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binutils-gdb/gdb/frame.h
Andrew Burgess 9fc501fdfe gdb: Python unwinders, inline frames, and tail-call frames 
This started with me running into the bug described in python/22748,
in summary, if the frame sniffing code accessed any registers within
an inline frame then GDB would crash with this error:

  gdb/frame.c:579: internal-error: frame_id get_frame_id(frame_info*): Assertion `fi->level == 0' failed.

The problem is that, when in the Python unwinder I write this:

  pending_frame.read_register ("register-name")

This is translated internally into a call to `value_of_register',
which in turn becomes a call to `value_of_register_lazy'.

Usually this isn't a problem, `value_of_register_lazy' requires the
next frame (more inner) to have a valid frame_id, which will be the
case (if we're sniffing frame #1, then frame #0 will have had its
frame-id figured out).

Unfortunately if frame #0 is inline within frame #1, then the frame-id
for frame #0 can't be computed until we have the frame-id for #1.  As
a result we can't create a lazy register for frame #1 when frame #0 is
inline.

Initially I proposed a solution inline with that proposed in bugzilla,
changing value_of_register to avoid creating a lazy register value.
However, when this was discussed on the mailing list I got this reply:

  https://sourceware.org/pipermail/gdb-patches/2020-June/169633.html

Which led me to look at these two patches:

  [1] https://sourceware.org/pipermail/gdb-patches/2020-April/167612.html
  [2] https://sourceware.org/pipermail/gdb-patches/2020-April/167930.html

When I considered patches [1] and [2] I saw that all of the issues
being addressed here were related, and that there was a single
solution that could address all of these issues.

First I wrote the new test gdb.opt/inline-frame-tailcall.exp, which
shows that [1] and [2] regress the inline tail-call unwinder, the
reason for this is that these two patches replace a call to
gdbarch_unwind_pc with a call to get_frame_register, however, this is
not correct.  The previous call to gdbarch_unwind_pc takes THIS_FRAME
and returns the $pc value in the previous frame.  In contrast
get_frame_register takes THIS_FRAME and returns the value of the $pc
in THIS_FRAME; these calls are not equivalent.

The reason these patches appear (or do) fix the regressions listed in
[1] is that the tail call sniffer depends on identifying the address
of a caller and a callee, GDB then looks for a tail-call sequence that
takes us from the caller address to the callee, if such a series is
found then tail-call frames are added.

The bug that was being hit, and which was address in patch [1] is that
in order to find the address of the caller, GDB ended up creating a
lazy register value for an inline frame with to frame-id.  The
solution in patch [1] is to instead take the address of the callee and
treat this as the address of the caller.  Getting the address of the
callee works, but we then end up looking for a tail-call series from
the callee to the callee, which obviously doesn't return any sane
results, so we don't insert any tail call frames.

The original patch [1] did cause some breakage, so patch [2] undid
patch [1] in all cases except those where we had an inline frame with
no frame-id.  It just so happens that there were no tests that fitted
this description _and_ which required tail-call frames to be
successfully spotted, as a result patch [2] appeared to work.

The new test inline-frame-tailcall.exp, exposes the flaw in patch [2].

This commit undoes patch [1] and [2], and replaces them with a new
solution, which is also different to the solution proposed in the
python/22748 bug report.

In this solution I propose that we introduce some special case logic
to value_of_register_lazy.  To understand what this logic is we must
first look at how inline frames unwind registers, this is very simple,
they do this:

  static struct value *
  inline_frame_prev_register (struct frame_info *this_frame,
                              void **this_cache, int regnum)
  {
    return get_frame_register_value (this_frame, regnum);
  }

And remember:

  struct value *
  get_frame_register_value (struct frame_info *frame, int regnum)
  {
    return frame_unwind_register_value (frame->next, regnum);
  }

So in all cases, unwinding a register in an inline frame just asks the
next frame to unwind the register, this makes sense, as an inline
frame doesn't really exist, when we unwind a register in an inline
frame, we're really just asking the next frame for the value of the
register in the previous, non-inline frame.

So, if we assume that we only get into the missing frame-id situation
when we try to unwind a register from an inline frame during the frame
sniffing process, then we can change value_of_register_lazy to not
create lazy register values for an inline frame.

Imagine this stack setup, where #1 is inline within #2.

  #3 -> #2 -> #1 -> #0
        \______/
         inline

Now when trying to figure out the frame-id for #1, we need to compute
the frame-id for #2.  If the frame sniffer for #2 causes a lazy
register read in #2, either due to a Python Unwinder, or for the
tail-call sniffer, then we call value_of_register_lazy passing in
frame #2.

In value_of_register_lazy, we grab the next frame, which is #1, and we
used to then ask for the frame-id of #1, which was not computed, and
this was our bug.

Now, I propose we spot that #1 is an inline frame, and so lookup the
next frame of #1, which is #0.  As #0 is not inline it will have a
valid frame-id, and so we create a lazy register value using #0 as the
next-frame-id.  This will give us the exact same result we had
previously (thanks to the code we inspected above).

