linux-kernel - Re: [PATCH 16/22] x86/fpu: Always store the registers in copy_fpstate_to

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Date:   Thu, 7 Feb 2019 14:28:07 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Borislav Petkov <bp@...en8.de>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        Andy Lutomirski <luto@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        kvm@...r.kernel.org, "Jason A. Donenfeld" <Jason@...c4.com>,
        Rik van Riel <riel@...riel.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH 16/22] x86/fpu: Always store the registers in
 copy_fpstate_to_sigframe()

On 2019-01-30 12:43:22 [+0100], Borislav Petkov wrote:
> > @@ -171,9 +156,15 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
> >  			sizeof(struct user_i387_ia32_struct), NULL,
> >  			(struct _fpstate_32 __user *) buf) ? -1 : 1;
> >  
> > -	/* Save the live register state to the user directly. */
> > -	if (copy_fpregs_to_sigframe(buf_fx))
> > -		return -1;
> > +	copy_fpregs_to_fpstate(fpu);
> > +
> > +	if (using_compacted_format()) {
> > +		copy_xstate_to_user(buf_fx, xsave, 0, size);
> > +	} else {
> > +		fpstate_sanitize_xstate(fpu);
> > +		if (__copy_to_user(buf_fx, xsave, fpu_user_xstate_size))
> > +			return -1;
> > +	}
> >  
> >  	/* Save the fsave header for the 32-bit frames. */
> >  	if ((ia32_fxstate || !use_fxsr()) && save_fsave_header(tsk, buf))
> 
> Comments above that function need updating.

Did:
- * Save the state directly to the user frame pointed by the aligned pointer
- * 'buf_fx'.
+ * Save the state to task's fpu->state and then copy it to the user frame
+ * pointed by the aligned pointer 'buf_fx'.

Sebastian