[libc-commits] [libc] [libc] add basic arena allocator (PR #121173)
via libc-commits
libc-commits at lists.llvm.org
Thu Dec 26 17:49:23 PST 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-libc
Author: Tristan Ross (RossComputerGuy)
<details>
<summary>Changes</summary>
This PR adds support for multiple allocator implementations. This will be beneficial for distros and embedded systems where different kinds of allocators can be better than others. To start out with, I just added a primitive arena allocator. This PR also adds `getpagesize` which supports dynamic and static page sizes.
---
Patch is 31.20 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/121173.diff
36 Files Affected:
- (modified) libc/CMakeLists.txt (+6)
- (modified) libc/config/config.json (+10)
- (modified) libc/config/linux/aarch64/entrypoints.txt (+1)
- (modified) libc/config/linux/riscv/entrypoints.txt (+1)
- (modified) libc/docs/configure.rst (+3)
- (modified) libc/hdrgen/yaml/unistd.yaml (+6)
- (modified) libc/src/__support/CMakeLists.txt (+2)
- (added) libc/src/__support/alloc/CMakeLists.txt (+57)
- (added) libc/src/__support/alloc/alloc.cpp (+13)
- (added) libc/src/__support/alloc/alloc.h (+22)
- (added) libc/src/__support/alloc/arena.cpp (+71)
- (added) libc/src/__support/alloc/arena.h (+47)
- (added) libc/src/__support/alloc/baremetal/CMakeLists.txt (+13)
- (added) libc/src/__support/alloc/baremetal/page.cpp (+22)
- (added) libc/src/__support/alloc/base.cpp (+16)
- (added) libc/src/__support/alloc/base.h (+44)
- (added) libc/src/__support/alloc/linux/CMakeLists.txt (+16)
- (added) libc/src/__support/alloc/linux/page.cpp (+41)
- (added) libc/src/__support/alloc/page.h (+23)
- (modified) libc/src/__support/macros/CMakeLists.txt (+6)
- (added) libc/src/__support/macros/page_size.h (+17)
- (modified) libc/src/__support/memory_size.h (+14)
- (modified) libc/src/stdlib/CMakeLists.txt (+51)
- (added) libc/src/stdlib/aligned_alloc.cpp (+12)
- (added) libc/src/stdlib/calloc.cpp (+12)
- (added) libc/src/stdlib/free.cpp (+13)
- (added) libc/src/stdlib/malloc.cpp (+13)
- (added) libc/src/stdlib/realloc.cpp (+12)
- (modified) libc/src/unistd/CMakeLists.txt (+29)
- (added) libc/src/unistd/generic/CMakeLists.txt (+12)
- (added) libc/src/unistd/generic/getpagesize.cpp (+22)
- (added) libc/src/unistd/getpagesize.h (+20)
- (modified) libc/src/unistd/linux/CMakeLists.txt (+13)
- (added) libc/src/unistd/linux/getpagesize.cpp (+29)
- (modified) libc/test/src/unistd/CMakeLists.txt (+10)
- (added) libc/test/src/unistd/getpagesize_test.cpp (+16)
``````````diff
diff --git a/libc/CMakeLists.txt b/libc/CMakeLists.txt
index 00a07ea3c8ac75..eebab925ba489d 100644
--- a/libc/CMakeLists.txt
+++ b/libc/CMakeLists.txt
@@ -386,6 +386,12 @@ else()
set(libc_opt_high_flag "-O3")
endif()
+if(${LIBC_CONF_ALLOC_TYPE} MATCHES "LIBC_ALLOC_TYPE_SCUDO")
+ set(LLVM_LIBC_INCLUDE_SCUDO ON)
+elseif(LLVM_LIBC_INCLUDE_SCUDO)
+ message(FATAL_ERROR "Cannot include scudo and use a different allocator.")
+endif()
+
add_subdirectory(include)
add_subdirectory(config)
add_subdirectory(hdr)
diff --git a/libc/config/config.json b/libc/config/config.json
index 9a5d5c3c68da60..6017d2e004de3e 100644
--- a/libc/config/config.json
+++ b/libc/config/config.json
@@ -115,6 +115,16 @@
"LIBC_ADD_NULL_CHECKS": {
"value": true,
"doc": "Add nullptr checks in the library's implementations to some functions for which passing nullptr is undefined behavior."
