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binutils-gdb/gdb/frame.c

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/* Cache and manage frames for GDB, the GNU debugger.
Copyright 1986, 1987, 1989, 1991, 1994, 1995, 1996, 1998, 2000,
2001, 2002, 2003, 2004 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 "frame.h"
#include "target.h"
#include "value.h"
#include "inferior.h" /* for inferior_ptid */
#include "regcache.h"
#include "gdb_assert.h"
#include "gdb_string.h"
#include "user-regs.h"
#include "gdb_obstack.h"
#include "dummy-frame.h"
#include "sentinel-frame.h"
#include "gdbcore.h"
#include "annotate.h"
#include "language.h"
#include "frame-unwind.h"
#include "frame-base.h"
#include "command.h"
#include "gdbcmd.h"
#include "observer.h"
#include "objfiles.h"
static struct frame_info *get_prev_frame_1 (struct frame_info *this_frame);
/* We keep a cache of stack frames, each of which is a "struct
frame_info". The innermost one gets allocated (in
wait_for_inferior) each time the inferior stops; current_frame
points to it. Additional frames get allocated (in get_prev_frame)
as needed, and are chained through the next and prev fields. Any
time that the frame cache becomes invalid (most notably when we
execute something, but also if we change how we interpret the
frames (e.g. "set heuristic-fence-post" in mips-tdep.c, or anything
which reads new symbols)), we should call reinit_frame_cache. */
struct frame_info
{
/* Level of this frame. The inner-most (youngest) frame is at level
0. As you move towards the outer-most (oldest) frame, the level
increases. This is a cached value. It could just as easily be
computed by counting back from the selected frame to the inner
most frame. */
/* NOTE: cagney/2002-04-05: Perhaps a level of ``-1'' should be
reserved to indicate a bogus frame - one that has been created
just to keep GDB happy (GDB always needs a frame). For the
moment leave this as speculation. */
int level;
/* The frame's low-level unwinder and corresponding cache. The
low-level unwinder is responsible for unwinding register values
for the previous frame. The low-level unwind methods are
selected based on the presence, or otherwise, of register unwind
information such as CFI. */
void *prologue_cache;
const struct frame_unwind *unwind;
/* Cached copy of the previous frame's resume address. */
struct {
int p;
CORE_ADDR value;
} prev_pc;
/* Cached copy of the previous frame's function address. */
struct
{
CORE_ADDR addr;
int p;
} prev_func;
/* This frame's ID. */
struct
{
int p;
struct frame_id value;
} this_id;
/* The frame's high-level base methods, and corresponding cache.
The high level base methods are selected based on the frame's
debug info. */
const struct frame_base *base;
void *base_cache;
/* Pointers to the next (down, inner, younger) and previous (up,
outer, older) frame_info's in the frame cache. */
struct frame_info *next; /* down, inner, younger */
int prev_p;
struct frame_info *prev; /* up, outer, older */
};
/* Flag to control debugging. */
static int frame_debug;
/* Flag to indicate whether backtraces should stop at main et.al. */
static int backtrace_past_main;
static unsigned int backtrace_limit = UINT_MAX;
static void
fprint_field (struct ui_file *file, const char *name, int p, CORE_ADDR addr)
{
if (p)
fprintf_unfiltered (file, "%s=0x%s", name, paddr_nz (addr));
else
fprintf_unfiltered (file, "!%s", name);
}
void
fprint_frame_id (struct ui_file *file, struct frame_id id)
{
fprintf_unfiltered (file, "{");
fprint_field (file, "stack", id.stack_addr_p, id.stack_addr);
fprintf_unfiltered (file, ",");
fprint_field (file, "code", id.code_addr_p, id.code_addr);
fprintf_unfiltered (file, ",");
fprint_field (file, "special", id.special_addr_p, id.special_addr);
fprintf_unfiltered (file, "}");
}
static void
fprint_frame_type (struct ui_file *file, enum frame_type type)
{
switch (type)
{
case NORMAL_FRAME:
fprintf_unfiltered (file, "NORMAL_FRAME");
return;
case DUMMY_FRAME:
fprintf_unfiltered (file, "DUMMY_FRAME");
return;
case SIGTRAMP_FRAME:
fprintf_unfiltered (file, "SIGTRAMP_FRAME");
return;
default:
fprintf_unfiltered (file, "<unknown type>");
return;
};
}
static void
fprint_frame (struct ui_file *file, struct frame_info *fi)
{
if (fi == NULL)
{
fprintf_unfiltered (file, "<NULL frame>");
return;
}
fprintf_unfiltered (file, "{");
fprintf_unfiltered (file, "level=%d", fi->level);
fprintf_unfiltered (file, ",");
fprintf_unfiltered (file, "type=");
if (fi->unwind != NULL)
fprint_frame_type (file, fi->unwind->type);
else
fprintf_unfiltered (file, "<unknown>");
fprintf_unfiltered (file, ",");
fprintf_unfiltered (file, "unwind=");
if (fi->unwind != NULL)
gdb_print_host_address (fi->unwind, file);
else
fprintf_unfiltered (file, "<unknown>");
fprintf_unfiltered (file, ",");
fprintf_unfiltered (file, "pc=");
if (fi->next != NULL && fi->next->prev_pc.p)
fprintf_unfiltered (file, "0x%s", paddr_nz (fi->next->prev_pc.value));
else
fprintf_unfiltered (file, "<unknown>");
fprintf_unfiltered (file, ",");
fprintf_unfiltered (file, "id=");
if (fi->this_id.p)
fprint_frame_id (file, fi->this_id.value);
else
fprintf_unfiltered (file, "<unknown>");
fprintf_unfiltered (file, ",");
fprintf_unfiltered (file, "func=");
if (fi->next != NULL && fi->next->prev_func.p)
fprintf_unfiltered (file, "0x%s", paddr_nz (fi->next->prev_func.addr));
else
fprintf_unfiltered (file, "<unknown>");
fprintf_unfiltered (file, "}");
}
/* Return a frame uniq ID that can be used to, later, re-find the
frame. */
struct frame_id
get_frame_id (struct frame_info *fi)
{
if (fi == NULL)
{
return null_frame_id;
