+static int
+altstack_pointer_p (void *p) {
+#ifndef LISP_FEATURE_WIN32
+ void* stack_start = arch_os_get_current_thread() + dynamic_values_bytes;
+ void* stack_end = stack_start + 32*SIGSTKSZ;
+
+ return (p > stack_start && p <= stack_end);
+#else
+ /* Win32 doesn't do altstack */
+ return 0;
+#endif
+}
+
+static int
+stack_pointer_p (void *p)
+{
+ /* we are using sizeof(long) here, because that is the right value on both
+ * x86 and x86-64. (But note that false positives would not cause much harm
+ * given the heuristical nature of x86_call_context.) */
+ unsigned long stack_alignment = sizeof(long);
+
+ return (altstack_pointer_p(p)
+ || (p < (void *) arch_os_get_current_thread()->control_stack_end
+ && (p > (void *) &p || altstack_pointer_p(&p))
+ && (((unsigned long) p) & (stack_alignment-1)) == 0));
+}
+
+static int
+ra_pointer_p (void *ra)
+{
+ /* the check against 4096 is still a mystery to everyone interviewed about
+ * it, but recent changes to sb-sprof seem to suggest that such values
+ * do occur sometimes. */
+ return ((unsigned long) ra) > 4096 && !stack_pointer_p (ra);
+}
+
+static int
+x86_call_context (void *fp, void **ra, void **ocfp)
+{
+ void *c_ocfp;
+ void *c_ra;
+ int c_valid_p;
+
+ if (!stack_pointer_p(fp))
+ return 0;
+
+ c_ocfp = *((void **) fp);
+ c_ra = *((void **) fp + 1);
+
+ c_valid_p = (c_ocfp > fp
+ && stack_pointer_p(c_ocfp)
+ && ra_pointer_p(c_ra));
+
+ if (c_valid_p)
+ *ra = c_ra, *ocfp = c_ocfp;
+ else
+ return 0;
+
+ return 1;
+}
+
+struct compiled_debug_fun *
+debug_function_from_pc (struct code* code, void *pc)
+{
+ unsigned long code_header_len = sizeof(lispobj) * HeaderValue(code->header);
+ unsigned long offset
+ = (unsigned long) pc - (unsigned long) code - code_header_len;
+ struct compiled_debug_fun *df;
+ struct compiled_debug_info *di;
+ struct vector *v;
+ int i, len;
+
+ if (lowtag_of(code->debug_info) != INSTANCE_POINTER_LOWTAG)
+ return 0;
+
+ di = (struct compiled_debug_info *) native_pointer(code->debug_info);
+ v = (struct vector *) native_pointer(di->fun_map);
+ len = fixnum_value(v->length);
+ df = (struct compiled_debug_fun *) native_pointer(v->data[0]);
+
+ if (len == 1)
+ return df;
+
+ for (i = 1;; i += 2) {
+ unsigned next_pc;
+
+ if (i == len)
+ return ((struct compiled_debug_fun *) native_pointer(v->data[i - 1]));
+
+ if (offset >= (unsigned long)fixnum_value(df->elsewhere_pc)) {
+ struct compiled_debug_fun *p
+ = ((struct compiled_debug_fun *) native_pointer(v->data[i + 1]));
+ next_pc = fixnum_value(p->elsewhere_pc);
+ } else
+ next_pc = fixnum_value(v->data[i]);
+
+ if (offset < next_pc)
+ return ((struct compiled_debug_fun *) native_pointer(v->data[i - 1]));
+ }
+
+ return NULL;
+}
+
+static void
+sbcl_putwc(wchar_t c, FILE *file)
+{
+#ifdef LISP_FEATURE_OS_PROVIDES_PUTWC
+ putwc(c, file);
+#else
+ if (c < 256) {
+ fputc(c, file);
+ } else {
+ fputc('?', file);
+ }
+#endif
+}
+
+static void
+print_string (lispobj *object)
+{
+ int tag = widetag_of(*object);
+ struct vector *vector = (struct vector *) object;
+
+#define doit(TYPE) \
+ do { \
+ int i; \
+ int n = fixnum_value(vector->length); \
+ TYPE *data = (TYPE *) vector->data; \
+ for (i = 0; i < n; i++) { \
+ wchar_t c = (wchar_t) data[i]; \
+ if (c == '\\' || c == '"') \
+ putchar('\\'); \
+ sbcl_putwc(c, stdout); \
+ } \
+ } while (0)
+
+ switch (tag) {
+ case SIMPLE_BASE_STRING_WIDETAG:
+ doit(unsigned char);
+ break;
+#ifdef SIMPLE_CHARACTER_STRING_WIDETAG
+ case SIMPLE_CHARACTER_STRING_WIDETAG:
+ doit(unsigned int);
+ break;
+#endif
+ default:
+ printf("<??? type %d>", tag);
+ }
+#undef doit
+}
+
+static void
+print_entry_name (lispobj name)
