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binutils-gdb/gdb/frame.c

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/* Cache and manage frames for GDB, the GNU debugger.
Copyright (C) 1986, 1987, 1989, 1991, 1994, 1995, 1996, 1998, 2000, 2001,
2002, 2003, 2004, 2007, 2008 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "defs.h"
#include "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"
#include "exceptions.h"
#include "gdbthread.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 */
/* The reason why we could not set PREV, or UNWIND_NO_REASON if we
could. Only valid when PREV_P is set. */
enum unwind_stop_reason stop_reason;
};
/* Flag to control debugging. */
int frame_debug;
static void
show_frame_debug (struct ui_file *file, int from_tty,
struct cmd_list_element *c, const char *value)
{
fprintf_filtered (file, _("Frame debugging is %s.\n"), value);
}
/* Flag to indicate whether backtraces should stop at main et.al. */
static int backtrace_past_main;
static void
show_backtrace_past_main (struct ui_file *file, int from_tty,
struct cmd_list_element *c, const char *value)
{
fprintf_filtered (file, _("\
Whether backtraces should continue past \"main\" is %s.\n"),
value);
}
static int backtrace_past_entry;
static void
show_backtrace_past_entry (struct ui_file *file, int from_tty,
struct cmd_list_element *c, const char *value)
{
fprintf_filtered (file, _("\
Whether backtraces should continue past the entry point of a program is %s.\n"),
value);
}
static int backtrace_limit = INT_MAX;
static void
show_backtrace_limit (struct ui_file *file, int from_tty,
struct cmd_list_element *c, const char *value)
{
fprintf_filtered (file, _("\
An upper bound on the number of backtrace levels is %s.\n"),
value);
}
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, &fi->prologue_cache);
/* Find THIS frame's ID. */
fi->unwind->this_id (fi, &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;
}
/* Safety net to check whether frame ID L should be inner to
frame ID R, according to their stack addresses.
This method cannot be used to compare arbitrary frames, as the
ranges of valid stack addresses may be discontiguous (e.g. due
to sigaltstack).
However, it can be used as safety net to discover invalid frame
IDs in certain circumstances.
* If frame NEXT is the immediate inner frame to THIS, and NEXT
is a NORMAL frame, then the stack address of NEXT must be
inner-than-or-equal to the stack address of THIS.
Therefore, if frame_id_inner (THIS, NEXT) holds, some unwind
error has occurred.
* If frame NEXT is the immediate inner frame to THIS, and NEXT
is a NORMAL frame, and NEXT and THIS have different stack
addresses, no other frame in the frame chain may have a stack
address in between.
Therefore, if frame_id_inner (TEST, THIS) holds, but
frame_id_inner (TEST, NEXT) does not hold, TEST cannot refer
to a valid frame in the frame chain. */
static int
frame_id_inner (struct gdbarch *gdbarch, 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 = gdbarch_inner_than (gdbarch, 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, *prev_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 = prev_frame)
{
struct frame_id this = get_frame_id (frame);
if (frame_id_eq (id, this))
/* An exact match. */
return frame;
prev_frame = get_prev_frame (frame);
if (!prev_frame)
return NULL;
/* As a safety net to avoid unnecessary backtracing while trying
to find an invalid ID, we check for a common situation where
we can detect from comparing stack addresses that no other
frame in the current frame chain can have this ID. See the
comment at frame_id_inner for details. */
if (get_frame_type (frame) == NORMAL_FRAME
&& !frame_id_inner (get_frame_arch (frame), id, this)
&& frame_id_inner (get_frame_arch (prev_frame), id,
get_frame_id (prev_frame)))
return NULL;
}
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 (get_frame_arch (this_frame)))
{
/* 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 (get_frame_arch (this_frame), this_frame);
}
else
internal_error (__FILE__, __LINE__, _("No 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
get_frame_func (struct frame_info *this_frame)
{
struct frame_info *next_frame = this_frame->next;
if (!next_frame->prev_func.p)
{
/* Make certain that this, and not the adjacent, function is
found. */
CORE_ADDR addr_in_block = get_frame_address_in_block (this_frame);
next_frame->prev_func.p = 1;
next_frame->prev_func.addr = get_pc_function_start (addr_in_block);
if (frame_debug)
fprintf_unfiltered (gdb_stdlog,
"{ get_frame_func (this_frame=%d) -> 0x%s }\n",
this_frame->level,
paddr_nz (next_frame->prev_func.addr));
}
return next_frame->prev_func.addr;
}
static int
do_frame_register_read (void *src, int regnum, gdb_byte *buf)
