Enable AVM_ABORT() and use it for hard_fault_handler on stm32

- Impliment newlib stubs to support `getpid()` and `kill()` needed for
`AVM_ABORT()` to work properly.
- Redefine weak linked `hard_fault_handler` defined in libopencm3/cm3/nvic.h to
use `AVM_ABORT()` rather than get trapped in the default do nothing `while(1)`
loop.

Signed-off-by: Winford <[email protected]>

CHANGELOG.md

@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Fixed a bug where guards would raise exceptions instead of just being false
+- Fixed STM32 not aborting when `AVM_ABORT()` is used
+- Fixed a bug that would leave the STM32 trapped in a loop on hard faults, rather than aborting
 
 ## [0.6.0-alpha.1] - 2023-10-09
 

src/platforms/stm32/src/main.c

@@ -19,6 +19,7 @@
  */
 
 #include <errno.h>
+#include <signal.h>
 #include <stdio.h>
 #include <unistd.h>
 
@@ -61,6 +62,8 @@
     "\n"
 
 int _write(int file, char *ptr, int len);
+pid_t _getpid(void);
+int _kill(pid_t pid, int sig);
 
 static void clock_setup()
 {
@@ -124,6 +127,30 @@ int _write(int file, char *ptr, int len)
     return -1;
 }
 
+// newlib stubs to support AVM_ABORT
+pid_t _getpid()
+{
+    return 1;
+}
+
+int _kill(pid_t pid, int sig)
+{
+    UNUSED(pid);
+    if (sig == SIGABRT) {
+        fprintf(stderr, "Aborted\n");
+    } else {
+        fprintf(stderr, "Unknown signal %d\n", sig);
+    }
+    errno = EINVAL;
+    return -1;
+}
+
+// Redefine weak linked while(1) loop from libopencm3/cm3/nvic.h.
+void hard_fault_handler() {
+    fprintf(stderr, "\nHard Fault detected!\n");
+    AVM_ABORT();
+}
+
 int main()
 {
     clock_setup();