Encoding into value_of_register_lazy the knowledge that reading an
inline frame register will always just forward to the next frame
feels.... not ideal, but this seems like the cleanest solution to this
recursive frame-id computation/sniffing issue that appears to crop
up.

The following two commits are fully reverted with this commit, these
correspond to patches [1] and [2] respectively:

  commit 5939967b35
  Date:   Tue Apr 14 17:26:22 2020 -0300

      Fix inline frame unwinding breakage

  commit 991a3e2e99
  Date:   Sat Apr 25 00:32:44 2020 -0300

      Fix remaining inline/tailcall unwinding breakage for x86_64

gdb/ChangeLog:

	PR python/22748
	* dwarf2/frame-tailcall.c (dwarf2_tailcall_sniffer_first): Remove
	special handling for inline frames.
	* findvar.c (value_of_register_lazy): Skip inline frames when
	creating lazy register values.
	* frame.c (frame_id_computed_p): Delete definition.
	* frame.h (frame_id_computed_p): Delete declaration.

gdb/testsuite/ChangeLog:

	PR python/22748
	* gdb.opt/inline-frame-tailcall.c: New file.
	* gdb.opt/inline-frame-tailcall.exp: New file.
	* gdb.python/py-unwind-inline.c: New file.
	* gdb.python/py-unwind-inline.exp: New file.
	* gdb.python/py-unwind-inline.py: New file.
2020-07-06 15:06:07 +01:00

