/* Perform an inferior function call, for GDB, the GNU debugger. Copyright (C) 1986-2020 Free Software Foundation, Inc. This file is part of GDB. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ #include "defs.h" #include "infcall.h" #include "breakpoint.h" #include "tracepoint.h" #include "target.h" #include "regcache.h" #include "inferior.h" #include "infrun.h" #include "block.h" #include "gdbcore.h" #include "language.h" #include "objfiles.h" #include "gdbcmd.h" #include "command.h" #include "dummy-frame.h" #include "ada-lang.h" #include "f-lang.h" #include "gdbthread.h" #include "event-top.h" #include "observable.h" #include "top.h" #include "interps.h" #include "thread-fsm.h" #include <algorithm> #include "gdbsupport/scope-exit.h" #include <list> /* If we can't find a function's name from its address, we print this instead. */ #define RAW_FUNCTION_ADDRESS_FORMAT "at 0x%s" #define RAW_FUNCTION_ADDRESS_SIZE (sizeof (RAW_FUNCTION_ADDRESS_FORMAT) \ + 2 * sizeof (CORE_ADDR)) /* NOTE: cagney/2003-04-16: What's the future of this code? GDB needs an asynchronous expression evaluator, that means an asynchronous inferior function call implementation, and that in turn means restructuring the code so that it is event driven. */ static bool may_call_functions_p = true; static void show_may_call_functions_p (struct ui_file *file, int from_tty, struct cmd_list_element *c, const char *value) { fprintf_filtered (file, _("Permission to call functions in the program is %s.\n"), value); } /* How you should pass arguments to a function depends on whether it was defined in K&R style or prototype style. If you define a function using the K&R syntax that takes a `float' argument, then callers must pass that argument as a `double'. If you define the function using the prototype syntax, then you must pass the argument as a `float', with no promotion. Unfortunately, on certain older platforms, the debug info doesn't indicate reliably how each function was defined. A function type's TYPE_PROTOTYPED flag may be clear, even if the function was defined in prototype style. When calling a function whose TYPE_PROTOTYPED flag is clear, GDB consults this flag to decide what to do. For modern targets, it is proper to assume that, if the prototype flag is clear, that can be trusted: `float' arguments should be promoted to `double'. For some older targets, if the prototype flag is clear, that doesn't tell us anything. The default is to trust the debug information; the user can override this behavior with "set coerce-float-to-double 0". */ static bool coerce_float_to_double_p = true; static void show_coerce_float_to_double_p (struct ui_file *file, int from_tty, struct cmd_list_element *c, const char *value) { fprintf_filtered (file, _("Coercion of floats to doubles " "when calling functions is %s.\n"), value); } /* This boolean tells what gdb should do if a signal is received while in a function called from gdb (call dummy). If set, gdb unwinds the stack and restore the context to what as it was before the call. The default is to stop in the frame where the signal was received. */ static bool unwind_on_signal_p = false; static void show_unwind_on_signal_p (struct ui_file *file, int from_tty, struct cmd_list_element *c, const char *value) { fprintf_filtered (file, _("Unwinding of stack if a signal is " "received while in a call dummy is %s.\n"), value); } /* This boolean tells what gdb should do if a std::terminate call is made while in a function called from gdb (call dummy). As the confines of a single dummy stack prohibit out-of-frame handlers from handling a raised exception, and as out-of-frame handlers are common in C++, this can lead to no handler being found by the unwinder, and a std::terminate call. This is a false positive. If set, gdb unwinds the stack and restores the context to what it was before the call. The default is to unwind the frame if a std::terminate call is made. */ static bool unwind_on_terminating_exception_p = true; static void show_unwind_on_terminating_exception_p (struct ui_file *file, int from_tty, struct cmd_list_element *c, const char *value) { fprintf_filtered (file, _("Unwind stack if a C++ exception is " "unhandled while in a call dummy is %s.\n"), value); } /* Perform the standard coercions that are specified for arguments to be passed to C, Ada or Fortran functions. If PARAM_TYPE is non-NULL, it is the expected parameter type. IS_PROTOTYPED is non-zero if the function declaration is prototyped. */ static struct value * value_arg_coerce (struct gdbarch *gdbarch, struct value *arg, struct type *param_type, int is_prototyped) { const struct builtin_type *builtin = builtin_type (gdbarch); struct type *arg_type = check_typedef (value_type (arg)); struct type *type = param_type ? check_typedef (param_type) : arg_type; /* Perform any Ada- and Fortran-specific coercion first. */ if (current_language->la_language == language_ada) arg = ada_convert_actual (arg, type); else if (current_language->la_language == language_fortran) type = fortran_preserve_arg_pointer (arg, type); /* Force the value to the target if we will need its address. At this point, we could allocate arguments on the stack instead of calling malloc if we knew that their addresses would not be saved by the called function. */ arg = value_coerce_to_target (arg); switch (type->code ()) { case TYPE_CODE_REF: case TYPE_CODE_RVALUE_REF: { struct value *new_value; if (TYPE_IS_REFERENCE (arg_type)) return value_cast_pointers (type, arg, 0); /* Cast the value to the reference's target type, and then convert it back to a reference. This will issue an error if the value was not previously in memory - in some cases we should clearly be allowing this, but how? */ new_value = value_cast (TYPE_TARGET_TYPE (type), arg); new_value = value_ref (new_value, type->code ()); return new_value; } case TYPE_CODE_INT: case TYPE_CODE_CHAR: case TYPE_CODE_BOOL: case TYPE_CODE_ENUM: /* If we don't have a prototype, coerce to integer type if necessary. */ if (!is_prototyped) { if (TYPE_LENGTH (type) < TYPE_LENGTH (builtin->builtin_int)) type = builtin->builtin_int; } /* Currently all target ABIs require at least the width of an integer type for an argument. We may have to conditionalize the following type coercion for future targets. */ if (TYPE_LENGTH (type) < TYPE_LENGTH (builtin->builtin_int)) type = builtin->builtin_int; break; case TYPE_CODE_FLT: if (!is_prototyped && coerce_float_to_double_p) { if (TYPE_LENGTH (type) < TYPE_LENGTH (builtin->builtin_double)) type = builtin->builtin_double; else if (TYPE_LENGTH (type) > TYPE_LENGTH (builtin->builtin_double)) type = builtin->builtin_long_double; } break; case TYPE_CODE_FUNC: type = lookup_pointer_type (type); break; case TYPE_CODE_ARRAY: /* Arrays are coerced to pointers to their first element, unless they are vectors, in which case we want to leave them alone, because they are passed by value. */ if (current_language->c_style_arrays_p ()) if (!type->is_vector ()) type = lookup_pointer_type (TYPE_TARGET_TYPE (type)); break; case TYPE_CODE_UNDEF: case TYPE_CODE_PTR: case TYPE_CODE_STRUCT: case TYPE_CODE_UNION: case TYPE_CODE_VOID: case TYPE_CODE_SET: case TYPE_CODE_RANGE: case TYPE_CODE_STRING: case TYPE_CODE_ERROR: case TYPE_CODE_MEMBERPTR: case TYPE_CODE_METHODPTR: case TYPE_CODE_METHOD: case TYPE_CODE_COMPLEX: default: break; } return value_cast (type, arg); } /* See infcall.h. */ CORE_ADDR find_function_addr (struct value *function, struct type **retval_type, struct type **function_type) { struct type *ftype = check_typedef (value_type (function)); struct gdbarch *gdbarch = get_type_arch (ftype); struct type *value_type = NULL; /* Initialize it just to avoid a GCC false warning. */ CORE_ADDR funaddr = 0; /* If it's a member function, just look at the function part of it. */ /* Determine address to call. */ if (ftype->code () == TYPE_CODE_FUNC || ftype->code () == TYPE_CODE_METHOD) funaddr = value_address (function); else if (ftype->code () == TYPE_CODE_PTR) { funaddr = value_as_address (function); ftype = check_typedef (TYPE_TARGET_TYPE (ftype)); if (ftype->code () == TYPE_CODE_FUNC || ftype->code () == TYPE_CODE_METHOD) funaddr = gdbarch_convert_from_func_ptr_addr (gdbarch, funaddr, current_top_target ()); } if (ftype->code () == TYPE_CODE_FUNC || ftype->code () == TYPE_CODE_METHOD) { if (ftype->is_gnu_ifunc ()) { CORE_ADDR resolver_addr = funaddr; /* Resolve the ifunc. Note this may call the resolver function in the inferior. */ funaddr = gnu_ifunc_resolve_addr (gdbarch, resolver_addr); /* Skip querying the function symbol if no RETVAL_TYPE or FUNCTION_TYPE have been asked for. */ if (retval_type != NULL || function_type != NULL) { type *target_ftype = find_function_type (funaddr); /* If we don't have debug info for the target function, see if we can instead extract the target function's type from the type that the resolver returns. */ if (target_ftype == NULL) target_ftype = find_gnu_ifunc_target_type (resolver_addr); if (target_ftype != NULL) { value_type = TYPE_TARGET_TYPE (check_typedef (target_ftype)); ftype = target_ftype; } } } else value_type = TYPE_TARGET_TYPE (ftype); } else if (ftype->code () == TYPE_CODE_INT) { /* Handle the case of functions lacking debugging info. Their values are characters since their addresses are char. */ if (TYPE_LENGTH (ftype) == 1) funaddr = value_as_address (value_addr (function)); else { /* Handle function descriptors lacking debug info. */ int found_descriptor = 0; funaddr = 0; /* pacify "gcc -Werror" */ if (VALUE_LVAL (function) == lval_memory) { CORE_ADDR nfunaddr; funaddr = value_as_address (value_addr (function)); nfunaddr = funaddr; funaddr = gdbarch_convert_from_func_ptr_addr (gdbarch, funaddr, current_top_target ()); if (funaddr != nfunaddr) found_descriptor = 1; } if (!found_descriptor) /* Handle integer used as address of a function. */ funaddr = (CORE_ADDR) value_as_long (function); } } else error (_("Invalid data type for function to be called.")); if (retval_type != NULL) *retval_type = value_type; if (function_type != NULL) *function_type = ftype; return funaddr + gdbarch_deprecated_function_start_offset (gdbarch); } /* For CALL_DUMMY_ON_STACK, push a breakpoint sequence that the called function returns to. */ static CORE_ADDR push_dummy_code (struct gdbarch *gdbarch, CORE_ADDR sp, CORE_ADDR funaddr, gdb::array_view<value *> args, struct type *value_type, CORE_ADDR *real_pc, CORE_ADDR *bp_addr, struct regcache *regcache) { gdb_assert (gdbarch_push_dummy_code_p (gdbarch)); return gdbarch_push_dummy_code (gdbarch, sp, funaddr, args.data (), args.size (), value_type, real_pc, bp_addr, regcache); } /* See infcall.h. */ void error_call_unknown_return_type (const char *func_name) { if (func_name != NULL) error (_("'%s' has unknown return type; " "cast the call to its declared return type"), func_name); else error (_("function has unknown return type; " "cast the call to its declared return type")); } /* Fetch the name of the function at FUNADDR. This is used in printing an error message for call_function_by_hand. BUF is used to print FUNADDR in hex if the function name cannot be determined. It must be large enough to hold formatted result of RAW_FUNCTION_ADDRESS_FORMAT. */ static const char * get_function_name (CORE_ADDR funaddr, char *buf, int buf_size) { { struct symbol *symbol = find_pc_function (funaddr); if (symbol) return symbol->print_name (); } { /* Try the minimal symbols. */ struct bound_minimal_symbol msymbol = lookup_minimal_symbol_by_pc (funaddr); if (msymbol.minsym) return msymbol.minsym->print_name (); } { std::string tmp = string_printf (_(RAW_FUNCTION_ADDRESS_FORMAT), hex_string (funaddr)); gdb_assert (tmp.length () + 1 <= buf_size); return strcpy (buf, tmp.c_str ()); } } /* All the meta data necessary to extract the call's return value. */ struct call_return_meta_info { /* The caller frame's architecture. */ struct gdbarch *gdbarch; /* The called function. */ struct value *function; /* The return value's type. */ struct type *value_type; /* Are we returning a value using a structure return or a normal value return? */ int struct_return_p; /* If using a structure return, this is the structure's address. */ CORE_ADDR struct_addr; }; /* Extract the called function's return value. */ static struct value * get_call_return_value (struct call_return_meta_info *ri) { struct value *retval = NULL; thread_info *thr = inferior_thread (); bool stack_temporaries = thread_stack_temporaries_enabled_p (thr); if (ri->value_type->code () == TYPE_CODE_VOID) retval = allocate_value (ri->value_type); else if (ri->struct_return_p) { if (stack_temporaries) { retval = value_from_contents_and_address (ri->value_type, NULL, ri->struct_addr); push_thread_stack_temporary (thr, retval); } else { retval = allocate_value (ri->value_type); read_value_memory (retval, 0, 1, ri->struct_addr, value_contents_raw (retval), TYPE_LENGTH (ri->value_type)); } } else { retval = allocate_value (ri->value_type); gdbarch_return_value (ri->gdbarch, ri->function, ri->value_type, get_current_regcache (), value_contents_raw (retval), NULL); if (stack_temporaries && class_or_union_p (ri->value_type)) { /* Values of class type returned in registers are copied onto the stack and their lval_type set to lval_memory. This is required because further evaluation of the expression could potentially invoke methods on the return value requiring GDB to evaluate the "this" pointer. To evaluate the this pointer, GDB needs the memory address of the value. */ value_force_lval (retval, ri->struct_addr); push_thread_stack_temporary (thr, retval); } } gdb_assert (retval != NULL); return retval; } /* Data for the FSM that manages an infcall. It's main job is to record the called function's return value. */ struct call_thread_fsm : public thread_fsm { /* All the info necessary to be able to extract the return value. */ struct call_return_meta_info return_meta_info; /* The called function's return value. This is extracted from the target before the dummy frame is popped. */ struct value *return_value = nullptr; /* The top level that started the infcall (and is synchronously waiting for it to end). */ struct ui *waiting_ui; call_thread_fsm (struct ui *waiting_ui, struct interp *cmd_interp, struct gdbarch *gdbarch, struct value *function, struct type *value_type, int struct_return_p, CORE_ADDR struct_addr); bool should_stop (struct thread_info *thread) override; bool should_notify_stop () override; }; /* Allocate a new call_thread_fsm object. */ call_thread_fsm::call_thread_fsm (struct ui *waiting_ui, struct interp *cmd_interp, struct gdbarch *gdbarch, struct value *function, struct type *value_type, int struct_return_p, CORE_ADDR struct_addr) : thread_fsm (cmd_interp), waiting_ui (waiting_ui) { return_meta_info.gdbarch = gdbarch; return_meta_info.function = function; return_meta_info.value_type = value_type; return_meta_info.struct_return_p = struct_return_p; return_meta_info.struct_addr = struct_addr; } /* Implementation of should_stop method for infcalls. */ bool call_thread_fsm::should_stop (struct thread_info *thread) { if (stop_stack_dummy == STOP_STACK_DUMMY) { /* Done. */ set_finished (); /* Stash the return value before the dummy frame is popped and registers are restored to what they were before the call.. */ return_value = get_call_return_value (&return_meta_info); /* Break out of wait_sync_command_done. */ scoped_restore save_ui = make_scoped_restore (¤t_ui, waiting_ui); target_terminal::ours (); waiting_ui->prompt_state = PROMPT_NEEDED; } return true; } /* Implementation of should_notify_stop method for infcalls. */ bool call_thread_fsm::should_notify_stop () { if (finished_p ()) { /* Infcall succeeded. Be silent and proceed with evaluating the expression. */ return false; } /* Something wrong happened. E.g., an unexpected breakpoint triggered, or a signal was intercepted. Notify the stop. */ return true; } /* Subroutine of call_function_by_hand to simplify it. Start up the inferior and wait for it to stop. Return the exception if there's an error, or an exception with reason >= 0 if there's no error. This is done inside a TRY_CATCH so the caller needn't worry about thrown errors. The caller should rethrow if there's an error. */ static struct gdb_exception run_inferior_call (struct call_thread_fsm *sm, struct thread_info *call_thread, CORE_ADDR real_pc) { struct gdb_exception caught_error; int saved_in_infcall = call_thread->control.in_infcall; ptid_t call_thread_ptid = call_thread->ptid; enum prompt_state saved_prompt_state = current_ui->prompt_state; int was_running = call_thread->state == THREAD_RUNNING; int saved_ui_async = current_ui->async; /* Infcalls run synchronously, in the foreground. */ current_ui->prompt_state = PROMPT_BLOCKED; /* So that we don't print the prompt prematurely in fetch_inferior_event. */ current_ui->async = 0; delete_file_handler (current_ui->input_fd); call_thread->control.in_infcall = 1; clear_proceed_status (0); /* Associate the FSM with the thread after clear_proceed_status (otherwise it'd clear this FSM), and before anything throws, so we don't leak it (and any resources it manages). */ call_thread->thread_fsm = sm; disable_watchpoints_before_interactive_call_start (); /* We want to print return value, please... */ call_thread->control.proceed_to_finish = 1; try { proceed (real_pc, GDB_SIGNAL_0); /* Inferior function calls are always synchronous, even if the target supports asynchronous execution. */ wait_sync_command_done (); } catch (gdb_exception &e) { caught_error = std::move (e); } /* If GDB has the prompt blocked before, then ensure that it remains so. normal_stop calls async_enable_stdin, so reset the prompt state again here. In other cases, stdin will be re-enabled by inferior_event_handler, when an exception is thrown. */ current_ui->prompt_state = saved_prompt_state; if (current_ui->prompt_state == PROMPT_BLOCKED) delete_file_handler (current_ui->input_fd); else ui_register_input_event_handler (current_ui); current_ui->async = saved_ui_async; /* If the infcall does NOT succeed, normal_stop will have already finished the thread states. However, on success, normal_stop