Merge pull request JuliaLang#11517 from JuliaLang/kf/segvexc

Add an option to turn segfaults into julia errors
inkydragon · Jun 1, 2015 · 3c853e2 · 3c853e2
2 parents 25923b1 + ccab029
commit 3c853e2
Show file tree

Hide file tree

Showing 6 changed files with 47 additions and 1 deletion.
diff --git a/base/boot.jl b/base/boot.jl
@@ -136,7 +136,7 @@ export
  # errors
  BoundsError, DivideError, DomainError, Exception,
  InexactError, InterruptException, OutOfMemoryError, OverflowError,
- StackOverflowError, UndefRefError, UndefVarError,
+ StackOverflowError, SegmentationFault, UndefRefError, UndefVarError,
  # AST representation
  Expr, GotoNode, LabelNode, LineNumberNode, QuoteNode, SymbolNode, TopNode,
  GlobalRef, NewvarNode, GenSym,
@@ -218,6 +218,7 @@ immutable DomainError <: Exception end
 immutable OverflowError <: Exception end
 immutable InexactError <: Exception end
 immutable OutOfMemoryError <: Exception end
+immutable SegmentationFault <: Exception end
 immutable StackOverflowError <: Exception end
 immutable UndefRefError <: Exception end
 immutable UndefVarError <: Exception

diff --git a/base/essentials.jl b/base/essentials.jl
@@ -15,6 +15,7 @@ call(T::Type{OverflowError}) = Core.call(T)
 call(T::Type{InexactError}) = Core.call(T)
 call(T::Type{OutOfMemoryError}) = Core.call(T)
 call(T::Type{StackOverflowError}) = Core.call(T)
+call(T::Type{SegmentationFault}) = Core.call(T)
 call(T::Type{UndefRefError}) = Core.call(T)
 call(T::Type{UndefVarError}, var::Symbol) = Core.call(T, var)
 call(T::Type{InterruptException}) = Core.call(T)

diff --git a/src/alloc.c b/src/alloc.c
@@ -62,6 +62,9 @@ jl_datatype_t *jl_void_type;
 jl_datatype_t *jl_voidpointer_type;
 jl_value_t *jl_an_empty_cell=NULL;
 jl_value_t *jl_stackovf_exception;
+#ifdef SEGV_EXCEPTION
+jl_value_t *jl_segv_exception;
+#endif
 jl_value_t *jl_diverror_exception;
 jl_value_t *jl_domain_exception;
 jl_value_t *jl_overflow_exception;

diff --git a/src/init.c b/src/init.c
@@ -290,9 +290,18 @@ void segv_handler(int sig, siginfo_t *info, void *context)
  sigprocmask(SIG_UNBLOCK, &sset, NULL);
  jl_throw(jl_memory_exception);
  }
+#ifdef SEGV_EXCEPTION
+ else {
+ sigemptyset(&sset);
+ sigaddset(&sset, SIGSEGV);
+ sigprocmask(SIG_UNBLOCK, &sset, NULL);
+ jl_throw(jl_segv_exception);
+ }
+#else
  else {
  sigdie_handler(sig, info, context);
  }
+#endif
 }
 #endif
 
@@ -747,6 +756,17 @@ void *mach_segv_listener(void *arg)
  }
 }
 
+#ifdef SEGV_EXCEPTION
+
+void darwin_segv_handler(unw_context_t *uc)
+{
+ bt_size = rec_backtrace_ctx(bt_data, MAX_BT_SIZE, uc);
+ jl_exception_in_transit = jl_segv_exception;
+ jl_rethrow();
+}
+
+#endif
+
 void darwin_stack_overflow_handler(unw_context_t *uc)
 {
  bt_size = rec_backtrace_ctx(bt_data, MAX_BT_SIZE, uc);
@@ -799,8 +819,12 @@ kern_return_t catch_exception_raise(mach_port_t exception_port,
  ret = thread_get_state(thread,x86_EXCEPTION_STATE64,(thread_state_t)&exc_state,&exc_count);
  HANDLE_MACH_ERROR("thread_get_state(1)",ret);
  uint64_t fault_addr = exc_state.__faultvaddr;
+#ifdef SEGV_EXCEPTION
+ if (1) {
+#else
  if (is_addr_on_stack((void*)fault_addr) ||
  ((exc_state.__err & PAGE_PRESENT) == PAGE_PRESENT)) {
+#endif
  ret = thread_get_state(thread,x86_THREAD_STATE64,(thread_state_t)&state,&count);
  HANDLE_MACH_ERROR("thread_get_state(2)",ret);
  old_state = state;
@@ -823,6 +847,10 @@ kern_return_t catch_exception_raise(mach_port_t exception_port,
  state.__rdi = (uint64_t)uc;
  if ((exc_state.__err & PAGE_PRESENT) == PAGE_PRESENT)
  state.__rip = (uint64_t)darwin_accerr_handler;
+#ifdef SEGV_EXCEPTION
+ else if (!is_addr_on_stack((void*)fault_addr))
+ state.__rip = (uint64_t)darwin_segv_handler;
+#endif
  else
  state.__rip = (uint64_t)darwin_stack_overflow_handler;
 
@@ -1341,6 +1369,10 @@ void jl_get_builtin_hooks(void)
  jl_boundserror_type = (jl_datatype_t*)core("BoundsError");
  jl_memory_exception = jl_new_struct_uninit((jl_datatype_t*)core("OutOfMemoryError"));
 
+#ifdef SEGV_EXCEPTION
+ jl_segv_exception = jl_new_struct_uninit((jl_datatype_t*)core("SegmentationFault"));
+#endif
+
  jl_ascii_string_type = (jl_datatype_t*)core("ASCIIString");
  jl_utf8_string_type = (jl_datatype_t*)core("UTF8String");
  jl_symbolnode_type = (jl_datatype_t*)core("SymbolNode");

diff --git a/src/julia_internal.h b/src/julia_internal.h
@@ -180,6 +180,10 @@ DLLEXPORT void jl_atexit_hook();
 #define HAVE_CPUID
 #endif
 
+#ifdef SEGV_EXCEPTION
+extern DLLEXPORT jl_value_t *jl_segv_exception;
+#endif
+
 #ifdef __cplusplus
 }
 #endif

diff --git a/src/options.h b/src/options.h
@@ -49,6 +49,11 @@
 // reachable memory is freed
 //#define GC_VERIFY
 
+// SEGV_EXCEPTION turns segmentation faults into catchable julia exceptions.
+// This is not recommended, as the memory state after such an exception should
+// be considered untrusted, but can be helpful during development
+// #define SEGV_EXCEPTION
+
 // profiling options
 
 // GC_FINAL_STATS prints total GC stats at exit