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/* Definitions for dealing with stack frames, for GDB, the GNU debugger.
Copyright (C) 1986-2020 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_H)
#define FRAME_H 1
/* The following is the intended naming schema for frame functions.
It isn't 100% consistent, but it is approaching that. Frame naming
schema:
Prefixes:
get_frame_WHAT...(): Get WHAT from the THIS frame (functionally
equivalent to THIS->next->unwind->what)
frame_unwind_WHAT...(): Unwind THIS frame's WHAT from the NEXT
frame.
frame_unwind_caller_WHAT...(): Unwind WHAT for NEXT stack frame's
real caller. Any inlined functions in NEXT's stack frame are
skipped. Use these to ignore any potentially inlined functions,
e.g. inlined into the first instruction of a library trampoline.
get_stack_frame_WHAT...(): Get WHAT for THIS frame, but if THIS is
inlined, skip to the containing stack frame.
put_frame_WHAT...(): Put a value into this frame (unsafe, need to
invalidate the frame / regcache afterwards) (better name more
strongly hinting at its unsafeness)
safe_....(): Safer version of various functions, doesn't throw an
error (leave this for later?). Returns non-zero / non-NULL if the
request succeeds, zero / NULL otherwize.
Suffixes:
void /frame/_WHAT(): Read WHAT's value into the buffer parameter.
ULONGEST /frame/_WHAT_unsigned(): Return an unsigned value (the
alternative is *frame_unsigned_WHAT).
LONGEST /frame/_WHAT_signed(): Return WHAT signed value.
What:
/frame/_memory* (frame, coreaddr, len [, buf]): Extract/return
*memory.
/frame/_register* (frame, regnum [, buf]): extract/return register.
CORE_ADDR /frame/_{pc,sp,...} (frame): Resume address, innner most
stack *address, ...
*/
#include "language.h"
#include "cli/cli-option.h"
struct symtab_and_line;
struct frame_unwind;
struct frame_base;
struct block;
struct gdbarch;
struct ui_file;
struct ui_out;
struct frame_print_options;
/* Status of a given frame's stack. */
enum frame_id_stack_status
{
/* Stack address is invalid. E.g., this frame is the outermost
(i.e., _start), and the stack hasn't been setup yet. */
FID_STACK_INVALID = 0,
/* Stack address is valid, and is found in the stack_addr field. */
FID_STACK_VALID = 1,
/* Sentinel frame. */
FID_STACK_SENTINEL = 2,
/* Stack address is unavailable. I.e., there's a valid stack, but
we don't know where it is (because memory or registers we'd
compute it from were not collected). */
FID_STACK_UNAVAILABLE = -1
};
/* The frame object. */
struct frame_info;
/* The frame object's ID. This provides a per-frame unique identifier
that can be used to relocate a `struct frame_info' after a target
resume or a frame cache destruct. It of course assumes that the
inferior hasn't unwound the stack past that frame. */
struct frame_id
{
/* The frame's stack address. This shall be constant through out
the lifetime of a frame. Note that this requirement applies to
not just the function body, but also the prologue and (in theory
at least) the epilogue. Since that value needs to fall either on
the boundary, or within the frame's address range, the frame's
outer-most address (the inner-most address of the previous frame)
is used. Watch out for all the legacy targets that still use the
function pointer register or stack pointer register. They are
wrong.
This field is valid only if frame_id.stack_status is
FID_STACK_VALID. It will be 0 for other
FID_STACK_... statuses. */
CORE_ADDR stack_addr;
/* The frame's code address. This shall be constant through out the
lifetime of the frame. While the PC (a.k.a. resume address)
changes as the function is executed, this code address cannot.
Typically, it is set to the address of the entry point of the
frame's function (as returned by get_frame_func).
For inlined functions (INLINE_DEPTH != 0), this is the address of
the first executed instruction in the block corresponding to the
inlined function.
This field is valid only if code_addr_p is true. Otherwise, this
frame is considered to have a wildcard code address, i.e. one that
matches every address value in frame comparisons. */
CORE_ADDR code_addr;
/* The frame's special address. This shall be constant through out the
lifetime of the frame. This is used for architectures that may have
frames that do not change the stack but are still distinct and have
some form of distinct identifier (e.g. the ia64 which uses a 2nd
stack for registers). This field is treated as unordered - i.e. will
not be used in frame ordering comparisons.
This field is valid only if special_addr_p is true. Otherwise, this
frame is considered to have a wildcard special address, i.e. one that
matches every address value in frame comparisons. */
CORE_ADDR special_addr;
/* Flags to indicate the above fields have valid contents. */
ENUM_BITFIELD(frame_id_stack_status) stack_status : 3;
unsigned int code_addr_p : 1;
unsigned int special_addr_p : 1;
/* It is non-zero for a frame made up by GDB without stack data
representation in inferior, such as INLINE_FRAME or TAILCALL_FRAME.
Caller of inlined function will have it zero, each more inner called frame
will have it increasingly one, two etc. Similarly for TAILCALL_FRAME. */
int artificial_depth;
};
/* Save and restore the currently selected frame. */
class scoped_restore_selected_frame
{
public:
/* Save the currently selected frame. */
scoped_restore_selected_frame ();
/* Restore the currently selected frame. */
~scoped_restore_selected_frame ();
DISABLE_COPY_AND_ASSIGN (scoped_restore_selected_frame);
private:
/* The ID of the previously selected frame. */
struct frame_id m_fid;
};
/* Methods for constructing and comparing Frame IDs. */
/* For convenience. All fields are zero. This means "there is no frame". */
extern const struct frame_id null_frame_id;
/* Sentinel frame. */
extern const struct frame_id sentinel_frame_id;
/* This means "there is no frame ID, but there is a frame". It should be
replaced by best-effort frame IDs for the outermost frame, somehow.
