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Try to merge tail with next block when splitting

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When splitting a memory block, check if the next block is free.
If it is, then just extend it upwards instead of creating a new block.
This fixes a bug where when shrinking existing allocations would result in irreversible free space fragmentation.

When testing on the host, test all the poisoning configurations.
This commit is contained in:
Deomid Ryabkov 2018-03-22 14:58:20 +00:00 committed by Angus Gratton
parent 4e36ede3bf
commit 712bd1d773
6 changed files with 221 additions and 79 deletions
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73
components/heap/multi_heap.c
View file

@ -123,6 +123,12 @@ static inline bool is_free(const heap_block_t *block)
return block->header & BLOCK_FREE_FLAG;
}
/* Return true if this block is the first in the heap */
static inline bool is_first_block(const heap_t *heap, const heap_block_t *block)
{
return (block == &heap->first_block);
}
/* Return true if this block is the last_block in the heap
(the only block with no next pointer) */
static inline bool is_last_block(const heap_block_t *block)
@ -167,7 +173,7 @@ static void assert_valid_block(const heap_t *heap, const heap_block_t *block)
*/
static heap_block_t *get_prev_free_block(heap_t *heap, const heap_block_t *block)
{
assert(block != &heap->first_block); /* can't look for a block before first_block */
assert(!is_first_block(heap, block)); /* can't look for a block before first_block */
for (heap_block_t *b = &heap->first_block; b != NULL && b < block; b = b->next_free) {
MULTI_HEAP_ASSERT(is_free(b), b); // Block should be free
@ -198,7 +204,7 @@ static heap_block_t *merge_adjacent(heap_t *heap, heap_block_t *a, heap_block_t
if (is_last_block(b)) {
return a;
}
if (a == &heap->first_block) {
if (is_first_block(heap, a)) {
return b;
}
@ -250,33 +256,52 @@ static heap_block_t *merge_adjacent(heap_t *heap, heap_block_t *a, heap_block_t
*/
static void split_if_necessary(heap_t *heap, heap_block_t *block, size_t size, heap_block_t *prev_free_block)
{
const size_t block_size = block_data_size(block);
MULTI_HEAP_ASSERT(!is_free(block), block); // split block shouldn't be free
MULTI_HEAP_ASSERT(size <= block_data_size(block), block); // size should be valid
MULTI_HEAP_ASSERT(size <= block_size, block); // size should be valid
size = ALIGN_UP(size);
/* can't split the head or tail block */
assert(block != &heap->first_block);
assert(!is_first_block(heap, block));
assert(!is_last_block(block));
if (block_data_size(block) < size + sizeof(heap_block_t)) {
/* Can't split 'block' if we're not going to get a usable free block afterwards */
return;
}
/* Block is larger than it needs to be, insert a new free block after it */
heap_block_t *new_block = (heap_block_t *)(block->data + size);
new_block->header = block->header | BLOCK_FREE_FLAG;
block->header = (intptr_t)new_block;
heap_block_t *next_block = get_next_block(block);
if (prev_free_block == NULL) {
prev_free_block = get_prev_free_block(heap, block);