+ },
+ "LIBC_CONF_ALLOC_TYPE": {
+ "value": "LIBC_ALLOC_TYPE_ARENA",
+ "doc": "The implementation used for allocations, acceptable values are LIBC_ALLOC_TYPE_EXTERN, LIBC_ALLOC_TYPE_SCUDO, LIBC_ALLOC_TYPE_ARENA."
+ }
+ },
+ "unistd": {
+ "LIBC_CONF_PAGE_SIZE": {
+ "value": "LIBC_PAGE_SIZE_SYSTEM",
+ "doc": "The value to use for the system page size, acceptable values are LIBC_CONF_PAGE_SIZE_SYSTEM, LIBC_CONF_PAGE_SIZE_4K, LIBC_CONF_PAGE_SIZE_16K, LIBC_CONF_PAGE_SIZE_64K."
}
}
}
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 00f0c6a8bfb8e4..ce67118545c9a5 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -323,6 +323,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.unistd.ftruncate
libc.src.unistd.getcwd
libc.src.unistd.geteuid
+ libc.src.unistd.getpagesize
libc.src.unistd.getpid
libc.src.unistd.getppid
libc.src.unistd.gettid
diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
index 49a8d61b938027..3b53396b5943b2 100644
--- a/libc/config/linux/riscv/entrypoints.txt
+++ b/libc/config/linux/riscv/entrypoints.txt
@@ -320,6 +320,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.unistd.ftruncate
libc.src.unistd.getcwd
libc.src.unistd.geteuid
+ libc.src.unistd.getpagesize
libc.src.unistd.getpid
libc.src.unistd.getppid
libc.src.unistd.gettid
diff --git a/libc/docs/configure.rst b/libc/docs/configure.rst
index 3db750b1aed214..036e8fc7a93832 100644
--- a/libc/docs/configure.rst
+++ b/libc/docs/configure.rst
@@ -32,6 +32,7 @@ to learn about the defaults for your platform and target.
- ``LIBC_CONF_ERRNO_MODE``: The implementation used for errno, acceptable values are LIBC_ERRNO_MODE_DEFAULT, LIBC_ERRNO_MODE_UNDEFINED, LIBC_ERRNO_MODE_THREAD_LOCAL, LIBC_ERRNO_MODE_SHARED, LIBC_ERRNO_MODE_EXTERNAL, and LIBC_ERRNO_MODE_SYSTEM.
* **"general" options**
- ``LIBC_ADD_NULL_CHECKS``: Add nullptr checks in the library's implementations to some functions for which passing nullptr is undefined behavior.
+ - ``LIBC_CONF_ALLOC_TYPE``: The implementation used for allocations, acceptable values are LIBC_ALLOC_TYPE_EXTERN, LIBC_ALLOC_TYPE_SCUDO, LIBC_ALLOC_TYPE_ARENA.
* **"math" options**
- ``LIBC_CONF_FREXP_INF_NAN_EXPONENT``: The value written back to the second parameter when calling frexp/frexpf/frexpl` with `+/-Inf`/`NaN` is unspecified. Configue an explicit exp value for Inf/NaN inputs.
- ``LIBC_CONF_MATH_OPTIMIZATIONS``: Configures optimizations for math functions. Values accepted are LIBC_MATH_SKIP_ACCURATE_PASS, LIBC_MATH_SMALL_TABLES, LIBC_MATH_NO_ERRNO, LIBC_MATH_NO_EXCEPT, and LIBC_MATH_FAST.
@@ -60,3 +61,5 @@ to learn about the defaults for your platform and target.
- ``LIBC_CONF_STRING_UNSAFE_WIDE_READ``: Read more than a byte at a time to perform byte-string operations like strlen.
* **"time" options**
- ``LIBC_CONF_TIME_64BIT``: Force the size of time_t to 64 bits, even on platforms where compatibility considerations would otherwise make it 32-bit.