defers here, so that we can set back the thread states to what they were before the call. Note that we must also finish the state of new threads that might have spawned while the call was running. The main cases to handle are: - "(gdb) print foo ()", or any other command that evaluates an expression at the prompt. (The thread was marked stopped before.) - "(gdb) break foo if return_false()" or similar cases where we do an infcall while handling an event (while the thread is still marked running). In this example, whether the condition evaluates true and thus we'll present a user-visible stop is decided elsewhere. */ if (!was_running && call_thread_ptid == inferior_ptid && stop_stack_dummy == STOP_STACK_DUMMY) finish_thread_state (call_thread->inf->process_target (), user_visible_resume_ptid (0)); enable_watchpoints_after_interactive_call_stop (); /* Call breakpoint_auto_delete on the current contents of the bpstat of inferior call thread. If all error()s out of proceed ended up calling normal_stop (and perhaps they should; it already does in the special case of error out of resume()), then we wouldn't need this. */ if (caught_error.reason < 0) { if (call_thread->state != THREAD_EXITED) breakpoint_auto_delete (call_thread->control.stop_bpstat); } call_thread->control.in_infcall = saved_in_infcall; return caught_error; } /* Reserve space on the stack for a value of the given type. Return the address of the allocated space. Make certain that the value is correctly aligned. The SP argument is modified. */ static CORE_ADDR reserve_stack_space (const type *values_type, CORE_ADDR &sp) { struct frame_info *frame = get_current_frame (); struct gdbarch *gdbarch = get_frame_arch (frame); CORE_ADDR addr = 0; if (gdbarch_inner_than (gdbarch, 1, 2)) { /* Stack grows downward. Align STRUCT_ADDR and SP after making space. */ sp -= TYPE_LENGTH (values_type); if (gdbarch_frame_align_p (gdbarch)) sp = gdbarch_frame_align (gdbarch, sp); addr = sp; } else { /* Stack grows upward. Align the frame, allocate space, and then again, re-align the frame??? */ if (gdbarch_frame_align_p (gdbarch)) sp = gdbarch_frame_align (gdbarch, sp); addr = sp; sp += TYPE_LENGTH (values_type); if (gdbarch_frame_align_p (gdbarch)) sp = gdbarch_frame_align (gdbarch, sp); } return addr; } /* The data structure which keeps a destructor function and its implicit 'this' parameter. */ struct destructor_info { destructor_info (struct value *function, struct value *self) : function (function), self (self) { } struct value *function; struct value *self; }; /* Auxiliary function that takes a list of destructor functions with their 'this' parameters, and invokes the functions. */ static void call_destructors (const std::list<destructor_info> &dtors_to_invoke, struct type *default_return_type) { for (auto vals : dtors_to_invoke) { call_function_by_hand (vals.function, default_return_type, gdb::make_array_view (&(vals.self), 1)); } } /* See infcall.h. */ struct value * call_function_by_hand (struct value *function, type *default_return_type, gdb::array_view<value *> args) { return call_function_by_hand_dummy (function, default_return_type, args, NULL, NULL); } /* All this stuff with a dummy frame may seem unnecessarily complicated (why not just save registers in GDB?). The purpose of pushing a dummy frame which looks just like a real frame is so that if you call a function and then hit a breakpoint (get a signal, etc), "backtrace" will look right. Whether the backtrace needs to actually show the stack at the time the inferior function was called is debatable, but it certainly needs to not display garbage. So if you are contemplating making dummy frames be different from normal frames, consider that. */ /* Perform a function call in the inferior. ARGS is a vector of values of arguments. FUNCTION is a value, the function to be called. Returns a value representing what the function returned. May fail to return, if a breakpoint or signal is hit during the execution of the function. ARGS is modified to contain coerced values. */ struct value * call_function_by_hand_dummy (struct value *function, type *default_return_type, gdb::array_view<value *> args, dummy_frame_dtor_ftype *dummy_dtor, void *dummy_dtor_data) { CORE_ADDR sp; struct type *target_values_type; function_call_return_method return_method = return_method_normal; CORE_ADDR struct_addr = 0; CORE_ADDR real_pc; CORE_ADDR bp_addr; struct frame_id dummy_id; struct frame_info *frame; struct gdbarch *gdbarch; ptid_t call_thread_ptid; struct gdb_exception e; char name_buf[RAW_FUNCTION_ADDRESS_SIZE]; if (!may_call_functions_p) error (_("Cannot call functions in the program: " "may-call-functions is off.")); if (!target_has_execution ()) noprocess (); if (get_traceframe_number () >= 0) error (_("May not call functions while looking at trace frames.")); if (execution_direction == EXEC_REVERSE) error (_("Cannot call functions in reverse mode.")); /* We're going to run the target, and inspect the thread's state afterwards. Hold a strong reference so that the pointer remains valid even if the thread exits. */ thread_info_ref call_thread = thread_info_ref::new_reference (inferior_thread ()); bool stack_temporaries = thread_stack_temporaries_enabled_p (call_thread.get ()); frame = get_current_frame (); gdbarch = get_frame_arch (frame); if (!gdbarch_push_dummy_call_p (gdbarch)) error (_("This target does not support function calls.")); /* Find the function type and do a sanity check. */ type *ftype; type *values_type; CORE_ADDR funaddr = find_function_addr (function, &values_type, &ftype); if (values_type == NULL) values_type = default_return_type; if (values_type == NULL) { const char *name = get_function_name (funaddr, name_buf, sizeof (name_buf)); error (_("'%s' has unknown return type; " "cast the call to its declared return type"), name); } values_type = check_typedef (values_type); if (args.size () < ftype->num_fields ()) error (_("Too few arguments in function call.")); /* A holder for the inferior status. This is only needed while we're preparing