From f794c8279d02ccd69429d816eb03fa12c130d06d Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Mon, 5 Mar 2007 23:35:38 +0100 Subject: [PATCH] [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 --- arch/s390/kernel/kprobes.c | 21 +++++++-------------- 1 file changed, 7 insertions(+), 14 deletions(-) diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c index a466bab6677e..8af549e95730 100644 --- a/arch/s390/kernel/kprobes.c +++ b/arch/s390/kernel/kprobes.c @@ -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); -- GitLab