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Re: [PATCH v5] Add Guile frame unwinder interface
- From: Doug Evans <xdje42 at gmail dot com>
- To: Andy Wingo <wingo at igalia dot com>
- Cc: gdb-patches at sourceware dot org
- Date: Mon, 27 Apr 2015 00:00:37 -0700
- Subject: Re: [PATCH v5] Add Guile frame unwinder interface
- Authentication-results: sourceware.org; auth=none
- References: <87zj6hdq6b dot fsf at igalia dot com>
Andy Wingo <wingo@igalia.com> writes:
> Hi,
When we last left our story ...
Just a few more nits.
>
> Changes in this patch:
>
> * Remove enable-frame-unwinder!, disable-frame-unwinder!
>
> * set-frame-unwinder-enabled! takes frame unwinder object only, not a
> name
>
> * Removed priority; instead, first the unwinders for the current
> objfile are run, then the ones from the current progspace, then the
> global ones, but in an unspecified order within each locus
>
> * Renamed "scope" to "locus"
>
> * Names required to be unique only within locus
>
> * s/ephemeral frame/pending frame/
>
> * Documentation updates
>
> * make-unwind-info takes a frame-id object; added a make-frame-id
> constructor.
>
> * There's no recursion check in scm-frame-unwinder.c; instead the
> check in frame_unwind_is_unwinding is sufficient.
>
> * I kept the #:enabled init keyword to make-frame-unwinder, as it
> matches what frame filters do, as well as python filters/unwinders.
> Let me know if that was an error.
>
> * Removed dead "has-active-frame-unwinders?"
>
> * Fixed docstring on "all-frame-unwinders"
>
> * (prune-frame-unwinders!) doesn't cons if all unwinders are valid
> (i.e. their loci haven't gone away), and fix prune-frame-unwinders!
> docstring.
>
> * Renamed unregister-frame-unwinder! to remove-frame-unwinder!, as
> requested.
>
> * Fixed test coding style
>
> * Fixed some trailing .* in pattern
>
> * Test unwind before and after enabling unwinder
>
> Still to do:
>
> * Make the test architecture-independent if possible
>
> There were a couple of questions on the review from v4 of this patch
> that I address specifically in the thread for v4 and don't mention
> above.
>
> WDYT? :)
>
> Andy
Copying over from the other thread, if you want to keep priorities, ok.
Otherwise, you'll need to remove them from the documentation below.
>
> From 898b8fd80dc5b533be9219472af7645e91d37985 Mon Sep 17 00:00:00 2001
> From: Andy Wingo <wingo@igalia.com>
> Date: Thu, 5 Mar 2015 16:40:20 +0100
> Subject: [PATCH] Add Guile frame unwinder interface
>
> gdb/doc/ChangeLog:
>
> * guile.texi (Guile Frame Unwinder API): New section.
>
> gdb/ChangeLog:
>
> * guile/scm-symbol.c (gdbscm_lookup_symbol): Don't error if there
> is no selected frame and no block is selected; instead, fall back
> to the current frame.
> * guile/scm-frame-unwinder.c: New file.
> * guile/lib/gdb/frame-unwinders.scm: New file.
> * guile/guile.c (initialize_gdb_module): Call
> gdbscm_initialize_frame_unwinders.
> * guile/guile-internal.h (gdbscm_initialize_frame_unwinders): New
> declaration.
> * frame.c (get_prev_frame): Detect recursive unwinds, returning
> NULL in that case.
> * frame-unwind.h (frame_unwind_got_bytes): Make buf arg const.
> (frame_unwind_is_unwinding): New declaration.
> * frame-unwind.c (is_unwinding): New file-local variable.
> (set_is_unwinding, unset_is_unwinding): New file-local helpers.
> (frame_unwind_is_unwinding): New exported predicate.
> (frame_unwind_try_handler): Arrange for
> frame_unwind_is_unwinding to return true when unwinding the
> innermost frame.
> (frame_unwind_got_bytes): Make buf arg const.
> * data-directory/Makefile.in (GUILE_SOURCE_FILES): Add
> frame-unwinders.scm.
> (GUILE_COMPILED_FILES): Add frame-unwinders.go.
> * Makefile.in (SUBDIR_GUILE_OBS): Add scm-frame-unwinder.o.
> (SUBDIR_GUILE_SRCS): Add scm-frame-unwinder.c
> (scm-frame-unwinder.o): New target.
>
> gdb/testsuite/ChangeLog:
>
> * gdb.guile/scm-frame-unwinder.exp:
> * gdb.guile/scm-frame-unwinder.c:
> * gdb.guile/scm-frame-unwinder-gdb.scm.in:
> * gdb.guile/scm-frame-unwinder.scm: Add unwinder tests.
> ---
> gdb/ChangeLog | 29 ++
> gdb/Makefile.in | 6 +
> gdb/data-directory/Makefile.in | 2 +
> gdb/doc/ChangeLog | 4 +
> gdb/doc/guile.texi | 210 ++++++++
> gdb/frame-unwind.c | 38 +-
> gdb/frame-unwind.h | 7 +-
> gdb/frame.c | 16 +
> gdb/guile/guile-internal.h | 1 +
> gdb/guile/guile.c | 1 +
> gdb/guile/lib/gdb/frame-unwinders.scm | 235 +++++++++
> gdb/guile/scm-frame-unwinder.c | 570 +++++++++++++++++++++
> gdb/guile/scm-symbol.c | 4 +-
> gdb/testsuite/ChangeLog | 7 +
> .../gdb.guile/scm-frame-unwinder-gdb.scm.in | 31 ++
> gdb/testsuite/gdb.guile/scm-frame-unwinder.c | 35 ++
> gdb/testsuite/gdb.guile/scm-frame-unwinder.exp | 90 ++++
> gdb/testsuite/gdb.guile/scm-frame-unwinder.scm | 41 ++
> 18 files changed, 1324 insertions(+), 3 deletions(-)
> create mode 100644 gdb/guile/lib/gdb/frame-unwinders.scm
> create mode 100644 gdb/guile/scm-frame-unwinder.c
> create mode 100644 gdb/testsuite/gdb.guile/scm-frame-unwinder-gdb.scm.in
> create mode 100644 gdb/testsuite/gdb.guile/scm-frame-unwinder.c
> create mode 100644 gdb/testsuite/gdb.guile/scm-frame-unwinder.exp
> create mode 100644 gdb/testsuite/gdb.guile/scm-frame-unwinder.scm
>
> diff --git a/gdb/ChangeLog b/gdb/ChangeLog
> index 1f15ae6..9af328d 100644
> --- a/gdb/ChangeLog
> +++ b/gdb/ChangeLog
> @@ -1,5 +1,34 @@
> 2015-04-09 Andy Wingo <wingo@igalia.com>
>
> + * guile/scm-symbol.c (gdbscm_lookup_symbol): Don't error if there
> + is no selected frame and no block is selected; instead, fall back
> + to the current frame.
> + * guile/scm-frame-unwinder.c: New file.
> + * guile/lib/gdb/frame-unwinders.scm: New file.
> + * guile/guile.c (initialize_gdb_module): Call
> + gdbscm_initialize_frame_unwinders.
> + * guile/guile-internal.h (gdbscm_initialize_frame_unwinders): New
> + declaration.
> + * frame.c (get_prev_frame): Detect recursive unwinds, returning
> + NULL in that case.
> + * frame-unwind.h (frame_unwind_got_bytes): Make buf arg const.
> + (frame_unwind_is_unwinding): New declaration.
> + * frame-unwind.c (is_unwinding): New file-local variable.
> + (set_is_unwinding, unset_is_unwinding): New file-local helpers.
> + (frame_unwind_is_unwinding): New exported predicate.
> + (frame_unwind_try_handler): Arrange for
> + frame_unwind_is_unwinding to return true when unwinding the
> + innermost frame.
> + (frame_unwind_got_bytes): Make buf arg const.
> + * data-directory/Makefile.in (GUILE_SOURCE_FILES): Add
> + frame-unwinders.scm.
> + (GUILE_COMPILED_FILES): Add frame-unwinders.go.
> + * Makefile.in (SUBDIR_GUILE_OBS): Add scm-frame-unwinder.o.
> + (SUBDIR_GUILE_SRCS): Add scm-frame-unwinder.c
> + (scm-frame-unwinder.o): New target.
> +
> +2015-04-09 Andy Wingo <wingo@igalia.com>
> +
> * guile/scm-frame-filter.c:
> * guile/lib/gdb/frame-filters.scm: New files.
