Revert "Cherry-pick of ocaml/ocaml 1eeb0e7fe595f5f9e1ea1edbdf785ff3b49feeeb (#12)"

This reverts commit b819c66.

Author: lpw25

otherlibs/systhreads/st_stubs.c

@@ -133,7 +133,6 @@ static st_retcode caml_threadstatus_wait (value);
 #ifdef NATIVE_CODE
 extern struct longjmp_buffer caml_termination_jmpbuf;
 extern void (*caml_termination_hook)(void);
-extern int caml_stop_stack_overflow_detection(void);
 #endif
 
 /* Hook for scanning the stacks of the other threads */
@@ -544,7 +543,6 @@ static ST_THREAD_FUNCTION caml_thread_start(void * arg)
     caml_thread_stop();
 #ifdef NATIVE_CODE
   }
-  caml_stop_stack_overflow_detection();
 #endif
   /* The thread now stops running */
   return 0;

runtime/fail_nat.c

@@ -32,8 +32,6 @@
 #include "caml/roots.h"
 #include "caml/callback.h"
 
-extern void caml_terminate_signals(void);
-
 /* The globals holding predefined exceptions */
 
 typedef value caml_generated_constant[1];
@@ -72,10 +70,7 @@ void caml_raise(value v)
   if (Is_exception_result(v))
     v = Extract_exception(v);
 
-  if (Caml_state->exception_pointer == NULL) {
-    caml_terminate_signals();
-    caml_fatal_uncaught_exception(v);
-  }
+  if (Caml_state->exception_pointer == NULL) caml_fatal_uncaught_exception(v);
 
   while (Caml_state->local_roots != NULL &&
          (char *) Caml_state->local_roots < Caml_state->exception_pointer) {

runtime/signals_nat.c

@@ -174,6 +174,8 @@ DECLARE_SIGNAL_HANDLER(trap_handler)
 #error "CONTEXT_SP is required if HAS_STACK_OVERFLOW_DETECTION is defined"
 #endif
 
+static char sig_alt_stack[SIGSTKSZ];
+
 /* Code compiled with ocamlopt never accesses more than
    EXTRA_STACK bytes below the stack pointer. */
 #define EXTRA_STACK 256
@@ -243,10 +245,6 @@ DECLARE_SIGNAL_HANDLER(segv_handler)
 
 /* Initialization of signal stuff */
 
-#ifdef HAS_STACK_OVERFLOW_DETECTION
-static int setup_stack_overflow_detection(void);
-#endif
-
 void caml_init_signals(void)
 {
   /* Bound-check trap handling */
@@ -271,91 +269,28 @@ void caml_init_signals(void)
 #endif
 
 #ifdef HAS_STACK_OVERFLOW_DETECTION
-  if (setup_stack_overflow_detection() != -1) {
+  {
+    stack_t stk;
     struct sigaction act;
+    stk.ss_sp = sig_alt_stack;
+    stk.ss_size = SIGSTKSZ;
+    stk.ss_flags = 0;
     SET_SIGACT(act, segv_handler);
     act.sa_flags |= SA_ONSTACK | SA_NODEFER;
     sigemptyset(&act.sa_mask);
-    sigaction(SIGSEGV, &act, NULL);
+    if (sigaltstack(&stk, NULL) == 0) { sigaction(SIGSEGV, &act, NULL); }
   }
 #endif
 }
 
