On Sat, 13 Mar 2021 14:41:47 +0800 Huang Pei <huangpei@xxxxxxxxxxx> wrote: > From: Jisheng Zhang <Jisheng.Zhang@xxxxxxxxxxxxx> > Looks like this was sent before, but was missing the proper authorship (which is not Jisheng). https://lore.kernel.org/linux-arm-kernel/20191225173219.4f9db436@xhacker.debian/ -- Steve > Ftrace location could include more than a single instruction in case > of some architectures (powerpc64, for now). In this case, kprobe is > permitted on any of those instructions, and uses ftrace infrastructure > for functioning. > > However, [dis]arm_kprobe_ftrace() uses the kprobe address when setting > up ftrace filter IP. This won't work if the address points to any > instruction apart from the one that has a branch to _mcount(). To > resolve this, have [dis]arm_kprobe_ftrace() use ftrace_function() to > identify the filter IP. > > Signed-off-by: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx> > Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> > --- > kernel/kprobes.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index 41fdbb7953c6..66ee28b071c2 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -1045,9 +1045,10 @@ static int prepare_kprobe(struct kprobe *p) > static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops, > int *cnt) > { > + unsigned long ftrace_ip = ftrace_location((unsigned long)p->addr); > int ret = 0; > > - ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 0, 0); > + ret = ftrace_set_filter_ip(ops, ftrace_ip, 0, 0); > if (ret) { > pr_debug("Failed to arm kprobe-ftrace at %pS (%d)\n", > p->addr, ret); > @@ -1070,7 +1071,7 @@ static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops, > * At this point, sinec ops is not registered, we should be sefe from > * registering empty filter. > */ > - ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0); > + ftrace_set_filter_ip(ops, ftrace_ip, 1, 0); > return ret; > } > > @@ -1087,6 +1088,7 @@ static int arm_kprobe_ftrace(struct kprobe *p) > static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops, > int *cnt) > { > + unsigned long ftrace_ip = ftrace_location((unsigned long)p->addr); > int ret = 0; > > if (*cnt == 1) { > @@ -1097,7 +1099,7 @@ static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops, > > (*cnt)--; > > - ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0); > + ret = ftrace_set_filter_ip(ops, ftrace_ip, 1, 0); > WARN_ONCE(ret < 0, "Failed to disarm kprobe-ftrace at %pS (%d)\n", > p->addr, ret); > return ret;