the inferior function call. */ infcall_control_state_up inf_status (save_infcall_control_state ()); /* Save the caller's registers and other state associated with the inferior itself so that they can be restored once the callee returns. To allow nested calls the registers are (further down) pushed onto a dummy frame stack. This unique pointer is released once the regcache has been pushed). */ infcall_suspend_state_up caller_state (save_infcall_suspend_state ()); /* Ensure that the initial SP is correctly aligned. */ { CORE_ADDR old_sp = get_frame_sp (frame); if (gdbarch_frame_align_p (gdbarch)) { sp = gdbarch_frame_align (gdbarch, old_sp); /* NOTE: cagney/2003-08-13: Skip the "red zone". For some ABIs, a function can use memory beyond the inner most stack address. AMD64 called that region the "red zone". Skip at least the "red zone" size before allocating any space on the stack. */ if (gdbarch_inner_than (gdbarch, 1, 2)) sp -= gdbarch_frame_red_zone_size (gdbarch); else sp += gdbarch_frame_red_zone_size (gdbarch); /* Still aligned? */ gdb_assert (sp == gdbarch_frame_align (gdbarch, sp)); /* NOTE: cagney/2002-09-18: On a RISC architecture, a void parameterless generic dummy frame (i.e., no parameters, no result) typically does not need to push anything the stack and hence can leave SP and FP. Similarly, a frameless (possibly leaf) function does not push anything on the stack and, hence, that too can leave FP and SP unchanged. As a consequence, a sequence of void parameterless generic dummy frame calls to frameless functions will create a sequence of effectively identical frames (SP, FP and TOS and PC the same). This, not surprisingly, results in what appears to be a stack in an infinite loop --- when GDB tries to find a generic dummy frame on the internal dummy frame stack, it will always find the first one. To avoid this problem, the code below always grows the stack. That way, two dummy frames can never be identical. It does burn a few bytes of stack but that is a small price to pay :-). */ if (sp == old_sp) { if (gdbarch_inner_than (gdbarch, 1, 2)) /* Stack grows down. */ sp = gdbarch_frame_align (gdbarch, old_sp - 1); else /* Stack grows up. */ sp = gdbarch_frame_align (gdbarch, old_sp + 1); } /* SP may have underflown address zero here from OLD_SP. Memory access functions will probably fail in such case but that is a target's problem. */ } else /* FIXME: cagney/2002-09-18: Hey, you loose! Who knows how badly aligned the SP is! If the generic dummy frame ends up empty (because nothing is pushed) GDB won't be able to correctly perform back traces. If a target is having trouble with backtraces, first thing to do is add FRAME_ALIGN() to the architecture vector. If that fails, try dummy_id(). If the ABI specifies a "Red Zone" (see the doco) the code below will quietly trash it. */ sp = old_sp; /* Skip over the stack temporaries that might have been generated during the evaluation of an expression. */ if (stack_temporaries) { struct value *lastval; lastval = get_last_thread_stack_temporary (call_thread.get ()); if (lastval != NULL) { CORE_ADDR lastval_addr = value_address (lastval); if (gdbarch_inner_than (gdbarch, 1, 2)) { gdb_assert (sp >= lastval_addr); sp = lastval_addr; } else { gdb_assert (sp <= lastval_addr); sp = lastval_addr + TYPE_LENGTH (value_type (lastval)); } if (gdbarch_frame_align_p (gdbarch)) sp = gdbarch_frame_align (gdbarch, sp); } } } /* Are we returning a value using a structure return? */ if (gdbarch_return_in_first_hidden_param_p (gdbarch, values_type)) { return_method = return_method_hidden_param; /* Tell the target specific argument pushing routine not to expect a value. */ target_values_type = builtin_type (gdbarch)->builtin_void; } else { if (using_struct_return (gdbarch, function, values_type)) return_method = return_method_struct; target_values_type = values_type; } gdb::observers::inferior_call_pre.notify (inferior_ptid, funaddr); /* Determine the location of the breakpoint (and possibly other stuff) that the called function will return to. The SPARC, for a function returning a structure or union, needs to make space for not just the breakpoint but also an extra word containing the size (?) of the structure being passed. */ switch (gdbarch_call_dummy_location (gdbarch)) { case ON_STACK: { const gdb_byte *bp_bytes; CORE_ADDR bp_addr_as_address; int bp_size; /* Be careful BP_ADDR is in inferior PC encoding while BP_ADDR_AS_ADDRESS is a plain memory address. */ sp = push_dummy_code (gdbarch, sp, funaddr, args, target_values_type, &real_pc, &bp_addr, get_current_regcache ()); /* Write a legitimate instruction at the point where the infcall breakpoint is going to be inserted. While this instruction is never going to be executed, a user investigating the memory from GDB would see this instruction instead of random uninitialized bytes. We chose the breakpoint instruction as it may look as the most logical one to the user and also valgrind 3.7.0 needs it for proper vgdb inferior calls. If software breakpoints are unsupported for this target we leave the user visible memory content uninitialized. */ bp_addr_as_address = bp_addr; bp_bytes = gdbarch_breakpoint_from_pc (gdbarch, &bp_addr_as_address, &bp_size); if (bp_bytes != NULL) write_memory (bp_addr_as_address, bp_bytes, bp_size); } break; case AT_ENTRY_POINT: { CORE_ADDR dummy_addr; real_pc = funaddr; dummy_addr = entry_point_address (); /* A call dummy always consists of just a single breakpoint, so its address is the same as the address of the dummy. The actual breakpoint is inserted separatly so there is no need to write that out. */ bp_addr = dummy_addr; break; } default: internal_error (__FILE__, __LINE__, _("bad switch")); } /* Coerce the arguments and handle pass-by-reference. We want to remember the destruction required for pass-by-ref values. For these, store the dtor function and the 'this' argument in DTORS_TO_INVOKE. */ std::list<destructor_info> dtors_to_invoke; for (int i = args.size () - 1; i >= 0; i--) { int prototyped; struct type *param_type; /* FIXME