}
if (!fi->this_id.p)
{
if (frame_debug)
fprintf_unfiltered (gdb_stdlog, "{ get_frame_id (fi=%d) ",
fi->level);
/* Find the unwinder. */
if (fi->unwind == NULL)
fi->unwind = frame_unwind_find_by_frame (fi->next,
&fi->prologue_cache);
/* Find THIS frame's ID. */
fi->unwind->this_id (fi->next, &fi->prologue_cache, &fi->this_id.value);
fi->this_id.p = 1;
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame_id (gdb_stdlog, fi->this_id.value);
fprintf_unfiltered (gdb_stdlog, " }\n");
}
}
return fi->this_id.value;
}
struct frame_id
frame_unwind_id (struct frame_info *next_frame)
{
/* Use prev_frame, and not get_prev_frame. The latter will truncate
the frame chain, leading to this function unintentionally
returning a null_frame_id (e.g., when a caller requests the frame
ID of "main()"s caller. */
return get_frame_id (get_prev_frame_1 (next_frame));
}
const struct frame_id null_frame_id; /* All zeros. */
struct frame_id
frame_id_build_special (CORE_ADDR stack_addr, CORE_ADDR code_addr,
CORE_ADDR special_addr)
{
struct frame_id id = null_frame_id;
id.stack_addr = stack_addr;
id.stack_addr_p = 1;
id.code_addr = code_addr;
id.code_addr_p = 1;
id.special_addr = special_addr;
id.special_addr_p = 1;
return id;
}
struct frame_id
frame_id_build (CORE_ADDR stack_addr, CORE_ADDR code_addr)
{
struct frame_id id = null_frame_id;
id.stack_addr = stack_addr;
id.stack_addr_p = 1;
id.code_addr = code_addr;
id.code_addr_p = 1;
return id;
}
struct frame_id
frame_id_build_wild (CORE_ADDR stack_addr)
{
struct frame_id id = null_frame_id;
id.stack_addr = stack_addr;
id.stack_addr_p = 1;
return id;
}
int
frame_id_p (struct frame_id l)
{
int p;
/* The frame is valid iff it has a valid stack address. */
p = l.stack_addr_p;
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "{ frame_id_p (l=");
fprint_frame_id (gdb_stdlog, l);
fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", p);
}
return p;
}
int
frame_id_eq (struct frame_id l, struct frame_id r)
{
int eq;
if (!l.stack_addr_p || !r.stack_addr_p)
/* Like a NaN, if either ID is invalid, the result is false.
Note that a frame ID is invalid iff it is the null frame ID. */
eq = 0;
else if (l.stack_addr != r.stack_addr)
/* If .stack addresses are different, the frames are different. */
eq = 0;
else if (!l.code_addr_p || !r.code_addr_p)
/* An invalid code addr is a wild card, always succeed. */
eq = 1;
else if (l.code_addr != r.code_addr)
/* If .code addresses are different, the frames are different. */
eq = 0;
else if (!l.special_addr_p || !r.special_addr_p)
/* An invalid special addr is a wild card (or unused), always succeed. */
eq = 1;
else if (l.special_addr == r.special_addr)
/* Frames are equal. */
eq = 1;
else
/* No luck. */
eq = 0;
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "{ frame_id_eq (l=");
fprint_frame_id (gdb_stdlog, l);
fprintf_unfiltered (gdb_stdlog, ",r=");
fprint_frame_id (gdb_stdlog, r);
fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", eq);
}
return eq;
}
int
frame_id_inner (struct frame_id l, struct frame_id r)
{
int inner;
if (!l.stack_addr_p || !r.stack_addr_p)
/* Like NaN, any operation involving an invalid ID always fails. */
inner = 0;
else
/* Only return non-zero when strictly inner than. Note that, per
comment in "frame.h", there is some fuzz here. Frameless
functions are not strictly inner than (same .stack but
different .code and/or .special address). */
inner = INNER_THAN (l.stack_addr, r.stack_addr);
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "{ frame_id_inner (l=");
fprint_frame_id (gdb_stdlog, l);
fprintf_unfiltered (gdb_stdlog, ",r=");
fprint_frame_id (gdb_stdlog, r);
fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", inner);
}
return inner;
}
struct frame_info *
frame_find_by_id (struct frame_id id)
{
struct frame_info *frame;
/* ZERO denotes the null frame, let the caller decide what to do
about it. Should it instead return get_current_frame()? */
if (!frame_id_p (id))
return NULL;
for (frame = get_current_frame ();
frame != NULL;
frame = get_prev_frame (frame))
{
struct frame_id this = get_frame_id (frame);
if (frame_id_eq (id, this))
/* An exact match. */
return frame;
if (frame_id_inner (id, this))
/* Gone to far. */
return NULL;
/* Either we're not yet gone far enough out along the frame
chain (inner(this,id)), or we're comparing frameless functions
(same .base, different .func, no test available). Struggle
on until we've definitly gone to far. */
}
return NULL;
}
CORE_ADDR
frame_pc_unwind (struct frame_info *this_frame)
{
if (!this_frame->prev_pc.p)
{
CORE_ADDR pc;
if (gdbarch_unwind_pc_p (current_gdbarch))
{
/* The right way. The `pure' way. The one true way. This
method depends solely on the register-unwind code to
determine the value of registers in THIS frame, and hence
the value of this frame's PC (resume address). A typical
implementation is no more than:
frame_unwind_register (this_frame, ISA_PC_REGNUM, buf);
return extract_unsigned_integer (buf, size of ISA_PC_REGNUM);
Note: this method is very heavily dependent on a correct
register-unwind implementation, it pays to fix that
method first; this method is frame type agnostic, since
it only deals with register values, it works with any
frame. This is all in stark contrast to the old
FRAME_SAVED_PC which would try to directly handle all the
different ways that a PC could be unwound. */
pc = gdbarch_unwind_pc (current_gdbarch, this_frame);
}
else if (this_frame->level < 0)
{
/* FIXME: cagney/2003-03-06: Old code and a sentinel
frame. Do like was always done. Fetch the PC's value
directly from the global registers array (via read_pc).
