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From: "sergiodj at redhat dot com" <sourceware-bugzilla@sourceware.org>
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Subject: [Bug gdb/14585] New: "Error accessing memory address" when creating
 JIT internal breakpoint
Date: Fri, 14 Sep 2012 19:41:00 -0000
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http://sourceware.org/bugzilla/show_bug.cgi?id=14585

             Bug #: 14585
           Summary: "Error accessing memory address" when creating JIT
                    internal breakpoint
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: gdb
        AssignedTo: unassigned@sourceware.org
        ReportedBy: sergiodj@redhat.com
    Classification: Unclassified


I could not find an easy way to reproduce this bug so far.  The only way I
managed to do so was to:

1) git clone git://git.qemu.org/qemu.git
2) ./configure --enable-kvm --python=python2 --target-list=x86_64-softmmu
--disable-uuid --disable-werror --enable-debug --enable-fdt # you will need to
install the dependencies
3) gdb -q -ex 'run' /tmp/install-qemu/bin/qemu-system-x86_64

And you will see:

Warning:
Cannot insert breakpoint -1.
Error accessing memory address 0x34e96c: Input/output error.

Running git-bisect on gdb.git, I found the culprit as being:

a7262466d02155f5f70422804e5971f8d5e78118 is the first bad commit
commit a7262466d02155f5f70422804e5971f8d5e78118
Author: Tom Tromey <tromey@redhat.com>
Date:   Wed Feb 1 20:21:21 2012 +0000

I spent some hours debugging this problem, and apparently it happens because
the JIT code does not recreate its internal breakpoint (placed on
__jit_debug_register_code) when the inferior is created.  Somehow the
breakpoint address does not get relocated and is invalid when
insert_breakpoint_locations tries to reinsert it.

This happens on x86_64, confirmed on Fedora 17 and ArchLinux.

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