> * guile/guile.c (guile_extension_ops): Add the Guile frame
> diff --git a/gdb/Makefile.in b/gdb/Makefile.in
> index 4c664ae..08f432b 100644
> --- a/gdb/Makefile.in
> +++ b/gdb/Makefile.in
> @@ -322,6 +322,7 @@ SUBDIR_GUILE_OBS = \
> scm-exception.o \
> scm-frame.o \
> scm-frame-filter.o \
> + scm-frame-unwinder.o \
> scm-gsmob.o \
> scm-iterator.o \
> scm-lazy-string.o \
> @@ -349,6 +350,7 @@ SUBDIR_GUILE_SRCS = \
> guile/scm-exception.c \
> guile/scm-frame.c \
> guile/scm-frame-filter.c \
> + guile/scm-frame-unwinder.c \
> guile/scm-gsmob.c \
> guile/scm-iterator.c \
> guile/scm-lazy-string.c \
> @@ -2440,6 +2442,10 @@ scm-frame-filter.o: $(srcdir)/guile/scm-frame-filter.c
> $(COMPILE) $(srcdir)/guile/scm-frame-filter.c
> $(POSTCOMPILE)
>
> +scm-frame-unwinder.o: $(srcdir)/guile/scm-frame-unwinder.c
> + $(COMPILE) $(srcdir)/guile/scm-frame-unwinder.c
> + $(POSTCOMPILE)
> +
> scm-gsmob.o: $(srcdir)/guile/scm-gsmob.c
> $(COMPILE) $(srcdir)/guile/scm-gsmob.c
> $(POSTCOMPILE)
> diff --git a/gdb/data-directory/Makefile.in b/gdb/data-directory/Makefile.in
> index 21e44b9..b36506c 100644
> --- a/gdb/data-directory/Makefile.in
> +++ b/gdb/data-directory/Makefile.in
> @@ -90,6 +90,7 @@ GUILE_SOURCE_FILES = \
> gdb/boot.scm \
> gdb/experimental.scm \
> gdb/frame-filters.scm \
> + gdb/frame-unwinders.scm \
> gdb/init.scm \
> gdb/iterator.scm \
> gdb/printing.scm \
> @@ -102,6 +103,7 @@ GUILE_NO_UNBOUND_WARNING_COMPILED_FILES = \
> GUILE_COMPILED_FILES = \
> gdb/experimental.go \
> gdb/frame-filters.go \
> + gdb/frame-unwinders.go \
> gdb/iterator.go \
> gdb/printing.go \
> gdb/support.go \
> diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
> index bcff616..d637482 100644
> --- a/gdb/doc/ChangeLog
> +++ b/gdb/doc/ChangeLog
> @@ -1,5 +1,9 @@
> 2015-04-09 Andy Wingo <wingo@igalia.com>
>
> + * guile.texi (Guile Frame Unwinder API): New section.
> +
> +2015-04-09 Andy Wingo <wingo@igalia.com>
> +
> * guile.texi (Guile Frame Filter API)
> (Writing a Frame Filter in Guile): New sections.
>
> diff --git a/gdb/doc/guile.texi b/gdb/doc/guile.texi
> index e2826f0..6c850a4 100644
> --- a/gdb/doc/guile.texi
> +++ b/gdb/doc/guile.texi
> @@ -143,6 +143,7 @@ from the Guile interactive prompt.
> * Writing a Guile Pretty-Printer:: Writing a pretty-printer
> * Guile Frame Filter API:: Filtering frames.
> * Writing a Frame Filter in Guile:: Writing a frame filter.
> +* Guile Frame Unwinder API:: Programmatically unwinding stack frames
> * Commands In Guile:: Implementing new commands in Guile
> * Parameters In Guile:: Adding new @value{GDBN} parameters
> * Progspaces In Guile:: Program spaces
> @@ -2119,6 +2120,215 @@ also possible to do the job of an decorator with a filter. Still,
> avoiding the stream interfaces can often be a good reason to use the
> simpler decorator layer.
>
> +@node Guile Frame Unwinder API
> +@subsubsection Unwinding Frames in Guile
> +@cindex frame unwinder api, guile
> +
> +In @value{GDBN} terminology, ``unwinding'' is the process of finding
> +an older (outer) frame on the stack. Unwinders form the core of
> +backtrace computation in @value{GDBN}. @value{GDBN} comes with
> +unwinders for each target architecture that it supports, and these
> +usually suffice to unwind the stack. However, some target programs
> +can have non-standard frame layouts that cannot be unwound by the
> +standard unwinders. This is often the case when working with
> +just-in-time compilation environments, for example in JavaScript
> +implementations. In such cases, users can define custom code in Guile
> +to programmatically unwind the problematic stack frames.
> +
> +Before getting into the API, we should discuss how unwinders work in
> +@value{GDBN}.
> +
> +As an example, consider a stack in which we have already computed
> +frame 0 and we want to compute frame 1. We say that frame 0 is the
> +``inner'' frame, and frame 1 will be the ``outer'' frame.
> +
> +Unwinding starts with a model of the state of all registers in an
> +inner, already unwound frame. In our case, we start with frame 0.
> +@value{GDBN} then constructs a provisional frame object for the outer
> +frame that is being built (frame 1) and links it to the inner frame
> +(frame 0). @value{GDBN} then goes through its list of registered
> +unwinders, searching for one that knows how to compute the register
> +state in frame 1, given the state of frame 0. @value{GDBN} will then
> +ask the chosen unwinder to compute a frame identifier for the outer
> +frame. Once the unwinder has done so, the frame is marked as
> +``valid'' and can be accessed using the normal frame API.
> +
> +A frame identifier (frame ID) consists of code and data pointers
> +associated with a frame which will remain valid as long as the frame
> +is still alive. Usually a frame ID is built from the code and stack
> +pointers as they were when control entered the function associated
> +with the frame, though as described below there are other ways to
> +build a frame ID@. However as you can see, computing the frame ID
> +requires some input from the unwinder to determine the start code
> +address (PC) and the frame pointer (FP), especially on platforms that
> +don't dedicate a register to the FP.
> +
> +(Given this description, you might wonder how the frame ID for the
> +innermost frame (frame 0) is unwound, given that unwinding requires an
> +inner frame. The answer is that internally, @value{GDBN} always has a
> +``sentinel'' frame that is inner to the innermost frame, and which has
> +a pre-computed unwinder that just returns the registers as they are,
> +without unwinding.)
> +
> +The Guile frame unwinder API loosely follows this protocol as
> +described above. Guile will build a special ``pending frame object''
> +corresponding the frame being unwound (in our example, frame 1). It
to the frame
> +allows the user to read registers from that pending frame, which in
> +reality are unwound from the already-existing frame 0. If the
> +unwinder decides that it can handle the frame in question, it then
> +creates and returns an ``unwind info'' object for that frame. The
> +unwind info object contains a frame ID for the pending frame. It also
> +records the values of any registers saved in the frame, for use when
> +unwinding its outer frame (frame 2).
> +
> +Frame unwinder objects are managed in Guile much in the same way as
> +frame filters. Indeed, users will often want to implement both frame
> +unwinders and frame filters: unwinders will compute the correct
> +backtrace and register state, and filters can fill in function names,
> +line numbers, and the like. @xref{Guile Frame Filter API}, for more
> +on frame filters.
> +
> +As with frame filters, there can be multiple frame unwinders
> +registered with @value{GDBN}, and each one may be individually enabled
> +or disabled at will. The filters will be tried in priority order,
> +from highest to lowest priority, and the first one that sets the frame
> +ID will take responsibility for the frame.
> +
> +To use frame unwinders, first load the @code{(gdb frame-unwinders)} module
> +to have access to the procedures that manipulate frame unwinders:
> +
> +@example
> +(use-modules (gdb frame-unwinders))
> +@end example
> +
> +@deffn {Scheme Procedure} make-frame-unwinder name procedure @
> + @r{[}#:priority priority@r{]} @r{[}#:enabled? boolean@r{]}
> +Make a new frame unwinder.
> +
> +The unwinder will be identified by the string @var{name}.
> +@var{procedure} should be a function of one argument, taking a pending
> +frame object. If the unwinder procedure decides to handle the frame,
> +it should return an unwind info object. Otherwise if the unwinder
> +returns @code{#f}, @value{GDBN} will continue to search its list for
> +an unwinder.