{
return frame_register_read (src, regnum, buf);
}
struct regcache *
frame_save_as_regcache (struct frame_info *this_frame)
{
struct regcache *regcache = regcache_xmalloc (get_frame_arch (this_frame));
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)
{
struct frame_info *prev_frame;
struct regcache *scratch;
struct cleanup *cleanups;
/* Ensure that we have a frame to pop to. */
prev_frame = get_prev_frame_1 (this_frame);
if (!prev_frame)
error (_("Cannot pop the initial 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. */
scratch = frame_save_as_regcache (prev_frame);
cleanups = make_cleanup_regcache_xfree (scratch);
/* If we are popping a dummy frame, clean up the associated
data as well. */
if (get_frame_type (this_frame) == DUMMY_FRAME)
dummy_frame_pop (get_frame_id (this_frame));
/* 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 (get_current_regcache (), scratch);
do_cleanups (cleanups);
/* We've made right mess of GDB's local state, just discard
everything. */
reinit_frame_cache ();
}
void
frame_register_unwind (struct frame_info *frame, int regnum,
int *optimizedp, enum lval_type *lvalp,
CORE_ADDR *addrp, int *realnump, gdb_byte *bufferp)
{
struct value *value;
/* 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); */
value = frame_unwind_register_value (frame, regnum);
gdb_assert (value != NULL);
*optimizedp = value_optimized_out (value);
*lvalp = VALUE_LVAL (value);
*addrp = VALUE_ADDRESS (value);
*realnump = VALUE_REGNUM (value);
if (bufferp)
memcpy (bufferp, value_contents_all (value),
TYPE_LENGTH (value_type (value)));
/* Dispose of the new value. This prevents watchpoints from
trying to watch the saved frame pointer. */
release_value (value);
value_free (value);
}
void
frame_register (struct frame_info *frame, int regnum,
int *optimizedp, enum lval_type *lvalp,
CORE_ADDR *addrp, int *realnump, gdb_byte *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, gdb_byte *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, gdb_byte *buf)
{
frame_unwind_register (frame->next, regnum, buf);
}
struct value *
frame_unwind_register_value (struct frame_info *frame, int regnum)
{
struct value *value;
gdb_assert (frame != NULL);
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "\
{ frame_unwind_register_value (frame=%d,regnum=%d(%s),...) ",
frame->level, regnum,
user_reg_map_regnum_to_name
(get_frame_arch (frame), regnum));
}
/* Find the unwinder. */
if (frame->unwind == NULL)
frame->unwind = frame_unwind_find_by_frame (frame, &frame->prologue_cache);
/* Ask this frame to unwind its register. */
value = frame->unwind->prev_register (frame, &frame->prologue_cache, regnum);
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "->");
if (value_optimized_out (value))
fprintf_unfiltered (gdb_stdlog, " optimized out");
else
{
if (VALUE_LVAL (value) == lval_register)
fprintf_unfiltered (gdb_stdlog, " register=%d",
VALUE_REGNUM (value));
else if (VALUE_LVAL (value) == lval_memory)
fprintf_unfiltered (gdb_stdlog, " address=0x%s",
paddr_nz (VALUE_ADDRESS (value)));
else
fprintf_unfiltered (gdb_stdlog, " computed");
if (value_lazy (value))
fprintf_unfiltered (gdb_stdlog, " lazy");
else
{
int i;
const gdb_byte *buf = value_contents (value);
fprintf_unfiltered (gdb_stdlog, " bytes=");
fprintf_unfiltered (gdb_stdlog, "[");
for (i = 0; i < register_size (get_frame_arch (frame), regnum); i++)
fprintf_unfiltered (gdb_stdlog, "%02x", buf[i]);
fprintf_unfiltered (gdb_stdlog, "]");
}
}
fprintf_unfiltered (gdb_stdlog, " }\n");
}
return value;
}
struct value *
get_frame_register_value (struct frame_info *frame, int regnum)
{
return frame_unwind_register_value (frame->next, regnum);
}
LONGEST
frame_unwind_register_signed (struct frame_info *frame, int regnum)
{
gdb_byte 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)
{
gdb_byte 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
put_frame_register (struct frame_info *frame, int regnum,
const gdb_byte *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! */
gdb_byte 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 (get_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,
gdb_byte *myaddr)
{
int optimized;
enum lval_type lval;
CORE_ADDR addr;
int realnum;
frame_register (frame, regnum, &optimized, &lval, &addr, &realnum, myaddr);
return !optimized;
}
int
get_frame_register_bytes (struct frame_info *frame, int regnum,
CORE_ADDR offset, int len, gdb_byte *myaddr)
{
struct gdbarch *gdbarch = get_frame_arch (frame);
int i;
int maxsize;
int numregs;
/* Skip registers wholly inside of OFFSET. */
while (offset >= register_size (gdbarch, regnum))
{
offset -= register_size (gdbarch, regnum);
regnum++;
}
/* Ensure that we will not read beyond the end of the register file.