This assumes that this frame belongs to the current
global register cache. The assumption is dangerous. */
pc = read_pc ();
}
else
internal_error (__FILE__, __LINE__, "No gdbarch_unwind_pc method");
this_frame->prev_pc.value = pc;
this_frame->prev_pc.p = 1;
if (frame_debug)
fprintf_unfiltered (gdb_stdlog,
"{ frame_pc_unwind (this_frame=%d) -> 0x%s }\n",
this_frame->level,
paddr_nz (this_frame->prev_pc.value));
}
return this_frame->prev_pc.value;
}
CORE_ADDR
frame_func_unwind (struct frame_info *fi)
{
if (!fi->prev_func.p)
{
/* Make certain that this, and not the adjacent, function is
found. */
CORE_ADDR addr_in_block = frame_unwind_address_in_block (fi);
fi->prev_func.p = 1;
fi->prev_func.addr = get_pc_function_start (addr_in_block);
if (frame_debug)
fprintf_unfiltered (gdb_stdlog,
"{ frame_func_unwind (fi=%d) -> 0x%s }\n",
fi->level, paddr_nz (fi->prev_func.addr));
}
return fi->prev_func.addr;
}
CORE_ADDR
get_frame_func (struct frame_info *fi)
{
return frame_func_unwind (fi->next);
}
static int
do_frame_register_read (void *src, int regnum, void *buf)
{
frame_register_read (src, regnum, buf);
return 1;
}
struct regcache *
frame_save_as_regcache (struct frame_info *this_frame)
{
struct regcache *regcache = regcache_xmalloc (current_gdbarch);
struct cleanup *cleanups = make_cleanup_regcache_xfree (regcache);
regcache_save (regcache, do_frame_register_read, this_frame);
discard_cleanups (cleanups);
return regcache;
}
void
frame_pop (struct frame_info *this_frame)
{
/* Make a copy of all the register values unwound from this frame.
Save them in a scratch buffer so that there isn't a race between
trying to extract the old values from the current_regcache while
at the same time writing new values into that same cache. */
struct regcache *scratch
= frame_save_as_regcache (get_prev_frame_1 (this_frame));
struct cleanup *cleanups = make_cleanup_regcache_xfree (scratch);
/* FIXME: cagney/2003-03-16: It should be possible to tell the
target's register cache that it is about to be hit with a burst
register transfer and that the sequence of register writes should
be batched. The pair target_prepare_to_store() and
target_store_registers() kind of suggest this functionality.
Unfortunately, they don't implement it. Their lack of a formal
definition can lead to targets writing back bogus values
(arguably a bug in the target code mind). */
/* Now copy those saved registers into the current regcache.
Here, regcache_cpy() calls regcache_restore(). */
regcache_cpy (current_regcache, scratch);
do_cleanups (cleanups);
/* We've made right mess of GDB's local state, just discard
everything. */
flush_cached_frames ();
}
void
frame_register_unwind (struct frame_info *frame, int regnum,
int *optimizedp, enum lval_type *lvalp,
CORE_ADDR *addrp, int *realnump, void *bufferp)
{
struct frame_unwind_cache *cache;
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "\
{ frame_register_unwind (frame=%d,regnum=%d(%s),...) ",
frame->level, regnum,
frame_map_regnum_to_name (frame, regnum));
}
/* Require all but BUFFERP to be valid. A NULL BUFFERP indicates
that the value proper does not need to be fetched. */
gdb_assert (optimizedp != NULL);
gdb_assert (lvalp != NULL);
gdb_assert (addrp != NULL);
gdb_assert (realnump != NULL);
/* gdb_assert (bufferp != NULL); */
/* NOTE: cagney/2002-11-27: A program trying to unwind a NULL frame
is broken. There is always a frame. If there, for some reason,
isn't a frame, there is some pretty busted code as it should have
detected the problem before calling here. */
gdb_assert (frame != NULL);
/* Find the unwinder. */
if (frame->unwind == NULL)
frame->unwind = frame_unwind_find_by_frame (frame->next,
&frame->prologue_cache);
/* Ask this frame to unwind its register. See comment in
"frame-unwind.h" for why NEXT frame and this unwind cache are
passed in. */
frame->unwind->prev_register (frame->next, &frame->prologue_cache, regnum,
optimizedp, lvalp, addrp, realnump, bufferp);
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "->");
fprintf_unfiltered (gdb_stdlog, " *optimizedp=%d", (*optimizedp));
fprintf_unfiltered (gdb_stdlog, " *lvalp=%d", (int) (*lvalp));
fprintf_unfiltered (gdb_stdlog, " *addrp=0x%s", paddr_nz ((*addrp)));
fprintf_unfiltered (gdb_stdlog, " *bufferp=");
if (bufferp == NULL)
fprintf_unfiltered (gdb_stdlog, "<NULL>");
else
{
int i;
const unsigned char *buf = bufferp;
fprintf_unfiltered (gdb_stdlog, "[");
for (i = 0; i < register_size (current_gdbarch, regnum); i++)
fprintf_unfiltered (gdb_stdlog, "%02x", buf[i]);
fprintf_unfiltered (gdb_stdlog, "]");
}
fprintf_unfiltered (gdb_stdlog, " }\n");
}
}
void
frame_register (struct frame_info *frame, int regnum,
int *optimizedp, enum lval_type *lvalp,
CORE_ADDR *addrp, int *realnump, void *bufferp)
{
/* Require all but BUFFERP to be valid. A NULL BUFFERP indicates
that the value proper does not need to be fetched. */
gdb_assert (optimizedp != NULL);
gdb_assert (lvalp != NULL);
gdb_assert (addrp != NULL);
gdb_assert (realnump != NULL);
/* gdb_assert (bufferp != NULL); */
/* Obtain the register value by unwinding the register from the next
(more inner frame). */
gdb_assert (frame != NULL && frame->next != NULL);
frame_register_unwind (frame->next, regnum, optimizedp, lvalp, addrp,
realnump, bufferp);
}
void
frame_unwind_register (struct frame_info *frame, int regnum, void *buf)
{
int optimized;
CORE_ADDR addr;
int realnum;
enum lval_type lval;
frame_register_unwind (frame, regnum, &optimized, &lval, &addr,
&realnum, buf);
}
void
get_frame_register (struct frame_info *frame,
int regnum, void *buf)
{
frame_unwind_register (frame->next, regnum, buf);
}
LONGEST
frame_unwind_register_signed (struct frame_info *frame, int regnum)
{
char buf[MAX_REGISTER_SIZE];
frame_unwind_register (frame, regnum, buf);
return extract_signed_integer (buf, register_size (get_frame_arch (frame),
