[libc] add mremap syscall wrapper

[SchrodingerZhu]

We need to create a mremap wrapper for linux targets, see https://man7.org/linux/man-pages/man2/mremap.2.html.

This requires:

• implement the entrypoint header similar to libc/src/sys/mman/mmap.h
  • modify libc/src/sys/mman/CMakeLists.txt accordingly
• implement the entrypoint similar to libc/src/sys/mman/linux/mmap.cpp
  • modify libc/src/sys/mman/linux/CMakeLists.txt accordingly
• add in the header spec
  • modify functions section in libc/newhdrgen/yaml/sys/mman.yaml
  • modify SysMMan section in libc/spec/linux.td
• add in test
  • similar to libc/test/src/sys/mman/linux/mmap_test.cpp
  • modify libc/test/src/sys/mman/linux/CMakeLists.txt accordingly

---

Misc:

• How to build libc for dev: https://libc.llvm.org/full_host_build.html
• Code style and dev guide: https://libc.llvm.org/dev/index.html

If you use vscode, sample settings are as the following (optional settings are useful in speeding up the compilation):

{
    "cmake.sourceDirectory": "${workspaceFolder}/runtimes",
    "cmake.configureSettings": {
        "CMAKE_EXPORT_COMPILE_COMMANDS": true,
        "LLVM_ENABLE_RUNTIMES": [
            "libc",
            "compiler-rt"
        ],
        "LLVM_LIBC_FULL_BUILD": true,
        "LLVM_USE_LINKER": "lld", // optional: requires installing lld
        "CMAKE_CXX_COMPILER_LAUNCHER": "sccache", // optional: requires installing sccache first
        "CMAKE_C_COMPILER_LAUNCHER": "sccache", // optional: requires installing sccache first
        "CMAKE_CXX_COMPILER": "/usr/bin/clang++",
        "CMAKE_C_COMPILER": "/usr/bin/clang",
        "LLVM_LIBC_INCLUDE_SCUDO": true,
        "COMPILER_RT_BUILD_SCUDO_STANDALONE_WITH_LLVM_LIBC": true,
        "COMPILER_RT_BUILD_GWP_ASAN": false,
        "COMPILER_RT_SCUDO_STANDALONE_BUILD_SHARED": false,
        "LIBC_USE_NEW_HEADER_GEN": true
    },
    "cmake.generator": "Ninja", // optional: requires installing Ninja
    "editor.formatOnSave": true,
    "files.insertFinalNewline": true,
    "clangd.arguments": [
        "--header-insertion=never"
    ]
}

[llvmbot]

Hi!

This issue may be a good introductory issue for people new to working on LLVM. If you would like to work on this issue, your first steps are:

1. Check that no other contributor has already been assigned to this issue. If you believe that no one is actually working on it despite an assignment, ping the person. After one week without a response, the assignee may be changed.
2. In the comments of this issue, request for it to be assigned to you, or just create a pull request after following the steps below. Mention this issue in the description of the pull request.
3. Fix the issue locally.
4. Run the test suite locally. Remember that the subdirectories under test/ create fine-grained testing targets, so you can e.g. use make check-clang-ast to only run Clang's AST tests.
5. Create a Git commit.
6. Run git clang-format HEAD~1 to format your changes.
7. Open a pull request to the upstream repository on GitHub. Detailed instructions can be found in GitHub's documentation. Mention this issue in the description of the pull request.

If you have any further questions about this issue, don't hesitate to ask via a comment in the thread below.

[llvmbot]

@llvm/issue-subscribers-good-first-issue

Author: Schrodinger ZHU Yifan (SchrodingerZhu)

We need to create a `mremap` wrapper for linux targets, see https://man7.org/linux/man-pages/man2/mremap.2.html.

This requires:

• implement the entrypoint header similar to libc/src/sys/mman/mmap.h
  • modify libc/src/sys/mman/CMakeLists.txt accordingly
• implement the entrypoint similar to libc/src/sys/mman/linux/mmap.cpp
  • modify libc/src/sys/mman/linux/CMakeLists.txt accordingly
• add in the header spec
  • modify functions section in libc/newhdrgen/yaml/sys/mman.yaml
  • modify SysMMan section in libc/spec/linux.td
• add in test
  • similar to libc/test/src/sys/mman/linux/mmap_test.cpp
  • modify libc/test/src/sys/mman/linux/CMakeLists.txt accordingly

---

Misc:

• How to build libc for dev: https://libc.llvm.org/full_host_build.html
• Code style and dev guide: https://libc.llvm.org/dev/index.html

[SchrodingerZhu]

@SoftJing1 wanted to have a try

[llvmbot]

@llvm/issue-subscribers-libc

Author: Schrodinger ZHU Yifan (SchrodingerZhu)

We need to create a `mremap` wrapper for linux targets, see https://man7.org/linux/man-pages/man2/mremap.2.html.

