llvm · Il-Capitano · May 19, 2025 · May 20, 2025 · May 21, 2025 · Jun 11, 2025
diff --git a/compiler-rt/CMakeLists.txt b/compiler-rt/CMakeLists.txt
@@ -603,6 +603,10 @@ string(REGEX REPLACE "-stdlib=[a-zA-Z+]*" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}
 list(APPEND COMPILER_RT_COMMON_CFLAGS ${stdlib_flag})
 list(APPEND COMPILER_RT_COMMON_LINK_FLAGS ${stdlib_flag})
 
+# Add assembler flags for execute-only code generation. C and C++ flags should have already
+# been added to CMAKE_C_FLAGS and CMAKE_CXX_FLAGS.
+append_string_if(LLVM_EXECUTE_ONLY_CODE -DCOMPILER_RT_EXECUTE_ONLY_CODE CMAKE_ASM_FLAGS)
+
 # TODO: There's a lot of duplication across lib/*/tests/CMakeLists.txt files,
 # move some of the common flags to COMPILER_RT_UNITTEST_CFLAGS.
 

diff --git a/compiler-rt/lib/builtins/assembly.h b/compiler-rt/lib/builtins/assembly.h
@@ -71,9 +71,24 @@
 
 #endif
 
+#if defined(__aarch64__) && defined(__ELF__) &&                                \
+    defined(COMPILER_RT_EXECUTE_ONLY_CODE)
+// The assembler always creates an implicit '.text' section with default flags
+// (SHF_ALLOC | SHF_EXECINSTR), which is incompatible with the execute-only
+// '.text' section we want to create here because of the missing
+// SHF_AARCH64_PURECODE section flag. To solve this, we use 'unique,0' to
+// differentiate the two sections. The output will therefore have two separate
+// sections named '.text', where code will be placed into the execute-only
+// '.text' section, and the implicitly-created one will be empty.
+#define TEXT_SECTION                                                           \
+  .section .text,"axy",@progbits,unique,0
+#else
+#define TEXT_SECTION                                                           \
+  .text
+#endif
+
 #if defined(__arm__) || defined(__aarch64__) || defined(__arm64ec__)
 #define FUNC_ALIGN                                                             \
-  .text SEPARATOR                                                              \
   .balign 16 SEPARATOR
 #else
 #define FUNC_ALIGN
@@ -230,6 +245,7 @@
 #endif
 
 #define DEFINE_COMPILERRT_FUNCTION(name)                                       \
+  TEXT_SECTION SEPARATOR                                                       \
   DEFINE_CODE_STATE                                                            \
   FILE_LEVEL_DIRECTIVE SEPARATOR                                               \
   .globl FUNC_SYMBOL(SYMBOL_NAME(name)) SEPARATOR                              \
@@ -239,6 +255,7 @@
   FUNC_SYMBOL(SYMBOL_NAME(name)):
 
 #define DEFINE_COMPILERRT_THUMB_FUNCTION(name)                                 \
+  TEXT_SECTION SEPARATOR                                                       \
   DEFINE_CODE_STATE                                                            \
   FILE_LEVEL_DIRECTIVE SEPARATOR                                               \
   .globl FUNC_SYMBOL(SYMBOL_NAME(name)) SEPARATOR                              \
@@ -248,6 +265,7 @@
   FUNC_SYMBOL(SYMBOL_NAME(name)):
 
 #define DEFINE_COMPILERRT_PRIVATE_FUNCTION(name)                               \
+  TEXT_SECTION SEPARATOR                                                       \
   DEFINE_CODE_STATE                                                            \
   FILE_LEVEL_DIRECTIVE SEPARATOR                                               \
   .globl FUNC_SYMBOL(SYMBOL_NAME(name)) SEPARATOR                              \
@@ -257,6 +275,7 @@
   FUNC_SYMBOL(SYMBOL_NAME(name)):
 
 #define DEFINE_COMPILERRT_PRIVATE_FUNCTION_UNMANGLED(name)                     \
+  TEXT_SECTION SEPARATOR                                                       \
   DEFINE_CODE_STATE                                                            \
   .globl FUNC_SYMBOL(name) SEPARATOR                                           \
   SYMBOL_IS_FUNC(name) SEPARATOR                                               \
@@ -265,6 +284,7 @@
   FUNC_SYMBOL(name):
 
 #define DEFINE_COMPILERRT_OUTLINE_FUNCTION_UNMANGLED(name)                     \
+  TEXT_SECTION SEPARATOR                                                       \
   DEFINE_CODE_STATE                                                            \
   FUNC_ALIGN                                                                   \
   .globl FUNC_SYMBOL(name) SEPARATOR                                           \

diff --git a/compiler-rt/lib/fuzzer/CMakeLists.txt b/compiler-rt/lib/fuzzer/CMakeLists.txt
@@ -162,6 +162,7 @@ if(OS_NAME MATCHES "Android|Linux|Fuchsia" AND
       CFLAGS ${TARGET_CFLAGS}
       CMAKE_ARGS -DCMAKE_CXX_COMPILER_WORKS=ON
                  -DCMAKE_POSITION_INDEPENDENT_CODE=ON
+                 -DLLVM_EXECUTE_ONLY_CODE=${LLVM_EXECUTE_ONLY_CODE}
                  -DLIBCXXABI_ENABLE_EXCEPTIONS=OFF
                  -DLIBCXX_ABI_NAMESPACE=__Fuzzer
                  -DLIBCXX_ENABLE_EXCEPTIONS=OFF)

diff --git a/compiler-rt/lib/hwasan/hwasan_setjmp_aarch64.S b/compiler-rt/lib/hwasan/hwasan_setjmp_aarch64.S
@@ -28,7 +28,7 @@
 // stack pointer when compiling a C function.
 // Hence we have to write this function in assembly.
 