regnum));
}
LONGEST
get_frame_register_signed (struct frame_info *frame, int regnum)
{
return frame_unwind_register_signed (frame->next, regnum);
}
ULONGEST
frame_unwind_register_unsigned (struct frame_info *frame, int regnum)
{
char buf[MAX_REGISTER_SIZE];
frame_unwind_register (frame, regnum, buf);
return extract_unsigned_integer (buf, register_size (get_frame_arch (frame),
regnum));
}
ULONGEST
get_frame_register_unsigned (struct frame_info *frame, int regnum)
{
return frame_unwind_register_unsigned (frame->next, regnum);
}
void
frame_unwind_unsigned_register (struct frame_info *frame, int regnum,
ULONGEST *val)
{
char buf[MAX_REGISTER_SIZE];
frame_unwind_register (frame, regnum, buf);
(*val) = extract_unsigned_integer (buf,
register_size (get_frame_arch (frame),
regnum));
}
void
put_frame_register (struct frame_info *frame, int regnum, const void *buf)
{
struct gdbarch *gdbarch = get_frame_arch (frame);
int realnum;
int optim;
enum lval_type lval;
CORE_ADDR addr;
frame_register (frame, regnum, &optim, &lval, &addr, &realnum, NULL);
if (optim)
error ("Attempt to assign to a value that was optimized out.");
switch (lval)
{
case lval_memory:
{
/* FIXME: write_memory doesn't yet take constant buffers.
Arrrg! */
char tmp[MAX_REGISTER_SIZE];
memcpy (tmp, buf, register_size (gdbarch, regnum));
write_memory (addr, tmp, register_size (gdbarch, regnum));
break;
}
case lval_register:
regcache_cooked_write (current_regcache, realnum, buf);
break;
default:
error ("Attempt to assign to an unmodifiable value.");
}
}
/* frame_register_read ()
Find and return the value of REGNUM for the specified stack frame.
The number of bytes copied is REGISTER_SIZE (REGNUM).
Returns 0 if the register value could not be found. */
int
frame_register_read (struct frame_info *frame, int regnum, void *myaddr)
{
int optimized;
enum lval_type lval;
CORE_ADDR addr;
int realnum;
frame_register (frame, regnum, &optimized, &lval, &addr, &realnum, myaddr);
/* FIXME: cagney/2002-05-15: This test is just bogus.
It indicates that the target failed to supply a value for a
register because it was "not available" at this time. Problem
is, the target still has the register and so get saved_register()
may be returning a value saved on the stack. */
if (register_cached (regnum) < 0)
return 0; /* register value not available */
return !optimized;
}
/* Map between a frame register number and its name. A frame register
space is a superset of the cooked register space --- it also
includes builtin registers. */
int
frame_map_name_to_regnum (struct frame_info *frame, const char *name, int len)
{
return user_reg_map_name_to_regnum (get_frame_arch (frame), name, len);
}
const char *
frame_map_regnum_to_name (struct frame_info *frame, int regnum)
{
return user_reg_map_regnum_to_name (get_frame_arch (frame), regnum);
}
/* Create a sentinel frame. */
static struct frame_info *
create_sentinel_frame (struct regcache *regcache)
{
struct frame_info *frame = FRAME_OBSTACK_ZALLOC (struct frame_info);
frame->level = -1;
/* Explicitly initialize the sentinel frame's cache. Provide it
with the underlying regcache. In the future additional
information, such as the frame's thread will be added. */
frame->prologue_cache = sentinel_frame_cache (regcache);
/* For the moment there is only one sentinel frame implementation. */
frame->unwind = sentinel_frame_unwind;
/* Link this frame back to itself. The frame is self referential
(the unwound PC is the same as the pc), so make it so. */
frame->next = frame;
/* Make the sentinel frame's ID valid, but invalid. That way all
comparisons with it should fail. */
frame->this_id.p = 1;
frame->this_id.value = null_frame_id;
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "{ create_sentinel_frame (...) -> ");
fprint_frame (gdb_stdlog, frame);
fprintf_unfiltered (gdb_stdlog, " }\n");
}
return frame;
}
/* Info about the innermost stack frame (contents of FP register) */
static struct frame_info *current_frame;
/* Cache for frame addresses already read by gdb. Valid only while
inferior is stopped. Control variables for the frame cache should
be local to this module. */
static struct obstack frame_cache_obstack;
void *
frame_obstack_zalloc (unsigned long size)
{
void *data = obstack_alloc (&frame_cache_obstack, size);
memset (data, 0, size);
return data;
}
/* Return the innermost (currently executing) stack frame. This is
split into two functions. The function unwind_to_current_frame()
is wrapped in catch exceptions so that, even when the unwind of the
sentinel frame fails, the function still returns a stack frame. */
static int
unwind_to_current_frame (struct ui_out *ui_out, void *args)
{
struct frame_info *frame = get_prev_frame (args);
/* A sentinel frame can fail to unwind, e.g., because its PC value
lands in somewhere like start. */
if (frame == NULL)
return 1;
current_frame = frame;
return 0;
}
struct frame_info *
get_current_frame (void)
{
/* First check, and report, the lack of registers. Having GDB
report "No stack!" or "No memory" when the target doesn't even
have registers is very confusing. Besides, "printcmd.exp"
explicitly checks that ``print $pc'' with no registers prints "No
registers". */
if (!target_has_registers)
error ("No registers.");
if (!target_has_stack)
error ("No stack.");
if (!target_has_memory)
error ("No memory.");
if (current_frame == NULL)
{
struct frame_info *sentinel_frame =
create_sentinel_frame (current_regcache);
if (catch_exceptions (uiout, unwind_to_current_frame, sentinel_frame,
NULL, RETURN_MASK_ERROR) != 0)
{
/* Oops! Fake a current frame? Is this useful? It has a PC
of zero, for instance. */
current_frame = sentinel_frame;
}
}
return current_frame;
}
/* The "selected" stack frame is used by default for local and arg
access. May be zero, for no selected frame. */
struct frame_info *deprecated_selected_frame;