This can only ever happen if the debug information is bad. */
maxsize = -offset;
numregs = gdbarch_num_regs (gdbarch) + gdbarch_num_pseudo_regs (gdbarch);
for (i = regnum; i < numregs; i++)
{
int thissize = register_size (gdbarch, i);
if (thissize == 0)
break; /* This register is not available on this architecture. */
maxsize += thissize;
}
if (len > maxsize)
{
warning (_("Bad debug information detected: "
"Attempt to read %d bytes from registers."), len);
return 0;
}
/* Copy the data. */
while (len > 0)
{
int curr_len = register_size (gdbarch, regnum) - offset;
if (curr_len > len)
curr_len = len;
if (curr_len == register_size (gdbarch, regnum))
{
if (!frame_register_read (frame, regnum, myaddr))
return 0;
}
else
{
gdb_byte buf[MAX_REGISTER_SIZE];
if (!frame_register_read (frame, regnum, buf))
return 0;
memcpy (myaddr, buf + offset, curr_len);
}
myaddr += curr_len;
len -= curr_len;
offset = 0;
regnum++;
}
return 1;
}
void
put_frame_register_bytes (struct frame_info *frame, int regnum,
CORE_ADDR offset, int len, const gdb_byte *myaddr)
{
struct gdbarch *gdbarch = get_frame_arch (frame);
/* Skip registers wholly inside of OFFSET. */
while (offset >= register_size (gdbarch, regnum))
{
offset -= register_size (gdbarch, regnum);
regnum++;
}
/* Copy the data. */
while (len > 0)
{
int curr_len = register_size (gdbarch, regnum) - offset;
if (curr_len > len)
curr_len = len;
if (curr_len == register_size (gdbarch, regnum))
{
put_frame_register (frame, regnum, myaddr);
}
else
{
gdb_byte buf[MAX_REGISTER_SIZE];
frame_register_read (frame, regnum, buf);
memcpy (buf + offset, myaddr, curr_len);
put_frame_register (frame, regnum, buf);
}
myaddr += curr_len;
len -= curr_len;
offset = 0;
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 (is_executing (inferior_ptid))
error (_("Target is executing."));
if (current_frame == NULL)
{
struct frame_info *sentinel_frame =
create_sentinel_frame (get_current_regcache ());
if (catch_exceptions (uiout, unwind_to_current_frame, sentinel_frame,
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. */
static struct frame_info *selected_frame;
static int
has_stack_frames (void)
{
if (!target_has_registers || !target_has_stack || !target_has_memory)
return 0;
/* If the current thread is executing, don't try to read from
it. */
if (is_executing (inferior_ptid))
return 0;
return 1;
}
/* 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 (const char *message)
{
if (selected_frame == NULL)
{
if (message != NULL && !has_stack_frames ())
error (("%s"), message);
/* 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 (selected_frame != NULL);
return 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 (!has_stack_frames ())
return NULL;
return get_selected_frame (NULL);
}
/* Select frame FI (or NULL - to invalidate the current frame). */
void
select_frame (struct frame_info *fi)
{
struct symtab *s;
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 (struct frame_info);
fi->next = create_sentinel_frame (get_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, &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)
{
reinit_frame_cache ();
}
/* Flush the entire frame cache. */
void
reinit_frame_cache (void)
{
struct frame_info *fi;
/* Tear down all frame caches. */
for (fi = current_frame; fi != NULL; fi = fi->prev)
{
if (fi->prologue_cache && fi->unwind->dealloc_cache)
fi->unwind->dealloc_cache (fi, fi->prologue_cache);
if (fi->base_cache && fi->base->unwind->dealloc_cache)
fi->base->unwind->dealloc_cache (fi, fi->base_cache);
}
/* Since we can't really be sure what the first object allocated was */
obstack_free (&frame_cache_obstack, 0);
obstack_init (&frame_cache_obstack);
if (current_frame != NULL)
annotate_frames_invalid ();
current_frame = NULL; /* Invalidate cache */
select_frame (NULL);
if (frame_debug)
fprintf_unfiltered (gdb_stdlog, "{ reinit_frame_cache () }\n");
}
/* Find where a register is saved (in memory or another register).
