Enable 32-bit compat drm ioctls

[valpackett]

Fixes FreeBSDDesktop/DEPRECATED-freebsd-base-graphics#166 :)

Requires freebsd/freebsd-src@10ef676

Mostly based on importing drm_ioc32.c from current linux.
(They no longer use compat_alloc_user_space.)

Tested: on amdgpu, Wine runs 32-bit Quake II, and Steam under Linuxulator shows the login window instead of segfaulting.

Relevant Linux commits:

• torvalds/linux@7cfdf71
• torvalds/linux@7f0dfc1
• torvalds/linux@5c7640a torvalds/linux@17e3dad etc.

[jiixyj]

Thank you, this works great! I've tested this on a ThinkPad T420 with Intel Sandy Bridge graphics. But I needed to modify compat_i915_getparam in i915_ioc32.c like this:

static int compat_i915_getparam(struct file *file, unsigned int cmd,
				unsigned long arg)
{
	drm_i915_getparam_t __user *request = (void __user *)arg;
	struct drm_i915_getparam32 req32;
	struct drm_i915_getparam req;

	if (copy_from_user(&req32, request, sizeof(req32)))
		return -EFAULT;

	req.param = req32.param;
	req.value = (void *)(uintptr_t)req32.value;

	return drm_ioctl_kernel(file, i915_getparam,
			 &req, DRM_AUTH|DRM_RENDER_ALLOW);
}

[valpackett]

Oops, missed that one, only tested on amdgpu. Thanks @jiixyj :)

[jeremymcox]

I have tested these modifications to enable 32 bit drm ioctls, and it works on my Haswell GPU. Pipelight actually works with intel video! I haven't extensively tested it but it works so far. Thanks all for your hard work!

[markjdb]

This looks good to me. Thanks!