82 lines
2.2 KiB
C
82 lines
2.2 KiB
C
#include <errno.h>
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#include "memory.h"
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#include "pages.h"
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#include "util.h"
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#define ALIGNMENT_CEILING(s, alignment) (((s) + (alignment - 1)) & ((~(alignment)) + 1))
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void *allocate_pages(size_t usable_size, size_t guard_size, bool unprotect) {
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size_t real_size;
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if (unlikely(__builtin_add_overflow(usable_size, guard_size * 2, &real_size))) {
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errno = ENOMEM;
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return NULL;
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}
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void *real = memory_map(real_size);
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if (unlikely(real == NULL)) {
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return NULL;
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}
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void *usable = (char *)real + guard_size;
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if (unprotect && unlikely(memory_protect_rw(usable, usable_size))) {
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memory_unmap(real, real_size);
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return NULL;
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}
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return usable;
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}
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void deallocate_pages(void *usable, size_t usable_size, size_t guard_size) {
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memory_unmap((char *)usable - guard_size, usable_size + guard_size * 2);
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}
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void *allocate_pages_aligned(size_t usable_size, size_t alignment, size_t guard_size) {
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usable_size = PAGE_CEILING(usable_size);
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if (unlikely(!usable_size)) {
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errno = ENOMEM;
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return NULL;
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}
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size_t alloc_size;
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if (unlikely(__builtin_add_overflow(usable_size, alignment - PAGE_SIZE, &alloc_size))) {
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errno = ENOMEM;
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return NULL;
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}
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size_t real_alloc_size;
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if (unlikely(__builtin_add_overflow(alloc_size, guard_size * 2, &real_alloc_size))) {
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errno = ENOMEM;
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return NULL;
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}
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void *real = memory_map(real_alloc_size);
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if (unlikely(real == NULL)) {
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return NULL;
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}
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void *usable = (char *)real + guard_size;
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size_t lead_size = ALIGNMENT_CEILING((uintptr_t)usable, alignment) - (uintptr_t)usable;
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size_t trail_size = alloc_size - lead_size - usable_size;
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void *base = (char *)usable + lead_size;
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if (unlikely(memory_protect_rw(base, usable_size))) {
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memory_unmap(real, real_alloc_size);
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return NULL;
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}
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if (lead_size) {
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if (unlikely(memory_unmap(real, lead_size))) {
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memory_unmap(real, real_alloc_size);
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return NULL;
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}
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}
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if (trail_size) {
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if (unlikely(memory_unmap((char *)base + usable_size + guard_size, trail_size))) {
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memory_unmap(real, real_alloc_size);
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return NULL;
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}
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}
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return base;
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}
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