[libc] [llvm] [libc] enable stack protectors and frame pointers on default (PR #86288)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libc

Author: Schrodinger ZHU Yifan (SchrodingerZhu)

<details>
<summary>Changes</summary>

OS distros tend to enable them by default:

- https://fedoraproject.org/wiki/Changes/fno-omit-frame-pointer
- https://wiki.archlinux.org/title/Arch_package_guidelines/Security
- https://gitlab.archlinux.org/archlinux/packaging/packages/clang/-/blob/main/enable-fstack-protector-strong-by-default.patch?ref_type=heads

---
Full diff: https://github.com/llvm/llvm-project/pull/86288.diff


3 Files Affected:

- (modified) libc/CMakeLists.txt (+4) 
- (modified) libc/cmake/modules/LLVMLibCCompileOptionRules.cmake (+9) 
- (modified) utils/bazel/llvm-project-overlay/libc/libc_build_rules.bzl (+8-1) 


``````````diff
diff --git a/libc/CMakeLists.txt b/libc/CMakeLists.txt
index a0d79858a896ad..0c1fdae04cf955 100644
--- a/libc/CMakeLists.txt
+++ b/libc/CMakeLists.txt
@@ -47,6 +47,10 @@ set(LIBC_NAMESPACE ${default_namespace}
   CACHE STRING "The namespace to use to enclose internal implementations. Must start with '__llvm_libc'."
 )
 
+# Codegen options.
+option(LLVM_LIBC_KEEP_FRAME_POINTER "Keep frame pointers in LLVM libc" ON)
+option(LLVM_LIBC_ENABLE_STACK_PROTECTOR "Enable stack protector for LLVM libc" ON)
+
 if(LLVM_LIBC_FULL_BUILD OR LLVM_LIBC_GPU_BUILD)
   if(NOT LIBC_HDRGEN_EXE)
     # We need to set up hdrgen first since other targets depend on it.
diff --git a/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake b/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
index 5bc0898298ce39..df7311f8ec6d9d 100644
--- a/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
+++ b/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
@@ -60,6 +60,15 @@ function(_get_common_compile_options output_var flags)
     if (LIBC_CC_SUPPORTS_PATTERN_INIT)
       list(APPEND compile_options "-ftrivial-auto-var-init=pattern")
     endif()
+    if (LLVM_LIBC_KEEP_FRAME_POINTER)
+      list(APPEND compile_options "-fno-omit-frame-pointer")
+      if (LIBC_TARGET_ARCHITECTURE_IS_X86)
+        list(APPEND compile_options "-mno-omit-leaf-frame-pointer")
+      endif()
+    endif()
+    if (LLVM_LIBC_ENABLE_STACK_PROTECTOR)
+      list(APPEND compile_options "-fstack-protector-strong")
+    endif()
     list(APPEND compile_options "-Wall")
     list(APPEND compile_options "-Wextra")
     # -DLIBC_WNO_ERROR=ON if you can't build cleanly with -Werror.
diff --git a/utils/bazel/llvm-project-overlay/libc/libc_build_rules.bzl b/utils/bazel/llvm-project-overlay/libc/libc_build_rules.bzl
index 7d815bc4a2299c..7dc12bade2605a 100644
--- a/utils/bazel/llvm-project-overlay/libc/libc_build_rules.bzl
+++ b/utils/bazel/llvm-project-overlay/libc/libc_build_rules.bzl
@@ -78,7 +78,6 @@ def libc_function(
                      its deps.
       **kwargs: Other attributes relevant for a cc_library. For example, deps.
     """
-
     # We use the explicit equals pattern here because append and += mutate the
     # original list, where this creates a new list and stores it in deps.
     copts = copts or []
@@ -87,7 +86,15 @@ def libc_function(
         "-fno-builtin",
         "-fno-lax-vector-conversions",
         "-ftrivial-auto-var-init=pattern",
+        "-fno-omit-frame-pointer",
+        "-fstack-protector-strong",
     ]
+    # x86 targets have -mno-omit-leaf-frame-pointer.
+    platform_copts = selects.with_or({
+        PLATFORM_CPU_X86_64: ["-mno-omit-leaf-frame-pointer"],
+        "//conditions:default": []
+    })
+    copts = copts + platform_copts
 
     # We compile the code twice, the first target is suffixed with ".__internal__" and contains the
     # C++ functions in the "LIBC_NAMESPACE" namespace. This allows us to test the function in the

``````````

</details>


https://github.com/llvm/llvm-project/pull/86288