if (is_free(next_block) && !is_last_block(next_block)) {
/* The next block is free, just extend it upwards. */
new_block->header = next_block->header;
new_block->next_free = next_block->next_free;
if (prev_free_block == NULL) {
prev_free_block = get_prev_free_block(heap, block);
}
/* prev_free_block should point to the next block (which we found to be free). */
MULTI_HEAP_ASSERT(prev_free_block->next_free == next_block,
&prev_free_block->next_free); // free blocks should be in order
/* Note: We have not introduced a new block header, hence the simple math. */
heap->free_bytes += block_size - size;
#ifdef MULTI_HEAP_POISONING_SLOW
/* next_block header needs to be replaced with a fill pattern */
multi_heap_internal_poison_fill_region(next_block, sizeof(heap_block_t), true /* free */);
#endif
} else {
/* Insert a free block between the current and the next one. */
if (block_data_size(block) < size + sizeof(heap_block_t)) {
/* Can't split 'block' if we're not going to get a usable free block afterwards */
return;
}
if (prev_free_block == NULL) {
prev_free_block = get_prev_free_block(heap, block);
}
new_block->header = block->header | BLOCK_FREE_FLAG;
new_block->next_free = prev_free_block->next_free;
/* prev_free_block should point to a free block after new_block */
MULTI_HEAP_ASSERT(prev_free_block->next_free > new_block,
&prev_free_block->next_free); // free blocks should be in order
heap->free_bytes += block_data_size(new_block);
}
/* prev_free_block should point to a free block after new_block */
MULTI_HEAP_ASSERT(prev_free_block->next_free > new_block,
&prev_free_block->next_free); // free blocks should be in order
new_block->next_free = prev_free_block->next_free;
block->header = (intptr_t)new_block;
prev_free_block->next_free = new_block;
heap->free_bytes += block_data_size(new_block);
}
size_t multi_heap_get_allocated_size_impl(multi_heap_handle_t heap, void *p)
@ -414,7 +439,7 @@ void multi_heap_free_impl(multi_heap_handle_t heap, void *p)
assert_valid_block(heap, pb);
MULTI_HEAP_ASSERT(!is_free(pb), pb); // block should not be free
MULTI_HEAP_ASSERT(!is_last_block(pb), pb); // block should not be last block
MULTI_HEAP_ASSERT(pb != &heap->first_block, pb); // block should not be first block
MULTI_HEAP_ASSERT(!is_first_block(heap, pb), pb); // block should not be first block
heap_block_t *next = get_next_block(pb);
@ -570,19 +595,21 @@ bool multi_heap_check(multi_heap_handle_t heap, bool print_errors)
FAIL_PRINT("CORRUPT HEAP: Block %p is outside heap (last valid block %p)\n", b, prev);
goto done;
}
prev = b;
if (is_free(b)) {
if (prev != NULL && is_free(prev) && !is_first_block(heap, prev) && !is_last_block(b)) {
FAIL_PRINT("CORRUPT HEAP: Two adjacent free blocks found, %p and %p\n", prev, b);
}
if (expected_free != NULL && expected_free != b) {
FAIL_PRINT("CORRUPT HEAP: Prev free block %p pointed to next free %p but this free block is %p\n",
prev_free, expected_free, b);
}
prev_free = b;
expected_free = b->next_free;
if (b != &heap->first_block) {
if (!is_first_block(heap, b)) {
total_free_bytes += block_data_size(b);
}
}
prev = b;
#ifdef MULTI_HEAP_POISONING
if (!is_last_block(b)) {