The implementation is only special_addr_p set. */
extern const struct frame_id outer_frame_id;
/* Flag to control debugging. */
extern unsigned int frame_debug;
/* Construct a frame ID. The first parameter is the frame's constant
stack address (typically the outer-bound), and the second the
frame's constant code address (typically the entry point).
The special identifier address is set to indicate a wild card. */
extern struct frame_id frame_id_build (CORE_ADDR stack_addr,
CORE_ADDR code_addr);
/* Construct a special frame ID. The first parameter is the frame's constant
stack address (typically the outer-bound), the second is the
frame's constant code address (typically the entry point),
and the third parameter is the frame's special identifier address. */
extern struct frame_id frame_id_build_special (CORE_ADDR stack_addr,
CORE_ADDR code_addr,
CORE_ADDR special_addr);
/* Construct a frame ID representing a frame where the stack address
exists, but is unavailable. CODE_ADDR is the frame's constant code
address (typically the entry point). The special identifier
address is set to indicate a wild card. */
extern struct frame_id frame_id_build_unavailable_stack (CORE_ADDR code_addr);
/* Construct a frame ID representing a frame where the stack address
exists, but is unavailable. CODE_ADDR is the frame's constant code
address (typically the entry point). SPECIAL_ADDR is the special
identifier address. */
extern struct frame_id
frame_id_build_unavailable_stack_special (CORE_ADDR code_addr,
CORE_ADDR special_addr);
/* Construct a wild card frame ID. The parameter is the frame's constant
stack address (typically the outer-bound). The code address as well
as the special identifier address are set to indicate wild cards. */
extern struct frame_id frame_id_build_wild (CORE_ADDR stack_addr);
/* Returns non-zero when L is a valid frame (a valid frame has a
non-zero .base). The outermost frame is valid even without an
ID. */
extern int frame_id_p (struct frame_id l);
/* Returns non-zero when L is a valid frame representing a frame made up by GDB
without stack data representation in inferior, such as INLINE_FRAME or
TAILCALL_FRAME. */
extern int frame_id_artificial_p (struct frame_id l);
/* Returns non-zero when L and R identify the same frame, or, if
either L or R have a zero .func, then the same frame base. */
extern int frame_id_eq (struct frame_id l, struct frame_id r);
/* Write the internal representation of a frame ID on the specified
stream. */
extern void fprint_frame_id (struct ui_file *file, struct frame_id id);
/* Frame types. Some are real, some are signal trampolines, and some
are completely artificial (dummy). */
enum frame_type
{
/* A true stack frame, created by the target program during normal
execution. */
NORMAL_FRAME,
/* A fake frame, created by GDB when performing an inferior function
call. */
DUMMY_FRAME,
/* A frame representing an inlined function, associated with an
upcoming (prev, outer, older) NORMAL_FRAME. */
INLINE_FRAME,
/* A virtual frame of a tail call - see dwarf2_tailcall_frame_unwind. */
TAILCALL_FRAME,
/* In a signal handler, various OSs handle this in various ways.
The main thing is that the frame may be far from normal. */
SIGTRAMP_FRAME,
/* Fake frame representing a cross-architecture call. */
ARCH_FRAME,
/* Sentinel or registers frame. This frame obtains register values
direct from the inferior's registers. */
SENTINEL_FRAME
};
/* For every stopped thread, GDB tracks two frames: current and
selected. Current frame is the inner most frame of the selected
thread. Selected frame is the one being examined by the GDB
CLI (selected using `up', `down', ...). The frames are created
on-demand (via get_prev_frame()) and then held in a frame cache. */
/* FIXME: cagney/2002-11-28: Er, there is a lie here. If you do the
sequence: `thread 1; up; thread 2; thread 1' you lose thread 1's
selected frame. At present GDB only tracks the selected frame of
the current thread. But be warned, that might change. */
/* FIXME: cagney/2002-11-14: At any time, only one thread's selected
and current frame can be active. Switching threads causes gdb to
discard all that cached frame information. Ulgh! Instead, current
and selected frame should be bound to a thread. */
/* On demand, create the inner most frame using information found in
the inferior. If the inner most frame can't be created, throw an
error. */
extern struct frame_info *get_current_frame (void);
/* Does the current target interface have enough state to be able to
query the current inferior for frame info, and is the inferior in a
state where that is possible? */
extern int has_stack_frames (void);
/* Invalidates the frame cache (this function should have been called
invalidate_cached_frames).
FIXME: cagney/2002-11-28: There should be two methods: one that
reverts the thread's selected frame back to current frame (for when
the inferior resumes) and one that does not (for when the user
modifies the target invalidating the frame cache). */
extern void reinit_frame_cache (void);
/* On demand, create the selected frame and then return it. If the
selected frame can not be created, this function prints then throws
an error. When MESSAGE is non-NULL, use it for the error message,
otherwize use a generic error message. */
/* FIXME: cagney/2002-11-28: At present, when there is no selected
frame, this function always returns the current (inner most) frame.
It should instead, when a thread has previously had its frame
selected (but not resumed) and the frame cache invalidated, find
and then return that thread's previously selected frame. */
extern struct frame_info *get_selected_frame (const char *message);
/* If there is a selected frame, return it. Otherwise, return NULL. */
extern struct frame_info *get_selected_frame_if_set (void);
/* Select a specific frame. NULL, apparently implies re-select the
inner most frame. */
extern void select_frame (struct frame_info *);