> +
> +The unwinder will be initially enabled, unless the keyword argument
> +@code{#:enabled? #f} is given. Even if the unwinder is marked as
> +enabled, it will need to be registered with @value{GDBN} via
> +@code{register-frame-unwinder!} in order to take effect.
> +@end deffn
> +
> +@deffn {Scheme Procedure} all-frame-unwinders
> +Return a list of all frame unwinders.
> +@end deffn
> +
> +@deffn {Scheme Procedure} register-frame-unwinder! unwinder @
> + @r{[}#:locus locus@r{]}
> +Register the frame unwinder @var{unwinder} with @value{GDBN}.
> +
> +The unwinder will be associated with a specific ``locus'', which may
> +be an objfile, a progspace, or the ``global'' locus, indicating that
> +the unwinder should run for all progspaces. The default value of
> +@code{#f} for @var{locus} indicates that the unwinder should be
> +registered globally. Pass an objfile or a progspace as the
> +@code{#:locus} keyword argument to associate the unwinder with a
> +specific objfile or progspace, respectively.
> +@end deffn
> +
> +Registering an unwinder on an objfile or a progspace locus has the
> +advantage that the unwinder will go away when the objfile or progspace
> +is unloaded. To explicitly remove an unwinder from GDB, use
> +@code{remove-frame-unwinder!}.
> +
> +@deffn {Scheme Procedure} remove-frame-unwinder! unwinder
> +Removes the frame unwinder @var{unwinder} from @value{GDBN}.
> +@end deffn
> +
> +@deffn {Scheme Procedure} set-frame-unwinder-enabled! unwinder enabled?
> +Mark a frame unwinder as enabled, if @var{enabled?} is true, or as
> +disabled otherwise.
> +@end deffn
> +
> +Unwinders are enabled when they are created, unless @code{#:enabled?
> +#f} is passed to @code{make-frame-unwinder}.
This sentence can be deleted, just repeats what's said above.
> +
> +@deffn {Scheme Procedure} frame-unwinder-name unwinder
> +@deffnx {Scheme Procedure} frame-unwinder-enabled? unwinder
> +@deffnx {Scheme Procedure} frame-unwinder-registered? unwinder
> +@deffnx {Scheme Procedure} frame-unwinder-priority unwinder
> +@deffnx {Scheme Procedure} frame-unwinder-procedure unwinder
> +@deffnx {Scheme Procedure} frame-unwinder-locus unwinder
> +Accessors for a frame unwinder object's fields. The
> +@code{registered?} field indicates whether a unwinder has been added
> +to @value{GDBN} or not. @code{locus} is the objfile or progspace in
> +which the unwinder was registered, or @code{#f} otherwise.
> +@end deffn
> +
> +Frame unwinders operate on ``pending frames''. Pending frames are
> +valid only while they are being unwound; any access to a pending frame
> +outside the extent of their unwind operation will signal an error.
> +Currently, pending frames can only be used in two limited ways: to
> +read registers from the frame, and to construct an unwind info object
> +for a successful unwinder return.
> +
> +@deffn {Scheme Procedure} pending-frame-read-register frame register
> +Return the value of a register in the pending frame @var{frame}.
> +@var{register} should be given as a string.
> +@end deffn
> +
> +If an unwinder successfully unwinds a frame, it should return an
> +unwind info object created via the @code{make-unwind-info} procedure.
> +An unwind info object specifies the frame ID for its associated
> +pending frame, and also records values of registers that are saved
> +within the frame.
> +
> +@deffn {Scheme Procedure} make-unwind-info frame frame-id
> +Make an unwind info object for the pending frame @var{frame},
> +specifying @var{frame-id} as its frame ID. @var{frame-id} should be
> +the result of a call to @code{make-frame-id}.
> +@end deffn
> +
> +@deffn {Scheme Procedure} make-frame-id fp @r{[}#:pc pc@r{]} @r{[}#:special special@r{]}
> +Build a frame ID object from the given @var{fp}, @var{pc}, and
> +@var{special} values.
> +
> +A frame ID is a unique name for a frame that remains valid as long as
> +the frame itself is valid. Usually the frame ID is built from from
s/from from/from/
> +the frame's stack address and code address. The stack address
> +@var{fp} should normally be a pointer to the new end of the stack when
> +the function was called, as a @value{GDBN} value. Similarly the code
> +address @var{pc} should be given as the address of the entry point of
> +the function.
> +
> +The @var{fp} argument is required. While it is a good idea to specify
> +a @var{pc}, a code address is not required to build a frame ID, and so
> +@var{pc} is a keyword argument. Call @code{make-frame-id} with
> +a @code{#:pc @var{pc}} argument to specify a code address.
> +
> +Some architectures have another stack or some other frame state store;
> +currently this is only the case for ia64. For these odd platforms the
> +frame ID needs an additional address, which may be passed as the
> +@var{special} argument, via the @code{#:special} keyword.
> +@end deffn.
> +
> +After building an unwind info object for a pending frame, an unwinder
> +can call @code{unwind-info-add-saved-register!} to record saved
> +registers. The values of the saved registers logically belong to the
> +frame that is older than the pending frame being unwound, not to the
> +pending frame itself.
> +
> +@deffn {Scheme Procedure} unwind-info-add-saved-register! unwind-info register value
> +Set the saved value of a register in a pending frame.
> +
> +@var{register} names a register, and should be a string, for example
> +@samp{rip}. @var{value} is the register value, as a @value{GDBN}
> +value.
> +@end deffn
> +
> +Any register whose value is not recorded as saved via
> +@code{unwind-info-add-saved-register!} will be marked as ``not saved''
> +in the outer frame.
Copying from discussion in the other thread, how about:
"... will be marked as ``not saved'' in the pending frame being unwound."
Or one could say both:
"... will be marked as ``not saved'' in the outer frame (the pending
frame being unwound)."
Or some such.
> +
> @node Commands In Guile
> @subsubsection Commands In Guile
>
> diff --git a/gdb/frame-unwind.c b/gdb/frame-unwind.c
> index bba1ae7..4347dca 100644
> --- a/gdb/frame-unwind.c
> +++ b/gdb/frame-unwind.c
> @@ -87,6 +87,34 @@ frame_unwind_append_unwinder (struct gdbarch *gdbarch,
> (*ip)->unwinder = unwinder;
> }
>
> +/* Nonzero if we are finding the unwinder for a frame; see
> + frame_unwind_try_handler. */
> +static int is_unwinding = 0;
> +
> +/* Return nonzero if we are inside a sniffer call. */
> +
> +int
> +frame_unwind_is_unwinding (void)
> +{
> + return is_unwinding;
> +}
> +
> +/* Cleanup helpers for is_unwinding. */
> +
> +static void
> +unset_is_unwinding (void *unused)
> +{
> + is_unwinding = 0;
> +}
> +
> +static struct cleanup*
> +set_is_unwinding (void)
> +{
> + is_unwinding = 1;
> +
> + return make_cleanup (unset_is_unwinding, NULL);
> +}
> +
> /* Call SNIFFER from UNWINDER. If it succeeded set UNWINDER for
> THIS_FRAME and return 1. Otherwise the function keeps THIS_FRAME
> unchanged and returns 0. */
> @@ -98,11 +126,18 @@ frame_unwind_try_unwinder (struct frame_info *this_frame, void **this_cache,
> struct cleanup *old_cleanup;
> int res = 0;
>
> + if (is_unwinding)
> + internal_error (__FILE__, __LINE__,
> + _("Recursion detected while finding an unwinder."));
> old_cleanup = frame_prepare_for_sniffer (this_frame, unwinder);
>
> TRY
> {
> + struct cleanup *cleanup = set_is_unwinding ();
> +
> res = unwinder->sniffer (unwinder, this_frame, this_cache);
> +
> + do_cleanups (cleanup);
> }
> CATCH (ex, RETURN_MASK_ERROR)
> {
> @@ -252,7 +287,8 @@ frame_unwind_got_constant (struct frame_info *frame, int regnum,
> }
>
> struct value *
> -frame_unwind_got_bytes (struct frame_info *frame, int regnum, gdb_byte *buf)
> +frame_unwind_got_bytes (struct frame_info *frame, int regnum,
> + const gdb_byte *buf)
> {
> struct gdbarch *gdbarch = frame_unwind_arch (frame);
> struct value *reg_val;
> diff --git a/gdb/frame-unwind.h b/gdb/frame-unwind.h
> index 44add12..3e322f2 100644
> --- a/gdb/frame-unwind.h
> +++ b/gdb/frame-unwind.h
> @@ -179,6 +179,11 @@ extern void frame_unwind_append_unwinder (struct gdbarch *gdbarch,
> extern void frame_unwind_find_by_frame (struct frame_info *this_frame,
> void **this_cache);
>
> +/* Return nonzero if we are in the process of finding an unwinder for a frame.
