a347ea3787
Implement a free() that supports only the last malloc(). Rewind the heap to the last allocation point if the ptr to be freed is matching the end of heap before last malloc(). With current situation, since free() is no-op, every call to malloc() is a memory leak. BUG=b:140124451 TEST=Wrote a test function to do malloc and free operations. Change-Id: I6d43cf54b79e6897cf6882335730b2310e4eae45 Signed-off-by: Bora Guvendik <bora.guvendik@intel.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/37919 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Aaron Durbin <adurbin@chromium.org>
77 lines
1.9 KiB
C
77 lines
1.9 KiB
C
#include <stdlib.h>
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#include <console/console.h>
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#include <cpu/x86/smm.h>
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#if CONFIG(DEBUG_MALLOC)
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#define MALLOCDBG(x...) printk(BIOS_SPEW, x)
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#else
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#define MALLOCDBG(x...)
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#endif
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extern unsigned char _heap, _eheap;
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static void *free_mem_ptr = &_heap; /* Start of heap */
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static void *free_mem_end_ptr = &_eheap; /* End of heap */
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static void *free_last_alloc_ptr = &_heap; /* End of heap before
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last allocation */
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/* We don't restrict the boundary. This is firmware,
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* you are supposed to know what you are doing.
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*/
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void *memalign(size_t boundary, size_t size)
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{
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void *p;
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MALLOCDBG("%s Enter, boundary %zu, size %zu, free_mem_ptr %p\n",
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__func__, boundary, size, free_mem_ptr);
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free_mem_ptr = (void *)ALIGN((unsigned long)free_mem_ptr, boundary);
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p = free_mem_ptr;
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free_mem_ptr += size;
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/*
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* Store last allocation pointer after ALIGN, as malloc() will
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* return it. This may cause n bytes of gap between allocations
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* where n < boundary.
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*/
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free_last_alloc_ptr = p;
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if (free_mem_ptr >= free_mem_end_ptr) {
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printk(BIOS_ERR, "memalign(boundary=%zu, size=%zu): failed: ",
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boundary, size);
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printk(BIOS_ERR, "Tried to round up free_mem_ptr %p to %p\n",
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p, free_mem_ptr);
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printk(BIOS_ERR, "but free_mem_end_ptr is %p\n",
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free_mem_end_ptr);
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die("Error! memalign: Out of memory (free_mem_ptr >= free_mem_end_ptr)");
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}
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MALLOCDBG("memalign %p\n", p);
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return p;
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}
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void *malloc(size_t size)
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{
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return memalign(sizeof(u64), size);
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}
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void free(void *ptr)
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{
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if (ptr == NULL)
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return;
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if (ptr < (void *)&_heap || ptr >= free_mem_end_ptr) {
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printk(BIOS_WARNING, "Warning - Pointer passed to %s is not "
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"pointing to the heap\n", __func__);
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return;
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}
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/*
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* Rewind the heap pointer to the end of heap
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* before the last successful malloc().
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*/
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if (ptr == free_last_alloc_ptr) {
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free_mem_ptr = free_last_alloc_ptr;
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free_last_alloc_ptr = NULL;
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}
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}
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