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kprobes: Warn if optprobe handler tries to change execution path

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Warn if optprobe handler tries to change execution path.
As described in Documentation/kprobes.txt, with optprobe
user handler can not change instruction pointer. In that
case user must avoid optimizing the kprobes by setting
post_handler or break_handler.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/150581521955.32348.3615624715034787365.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Masami Hiramatsu 2017-09-19 19:00:19 +09:00 committed by Ingo Molnar
parent cd52edad55
commit e863d53961
1 changed files with 4 additions and 1 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

5
kernel/kprobes.c
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@ -387,7 +387,10 @@ void opt_pre_handler(struct kprobe *p, struct pt_regs *regs)
list_for_each_entry_rcu(kp, &p->list, list) { list_for_each_entry_rcu(kp, &p->list, list) {
if (kp->pre_handler && likely(!kprobe_disabled(kp))) { if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
set_kprobe_instance(kp); set_kprobe_instance(kp);
kp->pre_handler(kp, regs); if (kp->pre_handler(kp, regs)) {
if (WARN_ON_ONCE(1))
pr_err("Optprobe ignores instruction pointer changing.(%pF)\n", p->addr);
}
} }
reset_kprobe_instance(); reset_kprobe_instance();
} }