> + See the comments in get_current_frame. */
> +
> +extern int frame_unwind_is_unwinding (void);
> +
> /* Helper functions for value-based register unwinding. These return
> a (possibly lazy) value of the appropriate type. */
>
> @@ -210,7 +215,7 @@ struct value *frame_unwind_got_constant (struct frame_info *frame, int regnum,
> inside BUF. */
>
> struct value *frame_unwind_got_bytes (struct frame_info *frame, int regnum,
> - gdb_byte *buf);
> + 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
> diff --git a/gdb/frame.c b/gdb/frame.c
> index b3cbf23..9e63f21 100644
> --- a/gdb/frame.c
> +++ b/gdb/frame.c
> @@ -2212,6 +2212,22 @@ get_prev_frame (struct frame_info *this_frame)
> return NULL;
> }
>
> + /* Unwinders implemented in Python or Scheme could eventually make an API call
> + that would cause GDB to try to unwind a frame while unwinding a frame.
> + Because already-unwound frames will be found in the frame cache, unwinding
> + will only happen at the old end of the stack, which means that any
> + recursive unwinding attempt will surely lead to unbounded recursion. Ways
> + this can happen include such common functions as `get_current_arch' or
> + `lookup_symbol', via `get_selected_frame', so it's impractical to simply
> + declare these an error. Instead, we detect this case and return NULL,
> + indicating that the known stack of frames ends here. */
> + if (frame_unwind_is_unwinding ())
> + {
> + frame_debug_got_null_frame (this_frame,
> + "get_prev_frame within unwinder sniffer");
> + return NULL;
> + }
> +
> return get_prev_frame_always (this_frame);
> }
>
> diff --git a/gdb/guile/guile-internal.h b/gdb/guile/guile-internal.h
> index d7c166c..9ca807e 100644
> --- a/gdb/guile/guile-internal.h
> +++ b/gdb/guile/guile-internal.h
> @@ -598,6 +598,7 @@ extern void gdbscm_initialize_disasm (void);
> extern void gdbscm_initialize_exceptions (void);
> extern void gdbscm_initialize_frames (void);
> extern void gdbscm_initialize_frame_filters (void);
> +extern void gdbscm_initialize_frame_unwinders (void);
> extern void gdbscm_initialize_iterators (void);
> extern void gdbscm_initialize_lazy_strings (void);
> extern void gdbscm_initialize_math (void);
> diff --git a/gdb/guile/guile.c b/gdb/guile/guile.c
> index 176e97e..d1850e7 100644
> --- a/gdb/guile/guile.c
> +++ b/gdb/guile/guile.c
> @@ -670,6 +670,7 @@ initialize_gdb_module (void *data)
> gdbscm_initialize_disasm ();
> gdbscm_initialize_frames ();
> gdbscm_initialize_frame_filters ();
> + gdbscm_initialize_frame_unwinders ();
> gdbscm_initialize_iterators ();
> gdbscm_initialize_lazy_strings ();
> gdbscm_initialize_math ();
> diff --git a/gdb/guile/lib/gdb/frame-unwinders.scm b/gdb/guile/lib/gdb/frame-unwinders.scm
> new file mode 100644
> index 0000000..d668d01
> --- /dev/null
> +++ b/gdb/guile/lib/gdb/frame-unwinders.scm
> @@ -0,0 +1,235 @@
> +;; Frame unwinder support.
> +;;
> +;; Copyright (C) 2015 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/>.
> +
> +(define-module (gdb frame-unwinders)
> + #:use-module ((gdb) #:hide (frame? symbol?))
> + #:use-module (srfi srfi-1)
> + #:use-module (srfi srfi-9)
> + #:use-module (ice-9 match)
> + #:export (pending-frame-read-register
> +
> + make-frame-id
> +
> + make-unwind-info
> + unwind-info-add-saved-register!
> +
> + make-frame-unwinder
> + frame-unwinder?
> + frame-unwinder-name
> + frame-unwinder-enabled?
> + frame-unwinder-registered?
> + frame-unwinder-procedure
> + frame-unwinder-locus
> +
> + find-frame-unwinder-by-name
> +
> + register-frame-unwinder!
> + remove-frame-unwinder!
> + set-frame-unwinder-enabled!
> +
> + all-frame-unwinders))
> +
> +(define-record-type <frame-id>
> + (%make-frame-id sp pc special)
> + frame-id?
> + (sp frame-id-sp)
> + (pc frame-id-pc)
> + (special frame-id-special))
> +
> +(define* (make-frame-id sp #:key pc special)
> + "Make a new frame identifier, or \"frame ID\".
> +
> +A frame ID is a unique name for a frame that remains valid as long as
> +the frame itself is valid.
> +
> +Usually the frame ID is built from from the frame's stack address and
> +code address. The stack address, SP, should normally be a pointer to
> +the new end of the stack when the function was called, as a GDB value.
> +
> +It is possible to create a frame ID with just an SP, but it's better to
> +specify a code address (PC) via the #:pc keyword argument. The PC
> +indicates the address of the entry point of the function.
> +
> +Some architectures have another stack or some other frame state store,
> +like ia64, and they need an additional address, which may be passed as
> +the #:special keyword argument."
> + (%make-frame-id sp pc special))
> +
> +;; Silence unbound-toplevel warnings until we can load the extension.
> +(define %make-unwind-info #f)
> +
> +(define (make-unwind-info pending-frame frame-id)
> + "Make an unwind info object for a given pending frame. FRAME-ID will
> +the frame ID of the frame."
be the ...
> + (%make-unwind-info pending-frame
> + (frame-id-sp frame-id)
> + (frame-id-pc frame-id)
> + (frame-id-special frame-id)))
> +
> +(define-record-type <frame-unwinder>
> + (%make-frame-unwinder name enabled? registered? procedure locus)
> + frame-unwinder?
> + ;; string
> + (name frame-unwinder-name)
> + ;; bool
> + (enabled? frame-unwinder-enabled? set-enabled?!)
> + ;; bool
> + (registered? frame-unwinder-registered? set-registered?!)
> + ;; pending-frame -> unwind-info | #f
> + (procedure frame-unwinder-procedure)
> + ;; objfile | progspace | #f
> + (locus frame-unwinder-locus set-locus!))
> +
> +(define* (make-frame-unwinder name procedure #:key (enabled? #t))
> + "Make and return a new frame unwinder. NAME and PROCEDURE are
> +required arguments. Specify #:enabled? to set the enabled status of the
> +unwinder.
> +
> +The unwinder must be registered with GDB via `register-frame-unwinder!'
> +before it is active."
> + (let ((registered? #f) (locus #f))
> + (%make-frame-unwinder name enabled? registered? procedure locus)))
> +
> +;; List of frame unwinders.
> +(define *frame-unwinders* '())
> +
> +(define (same-scope? a b)
> + "Return #t if A and B represent the same scope, for the purposes of
> +frame unwinder selection."
> + (cond
> + ;; If either is the global locus, they share a scope.
> + ((or (not a) (not b)) #t)
> + ;; If either is an objfile, compare their progspaces, unless the
> + ;; objfile is invalid.
> + ((objfile? a) (and (objfile-valid? a)
> + (same-scope? (objfile-progspace a) b)))
> + ((objfile? b) (and (objfile-valid? b)
> + (same-scope? a (objfile-progspace b))))
> + ;; Otherwise they are progspaces. If they eq?, it's the same scope.
> + (else (eq? a b))))
> +
> +(define (is-valid? unwinder)
> + "Return #t if the locus of UNWINDER is still valid, or otherwise #f if
> +the objfile or progspace has been removed from GDB."
> + (let ((locus (frame-unwinder-locus unwinder)))
> + (cond
> + ((progspace? locus) (progspace-valid? locus))
> + ((objfile? locus) (objfile-valid? locus))
> + (else #t))))
> +
> +(define (prune-frame-unwinders!)
> + "Prune frame unwinders whose objfile or progspace has gone away."
