/* Code dealing with dummy stack frames, for GDB, the GNU debugger. Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002 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 2 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, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #include "defs.h" #include "dummy-frame.h" #include "regcache.h" #include "frame.h" #include "inferior.h" #include "gdb_assert.h" #include "frame-unwind.h" #include "command.h" #include "gdbcmd.h" static void dummy_frame_this_id (struct frame_info *next_frame, void **this_prologue_cache, struct frame_id *this_id); /* Dummy frame. This saves the processor state just prior to setting up the inferior function call. Older targets save the registers on the target stack (but that really slows down function calls). */ struct dummy_frame { struct dummy_frame *next; /* These values belong to the caller (the previous frame, the frame that this unwinds back to). */ CORE_ADDR pc; CORE_ADDR fp; CORE_ADDR sp; CORE_ADDR top; struct frame_id id; struct regcache *regcache; /* Address range of the call dummy code. Look for PC in the range [LO..HI) (after allowing for DECR_PC_AFTER_BREAK). */ CORE_ADDR call_lo; CORE_ADDR call_hi; /* APPLE LOCAL: The thread on whose stack we are running this frame. */ struct ptid ptid; }; static struct dummy_frame *dummy_frame_stack = NULL; /* Function: find_dummy_frame(pc, fp, sp) Search the stack of dummy frames for one matching the given PC and FP/SP. Unlike pc_in_dummy_frame(), this function doesn't need to adjust for DECR_PC_AFTER_BREAK. This is because it is only legal to call this function after the PC has been adjusted. */ static struct dummy_frame * find_dummy_frame (CORE_ADDR pc, CORE_ADDR fp) { struct dummy_frame *dummyframe; for (dummyframe = dummy_frame_stack; dummyframe != NULL; dummyframe = dummyframe->next) { /* APPLE LOCAL: does the ptid match? */ if (!ptid_equal (dummyframe->ptid, inferior_ptid)) continue; /* Does the PC fall within the dummy frame's breakpoint instruction. If not, discard this one. */ if (!(pc >= dummyframe->call_lo && pc < dummyframe->call_hi)) continue; /* Does the FP match? */ if (dummyframe->top != 0) { /* If the target architecture explicitly saved the top-of-stack before the inferior function call, assume that that same architecture will always pass in an FP (frame base) value that eactly matches that saved TOS. Don't check the saved SP and SP as they can lead to false hits. */ if (fp != dummyframe->top) continue; } else { /* An older target that hasn't explicitly or implicitly saved the dummy frame's top-of-stack. Try matching the FP against the saved SP and FP. NOTE: If you're trying to fix a problem with GDB not correctly finding a dummy frame, check the comments that go with FRAME_ALIGN() and UNWIND_DUMMY_ID(). */ if (fp != dummyframe->fp && fp != dummyframe->sp) continue; } /* The FP matches this dummy frame. */ return dummyframe; } return NULL; } struct regcache * deprecated_find_dummy_frame_regcache (CORE_ADDR pc, CORE_ADDR fp) { struct dummy_frame *dummy = find_dummy_frame (pc, fp); if (dummy != NULL) return dummy->regcache; else return NULL; } char * deprecated_generic_find_dummy_frame (CORE_ADDR pc, CORE_ADDR fp) { struct regcache *regcache = deprecated_find_dummy_frame_regcache (pc, fp); if (regcache == NULL) return NULL; return deprecated_grub_regcache_for_registers (regcache); } /* Function: pc_in_call_dummy (pc, sp, fp) Return true if the PC falls in a dummy frame created by gdb for an inferior call. The code below which allows DECR_PC_AFTER_BREAK is for infrun.c, which may give the function a PC without that subtracted out. */ int generic_pc_in_call_dummy (CORE_ADDR pc, CORE_ADDR sp, CORE_ADDR fp) { return pc_in_dummy_frame (pc); } /* Return non-zero if the PC falls in a dummy frame. The code below which allows DECR_PC_AFTER_BREAK is for infrun.c, which may give the function a PC without that subtracted out. FIXME: cagney/2002-11-23: This is silly. Surely "infrun.c" can figure out what the real PC (as in the resume address) is BEFORE calling this function (Oh, and I'm not even sure that this function is called with an decremented PC, the call to pc_in_call_dummy() in that file is conditional on !DEPRECATED_CALL_DUMMY_BREAKPOINT_OFFSET_P yet generic dummy targets set DEPRECATED_CALL_DUMMY_BREAKPOINT_OFFSET. True?). */ int pc_in_dummy_frame (CORE_ADDR pc) { struct dummy_frame *dummyframe; for (dummyframe = dummy_frame_stack; dummyframe != NULL; dummyframe = dummyframe->next) { /* APPLE LOCAL: Check the ptid here as well as the address. */ if (ptid_equal (dummyframe->ptid, inferior_ptid) && (pc >= dummyframe->call_lo) && (pc < dummyframe->call_hi + DECR_PC_AFTER_BREAK)) return 1; } return 0; } /* Function: read_register_dummy Find a saved register from before GDB calls a function in the inferior */ CORE_ADDR deprecated_read_register_dummy (CORE_ADDR pc, CORE_ADDR fp, int regno) { struct regcache *dummy_regs = deprecated_find_dummy_frame_regcache (pc, fp); if (dummy_regs) { /* NOTE: cagney/2002-08-12: Replaced a call to regcache_raw_read_as_address() with a call to regcache_cooked_read_unsigned(). The old, ...as_address function was eventually calling extract_unsigned_integer (nee extract_address) to unpack the registers value. The below is doing an unsigned extract so that it is functionally equivalent. The read needs to be cooked as, otherwise, it will never correctly return the value of a register in the [NUM_REGS .. NUM_REGS+NUM_PSEUDO_REGS) range. */ ULONGEST val; regcache_cooked_read_unsigned (dummy_regs, regno, &val); return val; } else return 0; } /* Save all the registers on the dummy frame stack. Most ports save the registers on the target stack. This results in lots of unnecessary memory references, which are slow when debugging via a serial line. Instead, we save all the registers internally, and never write them to the stack. The registers get restored when the called function returns to the entry point, where a breakpoint is laying in wait. */ void generic_push_dummy_frame (void) { struct dummy_frame *dummy_frame; CORE_ADDR fp = get_frame_base (get_current_frame ()); /* check to see if there are stale dummy frames, perhaps left over from when a longjump took us out of a function that was called by the debugger */ dummy_frame = dummy_frame_stack; while (dummy_frame) /* APPLE LOCAL: Check the ptid as well as the frame. */ if (ptid_equal (dummy_frame->ptid, inferior_ptid) && INNER_THAN (dummy_frame->fp, fp)) /* stale -- destroy! */ { dummy_frame_stack = dummy_frame->next; regcache_xfree (dummy_frame->regcache); xfree (dummy_frame); dummy_frame = dummy_frame_stack; } else dummy_frame = dummy_frame->next; dummy_frame = xmalloc (sizeof (struct dummy_frame)); dummy_frame->regcache = regcache_xmalloc (current_gdbarch); dummy_frame->pc = read_pc (); dummy_frame->sp = read_sp (); dummy_frame->top = 0; dummy_frame->fp = fp; dummy_frame->id = get_frame_id (get_current_frame ()); regcache_cpy (dummy_frame->regcache, current_regcache); /* APPLE LOCAL: Initialize this frames ptid. */ dummy_frame->ptid = inferior_ptid; dummy_frame->next = dummy_frame_stack; dummy_frame_stack = dummy_frame; } void generic_save_dummy_frame_tos (CORE_ADDR sp) { dummy_frame_stack->top = sp; } /* Record the upper/lower bounds on the address of the call dummy. */ void generic_save_call_dummy_addr (CORE_ADDR lo, CORE_ADDR hi) { dummy_frame_stack->call_lo = lo; dummy_frame_stack->call_hi = hi; } /* Restore the machine state from either the saved dummy stack or a real stack frame. */ void generic_pop_current_frame (void (*popper) (struct frame_info * frame)) { struct frame_info *frame = get_current_frame (); if (get_frame_type (frame) == DUMMY_FRAME) /* NOTE: cagney/2002-22-23: Does this ever occure? Surely a dummy frame will have already been poped by the "infrun.c" code. */ generic_pop_dummy_frame (); else (*popper) (frame); } /* Discard the innermost dummy frame from the dummy frame stack APPLE LOCAL: Also pass in a dummy_ptid so we can restrict out attention to only the current thread. */ static int discard_innermost_dummy (struct dummy_frame **stack, struct ptid dummy_ptid) { struct dummy_frame *tbd = (*stack); struct dummy_frame *prev = (*stack); while (!ptid_equal (tbd->ptid, dummy_ptid)) { prev = tbd; tbd = tbd->next; if (tbd == NULL) { fprintf_unfiltered (gdb_stderr, "No dummy frame to push for the current thread\n"); return 0; } } if (tbd == *stack) (*stack) = (*stack)->next; else prev->next = tbd->next; regcache_xfree (tbd->regcache); xfree (tbd); return 1; } void generic_pop_dummy_frame (void) { struct dummy_frame *dummy_frame = dummy_frame_stack; /* FIXME: what if the first frame isn't the right one, eg.. because one call-by-hand function has done a longjmp into another one? */ if (!dummy_frame) error ("Can't pop dummy frame!"); regcache_cpy (current_regcache, dummy_frame->regcache); flush_cached_frames (); /* APPLE LOCAL: Pass in the current thread as well. */ discard_innermost_dummy (&dummy_frame_stack, inferior_ptid); } /* Given a call-dummy dummy-frame, return the registers. Here the register value is taken from the local copy of the register buffer. */ static void dummy_frame_prev_register (struct frame_info *next_frame, void **this_prologue_cache, int regnum, int *optimized, enum lval_type *lvalp, CORE_ADDR *addrp, int *realnum, void *bufferp) { struct dummy_frame *dummy; struct frame_id id; /* Call the ID method which, if at all possible, will set the prologue