[Bug gdb/18002] gdb/infrun.c:2114: internal-error: resume: Assertion `tp->control.step_resume_breakpoint->loc->permanent' failed.

["cvs-commit at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=18002

--- Comment #4 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Pedro Alves <palves@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=68901c4d439ebceecab927932c17ea1504747c02

commit 68901c4d439ebceecab927932c17ea1504747c02
Author: Pedro Alves <palves@redhat.com>
Date:   Thu Mar 5 23:39:45 2015 +0000

    PR gdb/18002: Fix reinsert of a permanent breakpoints

    When we find out that a breakpoint is set on top of a program
    breakpoint, we mark it as "permanent".  E.g.,:

    ...
      if (bp_loc_is_permanent (loc))
        {
          loc->inserted = 1;
          loc->permanent = 1;
        }
    ...

    Note we didn't fill in the breakpoint's shadow (shadow_len remains 0).

    In case the target claims support for evaluating breakpoint
    conditions, GDB sometimes reinserts breakpoints that are already
    inserted (to update the conditions on the target side).  Since GDB
    doesn't know whether the target supports evaluating conditions _of_
    software breakpoints (vs hardware breakpoints, etc.) until it actually
    tries it, if the target doesn't actually support z0 breakpoints, GDB
    ends up reinserting a GDB-managed software/memory breakpoint
    (mem-break.c).

    And that is the case that is buggy: breakpoints that are marked
    inserted contribute their shadows (if any) to the memory returned by
    target_read_memory, to mask out breakpoints.  Permanent breakpoints
    are always marked as inserted.  So if the permanent breakpoint doesn't
    have a shadow yet in its shadow buffer, but we set shadow_len before
    calling target_read_memory, then the still clear shadow_contents
    buffer will be used by the breakpoint masking code...  And then from
    there on, the permanent breakpoint has a broken shadow buffer, and
    thus any memory read out of that address will read bogus code, and
    many random bad things fall out from that.

    The fix is just to set shadow_len at the same time shadow_contents is
    set, not one before and another after...

    Fixes all gdb.base/bp-permanent.exp FAILs on PPC64 GNU/Linux gdbserver
    and probably any other gdbserver port that doesn't do z0 breakpoints.

    gdb/ChangeLog:
    2015-03-05  Pedro Alves  <palves@redhat.com>

        PR gdb/18002
        * mem-break.c (default_memory_insert_breakpoint): Set shadow_len
        after reading the breakpoint's shadow memory.

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