Re: PERF_EVENT_IOC_SET_FILTER has different values based on bitness

[David Ahern]

On 10/7/14, 5:07 PM, David Ahern wrote:
> 32-bit perf binaries are not able to set filters on 64-bit kernels.
>
>     $ perf record -e  net:netif_receive_skb --filter 'name == "eth1"
>     Error: failed to set filter with 25 (Inappropriate ioctl for device)
>
> The reason is that the definition of PERF_EVENT_IOC_SET_FILTER contains
> a pointer:
>
> #define PERF_EVENT_IOC_SET_FILTER       _IOW('$', 6, char *)
>
> the size of which of course differs for 32-bit and 64-bit. This has been
> there since the original commit (6fb2915df7f07) back in 2009.
>
> Thoughts on how to fix this? Changing the definition of SET_FILTER
> breaks existing setups so that rules it out. What about something like
> this:
>
> #define PERF_EVENT_IOC_SET_FILTER_32       _IOW('$', 6, u32)
>
> and then
>
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 963bf139e2b2..c805132ac1cf 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -3714,6 +3714,7 @@ static long perf_ioctl(struct file *file, unsigned
> int cmd, unsigned long arg)
>      }
>
>      case PERF_EVENT_IOC_SET_FILTER:
> +   case PERF_EVENT_IOC_SET_FILTER_32:
>          return perf_event_set_filter(event, (void __user *)arg);
>
>      default:

Oh, PERF_EVENT_IOC_ID has the same problem:

#define PERF_EVENT_IOC_ID               _IOR('$', 7, __u64 *)

David

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