The result of frame_register_unwind is just where it is saved
relative to this particular frame. */
static void
frame_register_unwind_location (struct frame_info *this_frame, int regnum,
int *optimizedp, enum lval_type *lvalp,
CORE_ADDR *addrp, int *realnump)
{
gdb_assert (this_frame == NULL || this_frame->level >= 0);
while (this_frame != NULL)
{
frame_register_unwind (this_frame, regnum, optimizedp, lvalp,
addrp, realnump, NULL);
if (*optimizedp)
break;
if (*lvalp != lval_register)
break;
regnum = *realnump;
this_frame = get_next_frame (this_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;
struct gdbarch *gdbarch;
gdb_assert (this_frame != NULL);
gdbarch = get_frame_arch (this_frame);
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;
}
/* If the frame unwinder hasn't been selected yet, we must do so
before setting prev_p; otherwise the check for misbehaved
sniffers will think that this frame's sniffer tried to unwind
further (see frame_cleanup_after_sniffer). */
if (this_frame->unwind == NULL)
this_frame->unwind
= frame_unwind_find_by_frame (this_frame, &this_frame->prologue_cache);
this_frame->prev_p = 1;
this_frame->stop_reason = UNWIND_NO_REASON;
/* 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");
}
this_frame->stop_reason = UNWIND_NULL_ID;
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.
This check is valid only if the next frame is NORMAL. See the
comment at frame_id_inner for details. */
if (this_frame->next->unwind->type == NORMAL_FRAME
&& frame_id_inner (get_frame_arch (this_frame->next), this_id,
get_frame_id (this_frame->next)))
{
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame (gdb_stdlog, NULL);
fprintf_unfiltered (gdb_stdlog, " // this frame ID is inner }\n");
}
this_frame->stop_reason = UNWIND_INNER_ID;
return NULL;
}
/* 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)))
{
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame (gdb_stdlog, NULL);
fprintf_unfiltered (gdb_stdlog, " // this frame has same ID }\n");
}
this_frame->stop_reason = UNWIND_SAME_ID;
return NULL;
}
/* Check that this and the next frame do not unwind the PC register
to the same memory location. If they do, then even though they
have different frame IDs, the new frame will be bogus; two
functions can't share a register save slot for the PC. This can
happen when the prologue analyzer finds a stack adjustment, but
no PC save.
This check does assume that the "PC register" is roughly a
traditional PC, even if the gdbarch_unwind_pc method adjusts
it (we do not rely on the value, only on the unwound PC being
dependent on this value). A potential improvement would be
to have the frame prev_pc method and the gdbarch unwind_pc
method set the same lval and location information as
frame_register_unwind. */
if (this_frame->level > 0
&& gdbarch_pc_regnum (gdbarch) >= 0
&& get_frame_type (this_frame) == NORMAL_FRAME
&& get_frame_type (this_frame->next) == NORMAL_FRAME)
{
int optimized, realnum, nrealnum;
enum lval_type lval, nlval;
CORE_ADDR addr, naddr;
frame_register_unwind_location (this_frame,
gdbarch_pc_regnum (gdbarch),
&optimized, &lval, &addr, &realnum);
frame_register_unwind_location (get_next_frame (this_frame),
gdbarch_pc_regnum (gdbarch),
&optimized, &nlval, &naddr, &nrealnum);
if ((lval == lval_memory && lval == nlval && addr == naddr)
|| (lval == lval_register && lval == nlval && realnum == nrealnum))
{
if (frame_debug)
{
fprintf_unfiltered (gdb_stdlog, "-> ");
fprint_frame (gdb_stdlog, NULL);
fprintf_unfiltered (gdb_stdlog, " // no saved PC }\n");
}
this_frame->stop_reason = UNWIND_NO_SAVED_PC;
this_frame->prev = NULL;
return NULL;
}
}
/* 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 (get_frame_arch (this_frame),
SYMBOL_VALUE_ADDRESS (msymbol),
&current_target);
return maddr == get_frame_func (this_frame);
}
/* Test whether THIS_FRAME is inside the process entry point function. */
static int
inside_entry_func (struct frame_info *this_frame)
{
