[libc] add mremap #112804

SoftJing1 · 2024-10-18T00:53:54Z

No description provided.

github-actions · 2024-10-18T00:54:12Z

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llvmbot · 2024-10-18T00:54:45Z

@llvm/pr-subscribers-libc

Author: Jingyu Qiu (SoftJing1)

Changes

Full diff: https://github.com/llvm/llvm-project/pull/112804.diff

8 Files Affected:

(modified) libc/newhdrgen/yaml/sys/mman.yaml (+11)
(modified) libc/spec/linux.td (+11)
(modified) libc/src/sys/mman/CMakeLists.txt (+7)
(modified) libc/src/sys/mman/linux/CMakeLists.txt (+13)
(added) libc/src/sys/mman/linux/mremap.cpp (+53)
(added) libc/src/sys/mman/mremap.h (+23)
(modified) libc/test/src/sys/mman/linux/CMakeLists.txt (+15)
(added) libc/test/src/sys/mman/linux/mremap_test.cpp (+67)

diff --git a/libc/newhdrgen/yaml/sys/mman.yaml b/libc/newhdrgen/yaml/sys/mman.yaml
index 272e7e2af16aaf..23637f733a2b8d 100644
--- a/libc/newhdrgen/yaml/sys/mman.yaml
+++ b/libc/newhdrgen/yaml/sys/mman.yaml
@@ -55,6 +55,17 @@ functions:
       - type: int
       - type: int
       - type: off_t
+  - name: mremap
+    standards:
+      - POSIX
+    return_type: void *
+    arguments:
+      - type: void *
+      - type: size_t
+      - type: size_t
+      - type: int
+      - type: void *
+        description: "This argument is optional."
   - name: mprotect
     standards:
       - POSIX
diff --git a/libc/spec/linux.td b/libc/spec/linux.td
index 395c2a6fe853a7..3b4fff383472ec 100644
--- a/libc/spec/linux.td
+++ b/libc/spec/linux.td
@@ -103,6 +103,17 @@ def Linux : StandardSpec<"Linux"> {
             ArgSpec<UnsignedIntType>,
           ]
         >,
+        FunctionSpec<
+          "mremap",
+          RetValSpec<VoidPtr>,
+          [
+            ArgSpec<VoidPtr>,
+            ArgSpec<SizeTType>,
+            ArgSpec<SizeTType>,
+            ArgSpec<IntType>,
+            ArgSpec<VoidPtr>,
+          ]
+        >,
       ]  // Functions
   >;
 
diff --git a/libc/src/sys/mman/CMakeLists.txt b/libc/src/sys/mman/CMakeLists.txt
index 9c74202a09f035..246460bab7a824 100644
--- a/libc/src/sys/mman/CMakeLists.txt
+++ b/libc/src/sys/mman/CMakeLists.txt
@@ -99,3 +99,10 @@ add_entrypoint_object(
   DEPENDS
     .${LIBC_TARGET_OS}.shm_unlink
 )
+
+add_entrypoint_object(
+  mremap,
+  ALIAS,
+  DEPENDS
+    .${LIBC_TARGET_OS}.mremap
+)
diff --git a/libc/src/sys/mman/linux/CMakeLists.txt b/libc/src/sys/mman/linux/CMakeLists.txt
index 00f4f0e64ec06b..740316b763dfa1 100644
--- a/libc/src/sys/mman/linux/CMakeLists.txt
+++ b/libc/src/sys/mman/linux/CMakeLists.txt
@@ -24,6 +24,19 @@ add_entrypoint_object(
     libc.src.errno.errno
 )
 
