From: rabin@rab.in (Rabin Vincent)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v5 3/8] arm: fixmap: implement __set_fixmap()
Date: Mon, 8 Sep 2014 23:55:06 +0200 [thread overview]
Message-ID: <20140908215506.GA4759@dator> (raw)
In-Reply-To: <20140908191634.GV5598@outflux.net>
On Mon, Sep 08, 2014 at 12:16:34PM -0700, Kees Cook wrote:
> On Thu, Sep 04, 2014 at 06:27:48PM +0100, Will Deacon wrote:
> > On Thu, Sep 04, 2014 at 06:23:42PM +0100, Kees Cook wrote:
> > > Ah! If this is the case, perhaps we can get away with
> > > local_flush_tlb_kernel_range() then?
> >
> > That's a bit tricky, since you need to ensure that preemption is disabled
> > until the mapping is put back like it was.
>
> Okay, under both real hardware with the errata, and under QEMU, things seem
> to work with this change to the series. What do you think?
Preemption is already disabled until the mapping is put back in this
patch.c code because interrupts are disabled from before the time
set_fixmap() is called until after clear_fixmap() is called.
I'd guess that Will meant other (future) callers of set_fixmap() would
have to ensure similar behaviour with set_fixmap() / clear_fixmap().
Unless I'm missing something set/clear_fixmap() seem to be quite arch
specific and only really used on x86, so we could ensure that future
users on ARM perform the correct tlb flush: the first user on ARM with
a non-atomic context (or you) could implement a set_fixmap() which does
the global flush and have this patch.c (and any other atomic context
callers) call __set_fixmap() directly.
The change to local_flush_tlb_kernel_range() in __set_fixmap() would of
course be needed in that case, and IIRC that was what my original patch
had (via set_top_pte()).
next prev parent reply other threads:[~2014-09-08 21:55 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-03 21:57 [PATCH v5 0/8] arm: support CONFIG_RODATA Kees Cook
2014-09-03 21:57 ` [PATCH v5 1/8] arm: use generic fixmap.h Kees Cook
2014-09-03 21:57 ` [PATCH v5 2/8] ARM: expand fixmap region to 3MB Kees Cook
2014-09-03 21:57 ` [PATCH v5 3/8] arm: fixmap: implement __set_fixmap() Kees Cook
2014-09-04 17:03 ` Will Deacon
2014-09-04 17:23 ` Kees Cook
2014-09-04 17:27 ` Will Deacon
2014-09-05 19:41 ` Kees Cook
2014-09-08 10:39 ` Will Deacon
2014-09-08 18:38 ` Kees Cook
2014-09-08 19:16 ` Kees Cook
2014-09-08 21:55 ` Rabin Vincent [this message]
2014-09-08 22:40 ` Kees Cook
2014-09-09 12:38 ` Will Deacon
2014-09-09 14:33 ` Kees Cook
2014-09-10 17:51 ` Will Deacon
2014-09-11 15:27 ` Kees Cook
2014-09-11 16:05 ` Kees Cook
2014-09-11 16:16 ` Will Deacon
2014-09-11 16:27 ` Kees Cook
2014-09-03 21:57 ` [PATCH v5 4/8] arm: use fixmap for text patching when text is RO Kees Cook
2014-09-03 21:57 ` [PATCH v5 5/8] ARM: kexec: Make .text R/W in machine_kexec Kees Cook
2014-09-03 21:57 ` [PATCH v5 6/8] arm: kgdb: Handle read-only text / modules Kees Cook
2014-09-03 21:57 ` [PATCH v5 7/8] ARM: mm: allow non-text sections to be non-executable Kees Cook
2014-09-03 21:57 ` [PATCH v5 8/8] ARM: mm: allow text and rodata sections to be read-only Kees Cook
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