Add testlibcxx config for esp32c3-devkit

Author: Barto22

boards/risc-v/esp32c3/esp32c3-devkit/configs/testlibcxx/defconfig

@@ -0,0 +1,58 @@
+#
+# This file is autogenerated: PLEASE DO NOT EDIT IT.
+#
+# You can use "make menuconfig" to make any modifications to the installed .config file.
+# You can then do "make savedefconfig" to generate a new defconfig file that includes your
+# modifications.
+#
+# CONFIG_NSH_ARGCAT is not set
+# CONFIG_NSH_CMDOPT_HEXDUMP is not set
+CONFIG_ARCH="risc-v"
+CONFIG_ARCH_BOARD="esp32c3-devkit"
+CONFIG_ARCH_BOARD_COMMON=y
+CONFIG_ARCH_BOARD_ESP32C3_DEVKIT=y
+CONFIG_ARCH_CHIP="esp32c3"
+CONFIG_ARCH_CHIP_ESP32C3=y
+CONFIG_ARCH_INTERRUPTSTACK=1536
+CONFIG_ARCH_RISCV=y
+CONFIG_ARCH_STACKDUMP=y
+CONFIG_BOARDCTL_RESET=y
+CONFIG_BOARD_LOOPSPERMSEC=15000
+CONFIG_BUILTIN=y
+CONFIG_DEFAULT_TASK_STACKSIZE=8192
+CONFIG_FS_PROCFS=y
+CONFIG_IDLETHREAD_STACKSIZE=2048
+CONFIG_INIT_ENTRYPOINT="nsh_main"
+CONFIG_INTELHEX_BINARY=y
+CONFIG_LIBC_PERROR_STDOUT=y
+CONFIG_LIBC_STRERROR=y
+CONFIG_NFILE_DESCRIPTORS_PER_BLOCK=6
+CONFIG_NSH_ARCHINIT=y
+CONFIG_NSH_BUILTIN_APPS=y
+CONFIG_NSH_FILEIOSIZE=512
+CONFIG_NSH_READLINE=y
+CONFIG_NSH_STRERROR=y
+CONFIG_PREALLOC_TIMERS=0
+CONFIG_RR_INTERVAL=200
+CONFIG_SCHED_BACKTRACE=y
+CONFIG_SCHED_WAITPID=y
+CONFIG_START_DAY=29
+CONFIG_START_MONTH=11
+CONFIG_START_YEAR=2019
+CONFIG_SYSTEM_DUMPSTACK=y
+CONFIG_SYSTEM_NSH=y
+CONFIG_TESTING_GETPRIME=y
+CONFIG_TESTING_OSTEST=y
+CONFIG_UART0_SERIAL_CONSOLE=y
+CONFIG_HAVE_CXX=y
+CONFIG_LIBC_LOCALE=y
+CONFIG_LIBCXX=y
+CONFIG_LIBCXXABI=y
+CONFIG_CXX_EXCEPTION=y
+CONFIG_CXX_RTTI=y
+CONFIG_TESTING_CXXTEST=y
+CONFIG_TLS_NELEM=16
+CONFIG_TLS_TASK_NELEM=8
+CONFIG_CXX_LOCALIZATION=y
+CONFIG_CXX_WCHAR=y
+CONFIG_EXAMPLES_HELLOXX=y

libs/libxx/libcxxabi/src/cxa_exception_storage_stub.cpp

@@ -7,29 +7,32 @@
 //===----------------------------------------------------------------------===//
 
 // ============================================================================
-// CRITICAL SAFETY WARNING - READ BEFORE USE
+// EXCEPTION STORAGE IMPLEMENTATION FOR NUTTX
 // ============================================================================
 //
-// This implementation uses a SINGLE GLOBAL exception state without any
-// synchronization mechanism. It is ONLY safe under these conditions:
+// This implementation provides THREAD-SAFE per-task exception storage using
+// NuttX Task Local Storage (TLS). It is safe for use in multi-tasking RTOS
+// environments.
 //
-// 1. Single-threaded execution (no RTOS task switching during exception
-// handling)
-// 2. No interrupt-based exception throwing
-// 3. No concurrent exception handling across tasks
-// 4. _LIBCPP_HAS_NO_THREADS must be defined at compile time
+// SAFETY FEATURES:
+// 1. Per-task exception state using NuttX TLS (no shared global state)
+// 2. Interrupt-safe initialization using enter_critical_section()
+// 3. Automatic cleanup on task exit via TLS destructor
+// 4. Double-checked locking pattern for initialization
 //
-// UNSAFE SCENARIOS (will cause data corruption):
+// SAFE SCENARIOS:
 // - Multiple RTOS tasks throwing exceptions simultaneously
-// - Exception thrown from ISR while task is handling exception
-// - Nested exceptions across different execution contexts
+// - Task preemption during exception handling
+// - Nested exceptions within the same task
 //
-// FOR MULTI-THREADED SYSTEMS:
-// Implement per-task exception storage using NuttX TLS or task-local storage.
+// LIMITATIONS:
+// - Exception thrown from ISR context is NOT supported (use error codes)
+// - Requires CONFIG_TLS_TASK_NELEM >= 1 for TLS storage
 //
-// RECOMMENDED FOR CRITICAL SYSTEMS:
-// Disable C++ exceptions entirely (CONFIG_CXX_EXCEPTION=n) and use
-// error codes instead.
+// MEMORY USAGE PER TASK:
+// - sizeof(__cxa_eh_globals) bytes allocated on first exception (typically ~48
+// bytes)
+// - Automatically freed when task exits
 // ============================================================================
 
 #include "../libcxxabi/src/cxa_exception.h"
@@ -38,6 +41,7 @@
 #include <cstring>
 
 // Use NuttX Task Local Storage for per-task exception state
+#include <nuttx/irq.h>
 #include <nuttx/tls.h>
 
 // Compile-time safety check: ensure threading is disabled for libcxx
@@ -50,20 +54,37 @@ namespace __cxxabiv1 {
 
 // Per-task exception storage using NuttX TLS
 // This is THREAD-SAFE and works correctly with NuttX RTOS task switching
-static int tls_key = -1;
+static volatile int tls_key = -1;
 
-// Initialize TLS key on first use (lazy initialization)
+// Initialize TLS key on first use (lazy initialization with interrupt
+// protection) SAFETY: Uses interrupt disabling to prevent race conditions
+// during initialization
 static void init_tls_key() {
+  // Fast path: key already initialized (no locking needed for reads)
+  if (tls_key >= 0) {
+    return;
+  }
+
+  // Critical section: disable interrupts to prevent race condition
+  irqstate_t flags = enter_critical_section();
+
+  // Double-check: another task might have initialized while we waited
   if (tls_key == -1) {
     // Allocate TLS slot with destructor to free memory on task exit
-    tls_key = task_tls_alloc([](void *ptr) {
+    int new_key = task_tls_alloc([](void *ptr) {
       if (ptr) {
         free(ptr);
       }
     });
-    // Verify allocation succeeded
-    assert(tls_key >= 0 && "Failed to allocate TLS key for exception storage");
+
+    // Verify allocation succeeded before storing
+    assert(new_key >= 0 && "Failed to allocate TLS key for exception storage");
+
+    // Atomic write: store the key (volatile ensures visibility)
+    tls_key = new_key;
   }
+
+  leave_critical_section(flags);
 }
 
 extern __cxa_eh_globals *__cxa_get_globals() {