/* Return the selected frame. Always non-NULL (unless there isn't an
inferior sufficient for creating a frame) in which case an error is
thrown. */
struct frame_info *
get_selected_frame (void)
{
if (deprecated_selected_frame == NULL)
/* Hey! Don't trust this. It should really be re-finding the
last selected frame of the currently selected thread. This,
though, is better than nothing. */
select_frame (get_current_frame ());
/* There is always a frame. */
gdb_assert (deprecated_selected_frame != NULL);
return deprecated_selected_frame;
}
/* This is a variant of get_selected_frame() which can be called when
the inferior does not have a frame; in that case it will return
NULL instead of calling error(). */
struct frame_info *
deprecated_safe_get_selected_frame (void)
{
if (!target_has_registers || !target_has_stack || !target_has_memory)
return NULL;
return get_selected_frame ();
}
/* Select frame FI (or NULL - to invalidate the current frame). */
void
select_frame (struct frame_info *fi)
{
struct symtab *s;
deprecated_selected_frame = fi;
/* NOTE: cagney/2002-05-04: FI can be NULL. This occurs when the
frame is being invalidated. */
if (deprecated_selected_frame_level_changed_hook)
deprecated_selected_frame_level_changed_hook (frame_relative_level (fi));
/* FIXME: kseitz/2002-08-28: It would be nice to call
selected_frame_level_changed_event() right here, but due to limitations
in the current interfaces, we would end up flooding UIs with events
because select_frame() is used extensively internally.
Once we have frame-parameterized frame (and frame-related) commands,
the event notification can be moved here, since this function will only
be called when the user's selected frame is being changed. */
/* Ensure that symbols for this frame are read in. Also, determine the
source language of this frame, and switch to it if desired. */
if (fi)
{
/* We retrieve the frame's symtab by using the frame PC. However
we cannot use the frame PC as-is, because it usually points to
the instruction following the "call", which is sometimes the
first instruction of another function. So we rely on
get_frame_address_in_block() which provides us with a PC which
is guaranteed to be inside the frame's code block. */
s = find_pc_symtab (get_frame_address_in_block (fi));
if (s
&& s->language != current_language->la_language
&& s->language != language_unknown
&& language_mode == language_mode_auto)
{
set_language (s->language);
}
}
}
/* Create an arbitrary (i.e. address specified by user) or innermost frame.
Always returns a non-NULL value. */
struct frame_info *
create_new_frame (CORE_ADDR addr, CORE_ADDR pc)
{
struct frame_info *fi;
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog,
"{ create_new_frame (addr=0x%s, pc=0x%s) ",
paddr_nz (addr), paddr_nz (pc));
}
fi = frame_obstack_zalloc (sizeof (struct frame_info));
fi->next = create_sentinel_frame (current_regcache);
/* Select/initialize both the unwind function and the frame's type
based on the PC. */
fi->unwind = frame_unwind_find_by_frame (fi->next, &fi->prologue_cache);
fi->this_id.p = 1;
deprecated_update_frame_base_hack (fi, addr);
deprecated_update_frame_pc_hack (fi, pc);
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame (gdb_stdlog, fi);
fprintf_unfiltered (gdb_stdlog, " }\n");
}
return fi;
}
/* Return the frame that THIS_FRAME calls (NULL if THIS_FRAME is the
innermost frame). Be careful to not fall off the bottom of the
frame chain and onto the sentinel frame. */
struct frame_info *
get_next_frame (struct frame_info *this_frame)
{
if (this_frame->level > 0)
return this_frame->next;
else
return NULL;
}
/* Observer for the target_changed event. */
void
frame_observer_target_changed (struct target_ops *target)
{
flush_cached_frames ();
}
/* Flush the entire frame cache. */
void
flush_cached_frames (void)
{
/* Since we can't really be sure what the first object allocated was */
obstack_free (&frame_cache_obstack, 0);
obstack_init (&frame_cache_obstack);
current_frame = NULL; /* Invalidate cache */
select_frame (NULL);
annotate_frames_invalid ();
if (frame_debug)
fprintf_unfiltered (gdb_stdlog, "{ flush_cached_frames () }\n");
}
/* Flush the frame cache, and start a new one if necessary. */
void
reinit_frame_cache (void)
{
flush_cached_frames ();
/* FIXME: The inferior_ptid test is wrong if there is a corefile. */
if (PIDGET (inferior_ptid) != 0)
{
select_frame (get_current_frame ());
}
}
/* Return a "struct frame_info" corresponding to the frame that called
THIS_FRAME. Returns NULL if there is no such frame.
Unlike get_prev_frame, this function always tries to unwind the
frame. */
static struct frame_info *
get_prev_frame_1 (struct frame_info *this_frame)
{
struct frame_info *prev_frame;
struct frame_id this_id;
gdb_assert (this_frame != NULL);
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "{ get_prev_frame_1 (this_frame=");
if (this_frame != NULL)
fprintf_unfiltered (gdb_stdlog, "%d", this_frame->level);
else
fprintf_unfiltered (gdb_stdlog, "<NULL>");
fprintf_unfiltered (gdb_stdlog, ") ");
}
/* Only try to do the unwind once. */
if (this_frame->prev_p)
{
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame (gdb_stdlog, this_frame->prev);
fprintf_unfiltered (gdb_stdlog, " // cached \n");
}
return this_frame->prev;
}
this_frame->prev_p = 1;
/* Check that this frame's ID was valid. If it wasn't, don't try to
unwind to the prev frame. Be careful to not apply this test to
the sentinel frame. */
this_id = get_frame_id (this_frame);
if (this_frame->level >= 0 && !frame_id_p (this_id))
{
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame (gdb_stdlog, NULL);
fprintf_unfiltered (gdb_stdlog, " // this ID is NULL }\n");
}
return NULL;
}
/* Check that this frame's ID isn't inner to (younger, below, next)
the next frame. This happens when a frame unwind goes backwards.
