[Bug remote/13492] New: gdbserver has false watchpoint hit on pre-set DR_STATUS

[Bug remote/13492] New: gdbserver has false watchpoint hit on pre-set DR_STATUS

[jan.kratochvil at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13492

             Bug #: 13492
           Summary: gdbserver has false watchpoint hit on pre-set
                    DR_STATUS
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: remote
        AssignedTo: unassigned@sourceware.org
        ReportedBy: jan.kratochvil@redhat.com
    Classification: Unclassified
            Target: x86_64-unknown-linux-gnu


Discussed in:
http://sourceware.org/ml/gdb-patches/2011-12/msg00336.html

stepi
Hardware access (read/write) watchpoint 2: check

Value = 0
0x00007ffff785cad0 in __nanosleep_nocancel () at
../sysdeps/unix/syscall-template.S:82
82      T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
(gdb) FAIL: gdb.base/watchpoint-hw-pre-hit.exp: stepi

The code did not touch the `check' variable in any way.

gdb/i386-nat.c has for it:
              /* Only a sanity check for leftover bits (set possibly only
                 by inferior).  */
              if (i386_dr_low.unset_status)
                i386_dr_low.unset_status (I386_DR_WATCH_MASK (i));

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[Bug remote/13492] gdbserver has false watchpoint hit on pre-set DR_STATUS

[jan.kratochvil at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13492

--- Comment #1 from Jan Kratochvil <jan.kratochvil at redhat dot com> 2011-12-12 18:30:12 UTC ---
One needs to delete from:
http://sourceware.org/gdb/wiki/TestingGDB#Native_Board_File

# Can't do hardware watchpoints, in general.
set_board_info gdb,no_hardware_watchpoints 1

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[Bug remote/13492] gdbserver has false watchpoint hit on pre-set DR_STATUS

[cvs-commit at gcc dot gnu.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=13492

--- Comment #2 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> 2011-12-13 16:11:34 UTC ---
CVSROOT:    /cvs/src
Module name:    src
Changes by:    palves@sourceware.org    2011-12-13 16:11:26

Modified files:
    gdb/gdbserver  : ChangeLog i386-low.c linux-x86-low.c 

Log message:
    2011-12-13  Pedro Alves  <pedro@codesourcery.com>

    PR remote/13492

    * i386-low.c (i386_low_stopped_data_address): Avoid fetching
    DR_CONTROL unless necessary.  Extend comments.
    * linux-x86-low.c (x86_linux_prepare_to_resume): Don't write to
    DR0-3 if not used.  If any watchpoint was set, clear DR_STATUS.

Patches:
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/gdbserver/ChangeLog.diff?cvsroot=src&r1=1.521&r2=1.522
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/gdbserver/i386-low.c.diff?cvsroot=src&r1=1.7&r2=1.8
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/gdbserver/linux-x86-low.c.diff?cvsroot=src&r1=1.31&r2=1.32

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[Bug remote/13492] gdbserver has false watchpoint hit on pre-set DR_STATUS

[jan.kratochvil at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13492

Jan Kratochvil <jan.kratochvil at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED

--- Comment #3 from Jan Kratochvil <jan.kratochvil at redhat dot com> 2011-12-13 16:41:59 UTC ---
KPASS: gdb.base/watchpoint-hw-pre-hit.exp: stepi (PRMS remote/13492)

Therefore fixed now.

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