On Fri, Mar 1, 2019 at 2:35 AM Peter Zijlstra wrote:
>
> With the dodgy patch:
>
> CC drivers/gpu/drm/i915/i915_gem_execbuffer.o
> drivers/gpu/drm/i915/i915_gem_execbuffer.o: warning: objtool:
> eb_relocate_slow()+0x1f9: call to kvfree() with UACCESS enabled
> drivers/gpu/drm/i915/i915_gem_e
On Fri, Mar 1, 2019 at 4:57 AM Peter Zijlstra wrote:
>
> Or.. we move the thing to assembly. Of course, I suck at (writing) asm,
> so the below is probably broken in various ways.
Looks sane, and makes sense. I feel that the old "mixed C and asm" was
much worse.
My only comment is that I think y
> On Mar 1, 2019, at 6:38 AM, Peter Zijlstra wrote:
>
>> On Fri, Mar 01, 2019 at 01:57:18PM +0100, Peter Zijlstra wrote:
>>> On Fri, Mar 01, 2019 at 01:27:45PM +0100, Peter Zijlstra wrote:
>>> arch/x86/lib/usercopy_64.o: warning: objtool: .altinstr_replacement+0x30:
>>> redundant UACCESS disa
On Fri, Mar 01, 2019 at 01:57:18PM +0100, Peter Zijlstra wrote:
> On Fri, Mar 01, 2019 at 01:27:45PM +0100, Peter Zijlstra wrote:
> > arch/x86/lib/usercopy_64.o: warning: objtool: .altinstr_replacement+0x30:
> > redundant UACCESS disable
>
> > The usercopy one is difficult, that's copy_user_handl
On Fri, Mar 01, 2019 at 01:27:45PM +0100, Peter Zijlstra wrote:
> arch/x86/lib/usercopy_64.o: warning: objtool: .altinstr_replacement+0x30:
> redundant UACCESS disable
> The usercopy one is difficult, that's copy_user_handle_tail(), it is
> buggered though, because that lacks notrace and thus has
On Fri, Mar 01, 2019 at 11:34:52AM +0100, Peter Zijlstra wrote:
> Let me do an allmodconfig build to see how much pain is caused by that
> redundant CLAC warning.
arch/x86/lib/usercopy_64.o: warning: objtool: .altinstr_replacement+0x30:
redundant UACCESS disable
drivers/gpu/drm/i915/i915_gem_exe
On Thu, Feb 28, 2019 at 08:01:11PM +0100, Peter Zijlstra wrote:
> On Thu, Feb 28, 2019 at 10:29:25AM -0800, Linus Torvalds wrote:
> > On Thu, Feb 28, 2019 at 10:02 AM Peter Zijlstra
> > wrote:
> > >
> > > Weird, that jump is from C, not from a .fixup table. objtool _should_
> > > see that and com
On Thu, Feb 28, 2019 at 10:29:25AM -0800, Linus Torvalds wrote:
> On Thu, Feb 28, 2019 at 10:02 AM Peter Zijlstra wrote:
> >
> > Weird, that jump is from C, not from a .fixup table. objtool _should_
> > see that and complain if there is a AC=1 path that reaches RET.
>
> No, unsafe_put_user() actu
On Thu, Feb 28, 2019 at 10:02 AM Peter Zijlstra wrote:
>
> Weird, that jump is from C, not from a .fixup table. objtool _should_
> see that and complain if there is a AC=1 path that reaches RET.
No, unsafe_put_user() actually does the "asm goto" thing, so the jump
is literally hidden as an except
On Thu, Feb 28, 2019 at 06:51:14PM +0100, Peter Zijlstra wrote:
> On Thu, Feb 28, 2019 at 08:49:57AM -0800, Linus Torvalds wrote:
> > Yes, it is redundant (but harmlessly so) if no fault occurs.
>
> Oooh, there's a label hidden in unsafe_put_user()...
>
> And yes, objtool seems to miss that, damn
On Thu, Feb 28, 2019 at 08:49:57AM -0800, Linus Torvalds wrote:
> Yes, it is redundant (but harmlessly so) if no fault occurs.
Oooh, there's a label hidden in unsafe_put_user()...
And yes, objtool seems to miss that, damn. I'll go stare at that.
On Thu, Feb 28, 2019 at 7:05 AM Peter Zijlstra wrote:
>
> drivers/gpu/drm/i915/i915_gem_execbuffer.o: warning: objtool:
> .altinstr_replacement+0x3c: redundant UACCESS disable
> drivers/gpu/drm/i915/i915_gem_execbuffer.o: warning: objtool:
> .altinstr_replacement+0x66: redundant UACCESS disable
On Thu, Feb 28, 2019 at 03:10:44PM +, Chris Wilson wrote:
> Quoting Peter Zijlstra (2019-02-28 14:54:56)
> > drivers/gpu/drm/i915/i915_gem_execbuffer.o: warning: objtool:
> > .altinstr_replacement+0x3c: redundant UACCESS disable
> > drivers/gpu/drm/i915/i915_gem_execbuffer.o: warning: objtool:
Quoting Peter Zijlstra (2019-02-28 14:54:56)
> drivers/gpu/drm/i915/i915_gem_execbuffer.o: warning: objtool:
> .altinstr_replacement+0x3c: redundant UACCESS disable
> drivers/gpu/drm/i915/i915_gem_execbuffer.o: warning: objtool:
> .altinstr_replacement+0x66: redundant UACCESS disable
>
> AKA. yo
drivers/gpu/drm/i915/i915_gem_execbuffer.o: warning: objtool:
.altinstr_replacement+0x3c: redundant UACCESS disable
drivers/gpu/drm/i915/i915_gem_execbuffer.o: warning: objtool:
.altinstr_replacement+0x66: redundant UACCESS disable
AKA. you don't need user_access_end() if user_access_begin() fai
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