Exclude signal trampolines (due to sigaltstack the frame ID can
go backwards) and sentinel frames (the test is meaningless). */
if (this_frame->next->level >= 0
&& this_frame->next->unwind->type != SIGTRAMP_FRAME
&& frame_id_inner (this_id, get_frame_id (this_frame->next)))
error ("Previous frame inner to this frame (corrupt stack?)");
/* Check that this and the next frame are not identical. If they
are, there is most likely a stack cycle. As with the inner-than
test above, avoid comparing the inner-most and sentinel frames. */
if (this_frame->level > 0
&& frame_id_eq (this_id, get_frame_id (this_frame->next)))
error ("Previous frame identical to this frame (corrupt stack?)");
/* Allocate the new frame but do not wire it in to the frame chain.
Some (bad) code in INIT_FRAME_EXTRA_INFO tries to look along
frame->next to pull some fancy tricks (of course such code is, by
definition, recursive). Try to prevent it.
There is no reason to worry about memory leaks, should the
remainder of the function fail. The allocated memory will be
quickly reclaimed when the frame cache is flushed, and the `we've
been here before' check above will stop repeated memory
allocation calls. */
prev_frame = FRAME_OBSTACK_ZALLOC (struct frame_info);
prev_frame->level = this_frame->level + 1;
/* Don't yet compute ->unwind (and hence ->type). It is computed
on-demand in get_frame_type, frame_register_unwind, and
get_frame_id. */
/* Don't yet compute the frame's ID. It is computed on-demand by
get_frame_id(). */
/* The unwound frame ID is validate at the start of this function,
as part of the logic to decide if that frame should be further
unwound, and not here while the prev frame is being created.
Doing this makes it possible for the user to examine a frame that
has an invalid frame ID.
Some very old VAX code noted: [...] For the sake of argument,
suppose that the stack is somewhat trashed (which is one reason
that "info frame" exists). So, return 0 (indicating we don't
know the address of the arglist) if we don't know what frame this
frame calls. */
/* Link it in. */
this_frame->prev = prev_frame;
prev_frame->next = this_frame;
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame (gdb_stdlog, prev_frame);
fprintf_unfiltered (gdb_stdlog, " }\n");
}
return prev_frame;
}
/* Debug routine to print a NULL frame being returned. */
static void
frame_debug_got_null_frame (struct ui_file *file,
struct frame_info *this_frame,
const char *reason)
{
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "{ get_prev_frame (this_frame=");
if (this_frame != NULL)
fprintf_unfiltered (gdb_stdlog, "%d", this_frame->level);
else
fprintf_unfiltered (gdb_stdlog, "<NULL>");
fprintf_unfiltered (gdb_stdlog, ") -> // %s}\n", reason);
}
}
/* Is this (non-sentinel) frame in the "main"() function? */
static int
inside_main_func (struct frame_info *this_frame)
{
struct minimal_symbol *msymbol;
CORE_ADDR maddr;
if (symfile_objfile == 0)
return 0;
msymbol = lookup_minimal_symbol (main_name (), NULL, symfile_objfile);
if (msymbol == NULL)
return 0;
/* Make certain that the code, and not descriptor, address is
returned. */
maddr = gdbarch_convert_from_func_ptr_addr (current_gdbarch,
SYMBOL_VALUE_ADDRESS (msymbol),
&current_target);
return maddr == get_frame_func (this_frame);
}
/* Return a structure containing various interesting information about
the frame that called THIS_FRAME. Returns NULL if there is entier
no such frame or the frame fails any of a set of target-independent
condition that should terminate the frame chain (e.g., as unwinding
past main()).
This function should not contain target-dependent tests, such as
checking whether the program-counter is zero. */
struct frame_info *
get_prev_frame (struct frame_info *this_frame)
{
struct frame_info *prev_frame;
/* Return the inner-most frame, when the caller passes in NULL. */
/* NOTE: cagney/2002-11-09: Not sure how this would happen. The
caller should have previously obtained a valid frame using
get_selected_frame() and then called this code - only possibility
I can think of is code behaving badly.
NOTE: cagney/2003-01-10: Talk about code behaving badly. Check
block_innermost_frame(). It does the sequence: frame = NULL;
while (1) { frame = get_prev_frame (frame); .... }. Ulgh! Why
it couldn't be written better, I don't know.
NOTE: cagney/2003-01-11: I suspect what is happening in
block_innermost_frame() is, when the target has no state
(registers, memory, ...), it is still calling this function. The
assumption being that this function will return NULL indicating
that a frame isn't possible, rather than checking that the target
has state and then calling get_current_frame() and
get_prev_frame(). This is a guess mind. */
if (this_frame == NULL)
{
/* NOTE: cagney/2002-11-09: There was a code segment here that
would error out when CURRENT_FRAME was NULL. The comment
that went with it made the claim ...
``This screws value_of_variable, which just wants a nice
clean NULL return from block_innermost_frame if there are no
frames. I don't think I've ever seen this message happen
otherwise. And returning NULL here is a perfectly legitimate
thing to do.''
