Messages in this thread | | | Date | Wed, 01 Jul 2009 17:58:52 -0400 | From | Masami Hiramatsu <> | Subject | Re: [BUGFIX PATCH] x86: Fix fixmap page order for FIX_TEXT_POKE0,1 |
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Mathieu Desnoyers wrote: > Masami wrote : > >> Since the fixmap pages are assigned higher address to lower, text_poke() >> has to use it with inverted order (FIX_TEXT_POKE1 to FIX_TEXT_POKE0). > > I prefer to just invert the order of the fixmap declaration. It's simpler and > more straightforward.
It's ok for me too.
> Backward fixmaps seems to be used by both x86 32 and 64. > > It's a really nasty bug, because it only hurts when instructions to patch are > crossing a page boundary. If this happens, the fixmap write accesses > will spill on the following fixmap, which may very well crash the > system. And this does not crash the system, it could leave illegal > instructions in place. Thanks Masami for finding this. > > It seems to have crept into the 2.6.30-rc series, so this calls for a > -stable inclusion.
Right, thanks.
> > Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: Masami Hiramatsu <mhiramat@redhat.com>
> Cc: Ingo Molnar <mingo@elte.hu> > CC: stable@kernel.org > --- > arch/x86/include/asm/fixmap.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > Index: linux-2.6-lttng/arch/x86/include/asm/fixmap.h > =================================================================== > --- linux-2.6-lttng.orig/arch/x86/include/asm/fixmap.h 2009-07-01 16:52:57.000000000 -0400 > +++ linux-2.6-lttng/arch/x86/include/asm/fixmap.h 2009-07-01 16:54:52.000000000 -0400 > @@ -111,8 +111,8 @@ enum fixed_addresses { > #ifdef CONFIG_PARAVIRT > FIX_PARAVIRT_BOOTMAP, > #endif > - FIX_TEXT_POKE0, /* reserve 2 pages for text_poke() */ > - FIX_TEXT_POKE1, > + FIX_TEXT_POKE1, /* reserve 2 pages for text_poke() */ > + FIX_TEXT_POKE0, /* first page is last, because allocation is backward */ > __end_of_permanent_fixed_addresses, > #ifdef CONFIG_PROVIDE_OHCI1394_DMA_INIT > FIX_OHCI1394_BASE, >
-- Masami Hiramatsu
Software Engineer Hitachi Computer Products (America), Inc. Software Solutions Division
e-mail: mhiramat@redhat.com
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