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Commit 66665ad2 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Alexei Starovoitov
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tracing/kprobe: bpf: Compare instruction pointer with original one 



Compare instruction pointer with original one on the
stack instead using per-cpu bpf_kprobe_override flag.

This patch also consolidates reset_current_kprobe() and
preempt_enable_no_resched() blocks. Those can be done
in one place.

Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: default avatarJosef Bacik <jbacik@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent b4da3340

kernel/trace/bpf_trace.c

+0 −1
Original line number Diff line number Diff line
@@ -83,7 +83,6 @@ EXPORT_SYMBOL_GPL(trace_call_bpf); 
#ifdef CONFIG_BPF_KPROBE_OVERRIDE

BPF_CALL_2(bpf_override_return, struct pt_regs *, regs, unsigned long, rc)

{

	__this_cpu_write(bpf_kprobe_override, 1);

	regs_set_return_value(regs, rc);

	arch_kprobe_override_function(regs);

	return 0;

kernel/trace/trace_kprobe.c

+7 −14
Original line number Diff line number Diff line
@@ -42,8 +42,6 @@ struct trace_kprobe { 
	(offsetof(struct trace_kprobe, tp.args) +	\

	(sizeof(struct probe_arg) * (n)))



DEFINE_PER_CPU(int, bpf_kprobe_override);



static nokprobe_inline bool trace_kprobe_is_return(struct trace_kprobe *tk)

{

	return tk->rp.handler != NULL;
@@ -1205,6 +1203,7 @@ kprobe_perf_func(struct trace_kprobe *tk, struct pt_regs *regs) 
	int rctx;



	if (bpf_prog_array_valid(call)) {

		unsigned long orig_ip = instruction_pointer(regs);

		int ret;



		ret = trace_call_bpf(call, regs);
@@ -1212,12 +1211,13 @@ kprobe_perf_func(struct trace_kprobe *tk, struct pt_regs *regs) 
		/*

		 * We need to check and see if we modified the pc of the

		 * pt_regs, and if so clear the kprobe and return 1 so that we

		 * don't do the instruction skipping.  Also reset our state so

		 * we are clean the next pass through.

		 * don't do the single stepping.

		 * The ftrace kprobe handler leaves it up to us to re-enable

		 * preemption here before returning if we've modified the ip.

		 */

		if (__this_cpu_read(bpf_kprobe_override)) {

			__this_cpu_write(bpf_kprobe_override, 0);

		if (orig_ip != instruction_pointer(regs)) {

			reset_current_kprobe();

			preempt_enable_no_resched();

			return 1;

		}

		if (!ret)
@@ -1325,15 +1325,8 @@ static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs) 
	if (tk->tp.flags & TP_FLAG_TRACE)

		kprobe_trace_func(tk, regs);

#ifdef CONFIG_PERF_EVENTS

	if (tk->tp.flags & TP_FLAG_PROFILE) {

	if (tk->tp.flags & TP_FLAG_PROFILE)

		ret = kprobe_perf_func(tk, regs);

		/*

		 * The ftrace kprobe handler leaves it up to us to re-enable

		 * preemption here before returning if we've modified the ip.

		 */

		if (ret)

			preempt_enable_no_resched();

	}

#endif

	return ret;

}