Per the above, this code shouldn't even be called with a NULL
THIS_FRAME. */
frame_debug_got_null_frame (gdb_stdlog, this_frame, "this_frame NULL");
return current_frame;
}
/* There is always a frame. If this assertion fails, suspect that
something should be calling get_selected_frame() or
get_current_frame(). */
gdb_assert (this_frame != NULL);
if (this_frame->level >= 0
&& !backtrace_past_main
&& inside_main_func (this_frame))
/* Don't unwind past main(). Note, this is done _before_ the
frame has been marked as previously unwound. That way if the
user later decides to enable unwinds past main(), that will
automatically happen. */
{
frame_debug_got_null_frame (gdb_stdlog, this_frame, "inside main func");
return NULL;
}
if (this_frame->level > backtrace_limit)
{
error ("Backtrace limit of %d exceeded", backtrace_limit);
}
/* If we're already inside the entry function for the main objfile,
then it isn't valid. Don't apply this test to a dummy frame -
dummy frame PCs typically land in the entry func. Don't apply
this test to the sentinel frame. Sentinel frames should always
be allowed to unwind. */
/* NOTE: cagney/2003-02-25: Don't enable until someone has found
hard evidence that this is needed. */
/* NOTE: cagney/2003-07-07: Fixed a bug in inside_main_func() -
wasn't checking for "main" in the minimal symbols. With that
fixed asm-source tests now stop in "main" instead of halting the
backtrace in weird and wonderful ways somewhere inside the entry
file. Suspect that tests for inside the entry file/func were
added to work around that (now fixed) case. */
/* NOTE: cagney/2003-07-15: danielj (if I'm reading it right)
suggested having the inside_entry_func test use the
inside_main_func() msymbol trick (along with entry_point_address()
I guess) to determine the address range of the start function.
That should provide a far better stopper than the current
heuristics. */
/* NOTE: cagney/2003-07-15: Need to add a "set backtrace
beyond-entry-func" command so that this can be selectively
disabled. */
if (0
#if 0
&& backtrace_beyond_entry_func
#endif
&& this_frame->unwind->type != DUMMY_FRAME && this_frame->level >= 0
&& inside_entry_func (this_frame))
{
frame_debug_got_null_frame (gdb_stdlog, this_frame, "inside entry func");
return NULL;
}
return get_prev_frame_1 (this_frame);
}
CORE_ADDR
get_frame_pc (struct frame_info *frame)
{
gdb_assert (frame->next != NULL);
return frame_pc_unwind (frame->next);
}
/* Return an address of that falls within the frame's code block. */
CORE_ADDR
frame_unwind_address_in_block (struct frame_info *next_frame)
{
/* A draft address. */
CORE_ADDR pc = frame_pc_unwind (next_frame);
/* If THIS frame is not inner most (i.e., NEXT isn't the sentinel),
and NEXT is `normal' (i.e., not a sigtramp, dummy, ....) THIS
frame's PC ends up pointing at the instruction fallowing the
"call". Adjust that PC value so that it falls on the call
instruction (which, hopefully, falls within THIS frame's code
block. So far it's proved to be a very good approximation. See
get_frame_type() for why ->type can't be used. */
if (next_frame->level >= 0
&& get_frame_type (next_frame) == NORMAL_FRAME)
--pc;
return pc;
}
CORE_ADDR
get_frame_address_in_block (struct frame_info *this_frame)
{
return frame_unwind_address_in_block (this_frame->next);
}
static int
pc_notcurrent (struct frame_info *frame)
{
/* If FRAME is not the innermost frame, that normally means that
FRAME->pc points at the return instruction (which is *after* the
call instruction), and we want to get the line containing the
call (because the call is where the user thinks the program is).
However, if the next frame is either a SIGTRAMP_FRAME or a
DUMMY_FRAME, then the next frame will contain a saved interrupt
PC and such a PC indicates the current (rather than next)
instruction/line, consequently, for such cases, want to get the
line containing fi->pc. */
struct frame_info *next = get_next_frame (frame);
int notcurrent = (next != NULL && get_frame_type (next) == NORMAL_FRAME);
return notcurrent;
}
void
find_frame_sal (struct frame_info *frame, struct symtab_and_line *sal)
{
(*sal) = find_pc_line (get_frame_pc (frame), pc_notcurrent (frame));
}
/* Per "frame.h", return the ``address'' of the frame. Code should
really be using get_frame_id(). */
CORE_ADDR
get_frame_base (struct frame_info *fi)
{
return get_frame_id (fi).stack_addr;
}
/* High-level offsets into the frame. Used by the debug info. */
CORE_ADDR
get_frame_base_address (struct frame_info *fi)
{
if (get_frame_type (fi) != NORMAL_FRAME)
return 0;
if (fi->base == NULL)
fi->base = frame_base_find_by_frame (fi->next);
/* Sneaky: If the low-level unwind and high-level base code share a
common unwinder, let them share the prologue cache. */
if (fi->base->unwind == fi->unwind)
return fi->base->this_base (fi->next, &fi->prologue_cache);
return fi->base->this_base (fi->next, &fi->base_cache);
}
CORE_ADDR
get_frame_locals_address (struct frame_info *fi)
{
void **cache;
if (get_frame_type (fi) != NORMAL_FRAME)
return 0;
/* If there isn't a frame address method, find it. */
if (fi->base == NULL)
fi->base = frame_base_find_by_frame (fi->next);
/* Sneaky: If the low-level unwind and high-level base code share a
common unwinder, let them share the prologue cache. */
if (fi->base->unwind == fi->unwind)
cache = &fi->prologue_cache;
else
cache = &fi->base_cache;
return fi->base->this_locals (fi->next, cache);
}
CORE_ADDR
get_frame_args_address (struct frame_info *fi)
{
void **cache;
if (get_frame_type (fi) != NORMAL_FRAME)
return 0;
/* If there isn't a frame address method, find it. */
if (fi->base == NULL)
fi->base = frame_base_find_by_frame (fi->next);
/* Sneaky: If the low-level unwind and high-level base code share a
common unwinder, let them share the prologue cache. */
if (fi->base->unwind == fi->unwind)
cache = &fi->prologue_cache;
else
cache = &fi->base_cache;
return fi->base->this_args (fi->next, cache);
}
/* Level of the selected frame: 0 for innermost, 1 for its caller, ...
