gdb and binutils branch master updated. c4d9ceb6473237e614c66be97351109b9f260505

[qiyao at sourceware dot org]

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https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=c4d9ceb6473237e614c66be97351109b9f260505

commit c4d9ceb6473237e614c66be97351109b9f260505
Author: Yao Qi <yao@codesourcery.com>
Date:   Fri Sep 12 13:35:11 2014 +0800

    Honour SIGILL and SIGSEGV in cancel breakpoint and event lwp selection
    
    I see the following fail on arm-none-linux-gnueabi testing,
    
    (gdb) continue^M
    Continuing.^M
    ^M
    Program received signal SIGILL, Illegal instruction.^M
    [Switching to Thread 1003]^M
    handler (signo=10) at
    /scratch/yqi/arm-none-linux-gnueabi/src/gdb-trunk/gdb/testsuite/gdb.threads/sigstep-threads.c:33^M
    33        tgkill (getpid (), gettid (), SIGUSR1);       /* step-2 */^M
    (gdb) FAIL: gdb.threads/sigstep-threads.exp: continue
    
    the cause is that GDBserver doesn't cancel the breakpoint if the stop
    signal is SIGILL.  The kernel used here is a little old, 2.6.x, and
    doesn't translate SIGILL to SIGTRAP when program hits breakpoint
    instruction (which is an illegal instruction actually).  GDB and
    GDBserver can translate SIGILL to SIGTRAP under certain circumstance,
    so it is not a problem here.  See gdbserver/linux-low.c:linux_wait_1
    
      /* If this event was not handled before, and is not a SIGTRAP, we
         report it.  SIGILL and SIGSEGV are also treated as traps in case
         a breakpoint is inserted at the current PC.  If this target does
         not support internal breakpoints at all, we also report the
         SIGTRAP without further processing; it's of no concern to us.  */
      maybe_internal_trap
        = (supports_breakpoints ()
           && (WSTOPSIG (w) == SIGTRAP
    	   || ((WSTOPSIG (w) == SIGILL
    		|| WSTOPSIG (w) == SIGSEGV)
    	       && (*the_low_target.breakpoint_at) (event_child->stop_pc))));
    
    However, SIGILL and SIGSEGV is not considered when cancelling
    breakpoint, which causes the fail above.  That is, when GDB is doing
    software single step on address ADDR, both thread A and thread B hits the
    software single step breakpoint, and get SIGILL.  GDB selects the event
    from thread A, removes the software single step breakpoint, and resume
    the program.  The event (SIGILL) from thread B is reported to GDB, but
    GDB doesn't regard this SIGILL as SIGTRAP, because the breakpoint on
    address ADDR was removed, so GDB reports "Program received signal
    SIGILL".
    
    The patch is to allow calling cancel_breakpoint if the signal is
    SIGILL and SIGSEGV.  This patch fixes the fail above.  Likewise, event
    lwp selection should honour SIGILL and SIGSEGV too.
    
    gdb/gdbserver:
    
    2014-09-23  Yao Qi  <yao@codesourcery.com>
    
    	* linux-low.c (lp_status_maybe_breakpoint): New function.
    	(linux_low_filter_event): Call lp_status_maybe_breakpoint.
    	(count_events_callback): Likewise.
    	(select_event_lwp_callback): Likewise.
    	(cancel_breakpoints_callback): Likewise.

-----------------------------------------------------------------------

Summary of changes:
 gdb/gdbserver/ChangeLog   |    8 ++++++++
 gdb/gdbserver/linux-low.c |   28 ++++++++++++++++++----------
 2 files changed, 26 insertions(+), 10 deletions(-)


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