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[PATCH, REPORT] bpf_trace: build error without PERF_EVENTS

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  [PATCH, REPORT] bpf_trace: build error without PERF_EVENTS Arnd Bergmann <arnd@arndb.de> - 2015-11-10 14:10 +0100
    Re: [PATCH, REPORT] bpf_trace: build error without PERF_EVENTS Daniel Borkmann <daniel@iogearbox.net> - 2015-11-10 14:40 +0100
      Re: [PATCH, REPORT] bpf_trace: build error without PERF_EVENTS Steven Rostedt <rostedt@goodmis.org> - 2015-11-10 15:30 +0100
        Re: [PATCH, REPORT] bpf_trace: build error without PERF_EVENTS Alexei Starovoitov <alexei.starovoitov@gmail.com> - 2015-11-10 18:20 +0100
          Re: [PATCH, REPORT] bpf_trace: build error without PERF_EVENTS Daniel Borkmann <daniel@iogearbox.net> - 2015-11-10 18:30 +0100

#1266480 — [PATCH, REPORT] bpf_trace: build error without PERF_EVENTS

In my ARM randconfig tests, I'm getting a build error for
newly added code in bpf_perf_event_read and bpf_perf_event_output
whenever CONFIG_PERF_EVENTS is disabled:

kernel/trace/bpf_trace.c: In function 'bpf_perf_event_read':
kernel/trace/bpf_trace.c:203:11: error: 'struct perf_event' has no member named 'oncpu'
if (event->oncpu != smp_processor_id() ||
         ^
kernel/trace/bpf_trace.c:204:11: error: 'struct perf_event' has no member named 'pmu'
      event->pmu->count)

This can happen when UPROBE_EVENT is enabled but KPROBE_EVENT
is disabled. I'm not sure if that is a configuration we care
about, otherwise we could prevent this case from occuring by
adding Kconfig dependencies.

Simply hiding the broken code inside #ifdef CONFIG_PERF_EVENTS
as this patch does seems to reliably fix the error as well,
I have built thousands of randconfig kernels since I started
seeing this and added the workaround.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 62544ce8e01c ("bpf: fix bpf_perf_event_read() helper")
Fixes: a43eec304259 ("bpf: introduce bpf_perf_event_output() helper")
---
I suspect my patch is not the right answer, but could someone please
fix this?

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 4228fd3682c3..82e0bc9d002a 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -186,6 +186,7 @@ const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
 	return &bpf_trace_printk_proto;
 }
 
+#if IS_ENABLED(CONFIG_PERF_EVENTS)
 static u64 bpf_perf_event_read(u64 r1, u64 index, u64 r3, u64 r4, u64 r5)
 {
 	struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
@@ -263,6 +264,7 @@ static const struct bpf_func_proto bpf_perf_event_output_proto = {
 	.arg4_type	= ARG_PTR_TO_STACK,
 	.arg5_type	= ARG_CONST_STACK_SIZE,
 };
+#endif
 
 static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func_id)
 {
@@ -289,10 +291,12 @@ static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func
 		return bpf_get_trace_printk_proto();
 	case BPF_FUNC_get_smp_processor_id:
 		return &bpf_get_smp_processor_id_proto;
+#if IS_ENABLED(CONFIG_PERF_EVENTS)
 	case BPF_FUNC_perf_event_read:
 		return &bpf_perf_event_read_proto;
 	case BPF_FUNC_perf_event_output:
 		return &bpf_perf_event_output_proto;
+#endif
 	default:
 		return NULL;
 	}

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#1266501

On 11/10/2015 01:55 PM, Arnd Bergmann wrote:
> In my ARM randconfig tests, I'm getting a build error for
> newly added code in bpf_perf_event_read and bpf_perf_event_output
> whenever CONFIG_PERF_EVENTS is disabled:
>
> kernel/trace/bpf_trace.c: In function 'bpf_perf_event_read':
> kernel/trace/bpf_trace.c:203:11: error: 'struct perf_event' has no member named 'oncpu'
> if (event->oncpu != smp_processor_id() ||
>           ^
> kernel/trace/bpf_trace.c:204:11: error: 'struct perf_event' has no member named 'pmu'
>        event->pmu->count)
>
> This can happen when UPROBE_EVENT is enabled but KPROBE_EVENT
> is disabled. I'm not sure if that is a configuration we care
> about, otherwise we could prevent this case from occuring by
> adding Kconfig dependencies.

I think that seems better than spreading #if IS_ENABLEDs into the code.
Probably enough to add a 'depends on PERF_EVENTS' to config BPF_EVENTS,
so it's also explicitly documented.

> Simply hiding the broken code inside #ifdef CONFIG_PERF_EVENTS
> as this patch does seems to reliably fix the error as well,
> I have built thousands of randconfig kernels since I started
> seeing this and added the workaround.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Fixes: 62544ce8e01c ("bpf: fix bpf_perf_event_read() helper")
> Fixes: a43eec304259 ("bpf: introduce bpf_perf_event_output() helper")

Thanks,
Daniel
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#1266535

On Tue, 10 Nov 2015 14:31:38 +0100
Daniel Borkmann <daniel@iogearbox.net> wrote:

> On 11/10/2015 01:55 PM, Arnd Bergmann wrote:
> > In my ARM randconfig tests, I'm getting a build error for
> > newly added code in bpf_perf_event_read and bpf_perf_event_output
> > whenever CONFIG_PERF_EVENTS is disabled:
> >
> > kernel/trace/bpf_trace.c: In function 'bpf_perf_event_read':
> > kernel/trace/bpf_trace.c:203:11: error: 'struct perf_event' has no member named 'oncpu'
> > if (event->oncpu != smp_processor_id() ||
> >           ^
> > kernel/trace/bpf_trace.c:204:11: error: 'struct perf_event' has no member named 'pmu'
> >        event->pmu->count)
> >
> > This can happen when UPROBE_EVENT is enabled but KPROBE_EVENT
> > is disabled. I'm not sure if that is a configuration we care
> > about, otherwise we could prevent this case from occuring by
> > adding Kconfig dependencies.  
> 
> I think that seems better than spreading #if IS_ENABLEDs into the code.
> Probably enough to add a 'depends on PERF_EVENTS' to config BPF_EVENTS,
> so it's also explicitly documented.
> 

So just do the following then?

-- Steve

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 8d6363f42169..f5aecff2d243 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -434,7 +434,7 @@ config UPROBE_EVENT
 
 config BPF_EVENTS
 	depends on BPF_SYSCALL
-	depends on KPROBE_EVENT || UPROBE_EVENT
+	depends on KPROBE_EVENT && UPROBE_EVENT
 	bool
 	default y
 	help
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#1266658

On Tue, Nov 10, 2015 at 09:25:01AM -0500, Steven Rostedt wrote:
> On Tue, 10 Nov 2015 14:31:38 +0100
> Daniel Borkmann <daniel@iogearbox.net> wrote:
> 
> > On 11/10/2015 01:55 PM, Arnd Bergmann wrote:
> > > In my ARM randconfig tests, I'm getting a build error for
> > > newly added code in bpf_perf_event_read and bpf_perf_event_output
> > > whenever CONFIG_PERF_EVENTS is disabled:
> > >
> > > kernel/trace/bpf_trace.c: In function 'bpf_perf_event_read':
> > > kernel/trace/bpf_trace.c:203:11: error: 'struct perf_event' has no member named 'oncpu'
> > > if (event->oncpu != smp_processor_id() ||
> > >           ^
> > > kernel/trace/bpf_trace.c:204:11: error: 'struct perf_event' has no member named 'pmu'
> > >        event->pmu->count)
> > >
> > > This can happen when UPROBE_EVENT is enabled but KPROBE_EVENT
> > > is disabled. I'm not sure if that is a configuration we care
> > > about, otherwise we could prevent this case from occuring by
> > > adding Kconfig dependencies.  
> > 
> > I think that seems better than spreading #if IS_ENABLEDs into the code.
> > Probably enough to add a 'depends on PERF_EVENTS' to config BPF_EVENTS,
> > so it's also explicitly documented.
> > 
> 
> So just do the following then?
> 
> -- Steve
> 
> diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
> index 8d6363f42169..f5aecff2d243 100644
> --- a/kernel/trace/Kconfig
> +++ b/kernel/trace/Kconfig
> @@ -434,7 +434,7 @@ config UPROBE_EVENT
>  
>  config BPF_EVENTS
>  	depends on BPF_SYSCALL
> -	depends on KPROBE_EVENT || UPROBE_EVENT
> +	depends on KPROBE_EVENT && UPROBE_EVENT

yeah that's definitely cleaner and avoids ifdef creep in the future.

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#1266659

On 11/10/2015 06:14 PM, Alexei Starovoitov wrote:
> On Tue, Nov 10, 2015 at 09:25:01AM -0500, Steven Rostedt wrote:
>> On Tue, 10 Nov 2015 14:31:38 +0100
>> Daniel Borkmann <daniel@iogearbox.net> wrote:
>>
>>> On 11/10/2015 01:55 PM, Arnd Bergmann wrote:
>>>> In my ARM randconfig tests, I'm getting a build error for
>>>> newly added code in bpf_perf_event_read and bpf_perf_event_output
>>>> whenever CONFIG_PERF_EVENTS is disabled:
>>>>
>>>> kernel/trace/bpf_trace.c: In function 'bpf_perf_event_read':
>>>> kernel/trace/bpf_trace.c:203:11: error: 'struct perf_event' has no member named 'oncpu'
>>>> if (event->oncpu != smp_processor_id() ||
>>>>            ^
>>>> kernel/trace/bpf_trace.c:204:11: error: 'struct perf_event' has no member named 'pmu'
>>>>         event->pmu->count)
>>>>
>>>> This can happen when UPROBE_EVENT is enabled but KPROBE_EVENT
>>>> is disabled. I'm not sure if that is a configuration we care
>>>> about, otherwise we could prevent this case from occuring by
>>>> adding Kconfig dependencies.
>>>
>>> I think that seems better than spreading #if IS_ENABLEDs into the code.
>>> Probably enough to add a 'depends on PERF_EVENTS' to config BPF_EVENTS,
>>> so it's also explicitly documented.
>>>
>>
>> So just do the following then?
>>
>> -- Steve
>>
>> diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
>> index 8d6363f42169..f5aecff2d243 100644
>> --- a/kernel/trace/Kconfig
>> +++ b/kernel/trace/Kconfig
>> @@ -434,7 +434,7 @@ config UPROBE_EVENT
>>
>>   config BPF_EVENTS
>>   	depends on BPF_SYSCALL
>> -	depends on KPROBE_EVENT || UPROBE_EVENT
>> +	depends on KPROBE_EVENT && UPROBE_EVENT
>
> yeah that's definitely cleaner and avoids ifdef creep in the future.

Agreed, that's better.
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