> + (unless (and-map is-valid? *frame-unwinders*)
> + (set! *frame-unwinders*
> + (let lp ((unwinders *frame-unwinders*))
> + (match unwinders
> + (() '())
> + ((f . unwinders)
> + (cond
> + ((is-valid? f)
> + (cons f (lp unwinders)))
> + (else
> + (set-registered?! f #f)
> + (lp unwinders)))))))))
> +
> +(define (all-frame-unwinders)
> + "Return a list of all registered frame unwinders."
> + (prune-frame-unwinders!)
> + ;; Copy the list to prevent callers from mutating our state.
> + (list-copy *frame-unwinders*))
> +
> +(define* (register-frame-unwinder! unwinder #:key locus replace?)
> + "Register a frame unwinder with GDB. Frame unwinders must be
> +registered before they will be used to unwinder backtraces.
> +
> +By default, the unwinder will be registered globally. Specify an
> +objfile or a progspace as the #:locus keyword argument to instead
> +register the unwinder as belonging to a specific objfile or progspace.
> +
> +The unwinder's name must be unique within its locus. GDB will raise an
> +exception if the locus already has a unwinder registered with the given
> +name, unless a true value is passed as the #:replace? keyword argument,
> +in which case any existing unwinder will be removed from its locus."
> + (define (check-locus!)
> + (cond
> + ((objfile? locus)
> + (unless (objfile-valid? locus)
> + (error "Objfile is not valid" locus)))
> + ((progspace? locus)
> + (unless (progspace-valid? locus)
> + (error "Progspace is not valid" locus)))
> + (locus
> + (error "Invalid locus" locus))))
> + (define (duplicate-unwinder? other)
> + (and (equal? (frame-unwinder-name other)
> + (frame-unwinder-name unwinder))
> + (eq? (frame-unwinder-locus other) locus)))
> +
> + (when (frame-unwinder-registered? unwinder)
> + (error "Frame unwinder is already registered with GDB" unwinder))
> + (check-locus!)
> + (prune-frame-unwinders!)
> + (let ((found (find duplicate-unwinder? *frame-unwinders*)))
> + (when found
> + (if replace?
> + (remove-frame-unwinder! found)
> + (error "Frame unwinder with this name already present in locus"
> + (frame-unwinder-name filter)))))
> + (set-registered?! unwinder #t)
> + (set-locus! unwinder locus)
> + (set! *frame-unwinders* (cons unwinder *frame-unwinders*)))
> +
> +(define (unregister-frame-unwinder! unwinder)
s/unregister/remove/
> + "Unregister a frame unwinder."
> + (set-registered?! unwinder #f)
> + (set-locus! unwinder #f)
> + (set! *frame-unwinders* (delq unwinder *frame-unwinders*)))
> +
> +(define* (find-frame-unwinder-by-name name #:optional locus)
> + (prune-frame-unwinders!)
> + ;; First check for names within the locus, then within the scope.
> + (or (find (lambda (unwinder)
> + (and (equal? name (frame-unwinder-name unwinder))
> + (eq? (frame-unwinder-locus unwinder) locus)))
> + *frame-unwinders*)
> + (find (lambda (unwinder)
> + (and (equal? name (frame-unwinder-name unwinder))
> + (same-scope? (frame-unwinder-locus unwinder) locus)))
> + *frame-unwinders*)
> + (error "no frame unwinder found with name" name)))
> +
> +(define (set-frame-unwinder-enabled! unwinder enabled?)
> + "Enable or disable a frame unwinder."
> + (set-enabled?! unwinder enabled?)
> + *unspecified*)
> +
> +(define (unwind-frame frame)
> + (define (try-unwind locus)
> + (or-map (lambda (unwinder)
> + (and (frame-unwinder-enabled? unwinder)
> + (eq? (frame-unwinder-locus unwinder) locus)
> + ((frame-unwinder-procedure unwinder) frame)))
> + *frame-unwinders*))
> + (prune-frame-unwinders!)
> + (or (try-unwind (current-objfile))
> + (try-unwind (current-progspace))
> + ;; Try global unwinders last.
> + (try-unwind #f)))
> +
> +(load-extension "gdb" "gdbscm_load_frame_unwinders")
> diff --git a/gdb/guile/scm-frame-unwinder.c b/gdb/guile/scm-frame-unwinder.c
> new file mode 100644
> index 0000000..363830c
> --- /dev/null
> +++ b/gdb/guile/scm-frame-unwinder.c
> @@ -0,0 +1,570 @@
> +/* Scheme frame unwinding interface.
> +
> + Copyright (C) 2015 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/>. */
> +
> +/* See README file in this directory for implementation notes, coding
> + conventions, et.al. */
> +
> +#include "defs.h"
> +#include "arch-utils.h"
> +#include "frame-unwind.h"
> +#include "gdb_obstack.h"
> +#include "guile-internal.h"
> +#include "inferior.h"
> +#include "language.h"
> +#include "observer.h"
> +#include "regcache.h"
> +#include "user-regs.h"
> +#include "value.h"
> +
> +/* Non-zero if the (gdb frame-unwinders) module has been loaded. */
> +static int gdbscm_frame_unwinders_loaded = 0;
> +
> +/* The captured unwind-frame variable. */
> +static SCM unwind_frame = SCM_BOOL_F;
> +
> +/* Key that we use when associating data with an architecture. */
> +static struct gdbarch_data *uwscm_gdbarch_data;
> +
> +/* The frame unwinder interface makes pending frame objects when trying
> + to unwind frames, and unwind info objects when unwinding is successful.
> + Here we define the names for the pending frame and unwind info Scheme
> + data types. */
> +static const char pending_frame_smob_name[] = "gdb:pending-frame";
> +static const char unwind_info_smob_name[] = "gdb:unwind-info";
> +
> +/* SMOB tag for pending frames and unwind info. */
> +static scm_t_bits pending_frame_smob_tag;
> +static scm_t_bits unwind_info_smob_tag;
> +
> +/* Data associated with a pending frame. */
> +struct uwscm_pending_frame
> +{
> + /* The frame being unwound, used for the read-register interface. */
> + struct frame_info *this_frame;
> +
> + /* The architecture of the frame, here for convenience. */
> + struct gdbarch *gdbarch;
> +};
> +
> +/* Data associated with an unwind info object. */
> +struct uwscm_unwind_info
> +{
> + /* The associated pending frame. */
> + SCM frame;
> +
> + /* The frame_id for the associated pending frame. */
> + struct frame_id frame_id;
> +
> + /* A list of (REGNUM . VALUE) pairs, indicating register values for the
> + associated pending frame. */
> + SCM registers;
> +};
> +
> +/* Type predicate for pending frames. */
> +
> +static int
> +uwscm_is_pending_frame (SCM obj)
> +{
> + return SCM_SMOB_PREDICATE (pending_frame_smob_tag, obj);
> +}
> +
> +/* Data accessor for pending frames. */
> +
> +static struct uwscm_pending_frame *
> +uwscm_pending_frame_data (SCM obj)
> +{
> + gdb_assert (uwscm_is_pending_frame (obj));
> + return (struct uwscm_pending_frame *) SCM_SMOB_DATA (obj);
> +}
> +
> +/* Type predicate for unwind info. */
> +
> +static int
> +uwscm_is_unwind_info (SCM obj)
> +{
> + return SCM_SMOB_PREDICATE (unwind_info_smob_tag, obj);
> +}
> +
> +/* Data accessor for unwind_info. */
> +
> +static struct uwscm_unwind_info *
> +uwscm_unwind_info_data (SCM obj)
> +{
> + gdb_assert (uwscm_is_unwind_info (obj));
> + return (struct uwscm_unwind_info *) SCM_SMOB_DATA (obj);
> +}
> +
> +/* Build a pending frame. */
> +
> +static SCM
> +uwscm_make_pending_frame (struct frame_info *this_frame)
> +{
> + struct uwscm_pending_frame *data;
> +
> + data = scm_gc_malloc (sizeof (*data), pending_frame_smob_name);
> +