or -1 for a NULL frame. */
int
frame_relative_level (struct frame_info *fi)
{
if (fi == NULL)
return -1;
else
return fi->level;
}
enum frame_type
get_frame_type (struct frame_info *frame)
{
if (frame->unwind == NULL)
/* Initialize the frame's unwinder because that's what
provides the frame's type. */
frame->unwind = frame_unwind_find_by_frame (frame->next,
&frame->prologue_cache);
return frame->unwind->type;
}
void
deprecated_update_frame_pc_hack (struct frame_info *frame, CORE_ADDR pc)
{
if (frame_debug)
fprintf_unfiltered (gdb_stdlog,
"{ deprecated_update_frame_pc_hack (frame=%d,pc=0x%s) }\n",
frame->level, paddr_nz (pc));
/* NOTE: cagney/2003-03-11: Some architectures (e.g., Arm) are
maintaining a locally allocated frame object. Since such frames
are not in the frame chain, it isn't possible to assume that the
frame has a next. Sigh. */
if (frame->next != NULL)
{
/* While we're at it, update this frame's cached PC value, found
in the next frame. Oh for the day when "struct frame_info"
is opaque and this hack on hack can just go away. */
frame->next->prev_pc.value = pc;
frame->next->prev_pc.p = 1;
}
}
void
deprecated_update_frame_base_hack (struct frame_info *frame, CORE_ADDR base)
{
if (frame_debug)
fprintf_unfiltered (gdb_stdlog,
"{ deprecated_update_frame_base_hack (frame=%d,base=0x%s) }\n",
frame->level, paddr_nz (base));
/* See comment in "frame.h". */
frame->this_id.value.stack_addr = base;
}
/* Memory access methods. */
void
get_frame_memory (struct frame_info *this_frame, CORE_ADDR addr, void *buf,
int len)
{
read_memory (addr, buf, len);
}
LONGEST
get_frame_memory_signed (struct frame_info *this_frame, CORE_ADDR addr,
int len)
{
return read_memory_integer (addr, len);
}
ULONGEST
get_frame_memory_unsigned (struct frame_info *this_frame, CORE_ADDR addr,
int len)
{
return read_memory_unsigned_integer (addr, len);
}
int
safe_frame_unwind_memory (struct frame_info *this_frame,
CORE_ADDR addr, void *buf, int len)
{
/* NOTE: deprecated_read_memory_nobpt returns zero on success! */
return !deprecated_read_memory_nobpt (addr, buf, len);
}
/* Architecture method. */
struct gdbarch *
get_frame_arch (struct frame_info *this_frame)
{
return current_gdbarch;
}
/* Stack pointer methods. */
CORE_ADDR
get_frame_sp (struct frame_info *this_frame)
{
return frame_sp_unwind (this_frame->next);
}
CORE_ADDR
frame_sp_unwind (struct frame_info *next_frame)
{
/* Normality - an architecture that provides a way of obtaining any
frame inner-most address. */
if (gdbarch_unwind_sp_p (current_gdbarch))
return gdbarch_unwind_sp (current_gdbarch, next_frame);
/* Things are looking grim. If it's the inner-most frame and there
is a TARGET_READ_SP, then that can be used. */
if (next_frame->level < 0 && TARGET_READ_SP_P ())
return TARGET_READ_SP ();
/* Now things are really are grim. Hope that the value returned by
the SP_REGNUM register is meaningful. */
if (SP_REGNUM >= 0)
{
ULONGEST sp;
frame_unwind_unsigned_register (next_frame, SP_REGNUM, &sp);
return sp;
}
internal_error (__FILE__, __LINE__, "Missing unwind SP method");
}
extern initialize_file_ftype _initialize_frame; /* -Wmissing-prototypes */
static struct cmd_list_element *set_backtrace_cmdlist;
static struct cmd_list_element *show_backtrace_cmdlist;
static void
set_backtrace_cmd (char *args, int from_tty)
{
help_list (set_backtrace_cmdlist, "set backtrace ", -1, gdb_stdout);
}
static void
show_backtrace_cmd (char *args, int from_tty)
{
cmd_show_list (show_backtrace_cmdlist, from_tty, "");
}
void
_initialize_frame (void)
{
obstack_init (&frame_cache_obstack);
observer_attach_target_changed (frame_observer_target_changed);
add_prefix_cmd ("backtrace", class_maintenance, set_backtrace_cmd, "\
Set backtrace specific variables.\n\
Configure backtrace variables such as the backtrace limit",
&set_backtrace_cmdlist, "set backtrace ",
0/*allow-unknown*/, &setlist);
add_prefix_cmd ("backtrace", class_maintenance, show_backtrace_cmd, "\
Show backtrace specific variables\n\
Show backtrace variables such as the backtrace limit",
&show_backtrace_cmdlist, "show backtrace ",
0/*allow-unknown*/, &showlist);
add_setshow_boolean_cmd ("past-main", class_obscure,
&backtrace_past_main, "\
Set whether backtraces should continue past \"main\".", "\
Show whether backtraces should continue past \"main\".", "\
Normally the caller of \"main\" is not of interest, so GDB will terminate\n\
the backtrace at \"main\". Set this variable if you need to see the rest\n\
of the stack trace.", "\
Whether backtraces should continue past \"main\" is %s.",
NULL, NULL, &set_backtrace_cmdlist,
&show_backtrace_cmdlist);
add_setshow_uinteger_cmd ("limit", class_obscure,
&backtrace_limit, "\
Set an upper bound on the number of backtrace levels.", "\
Show the upper bound on the number of backtrace levels.", "\
No more than the specified number of frames can be displayed or examined.\n\
Zero is unlimited.", "\
An upper bound on the number of backtrace levels is %s.",
NULL, NULL, &set_backtrace_cmdlist,
&show_backtrace_cmdlist);
/* Debug this files internals. */
deprecated_add_show_from_set
(add_set_cmd ("frame", class_maintenance, var_zinteger,
&frame_debug, "Set frame debugging.\n\
When non-zero, frame specific internal debugging is enabled.", &setdebuglist),
&showdebuglist);
}
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