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| //===-- xray_allocator.h ---------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file is a part of XRay, a dynamic runtime instrumentation system.
//
// Defines the allocator interface for an arena allocator, used primarily for
// the profiling runtime.
//
//===----------------------------------------------------------------------===//
#ifndef XRAY_ALLOCATOR_H
#define XRAY_ALLOCATOR_H
#include "sanitizer_common/sanitizer_common.h"
#include "sanitizer_common/sanitizer_internal_defs.h"
#include "sanitizer_common/sanitizer_mutex.h"
#if SANITIZER_FUCHSIA
#include <zircon/process.h>
#include <zircon/status.h>
#include <zircon/syscalls.h>
#else
#include "sanitizer_common/sanitizer_posix.h"
#endif
#include "xray_defs.h"
#include "xray_utils.h"
#include <cstddef>
#include <cstdint>
#include <sys/mman.h>
namespace __xray {
// We implement our own memory allocation routine which will bypass the
// internal allocator. This allows us to manage the memory directly, using
// mmap'ed memory to back the allocators.
template <class T> T *allocate() XRAY_NEVER_INSTRUMENT {
uptr RoundedSize = RoundUpTo(sizeof(T), GetPageSizeCached());
#if SANITIZER_FUCHSIA
zx_handle_t Vmo;
zx_status_t Status = _zx_vmo_create(RoundedSize, 0, &Vmo);
if (Status != ZX_OK) {
if (Verbosity())
Report("XRay Profiling: Failed to create VMO of size %zu: %s\n",
sizeof(T), _zx_status_get_string(Status));
return nullptr;
}
uintptr_t B;
Status =
_zx_vmar_map(_zx_vmar_root_self(), ZX_VM_PERM_READ | ZX_VM_PERM_WRITE, 0,
Vmo, 0, sizeof(T), &B);
_zx_handle_close(Vmo);
if (Status != ZX_OK) {
if (Verbosity())
Report("XRay Profiling: Failed to map VMAR of size %zu: %s\n", sizeof(T),
_zx_status_get_string(Status));
return nullptr;
}
return reinterpret_cast<T *>(B);
#else
uptr B = internal_mmap(NULL, RoundedSize, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
int ErrNo = 0;
if (UNLIKELY(internal_iserror(B, &ErrNo))) {
if (Verbosity())
Report(
"XRay Profiling: Failed to allocate memory of size %d; Error = %d.\n",
RoundedSize, B);
return nullptr;
}
#endif
return reinterpret_cast<T *>(B);
}
template <class T> void deallocate(T *B) XRAY_NEVER_INSTRUMENT {
if (B == nullptr)
return;
uptr RoundedSize = RoundUpTo(sizeof(T), GetPageSizeCached());
#if SANITIZER_FUCHSIA
_zx_vmar_unmap(_zx_vmar_root_self(), reinterpret_cast<uintptr_t>(B),
RoundedSize);
#else
internal_munmap(B, RoundedSize);
#endif
}
template <class T = unsigned char>
T *allocateBuffer(size_t S) XRAY_NEVER_INSTRUMENT {
uptr RoundedSize = RoundUpTo(S * sizeof(T), GetPageSizeCached());
#if SANITIZER_FUCHSIA
zx_handle_t Vmo;
zx_status_t Status = _zx_vmo_create(RoundedSize, 0, &Vmo);
if (Status != ZX_OK) {
if (Verbosity())
Report("XRay Profiling: Failed to create VMO of size %zu: %s\n", S,
_zx_status_get_string(Status));
return nullptr;
}
uintptr_t B;
Status = _zx_vmar_map(_zx_vmar_root_self(),
ZX_VM_PERM_READ | ZX_VM_PERM_WRITE, 0, Vmo, 0, S, &B);
_zx_handle_close(Vmo);
if (Status != ZX_OK) {
if (Verbosity())
Report("XRay Profiling: Failed to map VMAR of size %zu: %s\n", S,
_zx_status_get_string(Status));
return nullptr;
}
#else
uptr B = internal_mmap(NULL, RoundedSize, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
int ErrNo = 0;
if (UNLIKELY(internal_iserror(B, &ErrNo))) {
if (Verbosity())
Report(
"XRay Profiling: Failed to allocate memory of size %d; Error = %d.\n",
RoundedSize, B);
return nullptr;
}
#endif
return reinterpret_cast<T *>(B);
}
template <class T> void deallocateBuffer(T *B, size_t S) XRAY_NEVER_INSTRUMENT {
if (B == nullptr)
return;
uptr RoundedSize = RoundUpTo(S * sizeof(T), GetPageSizeCached());
#if SANITIZER_FUCHSIA
_zx_vmar_unmap(_zx_vmar_root_self(), reinterpret_cast<uintptr_t>(B),
RoundedSize);
#else
internal_munmap(B, RoundedSize);
#endif
}
template <class T, class... U>
T *initArray(size_t N, U &&... Us) XRAY_NEVER_INSTRUMENT {
auto A = allocateBuffer<T>(N);
if (A != nullptr)
while (N > 0)
new (A + (--N)) T(std::forward<U>(Us)...);
return A;
}
/// The Allocator type hands out fixed-sized chunks of memory that are
/// cache-line aligned and sized. This is useful for placement of
/// performance-sensitive data in memory that's frequently accessed. The
/// allocator also self-limits the peak memory usage to a dynamically defined
/// maximum.