+{
+ if (lowtag_of (name) == LIST_POINTER_LOWTAG) {
+ putchar('(');
+ while (name != NIL) {
+ struct cons *cons = (struct cons *) native_pointer(name);
+ print_entry_name(cons->car);
+ name = cons->cdr;
+ if (name != NIL)
+ putchar(' ');
+ }
+ putchar(')');
+ } else if (lowtag_of(name) == OTHER_POINTER_LOWTAG) {
+ lispobj *object = (lispobj *) native_pointer(name);
+ if (widetag_of(*object) == SYMBOL_HEADER_WIDETAG) {
+ struct symbol *symbol = (struct symbol *) object;
+ if (symbol->package != NIL) {
+ struct package *pkg
+ = (struct package *) native_pointer(symbol->package);
+ lispobj pkg_name = pkg->_name;
+ print_string(native_pointer(pkg_name));
+ fputs("::", stdout);
+ }
+ print_string(native_pointer(symbol->name));
+ } else if (widetag_of(*object) == SIMPLE_BASE_STRING_WIDETAG) {
+ putchar('"');
+ print_string(object);
+ putchar('"');
+#ifdef SIMPLE_CHARACTER_STRING_WIDETAG
+ } else if (widetag_of(*object) == SIMPLE_CHARACTER_STRING_WIDETAG) {
+ putchar('"');
+ print_string(object);
+ putchar('"');
+#endif
+ } else {
+ printf("<??? type %d>", (int) widetag_of(*object));
+ }
+ } else {
+ printf("<??? lowtag %d>", (int) lowtag_of(name));
+ }
+}
+
+static void
+print_entry_points (struct code *code)
+{
+ lispobj function = code->entry_points;
+
+ while (function != NIL) {
+ struct simple_fun *header = (struct simple_fun *) native_pointer(function);
+ print_entry_name(header->name);
+
+ function = header->next;
+ if (function != NIL)
+ printf (", ");
+ }
+}
+
+void
+describe_thread_state(void)
+{
+ sigset_t mask;
+ struct thread *thread = arch_os_get_current_thread();
+ struct interrupt_data *data = thread->interrupt_data;
+#ifndef LISP_FEATURE_WIN32
+ get_current_sigmask(&mask);
+ printf("Signal mask:\n");
+ printf(" SIGALRM = %d\n", sigismember(&mask, SIGALRM));
+ printf(" SIGINT = %d\n", sigismember(&mask, SIGINT));
+ printf(" SIGPROF = %d\n", sigismember(&mask, SIGPROF));
+#ifdef SIG_STOP_FOR_GC
+ printf(" SIG_STOP_FOR_GC = %d\n", sigismember(&mask, SIG_STOP_FOR_GC));
+#endif
+#endif
+ printf("Specials:\n");
+ printf(" *GC-INHIBIT* = %s\n", (SymbolValue(GC_INHIBIT, thread) == T) ? "T" : "NIL");
+ printf(" *GC-PENDING* = %s\n",
+ (SymbolValue(GC_PENDING, thread) == T) ?
+ "T" : ((SymbolValue(GC_PENDING, thread) == NIL) ?
+ "NIL" : ":IN-PROGRESS"));
+ printf(" *INTERRUPTS-ENABLED* = %s\n", (SymbolValue(INTERRUPTS_ENABLED, thread) == T) ? "T" : "NIL");
+#ifdef STOP_FOR_GC_PENDING
+ printf(" *STOP-FOR-GC-PENDING* = %s\n", (SymbolValue(STOP_FOR_GC_PENDING, thread) == T) ? "T" : "NIL");
+#endif
+ printf("Pending handler = %p\n", data->pending_handler);
+}
+
+/* This function has been split from backtrace() to enable Lisp
+ * backtraces from gdb with call backtrace_from_fp(...). Useful for
+ * example when debugging threading deadlocks.
+ */
+void
+backtrace_from_fp(void *fp, int nframes)
+{
+ int i;
+
+ for (i = 0; i < nframes; ++i) {
+ lispobj *p;
+ void *ra;
+ void *next_fp;
+
+ if (!x86_call_context(fp, &ra, &next_fp))
+ break;
+
+ printf("%4d: ", i);
+
+ p = (lispobj *) component_ptr_from_pc((lispobj *) ra);
+ if (p) {
+ struct code *cp = (struct code *) p;
+ struct compiled_debug_fun *df = debug_function_from_pc(cp, ra);
+ if (df)
+ print_entry_name(df->name);
+ else
+ print_entry_points(cp);
+ } else {
+#ifdef LISP_FEATURE_OS_PROVIDES_DLADDR
+ Dl_info info;
+ if (dladdr(ra, &info)) {
+ printf("Foreign function %s, fp = 0x%lx, ra = 0x%lx",
+ info.dli_sname,
+ (unsigned long) next_fp,
+ (unsigned long) ra);
+ } else
+#endif
+ printf("Foreign fp = 0x%lx, ra = 0x%lx",
+ (unsigned long) next_fp,
+ (unsigned long) ra);
+ }
+
+ putchar('\n');
+ fp = next_fp;
+ }
+}
+