10
components/heap/multi_heap_config.h
View file

@ -14,8 +14,8 @@
#pragma once
#ifdef ESP_PLATFORM
#include "sdkconfig.h"
#endif
/* Configuration macros for multi-heap */
@ -27,11 +27,3 @@
#define MULTI_HEAP_POISONING
#define MULTI_HEAP_POISONING_SLOW
#endif
#else /* !ESP_PLATFORM */
/* Host-side tests, enable full poisoning */
#define MULTI_HEAP_POISONING
#define MULTI_HEAP_POISONING_SLOW
#endif

2
components/heap/multi_heap_poisoning.c
View file

@ -242,6 +242,8 @@ void *multi_heap_realloc(multi_heap_handle_t heap, void *p, size_t size)
place.)
For now we just malloc a new buffer, copy, and free. :|
Note: If this ever changes, multi_heap defrag realloc test should be enabled.
*/
size_t orig_alloc_size = head->alloc_size;

59
components/heap/test_multi_heap_host/Makefile
View file

@ -1,49 +1,18 @@
TEST_PROGRAM=test_multi_heap
all: $(TEST_PROGRAM)
test: test_poisoning_disabled \
test_poisoning_light \
test_poisoning_comprehensive
SOURCE_FILES = $(abspath \
../multi_heap.c \
../multi_heap_poisoning.c \
test_multi_heap.cpp \
main.cpp \
)
test_poisoning_disabled:
@echo ==== HEAP_POISONING_DISABLED ====
CPPFLAGS= $(MAKE) -f Makefile.test clean test
INCLUDE_FLAGS = -I../include -I../../../tools/catch
test_poisoning_light:
@echo ==== HEAP_POISONING_LIGHT ====
CPPFLAGS=-DCONFIG_HEAP_POISONING_LIGHT $(MAKE) -f Makefile.test clean test
GCOV ?= gcov
test_poisoning_comprehensive:
@echo ==== HEAP_POISONING_COMPREHENSIVE ====
CPPFLAGS=-DCONFIG_HEAP_POISONING_COMPREHENSIVE $(MAKE) -f Makefile.test clean test
CPPFLAGS += $(INCLUDE_FLAGS) -D CONFIG_LOG_DEFAULT_LEVEL -g -fstack-protector-all -m32
CFLAGS += -Wall -Werror -fprofile-arcs -ftest-coverage
CXXFLAGS += -std=c++11 -Wall -Werror -fprofile-arcs -ftest-coverage
LDFLAGS += -lstdc++ -fprofile-arcs -ftest-coverage -m32
OBJ_FILES = $(filter %.o, $(SOURCE_FILES:.cpp=.o) $(SOURCE_FILES:.c=.o))
COVERAGE_FILES = $(OBJ_FILES:.o=.gc*)
$(TEST_PROGRAM): $(OBJ_FILES)
g++ $(LDFLAGS) -o $(TEST_PROGRAM) $(OBJ_FILES)
$(OUTPUT_DIR):
mkdir -p $(OUTPUT_DIR)
test: $(TEST_PROGRAM)
./$(TEST_PROGRAM)
$(COVERAGE_FILES): $(TEST_PROGRAM) test
coverage.info: $(COVERAGE_FILES)
find ../ -name "*.gcno" -exec $(GCOV) -r -pb {} +
lcov --capture --directory $(abspath ../) --no-external --output-file coverage.info --gcov-tool $(GCOV)
coverage_report: coverage.info
genhtml coverage.info --output-directory coverage_report
@echo "Coverage report is in coverage_report/index.html"
clean:
rm -f $(OBJ_FILES) $(TEST_PROGRAM)
rm -f $(COVERAGE_FILES) *.gcov
rm -rf coverage_report/
rm -f coverage.info
.PHONY: clean all test
%:
CPPFLAGS=-DCONFIG_HEAP_POISONING_COMPREHENSIVE $(MAKE) -f Makefile.test $@

49
components/heap/test_multi_heap_host/Makefile.test Normal file
View file

@ -0,0 +1,49 @@
TEST_PROGRAM=test_multi_heap
all: $(TEST_PROGRAM)
SOURCE_FILES = $(abspath \
../multi_heap.c \
../multi_heap_poisoning.c \
test_multi_heap.cpp \
main.cpp \
)
INCLUDE_FLAGS = -I../include -I../../../tools/catch
GCOV ?= gcov
CPPFLAGS += $(INCLUDE_FLAGS) -D CONFIG_LOG_DEFAULT_LEVEL -g -fstack-protector-all -m32
CFLAGS += -Wall -Werror -fprofile-arcs -ftest-coverage
CXXFLAGS += -std=c++11 -Wall -Werror -fprofile-arcs -ftest-coverage
LDFLAGS += -lstdc++ -fprofile-arcs -ftest-coverage -m32
OBJ_FILES = $(filter %.o, $(SOURCE_FILES:.cpp=.o) $(SOURCE_FILES:.c=.o))
COVERAGE_FILES = $(OBJ_FILES:.o=.gc*)
$(TEST_PROGRAM): $(OBJ_FILES)
g++ $(LDFLAGS) -o $(TEST_PROGRAM) $(OBJ_FILES)
$(OUTPUT_DIR):
mkdir -p $(OUTPUT_DIR)
test: $(TEST_PROGRAM)
./$(TEST_PROGRAM)
$(COVERAGE_FILES): $(TEST_PROGRAM) test
coverage.info: $(COVERAGE_FILES)
find ../ -name "*.gcno" -exec $(GCOV) -r -pb {} +
lcov --capture --directory $(abspath ../) --no-external --output-file coverage.info --gcov-tool $(GCOV)
coverage_report: coverage.info
genhtml coverage.info --output-directory coverage_report
@echo "Coverage report is in coverage_report/index.html"
clean:
rm -f $(OBJ_FILES) $(TEST_PROGRAM)
rm -f $(COVERAGE_FILES) *.gcov
rm -rf coverage_report/
rm -f coverage.info
.PHONY: clean all test

