Re: [PATCH v2 bpf-next 5/8] bpf: introduce BPF_RAW_TRACEPOINT

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On 3/22/18 2:43 AM, Daniel Borkmann wrote:

On 03/21/2018 07:54 PM, Alexei Starovoitov wrote:
[...]

@@ -546,6 +556,53 @@ extern void ftrace_profile_free_filter(struct perf_event *event);
 void perf_trace_buf_update(void *record, u16 type);
 void *perf_trace_buf_alloc(int size, struct pt_regs **regs, int *rctxp);

+void bpf_trace_run1(struct bpf_prog *prog, u64 arg1);
+void bpf_trace_run2(struct bpf_prog *prog, u64 arg1, u64 arg2);
+void bpf_trace_run3(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		    u64 arg3);
+void bpf_trace_run4(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		    u64 arg3, u64 arg4);
+void bpf_trace_run5(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		    u64 arg3, u64 arg4, u64 arg5);
+void bpf_trace_run6(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		    u64 arg3, u64 arg4, u64 arg5, u64 arg6);
+void bpf_trace_run7(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		    u64 arg3, u64 arg4, u64 arg5, u64 arg6, u64 arg7);
+void bpf_trace_run8(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		    u64 arg3, u64 arg4, u64 arg5, u64 arg6, u64 arg7,
+		    u64 arg8);
+void bpf_trace_run9(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		    u64 arg3, u64 arg4, u64 arg5, u64 arg6, u64 arg7,
+		    u64 arg8, u64 arg9);
+void bpf_trace_run10(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		     u64 arg3, u64 arg4, u64 arg5, u64 arg6, u64 arg7,
+		     u64 arg8, u64 arg9, u64 arg10);
+void bpf_trace_run11(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		     u64 arg3, u64 arg4, u64 arg5, u64 arg6, u64 arg7,
+		     u64 arg8, u64 arg9, u64 arg10, u64 arg11);
+void bpf_trace_run12(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		     u64 arg3, u64 arg4, u64 arg5, u64 arg6, u64 arg7,
+		     u64 arg8, u64 arg9, u64 arg10, u64 arg11, u64 arg12);
+void bpf_trace_run13(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		     u64 arg3, u64 arg4, u64 arg5, u64 arg6, u64 arg7,
+		     u64 arg8, u64 arg9, u64 arg10, u64 arg11, u64 arg12,
+		     u64 arg13);
+void bpf_trace_run14(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		     u64 arg3, u64 arg4, u64 arg5, u64 arg6, u64 arg7,
+		     u64 arg8, u64 arg9, u64 arg10, u64 arg11, u64 arg12,
+		     u64 arg13, u64 arg14);
+void bpf_trace_run15(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		     u64 arg3, u64 arg4, u64 arg5, u64 arg6, u64 arg7,
+		     u64 arg8, u64 arg9, u64 arg10, u64 arg11, u64 arg12,
+		     u64 arg13, u64 arg14, u64 arg15);
+void bpf_trace_run16(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		     u64 arg3, u64 arg4, u64 arg5, u64 arg6, u64 arg7,
+		     u64 arg8, u64 arg9, u64 arg10, u64 arg11, u64 arg12,
+		     u64 arg13, u64 arg14, u64 arg15, u64 arg16);
+void bpf_trace_run17(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		     u64 arg3, u64 arg4, u64 arg5, u64 arg6, u64 arg7,
+		     u64 arg8, u64 arg9, u64 arg10, u64 arg11, u64 arg12,
+		     u64 arg13, u64 arg14, u64 arg15, u64 arg16, u64 arg17);
 void perf_trace_run_bpf_submit(void *raw_data, int size, int rctx,
 			       struct trace_event_call *call, u64 count,
 			       struct pt_regs *regs, struct hlist_head *head,

[...]

@@ -896,3 +976,206 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info)

