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From: "andrew.burgess at embecosm dot com" <sourceware-bugzilla@sourceware.org>
To: gdb-prs@sourceware.org
Subject: [Bug backtrace/27147] [GNU/Linux, sparc64] GDB is unable to print
 full stack trace (got "previous frame inner to this frame" errors)
Date: Tue, 23 Feb 2021 17:48:44 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D27147

Andrew Burgess <andrew.burgess at embecosm dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |andrew.burgess at embecosm=
 dot com

--- Comment #7 from Andrew Burgess <andrew.burgess at embecosm dot com> ---
I took a look at this bug and tracked down what I think caused the regressi=
on.

If you apply this patch to GDB:

diff --git a/gdb/sparc-tdep.c b/gdb/sparc-tdep.c
index 4f9c679b55c..4da94e8e0bb 100644
--- a/gdb/sparc-tdep.c
+++ b/gdb/sparc-tdep.c
@@ -1957,7 +1957,9 @@ sparc_supply_rwindow (struct regcache *regcache,
CORE_ADDR sp, int regnum)
        {
          if (regnum =3D=3D i || regnum =3D=3D -1)
            {
-             target_read_memory (sp + ((i - SPARC_L0_REGNUM) * 8), buf, 8);
+             if (target_read_memory (sp + ((i - SPARC_L0_REGNUM) * 8), buf=
, 8)
=3D=3D -1)
+               error (_("failed to read target memory at %s"),
+                      core_addr_to_string (sp + ((i - SPARC_L0_REGNUM) * 8=
)));

              /* Handle StackGhost.  */
              if (i =3D=3D SPARC_I7_REGNUM)

Then you should find that on commit 75c6c844d9d everything is fine, but on
commit 5b6d1e4fa4f you'll start seeing error.  The reason is that inferior_=
ptid
is set to something valid in the working commit, but is now null_ptid in the
broken commit.

As an experiment I tried hacking things so that if we get into
sparc_supply_rwindow and inferior_ptid is null_ptid then we find a "suitabl=
e"
value and set it, and this does indeed resolve the issue.

Right now I'm trying to figure out the correct way that inferior_ptid shoul=
d be
getting set at this point.

--=20
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