-.section .text
+TEXT_SECTION
 .file "hwasan_setjmp_aarch64.S"
 
 .global ASM_WRAPPER_NAME(setjmp)

diff --git a/compiler-rt/lib/hwasan/hwasan_tag_mismatch_aarch64.S b/compiler-rt/lib/hwasan/hwasan_tag_mismatch_aarch64.S
@@ -70,7 +70,7 @@
 // clobbering the x17 register in error reports, and that the program will have
 // a runtime dependency on the __hwasan_tag_mismatch_v2 symbol therefore it will
 // fail to start up given an older (i.e. incompatible) runtime.
-.section .text
+TEXT_SECTION
 .file "hwasan_tag_mismatch_aarch64.S"
 .global __hwasan_tag_mismatch
 .type __hwasan_tag_mismatch, %function

diff --git a/compiler-rt/lib/msan/tests/CMakeLists.txt b/compiler-rt/lib/msan/tests/CMakeLists.txt
@@ -139,6 +139,7 @@ if(COMPILER_RT_CAN_EXECUTE_TESTS AND
     add_custom_libcxx(libcxx_msan_${arch} ${LIBCXX_PREFIX}
       DEPS ${MSAN_RUNTIME_LIBRARIES}
       CFLAGS ${MSAN_LIBCXX_CFLAGS} ${TARGET_CFLAGS}
+      CMAKE_ARGS -DLLVM_EXECUTE_ONLY_CODE=${LLVM_EXECUTE_ONLY_CODE}
       USE_TOOLCHAIN)
     set(MSAN_LIBCXX_DIR ${LIBCXX_PREFIX}/lib/)
 

diff --git a/compiler-rt/lib/orc/elfnix_tls.aarch64.S b/compiler-rt/lib/orc/elfnix_tls.aarch64.S
@@ -13,9 +13,11 @@
 // The content of this file is aarch64-only
 #if defined(__arm64__) || defined(__aarch64__)
 
+#include "builtins/assembly.h"
+
 #define REGISTER_SAVE_SPACE_SIZE     32 * 24
 
-        .text
+        TEXT_SECTION
 
   // returns address of TLV in x0, all other registers preserved
   // TODO: add fast-path for repeat access

diff --git a/compiler-rt/lib/orc/sysv_reenter.arm64.S b/compiler-rt/lib/orc/sysv_reenter.arm64.S
@@ -13,7 +13,9 @@
 // The content of this file is arm64-only
 #if defined(__arm64__) || defined(__aarch64__)
 
-        .text
+#include "builtins/assembly.h"
+
+        TEXT_SECTION
 
         // Saves GPRs, calls __orc_rt_resolve
         .globl __orc_rt_sysv_reenter

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors_vfork_aarch64.inc.S b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors_vfork_aarch64.inc.S
@@ -5,6 +5,7 @@
 
 ASM_HIDDEN(COMMON_INTERCEPTOR_SPILL_AREA)
 
+TEXT_SECTION
 .comm _ZN14__interception10real_vforkE,8,8
 .globl ASM_WRAPPER_NAME(vfork)
 ASM_TYPE_FUNCTION(ASM_WRAPPER_NAME(vfork))

diff --git a/compiler-rt/lib/tsan/CMakeLists.txt b/compiler-rt/lib/tsan/CMakeLists.txt
@@ -30,6 +30,7 @@ if(COMPILER_RT_LIBCXX_PATH AND
     add_custom_libcxx(libcxx_tsan_${arch} ${LIBCXX_PREFIX}
       DEPS ${TSAN_RUNTIME_LIBRARIES}
       CFLAGS ${TARGET_CFLAGS} -fsanitize=thread
+      CMAKE_ARGS -DLLVM_EXECUTE_ONLY_CODE=${LLVM_EXECUTE_ONLY_CODE}
       USE_TOOLCHAIN)
     list(APPEND libcxx_tsan_deps libcxx_tsan_${arch}-install-cmake326-workaround)
   endforeach()

diff --git a/compiler-rt/lib/tsan/rtl/tsan_rtl_aarch64.S b/compiler-rt/lib/tsan/rtl/tsan_rtl_aarch64.S
@@ -4,10 +4,8 @@
 #include "sanitizer_common/sanitizer_asm.h"
 #include "builtins/assembly.h"
 
-#if !defined(__APPLE__)
-.section .text
-#else
-.section __TEXT,__text
+TEXT_SECTION
+#if defined(__APPLE__)
 .align 3
 #endif
 

diff --git a/compiler-rt/lib/xray/xray_trampoline_AArch64.S b/compiler-rt/lib/xray/xray_trampoline_AArch64.S
@@ -37,7 +37,7 @@
 #endif
 .endm
 
-.text
+TEXT_SECTION
 .p2align 2
 .global ASM_SYMBOL(__xray_FunctionEntry)
 ASM_HIDDEN(__xray_FunctionEntry)