This requires:

• implement the entrypoint header similar to libc/src/sys/mman/mmap.h
  • modify libc/src/sys/mman/CMakeLists.txt accordingly
• implement the entrypoint similar to libc/src/sys/mman/linux/mmap.cpp
  • modify libc/src/sys/mman/linux/CMakeLists.txt accordingly
• add in the header spec
  • modify functions section in libc/newhdrgen/yaml/sys/mman.yaml
  • modify SysMMan section in libc/spec/linux.td
• add in test
  • similar to libc/test/src/sys/mman/linux/mmap_test.cpp
  • modify libc/test/src/sys/mman/linux/CMakeLists.txt accordingly

---

Misc:

• How to build libc for dev: https://libc.llvm.org/full_host_build.html
• Code style and dev guide: https://libc.llvm.org/dev/index.html

If you use vscode, sample settings are as the following (optional settings are useful in speeding up the compilation):

{
    "cmake.sourceDirectory": "${workspaceFolder}/runtimes",
    "cmake.configureSettings": {
        "CMAKE_EXPORT_COMPILE_COMMANDS": true,
        "LLVM_ENABLE_RUNTIMES": [
            "libc",
            "compiler-rt"
        ],
        "LLVM_LIBC_FULL_BUILD": true,
        "LLVM_USE_LINKER": "lld", // optional: requires installing lld
        "CMAKE_CXX_COMPILER_LAUNCHER": "sccache", // optional: requires installing sccache first
        "CMAKE_C_COMPILER_LAUNCHER": "sccache", // optional: requires installing sccache first
        "CMAKE_CXX_COMPILER": "/usr/bin/clang++",
        "CMAKE_C_COMPILER": "/usr/bin/clang",
        "LLVM_LIBC_INCLUDE_SCUDO": true,
        "COMPILER_RT_BUILD_SCUDO_STANDALONE_WITH_LLVM_LIBC": true,
        "COMPILER_RT_BUILD_GWP_ASAN": false,
        "COMPILER_RT_SCUDO_STANDALONE_BUILD_SHARED": false,
        "LIBC_USE_NEW_HEADER_GEN": true
    },
    "cmake.generator": "Ninja", // optional: requires installing Ninja
    "editor.formatOnSave": true,
    "files.insertFinalNewline": true,
    "clangd.arguments": [
        "--header-insertion=never"
    ]
}

[AlyElashram]

I can take a look at this if possible 👍

[SchrodingerZhu]

hi @AlyElashram, @SoftJing1 is currently looking into this. I will let you know if anything changed. That is being said, I have opened another issue for remap_file_pages if you want to have a try (#110122). It should be following largely the same instructions as above.

[WilliamFreedman]

Looks like nobody's currently assigned, I'd love to take a look at it if that's right.

[nickdesaulniers]

@WilliamFreedman we can't assign users who aren't members of the llvm github org. It sounds like @SoftJing1 is looking into this?

[SoftJing1]

@WilliamFreedman @nickdesaulniers Yes I am currently working on this, and hopefully will get it done this week.

[lntue]

@WilliamFreedman we can't assign users who aren't members of the llvm github org. It sounds like @SoftJing1 is looking into this?

On the side note, I think we can assign it if the users comment on the issue. Members of llvm github org will have commit rights to the repo.

[zenmov]

@SoftJing1 are you still working on this?

[SoftJing1]

@SoftJing1 are you still working on this?

Yes

[whiteio]

Hi @SoftJing1 are you still working on this? I'd like to do it if not

[SchrodingerZhu]

Ah, sorry. It is my fault.

The PR is already merged but I forget to close the issue.

@whiteio thanks for your interest in contributing to LLVM-libc. We do have a lot of other syscall wrappers or libc functions unimplemented but I currently do not have the time to create more good first issues. You are welcome to join the discord to ask whether there are other similar contribution opportunities.