+* **"unistd" options**
+ - ``LIBC_CONF_PAGE_SIZE``: The value to use for the system page size, acceptable values are LIBC_CONF_PAGE_SIZE_SYSTEM, LIBC_CONF_PAGE_SIZE_4K, LIBC_CONF_PAGE_SIZE_16K, LIBC_CONF_PAGE_SIZE_64K.
diff --git a/libc/hdrgen/yaml/unistd.yaml b/libc/hdrgen/yaml/unistd.yaml
index c6441c04ce3a3d..a044a4290aed85 100644
--- a/libc/hdrgen/yaml/unistd.yaml
+++ b/libc/hdrgen/yaml/unistd.yaml
@@ -141,6 +141,12 @@ functions:
- type: int
- type: __getoptargv_t
- type: const char *
+ - name: getpagesize
+ standards:
+ - POSIX
+ return_type: int
+ arguments:
+ - type: void
- name: getpid
standards:
- POSIX
diff --git a/libc/src/__support/CMakeLists.txt b/libc/src/__support/CMakeLists.txt
index 4e90aad9a45b40..45f4dde264122a 100644
--- a/libc/src/__support/CMakeLists.txt
+++ b/libc/src/__support/CMakeLists.txt
@@ -370,3 +370,5 @@ add_subdirectory(HashTable)
add_subdirectory(fixed_point)
add_subdirectory(time)
+
+add_subdirectory(alloc)
diff --git a/libc/src/__support/alloc/CMakeLists.txt b/libc/src/__support/alloc/CMakeLists.txt
new file mode 100644
index 00000000000000..f7142bb0d7c0b8
--- /dev/null
+++ b/libc/src/__support/alloc/CMakeLists.txt
@@ -0,0 +1,57 @@
+add_object_library(
+ base
+ SRCS
+ base.cpp
+ HDRS
+ base.h
+ DEPENDS
+ libc.hdr.types.size_t
+ libc.src.__support.macros.config
+)
+
+if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_OS})
+ add_subdirectory(${LIBC_TARGET_OS})
+endif()
+
+if(TARGET libc.src.__support.alloc.${LIBC_TARGET_OS}.page)
+ add_object_library(
+ page
+ ALIAS
+ DEPENDS
+ .${LIBC_TARGET_OS}.page
+ )
+endif()
+
+add_object_library(
+ arena
+ SRCS
+ arena.cpp
+ HDRS
+ arena.h
+ COMPILE_OPTIONS
+ -DLIBC_PAGE_SIZE=${LIBC_CONF_PAGE_SIZE}
+ DEPENDS
+ .base
+ .page
+ libc.include.llvm-libc-macros.stdint_macros
+ libc.src.string.memmove
+ libc.src.unistd.getpagesize
+)
+
+if(NOT ${LIBC_CONF_ALLOC_TYPE} MATCHES "LIBC_ALLOC_TYPE_SCUDO" AND NOT ${LIBC_CONF_ALLOC_TYPE} MATCHES "LIBC_ALLOC_TYPE_EXTERN")
+ string(TOLOWER ${LIBC_CONF_ALLOC_TYPE} LIBC_CONF_ALLOC_TYPE_NAME)
+ string(REPLACE "libc_alloc_type_" "" LIBC_CONF_ALLOC_TYPE_NAME "${LIBC_CONF_ALLOC_TYPE_NAME}")
+ if(TARGET libc.src.__support.alloc.${LIBC_CONF_ALLOC_TYPE_NAME})
+ add_object_library(
+ alloc
+ SRCS
+ alloc.cpp
+ HDRS
+ alloc.h
+ COMPILE_OPTIONS
+ -DLIBC_CONF_ALLOC_TYPE=${LIBC_CONF_ALLOC_TYPE_NAME}
+ DEPENDS
+ .${LIBC_CONF_ALLOC_TYPE_NAME}
+ )
+ endif()
+endif()
diff --git a/libc/src/__support/alloc/alloc.cpp b/libc/src/__support/alloc/alloc.cpp
new file mode 100644
index 00000000000000..f5f1832bb58a8f
--- /dev/null
+++ b/libc/src/__support/alloc/alloc.cpp
@@ -0,0 +1,13 @@
+#include <src/__support/alloc/alloc.h>
+#include <src/__support/alloc/arena.h>
+
+namespace LIBC_NAMESPACE_DECL {
+
+#define CONCAT(a, b) a##b
+#define EXPAND_AND_CONCAT(a, b) CONCAT(a, b)
+
+#define ALLOCATOR EXPAND_AND_CONCAT(LIBC_CONF_ALLOC_TYPE, _allocator)
+
+BaseAllocator *allocator = reinterpret_cast<BaseAllocator *>(&ALLOCATOR);
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/__support/alloc/alloc.h b/libc/src/__support/alloc/alloc.h
new file mode 100644
index 00000000000000..88b5fbfb84680f
--- /dev/null
+++ b/libc/src/__support/alloc/alloc.h
@@ -0,0 +1,22 @@
+//===-- libc-wide allocator -------------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_ALLOC_ALLOC_H
+#define LLVM_LIBC_SRC___SUPPORT_ALLOC_ALLOC_H
+
+#include "src/__support/alloc/base.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+// The primary allocator to use
+extern BaseAllocator *allocator;
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif
diff --git a/libc/src/__support/alloc/arena.cpp b/libc/src/__support/alloc/arena.cpp
new file mode 100644
index 00000000000000..f39d80630f2477
--- /dev/null
+++ b/libc/src/__support/alloc/arena.cpp
@@ -0,0 +1,71 @@
+#include "src/__support/alloc/arena.h"
+#include "src/__support/alloc/page.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/page_size.h"
+#include "src/__support/memory_size.h"
+#include "src/string/memmove.h"
+#include "src/unistd/getpagesize.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+void *arena_allocate(BaseAllocator *base, size_t alignment, size_t size) {
+ ArenaAllocator *self = reinterpret_cast<ArenaAllocator *>(base);
+
+ if (self->buffer == nullptr) {
+ self->buffer = reinterpret_cast<uint8_t *>(page_allocate(1));
+ self->buffer_size = self->get_page_size();
+ }
+
+ uintptr_t curr_ptr = (uintptr_t)self->buffer + (uintptr_t)self->curr_offset;
+ uintptr_t offset = internal::align_forward<uintptr_t>(curr_ptr, alignment);
+ offset -= (uintptr_t)self->buffer;
+
+ if (offset + size > self->buffer_size) {
+ self->buffer = reinterpret_cast<uint8_t *>(
+ page_expand(self->buffer, self->buffer_size / self->get_page_size()));
+ self->buffer_size += self->get_page_size();
+ }
+
+ if (offset + size <= self->buffer_size) {
+ void *ptr = &self->buffer[offset];
+ self->prev_offset = offset;
+ self->curr_offset = offset + size;
+ return ptr;
+ }
+ return nullptr;
+}
+
+void *arena_expand(BaseAllocator *base, void *ptr, size_t alignment,
+ size_t size) {
+ ArenaAllocator *self = reinterpret_cast<ArenaAllocator *>(base);
+
+ if (self->buffer + self->prev_offset == ptr) {
+ self->curr_offset = self->prev_offset + size;
+ return ptr;
+ } else {
+ void *new_mem = arena_allocate(base, alignment, size);
+ memmove(new_mem, ptr, size);
+ return new_mem;
+ }
+ return nullptr;
+}
+
+bool arena_free(BaseAllocator *base, void *ptr) {
+ (void)base;
+ (void)ptr;
+ return true;
+}
+
+size_t ArenaAllocator::get_page_size() {
+ if (page_size == LIBC_PAGE_SIZE_SYSTEM) {
+ page_size = getpagesize();
+ }
+ return page_size;
+}
+
+static ArenaAllocator default_arena_allocator(LIBC_PAGE_SIZE,
+ 2 * sizeof(void *));
+BaseAllocator *block_allocator = &default_arena_allocator;
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/__support/alloc/arena.h b/libc/src/__support/alloc/arena.h
new file mode 100644
index 00000000000000..45b6915139e712
--- /dev/null
+++ b/libc/src/__support/alloc/arena.h
@@ -0,0 +1,47 @@
+//===-- An arena allocator using pages. -------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_ALLOC_ARENA_H
+#define LLVM_LIBC_SRC___SUPPORT_ALLOC_ARENA_H
+
+#include "hdr/types/size_t.h"
+#include "include/llvm-libc-macros/stdint-macros.h"
+#include "src/__support/alloc/base.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+void *arena_allocate(BaseAllocator *base, size_t alignment, size_t size);
+void *arena_expand(BaseAllocator *base, void *ptr, size_t alignment,
+ size_t size);
+bool arena_free(BaseAllocator *base, void *ptr);
+
+class ArenaAllocator : public BaseAllocator {
+public:
+ uint8_t *buffer;
+ size_t buffer_size;
+ size_t prev_offset;
+ size_t curr_offset;
+
+private:
+ size_t page_size;
+
+public:
+ constexpr ArenaAllocator(size_t page_size, size_t default_alignment)
+ : BaseAllocator(arena_allocate, arena_expand, arena_free,
+ default_alignment),
+ buffer(nullptr), buffer_size(0), prev_offset(0), curr_offset(0),
+ page_size(page_size) {}
+
+ size_t get_page_size();
+};
+
+extern BaseAllocator *arena_allocator;
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif
diff --git a/libc/src/__support/alloc/baremetal/CMakeLists.txt b/libc/src/__support/alloc/baremetal/CMakeLists.txt
new file mode 100644
index 00000000000000..845d2f5287bfbf
--- /dev/null
+++ b/libc/src/__support/alloc/baremetal/CMakeLists.txt
@@ -0,0 +1,13 @@
+add_object_library(
+ page
+ SRCS
+ page.cpp
+ HDRS
+ ../page.h
+ DEPENDS
+ libc.src.__support.alloc.base
+ libc.src.sys.mman.mmap
+ libc.src.sys.mman.mremap
+ libc.src.sys.mman.munmap
+ libc.src.unistd.getpagesize
+)
diff --git a/libc/src/__support/alloc/baremetal/page.cpp b/libc/src/__support/alloc/baremetal/page.cpp
new file mode 100644
index 00000000000000..4d92141bcc8276
--- /dev/null
+++ b/libc/src/__support/alloc/baremetal/page.cpp
@@ -0,0 +1,22 @@
+#include "src/__support/alloc/page.h"
+#include "src/__suport/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+extern "C" void *__llvm_libc_page_allocate(size_t n_pages);
+extern "C" void *__llvm_libc_page_expand(void *ptr, size_t n_pages);
+extern "C" bool __llvm_libc_page_free(void *ptr, size_t n_pages);
+
+void *page_allocate(size_t n_pages) {
+ return __llvm_libc_page_allocate(n_pages);
+}
+
+void *page_expand(void *ptr, size_t n_pages) {
+ return __llvm_libc_page_expand(ptr, n_pages);
+}
+
+bool page_free(void *ptr, size_t n_pages) {
+ return __llvm_libc_page_free(ptr, n_pages);
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/__support/alloc/base.cpp b/libc/src/__support/alloc/base.cpp
new file mode 100644
index 00000000000000..93684d457ee42d
--- /dev/null
+++ b/libc/src/__support/alloc/base.cpp
@@ -0,0 +1,16 @@
+#include "src/__support/alloc/base.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+void *BaseAllocator::alloc(size_t alignment, size_t size) {
+ return impl_alloc(this, alignment, size);
+}
+
+void *BaseAllocator::expand(void *ptr, size_t alignment, size_t size) {
+ return impl_expand(this, ptr, alignment, size);
+}
+
+bool BaseAllocator::free(void *ptr) { return impl_free(this, ptr); }
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/__support/alloc/base.h b/libc/src/__support/alloc/base.h
new file mode 100644
index 00000000000000..59370352953d3e
--- /dev/null
+++ b/libc/src/__support/alloc/base.h
@@ -0,0 +1,44 @@
+//===-- A generic base allocator. -------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_ALLOC_BASE_H
+#define LLVM_LIBC_SRC___SUPPORT_ALLOC_BASE_H
+
+#include "hdr/types/size_t.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+class BaseAllocator {
+public:
+ using AllocFunc = void *(BaseAllocator *self, size_t, size_t);
+ using ExpandFunc = void *(BaseAllocator *self, void *, size_t, size_t);
+ using FreeFunc = bool(BaseAllocator *self, void *);
+
+private:
+ // Implementation specific functions
+ AllocFunc *impl_alloc;
+ ExpandFunc *impl_expand;
+ FreeFunc *impl_free;
+
+public:
+ constexpr BaseAllocator(AllocFunc *ia, ExpandFunc *ie, FreeFunc *ifr,
+ size_t default_alignment)
+ : impl_alloc(ia), impl_expand(ie), impl_free(ifr),
+ default_alignment(default_alignment) {}
+
+ size_t default_alignment;
+
+ void *alloc(size_t alignment, size_t size);
+ void *expand(void *ptr, size_t alignment, size_t size);
+ bool free(void *ptr);
+};
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_ALLOC_BASE_H
diff --git a/libc/src/__support/alloc/linux/CMakeLists.txt b/libc/src/__support/alloc/linux/CMakeLists.txt
new file mode 100644
index 00000000000000..4484a5d60c9635
--- /dev/null
+++ b/libc/src/__support/alloc/linux/CMakeLists.txt
@@ -0,0 +1,16 @@
+add_object_library(
+ page
+ SRCS
+ page.cpp
+ HDRS