/* Given a FRAME, return the next (more inner, younger) or previous
(more outer, older) frame. */
extern struct frame_info *get_prev_frame (struct frame_info *);
extern struct frame_info *get_next_frame (struct frame_info *);
/* Like get_next_frame(), but allows return of the sentinel frame. NULL
is never returned. */
extern struct frame_info *get_next_frame_sentinel_okay (struct frame_info *);
/* 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. */
extern struct frame_info *get_prev_frame_always (struct frame_info *);
/* Given a frame's ID, relocate the frame. Returns NULL if the frame
is not found. */
extern struct frame_info *frame_find_by_id (struct frame_id id);
/* Given a frame's ID, find the previous frame's ID. Returns null_frame_id
if the frame is not found. */
extern struct frame_id get_prev_frame_id_by_id (struct frame_id id);
/* Base attributes of a frame: */
/* The frame's `resume' address. Where the program will resume in
this frame.
This replaced: frame->pc; */
extern CORE_ADDR get_frame_pc (struct frame_info *);
/* Same as get_frame_pc, but return a boolean indication of whether
the PC is actually available, instead of throwing an error. */
extern int get_frame_pc_if_available (struct frame_info *frame,
CORE_ADDR *pc);
/* An address (not necessarily aligned to an instruction boundary)
that falls within THIS frame's code block.
When a function call is the last statement in a block, the return
address for the call may land at the start of the next block.
Similarly, if a no-return function call is the last statement in
the function, the return address may end up pointing beyond the
function, and possibly at the start of the next function.
These methods make an allowance for this. For call frames, this
function returns the frame's PC-1 which "should" be an address in
the frame's block. */
extern CORE_ADDR get_frame_address_in_block (struct frame_info *this_frame);
/* Same as get_frame_address_in_block, but returns a boolean
indication of whether the frame address is determinable (when the
PC is unavailable, it will not be), instead of possibly throwing an
error trying to read an unavailable PC. */
extern int
get_frame_address_in_block_if_available (struct frame_info *this_frame,
CORE_ADDR *pc);
/* The frame's inner-most bound. AKA the stack-pointer. Confusingly
known as top-of-stack. */
extern CORE_ADDR get_frame_sp (struct frame_info *);
/* Following on from the `resume' address. Return the entry point
address of the function containing that resume address, or zero if
that function isn't known. */
extern CORE_ADDR get_frame_func (struct frame_info *fi);
/* Same as get_frame_func, but returns a boolean indication of whether
the frame function is determinable (when the PC is unavailable, it
will not be), instead of possibly throwing an error trying to read
an unavailable PC. */
extern int get_frame_func_if_available (struct frame_info *fi, CORE_ADDR *);
/* Closely related to the resume address, various symbol table
attributes that are determined by the PC. Note that for a normal
frame, the PC refers to the resume address after the return, and
not the call instruction. In such a case, the address is adjusted
so that it (approximately) identifies the call site (and not the
return site).
NOTE: cagney/2002-11-28: The frame cache could be used to cache the
computed value. Working on the assumption that the bottle-neck is
in the single step code, and that code causes the frame cache to be
constantly flushed, caching things in a frame is probably of little
benefit. As they say `show us the numbers'.
NOTE: cagney/2002-11-28: Plenty more where this one came from:
find_frame_block(), find_frame_partial_function(),
find_frame_symtab(), find_frame_function(). Each will need to be
carefully considered to determine if the real intent was for it to
apply to the PC or the adjusted PC. */
extern symtab_and_line find_frame_sal (frame_info *frame);
/* Set the current source and line to the location given by frame
FRAME, if possible. */
void set_current_sal_from_frame (struct frame_info *);
/* Return the frame base (what ever that is) (DEPRECATED).
Old code was trying to use this single method for two conflicting
purposes. Such code needs to be updated to use either of:
get_frame_id: A low level frame unique identifier, that consists of
both a stack and a function address, that can be used to uniquely
identify a frame. This value is determined by the frame's
low-level unwinder, the stack part [typically] being the
top-of-stack of the previous frame, and the function part being the
function's start address. Since the correct identification of a
frameless function requires both a stack and function address,
the old get_frame_base method was not sufficient.
get_frame_base_address: get_frame_locals_address:
get_frame_args_address: A set of high-level debug-info dependant
addresses that fall within the frame. These addresses almost
certainly will not match the stack address part of a frame ID (as
returned by get_frame_base).
This replaced: frame->frame; */
extern CORE_ADDR get_frame_base (struct frame_info *);
/* Return the per-frame unique identifer. Can be used to relocate a
frame after a frame cache flush (and other similar operations). If
FI is NULL, return the null_frame_id.
NOTE: kettenis/20040508: These functions return a structure. On
platforms where structures are returned in static storage (vax,
m68k), this may trigger compiler bugs in code like:
if (frame_id_eq (get_frame_id (l), get_frame_id (r)))
where the return value from the first get_frame_id (l) gets
overwritten by the second get_frame_id (r). Please avoid writing
code like this. Use code like:
struct frame_id id = get_frame_id (l);
if (frame_id_eq (id, get_frame_id (r)))
instead, since that avoids the bug. */
extern struct frame_id get_frame_id (struct frame_info *fi);
extern struct frame_id get_stack_frame_id (struct frame_info *fi);
