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powerpc/xmon: Fix data-breakpoint

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commit c21a493a2b44650707d06741601894329486f2ad upstream.

Currently xmon data-breakpoint feature is broken.

Whenever there is a watchpoint match occurs, hw_breakpoint_handler will
be called by do_break via notifier chains mechanism. If watchpoint is
registered by xmon, hw_breakpoint_handler won't find any associated
perf_event and returns immediately with NOTIFY_STOP. Similarly, do_break
also returns without notifying to xmon.

Solve this by returning NOTIFY_DONE when hw_breakpoint_handler does not
find any perf_event associated with matched watchpoint, rather than
NOTIFY_STOP, which tells the core code to continue calling the other
breakpoint handlers including the xmon one.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ravi Bangoria 2016-11-22 14:55:59 +05:30 • committed by Greg Kroah-Hartman
parent afee78f03e
commit 15959b728d
1 changed files with 3 additions and 1 deletions
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4
arch/powerpc/kernel/hw_breakpoint.c
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@ -227,8 +227,10 @@ int __kprobes hw_breakpoint_handler(struct die_args *args)
rcu_read_lock(); rcu_read_lock();
bp = __this_cpu_read(bp_per_reg); bp = __this_cpu_read(bp_per_reg);
if (!bp) if (!bp) {
rc = NOTIFY_DONE;
goto out; goto out;
}
info = counter_arch_bp(bp); info = counter_arch_bp(bp);
/* /*