cache. */ dummy_frame_this_id (next_frame, this_prologue_cache, &id); dummy = (*this_prologue_cache); gdb_assert (dummy != NULL); /* Describe the register's location. Generic dummy frames always have the register value in an ``expression''. */ *optimized = 0; *lvalp = not_lval; *addrp = 0; *realnum = -1; /* If needed, find and return the value of the register. */ if (bufferp != NULL) { /* Return the actual value. */ /* Use the regcache_cooked_read() method so that it, on the fly, constructs either a raw or pseudo register from the raw register cache. */ regcache_cooked_read (dummy->regcache, regnum, bufferp); } } /* Assuming that THIS frame is a dummy (remember, the NEXT and not THIS frame is passed in), return the ID of THIS frame. That ID is determined by examining the NEXT frame's unwound registers using the method unwind_dummy_id(). As a side effect, THIS dummy frame's dummy cache is located and and saved in THIS_PROLOGUE_CACHE. */ static void dummy_frame_this_id (struct frame_info *next_frame, void **this_prologue_cache, struct frame_id *this_id) { struct dummy_frame *dummy = (*this_prologue_cache); if (dummy != NULL) { (*this_id) = dummy->id; return; } /* When unwinding a normal frame, the stack structure is determined by analyzing the frame's function's code (be it using brute force prologue analysis, or the dwarf2 CFI). In the case of a dummy frame, that simply isn't possible. The The PC is either the program entry point, or some random address on the stack. Trying to use that PC to apply standard frame ID unwind techniques is just asking for trouble. */ if (gdbarch_unwind_dummy_id_p (current_gdbarch)) { /* Use an architecture specific method to extract the prev's dummy ID from the next frame. Note that this method uses frame_register_unwind to obtain the register values needed to determine the dummy frame's ID. */ (*this_id) = gdbarch_unwind_dummy_id (current_gdbarch, next_frame); } else if (frame_relative_level (next_frame) < 0) { /* We're unwinding a sentinel frame, the PC of which is pointing at a stack dummy. Fake up the dummy frame's ID using the same sequence as is found a traditional unwinder. Once all architectures supply the unwind_dummy_id method, this code can go away. */ (*this_id) = frame_id_build (deprecated_read_fp (), read_pc ()); } else if (legacy_frame_p (current_gdbarch) && get_prev_frame (next_frame)) { /* Things are looking seriously grim! Assume that the legacy get_prev_frame code has already created THIS frame and linked it in to the frame chain (a pretty bold assumption), extract the ID from THIS base / pc. */ (*this_id) = frame_id_build (get_frame_base (get_prev_frame (next_frame)), get_frame_pc (get_prev_frame (next_frame))); } else { /* Ouch! We're not trying to find the innermost frame's ID yet we're trying to unwind to a dummy. The architecture must provide the unwind_dummy_id() method. Abandon the unwind process but only after first warning the user. */ internal_warning (__FILE__, __LINE__, "Missing unwind_dummy_id architecture method"); (*this_id) = null_frame_id; return; } (*this_prologue_cache) = find_dummy_frame ((*this_id).code_addr, (*this_id).stack_addr); } static struct frame_unwind dummy_frame_unwind = { DUMMY_FRAME, dummy_frame_this_id, dummy_frame_prev_register }; const struct frame_unwind * dummy_frame_sniffer (struct frame_info *next_frame) { CORE_ADDR pc = frame_pc_unwind (next_frame); if (DEPRECATED_PC_IN_CALL_DUMMY_P () ? DEPRECATED_PC_IN_CALL_DUMMY (pc, 0, 0) : pc_in_dummy_frame (pc)) return &dummy_frame_unwind; else return NULL; } static void fprint_dummy_frames (struct ui_file *file) { struct dummy_frame *s; for (s = dummy_frame_stack; s != NULL; s = s->next) { gdb_print_host_address (s, file); fprintf_unfiltered (file, ":"); fprintf_unfiltered (file, " pc=0x%s", paddr (s->pc)); fprintf_unfiltered (file, " fp=0x%s", paddr (s->fp)); fprintf_unfiltered (file, " sp=0x%s", paddr (s->sp)); fprintf_unfiltered (file, " top=0x%s", paddr (s->top)); fprintf_unfiltered (file, " id="); fprint_frame_id (file, s->id); fprintf_unfiltered (file, " call_lo=0x%s", paddr (s->call_lo)); fprintf_unfiltered (file, " call_hi=0x%s", paddr (s->call_hi)); fprintf_unfiltered (file, "\n"); } } static void maintenance_print_dummy_frames (char *args, int from_tty) { if (args == NULL) fprint_dummy_frames (gdb_stdout); else { struct ui_file *file = gdb_fopen (args, "w"); if (file == NULL) perror_with_name ("maintenance print dummy-frames"); fprint_dummy_frames (file); ui_file_delete (file); } } extern void _initialize_dummy_frame (void); void _initialize_dummy_frame (void) { add_cmd ("dummy-frames", class_maintenance, maintenance_print_dummy_frames, "Print the contents of the internal dummy-frame stack.", &maintenanceprintlist); }