+ ../page.h
+ DEPENDS
+ libc.hdr.types.size_t
+ libc.include.llvm-libc-macros.stdlib_macros
+ libc.include.llvm-libc-macros.stdint_macros
+ libc.src.__support.alloc.base
+ libc.src.sys.mman.mmap
+ libc.src.sys.mman.mremap
+ libc.src.sys.mman.munmap
+ libc.src.unistd.getpagesize
+)
diff --git a/libc/src/__support/alloc/linux/page.cpp b/libc/src/__support/alloc/linux/page.cpp
new file mode 100644
index 00000000000000..1d9f04e951856e
--- /dev/null
+++ b/libc/src/__support/alloc/linux/page.cpp
@@ -0,0 +1,41 @@
+#include "src/__support/alloc/page.h"
+#include "include/llvm-libc-macros/stdint-macros.h"
+#include "include/llvm-libc-macros/stdlib-macros.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/memory_size.h"
+#include "src/sys/mman/mmap.h"
+#include "src/sys/mman/mremap.h"
+#include "src/sys/mman/munmap.h"
+#include "src/unistd/getpagesize.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+static void *alloc_hint = NULL;
+
+void *page_allocate(size_t n_pages) {
+ size_t page_size = getpagesize();
+ size_t size = n_pages * page_size;
+ size_t aligned_size = internal::SafeMemSize(size).align_up(page_size);
+
+ void *ptr = mmap(&alloc_hint, aligned_size, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ if (ptr == NULL)
+ return nullptr;
+
+ alloc_hint = (void *)(((uintptr_t)ptr) + aligned_size);
+ return ptr;
+}
+
+void *page_expand(void *ptr, size_t n_pages) {
+ (void)ptr;
+ (void)n_pages;
+ return nullptr;
+}
+
+bool page_free(void *ptr, size_t n_pages) {
+ (void)ptr;
+ (void)n_pages;
+ return false;
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/__support/alloc/page.h b/libc/src/__support/alloc/page.h
new file mode 100644
index 00000000000000..bb627b50cd6eb4
--- /dev/null
+++ b/libc/src/__support/alloc/page.h
@@ -0,0 +1,23 @@
+//===-- Page allocations ----------------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_ALLOC_PAGE_H
+#define LLVM_LIBC_SRC___SUPPORT_ALLOC_PAGE_H
+
+#include "hdr/types/size_t.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+void *page_allocate(size_t n_pages);
+void *page_expand(void *ptr, size_t n_pages);
+bool page_free(void *ptr, size_t n_pages);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_ALLOC_BASE_H
diff --git a/libc/src/__support/macros/CMakeLists.txt b/libc/src/__support/macros/CMakeLists.txt
index 99d4f640f283a4..5ef209f4f9c8f6 100644
--- a/libc/src/__support/macros/CMakeLists.txt
+++ b/libc/src/__support/macros/CMakeLists.txt
@@ -20,6 +20,12 @@ add_header_library(
libc.src.__support.macros.properties.compiler
)
+add_header_library(
+ page_size
+ HDRS
+ page_size.h
+)
+
add_header_library(
sanitizer
HDRS
diff --git a/libc/src/__support/macros/page_size.h b/libc/src/__support/macros/page_size.h
new file mode 100644
index 00000000000000..bc45dcc672d345
--- /dev/null
+++ b/libc/src/__support/macros/page_size.h
@@ -0,0 +1,17 @@
+//===-- Convenient page size macros -----------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_MACROS_PAGE_SIZE_H
+#define LLVM_LIBC_SRC___SUPPORT_MACROS_PAGE_SIZE_H
+
+#define LIBC_PAGE_SIZE_SYSTEM 0
+#define LIBC_PAGE_SIZE_4K (4 * 1024)
+#define LIBC_PAGE_SIZE_16K (16 * 1024)
+#define LIBC_PAGE_SIZE_64K (64 * 1024)
+
+#endif // LLVM_LIBC_SRC___SUPPORT_MACROS_PAGE_SIZE_H
diff --git a/libc/src/__support/memory_size.h b/libc/src/__support/memory_size.h
index cdd6a10222de10..a9df814be7156b 100644
--- a/libc/src/__support/memory_size.h
+++ b/libc/src/__suppo...
[truncated]
``````````
</details>
https://github.com/llvm/llvm-project/pull/121173
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