-/* Termination of signal stuff */
-
-#if defined(TARGET_power) || defined(TARGET_s390x) \
-    || defined(HAS_STACK_OVERFLOW_DETECTION)
-static void set_signal_default(int signum)
-{
-  struct sigaction act;
-  sigemptyset(&act.sa_mask);
-  act.sa_handler = SIG_DFL;
-  act.sa_flags = 0;
-  sigaction(signum, &act, NULL);
-}
-#endif
-
-int caml_stop_stack_overflow_detection(void);
-
-void caml_terminate_signals(void)
+CAMLexport void caml_setup_stack_overflow_detection(void)
 {
-#if defined(TARGET_power)
-  set_signal_default(SIGTRAP);
-#endif
-
-#if defined(TARGET_s390x)
-  set_signal_default(SIGFPE);
-#endif
-
 #ifdef HAS_STACK_OVERFLOW_DETECTION
-  set_signal_default(SIGSEGV);
-  caml_stop_stack_overflow_detection();
-#endif
-}
-
-/* Allocate and select an alternate stack for handling signals,
-   especially SIGSEGV signals.
-   Each thread needs its own alternate stack.
-   The alternate stack used to be statically-allocated for the main thread,
-   but this is incompatible with Glibc 2.34 and newer, where SIGSTKSZ
-   may not be a compile-time constant (issue #10250). */
-
-#ifdef HAS_STACK_OVERFLOW_DETECTION
-static int setup_stack_overflow_detection(void)
-{
   stack_t stk;
   stk.ss_sp = malloc(SIGSTKSZ);
-  if (stk.ss_sp == NULL) return -1;
   stk.ss_size = SIGSTKSZ;
   stk.ss_flags = 0;
-  if (sigaltstack(&stk, NULL) == -1) {
-    free(stk.ss_sp);
-    return -1;
-  }
-  /* Success (or stack overflow detection not available) */
-  return 0;
-}
-#endif
-
-CAMLexport void caml_setup_stack_overflow_detection(void)
-{
-#ifdef HAS_STACK_OVERFLOW_DETECTION
-  setup_stack_overflow_detection();
-#endif
-}
-
-CAMLexport int caml_stop_stack_overflow_detection(void)
-{
-#ifdef HAS_STACK_OVERFLOW_DETECTION
-  stack_t oldstk, stk;
-  stk.ss_flags = SS_DISABLE;
-  if (sigaltstack(&stk, &oldstk) == -1) return -1;
-  /* If caml_setup_stack_overflow_detection failed, we are not using
-     an alternate signal stack.  SS_DISABLE will be set in oldstk,
-     and there is nothing to free in this case. */
-  if (! (oldstk.ss_flags & SS_DISABLE)) free(oldstk.ss_sp);
-  return 0;
-#else
-  return 0;
+  if (stk.ss_sp)
+    sigaltstack(&stk, NULL);
 #endif
 }

runtime/startup_nat.c

@@ -92,7 +92,6 @@ void (*caml_termination_hook)(void *) = NULL;
 
 extern value caml_start_program (caml_domain_state*);
 extern void caml_init_signals (void);
-extern void caml_terminate_signals(void);
 #ifdef _WIN32
 extern void caml_win32_overflow_detection (void);
 #endif
@@ -107,7 +106,6 @@ extern void caml_install_invalid_parameter_handler();
 value caml_startup_common(char_os **argv, int pooling)
 {
   char_os * exe_name, * proc_self_exe;
-  value res;
   char tos;
 
   /* Initialize the domain */
@@ -154,13 +152,10 @@ value caml_startup_common(char_os **argv, int pooling)
     exe_name = caml_search_exe_in_path(exe_name);
   caml_sys_init(exe_name, argv);
   if (sigsetjmp(caml_termination_jmpbuf.buf, 0)) {
-    caml_terminate_signals();
     if (caml_termination_hook != NULL) caml_termination_hook(NULL);
     return Val_unit;
   }
-  res = caml_start_program(Caml_state);
-  caml_terminate_signals();
-  return res;
+  return caml_start_program(Caml_state);
 }
 
 value caml_startup_exn(char_os **argv)

runtime/sys.c

@@ -112,8 +112,6 @@ static void caml_sys_check_path(value name)
   }
 }
 
-extern void caml_terminate_signals(void);
-
 CAMLprim value caml_sys_exit(value retcode_v)
 {
   int retcode = Int_val(retcode_v);
@@ -161,9 +159,6 @@ CAMLprim value caml_sys_exit(value retcode_v)
     caml_shutdown();
 #ifdef _WIN32
   caml_restore_win32_terminal();
-#endif
-#ifdef NATIVE_CODE
-  caml_terminate_signals();
 #endif
   exit(retcode);
 }