Re: [PATCH] perf: Handle compat ioctl

From: Peter Zijlstra
Date: Tue Jun 17 2014 - 08:13:48 EST


On Fri, Jun 13, 2014 at 04:03:32PM +0100, Pawel Moll wrote:
> When running a 32-bit userspace on a 64-bit kernel (eg. i386
> application on x86_64 kernel or 32-bit arm userspace on arm64
> kernel) some of the perf ioctls must be treated with special
> care, as they have a pointer size encoded in the command.
>
> For example, PERF_EVENT_IOC_ID in 32-bit world will be encoded
> as 0x80042407, but 64-bit kernel will expect 0x80082407. In
> result the ioctl will fail returning -ENOTTY.
>
> This patch solves the problem by adding code fixing up the
> size as compat_ioctl file operation.
>
> Reported-by: Drew Richardson <drew.richardson@xxxxxxx>
> Signed-off-by: Pawel Moll <pawel.moll@xxxxxxx>
> ---

This gets me (on my favourite x86_64 .config):

kernel/events/core.c: In function âperf_compat_ioctlâ:
kernel/events/core.c:3726:32: error: âcompat_uptr_tâ undeclared (first use in this function)
kernel/events/core.c:3726:32: note: each undeclared identifier is reported only once for each function it appears in

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