extern struct frame_id frame_unwind_caller_id (struct frame_info *next_frame);
/* Assuming that a frame is `normal', return its base-address, or 0 if
the information isn't available. NOTE: This address is really only
meaningful to the frame's high-level debug info. */
extern CORE_ADDR get_frame_base_address (struct frame_info *);
/* Assuming that a frame is `normal', return the base-address of the
local variables, or 0 if the information isn't available. NOTE:
This address is really only meaningful to the frame's high-level
debug info. Typically, the argument and locals share a single
base-address. */
extern CORE_ADDR get_frame_locals_address (struct frame_info *);
/* Assuming that a frame is `normal', return the base-address of the
parameter list, or 0 if that information isn't available. NOTE:
This address is really only meaningful to the frame's high-level
debug info. Typically, the argument and locals share a single
base-address. */
extern CORE_ADDR get_frame_args_address (struct frame_info *);
/* The frame's level: 0 for innermost, 1 for its caller, ...; or -1
for an invalid frame). */
extern int frame_relative_level (struct frame_info *fi);
/* Return the frame's type. */
extern enum frame_type get_frame_type (struct frame_info *);
/* Return the frame's program space. */
extern struct program_space *get_frame_program_space (struct frame_info *);
/* Unwind THIS frame's program space from the NEXT frame. */
extern struct program_space *frame_unwind_program_space (struct frame_info *);
class address_space;
/* Return the frame's address space. */
extern const address_space *get_frame_address_space (struct frame_info *);
/* For frames where we can not unwind further, describe why. */
enum unwind_stop_reason
{
#define SET(name, description) name,
#define FIRST_ENTRY(name) UNWIND_FIRST = name,
#define LAST_ENTRY(name) UNWIND_LAST = name,
#define FIRST_ERROR(name) UNWIND_FIRST_ERROR = name,
#include "unwind_stop_reasons.def"
#undef SET
#undef FIRST_ENTRY
#undef LAST_ENTRY
#undef FIRST_ERROR
};
/* Return the reason why we can't unwind past this frame. */
enum unwind_stop_reason get_frame_unwind_stop_reason (struct frame_info *);
/* Translate a reason code to an informative string. This converts the
generic stop reason codes into a generic string describing the code.
For a possibly frame specific string explaining the stop reason, use
FRAME_STOP_REASON_STRING instead. */
const char *unwind_stop_reason_to_string (enum unwind_stop_reason);
/* Return a possibly frame specific string explaining why the unwind
stopped here. E.g., if unwinding tripped on a memory error, this
will return the error description string, which includes the address
that we failed to access. If there's no specific reason stored for
a frame then a generic reason string will be returned.
Should only be called for frames that don't have a previous frame. */
const char *frame_stop_reason_string (struct frame_info *);
/* Unwind the stack frame so that the value of REGNUM, in the previous
(up, older) frame is returned. If VALUEP is NULL, don't
fetch/compute the value. Instead just return the location of the
value. */
extern void frame_register_unwind (frame_info *frame, int regnum,
int *optimizedp, int *unavailablep,
enum lval_type *lvalp,
CORE_ADDR *addrp, int *realnump,
gdb_byte *valuep);
/* Fetch a register from this, or unwind a register from the next
frame. Note that the get_frame methods are wrappers to
frame->next->unwind. They all [potentially] throw an error if the
fetch fails. The value methods never return NULL, but usually
do return a lazy value. */
extern void frame_unwind_register (frame_info *next_frame,
int regnum, gdb_byte *buf);
extern void get_frame_register (struct frame_info *frame,
int regnum, gdb_byte *buf);
struct value *frame_unwind_register_value (frame_info *next_frame,
int regnum);
struct value *get_frame_register_value (struct frame_info *frame,
int regnum);
extern LONGEST frame_unwind_register_signed (frame_info *next_frame,
int regnum);
extern LONGEST get_frame_register_signed (struct frame_info *frame,
int regnum);
extern ULONGEST frame_unwind_register_unsigned (frame_info *frame,
int regnum);
extern ULONGEST get_frame_register_unsigned (struct frame_info *frame,
int regnum);
/* Read a register from this, or unwind a register from the next
frame. Note that the read_frame methods are wrappers to
get_frame_register_value, that do not throw if the result is
optimized out or unavailable. */
extern int read_frame_register_unsigned (struct frame_info *frame,
int regnum, ULONGEST *val);
/* Get the value of the register that belongs to this FRAME. This
function is a wrapper to the call sequence ``frame_register_unwind
(get_next_frame (FRAME))''. As per frame_register_unwind(), if
VALUEP is NULL, the registers value is not fetched/computed. */
extern void frame_register (struct frame_info *frame, int regnum,
int *optimizedp, int *unavailablep,
enum lval_type *lvalp,
CORE_ADDR *addrp, int *realnump,
gdb_byte *valuep);
/* The reverse. Store a register value relative to the specified
frame. Note: this call makes the frame's state undefined. The
register and frame caches must be flushed. */
extern void put_frame_register (struct frame_info *frame, int regnum,
const gdb_byte *buf);
/* Read LEN bytes from one or multiple registers starting with REGNUM
in frame FRAME, starting at OFFSET, into BUF. If the register
contents are optimized out or unavailable, set *OPTIMIZEDP,
*UNAVAILABLEP accordingly. */
extern int get_frame_register_bytes (struct frame_info *frame, int regnum,
CORE_ADDR offset, int len,
gdb_byte *myaddr,
int *optimizedp, int *unavailablep);
/* Write LEN bytes to one or multiple registers starting with REGNUM
in frame FRAME, starting at OFFSET, into BUF. */
extern void put_frame_register_bytes (struct frame_info *frame, int regnum,
CORE_ADDR offset, int len,
const gdb_byte *myaddr);
/* Unwind the PC. Strictly speaking return the resume address of the
