Messages in this thread |  | | Subject | Re: [PATCH v8 11/28] x86/insn-eval: Add utility function to identify string instructions | From | Ricardo Neri <> | Date | Thu, 14 Sep 2017 11:30:47 -0700 |
| |
On Fri, 2017-09-08 at 15:57 +0200, Borislav Petkov wrote: > 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>
Thanks for your review!
BR, Ricardo
|  |