Messages in this thread Patch in this message | | | Date | Wed, 18 Oct 2017 09:22:40 -0700 | From | "tip-bot for Naveen N. Rao" <> | Subject | [tip:perf/core] Revert "kprobes: Warn if optprobe handler tries to change execution path" |
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Commit-ID: 4f3a871443669c6b4d458a60ac8d8ca5eedc3f97 Gitweb: https://git.kernel.org/tip/4f3a871443669c6b4d458a60ac8d8ca5eedc3f97 Author: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> AuthorDate: Tue, 17 Oct 2017 13:48:34 +0530 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Wed, 18 Oct 2017 15:21:35 +0200
Revert "kprobes: Warn if optprobe handler tries to change execution path"
This reverts commit:
e863d539614641 ("kprobes: Warn if optprobe handler tries to change execution path")
On PowerPC, we place a probe at kretprobe_trampoline to catch function returns and with CONFIG_OPTPROBES=y, this probe gets optimized. This works for us due to the way we handle the optprobe as described in commit:
762df10bad6954 ("powerpc/kprobes: Optimize kprobe in kretprobe_trampoline()")
With the above commit, we end up with a warning. As such, revert this change.
Reported-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20171017081834.3629-1-naveen.n.rao@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org> --- kernel/kprobes.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 2d28377..15fba7f 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -387,10 +387,7 @@ void opt_pre_handler(struct kprobe *p, struct pt_regs *regs) list_for_each_entry_rcu(kp, &p->list, list) { if (kp->pre_handler && likely(!kprobe_disabled(kp))) { set_kprobe_instance(kp); - if (kp->pre_handler(kp, regs)) { - if (WARN_ON_ONCE(1)) - pr_err("Optprobe ignores instruction pointer changing.(%pF)\n", p->addr); - } + kp->pre_handler(kp, regs); } reset_kprobe_instance(); }
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