linux-kernel - Re: [v5 17/20] x86/umip: Force a page fault when unable to copy emulated result to user

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Date:   Mon, 06 Mar 2017 16:26:01 -0800
From:   Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
To:     Andy Lutomirski <luto@...capital.net>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        Borislav Petkov <bp@...e.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Brian Gerst <brgerst@...il.com>,
        Chris Metcalf <cmetcalf@...lanox.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Liang Z Li <liang.z.li@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Huang Rui <ray.huang@....com>, Jiri Slaby <jslaby@...e.cz>,
        Jonathan Corbet <corbet@....net>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Chen Yucong <slaoub@...il.com>,
        Alexandre Julliard <julliard@...ehq.org>,
        Stas Sergeev <stsp@...t.ru>, Fenghua Yu <fenghua.yu@...el.com>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Shuah Khan <shuah@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        X86 ML <x86@...nel.org>, linux-msdos@...r.kernel.org,
        wine-devel@...ehq.org
Subject: Re: [v5 17/20] x86/umip: Force a page fault when unable to copy
 emulated result to user

On Sun, 2017-03-05 at 08:18 -0800, Andy Lutomirski wrote:
> > + */
> > +static void __force_sig_info_umip_fault(void __user *address,
> > +                                       struct pt_regs *regs)
> > +{
> > +       siginfo_t info;
> > +       struct task_struct *tsk = current;
> > +
> > +       if (show_unhandled_signals && unhandled_signal(tsk,
> SIGSEGV)) {
> > +               printk_ratelimited("%s[%d] umip emulation segfault
> ip:%lx sp:%lx error:%lx in %lx\n",
> > +                                  tsk->comm, task_pid_nr(tsk),
> regs->ip,
> > +                                  regs->sp, UMIP_PF_USER |
> UMIP_PF_WRITE,
> > +                                  regs->ip);
> > +       }
> > +
> > +       tsk->thread.cr2         = (unsigned long)address;
> > +       tsk->thread.error_code  = UMIP_PF_USER | UMIP_PF_WRITE;
> 
> Please just move enum x86_pf_error_code into a header and rename the
> fields X86_PF_USER, etc rather than duplicating it.

Thanks again for your feedback! I will do this.