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use DirectAnonMMap in emergency allocator

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It is just more straightforward and cleaner than going via
LowLevelAllocators "default" pages allocator, which does direct mmap
thingy anyways.
This commit is contained in:
Aliaksey Kandratsenka 2024-03-27 13:54:18 -04:00
parent 6785aeb027
commit 7cbbbdd099
1 changed files with 7 additions and 5 deletions
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12
src/emergency_malloc.cc
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@ -33,6 +33,8 @@
#include "emergency_malloc.h"
#include <tuple>
#include <errno.h> // for ENOMEM, errno
#include <string.h> // for memset
@ -41,6 +43,7 @@
#include "base/low_level_alloc.h"
#include "base/spinlock.h"
#include "internal_logging.h"
#include "mmap_hook.h"
#include "thread_cache_ptr.h"
namespace tcmalloc {
@ -69,9 +72,8 @@ class EmergencyArenaPagesAllocator : public LowLevelAlloc::PagesAllocator {
};
static void InitEmergencyMalloc(void) {
constexpr int32_t flags = LowLevelAlloc::kAsyncSignalSafe;
void *arena = LowLevelAlloc::GetDefaultPagesAllocator()->MapPages(flags, kEmergencyArenaSize * 2);
auto [arena, success] = DirectAnonMMap(false, kEmergencyArenaSize * 2);
CHECK_CONDITION(success);
uintptr_t arena_ptr = reinterpret_cast<uintptr_t>(arena);
uintptr_t ptr = (arena_ptr + kEmergencyArenaSize - 1) & ~(kEmergencyArenaSize-1);
@ -90,12 +92,12 @@ static void InitEmergencyMalloc(void) {
uintptr_t head_unmap_size = ptr - arena_ptr;
CHECK_CONDITION(head_unmap_size < kEmergencyArenaSize);
if (head_unmap_size != 0) {
LowLevelAlloc::GetDefaultPagesAllocator()->UnMapPages(flags, arena, ptr - arena_ptr);
DirectMUnMap(false, arena, ptr - arena_ptr);
}
uintptr_t tail_unmap_size = kEmergencyArenaSize - head_unmap_size;
void *tail_start = reinterpret_cast<void *>(arena_ptr + head_unmap_size + kEmergencyArenaSize);
LowLevelAlloc::GetDefaultPagesAllocator()->UnMapPages(flags, tail_start, tail_unmap_size);
DirectMUnMap(false, tail_start, tail_unmap_size);
}
ATTRIBUTE_HIDDEN void *EmergencyMalloc(size_t size) {