return (get_frame_func (this_frame) == entry_point_address ());
}
/* 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);
/* tausq/2004-12-07: Dummy frames are skipped because it doesn't make much
sense to stop unwinding at a dummy frame. One place where a dummy
frame may have an address "inside_main_func" is on HPUX. On HPUX, the
pcsqh register (space register for the instruction at the head of the
instruction queue) cannot be written directly; the only way to set it
is to branch to code that is in the target space. In order to implement
frame dummies on HPUX, the called function is made to jump back to where
the inferior was when the user function was called. If gdb was inside
the main function when we created the dummy frame, the dummy frame will
point inside the main function. */
if (this_frame->level >= 0
&& get_frame_type (this_frame) != DUMMY_FRAME
&& !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 the user's backtrace limit has been exceeded, stop. We must
add two to the current level; one of those accounts for backtrace_limit
being 1-based and the level being 0-based, and the other accounts for
the level of the new frame instead of the level of the current
frame. */
if (this_frame->level + 2 > backtrace_limit)
{
frame_debug_got_null_frame (gdb_stdlog, this_frame,
"backtrace limit exceeded");
return NULL;
}
/* 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/2003-07-07: 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: tausq/2004-10-09: this is needed if, for example, the compiler
applied tail-call optimizations to main so that a function called
from main returns directly to the caller of main. Since we don't
stop at main, we should at least stop at the entry point of the
application. */
if (!backtrace_past_entry
&& get_frame_type (this_frame) != 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;
}
/* Assume that the only way to get a zero PC is through something
like a SIGSEGV or a dummy frame, and hence that NORMAL frames
will never unwind a zero PC. */
if (this_frame->level > 0
&& get_frame_type (this_frame) == NORMAL_FRAME
&& get_frame_type (get_next_frame (this_frame)) == NORMAL_FRAME
&& get_frame_pc (this_frame) == 0)
{
frame_debug_got_null_frame (gdb_stdlog, this_frame, "zero PC");
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 that falls within THIS_FRAME's code block. */
CORE_ADDR
get_frame_address_in_block (struct frame_info *this_frame)
{
/* A draft address. */
CORE_ADDR pc = get_frame_pc (this_frame);
struct frame_info *next_frame = this_frame->next;
/* Calling get_frame_pc returns the resume address for THIS_FRAME.
Normally the resume address is inside the body of the function
associated with THIS_FRAME, but there is a special case: when
calling a function which the compiler knows will never return
(for instance abort), the call may be the very last instruction
in the calling function. The resume address will point after the
call and may be at the beginning of a different function
entirely.
If THIS_FRAME is a signal frame or dummy frame, then we should
not adjust the unwound PC. For a dummy frame, GDB pushed the
resume address manually onto the stack. For a signal frame, the
OS may have pushed the resume address manually and invoked the
handler (e.g. GNU/Linux), or invoked the trampoline which called
the signal handler - but in either case the signal handler is
expected to return to the trampoline. So in both of these
cases we know that the resume address is executable and
related. So we only need to adjust the PC if THIS_FRAME
is a normal function.
If the program has been interrupted while THIS_FRAME is current,
then clearly the resume address is inside the associated
function. There are three kinds of interruption: debugger stop
(next frame will be SENTINEL_FRAME), operating system
signal or exception (next frame will be SIGTRAMP_FRAME),
or debugger-induced function call (next frame will be
DUMMY_FRAME). So we only need to adjust the PC if
NEXT_FRAME is a normal function.
