Messages in this thread |  | | Date | Fri, 8 Sep 2017 15:57:16 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH v8 11/28] x86/insn-eval: Add utility function to identify string instructions |
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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.hansen@linux.intel.com> > Cc: Adam Buchbinder <adam.buchbinder@gmail.com> > Cc: Colin Ian King <colin.king@canonical.com> > Cc: Lorenzo Stoakes <lstoakes@gmail.com> > Cc: Qiaowei Ren <qiaowei.ren@intel.com> > Cc: Arnaldo Carvalho de Melo <acme@redhat.com> > Cc: Masami Hiramatsu <mhiramat@kernel.org> > Cc: Adrian Hunter <adrian.hunter@intel.com> > Cc: Kees Cook <keescook@chromium.org> > Cc: Thomas Garnier <thgarnie@google.com> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Borislav Petkov <bp@suse.de> > Cc: Dmitry Vyukov <dvyukov@google.com> > Cc: Ravi V. Shankar <ravi.v.shankar@intel.com> > Cc: x86@kernel.org > Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com> > --- > arch/x86/lib/insn-eval.c | 26 ++++++++++++++++++++++++++ > 1 file changed, 26 insertions(+)
Reviewed-by: Borislav Petkov <bp@suse.de>
-- Regards/Gruss, Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --
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