///
/// N is the lower-bound size of the block of memory to return from the
/// allocation function. N is used to compute the size of a block, which is
/// cache-line-size multiples worth of memory. We compute the size of a block by
/// determining how many cache lines worth of memory is required to subsume N.
///
/// The Allocator instance will manage its own memory acquired through mmap.
/// This severely constrains the platforms on which this can be used to POSIX
/// systems where mmap semantics are well-defined.
///
/// FIXME: Isolate the lower-level memory management to a different abstraction
/// that can be platform-specific.
template <size_t N> struct Allocator {
// The Allocator returns memory as Block instances.
struct Block {
/// Compute the minimum cache-line size multiple that is >= N.
static constexpr auto Size = nearest_boundary(N, kCacheLineSize);
void *Data;
};
private:
size_t MaxMemory{0};
unsigned char *BackingStore = nullptr;
unsigned char *AlignedNextBlock = nullptr;
size_t AllocatedBlocks = 0;
bool Owned;
SpinMutex Mutex{};
void *Alloc() XRAY_NEVER_INSTRUMENT {
SpinMutexLock Lock(&Mutex);
if (UNLIKELY(BackingStore == nullptr)) {
BackingStore = allocateBuffer(MaxMemory);
if (BackingStore == nullptr) {
if (Verbosity())
Report("XRay Profiling: Failed to allocate memory for allocator.\n");
return nullptr;
}
AlignedNextBlock = BackingStore;
// Ensure that NextBlock is aligned appropriately.
auto BackingStoreNum = reinterpret_cast<uintptr_t>(BackingStore);
auto AlignedNextBlockNum = nearest_boundary(
reinterpret_cast<uintptr_t>(AlignedNextBlock), kCacheLineSize);
if (diff(AlignedNextBlockNum, BackingStoreNum) > ptrdiff_t(MaxMemory)) {
deallocateBuffer(BackingStore, MaxMemory);
AlignedNextBlock = BackingStore = nullptr;
if (Verbosity())
Report("XRay Profiling: Cannot obtain enough memory from "
"preallocated region.\n");
return nullptr;
}
AlignedNextBlock = reinterpret_cast<unsigned char *>(AlignedNextBlockNum);
// Assert that AlignedNextBlock is cache-line aligned.
DCHECK_EQ(reinterpret_cast<uintptr_t>(AlignedNextBlock) % kCacheLineSize,
0);
}
if (((AllocatedBlocks + 1) * Block::Size) > MaxMemory)
return nullptr;
// Align the pointer we'd like to return to an appropriate alignment, then
// advance the pointer from where to start allocations.
void *Result = AlignedNextBlock;
AlignedNextBlock =
reinterpret_cast<unsigned char *>(AlignedNextBlock) + Block::Size;
++AllocatedBlocks;
return Result;
}
public:
explicit Allocator(size_t M) XRAY_NEVER_INSTRUMENT
: MaxMemory(RoundUpTo(M, kCacheLineSize)),
BackingStore(nullptr),
AlignedNextBlock(nullptr),
AllocatedBlocks(0),
Owned(true),
Mutex() {}
explicit Allocator(void *P, size_t M) XRAY_NEVER_INSTRUMENT
: MaxMemory(M),
BackingStore(reinterpret_cast<unsigned char *>(P)),
AlignedNextBlock(reinterpret_cast<unsigned char *>(P)),
AllocatedBlocks(0),
Owned(false),
Mutex() {}
Allocator(const Allocator &) = delete;
Allocator &operator=(const Allocator &) = delete;
Allocator(Allocator &&O) XRAY_NEVER_INSTRUMENT {
SpinMutexLock L0(&Mutex);
SpinMutexLock L1(&O.Mutex);
MaxMemory = O.MaxMemory;
O.MaxMemory = 0;
BackingStore = O.BackingStore;
O.BackingStore = nullptr;
AlignedNextBlock = O.AlignedNextBlock;
O.AlignedNextBlock = nullptr;
AllocatedBlocks = O.AllocatedBlocks;
O.AllocatedBlocks = 0;
Owned = O.Owned;
O.Owned = false;
}
Allocator &operator=(Allocator &&O) XRAY_NEVER_INSTRUMENT {
SpinMutexLock L0(&Mutex);
SpinMutexLock L1(&O.Mutex);
MaxMemory = O.MaxMemory;
O.MaxMemory = 0;
if (BackingStore != nullptr)
deallocateBuffer(BackingStore, MaxMemory);
BackingStore = O.BackingStore;
O.BackingStore = nullptr;
AlignedNextBlock = O.AlignedNextBlock;
O.AlignedNextBlock = nullptr;
AllocatedBlocks = O.AllocatedBlocks;
O.AllocatedBlocks = 0;
Owned = O.Owned;
O.Owned = false;
return *this;
}
Block Allocate() XRAY_NEVER_INSTRUMENT { return {Alloc()}; }
~Allocator() NOEXCEPT XRAY_NEVER_INSTRUMENT {
if (Owned && BackingStore != nullptr) {
deallocateBuffer(BackingStore, MaxMemory);
}
}
};
} // namespace __xray
#endif // XRAY_ALLOCATOR_H
|