fix: build on ARM32 targets

CHANGELOG.md

@@ -15,6 +15,7 @@
 - Native: clean up stale envelopes after crashes with `SENTRY_TRANSPORT=none`. ([#2049](https://github.com/getsentry/sentry-native/pull/2049))
 - `sentry_set_trace` omits `parent_span_id` when the caller does not provide one, instead of serializing it as `null`. ([#2047](https://github.com/getsentry/sentry-native/pull/2047))
 - Native/Linux i386: write valid thread stack descriptors to minidumps when stack addresses use the upper half of the 32-bit address space. ([#2054](https://github.com/getsentry/sentry-native/pull/2054))
+- Linux/ARM32: fix builds on 32-bit ARM systems, including 32-bit Raspberry Pi OS installations running a 64-bit kernel. ([#2063](https://github.com/getsentry/sentry-native/pull/2063))
 - Guard size arithmetic when parsing envelopes and Linux OS release data, copying slices, and allocating memory during crash handling. ([#2059](https://github.com/getsentry/sentry-native/pull/2059))
 
 **Thank you**:

CMakeLists.txt

@@ -661,6 +661,11 @@ if(ANDROID)
 	set(_SENTRY_PLATFORM_LIBS "dl" "log")
 elseif(LINUX)
 	set(_SENTRY_PLATFORM_LIBS "dl" "rt")
+	sentry_find_atomic_library(_SENTRY_ATOMIC_LIBRARY)
+	if(_SENTRY_ATOMIC_LIBRARY)
+		list(APPEND _SENTRY_PLATFORM_LIBS "${_SENTRY_ATOMIC_LIBRARY}")
+	endif()
+	unset(_SENTRY_ATOMIC_LIBRARY)
 elseif(WIN32)
 	if (XBOX)
 		set(_SENTRY_PLATFORM_LIBS "version")

cmake/utils.cmake

@@ -22,3 +22,28 @@ function(sentry_get_property NAME)
 	endif()
 	set("SENTRY_${NAME}" "${prop}" PARENT_SCOPE)
 endfunction()
+
+function(sentry_find_atomic_library OUT_VAR)
+	include(CheckCSourceCompiles)
+	include(CMakePushCheckState)
+	cmake_push_check_state(RESET)
+	set(ATOMIC_U64_SOURCE "
+		#include <stdint.h>
+		uint64_t value;
+		int main(void) {
+			return (int)__atomic_load_n(&value, __ATOMIC_SEQ_CST);
+		}")
+	check_c_source_compiles("${ATOMIC_U64_SOURCE}" SENTRY_HAVE_ATOMIC_U64)
+	if(SENTRY_HAVE_ATOMIC_U64)
+		set(ATOMIC_LIBRARY)
+	else()
+		set(CMAKE_REQUIRED_LIBRARIES atomic)
+		check_c_source_compiles("${ATOMIC_U64_SOURCE}" SENTRY_HAVE_ATOMIC_U64_WITH_LIB)
+		if(NOT SENTRY_HAVE_ATOMIC_U64_WITH_LIB)
+			message(FATAL_ERROR "64-bit atomic operations are not supported")
+		endif()
+		set(ATOMIC_LIBRARY atomic)
+	endif()
+	cmake_pop_check_state()
+	set(${OUT_VAR} "${ATOMIC_LIBRARY}" PARENT_SCOPE)
+endfunction()

src/modulefinder/sentry_modulefinder_linux.c

@@ -506,7 +506,7 @@ sentry__procmaps_module_to_value(const sentry_module_t *module)
         mmapped_module.is_mmapped = true;
         mmapped_module.num_mappings = 1;
         mmapped_module.mappings[0].addr
-            = (uint64_t)mm.ptr + module->offset_in_inode;
+            = (uint64_t)(uintptr_t)mm.ptr + module->offset_in_inode;
         mmapped_module.mappings[0].size = mm.len - module->offset_in_inode;
 
         sentry__procmaps_read_ids_from_elf(mod_val, &mmapped_module);

