT license. A copy of the license can be found in the file
#define mi_decl_cache_align
#endif
/* -----------------------------------------------------------
Padding
----------------------------------------------------------- */
#if (MI_PADDING)
#define MI_EXTRA_PADDING_XPARAM , size_t __extra_padding
#define MI_EXTRA_PADDING_XARG , __extra_padding
#define MI_EXTRA_PADDING_ARG __extra_padding
static inline size_t mi_extra_padding() {
return MI_PADDING_SIZE + mi_option_get(mi_option_debug_extra_padding);
}
#else
#define MI_EXTRA_PADDING_XPARAM
#define MI_EXTRA_PADDING_XARG
#define MI_EXTRA_PADDING_ARG 0
static inline size_t mi_extra_padding() {
return 0;
}
#endif
// "options.c"
void _mi_fputs(mi_output_fun* out, void* arg, const char* prefix, const char* message);
@ -90,7 +110,7 @@ void _mi_abandoned_await_readers(void);
// "page.c"
void* _mi_malloc_generic(mi_heap_t* heap, size_t size MI_SOURCE_XPARAM) mi_attr_noexcept mi_attr_malloc;
void* _mi_malloc_generic(mi_heap_t* heap, size_t size MI_EXTRA_PADDING_XPARAM MI_SOURCE_XPARAM) mi_attr_noexcept mi_attr_malloc;
void _mi_page_retire(mi_page_t* page); // free the page if there are no other pages with many free blocks
void _mi_page_unfull(mi_page_t* page);
@ -123,7 +143,7 @@ mi_msecs_t _mi_clock_end(mi_msecs_t start);
mi_msecs_t _mi_clock_start(void);
// "alloc.c"
void* _mi_page_malloc(mi_heap_t* heap, mi_page_t* page, size_t size MI_SOURCE_XPARAM) mi_attr_noexcept; // called from `_mi_malloc_generic`
void* _mi_page_malloc(mi_heap_t* heap, mi_page_t* page, size_t size MI_EXTRA_PADDING_XPARAM MI_SOURCE_XPARAM) mi_attr_noexcept; // called from `_mi_malloc_generic`
mi_block_t* _mi_page_ptr_unalign(const mi_segment_t* segment, const mi_page_t* page, const void* p);
bool _mi_free_delayed_block(mi_block_t* block);
void _mi_block_zero_init(const mi_page_t* page, void* p, size_t size);

1
include/mimalloc.h
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@ -338,6 +338,7 @@ typedef enum mi_option_e {
mi_option_eager_commit_delay,
mi_option_reset_delay,
mi_option_use_numa_nodes,
mi_option_debug_extra_padding,
mi_option_os_tag,
mi_option_max_errors,
_mi_option_last,

5
src/alloc-aligned.c
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@ -24,7 +24,8 @@ static mi_decl_restrict void* mi_base_malloc_zero_aligned_at(mi_heap_t* const he
const uintptr_t align_mask = alignment-1; // for any x, `(x & align_mask) == (x % alignment)`
// try if there is a small block available with just the right alignment
const size_t padsize = size + MI_PADDING_SIZE;
const size_t __extra_padding = mi_extra_padding();
const size_t padsize = size + __extra_padding; // safe for overflow as size <= PTRDIFF_MAX
if (mi_likely(padsize <= MI_SMALL_SIZE_MAX)) {
mi_page_t* page = _mi_heap_get_free_small_page(heap,padsize);
const bool is_aligned = (((uintptr_t)page->free+offset) & align_mask)==0;
@ -33,7 +34,7 @@ static mi_decl_restrict void* mi_base_malloc_zero_aligned_at(mi_heap_t* const he
#if MI_STAT>1
mi_heap_stat_increase( heap, malloc, size);
#endif
void* p = _mi_page_malloc(heap,page,padsize MI_SOURCE_XARG); // TODO: inline _mi_page_malloc
void* p = _mi_page_malloc(heap,page,padsize MI_EXTRA_PADDING_XARG MI_SOURCE_XARG); // TODO: inline _mi_page_malloc
mi_assert_internal(p != NULL);
mi_assert_internal(((uintptr_t)p + offset) % alignment == 0);
if (zero) _mi_block_zero_init(page,p,size);

