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Date: Fri, 23 Mar 2018 18:43:06 -0700
From: Alexei Starovoitov <ast@...com>
To: Daniel Borkmann <daniel@...earbox.net>, <davem@...emloft.net>
CC: <torvalds@...ux-foundation.org>, <peterz@...radead.org>,
<rostedt@...dmis.org>, <netdev@...r.kernel.org>,
<kernel-team@...com>, <linux-api@...r.kernel.org>
Subject: Re: [PATCH v2 bpf-next 5/8] bpf: introduce BPF_RAW_TRACEPOINT
On 3/23/18 5:58 PM, Alexei Starovoitov wrote:
> On 3/23/18 4:13 PM, Daniel Borkmann wrote:
>> On 03/22/2018 04:41 PM, Alexei Starovoitov wrote:
>>> 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.
>>
>> Right.
>>
>>> 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.
>>
>> Just took a quick look, so the below one would work for generating the
>> signature and function. I did till 9 here:
>>
>> #define UNPACK(...) __VA_ARGS__
>> #define REPEAT_1(FN, DL, X, ...) FN(X)
>> #define REPEAT_2(FN, DL, X, ...) FN(X) UNPACK DL REPEAT_1(FN, DL,
>> __VA_ARGS__)
>> #define REPEAT_3(FN, DL, X, ...) FN(X) UNPACK DL REPEAT_2(FN, DL,
>> __VA_ARGS__)
>> #define REPEAT_4(FN, DL, X, ...) FN(X) UNPACK DL REPEAT_3(FN, DL,
>> __VA_ARGS__)
>> #define REPEAT_5(FN, DL, X, ...) FN(X) UNPACK DL REPEAT_4(FN, DL,
>> __VA_ARGS__)
>> #define REPEAT_6(FN, DL, X, ...) FN(X) UNPACK DL REPEAT_5(FN, DL,
>> __VA_ARGS__)
>> #define REPEAT_7(FN, DL, X, ...) FN(X) UNPACK DL REPEAT_6(FN, DL,
>> __VA_ARGS__)
>> #define REPEAT_8(FN, DL, X, ...) FN(X) UNPACK DL REPEAT_7(FN, DL,
>> __VA_ARGS__)
>> #define REPEAT_9(FN, DL, X, ...) FN(X) UNPACK DL REPEAT_8(FN, DL,
>> __VA_ARGS__)
>> #define REPEAT(X, FN, DL, ...) REPEAT_##X(FN, DL, __VA_ARGS__)
>>
>> #define SARG(X) u64 arg##X
>> #define COPY(X) args[X] = arg##X
>>
>> #define __DL_COM (,)
>> #define __DL_SEM (;)
>>
>> #define __SEQ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
>>
>> #define BPF_TRACE_DECL_x(x) \
>> void bpf_trace_run##x(struct bpf_prog *prog, \
>> REPEAT(x, SARG, __DL_COM, __SEQ))
>> #define BPF_TRACE_DEFN_x(x) \
>> void bpf_trace_run##x(struct bpf_prog *prog, \
>> REPEAT(x, SARG, __DL_COM, __SEQ)) \
>> { \
>> u64 args[x]; \
>> REPEAT(x, COPY, __DL_SEM, __SEQ); \
>> __bpf_trace_run(prog, args); \
>> } \
>> EXPORT_SYMBOL_GPL(bpf_trace_run##x)
>>
>> So doing a ...
>>
>> BPF_TRACE_DECL_x(5);
>> BPF_TRACE_DEFN_x(5);
>
> interestingly that in addition to above defining
> #define __REPEAT(X, FN, DL, ...) REPEAT_##X(FN, DL, __VA_ARGS__)
> to allow recursive expansion and doing
> __REPEAT(12, BPF_TRACE_DECL_x, __DL_SEM, __SEQ_1_12);
> almost works...
> I'm guessing it's hitting preprocessor internal limit on
> number of expressions to expand.
> It expands 1-6 nicely and 7-12 are partially expanded :)
it's not the limit I'm hitting, but self referential issue.
Exactly half gets expanded.
I don't think there is an easy workaround other
than duplicating the whole chain of REPEAT macro twice
with slightly different name.
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