calling frame. For GDB, `pc' is the resume address and not a
specific register. */
extern CORE_ADDR frame_unwind_caller_pc (struct frame_info *frame);
/* Discard the specified frame. Restoring the registers to the state
of the caller. */
extern void frame_pop (struct frame_info *frame);
/* Return memory from the specified frame. A frame knows its thread /
LWP and hence can find its way down to a target. The assumption
here is that the current and previous frame share a common address
space.
If the memory read fails, these methods throw an error.
NOTE: cagney/2003-06-03: Should there be unwind versions of these
methods? That isn't clear. Can code, for instance, assume that
this and the previous frame's memory or architecture are identical?
If architecture / memory changes are always separated by special
adaptor frames this should be ok. */
extern void get_frame_memory (struct frame_info *this_frame, CORE_ADDR addr,
gdb_byte *buf, int len);
extern LONGEST get_frame_memory_signed (struct frame_info *this_frame,
CORE_ADDR memaddr, int len);
extern ULONGEST get_frame_memory_unsigned (struct frame_info *this_frame,
CORE_ADDR memaddr, int len);
/* Same as above, but return non-zero when the entire memory read
succeeds, zero otherwize. */
extern int safe_frame_unwind_memory (struct frame_info *this_frame,
CORE_ADDR addr, gdb_byte *buf, int len);
/* Return this frame's architecture. */
extern struct gdbarch *get_frame_arch (struct frame_info *this_frame);
/* Return the previous frame's architecture. */
extern struct gdbarch *frame_unwind_arch (frame_info *next_frame);
/* Return the previous frame's architecture, skipping inline functions. */
extern struct gdbarch *frame_unwind_caller_arch (struct frame_info *frame);
/* Values for the source flag to be used in print_frame_info ().
For all the cases below, the address is never printed if
'set print address' is off. When 'set print address' is on,
the address is printed if the program counter is not at the
beginning of the source line of the frame
and PRINT_WHAT is != LOC_AND_ADDRESS. */
enum print_what
{
/* Print only the address, source line, like in stepi. */
SRC_LINE = -1,
/* Print only the location, i.e. level, address,
function, args (as controlled by 'set print frame-arguments'),
file, line, line num. */
LOCATION,
/* Print both of the above. */
SRC_AND_LOC,
/* Print location only, print the address even if the program counter
is at the beginning of the source line. */
LOC_AND_ADDRESS,
/* Print only level and function,
i.e. location only, without address, file, line, line num. */
SHORT_LOCATION
};
/* Allocate zero initialized memory from the frame cache obstack.
Appendices to the frame info (such as the unwind cache) should
allocate memory using this method. */
extern void *frame_obstack_zalloc (unsigned long size);
#define FRAME_OBSTACK_ZALLOC(TYPE) \
((TYPE *) frame_obstack_zalloc (sizeof (TYPE)))
#define FRAME_OBSTACK_CALLOC(NUMBER,TYPE) \
((TYPE *) frame_obstack_zalloc ((NUMBER) * sizeof (TYPE)))
class readonly_detached_regcache;
/* Create a regcache, and copy the frame's registers into it. */
std::unique_ptr<readonly_detached_regcache> frame_save_as_regcache
(struct frame_info *this_frame);
extern const struct block *get_frame_block (struct frame_info *,
CORE_ADDR *addr_in_block);
/* Return the `struct block' that belongs to the selected thread's
selected frame. If the inferior has no state, return NULL.
NOTE: cagney/2002-11-29:
No state? Does the inferior have any execution state (a core file
does, an executable does not). At present the code tests
`target_has_stack' but I'm left wondering if it should test
`target_has_registers' or, even, a merged target_has_state.
Should it look at the most recently specified SAL? If the target
has no state, should this function try to extract a block from the
most recently selected SAL? That way `list foo' would give it some
sort of reference point. Then again, perhaps that would confuse
things.
Calls to this function can be broken down into two categories: Code
that uses the selected block as an additional, but optional, data
point; Code that uses the selected block as a prop, when it should
have the relevant frame/block/pc explicitly passed in.
The latter can be eliminated by correctly parameterizing the code,
the former though is more interesting. Per the "address" command,
it occurs in the CLI code and makes it possible for commands to
work, even when the inferior has no state. */
extern const struct block *get_selected_block (CORE_ADDR *addr_in_block);
extern struct symbol *get_frame_function (struct frame_info *);
extern CORE_ADDR get_pc_function_start (CORE_ADDR);
extern struct frame_info *find_relative_frame (struct frame_info *, int *);
/* Wrapper over print_stack_frame modifying current_uiout with UIOUT for
the function call. */
extern void print_stack_frame_to_uiout (struct ui_out *uiout,
struct frame_info *, int print_level,
enum print_what print_what,
int set_current_sal);
extern void print_stack_frame (struct frame_info *, int print_level,
enum print_what print_what,
int set_current_sal);
extern void print_frame_info (const frame_print_options &fp_opts,
struct frame_info *, int print_level,
enum print_what print_what, int args,
int set_current_sal);
extern struct frame_info *block_innermost_frame (const struct block *);
extern int deprecated_frame_register_read (struct frame_info *frame, int regnum,
gdb_byte *buf);
/* From stack.c. */
/* The possible choices of "set print frame-arguments". */
extern const char print_frame_arguments_all[];
extern const char print_frame_arguments_scalars[];
extern const char print_frame_arguments_none[];
/* The possible choices of "set print frame-info". */
extern const char print_frame_info_auto[];
extern const char print_frame_info_source_line[];
extern const char print_frame_info_location[];
extern const char print_frame_info_source_and_location[];
extern const char print_frame_info_location_and_address[];
