On Fri, 2017-01-27 at 16:53 +0900, Masami Hiramatsu wrote:
> On Wed, 25 Jan 2017 22:07:16 -0800
> Ricardo Neri <ricardo.neri-calderon@xxxxxxxxxxxxxxx> wrote:
>
> > Hi Masami,
> >
> > On Thu, 2017-01-26 at 11:11 +0900, Masami Hiramatsu wrote:
> > > On Wed, 25 Jan 2017 12:23:47 -0800
> > > Ricardo Neri <ricardo.neri-calderon@xxxxxxxxxxxxxxx> wrote:
> > >
> > > > The function insn_get_reg_offset requires a type to indicate whether
> > > > the returned offset is that given by by the ModRM or the SIB byte.
> > > > Callers of this function would need the definition of the type struct.
> > > > This is not needed. Instead, auxiliary functions can be defined for
> > > > this purpose.
> > > >
> > > > When the operand is a register, the emulation code for User-Mode
> > > > Instruction Prevention needs to know the offset of the register indicated
> > > > in the r/m part of the ModRM byte. Thus, start by adding an auxiliary
> > > > function for this purpose.
> > >
> > > Hmm, why wouldn't you just rename it to insn_get_reg_offset() and export it?
> >
> > Do you mean exporting the structure that I mention above? The problem
> > that I am trying to solve is that callers sometimes want to know the
> > offset of the register encoded in the SiB or the ModRM bytes. I could
> > use something
> >
> > insn_get_reg_offset(insn, regs, INSN_TYPE_MODRM)
> > insn_get_reg_offset(insn, regs, INSN_TYPE_SIB)
> >
> > Instead, I opted for
> >
> > insn_get_reg_offset_rm(insn, regs)
> > insn_get_reg_offset_sib(insn, regs)
> >
> > to avoid exposing an enum with the INSN_TYPE_MODRM, INSN_TYPE_SIB.
>
> OK, if so, I think you should export both of them at once, not only
> insn_get_reg_offset_rm().
Sure, I will include both functions.
Thanks and BR,
Ricardo
>
> Thank you,
>
> >
> > If you feel that the former makes more sense, I can change the
> > implementation.
> >
> > Thanks and BR,
> > Ricardo
> > >
> > > Thank you,
> > >
> > > >
> > > > Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> > > > Cc: Adam Buchbinder <adam.buchbinder@xxxxxxxxx>
> > > > Cc: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> > > > Cc: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
> > > > Cc: Qiaowei Ren <qiaowei.ren@xxxxxxxxx>
> > > > Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> > > > Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> > > > Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> > > > Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> > > > Cc: Thomas Garnier <thgarnie@xxxxxxxxxx>
> > > > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> > > > Cc: Borislav Petkov <bp@xxxxxxx>
> > > > Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> > > > Cc: Ravi V. Shankar <ravi.v.shankar@xxxxxxxxx>
> > > > Cc: x86@xxxxxxxxxx
> > > > Signed-off-by: Ricardo Neri <ricardo.neri-calderon@xxxxxxxxxxxxxxx>
> > > > ---
> > > > arch/x86/include/asm/insn-kernel.h | 1 +
> > > > arch/x86/lib/insn-kernel.c | 5 +++++
> > > > 2 files changed, 6 insertions(+)
> > > >
> > > > diff --git a/arch/x86/include/asm/insn-kernel.h b/arch/x86/include/asm/insn-kernel.h
> > > > index aef416a..3f34649 100644
> > > > --- a/arch/x86/include/asm/insn-kernel.h
> > > > +++ b/arch/x86/include/asm/insn-kernel.h
> > > > @@ -12,5 +12,6 @@
> > > > #include <asm/ptrace.h>
> > > >
> > > > void __user *insn_get_addr_ref(struct insn *insn, struct pt_regs *regs);
> > > > +int insn_get_reg_offset_rm(struct insn *insn, struct pt_regs *regs);
> > > >
> > > > #endif /* _ASM_X86_INSN_KERNEL_H */
> > > > diff --git a/arch/x86/lib/insn-kernel.c b/arch/x86/lib/insn-kernel.c
> > > > index 8072abe..267cab4 100644
> > > > --- a/arch/x86/lib/insn-kernel.c
> > > > +++ b/arch/x86/lib/insn-kernel.c
> > > > @@ -95,6 +95,11 @@ static int get_reg_offset(struct insn *insn, struct pt_regs *regs,
> > > > return regoff[regno];
> > > > }
> > > >
> > > > +int insn_get_reg_offset_rm(struct insn *insn, struct pt_regs *regs)
> > > > +{
> > > > + return get_reg_offset(insn, regs, REG_TYPE_RM);
> > > > +}
> > > > +
> > > > /*
> > > > * return the address being referenced be instruction
> > > > * for rm=3 returning the content of the rm reg
> > > > --
> > > > 2.9.3
> > > >
> > >
> > >
> >
> >
>
>
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