+add_entrypoint_object(
+  mremap
+  SRCS
+    mremap.cpp
+  HDRS
+    ../mremap.h
+  DEPENDS
+    libc.include.sys_mman
+    libc.include.sys_syscall
+    libc.src.__support.OSUtil.osutil
+    libc.src.errno.errno
+)
+
 add_entrypoint_object(
   munmap
   SRCS
diff --git a/libc/src/sys/mman/linux/mremap.cpp b/libc/src/sys/mman/linux/mremap.cpp
new file mode 100644
index 00000000000000..182d1c24829358
--- /dev/null
+++ b/libc/src/sys/mman/linux/mremap.cpp
@@ -0,0 +1,53 @@
+//===---------- Linux implementation of the POSIX mremap function
+//-----------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/sys/mman/mremap.h"
+
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/common.h"
+
+#include "src/__support/macros/config.h"
+#include "src/errno/libc_errno.h"
+#include <linux/param.h> // For EXEC_PAGESIZE.
+#include <stdarg.h>
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(void *, mremap,
+                   (void *old_address, size_t old_size, size_t new_size,
+                    int flags, ... /* void *new_address */)) {
+
+#ifdef SYS_mremap
+  long syscall_number = SYS_mremap;
+#else
+#error "mremap syscalls not available."
+#endif
+  long ret = 0;
+  if (flags & MREMAP_FIXED) {
+    void *arg;
+    va_list varargs;
+    va_start(varargs, flags);
+    arg = va_arg(varargs, void *);
+    va_end(varargs);
+    ret = LIBC_NAMESPACE::syscall_impl(syscall_number, old_address, old_size,
+                                       new_size, flags, arg);
+  } else {
+    ret = LIBC_NAMESPACE::syscall_impl(syscall_number, old_address, old_size,
+                                       new_size, flags);
+  }
+  if (ret < 0 && ret > -EXEC_PAGESIZE) {
+    libc_errno = static_cast<int>(-ret);
+    return MAP_FAILED;
+  }
+
+  return reinterpret_cast<void *>(ret);
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/sys/mman/mremap.h b/libc/src/sys/mman/mremap.h
new file mode 100644
index 00000000000000..5287658089dd54
--- /dev/null
+++ b/libc/src/sys/mman/mremap.h
@@ -0,0 +1,23 @@
+//===-- Implementation header for mremap function -----------------*- 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_SYS_MMAN_MREMAP_H
+#define LLVM_LIBC_SRC_SYS_MMAN_MREMAP_H
+
+#include "src/__support/macros/config.h"
+#include <sys/mman.h> // For size_t and off_t
+
+namespace LIBC_NAMESPACE_DECL {
+
+void *mremap(void *old_address, size_t old_size, size_t new_size, int flags,
+             ... /* void *new_address */);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_SYS_MMAN_MREMAP_H
diff --git a/libc/test/src/sys/mman/linux/CMakeLists.txt b/libc/test/src/sys/mman/linux/CMakeLists.txt
index b63c76f4306fac..dcc2045250a4c9 100644
--- a/libc/test/src/sys/mman/linux/CMakeLists.txt
+++ b/libc/test/src/sys/mman/linux/CMakeLists.txt
@@ -14,6 +14,21 @@ add_libc_unittest(
     libc.test.UnitTest.ErrnoSetterMatcher
 )
 
