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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: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Masami Hiramatsu 2018-01-13 02:54:33 +09:00 committed by Alexei Starovoitov
parent b4da3340ea
commit 66665ad2f1
2 changed files with 7 additions and 15 deletions
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1
kernel/trace/bpf_trace.c
View File

@ -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;

21
kernel/trace/trace_kprobe.c
View File

@ -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;
}