| Message ID | 151427444611.32561.15006958504436049655.stgit@devbox |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | Separate error injection table from kprobes | expand |
On Tue, Dec 26, 2017 at 04:47:26PM +0900, Masami Hiramatsu wrote: > 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> > --- > kernel/trace/bpf_trace.c | 1 - > kernel/trace/trace_kprobe.c | 21 +++++++-------------- > 2 files changed, 7 insertions(+), 15 deletions(-) > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index d663660f8392..cefa9b0e396c 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -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_ftrace_kprobe_override_function(regs); > return 0; > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c > index 265e3e27e8dc..a7c7035963f2 100644 > --- a/kernel/trace/trace_kprobe.c > +++ b/kernel/trace/trace_kprobe.c > @@ -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; > @@ -1204,6 +1202,7 @@ 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); > @@ -1211,12 +1210,13 @@ 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(); This is great idea. Acked-by: Alexei Starovoitov <ast@kernel.org>
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index d663660f8392..cefa9b0e396c 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -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_ftrace_kprobe_override_function(regs); return 0; diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 265e3e27e8dc..a7c7035963f2 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -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; @@ -1204,6 +1202,7 @@ 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); @@ -1211,12 +1210,13 @@ 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) @@ -1324,15 +1324,8 @@ 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; }
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> --- kernel/trace/bpf_trace.c | 1 - kernel/trace/trace_kprobe.c | 21 +++++++-------------- 2 files changed, 7 insertions(+), 15 deletions(-)