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Implement virtual memory code for *nix and make generic

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gingerBill
2021-08-26 15:53:08 +01:00
parent 3e4d615983
commit 5053f0179c
1 changed files with 59 additions and 41 deletions
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100
src/common_memory.cpp
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@@ -127,17 +127,51 @@ void arena_free_all(Arena *arena) {
}
#if defined(GB_SYSTEM_WINDOWS)
struct WindowsMemoryBlock {
struct PlatformMemoryBlock {
MemoryBlock block; // IMPORTANT NOTE: must be at the start
WindowsMemoryBlock *prev, *next;
isize total_size;
PlatformMemoryBlock *prev, *next;
};
gb_global WindowsMemoryBlock global_windows_memory_block_sentinel;
PlatformMemoryBlock *platform_virtual_memory_alloc(isize total_size);
void platform_virtual_memory_free(PlatformMemoryBlock *block);
void platform_virtual_memory_protect(void *memory, isize size);
#if defined(GB_SYSTEM_WINDOWS)
PlatformMemoryBlock *platform_virtual_memory_alloc(isize total_size) {
PlatformMemoryBlock *pmblock = (PlatformMemoryBlock *)VirtualAlloc(0, total_size, MEM_RESERVE|MEM_COMMIT, PAGE_READWRITE);
GB_ASSERT_MSG(pmblock != nullptr, "Out of Virtual Memory, oh no...");
return pmblock;
}
void platform_virtual_memory_free(PlatformMemoryBlock *block) {
GB_ASSERT(VirtualFree(block, 0, MEM_RELEASE));
}
void platform_virtual_memory_protect(void *memory, isize size) {
DWORD old_protect = 0;
BOOL is_protected = VirtualProtect(memory, size, PAGE_NOACCESS, &old_protect);
GB_ASSERT(is_protected);
}
#else
PlatformMemoryBlock *platform_virtual_memory_alloc(isize total_size) {
PlatformMemoryBlock *pmblock = (PlatformMemoryBlock *)mmap(nullptr, total_size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
GB_ASSERT_MSG(pmblock != nullptr, "Out of Virtual Memory, oh no...");
return pmblock;
}
void platform_virtual_memory_free(PlatformMemoryBlock *block) {
isize size = block->total_size;
munmap(block, size);
}
void platform_virtual_memory_protect(void *memory, isize size) {
int err = mprotect(memory, size, PROT_NONE);
GB_ASSERT(err != 0);
}
#endif
gb_global PlatformMemoryBlock global_platform_memory_block_sentinel;
void platform_virtual_memory_init(void) {
global_windows_memory_block_sentinel.prev = &global_windows_memory_block_sentinel;
global_windows_memory_block_sentinel.next = &global_windows_memory_block_sentinel;
global_platform_memory_block_sentinel.prev = &global_platform_memory_block_sentinel;
global_platform_memory_block_sentinel.next = &global_platform_memory_block_sentinel;
SYSTEM_INFO sys_info = {};
GetSystemInfo(&sys_info);
@@ -148,8 +182,8 @@ void platform_virtual_memory_init(void) {
MemoryBlock *virtual_memory_alloc(isize size) {
isize const page_size = DEFAULT_PAGE_SIZE;
isize total_size = size + gb_size_of(WindowsMemoryBlock);
isize base_offset = gb_size_of(WindowsMemoryBlock);
isize total_size = size + gb_size_of(PlatformMemoryBlock);
isize base_offset = gb_size_of(PlatformMemoryBlock);
isize protect_offset = 0;
bool do_protection = false;
@@ -161,60 +195,44 @@ MemoryBlock *virtual_memory_alloc(isize size) {
do_protection = true;
}
WindowsMemoryBlock *wmblock = (WindowsMemoryBlock *)VirtualAlloc(0, total_size, MEM_RESERVE|MEM_COMMIT, PAGE_READWRITE);
GB_ASSERT_MSG(wmblock != nullptr, "Out of Virtual Memory, oh no...");
PlatformMemoryBlock *pmblock = platform_virtual_memory_alloc(total_size);
GB_ASSERT_MSG(pmblock != nullptr, "Out of Virtual Memory, oh no...");
wmblock->block.base = cast(u8 *)wmblock + base_offset;
pmblock->block.base = cast(u8 *)pmblock + base_offset;
// Should be zeroed
GB_ASSERT(wmblock->block.used == 0);
GB_ASSERT(wmblock->block.prev == nullptr);
GB_ASSERT(pmblock->block.used == 0);
GB_ASSERT(pmblock->block.prev == nullptr);
if (do_protection) {
DWORD old_protect = 0;
BOOL is_protected = VirtualProtect(cast(u8 *)wmblock + protect_offset, page_size, PAGE_NOACCESS, &old_protect);
GB_ASSERT(is_protected);
platform_virtual_memory_protect(cast(u8 *)pmblock + protect_offset, page_size);
}
wmblock->block.size = size;
pmblock->block.size = size;
pmblock->total_size = total_size;
WindowsMemoryBlock *sentinel = &global_windows_memory_block_sentinel;
PlatformMemoryBlock *sentinel = &global_platform_memory_block_sentinel;
mutex_lock(&global_memory_block_mutex);
wmblock->next = sentinel;
wmblock->prev = sentinel->prev;
wmblock->prev->next = wmblock;
wmblock->next->prev = wmblock;
pmblock->next = sentinel;
pmblock->prev = sentinel->prev;
pmblock->prev->next = pmblock;
pmblock->next->prev = pmblock;
mutex_unlock(&global_memory_block_mutex);
return &wmblock->block;
return &pmblock->block;
}
void virtual_memory_dealloc(MemoryBlock *block_to_free) {
WindowsMemoryBlock *block = cast(WindowsMemoryBlock *)block_to_free;
PlatformMemoryBlock *block = cast(PlatformMemoryBlock *)block_to_free;
if (block != nullptr) {
mutex_lock(&global_memory_block_mutex);
block->prev->next = block->next;
block->next->prev = block->prev;
mutex_unlock(&global_memory_block_mutex);
GB_ASSERT(VirtualFree(block, 0, MEM_RELEASE));
platform_virtual_memory_free(block);
}
}
#else
#error Implement 'virtual_memory_alloc' and 'virtual_memory_dealloc' on this platform
void platform_virtual_memory_init(void) {
}
MemoryBlock *virtual_memory_alloc(isize size) {
return nullptr;
}
void virtual_memory_dealloc(MemoryBlock *block) {
}
#endif