drow/2002-05-31: Should just always mark methods as prototyped. Can we respect TYPE_VARARGS? Probably not. */ if (ftype->code () == TYPE_CODE_METHOD) prototyped = 1; if (TYPE_TARGET_TYPE (ftype) == NULL && ftype->num_fields () == 0 && default_return_type != NULL) { /* Calling a no-debug function with the return type explicitly cast. Assume the function is prototyped, with a prototype matching the types of the arguments. E.g., with: float mult (float v1, float v2) { return v1 * v2; } This: (gdb) p (float) mult (2.0f, 3.0f) Is a simpler alternative to: (gdb) p ((float (*) (float, float)) mult) (2.0f, 3.0f) */ prototyped = 1; } else if (i < ftype->num_fields ()) prototyped = ftype->is_prototyped (); else prototyped = 0; if (i < ftype->num_fields ()) param_type = ftype->field (i).type (); else param_type = NULL; value *original_arg = args[i]; args[i] = value_arg_coerce (gdbarch, args[i], param_type, prototyped); if (param_type == NULL) continue; auto info = language_pass_by_reference (param_type); if (!info.copy_constructible) error (_("expression cannot be evaluated because the type '%s' " "is not copy constructible"), param_type->name ()); if (!info.destructible) error (_("expression cannot be evaluated because the type '%s' " "is not destructible"), param_type->name ()); if (info.trivially_copyable) continue; /* Make a copy of the argument on the stack. If the argument is trivially copy ctor'able, copy bit by bit. Otherwise, call the copy ctor to initialize the clone. */ CORE_ADDR addr = reserve_stack_space (param_type, sp); value *clone = value_from_contents_and_address (param_type, nullptr, addr); push_thread_stack_temporary (call_thread.get (), clone); value *clone_ptr = value_from_pointer (lookup_pointer_type (param_type), addr); if (info.trivially_copy_constructible) { int length = TYPE_LENGTH (param_type); write_memory (addr, value_contents (args[i]), length); } else { value *copy_ctor; value *cctor_args[2] = { clone_ptr, original_arg }; find_overload_match (gdb::make_array_view (cctor_args, 2), param_type->name (), METHOD, &clone_ptr, nullptr, ©_ctor, nullptr, nullptr, 0, EVAL_NORMAL); if (copy_ctor == nullptr) error (_("expression cannot be evaluated because a copy " "constructor for the type '%s' could not be found " "(maybe inlined?)"), param_type->name ()); call_function_by_hand (copy_ctor, default_return_type, gdb::make_array_view (cctor_args, 2)); } /* If the argument has a destructor, remember it so that we invoke it after the infcall is complete. */ if (!info.trivially_destructible) { /* Looking up the function via overload resolution does not work because the compiler (in particular, gcc) adds an artificial int parameter in some cases. So we look up the function by using the "~" name. This should be OK because there can be only one dtor definition. */ const char *dtor_name = nullptr; for (int fieldnum = 0; fieldnum < TYPE_NFN_FIELDS (param_type); fieldnum++) { fn_field *fn = TYPE_FN_FIELDLIST1 (param_type, fieldnum); const char *field_name = TYPE_FN_FIELDLIST_NAME (param_type, fieldnum); if (field_name[0] == '~') dtor_name = TYPE_FN_FIELD_PHYSNAME (fn, 0); } if (dtor_name == nullptr) error (_("expression cannot be evaluated because a destructor " "for the type '%s' could not be found " "(maybe inlined?)"), param_type->name ()); value *dtor = find_function_in_inferior (dtor_name, 0); /* Insert the dtor to the front of the list to call them in reverse order later. */ dtors_to_invoke.emplace_front (dtor, clone_ptr); } args[i] = clone_ptr; } /* Reserve space for the return structure to be written on the stack, if necessary. While evaluating expressions, we reserve space on the stack for return values of class type even if the language ABI and the target ABI do not require that the return value be passed as a hidden first argument. This is because we want to store the return value as an on-stack temporary while the expression is being evaluated. This enables us to have chained function calls in expressions. Keeping the return values as on-stack temporaries while the expression is being evaluated is OK because the thread is stopped until the expression is completely evaluated. */ if (return_method != return_method_normal || (stack_temporaries && class_or_union_p (values_type))) struct_addr = reserve_stack_space (values_type, sp); std::vector<struct value *> new_args; if (return_method == return_method_hidden_param) { /* Add the new argument to the front of the argument list. */ new_args.reserve (args.size ()); new_args.push_back (value_from_pointer (lookup_pointer_type (values_type), struct_addr)); new_args.insert (new_args.end (), args.begin (), args.end ()); args = new_args; } /* Create the dummy stack frame. Pass in the call dummy address as, presumably, the ABI code knows where, in the call dummy, the return address should be pointed. */ sp = gdbarch_push_dummy_call (gdbarch, function, get_current_regcache (), bp_addr, args.size (), args.data (), sp, return_method, struct_addr); /* Set up a frame ID for the dummy frame so we can pass it to set_momentary_breakpoint. We need to give the breakpoint a frame ID so that the breakpoint code can correctly re-identify the dummy breakpoint. */ /* Sanity. The exact same SP value is returned by PUSH_DUMMY_CALL, saved as the dummy-frame TOS, and used by dummy_id to form the frame ID's stack address. */ dummy_id = frame_id_build (sp, bp_addr); /* Create a momentary breakpoint at the return address of the inferior. That way it breaks when it returns. */ { symtab_and_line sal; sal.pspace = current_program_space; sal.pc = bp_addr; sal.section = find_pc_overlay (sal.pc); /* Sanity. The exact same SP value is returned by PUSH_DUMMY_CALL, saved as the dummy-frame TOS, and used by dummy_id to form the frame ID's stack address. */ breakpoint *bpt = set_momentary_breakpoint (gdbarch, sal, dummy_id, bp_call_dummy).release (); /* set_momentary_breakpoint invalidates FRAME. */ frame = NULL; bpt->disposition = disp_del; gdb_assert (bpt->related_breakpoint == bpt); breakpoint *longjmp_b = set_longjmp_breakpoint_for_call_dummy (); if (longjmp_b) { /* Link BPT into the chain of LONGJMP_B. */ bpt->related_breakpoint = longjmp_b; while (longjmp_b->related_breakpoint != bpt->related_breakpoint) longjmp_b = longjmp_b->related_breakpoint; longjmp_b->related_breakpoint = bpt; } } /* Create a breakpoint in std::terminate. If a C++ exception is raised in the dummy-frame, and the exception handler is (normally, and expected to be) out-of-frame, the default C++ handler will (wrongly) be called in an inferior function call. This is wrong, as an exception can be normally and legally handled out-of-frame. The confines of the dummy frame prevent the unwinder from finding the correct handler (or any handler, unless it is in-frame). The default handler calls std::terminate. This will kill the inferior. Assert that terminate should never be called in an inferior function call. Place a momentary breakpoint in the std::terminate function and if triggered in the call, rewind. */ if (unwind_on_terminating_exception_p) set_std_terminate_breakpoint (); /* Everything's ready, push all the info needed to restore the caller (and identify the dummy-frame) onto the dummy-frame stack. */ dummy_frame_push (caller_state.release (), &dummy_id, call_thread.get ()); if (dummy_dtor != NULL) register_dummy_frame_dtor (dummy_id, call_thread.get (), dummy_dtor, dummy_dtor_data); /* Register a clean-up for unwind_on_terminating_exception_breakpoint. */ SCOPE_EXIT { delete_std_terminate_breakpoint (); }; /* - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP - If you're looking to implement asynchronous dummy-frames, then just below is the place to chop this function in two.. */ { struct thread_fsm *saved_sm; struct call_thread_fsm *sm; /* Save the current FSM. We'll override it. */ saved_sm = call_thread->thread_fsm; call_thread->thread_fsm = NULL; /* Save this thread's ptid, we need it later but the thread may have exited. */ call_thread_ptid = call_thread->ptid; /* Run the inferior until it stops. */ /* Create the FSM used to manage the infcall. It tells infrun to not report the stop to the user, and captures the return value before the dummy frame is popped. run_inferior_call registers it with the thread ASAP. */ sm = new call_thread_fsm (current_ui, command_interp (), gdbarch, function, values_type, return_method != return_method_normal, struct_addr); e = run_inferior_call (sm, call_thread.get (), real_pc); gdb::observers::inferior_call_post.notify (call_thread_ptid, funaddr); if (call_thread->state != THREAD_EXITED) { /* The FSM should still be the same. */ gdb_assert (call_thread->thread_fsm == sm); if (call_thread->thread_fsm->finished_p ()) { struct value *retval; /* The inferior call is successful. Pop the dummy frame, which runs its destructors and restores the inferior's suspend state, and restore the inferior control state. */ dummy_frame_pop (dummy_id, call_thread.get ()); restore_infcall_control_state (inf_status.release ()); /* Get the return value. */ retval = sm->return_value; /* Clean up / destroy the call FSM, and restore the original one. */ call_thread->thread_fsm->clean_up (call_thread.get ()); delete call_thread->thread_fsm; call_thread->thread_fsm = saved_sm; maybe_remove_breakpoints (); gdb_assert (retval != NULL); /* Destruct the pass-by-ref argument clones. */ call_destructors (dtors_to_invoke, default_return_type); return retval; } /* Didn't complete. Clean up / destroy the call FSM, and restore the previous state machine, and handle the error. */ call_thread->thread_fsm->clean_up (call_thread.get ()); delete call_thread->thread_fsm; call_thread->thread_fsm = saved_sm; } } /* Rethrow an error if we got one trying to run the inferior. */ if (e.reason < 0) { const char *name = get_function_name (funaddr, name_buf, sizeof (name_buf)); discard_infcall_control_state (inf_status.release ()); /* We could discard the dummy frame here if the program exited, but it will get garbage collected the next time the program is run anyway. */ switch (e.reason) { case RETURN_ERROR: throw_error (e.error, _("%s\n\ An error occurred while in a function called from GDB.\n\ Evaluation of the expression containing the function\n\ (%s) will be abandoned.\n\ When the function is done executing, GDB will silently stop."), e.what (), name); case RETURN_QUIT: default: throw_exception (std::move (e)); } } /* If the program has exited, or we stopped at a different thread, exit and inform the user. */ if (! target_has_execution ()) { const char *name = get_function_name (funaddr, name_buf, sizeof (name_buf)); /* If we try to restore the inferior status, we'll crash as the inferior is no longer running. */ discard_infcall_control_state (inf_status.release ()); /* We could discard the dummy frame here given that the program exited, but it will get garbage collected the next time the program is run anyway. */ error (_("The program being debugged exited while in a function " "called from GDB.\n" "Evaluation of the expression containing the function\n" "(%s) will be abandoned."), name); } if (call_thread_ptid != inferior_ptid) { const char *name = get_function_name (funaddr, name_buf, sizeof (name_buf)); /* We've switched threads. This can happen if another thread gets a signal or breakpoint while our thread was running. There's no point in restoring the inferior status, we're in a different thread. */ discard_infcall_control_state (inf_status.release ()); /* Keep the dummy frame record, if the user switches back to the thread with the hand-call, we'll need it. */ if (stopped_by_random_signal) error (_("\ The program received a signal in another thread while\n\ making a function call from GDB.\n\ Evaluation of the expression containing the function\n\ (%s) will be abandoned.\n\ When the function is done executing, GDB will silently stop."), name); else error (_("\ The program stopped in another thread while making a function call from GDB.\n\ Evaluation of the expression containing the function\n\ (%s) will be abandoned.