Re: [PATCH v10 18/18] x86/insn-eval: Incorporate segment base in linear address computation

Ricardo Neri
2017-11-01T19:10:26Z

On Wed, Nov 01, 2017 at 06:56:42PM +0100, Borislav Petkov wrote:
> On Fri, Oct 27, 2017 at 01:25:45PM -0700, Ricardo Neri wrote:
> > insn_get_addr_ref() returns the effective address as defined by the
> > section 3.7.5.1 Vol 1 of the Intel 64 and IA-32 Architectures Software
> > Developer's Manual. In order to compute the linear address, we must add
> > to the effective address the segment base address as set in the segment
> > descriptor. The segment descriptor to use depends on the register used as
> > operand and segment override prefixes, if any.
> >
> > In most cases, the segment base address will be 0 if the USER_DS/USER32_DS
> > segment is used or if segmentation is not used. However, the base address
> > is not necessarily zero if a user programs defines its own segments. This
> > is possible by using a local descriptor table.
> >
> > Since the effective address is a signed quantity, the unsigned segment
> > base address is saved in a separate variable and added to the final,
> > unsigned, effective address.
> >
> > 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 | 55 +++++++++++++++++++++++++++++++++++++++++++++---
> > 1 file changed, 52 insertions(+), 3 deletions(-)
>
> Reviewed-by: Borislav Petkov <bp@suse.de>

Thank you Borislav! This should complete tne review of this series. As proposed
earier [1], I guess that, if the tip maintainers are OK, this series can be merged
in the tip tree?

BR,
Ricardo

[1]. https://lkml.org/lkml/2017/10/20/851