From: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Rabin Vincent <rabin@rab.in>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Peter Zijlstra <peterz@infradead.org>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Subject: Re: [PATCH 6/9] uprobes: flush cache after xol write
Date: Fri, 26 Oct 2012 11:22:39 +0530 [thread overview]
Message-ID: <20121026055239.GA4862@in.ibm.com> (raw)
In-Reply-To: <20121025145839.GB26929@redhat.com>
On Thu, Oct 25, 2012 at 04:58:39PM +0200, Oleg Nesterov wrote:
> On 10/16, Rabin Vincent wrote:
> >
> > 2012/10/15 Oleg Nesterov <oleg@redhat.com>:
> > > On 10/14, Rabin Vincent wrote:
> > >> Flush the cache so that the instructions written to the XOL area are
> > >> visible.
> > >>
> > >> Signed-off-by: Rabin Vincent <rabin@rab.in>
> > >> ---
> > >> kernel/events/uprobes.c | 1 +
> > >> 1 file changed, 1 insertion(+)
> > >>
> > >> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> > >> index ca000a9..8c52f93 100644
> > >> --- a/kernel/events/uprobes.c
> > >> +++ b/kernel/events/uprobes.c
> > >> @@ -1246,6 +1246,7 @@ static unsigned long xol_get_insn_slot(struct uprobe *uprobe, unsigned long slot
> > >> offset = current->utask->xol_vaddr & ~PAGE_MASK;
> > >> vaddr = kmap_atomic(area->page);
> > >> arch_uprobe_xol_copy(&uprobe->arch, vaddr + offset);
> > >> + flush_dcache_page(area->page);
> > >> kunmap_atomic(vaddr);
> > >
> > > I agree... but why under kmap_atomic?
> >
> > No real reason; I'll move it to after the unmap.
>
> OK. I assume you will send v2.
>
> But this patch looks like a bugfix, flush_dcache_page() is not a nop
> on powerpc. So perhaps we should apply this fix right now?
Starting Power5, all Power processers have coherent caches.
> OTOH, I do not understand this stuff, everything is nop on x86. And
> when I look into Documentation/cachetlb.txt I am starting to think
> that may be this needs flush_icache_user_range instead?
>
> Rabin, Ananth could you clarify this?
Yes. We need flush_icache_user_range(). Though for x86 its always been a
nop, one never knows if there is some Power4 or older machine out there
that is still being used. We are fine for Power5 and later.
Ananth
next prev parent reply other threads:[~2012-10-26 5:52 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-14 19:23 [PATCH 1/9] uprobes: move function declarations out of arch Rabin Vincent
2012-10-14 19:23 ` [PATCH 2/9] uprobes: check for single step support Rabin Vincent
2012-10-17 16:40 ` Srikar Dronamraju
2012-10-17 17:02 ` Oleg Nesterov
2012-10-14 19:23 ` [PATCH 3/9] uprobes: allow ignoring of probe hits Rabin Vincent
2012-10-15 16:52 ` Oleg Nesterov
2012-10-16 20:11 ` Rabin Vincent
2012-10-17 17:35 ` Oleg Nesterov
2012-10-21 18:15 ` Rabin Vincent
2012-10-21 19:40 ` Oleg Nesterov
2012-10-17 16:52 ` Srikar Dronamraju
2012-10-14 19:23 ` [PATCH 4/9] uprobes: allow arch access to xol slot Rabin Vincent
2012-10-17 17:17 ` Srikar Dronamraju
2012-10-14 19:23 ` [PATCH 5/9] uprobes: allow arch-specific initialization Rabin Vincent
2012-10-18 9:39 ` Srikar Dronamraju
2012-10-14 19:23 ` [PATCH 6/9] uprobes: flush cache after xol write Rabin Vincent
2012-10-15 16:57 ` Oleg Nesterov
2012-10-16 20:29 ` Rabin Vincent
2012-10-25 14:58 ` Oleg Nesterov
2012-10-26 5:52 ` Ananth N Mavinakayanahalli [this message]
2012-10-26 16:39 ` Oleg Nesterov
2012-10-29 5:35 ` Ananth N Mavinakayanahalli
2012-11-03 16:33 ` Oleg Nesterov
2012-11-04 14:29 ` Ananth N Mavinakayanahalli
2012-11-14 17:37 ` Oleg Nesterov
2012-10-14 19:23 ` [PATCH 7/9] uprobes: add arch write opcode hook Rabin Vincent
2012-10-14 19:23 ` [PATCH 8/9] ARM: support uprobe handling Rabin Vincent
2012-11-04 10:13 ` Russell King - ARM Linux
2012-11-12 17:26 ` Rabin Vincent
2012-10-14 19:23 ` [PATCH 9/9] ARM: add uprobes support Rabin Vincent
2012-10-15 11:14 ` Dave Martin
2012-10-15 11:44 ` Rabin Vincent
2012-10-15 17:44 ` Dave Martin
2012-10-17 14:50 ` Jon Medhurst (Tixy)
2012-10-21 18:43 ` Rabin Vincent
2012-10-21 18:59 ` Rabin Vincent
2012-10-15 17:31 ` Dave Martin
2012-10-21 18:27 ` Rabin Vincent
2012-10-17 17:54 ` Oleg Nesterov
2012-10-15 17:19 ` [PATCH 1/9] uprobes: move function declarations out of arch Srikar Dronamraju
2012-10-16 20:30 ` Rabin Vincent
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