This is the mail archive of the
gdb-patches@sources.redhat.com
mailing list for the GDB project.
Re: ppc_linux_init_extra_frame_info
On Feb 21, 1:14am, Andreas Schwab wrote:
ppc_linux_init_extra_frame_info is clobbering the frame type which
causes dummy_frame_pop to bail out. The frame type is now set before
INIT_FRAME_INFO is called.
Not always, it would appear. In create_new_frame(), the type is
set before INIT_EXTRA_FRAME_INFO() is called. However, in
legacy_get_prev_frame(), the setting of the type occurs both
before and possibly after the call to INIT_EXTRA_FRAME_INFO().
In fact, the "after" part has me concerned. I suspect that it could
cause a signal handler's frame to be marked as a sigtramp frame.
Andrew even comments on this:
/* FIXME: cagney/2002-11-10: This should be moved to before the
INIT code above so that the INIT code knows what the frame's
type is (in fact, for a [generic] dummy-frame, the type can
be set and then the entire initialization can be skipped.
Unforunatly, its the INIT code that sets the PC (Hmm, catch
22). */
Hmm,
ac131313 at lulu$ frep deprecated_set_frame_type
frame.c:1388:deprecated_set_frame_type (struct frame_info *frame, enum
frame_type type)
frame.h:251:extern void deprecated_set_frame_type (struct frame_info *,
i386-interix-tdep.c:166: deprecated_set_frame_type (frame,
SIGTRAMP_FRAME);
i386-interix-tdep.c:174: deprecated_set_frame_type (frame,
SIGTRAMP_FRAME);
ppc-linux-tdep.c:376: deprecated_set_frame_type (fi, SIGTRAMP_FRAME);
ppc-linux-tdep.c:380: deprecated_set_frame_type (fi, NORMAL_FRAME);
rs6000-tdep.c:181: deprecated_set_frame_type (fi, SIGTRAMP_FRAME);
(Joel, I'm going to ignore interix :-/)
So it's solely PPC GNU/Linux that is the cause of all the problems. An
addition to the comment;
/* FIXME: cagney/2002-11-18: Should be setting the frame's type
here, before anything else, and not last. Various INIT functions
are full of work-arounds for the frames type not being set
correctly from the word go. Ulgh! */
prev->type = NORMAL_FRAME;
is that, for legacy targets, you don't know at this point what the PC is.
Why not also modify the nasty ppc-linux hack to read:
if (get_frame_type () == NORMAL)
if (pc in sigtramp)
deprecated set frame type ()
Andrew
- behavior is ever fixed.)
-
- PC_IN_SIGTRAMP is called from blockframe.c as well in order to set
- the frame's type (if a SIGTRAMP_FRAME). Because of our strange
- definition of in_sigtramp below, we can't rely on the frame's type
- getting set correctly from within blockframe.c. This is why we
- take pains to set it in init_extra_frame_info().
-
- NOTE: cagney/2002-11-10: I suspect the real problem here is that
- the get_prev_frame() only initializes the frame's type after the
- call to INIT_FRAME_INFO. get_prev_frame() should be fixed, this
- code shouldn't be working its way around a bug :-(. */
+ behavior is ever fixed.) */
I'd prefer to have these comments left in place.
I don't agree with Andrew's comment BTW. My memory on this is rather
hazy, but I think that the problem is that we really want different
functions for PC_IN_SIGTRAMP as called from infrun.c vs frame.c.
If we could have the frame.c PC_IN_SIGRAMP calls call
ppc_linux_at_sigtramp_return_path() and the infrun.c calls call
ppc_linux_in_sigtramp(), things would work right. This suggests
that we really need two different methods.
(Take my current remarks with a grain of salt. It's been a while
since I've worked on this code...)
If you'd like to add you own notes to this comment block (or anywhere
else), I have no problem with that.
int
ppc_linux_in_sigtramp (CORE_ADDR pc, char *func_name)
@@ -374,10 +363,6 @@ ppc_linux_init_extra_frame_info (int fro
at trampoline code */
if (ppc_linux_at_sigtramp_return_path (fi->pc))
deprecated_set_frame_type (fi, SIGTRAMP_FRAME);
- else
- /* FIXME: cagney/2002-11-10: Is this double bogus? What
- happens if the frame has previously been marked as a dummy? */
- deprecated_set_frame_type (fi, NORMAL_FRAME);
}
}
This part is fine. (I.e, I think this part should be committed.)
Thanks,
Kevin