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