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/* Definitions for a frame unwinder, for GDB, the GNU debugger.
Copyright (C) 2003-2024 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/>. */
#if !defined (FRAME_UNWIND_H)
#define FRAME_UNWIND_H 1
struct frame_data;
class frame_info_ptr;
struct frame_id;
struct frame_unwind;
struct gdbarch;
struct regcache;
struct value;
#include "frame.h"
/* The following unwind functions assume a chain of frames forming the
sequence: (outer) prev <-> this <-> next (inner). All the
functions are called with this frame's `struct frame_info' and
prologue cache.
THIS frame's register values can be obtained by unwinding NEXT
frame's registers (a recursive operation).
THIS frame's prologue cache can be used to cache information such
as where this frame's prologue stores the previous frame's
registers. */
/* Given THIS frame, take a whiff of its registers (namely
the PC and attributes) and if SELF is the applicable unwinder,
return non-zero. Possibly also initialize THIS_PROLOGUE_CACHE; but
only if returning 1. Initializing THIS_PROLOGUE_CACHE in other
cases (0 return) is invalid. In case of exception, the caller has
to set *THIS_PROLOGUE_CACHE to NULL. */
typedef int (frame_sniffer_ftype) (const struct frame_unwind *self,
frame_info_ptr this_frame,
void **this_prologue_cache);
typedef enum unwind_stop_reason (frame_unwind_stop_reason_ftype)
(frame_info_ptr this_frame, void **this_prologue_cache);
/* A default frame sniffer which always accepts the frame. Used by
fallback prologue unwinders. */
int default_frame_sniffer (const struct frame_unwind *self,
frame_info_ptr this_frame,
void **this_prologue_cache);
/* A default stop_reason callback which always claims the frame is
unwindable. */
enum unwind_stop_reason
default_frame_unwind_stop_reason (frame_info_ptr this_frame,
void **this_cache);
/* A default unwind_pc callback that simply unwinds the register identified
by GDBARCH_PC_REGNUM. */
extern CORE_ADDR default_unwind_pc (struct gdbarch *gdbarch,
frame_info_ptr next_frame);
/* A default unwind_sp callback that simply unwinds the register identified
by GDBARCH_SP_REGNUM. */
extern CORE_ADDR default_unwind_sp (struct gdbarch *gdbarch,
frame_info_ptr next_frame);
/* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
use THIS frame, and through it the NEXT frame's register unwind
method, to determine the frame ID of THIS frame.
A frame ID provides an invariant that can be used to re-identify an
instance of a frame. It is a combination of the frame's `base' and
the frame's function's code address.
Traditionally, THIS frame's ID was determined by examining THIS
frame's function's prologue, and identifying the register/offset
used as THIS frame's base.
Example: An examination of THIS frame's prologue reveals that, on
entry, it saves the PC(+12), SP(+8), and R1(+4) registers
(decrementing the SP by 12). Consequently, the frame ID's base can
be determined by adding 12 to the THIS frame's stack-pointer, and
the value of THIS frame's SP can be obtained by unwinding the NEXT
frame's SP.
THIS_PROLOGUE_CACHE can be used to share any prolog analysis data
with the other unwind methods. Memory for that cache should be
allocated using FRAME_OBSTACK_ZALLOC(). */
typedef void (frame_this_id_ftype) (frame_info_ptr this_frame,
void **this_prologue_cache,
struct frame_id *this_id);
/* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
use THIS frame, and implicitly the NEXT frame's register unwind
method, to unwind THIS frame's registers (returning the value of
the specified register REGNUM in the previous frame).
Traditionally, THIS frame's registers were unwound by examining
THIS frame's function's prologue and identifying which registers
that prolog code saved on the stack.
Example: An examination of THIS frame's prologue reveals that, on
entry, it saves the PC(+12), SP(+8), and R1(+4) registers
(decrementing the SP by 12). Consequently, the value of the PC
register in the previous frame is found in memory at SP+12, and
THIS frame's SP can be obtained by unwinding the NEXT frame's SP.