extern const char print_frame_info_short_location[];
/* The possible choices of "set print entry-values". */
extern const char print_entry_values_no[];
extern const char print_entry_values_only[];
extern const char print_entry_values_preferred[];
extern const char print_entry_values_if_needed[];
extern const char print_entry_values_both[];
extern const char print_entry_values_compact[];
extern const char print_entry_values_default[];
/* Data for the frame-printing "set print" settings exposed as command
options. */
struct frame_print_options
{
const char *print_frame_arguments = print_frame_arguments_scalars;
const char *print_frame_info = print_frame_info_auto;
const char *print_entry_values = print_entry_values_default;
/* If true, don't invoke pretty-printers for frame
arguments. */
bool print_raw_frame_arguments;
};
/* The values behind the global "set print ..." settings. */
extern frame_print_options user_frame_print_options;
/* Inferior function parameter value read in from a frame. */
struct frame_arg
{
/* Symbol for this parameter used for example for its name. */
struct symbol *sym = nullptr;
/* Value of the parameter. It is NULL if ERROR is not NULL; if both VAL and
ERROR are NULL this parameter's value should not be printed. */
struct value *val = nullptr;
/* String containing the error message, it is more usually NULL indicating no
error occured reading this parameter. */
gdb::unique_xmalloc_ptr<char> error;
/* One of the print_entry_values_* entries as appropriate specifically for
this frame_arg. It will be different from print_entry_values. With
print_entry_values_no this frame_arg should be printed as a normal
parameter. print_entry_values_only says it should be printed as entry
value parameter. print_entry_values_compact says it should be printed as
both as a normal parameter and entry values parameter having the same
value - print_entry_values_compact is not permitted fi ui_out_is_mi_like_p
(in such case print_entry_values_no and print_entry_values_only is used
for each parameter kind specifically. */
const char *entry_kind = nullptr;
};
extern void read_frame_arg (const frame_print_options &fp_opts,
symbol *sym, frame_info *frame,
struct frame_arg *argp,
struct frame_arg *entryargp);
extern void read_frame_local (struct symbol *sym, struct frame_info *frame,
struct frame_arg *argp);
extern void info_args_command (const char *, int);
extern void info_locals_command (const char *, int);
extern void return_command (const char *, int);
/* Set FRAME's unwinder temporarily, so that we can call a sniffer.
If sniffing fails, the caller should be sure to call
frame_cleanup_after_sniffer. */
extern void frame_prepare_for_sniffer (struct frame_info *frame,
const struct frame_unwind *unwind);
/* Clean up after a failed (wrong unwinder) attempt to unwind past
FRAME. */
extern void frame_cleanup_after_sniffer (struct frame_info *frame);
/* Notes (cagney/2002-11-27, drow/2003-09-06):
You might think that calls to this function can simply be replaced by a
call to get_selected_frame().
Unfortunately, it isn't that easy.
The relevant code needs to be audited to determine if it is
possible (or practical) to instead pass the applicable frame in as a
parameter. For instance, DEPRECATED_DO_REGISTERS_INFO() relied on
the deprecated_selected_frame global, while its replacement,
PRINT_REGISTERS_INFO(), is parameterized with the selected frame.
The only real exceptions occur at the edge (in the CLI code) where
user commands need to pick up the selected frame before proceeding.
There are also some functions called with a NULL frame meaning either "the
program is not running" or "use the selected frame".
This is important. GDB is trying to stamp out the hack:
saved_frame = deprecated_safe_get_selected_frame ();
select_frame (...);
hack_using_global_selected_frame ();
select_frame (saved_frame);
Take care!
This function calls get_selected_frame if the inferior should have a
frame, or returns NULL otherwise. */
extern struct frame_info *deprecated_safe_get_selected_frame (void);
/* Create a frame using the specified BASE and PC. */
extern struct frame_info *create_new_frame (CORE_ADDR base, CORE_ADDR pc);
/* Return true if the frame unwinder for frame FI is UNWINDER; false
otherwise. */
extern int frame_unwinder_is (struct frame_info *fi,
const struct frame_unwind *unwinder);
/* Return the language of FRAME. */
extern enum language get_frame_language (struct frame_info *frame);
/* Return the first non-tailcall frame above FRAME or FRAME if it is not a
tailcall frame. Return NULL if FRAME is the start of a tailcall-only
chain. */
extern struct frame_info *skip_tailcall_frames (struct frame_info *frame);
/* Return the first frame above FRAME or FRAME of which the code is
writable. */
extern struct frame_info *skip_unwritable_frames (struct frame_info *frame);
/* Data for the "set backtrace" settings. */
struct set_backtrace_options
{
/* Flag to indicate whether backtraces should continue past
main. */
bool backtrace_past_main = false;
/* Flag to indicate whether backtraces should continue past
entry. */
bool backtrace_past_entry = false;
/* Upper bound on the number of backtrace levels. Note this is not
exposed as a command option, because "backtrace" and "frame
apply" already have other means to set a frame count limit. */
unsigned int backtrace_limit = UINT_MAX;
};
/* The corresponding option definitions. */
extern const gdb::option::option_def set_backtrace_option_defs[2];
/* The values behind the global "set backtrace ..." settings. */
extern set_backtrace_options user_set_backtrace_options;
/* Mark that the PC value is masked for the previous frame. */
extern void set_frame_previous_pc_masked (struct frame_info *frame);
/* Get whether the PC value is masked for the given frame. */
extern bool get_frame_pc_masked (const struct frame_info *frame);
#endif /* !defined (FRAME_H) */
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