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From: Jann Horn <jannh@google.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	"the arch/x86 maintainers" <x86@kernel.org>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Alexander Potapenko <glider@google.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	kasan-dev <kasan-dev@googlegroups.com>,
	kernel list <linux-kernel@vger.kernel.org>,
	Andrey Konovalov <andreyknvl@google.com>,
	Andy Lutomirski <luto@kernel.org>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH v3 2/4] x86/traps: Print non-canonical address on #GP
Date: Wed, 20 Nov 2019 13:42:31 +0100	[thread overview]
Message-ID: <CAG48ez11KVxQoSDM2GmMAxU=1jNZNYKcLFkvpkeq74p+yxeefw@mail.gmail.com> (raw)
In-Reply-To: <20191120123926.GE2634@zn.tnic>

On Wed, Nov 20, 2019 at 1:39 PM Borislav Petkov <bp@alien8.de> wrote:
> On Wed, Nov 20, 2019 at 01:30:58PM +0100, Ingo Molnar wrote:
> > * Jann Horn <jannh@google.com> wrote:
> >
> > > You mean something like this?
> > >
> > > ========================
> > > diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
> > > index 9b23c4bda243..16a6bdaccb51 100644
> > > --- a/arch/x86/kernel/traps.c
> > > +++ b/arch/x86/kernel/traps.c
> > > @@ -516,32 +516,36 @@ dotraplinkage void do_bounds(struct pt_regs
> > > *regs, long error_code)
> > >   * On 64-bit, if an uncaught #GP occurs while dereferencing a non-canonical
> > >   * address, return that address.
> > >   */
> > > -static unsigned long get_kernel_gp_address(struct pt_regs *regs)
> > > +static bool get_kernel_gp_address(struct pt_regs *regs, unsigned long *addr,
> > > +                                          bool *non_canonical)
> >
> > Yeah, that's pretty much the perfect end result!
>
> Why do we need the bool thing? Can't we rely on the assumption that an
> address of 0 is the error case and use that to determine whether the
> resolving succeeded or not?

True, that'd work, too. I didn't really want to special-case an
integer here - especially one that has the same value as NULL - but I
guess it's fine.

  reply	other threads:[~2019-11-20 12:43 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-20 10:36 [PATCH v3 1/4] x86/insn-eval: Add support for 64-bit kernel mode Jann Horn
2019-11-20 10:36 ` [PATCH v3 2/4] x86/traps: Print non-canonical address on #GP Jann Horn
2019-11-20 11:18   ` Ingo Molnar
2019-11-20 11:24     ` Borislav Petkov
2019-11-20 12:25       ` Jann Horn
2019-11-20 12:41         ` Borislav Petkov
2019-11-20 13:16         ` Ingo Molnar
2019-11-20 13:23           ` Jann Horn
2019-11-20 14:05             ` Ingo Molnar
2019-11-20 12:14     ` Jann Horn
2019-11-20 12:30       ` Ingo Molnar
2019-11-20 12:39         ` Borislav Petkov
2019-11-20 12:42           ` Jann Horn [this message]
2019-11-20 13:28           ` Ingo Molnar
2019-11-20 13:39             ` Borislav Petkov
2019-11-20 16:21               ` Sean Christopherson
2019-11-20 17:37                 ` Borislav Petkov
2019-11-20 10:36 ` [PATCH v3 3/4] x86/dumpstack: Split out header line printing from __die() Jann Horn
2019-11-20 10:36 ` [PATCH v3 4/4] x86/kasan: Print original address on #GP Jann Horn

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