> + data->this_frame = this_frame;
> + TRY
> + {
> + data->gdbarch = get_frame_arch (this_frame);
> + }
> + CATCH (except, RETURN_MASK_ALL)
> + {
> + GDBSCM_HANDLE_GDB_EXCEPTION (except);
> + }
> + END_CATCH
> +
> + SCM_RETURN_NEWSMOB (pending_frame_smob_tag, data);
> +}
> +
> +/* Pending frames may only be accessed from Scheme within the dynamic
> + extent of the unwind callback. */
> +
> +static int
> +uwscm_pending_frame_is_valid (SCM pending_frame)
> +{
> + return uwscm_pending_frame_data (pending_frame)->this_frame != NULL;
> +}
> +
> +/* Is this a pending frame that is accessible from Scheme? */
> +
> +static int
> +uwscm_is_valid_pending_frame (SCM obj)
> +{
> + return uwscm_is_pending_frame (obj) && uwscm_pending_frame_is_valid (obj);
> +}
> +
> +/* Is this an unwind info whose associated pending frame is valid? */
> +
> +static int
> +uwscm_is_valid_unwind_info (SCM obj)
> +{
> + return uwscm_is_unwind_info (obj)
> + && uwscm_pending_frame_is_valid (uwscm_unwind_info_data (obj)->frame);
> +}
> +
> +/* Called as the unwind callback finishes to invalidate the pending
> + frame. */
> +
> +static void
> +uwscm_invalidate_pending_frame (SCM pending_frame)
> +{
> + gdb_assert (uwscm_pending_frame_is_valid (pending_frame));
> + uwscm_pending_frame_data (pending_frame)->this_frame = NULL;
> +}
> +
> +/* Raise a Scheme exception if OBJ is not a valid pending frame. */
> +
> +static void
> +uwscm_assert_valid_pending_frame (SCM obj, const char *func_name, int pos)
> +{
> + if (!uwscm_is_valid_pending_frame (obj))
> + gdbscm_throw (gdbscm_make_type_error (func_name, pos, obj,
> + "valid <gdb:pending-frame>"));
> +}
> +
> +/* Raise a Scheme exception if OBJ is not an unwind info object whose
> + associated pending frame is valid. */
> +
> +static void
> +uwscm_assert_valid_unwind_info (SCM obj, const char *func_name, int pos)
> +{
> + if (!uwscm_is_valid_unwind_info (obj))
> + gdbscm_throw (gdbscm_make_type_error (func_name, pos, obj,
> + "valid <gdb:unwind-info>"));
> +}
> +
> +/* Helper to convert a frame ID component to a CORE_ADDR. */
> +
> +static CORE_ADDR
> +uwscm_value_to_addr (SCM value, int arg)
> +{
> + struct value *c_value;
> + CORE_ADDR ret;
> +
> + if (!vlscm_is_value (value))
> + gdbscm_throw (gdbscm_make_type_error ("make-unwind-info",
> + arg, value, "<gdb:value> object"));
> +
> + c_value = vlscm_scm_to_value (value);
> +
> + TRY
> + {
> + ret = value_as_address (c_value);
> + }
> + CATCH (except, RETURN_MASK_ALL)
> + {
> + GDBSCM_HANDLE_GDB_EXCEPTION (except);
> + }
> + END_CATCH
> +
> + return ret;
> +}
> +
> +/* (%make-unwind-info pending-frame sp pc special)
> +
> + Create an unwind info structure for this pending frame. Wrapped in Scheme to
> + take a frame ID record. */
> +
> +static SCM
> +gdbscm_make_unwind_info (SCM pending_frame, SCM sp, SCM pc, SCM special)
> +{
> + struct uwscm_unwind_info *data;
> + struct frame_id frame_id;
> +
> + uwscm_assert_valid_pending_frame (pending_frame, FUNC_NAME, SCM_ARG1);
> +
> + if (gdbscm_is_false (pc))
> + frame_id = frame_id_build_wild (uwscm_value_to_addr (sp, SCM_ARG2));
> + else if (gdbscm_is_false (special))
> + frame_id = frame_id_build (uwscm_value_to_addr (sp, SCM_ARG2),
> + uwscm_value_to_addr (pc, SCM_ARG3));
> + else
> + frame_id = frame_id_build_special (uwscm_value_to_addr (sp, SCM_ARG2),
> + uwscm_value_to_addr (pc, SCM_ARG3),
> + uwscm_value_to_addr (special, SCM_ARG4));
> +
> + data = scm_gc_malloc (sizeof (*data), unwind_info_smob_name);
> +
> + data->frame = pending_frame;
> + data->frame_id = frame_id;
> + data->registers = SCM_EOL;
> +
> + SCM_RETURN_NEWSMOB (unwind_info_smob_tag, data);
> +}
> +
> +/* Convert the string REGISTER_SCM to a register number for the given
> + architecture. */
> +
> +static int
> +uwscm_scm_to_regnum (SCM register_scm, struct gdbarch *gdbarch,
> + const char *func_name, int arg)
> +{
> + int regnum;
> + struct cleanup *cleanup;
> + char *register_str;
> +
> + gdbscm_parse_function_args (func_name, arg, NULL,
> + "s", register_scm, ®ister_str);
> + cleanup = make_cleanup (xfree, register_str);
> +
> + TRY
> + {
> + regnum = user_reg_map_name_to_regnum (gdbarch, register_str,
> + strlen (register_str));
> + }
> + CATCH (except, RETURN_MASK_ALL)
> + {
> + do_cleanups (cleanup);
> + GDBSCM_HANDLE_GDB_EXCEPTION (except);
> + }
> + END_CATCH
> +
> + do_cleanups (cleanup);
> +
> + if (regnum < 0)
> + gdbscm_out_of_range_error (func_name, arg,
> + register_scm, _("unknown register"));
> +
> + return regnum;
> +}
> +
> +/* (pending-frame-read-register <gdb:pending-frame> string)
> + -> <gdb:value>
> +
> + Sniffs a register value from a pending frame. */
> +
> +static SCM
> +gdbscm_pending_frame_read_register (SCM pending_frame, SCM register_scm)
> +{
> + struct uwscm_pending_frame *data;
> + struct value *value = NULL;
> + int regnum;
> +
> + uwscm_assert_valid_pending_frame (pending_frame, FUNC_NAME, SCM_ARG1);
> + data = uwscm_pending_frame_data (pending_frame);
> + regnum = uwscm_scm_to_regnum (register_scm, data->gdbarch, FUNC_NAME,
> + SCM_ARG2);
> +
> + TRY
> + {
> + value = get_frame_register_value (data->this_frame, regnum);
> + }
> + CATCH (except, RETURN_MASK_ALL)
> + {
> + GDBSCM_HANDLE_GDB_EXCEPTION (except);
> + }
> + END_CATCH
> +
> + if (value == NULL)
> + gdbscm_out_of_range_error (FUNC_NAME, SCM_ARG2, register_scm,
> + _("cannot read register from frame"));
> +
> + return vlscm_scm_from_value (value);
> +}
> +
> +/* (unwind-info-add-saved-register! unwind-info register value)
> +
> + Records the saved value of a particular register in UNWIND_INFO's
> + corresponding pending frame. REGISTER_SCM names the register, as a
> + string, and VALUE_SCM is a <gdb:value>. */
> +
> +static SCM
> +gdbscm_unwind_info_add_saved_register_x (SCM unwind_info, SCM register_scm,
> + SCM value_scm)
> +{
> + struct uwscm_unwind_info *data;
> + struct uwscm_pending_frame *frame_data;
> + struct value *value;
> + int regnum;
> + int value_size;
> +
> + uwscm_assert_valid_unwind_info (unwind_info, FUNC_NAME, SCM_ARG1);
> + data = uwscm_unwind_info_data (unwind_info);
> + frame_data = uwscm_pending_frame_data (data->frame);
> + regnum = uwscm_scm_to_regnum (register_scm, frame_data->gdbarch,
> + FUNC_NAME, SCM_ARG2);
> +
> + if (!vlscm_is_value (value_scm))
> + gdbscm_throw (gdbscm_make_type_error (FUNC_NAME, SCM_ARG3,
> + value_scm,
> + "<gdb:value> object"));
> +
> + value = vlscm_scm_to_value (value_scm);
> + value_size = TYPE_LENGTH (value_enclosing_type (value));
> +
> + if (value_size != register_size (frame_data->gdbarch, regnum))
> + gdbscm_invalid_object_error ("unwind-info-add-saved-register!",
> + SCM_ARG3, value_scm,
> + "wrong sized value for register");
> +
> + data->registers = scm_assv_set_x (data->registers,
> + scm_from_int (regnum),
> + value_scm);
> +
> + return SCM_UNSPECIFIED;
> +}
> +
> +/* frame_unwind.this_id method. */
> +
> +static void
> +uwscm_this_id (struct frame_info *this_frame, void **cache_ptr,
> + struct frame_id *this_id)
> +{
> + SCM unwind_info = PTR2SCM (*cache_ptr);
