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SubjectRe: [PATCH] x86/fpu: move FPU state into separate cache
On 03/29/17 13:39, Kees Cook wrote:
> This removes ARCH_WANTS_DYNAMIC_TASK_STRUCT from x86, leaving only s390
> still defining this config.
> In order to support future structure layout randomization of the
> task_struct, none of the structure fields are allowed to have a specific
> position or dynamic size. To enable randomization of task_struct on
> x86, the FPU state must be moved to its own dynamically sized cache,
> and dereferenced from the task_struct.
> This change is nearly identical to what was done in grsecurity to support
> structure layout randomization. Hopefully I found all the needed changes.
> This passes allyesconfig, and boot tests.

Is this really what we want to happen? It seems much more sane to
simply make them adjacent; they don't need to be part of the same
structure (in practice, there are three objects: thread_info,
task_struct, and the FPU state.)


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