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[S390] kprobes breaks BUG_ON 

The illegal operation handler calls the die notifier with DIE_BPT to
let kprobes pick up its breakpoint. If kprobes does not find its
breakpoint it returns NOTIFY_STOP instead of NOTIFY_DONE.
Since we use stop_machine_run on s390 to arm/disarm the kprobes
breakpoints the race that kprobe_handler tries to solve by checking
for the kprobes breakpoints does not exist. Removing the check makes
BUG_ON working again.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky 2007-03-05 23:35:38 +01:00
parent c3442e2965
commit f794c8279d
1 changed files with 7 additions and 14 deletions
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21
arch/s390/kernel/kprobes.c
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@ -337,21 +337,14 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
}
p = get_kprobe(addr);
if (!p) {
if (*addr != BREAKPOINT_INSTRUCTION) {
/*
* The breakpoint instruction was removed right
* after we hit it. Another cpu has removed
* either a probepoint or a debugger breakpoint
* at this address. In either case, no further
* handling of this interrupt is appropriate.
*
*/
ret = 1;
}
/* Not one of ours: let kernel handle it */
if (!p)
/*
* No kprobe at this address. The fault has not been
* caused by a kprobe breakpoint. The race of breakpoint
* vs. kprobe remove does not exist because on s390 we
* use stop_machine_run to arm/disarm the breakpoints.
*/
goto no_kprobe;
}
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
set_current_kprobe(p, regs, kcb);