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Message-ID: <50520d4a-1c07-9cca-068c-9bc737c7785f@fb.com>
Date: Fri, 23 Mar 2018 17:58:11 -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 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 :)
I guess I have to use
BPF_TRACE_DECL_x(1);
BPF_TRACE_DECL_x(2);
BPF_TRACE_DECL_x(3);
BPF_TRACE_DECL_x(4);
...
BPF_TRACE_DECL_x(12);
which doesn't look better than open coding them.
Only for BPF_TRACE_DEFN_x it's probably worth it.
> ... will generate in kernel/trace/bpf_trace.i:
>
> void bpf_foo_trace_run5(struct bpf_prog *prog, u64 arg0 , u64 arg1 , u64 arg2 , u64 arg3 , u64 arg4);
> void bpf_foo_trace_run5(struct bpf_prog *prog, u64 arg0 , u64 arg1 , u64 arg2 , u64 arg3 , u64 arg4)
> {
> u64 args[5];
> args[0] = arg0 ;
> args[1] = arg1 ;
> args[2] = arg2 ;
> args[3] = arg3 ;
> args[4] = arg4;
> __bpf_trace_run(prog, args);
> } [...]
>
> Meaning, the EVALx() macros could be removed from there, too. Potentially, the
> REPEAT() macro could sit in its own include/linux/ header for others to reuse
> or such.
feels too specific for this use case. I'd wait second user before
moving to include/linux/kernel.h
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