Messages in this thread | | | From | "Bae, Chang Seok" <> | Subject | Re: [PATCH] x86/fpu: Set the corret permission value for perm.__state_perm | Date | Mon, 8 Nov 2021 16:13:58 +0000 |
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On Nov 8, 2021, at 14:28, Zhong, Yang <yang.zhong@intel.com> wrote: > > The perm.__state_perm is default xsave set features, when we request > AMX permission from application, the requested value(bit18) should be > replaced with mask value(requested | permitted), which can keep default > features there. > > Without this change, the below prctl syscall: > (1). ARCH_GET_XCOMP_PERM, the bitmask=0x202e7 > (2). set ARCH_REQ_XCOMP_PERM with XFEATURE_XTILEDATA > (3). ARCH_GET_XCOMP_PERM, the bitmask=0x40000, the correct value > should be 0x602e7 here.
Oh, bad.
> diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c > index d28829403ed0..fc1ab0116f4e 100644 > --- a/arch/x86/kernel/fpu/xstate.c > +++ b/arch/x86/kernel/fpu/xstate.c > @@ -1626,7 +1626,7 @@ static int __xstate_request_perm(u64 permitted, u64 requested) > return ret; > > /* Pairs with the READ_ONCE() in xstate_get_group_perm() */ > - WRITE_ONCE(fpu->perm.__state_perm, requested); > + WRITE_ONCE(fpu->perm.__state_perm, mask);
I think this has to update the group leader’s like: WRITE_ONCE(current->group_leader->thread.fpu.perm.__state_perm, mask);
Thanks, Chang
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