We check the type of NEXT_FRAME first, since it is already
known; frame type is determined by the unwinder, and since
we have THIS_FRAME we've already selected an unwinder for
NEXT_FRAME. */
if (get_frame_type (next_frame) == NORMAL_FRAME
&& get_frame_type (this_frame) == NORMAL_FRAME)
return pc - 1;
return pc;
}
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);
/* 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, &fi->prologue_cache);
return fi->base->this_base (fi, &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);
/* 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_locals (fi, &fi->prologue_cache);
return fi->base->this_locals (fi, &fi->base_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);
/* 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_args (fi, &fi->prologue_cache);
return fi->base->this_args (fi, &fi->base_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, &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,
gdb_byte *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, gdb_byte *buf, int len)
{
/* NOTE: target_read_memory returns zero on success! */
return !target_read_memory (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)
{
struct gdbarch *gdbarch = get_frame_arch (this_frame);
/* Normality - an architecture that provides a way of obtaining any
frame inner-most address. */
if (gdbarch_unwind_sp_p (gdbarch))
/* NOTE drow/2008-06-28: gdbarch_unwind_sp could be converted to
operate on THIS_FRAME now. */
return gdbarch_unwind_sp (gdbarch, this_frame->next);
/* Now things are really are grim. Hope that the value returned by
the gdbarch_sp_regnum register is meaningful. */
if (gdbarch_sp_regnum (gdbarch) >= 0)
return get_frame_register_unsigned (this_frame,
gdbarch_sp_regnum (gdbarch));
internal_error (__FILE__, __LINE__, _("Missing unwind SP method"));
}
/* Return the reason why we can't unwind past FRAME. */
enum unwind_stop_reason
get_frame_unwind_stop_reason (struct frame_info *frame)
{
/* If we haven't tried to unwind past this point yet, then assume
that unwinding would succeed. */
if (frame->prev_p == 0)
return UNWIND_NO_REASON;
/* Otherwise, we set a reason when we succeeded (or failed) to
unwind. */
return frame->stop_reason;
}
/* Return a string explaining REASON. */
const char *
frame_stop_reason_string (enum unwind_stop_reason reason)
{
switch (reason)
{
case UNWIND_NULL_ID:
return _("unwinder did not report frame ID");
case UNWIND_INNER_ID:
return _("previous frame inner to this frame (corrupt stack?)");
case UNWIND_SAME_ID:
return _("previous frame identical to this frame (corrupt stack?)");
case UNWIND_NO_SAVED_PC:
return _("frame did not save the PC");
case UNWIND_NO_REASON:
case UNWIND_FIRST_ERROR:
default:
internal_error (__FILE__, __LINE__,
"Invalid frame stop reason");
}
}
/* Clean up after a failed (wrong unwinder) attempt to unwind past
FRAME. */
static void
frame_cleanup_after_sniffer (void *arg)
{
struct frame_info *frame = arg;
/* The sniffer should not allocate a prologue cache if it did not
match this frame. */
gdb_assert (frame->prologue_cache == NULL);
/* No sniffer should extend the frame chain; sniff based on what is
already certain. */
gdb_assert (!frame->prev_p);
/* The sniffer should not check the frame's ID; that's circular. */
gdb_assert (!frame->this_id.p);
/* Clear cached fields dependent on the unwinder.
The previous PC is independent of the unwinder, but the previous
function is not (see get_frame_address_in_block). */
frame->prev_func.p = 0;
frame->prev_func.addr = 0;
/* Discard the unwinder last, so that we can easily find it if an assertion
in this function triggers. */
frame->unwind = NULL;
}
/* Set FRAME's unwinder temporarily, so that we can call a sniffer.
Return a cleanup which should be called if unwinding fails, and
discarded if it succeeds. */
struct cleanup *
frame_prepare_for_sniffer (struct frame_info *frame,
const struct frame_unwind *unwind)
{
gdb_assert (frame->unwind == NULL);
frame->unwind = unwind;
return make_cleanup (frame_cleanup_after_sniffer, frame);
}
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."),
NULL,
show_backtrace_past_main,
&set_backtrace_cmdlist,
&show_backtrace_cmdlist);
add_setshow_boolean_cmd ("past-entry", class_obscure,
&backtrace_past_entry, _("\
Set whether backtraces should continue past the entry point of a program."),
_("\
Show whether backtraces should continue past the entry point of a program."),
_("\
Normally there are no callers beyond the entry point of a program, so GDB\n\
will terminate the backtrace there. Set this variable if you need to see \n\
the rest of the stack trace."),
NULL,
show_backtrace_past_entry,
&set_backtrace_cmdlist,
&show_backtrace_cmdlist);
add_setshow_integer_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."),
NULL,
show_backtrace_limit,
&set_backtrace_cmdlist,
&show_backtrace_cmdlist);
/* Debug this files internals. */
add_setshow_zinteger_cmd ("frame", class_maintenance, &frame_debug, _("\
Set frame debugging."), _("\
Show frame debugging."), _("\
When non-zero, frame specific internal debugging is enabled."),
NULL,
show_frame_debug,
&setdebuglist, &showdebuglist);
}
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