> + struct uwscm_unwind_info *data;
> +
> + data = uwscm_unwind_info_data (unwind_info);
> + *this_id = data->frame_id;
> +}
> +
> +/* frame_unwind.prev_register. */
> +
> +static struct value *
> +uwscm_prev_register (struct frame_info *this_frame, void **cache_ptr,
> + int regnum)
> +{
> + SCM unwind_info = PTR2SCM (*cache_ptr);
> + struct uwscm_unwind_info *data;
> + SCM value_scm;
> + struct value *c_value;
> + const gdb_byte *buf;
> +
> + data = uwscm_unwind_info_data (unwind_info);
> + value_scm = scm_assv_ref (data->registers, scm_from_int (regnum));
> + if (gdbscm_is_false (value_scm))
> + return frame_unwind_got_optimized (this_frame, regnum);
> +
> + c_value = vlscm_scm_to_value (value_scm);
> + buf = value_contents (c_value);
> +
> + return frame_unwind_got_bytes (this_frame, regnum, buf);
> +}
> +
> +/* Call unwind-frame on the pending frame and check that the return
> + value is either a valid unwind info object, for a successful unwind, or
> + #f otherwise. */
> +
> +static SCM
> +do_call_unwind_frame (void *data)
> +{
> + SCM pending_frame = PTR2SCM (data);
> + SCM result;
> +
> + result = scm_call_1 (scm_variable_ref (unwind_frame), pending_frame);
> +
> + if (!gdbscm_is_false (result))
> + uwscm_assert_valid_unwind_info (result, "unwind-frame", 0);
> +
> + return result;
> +}
> +
> +/* Sniffer implementation. */
> +
> +static int
> +uwscm_sniffer (const struct frame_unwind *self, struct frame_info *this_frame,
> + void **cache_ptr)
> +{
> + SCM pending_frame;
> + SCM result;
> +
> + /* Note that it's possible to have loaded the Guile interface, but not yet
> + loaded (gdb frame-unwinders), so checking gdb_scheme_initialized is not
> + sufficient. */
> + if (!gdbscm_frame_unwinders_loaded)
> + return 0;
> +
> + pending_frame = uwscm_make_pending_frame (this_frame);
> + /* Recurse through gdbscm_call_guile so that we can just throw
> + exceptions on error. */
> + result = gdbscm_call_guile (do_call_unwind_frame,
> + SCM2PTR (pending_frame),
> + gdbscm_memory_error_p);
> +
> + /* Drop the reference to this_frame, so that future use of
> + pending_frame from Scheme will signal an error. */
> + uwscm_invalidate_pending_frame (pending_frame);
> +
> + if (gdbscm_is_exception (result))
> + {
> + gdbscm_print_gdb_exception (SCM_BOOL_F, result);
> + return 0;
> + }
> +
> + if (gdbscm_is_false (result))
> + return 0;
> +
> + *cache_ptr = SCM2PTR (scm_gc_protect_object (result));
> +
> + return 1;
> +}
> +
> +/* Frame cache release shim. */
> +
> +static void
> +uwscm_dealloc_cache (struct frame_info *this_frame, void *cache)
> +{
> + scm_gc_unprotect_object (PTR2SCM (cache));
> +}
> +
> +struct uwscm_gdbarch_data_type
> +{
> + /* Has the unwinder shim been prepended? */
> + int unwinder_registered;
> +};
> +
> +static void *
> +uwscm_gdbarch_data_init (struct gdbarch *gdbarch)
> +{
> + return GDBARCH_OBSTACK_ZALLOC (gdbarch, struct uwscm_gdbarch_data_type);
> +}
> +
> +/* New inferior architecture callback: register the Guile sniffers
> + intermediary. */
> +
> +static void
> +uwscm_on_new_gdbarch (struct gdbarch *newarch)
> +{
> + struct uwscm_gdbarch_data_type *data =
> + gdbarch_data (newarch, uwscm_gdbarch_data);
> +
> + if (!data->unwinder_registered)
> + {
> + struct frame_unwind *unwinder
> + = GDBARCH_OBSTACK_ZALLOC (newarch, struct frame_unwind);
> +
> + unwinder->type = NORMAL_FRAME;
> + unwinder->stop_reason = default_frame_unwind_stop_reason;
> + unwinder->this_id = uwscm_this_id;
> + unwinder->prev_register = uwscm_prev_register;
> + unwinder->unwind_data = (void *) newarch;
> + unwinder->sniffer = uwscm_sniffer;
> + unwinder->dealloc_cache = uwscm_dealloc_cache;
> + frame_unwind_prepend_unwinder (newarch, unwinder);
> + data->unwinder_registered = 1;
> + }
> +}
> +
> +static const scheme_function unwind_functions[] =
> +{
> + { "%make-unwind-info", 4, 0, 0, gdbscm_make_unwind_info,
> + /* Wrapped and documented in Scheme; no need for docs here. */
> + ""},
> +
> + { "pending-frame-read-register", 2, 0, 0,
> + gdbscm_pending_frame_read_register,
> + "\
> +Return the value of a register in a pending frame.\n\
> +\n\
> + Arguments: <gdb:pending-frame> string" },
> +
> + { "unwind-info-add-saved-register!", 3, 0, 0,
> + gdbscm_unwind_info_add_saved_register_x,
> + "\
> +Record the saved value of a register for a pending frame.\n\
> +\n\
> +After reading a pending frame's registers and determining that it\n\
> +can handle the frame, an unwinder will create an unwind info object and\n\
> +call this function to record saved registers for the frame. The values\n\
> +of the saved registers logically belong to the frame that is older than\n\
> +the pending frame being unwound, not to the pending frame itself.\n\
> +\n\
> +The first argument should be a <gdb:unwind-info> object. The second\n\
> +names a register, and should be a string, for example \"rip\". The\n\
> +third argument is the value, as a GDB value. By default, any register\n\
> +whose value is not added to the unwind info's saved register set\n\
> +will be marked as \"not saved\" in the outer frame." },
> +
> + END_FUNCTIONS
> +};
> +
> +/* Called by lib/gdb/frame-unwinders.scm. */
> +
> +static void
> +gdbscm_load_frame_unwinders (void *unused)
> +{
> + if (gdbscm_frame_unwinders_loaded)
> + return;
> +
> + gdbscm_frame_unwinders_loaded = 1;
> +
> + gdbscm_define_functions (unwind_functions, 0);
> +
> + unwind_frame = scm_c_lookup ("unwind-frame");
> +}
> +
> +/* Initialize the opaque pending frame and unwind info types and
> + register gdbscm_load_frame_unwinders for calling by (gdb
> + frame-unwinders). */
> +
> +void
> +gdbscm_initialize_frame_unwinders (void)
> +{
> + pending_frame_smob_tag =
> + gdbscm_make_smob_type (pending_frame_smob_name, 0);
> + unwind_info_smob_tag =
> + gdbscm_make_smob_type (unwind_info_smob_name, 0);
> +
> + uwscm_gdbarch_data =
> + gdbarch_data_register_post_init (uwscm_gdbarch_data_init);
> + observer_attach_architecture_changed (uwscm_on_new_gdbarch);
> +
> + scm_c_register_extension ("gdb", "gdbscm_load_frame_unwinders",
> + gdbscm_load_frame_unwinders, NULL);
> +}
> diff --git a/gdb/guile/scm-symbol.c b/gdb/guile/scm-symbol.c
> index 99ef928..1ad6d0c 100644
> --- a/gdb/guile/scm-symbol.c
> +++ b/gdb/guile/scm-symbol.c
> @@ -605,7 +605,9 @@ gdbscm_lookup_symbol (SCM name_scm, SCM rest)
>
> TRY
> {
> - selected_frame = get_selected_frame (_("no frame selected"));
> + selected_frame = get_selected_frame_if_set ();
> + if (selected_frame == NULL)
> + selected_frame = get_current_frame ();
> block = get_frame_block (selected_frame, NULL);
> }
> CATCH (except, RETURN_MASK_ALL)
> diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
> index e156f57..20e6a70 100644
> --- a/gdb/testsuite/ChangeLog
> +++ b/gdb/testsuite/ChangeLog
> @@ -1,5 +1,12 @@
> 2015-04-09 Andy Wingo <wingo@igalia.com>
>
> + * gdb.guile/scm-frame-unwinder.exp: New file.
> + * gdb.guile/scm-frame-unwinder.c: New file.
> + * gdb.guile/scm-frame-unwinder-gdb.scm.in: New file.
