Messages in this thread | | | Date | Sat, 12 Feb 2011 17:10:14 +0100 | From | matthieu castet <> | Subject | Re: [PATCH] NX protection for kernel data : fix 32 bits S3 suspend |
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H. Peter Anvin a écrit : > On 02/07/2011 11:59 AM, castet.matthieu@free.fr wrote: >> For .39 I hope we could remove most of the RWX rights after init (This means >> make low memory trampoline NX or !RW). >> This should be possible on : >> - 32 bit if wakeup use trampoline_32 [1] that doesn't enable paging in low >> memory (can be NX) >> - trampoline_64 need fix to support NX on data section. It tries to read data >> section before enabling NX. A possible fix is to use its own page table [2]. And >> the kernel one can be NX. > > No, you're really barking down the wrong path on this. The trampoline > code is tiny; I don't think it is really worth trying to NX-ify it. The Even if the trampoline is tiny, a hole is a hole.
The trampoline code job is to jump from low memory (realmode) to somewhere in kernel text. Why should we enable paging or use kernel page table for doing that ?
> additional complexity caused by not being able to execute in this space > will really damage some other incoming code, so it isn't an option as > far as I'm concerned. > What do you plan to add that won't be compatible with that ?
Matthieu
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