 	return ret;
 }
+
+static __always_inline
+void __bpf_trace_run(struct bpf_prog *prog, u64 *args)
+{
+	rcu_read_lock();
+	preempt_disable();
+	(void) BPF_PROG_RUN(prog, args);
+	preempt_enable();
+	rcu_read_unlock();
+}
+
+#define EVAL1(FN, X) FN(X)
+#define EVAL2(FN, X, Y...) FN(X) EVAL1(FN, Y)
+#define EVAL3(FN, X, Y...) FN(X) EVAL2(FN, Y)
+#define EVAL4(FN, X, Y...) FN(X) EVAL3(FN, Y)
+#define EVAL5(FN, X, Y...) FN(X) EVAL4(FN, Y)
+#define EVAL6(FN, X, Y...) FN(X) EVAL5(FN, Y)
+
+#define COPY(X) args[X - 1] = arg##X;
+
+void bpf_trace_run1(struct bpf_prog *prog, u64 arg1)
+{
+	u64 args[1];
+
+	EVAL1(COPY, 1);
+	__bpf_trace_run(prog, args);
+}
+EXPORT_SYMBOL_GPL(bpf_trace_run1);
+void bpf_trace_run2(struct bpf_prog *prog, u64 arg1, u64 arg2)
+{
+	u64 args[2];
+
+	EVAL2(COPY, 1, 2);
+	__bpf_trace_run(prog, args);
+}
+EXPORT_SYMBOL_GPL(bpf_trace_run2);
+void bpf_trace_run3(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		    u64 arg3)
+{
+	u64 args[3];
+
+	EVAL3(COPY, 1, 2, 3);
+	__bpf_trace_run(prog, args);
+}
+EXPORT_SYMBOL_GPL(bpf_trace_run3);
+void bpf_trace_run4(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		    u64 arg3, u64 arg4)
+{
+	u64 args[4];
+
+	EVAL4(COPY, 1, 2, 3, 4);
+	__bpf_trace_run(prog, args);
+}
+EXPORT_SYMBOL_GPL(bpf_trace_run4);
+void bpf_trace_run5(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		    u64 arg3, u64 arg4, u64 arg5)
+{
+	u64 args[5];
+
+	EVAL5(COPY, 1, 2, 3, 4, 5);
+	__bpf_trace_run(prog, args);
+}
+EXPORT_SYMBOL_GPL(bpf_trace_run5);
+void bpf_trace_run6(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		    u64 arg3, u64 arg4, u64 arg5, u64 arg6)
+{
+	u64 args[6];
+
+	EVAL6(COPY, 1, 2, 3, 4, 5, 6);
+	__bpf_trace_run(prog, args);
+}
+EXPORT_SYMBOL_GPL(bpf_trace_run6);
+void bpf_trace_run7(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		    u64 arg3, u64 arg4, u64 arg5, u64 arg6, u64 arg7)
+{
+	u64 args[7];
+
+	EVAL6(COPY, 1, 2, 3, 4, 5, 6);
+	EVAL1(COPY, 7);
+	__bpf_trace_run(prog, args);
+}
+EXPORT_SYMBOL_GPL(bpf_trace_run7);
+void bpf_trace_run8(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		    u64 arg3, u64 arg4, u64 arg5, u64 arg6, u64 arg7,
+		    u64 arg8)
+{
+	u64 args[8];
+
+	EVAL6(COPY, 1, 2, 3, 4, 5, 6);
+	EVAL2(COPY, 7, 8);
+	__bpf_trace_run(prog, args);
+}
+EXPORT_SYMBOL_GPL(bpf_trace_run8);
+void bpf_trace_run9(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		    u64 arg3, u64 arg4, u64 arg5, u64 arg6, u64 arg7,
+		    u64 arg8, u64 arg9)
+{
+	u64 args[9];
+
+	EVAL6(COPY, 1, 2, 3, 4, 5, 6);
+	EVAL3(COPY, 7, 8, 9);
+	__bpf_trace_run(prog, args);
+}
+EXPORT_SYMBOL_GPL(bpf_trace_run9);
+void bpf_trace_run10(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		     u64 arg3, u64 arg4, u64 arg5, u64 arg6, u64 arg7,
+		     u64 arg8, u64 arg9, u64 arg10)
+{
+	u64 args[10];
+
+	EVAL6(COPY, 1, 2, 3, 4, 5, 6);
+	EVAL4(COPY, 7, 8, 9, 10);
+	__bpf_trace_run(prog, args);
+}
+EXPORT_SYMBOL_GPL(bpf_trace_run10);
+void bpf_trace_run11(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		     u64 arg3, u64 arg4, u64 arg5, u64 arg6, u64 arg7,
+		     u64 arg8, u64 arg9, u64 arg10, u64 arg11)
+{
+	u64 args[11];
+
+	EVAL6(COPY, 1, 2, 3, 4, 5, 6);
+	EVAL5(COPY, 7, 8, 9, 10, 11);
+	__bpf_trace_run(prog, args);
+}
+EXPORT_SYMBOL_GPL(bpf_trace_run11);
+void bpf_trace_run12(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		     u64 arg3, u64 arg4, u64 arg5, u64 arg6, u64 arg7,
+		     u64 arg8, u64 arg9, u64 arg10, u64 arg11, u64 arg12)
+{
+	u64 args[12];
+
+	EVAL6(COPY, 1, 2, 3, 4, 5, 6);
+	EVAL6(COPY, 7, 8, 9, 10, 11, 12);
+	__bpf_trace_run(prog, args);
+}
+EXPORT_SYMBOL_GPL(bpf_trace_run12);
+void bpf_trace_run17(struct bpf_prog *prog, u64 arg1, u64 arg2,
+		     u64 arg3, u64 arg4, u64 arg5, u64 arg6, u64 arg7,
+		     u64 arg8, u64 arg9, u64 arg10, u64 arg11, u64 arg12,
+		     u64 arg13, u64 arg14, u64 arg15, u64 arg16, u64 arg17)
+{
+	u64 args[17];
+
+	EVAL6(COPY, 1, 2, 3, 4, 5, 6);
+	EVAL6(COPY, 7, 8, 9, 10, 11, 12);
+	EVAL5(COPY, 13, 14, 15, 16, 17);
+	__bpf_trace_run(prog, args);
+}
+EXPORT_SYMBOL_GPL(bpf_trace_run17);


Would be nice if we could generate all these above via macro, e.g. when we define
a hard upper limit for max number of tracepoint args anyway, so this gets automatically
adjusted as well. Maybe some of the logic from BPF_CALL_*() macros could be borrowed
for this purpose.


I've thought about it, but couldn't figure out how to do it.
Suggestions are welcome.
The preprocessor cannot expand a constant N into N statements.
There gotta be something like:
...
#define EVAL5(FN, X, Y...) FN(X) EVAL4(FN, Y)
#define EVAL6(FN, X, Y...) FN(X) EVAL5(FN, Y)
for whatever maximum we will pick.
I picked 6 as a good compromise and used it twice in bpf_trace_run1x()
Similar thing possible for u64 arg1, u64 arg2, ...
but it will be harder to read.
Looking forward what you can come up with.

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