> + * gdb.guile/scm-frame-unwinder.scm: New file.
> +
> +2015-04-09 Andy Wingo <wingo@igalia.com>
> +
> * gdb.guile/amd64-scm-frame-filter-invalidarg.S:
> * gdb.guile/scm-frame-filter-gdb.scm.in:
> * gdb.guile/scm-frame-filter-invalidarg-gdb.scm.in:
> diff --git a/gdb/testsuite/gdb.guile/scm-frame-unwinder-gdb.scm.in b/gdb/testsuite/gdb.guile/scm-frame-unwinder-gdb.scm.in
> new file mode 100644
> index 0000000..5c658d5
> --- /dev/null
> +++ b/gdb/testsuite/gdb.guile/scm-frame-unwinder-gdb.scm.in
> @@ -0,0 +1,31 @@
> +;; Copyright (C) 2015 Free Software Foundation, Inc.
> +;;
> +;; 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/>.
> +
> +;; This file is part of the GDB test-suite. It tests Guile-based frame
> +;; filters.
pasto: s/filters/unwinders/
> +
> +(use-modules (gdb)
> + (gdb frame-unwinders))
> +
> +(define* (install-unwinders! #:optional (locus (current-objfile)))
> + (define (unwind-frame frame)
> + #f)
> + (define (add-unwinder! name)
> + (register-frame-unwinder! (make-frame-unwinder name unwind-frame)
> + #:locus locus))
> + (add-unwinder! "Auto-loaded dummy")
> + (add-unwinder! "Auto-loaded dummy 2"))
> +
> +(install-unwinders!)
Can we get by with one scm file, instead of the two?
[auto-loaded and manual-loaded]
> diff --git a/gdb/testsuite/gdb.guile/scm-frame-unwinder.c b/gdb/testsuite/gdb.guile/scm-frame-unwinder.c
> new file mode 100644
> index 0000000..6546c67
> --- /dev/null
> +++ b/gdb/testsuite/gdb.guile/scm-frame-unwinder.c
> @@ -0,0 +1,35 @@
> +/* Test file for the Scheme frame unwinding interface.
> +
> + Copyright (C) 2015 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/>. */
> +
> +int
> +f2 (int a)
> +{
> + return ++a;
> +}
> +
> +int
> +f1 (int a, int b)
> +{
> + return f2 (a) + b;
> +}
> +
> +int main (int argc, char *argv[])
Nit:
int
main (int argc, char *argv[])
> +{
> + return f1 (1, 2);
> +}
> diff --git a/gdb/testsuite/gdb.guile/scm-frame-unwinder.exp b/gdb/testsuite/gdb.guile/scm-frame-unwinder.exp
> new file mode 100644
> index 0000000..6fbe48a
> --- /dev/null
> +++ b/gdb/testsuite/gdb.guile/scm-frame-unwinder.exp
> @@ -0,0 +1,90 @@
> +# Copyright (C) 2015 Free Software Foundation, Inc.
> +
> +# 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/>.
> +
> +# This file is part of the GDB testsuite. It tests Guile-based
> +# frame-filters.
[for completeness sake]
Given the use of rip here, this test needs to check for amd64 target.
It's still an outstanding question as to whether we can easily make this
target independent.
> +
> +load_lib gdb-guile.exp
> +
> +standard_testfile
> +
> +if { [prepare_for_testing ${testfile}.exp ${testfile} ${srcfile}] } {
> + return -1
> +}
> +
> +# Skip all tests if Guile scripting is not enabled.
> +if { [skip_guile_tests] } { continue }
> +
> +# Make the -gdb.scm script available to gdb, it is automagically loaded by gdb.
> +# Care is taken to put it in the same directory as the binary so that
> +# gdb will find it.
> +set remote_obj_guile_file \
> + [remote_download \
> + host ${srcdir}/${subdir}/${testfile}-gdb.scm.in \
> + [standard_output_file ${testfile}-gdb.scm]]
> +
> +gdb_reinitialize_dir $srcdir/$subdir
> +gdb_test_no_output "set auto-load safe-path ${remote_obj_guile_file}" \
> + "set auto-load safe-path"
> +gdb_load ${binfile}
> +# Verify gdb loaded the script.
> +gdb_test "info auto-load guile-scripts" "Yes.*/${testfile}-gdb.scm.*" \
> + "Test auto-load had loaded guile scripts"
> +
> +if ![runto_main] then {
> + return -1
> +}
> +
> +# Load global frame-unwinders
> +set remote_guile_file [gdb_remote_download host \
> + ${srcdir}/${subdir}/${testfile}.scm]
> +gdb_scm_load_file ${remote_guile_file}
> +
> +# Test query
> +gdb_test "guile (map frame-unwinder-name (all-frame-unwinders))" \
> + "\\(\"Synthetic\" \"Dummy\" \"Auto-loaded dummy 2\" \"Auto-loaded dummy\"\\)" \
> + "all frame unwinders"
> +gdb_test "guile (map frame-unwinder-enabled? (all-frame-unwinders))" \
> + "\\(#f #t #t #t\\)" \
> + "all frame unwinders enabled?"
> +
> +gdb_test_no_output "guile (set-frame-unwinder-enabled! (find-frame-unwinder-by-name \"Dummy\") #f)" \
> + "disable dummy"
> +gdb_test "guile (frame-unwinder-enabled? (find-frame-unwinder-by-name \"Dummy\"))"\
> + "#f" \
> + "dummy not enabled"
> +gdb_test_no_output "guile (set-frame-unwinder-enabled! (find-frame-unwinder-by-name \"Dummy\") #t)" \
> + "re-enable dummy"
> +gdb_test "guile (frame-unwinder-enabled? (find-frame-unwinder-by-name \"Dummy\"))"\
> + "#t" \
> + "dummy re-enabled"
> +
> +gdb_test "bt 10" \
> + "\#0 main .*scm-frame-unwinder.c:34" \
> + "backtrace from main"
> +
> +gdb_test_no_output "guile (set-frame-unwinder-enabled! (find-frame-unwinder-by-name \"Synthetic\") #t)" \
> + "enable synthetic unwinder"
> +
> +gdb_breakpoint "f2"
> +gdb_continue_to_breakpoint "breakpoint at f2"
> +
> +# It would be nice to the backtrace at this position with and without
> +# the unwinder, but currently enabling an unwinder doesn't invalidate
> +# the frame cache.
Ah, ok.
We can fix this as a followup.
> +
> +gdb_test "bt 10"\
> + "\#0 f2 .*scm-frame-unwinder.c:23\r\n\#1 .*\#9 0x0*cabba9e5 in \\?\\? \\(\\)\r\n\\(More stack frames follow...\\)" \
Fetch the line number with gdb_get_line_number.
> + "backtrace full of cabbages"
> diff --git a/gdb/testsuite/gdb.guile/scm-frame-unwinder.scm b/gdb/testsuite/gdb.guile/scm-frame-unwinder.scm
> new file mode 100644
> index 0000000..8f91527
> --- /dev/null
> +++ b/gdb/testsuite/gdb.guile/scm-frame-unwinder.scm
> @@ -0,0 +1,41 @@
> +;; Copyright (C) 2015 Free Software Foundation, Inc.
> +;;
> +;; 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/>.
> +
> +;; This file is part of the GDB test-suite. It tests Guile-based frame
> +;; filters.
> +
> +(use-modules (gdb)
> + (gdb frame-unwinders))
> +
> +(define (dummy-unwinder frame)
> + #f)
> +
> +(register-frame-unwinder! (make-frame-unwinder "Dummy" dummy-unwinder))
> +
> +
> +(define (synthetic-unwinder frame)
> + ;; Increment the stack pointer, set IP to 0xdeadbeef
> + (let* ((this-pc (pending-frame-read-register frame "rip"))
> + (this-sp (pending-frame-read-register frame "rsp"))
> + (prev-pc (value-cast (make-value #xcabba9e5) (value-type this-pc)))
> + (prev-sp (value-add this-sp 32))
> + (frame-id (make-frame-id this-sp #:pc this-pc))
> + (unwind-info (make-unwind-info frame frame-id)))
> + (unwind-info-add-saved-register! unwind-info "rip" prev-pc)
> + (unwind-info-add-saved-register! unwind-info "rsp" prev-sp)
> + unwind-info))
> +
> +(register-frame-unwinder!
> + (make-frame-unwinder "Synthetic" synthetic-unwinder #:enabled? #f))