\n\ When the function is done executing, GDB will silently stop."), name); } { /* Make a copy as NAME may be in an objfile freed by dummy_frame_pop. */ std::string name = get_function_name (funaddr, name_buf, sizeof (name_buf)); if (stopped_by_random_signal) { /* We stopped inside the FUNCTION because of a random signal. Further execution of the FUNCTION is not allowed. */ if (unwind_on_signal_p) { /* The user wants the context restored. */ /* We must get back to the frame we were before the dummy call. */ dummy_frame_pop (dummy_id, call_thread.get ()); /* We also need to restore inferior status to that before the dummy call. */ restore_infcall_control_state (inf_status.release ()); /* FIXME: Insert a bunch of wrap_here; name can be very long if it's a C++ name with arguments and stuff. */ error (_("\ The program being debugged was signaled while in a function called from GDB.\n\ GDB has restored the context to what it was before the call.\n\ To change this behavior use \"set unwindonsignal off\".\n\ Evaluation of the expression containing the function\n\ (%s) will be abandoned."), name.c_str ()); } else { /* The user wants to stay in the frame where we stopped (default). Discard inferior status, we're not at the same point we started at. */ discard_infcall_control_state (inf_status.release ()); /* FIXME: Insert a bunch of wrap_here; name can be very long if it's a C++ name with arguments and stuff. */ error (_("\ The program being debugged was signaled while in a function called from GDB.\n\ GDB remains in the frame where the signal was received.\n\ To change this behavior use \"set unwindonsignal on\".\n\ Evaluation of the expression containing the function\n\ (%s) will be abandoned.\n\ When the function is done executing, GDB will silently stop."), name.c_str ()); } } if (stop_stack_dummy == STOP_STD_TERMINATE) { /* We must get back to the frame we were before the dummy call. */ dummy_frame_pop (dummy_id, call_thread.get ()); /* We also need to restore inferior status to that before the dummy call. */ restore_infcall_control_state (inf_status.release ()); error (_("\ The program being debugged entered a std::terminate call, most likely\n\ caused by an unhandled C++ exception. GDB blocked this call in order\n\ to prevent the program from being terminated, and has restored the\n\ context to its original state before the call.\n\ To change this behaviour use \"set unwind-on-terminating-exception off\".\n\ Evaluation of the expression containing the function (%s)\n\ will be abandoned."), name.c_str ()); } else if (stop_stack_dummy == STOP_NONE) { /* We hit a breakpoint inside the FUNCTION. Keep the dummy frame, the user may want to examine its state. Discard inferior status, we're not at the same point we started at. */ discard_infcall_control_state (inf_status.release ()); /* The following error message used to say "The expression which contained the function call has been discarded." It is a hard concept to explain in a few words. Ideally, GDB would be able to resume evaluation of the expression when the function finally is done executing. Perhaps someday this will be implemented (it would not be easy). */ /* FIXME: Insert a bunch of wrap_here; name can be very long if it's a C++ name with arguments and stuff. */ error (_("\ The program being debugged stopped while in a function called from GDB.\n\ Evaluation of the expression containing the function\n\ (%s) will be abandoned.\n\ When the function is done executing, GDB will silently stop."), name.c_str ()); } } /* The above code errors out, so ... */ gdb_assert_not_reached ("... should not be here"); } void _initialize_infcall (); void _initialize_infcall () { add_setshow_boolean_cmd ("may-call-functions", no_class, &may_call_functions_p, _("\ Set permission to call functions in the program."), _("\ Show permission to call functions in the program."), _("\ When this permission is on, GDB may call functions in the program.\n\ Otherwise, any sort of attempt to call a function in the program\n\ will result in an error."), NULL, show_may_call_functions_p, &setlist, &showlist); add_setshow_boolean_cmd ("coerce-float-to-double", class_obscure, &coerce_float_to_double_p, _("\ Set coercion of floats to doubles when calling functions."), _("\ Show coercion of floats to doubles when calling functions."), _("\ Variables of type float should generally be converted to doubles before\n\ calling an unprototyped function, and left alone when calling a prototyped\n\ function. However, some older debug info formats do not provide enough\n\ information to determine that a function is prototyped. If this flag is\n\ set, GDB will perform the conversion for a function it considers\n\ unprototyped.\n\ The default is to perform the conversion."), NULL, show_coerce_float_to_double_p, &setlist, &showlist); add_setshow_boolean_cmd ("unwindonsignal", no_class, &unwind_on_signal_p, _("\ Set unwinding of stack if a signal is received while in a call dummy."), _("\ Show unwinding of stack if a signal is received while in a call dummy."), _("\ The unwindonsignal lets the user determine what gdb should do if a signal\n\ is received while in a function called from gdb (call dummy). If set, gdb\n\ unwinds the stack and restore the context to what as it was before the call.\n\ The default is to stop in the frame where the signal was received."), NULL, show_unwind_on_signal_p, &setlist, &showlist); add_setshow_boolean_cmd ("unwind-on-terminating-exception", no_class, &unwind_on_terminating_exception_p, _("\ Set unwinding of stack if std::terminate is called while in call dummy."), _("\ Show unwinding of stack if std::terminate() is called while in a call dummy."), _("\ The unwind on terminating exception flag lets the user determine\n\ what gdb should do if a std::terminate() call is made from the\n\ default exception handler. If set, gdb unwinds the stack and restores\n\ the context to what it was before the call. If unset, gdb allows the\n\ std::terminate call to proceed.\n\ The default is to unwind the frame."), NULL, show_unwind_on_terminating_exception_p, &setlist, &showlist); }