+add_libc_unittest(
+  mremap_test
+  SUITE
+    libc_sys_mman_unittests
+  SRCS
+    mremap_test.cpp
+  DEPENDS
+    libc.include.sys_mman
+    libc.src.errno.errno
+    libc.src.sys.mman.mmap
+    libc.src.sys.mman.mremap
+    libc.src.sys.mman.munmap
+    libc.test.UnitTest.ErrnoSetterMatcher
+)
+
 if (NOT LLVM_USE_SANITIZER)
   add_libc_unittest(
     mprotect_test
diff --git a/libc/test/src/sys/mman/linux/mremap_test.cpp b/libc/test/src/sys/mman/linux/mremap_test.cpp
new file mode 100644
index 00000000000000..36f606386467db
--- /dev/null
+++ b/libc/test/src/sys/mman/linux/mremap_test.cpp
@@ -0,0 +1,67 @@
+//===-- Unittests for mremap ----------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/errno/libc_errno.h"
+#include "src/sys/mman/mmap.h"
+#include "src/sys/mman/munmap.h"
+#include "test/UnitTest/ErrnoSetterMatcher.h"
+#include "test/UnitTest/Test.h"
+
+#include <sys/mman.h>
+
+using LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Fails;
+using LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Succeeds;
+
+TEST(LlvmLibcMremapTest, NoError) {
+  size_t initial_size = 128;
+  size_t new_size = 256;
+  LIBC_NAMESPACE::libc_errno = 0;
+
+  // Allocate memory using mmap.
+  void *addr =
+      LIBC_NAMESPACE::mmap(nullptr, initial_size, PROT_READ | PROT_WRITE,
+                           MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+  ASSERT_ERRNO_SUCCESS();
+  EXPECT_NE(addr, MAP_FAILED);
+
+  int *array = reinterpret_cast<int *>(addr);
+  // Writing to the memory should not crash the test.
+  array[0] = 123;
+  EXPECT_EQ(array[0], 123);
+
+  // Re-map the memory using mremap with an increased size.
+  void *new_addr =
+      LIBC_NAMESPACE::mremap(addr, initial_size, new_size, MREMAP_MAYMOVE);
+  ASSERT_ERRNO_SUCCESS();
+  EXPECT_NE(new_addr, MAP_FAILED);
+  EXPECT_EQ(reinterpret_cast<int *>(new_addr)[0],
+            123); // Verify data is preserved.
+
+  // Clean up memory by unmapping it.
+  EXPECT_THAT(LIBC_NAMESPACE::munmap(new_addr, new_size), Succeeds());
+}
+
+TEST(LlvmLibcMremapTest, Error_InvalidSize) {
+  size_t initial_size = 128;
+  LIBC_NAMESPACE::libc_errno = 0;
+
+  // Allocate memory using mmap.
+  void *addr =
+      LIBC_NAMESPACE::mmap(nullptr, initial_size, PROT_READ | PROT_WRITE,
+                           MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+  ASSERT_ERRNO_SUCCESS();
+  EXPECT_NE(addr, MAP_FAILED);
+
+  // Attempt to re-map the memory with an invalid new size (0).
+  void *new_addr =
+      LIBC_NAMESPACE::mremap(addr, initial_size, 0, MREMAP_MAYMOVE);
+  EXPECT_THAT(new_addr, Fails(EINVAL, MAP_FAILED));
+
+  // Clean up the original mapping.
+  EXPECT_THAT(LIBC_NAMESPACE::munmap(addr, initial_size), Succeeds());
+}

SoftJing1 · 2024-10-18T01:13:35Z

@SchrodingerZhu @michaelrj-google PTAL, thanks

SchrodingerZhu

Thanks for contributing to libc! This PR looks like a great start point. I quickly scanned the code and spot some formatting issues. Could you please correct them? Thank you!

I will look deeper into the code and logic later.

libc/src/sys/mman/linux/mremap.cpp

libc/src/sys/mman/mremap.h

michaelrj-google

This looks like a good start, but you need to add mremap to entrypoints.txt for it to actually build

libc/src/sys/mman/linux/mremap.cpp

SchrodingerZhu

LGTM.

libc/src/sys/mman/linux/mremap.cpp

michaelrj-google

Looks good to me, would you like me to merge this for you?

SoftJing1 · 2024-11-05T21:14:04Z

Looks good to me, would you like me to merge this for you?

Yes please, thanks.

michaelrj-google

I noticed one last thing during my final review. I will merge it after this is fixed.

libc/newhdrgen/yaml/sys/mman.yaml

libc/spec/linux.td

SoftJing1 · 2024-11-05T21:50:19Z

fixed

github-actions · 2024-11-06T18:26:10Z

@SoftJing1 Congratulations on having your first Pull Request (PR) merged into the LLVM Project!

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llvmbot added the libc label Oct 18, 2024

add mremap

525ae42

SoftJing1 force-pushed the main branch from 7d22fba to 525ae42 Compare October 18, 2024 01:11

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add entry point of test

9f34176

SchrodingerZhu approved these changes Oct 31, 2024

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format

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jhuber6 changed the title ~~add mremap~~ [libc] add mremap Nov 5, 2024

fix type spec

4eb09f0

michaelrj-google merged commit 5a6cc50 into llvm:main Nov 6, 2024
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[libc] add mremap #112804

[libc] add mremap #112804

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