On Fri, Aug 18, 2017 at 05:27:52PM -0700, Ricardo Neri wrote:
> String instructions are special because, in protected mode, the linear
> address is always obtained via the ES segment register in operands that
> use the (E)DI register; the DS segment register in operands that use
> the (E)SI register. Furthermore, segment override prefixes are ignored
> when calculating a linear address involving the (E)DI register; segment
> override prefixes can be used when calculating linear addresses involving
> the (E)SI register.
>
> It follows that linear addresses are calculated differently for the case of
> string instructions. The purpose of this utility function is to identify
> such instructions for callers to determine a linear address correctly.
>
> Note that this function only identifies string instructions; it does not
> determine what segment register to use in the address computation. That is
> left to callers. A subsequent commmit introduces a function to determine
> the segment register to use given the instruction, operands and
> segment override prefixes.
>
> Cc: Dave Hansen <dave.han...@linux.intel.com>
> Cc: Adam Buchbinder <adam.buchbin...@gmail.com>
> Cc: Colin Ian King <colin.k...@canonical.com>
> Cc: Lorenzo Stoakes <lstoa...@gmail.com>
> Cc: Qiaowei Ren <qiaowei....@intel.com>
> Cc: Arnaldo Carvalho de Melo <a...@redhat.com>
> Cc: Masami Hiramatsu <mhira...@kernel.org>
> Cc: Adrian Hunter <adrian.hun...@intel.com>
> Cc: Kees Cook <keesc...@chromium.org>
> Cc: Thomas Garnier <thgar...@google.com>
> Cc: Peter Zijlstra <pet...@infradead.org>
> Cc: Borislav Petkov <b...@suse.de>
> Cc: Dmitry Vyukov <dvyu...@google.com>
> Cc: Ravi V. Shankar <ravi.v.shan...@intel.com>
> Cc: x...@kernel.org
> Signed-off-by: Ricardo Neri <ricardo.neri-calde...@linux.intel.com>
> ---
> arch/x86/lib/insn-eval.c | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
Reviewed-by: Borislav Petkov <b...@suse.de>
--
Regards/Gruss,
Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284
(AG Nürnberg)
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