src/sentry_cpu_relax.h

@@ -13,8 +13,10 @@
 #else
 #    if defined(__i386__) || defined(__x86_64__) || defined(__amd64__)
 #        define sentry__cpu_relax() __asm__ __volatile__("pause")
-#    elif defined(__aarch64__) || defined(__arm__)
+#    elif defined(__aarch64__)
 #        define sentry__cpu_relax() __asm__ __volatile__("yield")
+#    elif defined(__arm__)
+#        define sentry__cpu_relax() __asm__ __volatile__("nop")
 #    elif defined(__powerpc__) || defined(__ppc__) || defined(__PPC__)
 #        define sentry__cpu_relax() __asm__ __volatile__("or 27,27,27")
 #    elif defined(__riscv)

tests/unit/test_modulefinder.c

@@ -203,16 +203,17 @@ parse_elf_and_check_code_and_build_id(const char *rel_elf_path,
 
     sentry_module_t module = { 0 };
     module.num_mappings = 1;
-    size_t *file_size = &module.mappings[0].size;
-    char **buf = (char **)&module.mappings[0].addr;
 
     sentry_value_t value = sentry_value_new_object();
     sentry_path_t *elf_path = sentry__path_join_str(dir, rel_elf_path);
-    *buf = sentry__path_read_to_buffer(elf_path, file_size);
+    size_t file_size = 0;
+    char *buf = sentry__path_read_to_buffer(elf_path, &file_size);
     sentry__path_free(elf_path);
+    module.mappings[0].addr = (uint64_t)(uintptr_t)buf;
+    module.mappings[0].size = file_size;
 
     TEST_CHECK(sentry__procmaps_read_ids_from_elf(value, &module));
-    sentry_free(*buf);
+    sentry_free(buf);
     sentry__path_free(dir);
 
     if (expected_code_id) {

vendor/libunwind/CMakeLists.txt

@@ -16,22 +16,27 @@ set(LIBUNWIND_SRC "${CMAKE_CURRENT_SOURCE_DIR}/src")
 set(LIBUNWIND_INC "${CMAKE_CURRENT_SOURCE_DIR}/include")
 
 # Detect architecture
-if(CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64|AMD64|amd64")
-    set(UNWIND_ARCH "x86_64")
-    set(UNWIND_ELF "elf64")
-elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "aarch64|ARM64|arm64")
-    set(UNWIND_ARCH "aarch64")
-    set(UNWIND_ELF "elf64")
-elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "i[3-6]86|x86")
-    set(UNWIND_ARCH "x86")
-    set(UNWIND_ELF "elf32")
-elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "^(arm|ARM)")
-    set(UNWIND_ARCH "arm")
-    set(UNWIND_ELF "elf32")
+string(TOLOWER "${CMAKE_SYSTEM_PROCESSOR}" _UNWIND_PROCESSOR)
+if(_UNWIND_PROCESSOR MATCHES "^(x86_64|amd64|x64|i[3-6]86|x86)$")
+    set(_UNWIND_ARCH_32 "x86")
+    set(_UNWIND_ARCH_64 "x86_64")
+elseif(_UNWIND_PROCESSOR MATCHES "^(aarch64|arm64|arm)")
+    set(_UNWIND_ARCH_32 "arm")
+    set(_UNWIND_ARCH_64 "aarch64")
 else()
     message(FATAL_ERROR "Unsupported architecture for vendored libunwind: ${CMAKE_SYSTEM_PROCESSOR}")
 endif()
 
+if(CMAKE_SIZEOF_VOID_P EQUAL 4)
+    set(UNWIND_ARCH "${_UNWIND_ARCH_32}")
+    set(UNWIND_ELF "elf32")
+elseif(CMAKE_SIZEOF_VOID_P EQUAL 8)
+    set(UNWIND_ARCH "${_UNWIND_ARCH_64}")
+    set(UNWIND_ELF "elf64")
+else()
+    message(FATAL_ERROR "Unsupported pointer size for vendored libunwind: ${CMAKE_SIZEOF_VOID_P}")
+endif()
+
 # Common sources (libunwind_la_SOURCES_common + os sources for Linux)
 set(UNWIND_COMMON_SOURCES
     ${LIBUNWIND_SRC}/os-linux.c