29
src/alloc.c
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@ -19,17 +19,19 @@ terms of the MIT license. A copy of the license can be found in the file
#undef MI_IN_ALLOC_C
// ------------------------------------------------------
// ----------------------------------------------------------------------------------------
// Allocation
// ------------------------------------------------------
// Eventually all allocations pass through `mi_heap_malloc` and `mi_heap_malloc_small`,
// and those end up at `_mi_page_malloc` (sometimes via `_mi_malloc_generic`).
// ----------------------------------------------------------------------------------------
// Fast allocation in a page: just pop from the free list.
// Fall back to generic allocation only if the list is empty.
extern inline void* _mi_page_malloc(mi_heap_t* heap, mi_page_t* page, size_t size MI_SOURCE_XPARAM) mi_attr_noexcept {
extern inline void* _mi_page_malloc(mi_heap_t* heap, mi_page_t* page, size_t size MI_EXTRA_PADDING_XPARAM MI_SOURCE_XPARAM) mi_attr_noexcept {
mi_assert_internal(page->xblock_size==0||mi_page_block_size(page) >= size);
mi_block_t* block = page->free;
if (mi_unlikely(block == NULL)) {
return _mi_malloc_generic(heap, size MI_SOURCE_XARG); // slow path
return _mi_malloc_generic(heap, size MI_EXTRA_PADDING_XARG MI_SOURCE_XARG); // slow path
}
mi_assert_internal(block != NULL && _mi_ptr_page(block) == page);
// pop from the free list
@ -50,13 +52,13 @@ extern inline void* _mi_page_malloc(mi_heap_t* heap, mi_page_t* page, size_t siz
#endif
#if defined(MI_PADDING) && defined(MI_ENCODE_FREELIST)
mi_padding_t* const padding = (mi_padding_t*)((uint8_t*)block + mi_page_usable_block_size(page));
ptrdiff_t delta = ((uint8_t*)padding - (uint8_t*)block - (size - MI_PADDING_SIZE));
mi_assert_internal(delta >= 0 && mi_page_usable_block_size(page) >= (size - MI_PADDING_SIZE + delta));
ptrdiff_t delta = ((uint8_t*)padding - (uint8_t*)block - (size - __extra_padding));
mi_assert_internal(delta >= 0 && mi_page_usable_block_size(page) >= (size - __extra_padding + delta));
padding->canary = (uint32_t)(mi_ptr_encode(page,block,page->keys));
padding->delta = (uint32_t)(delta);
padding->source = __mi_source;
uint8_t* fill = (uint8_t*)padding - delta;
const size_t maxpad = (delta > MI_MAX_ALIGN_SIZE ? MI_MAX_ALIGN_SIZE : delta); // set at most N initial padding bytes
const size_t maxpad = (delta > 4096 ? 4096 : delta); // set at most N initial padding bytes
for (size_t i = 0; i < maxpad; i++) { fill[i] = MI_DEBUG_PADDING; }
#endif
return block;
@ -68,13 +70,17 @@ MI_ALLOC_API1(inline mi_decl_restrict void*, malloc_small, mi_heap_t*, heap, siz
mi_assert(heap!=NULL);
mi_assert(heap->thread_id == 0 || heap->thread_id == _mi_thread_id()); // heaps are thread local
mi_assert(size <= MI_SMALL_SIZE_MAX);
const size_t __extra_padding = mi_extra_padding();
#if (MI_PADDING)
if (size == 0) {
size = sizeof(void*);
}
if ((size + __extra_padding) > MI_SMALL_SIZE_MAX) {
return MI_SOURCE_ARG(mi_heap_malloc, heap, size); // call base malloc in case we were invoked directly
}
#endif
mi_page_t* page = _mi_heap_get_free_small_page(heap,size + MI_PADDING_SIZE);
void* p = _mi_page_malloc(heap, page, size + MI_PADDING_SIZE MI_SOURCE_XARG);
mi_page_t* page = _mi_heap_get_free_small_page(heap,size + __extra_padding);
void* p = _mi_page_malloc(heap, page, size + __extra_padding MI_EXTRA_PADDING_XARG MI_SOURCE_XARG);
mi_assert_internal(p==NULL || mi_usable_size(p) >= size);
#if MI_STAT>1
if (p != NULL) {
@ -89,13 +95,14 @@ MI_ALLOC_API1(inline mi_decl_restrict void*, malloc_small, mi_heap_t*, heap, siz
// The main allocation function
MI_ALLOC_API1(inline mi_decl_restrict void*, malloc, mi_heap_t*, heap, size_t, size)
{
if (mi_likely(size <= MI_SMALL_SIZE_MAX)) {
const size_t __extra_padding = mi_extra_padding();
if (mi_likely(size <= MI_SMALL_SIZE_MAX - __extra_padding && __extra_padding < MI_SMALL_SIZE_MAX)) { // careful for overflow
return mi_base_malloc_small(heap, size MI_SOURCE_XARG);
}
else {
mi_assert(heap!=NULL);
mi_assert(heap->thread_id == 0 || heap->thread_id == _mi_thread_id()); // heaps are thread local
void* const p = _mi_malloc_generic(heap, size + MI_PADDING_SIZE MI_SOURCE_XARG); // note: size can overflow but it is detected in malloc_generic
void* const p = _mi_malloc_generic(heap, size + __extra_padding MI_EXTRA_PADDING_XARG MI_SOURCE_XARG); // note: size + __extra_padding can overflow but it is detected in malloc_generic
mi_assert_internal(p == NULL || mi_usable_size(p) >= size);
#if MI_STAT>1
if (p != NULL) {