107
components/heap/test_multi_heap_host/test_multi_heap.cpp
View file

@ -76,7 +76,7 @@ TEST_CASE("multi_heap fragmentation", "[multi_heap]")
printf("allocated %p %p %p %p\n", p[0], p[1], p[2], p[3]);
REQUIRE( multi_heap_malloc(heap, alloc_size * 3) == NULL ); /* no room to allocate 3*alloc_size now */
REQUIRE( multi_heap_malloc(heap, alloc_size * 5) == NULL ); /* no room to allocate 5*alloc_size now */
printf("4 allocations:\n");
multi_heap_dump(heap);
@ -105,6 +105,103 @@ TEST_CASE("multi_heap fragmentation", "[multi_heap]")
multi_heap_free(heap, big);
}
/* Test that malloc/free does not leave free space fragmented */
TEST_CASE("multi_heap defrag", "[multi_heap]")
{
void *p[4];
uint8_t small_heap[512];
multi_heap_info_t info, info2;
multi_heap_handle_t heap = multi_heap_register(small_heap, sizeof(small_heap));
printf("0 ---\n");
multi_heap_dump(heap);
REQUIRE( multi_heap_check(heap, true) );
multi_heap_get_info(heap, &info);
REQUIRE( 0 == info.allocated_blocks );
REQUIRE( 1 == info.free_blocks );
printf("1 ---\n");
p[0] = multi_heap_malloc(heap, 128);
p[1] = multi_heap_malloc(heap, 32);
multi_heap_dump(heap);
REQUIRE( multi_heap_check(heap, true) );
printf("2 ---\n");
multi_heap_free(heap, p[0]);
p[2] = multi_heap_malloc(heap, 64);
multi_heap_dump(heap);
REQUIRE( p[2] == p[0] );
REQUIRE( multi_heap_check(heap, true) );
printf("3 ---\n");
multi_heap_free(heap, p[2]);
p[3] = multi_heap_malloc(heap, 32);
multi_heap_dump(heap);
REQUIRE( p[3] == p[0] );
REQUIRE( multi_heap_check(heap, true) );
multi_heap_get_info(heap, &info2);
REQUIRE( 2 == info2.allocated_blocks );
REQUIRE( 2 == info2.free_blocks );
multi_heap_free(heap, p[0]);
multi_heap_free(heap, p[1]);
multi_heap_get_info(heap, &info2);
REQUIRE( 0 == info2.allocated_blocks );
REQUIRE( 1 == info2.free_blocks );
REQUIRE( info.total_free_bytes == info2.total_free_bytes );
}
/* Test that malloc/free does not leave free space fragmented
Note: With fancy poisoning, realloc is implemented as malloc-copy-free and this test does not apply.
*/
#ifndef MULTI_HEAP_POISONING_SLOW
TEST_CASE("multi_heap defrag realloc", "[multi_heap]")
{
void *p[4];
uint8_t small_heap[512];
multi_heap_info_t info, info2;
multi_heap_handle_t heap = multi_heap_register(small_heap, sizeof(small_heap));
printf("0 ---\n");
multi_heap_dump(heap);
REQUIRE( multi_heap_check(heap, true) );
multi_heap_get_info(heap, &info);
REQUIRE( 0 == info.allocated_blocks );
REQUIRE( 1 == info.free_blocks );
printf("1 ---\n");
p[0] = multi_heap_malloc(heap, 128);
p[1] = multi_heap_malloc(heap, 32);
multi_heap_dump(heap);
REQUIRE( multi_heap_check(heap, true) );
printf("2 ---\n");
p[2] = multi_heap_realloc(heap, p[0], 64);
multi_heap_dump(heap);
REQUIRE( p[2] == p[0] );
REQUIRE( multi_heap_check(heap, true) );
printf("3 ---\n");
p[3] = multi_heap_realloc(heap, p[2], 32);
multi_heap_dump(heap);
REQUIRE( p[3] == p[0] );
REQUIRE( multi_heap_check(heap, true) );
multi_heap_get_info(heap, &info2);
REQUIRE( 2 == info2.allocated_blocks );
REQUIRE( 2 == info2.free_blocks );
multi_heap_free(heap, p[0]);
multi_heap_free(heap, p[1]);
multi_heap_get_info(heap, &info2);
REQUIRE( 0 == info2.allocated_blocks );
REQUIRE( 1 == info2.free_blocks );
REQUIRE( info.total_free_bytes == info2.total_free_bytes );
}
#endif
TEST_CASE("multi_heap many random allocations", "[multi_heap]")
{
uint8_t big_heap[1024];
@ -329,7 +426,13 @@ TEST_CASE("multi_heap_realloc()", "[multi_heap]")
REQUIRE( multi_heap_check(heap, true) );
REQUIRE( f == b ); /* 'b' should be extended in-place, over space formerly occupied by 'd' */
uint32_t *g = (uint32_t *)multi_heap_realloc(heap, e, 128); /* not enough contiguous space left in the heap */
#ifdef MULTI_HEAP_POISONING
#define TOO_MUCH 92 + 1
#else
#define TOO_MUCH 128 + 1
#endif
/* not enough contiguous space left in the heap */
uint32_t *g = (uint32_t *)multi_heap_realloc(heap, e, TOO_MUCH);
REQUIRE( g == NULL );
multi_heap_free(heap, f);