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    SubjectRe: [PATCH v7 08/26] x86/insn-eval: Add a utility function to get register offsets
    On Fri, May 05, 2017 at 11:17:06AM -0700, Ricardo Neri wrote:
    > The function get_reg_offset() returns the offset to the register the
    > argument specifies as indicated in an enumeration of type offset. Callers
    > of this function would need the definition of such enumeration. This is
    > not needed. Instead, add helper functions for this purpose. These functions
    > are useful in cases when, for instance, the caller needs to decide whether
    > the operand is a register or a memory location by looking at the rm part
    > of the ModRM byte. As of now, this is the only helper function that is
    > needed.
    >
    > 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/include/asm/insn-eval.h | 1 +
    > arch/x86/lib/insn-eval.c | 15 +++++++++++++++
    > 2 files changed, 16 insertions(+)
    >
    > diff --git a/arch/x86/include/asm/insn-eval.h b/arch/x86/include/asm/insn-eval.h
    > index 5cab1b1..7e8c963 100644
    > --- a/arch/x86/include/asm/insn-eval.h
    > +++ b/arch/x86/include/asm/insn-eval.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_modrm_rm_off(struct insn *insn, struct pt_regs *regs);
    >
    > #endif /* _ASM_X86_INSN_EVAL_H */
    > diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c
    > index 182e2ae..8b16761 100644
    > --- a/arch/x86/lib/insn-eval.c
    > +++ b/arch/x86/lib/insn-eval.c
    > @@ -97,6 +97,21 @@ static int get_reg_offset(struct insn *insn, struct pt_regs *regs,
    > return regoff[regno];
    > }
    >
    > +/**
    > + * insn_get_reg_offset_modrm_rm() - Obtain register in r/m part of ModRM byte

    That name needs to be synced with the function name below.

    > + * @insn: Instruction structure containing the ModRM byte
    > + * @regs: Structure with register values as seen when entering kernel mode
    > + *
    > + * Return: The register indicated by the r/m part of the ModRM byte. The
    > + * register is obtained as an offset from the base of pt_regs. In specific
    > + * cases, the returned value can be -EDOM to indicate that the particular value
    > + * of ModRM does not refer to a register and shall be ignored.
    > + */
    > +int insn_get_modrm_rm_off(struct insn *insn, struct pt_regs *regs)
    ^^^^^^^^^^^^^^^^^^^^

    --
    Regards/Gruss,
    Boris.

    SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
    --

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