1
src/options.c
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@ -77,6 +77,7 @@ static mi_option_desc_t options[_mi_option_last] =
#endif
{ 100, UNINIT, MI_OPTION(reset_delay) }, // reset delay in milli-seconds
{ 0, UNINIT, MI_OPTION(use_numa_nodes) }, // 0 = use available numa nodes, otherwise use at most N nodes.
{ 160, UNINIT, MI_OPTION(debug_extra_padding) }, // extra padding in bytes
{ 100, UNINIT, MI_OPTION(os_tag) }, // only apple specific for now but might serve more or less related purpose
{ 16, UNINIT, MI_OPTION(max_errors) } // maximum errors that are output
};

10
src/page.c
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@ -792,7 +792,7 @@ static mi_page_t* mi_huge_page_alloc(mi_heap_t* heap, size_t size) {
// Generic allocation routine if the fast path (`alloc.c:mi_page_malloc`) does not succeed.
// Note: in debug mode the size includes MI_PADDING_SIZE and might have overflowed.
void* _mi_malloc_generic(mi_heap_t* heap, size_t size MI_SOURCE_XPARAM) mi_attr_noexcept
void* _mi_malloc_generic(mi_heap_t* heap, size_t size MI_EXTRA_PADDING_XPARAM MI_SOURCE_XPARAM) mi_attr_noexcept
{
mi_assert_internal(heap != NULL);
@ -811,8 +811,8 @@ void* _mi_malloc_generic(mi_heap_t* heap, size_t size MI_SOURCE_XPARAM) mi_attr_
// huge allocation?
mi_page_t* page;
const size_t req_size = size - MI_PADDING_SIZE; // correct for padding_size in case of an overflow on `size`
if (mi_unlikely(req_size > (MI_LARGE_OBJ_SIZE_MAX - MI_PADDING_SIZE) )) {
const size_t req_size = size - MI_EXTRA_PADDING_ARG; // correct for padding_size in case of an overflow on `size`
if (mi_unlikely(req_size > (MI_LARGE_OBJ_SIZE_MAX - MI_EXTRA_PADDING_ARG) )) {
if (mi_unlikely(req_size > PTRDIFF_MAX)) { // we don't allocate more than PTRDIFF_MAX (see <https://sourceware.org/ml/libc-announce/2019/msg00001.html>)
_mi_error_message(EOVERFLOW, "allocation request is too large (%zu b requested)\n", req_size);
return NULL;
@ -823,7 +823,7 @@ void* _mi_malloc_generic(mi_heap_t* heap, size_t size MI_SOURCE_XPARAM) mi_attr_
}
else {
// otherwise find a page with free blocks in our size segregated queues
mi_assert_internal(size >= MI_PADDING_SIZE);
mi_assert_internal(size >= MI_EXTRA_PADDING_ARG);
page = mi_find_free_page(heap,size);
}
if (mi_unlikely(page == NULL)) { // out of memory
@ -835,5 +835,5 @@ void* _mi_malloc_generic(mi_heap_t* heap, size_t size MI_SOURCE_XPARAM) mi_attr_
mi_assert_internal(mi_page_block_size(page) >= size);
// and try again, this time succeeding! (i.e. this should never recurse)
return _mi_page_malloc(heap, page, size MI_SOURCE_XARG);
return _mi_page_malloc(heap, page, size MI_EXTRA_PADDING_XARG MI_SOURCE_XARG);
}