This function takes THIS_FRAME as an argument. It can find the
values of registers in THIS frame by calling get_frame_register
(THIS_FRAME), and reinvoke itself to find other registers in the
PREVIOUS frame by calling frame_unwind_register (THIS_FRAME).
The result is a GDB value object describing the register value. It
may be a lazy reference to memory, a lazy reference to the value of
a register in THIS frame, or a non-lvalue.
If the previous frame's register was not saved by THIS_FRAME and is
therefore undefined, return a wholly optimized-out not_lval value.
THIS_PROLOGUE_CACHE can be used to share any prolog analysis data
with the other unwind methods. Memory for that cache should be
allocated using FRAME_OBSTACK_ZALLOC(). */
typedef struct value * (frame_prev_register_ftype)
(frame_info_ptr this_frame, void **this_prologue_cache,
int regnum);
/* Deallocate extra memory associated with the frame cache if any. */
typedef void (frame_dealloc_cache_ftype) (frame_info *self,
void *this_cache);
/* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
use THIS frame, and implicitly the NEXT frame's register unwind
method, return PREV frame's architecture. */
typedef struct gdbarch *(frame_prev_arch_ftype) (frame_info_ptr this_frame,
void **this_prologue_cache);
struct frame_unwind
{
const char *name;
/* The frame's type. Should this instead be a collection of
predicates that test the frame for various attributes? */
enum frame_type type;
/* Should an attribute indicating the frame's address-in-block go
here? */
frame_unwind_stop_reason_ftype *stop_reason;
frame_this_id_ftype *this_id;
frame_prev_register_ftype *prev_register;
const struct frame_data *unwind_data;
frame_sniffer_ftype *sniffer;
frame_dealloc_cache_ftype *dealloc_cache;
frame_prev_arch_ftype *prev_arch;
};
/* Register a frame unwinder, _prepending_ it to the front of the
search list (so it is sniffed before previously registered
unwinders). By using a prepend, later calls can install unwinders
that override earlier calls. This allows, for instance, an OSABI
to install a more specific sigtramp unwinder that overrides the
traditional brute-force unwinder. */
extern void frame_unwind_prepend_unwinder (struct gdbarch *,
const struct frame_unwind *);
/* Add a frame sniffer to the list. The predicates are polled in the
order that they are appended. The initial list contains the dummy
frame sniffer. */
extern void frame_unwind_append_unwinder (struct gdbarch *gdbarch,
const struct frame_unwind *unwinder);
/* Iterate through sniffers for THIS_FRAME frame until one returns with an
unwinder implementation. THIS_FRAME->UNWIND must be NULL, it will get set
by this function. Possibly initialize THIS_CACHE. */
extern void frame_unwind_find_by_frame (frame_info_ptr this_frame,
void **this_cache);
/* Helper functions for value-based register unwinding. These return
a (possibly lazy) value of the appropriate type. */
/* Return a value which indicates that FRAME did not save REGNUM. */
struct value *frame_unwind_got_optimized (frame_info_ptr frame,
int regnum);
/* Return a value which indicates that FRAME copied REGNUM into
register NEW_REGNUM. */
struct value *frame_unwind_got_register (frame_info_ptr frame, int regnum,
int new_regnum);
/* Return a value which indicates that FRAME saved REGNUM in memory at
ADDR. */
struct value *frame_unwind_got_memory (frame_info_ptr frame, int regnum,
CORE_ADDR addr);
/* Return a value which indicates that FRAME's saved version of
REGNUM has a known constant (computed) value of VAL. */
struct value *frame_unwind_got_constant (frame_info_ptr frame, int regnum,
ULONGEST val);
/* Return a value which indicates that FRAME's saved version of
REGNUM has a known constant (computed) value which is stored
inside BUF. */
struct value *frame_unwind_got_bytes (frame_info_ptr frame, int regnum,
const gdb_byte *buf);
/* Return a value which indicates that FRAME's saved version of REGNUM
has a known constant (computed) value of ADDR. Convert the
CORE_ADDR to a target address if necessary. */
struct value *frame_unwind_got_address (frame_info_ptr frame, int regnum,
CORE_ADDR addr);
#endif
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