On Mon, Sep 23, 2019 at 11:20:24AM +0200, Peter Zijlstra wrote:
> On Wed, Sep 18, 2019 at 09:04:21PM -0700, Randy Dunlap wrote:
> > On 9/18/19 3:10 PM, Mark Brown wrote:
> > > Hi all,
> > >
> > > Changes since 20190917:
> > >
> >
> > on x86_64:
> >
> > drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: i915_gem_execbuffer2_ioctl()+0x2fb: call to gen8_canonical_addr() with UACCESS enabled
>
> I'm thinking that comes from:
>
> offset = gen8_canonical_addr(offset & ~UPDATE);
> if (unlikely(__put_user(offset, &urelocs[r-stack].presumed_offset))) {
>
> however, per commit 6ae865615fc4 (and 2a418cf3f5f1) the compiler really
> should not be sticking gen8_canonical_addr() after __uaccess_begin().
>
> /me puzzled...
I think you're looking at the wrong code. It has user_access_begin/end
around it:
if (!user_access_begin(user_exec_list, count * sizeof(*user_exec_list)))
goto end;
for (i = 0; i < args->buffer_count; i++) {
if (!(exec2_list[i].offset & UPDATE))
continue;
exec2_list[i].offset =
gen8_canonical_addr(exec2_list[i].offset & PIN_OFFSET_MASK);
unsafe_put_user(exec2_list[i].offset,
&user_exec_list[i].offset,
end_user);
}
end_user:
user_access_end();
--
Josh
