* Borislav Petkov <[email protected]> wrote:
> From: Hector Marco-Gisbert <[email protected]>
> Date: Fri, 27 Mar 2015 12:38:21 +0100
> Subject: [PATCH] x86/mm: Improve AMD Bulldozer ASLR fix
>
> The ASLR implementation needs to special-case AMD F15h processors by
> clearing out bits [14:12] of the virtual address in order to avoid I$
> cross invalidations and thus performance penalty for certain workloads.
> For details, see:
>
> dfb09f9b7ab0 ("x86, amd: Avoid cache aliasing penalties on AMD family 15h")
>
> This special case reduces the mmapped files entropy by eight.
s/reduces the mmapped file's entropy by 3 bits
Which does:
- a grammar fix
- measure it in bits, as later on we are talking about randomness in
bits as well.
Btw., does this limitation affect both executable and non-executable
mmap()s? Because data mmap()s don't need this I$ related workaround,
right? So we could relax it for data-mmap()s?
Thanks,
Ingo
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