From: Linus Torvalds <torvalds@linux-foundation.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Leonid Yegoshin" <Leonid.Yegoshin@imgtec.com>,
linux-mips <linux-mips@linux-mips.org>,
Zubair.Kakakhel@imgtec.com,
"David Daney" <david.daney@cavium.com>,
"Paul Gortmaker" <paul.gortmaker@windriver.com>,
"Davidlohr Bueso" <davidlohr@hp.com>,
"Maciej W. Rozycki" <macro@linux-mips.org>,
chenhc@lemote.com, "Rafał Miłecki" <zajec5@gmail.com>,
"James Hogan" <james.hogan@imgtec.com>,
"Kees Cook" <keescook@chromium.org>,
alex@alex-smith.me.uk, "Thomas Gleixner" <tglx@linutronix.de>,
"John Crispin" <blogic@openwrt.org>,
jchandra@broadcom.com, paul.burton@imgtec.com,
qais.yousef@imgtec.com,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"Ralf Baechle" <ralf@linux-mips.org>,
markos.chandras@imgtec.com,
"Manuel Lauss" <manuel.lauss@gmail.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
lars.persson@axis.com
Subject: Re: [PATCH 0/3] MIPS executable stack protection
Date: Sat, 4 Oct 2014 09:03:53 -0700 [thread overview]
Message-ID: <CA+55aFynSp90n=jdUdmY7nq-9t4pHS82Tj-WfZOBfot7ip0hBw@mail.gmail.com> (raw)
In-Reply-To: <20141004082307.GS10583@worktop.programming.kicks-ass.net>
On Sat, Oct 4, 2014 at 1:23 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Fri, Oct 03, 2014 at 08:17:14PM -0700, Leonid Yegoshin wrote:
>> The following series implements an executable stack protection in MIPS.
>>
>> It sets up a per-thread 'VDSO' page and appropriate TLB support.
>
> So traditionally we've always avoided per-thread pages like that. What
> makes it worth it on MIPS?
Nothing makes it worth it on MIPS.
It may be easy to implement when you have all software-fill of TLB's,
but it's a mistake even then - because it means that you'll never be
able to do hardware TLB walkers.
And MIPS *does* have hardware TLB walkers, even if they are not
necessarily available everywhere.
So this is a horrible idea. Don't do it. Page tables need to be
per-process, not per thread, so that page tables can be shared.
Linus
next prev parent reply other threads:[~2014-10-04 16:03 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-04 3:17 [PATCH 0/3] MIPS executable stack protection Leonid Yegoshin
2014-10-04 3:17 ` [PATCH 1/3] MIPS: mips_flush_cache_range is added Leonid Yegoshin
2014-10-04 3:17 ` [PATCH 2/3] MIPS: Setup an instruction emulation in VDSO protected page instead of user stack Leonid Yegoshin
2014-10-04 20:00 ` Peter Zijlstra
2014-10-05 5:52 ` Leonid Yegoshin
2014-10-06 12:29 ` Paul Burton
2014-10-06 20:42 ` Leonid Yegoshin
2014-10-06 18:05 ` David Daney
2014-10-06 20:03 ` Leonid Yegoshin
2014-10-04 3:17 ` [PATCH 3/3] MIPS: set stack/data protection as non-executable Leonid Yegoshin
2014-10-04 8:23 ` [PATCH 0/3] MIPS executable stack protection Peter Zijlstra
2014-10-04 16:03 ` Linus Torvalds [this message]
2014-10-04 16:17 ` Leonid Yegoshin
2014-10-04 16:27 ` Linus Torvalds
2014-10-04 15:33 Leonid Yegoshin
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