Re: [PATCH 08/70] x86/insn: Add insn_get_modrm_reg_off()

Masami Hiramatsu
2020-03-27T03:58:03Z

On Thu, 19 Mar 2020 10:13:05 +0100
Joerg Roedel <joro@8bytes.org> wrote:

> From: Joerg Roedel <jroedel@suse.de>
>
> Add a function to the instruction decoder which returns the pt_regs
> offset of the register specified in the reg field of the modrm byte.
>

This looks good to me.

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>

Thank you,

> Signed-off-by: Joerg Roedel <jroedel@suse.de>
> ---
> arch/x86/include/asm/insn-eval.h | 1 +
> arch/x86/lib/insn-eval.c | 23 +++++++++++++++++++++++
> 2 files changed, 24 insertions(+)
>
> diff --git a/arch/x86/include/asm/insn-eval.h b/arch/x86/include/asm/insn-eval.h
> index b4ff3e3316d1..1e343010129e 100644
> --- a/arch/x86/include/asm/insn-eval.h
> +++ b/arch/x86/include/asm/insn-eval.h
> @@ -17,6 +17,7 @@
>
> 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);
> +int insn_get_modrm_reg_off(struct insn *insn, struct pt_regs *regs);
> unsigned long insn_get_seg_base(struct pt_regs *regs, int seg_reg_idx);
> int insn_get_code_seg_params(struct pt_regs *regs);
> int insn_fetch_from_user(struct pt_regs *regs,
> diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c
> index 1949f5258f9e..f18260a19960 100644
> --- a/arch/x86/lib/insn-eval.c
> +++ b/arch/x86/lib/insn-eval.c
> @@ -20,6 +20,7 @@
>
> enum reg_type {
> REG_TYPE_RM = 0,
> + REG_TYPE_REG,
> REG_TYPE_INDEX,
> REG_TYPE_BASE,
> };
> @@ -441,6 +442,13 @@ static int get_reg_offset(struct insn *insn, struct pt_regs *regs,
> regno += 8;
> break;
>
> + case REG_TYPE_REG:
> + regno = X86_MODRM_REG(insn->modrm.value);
> +
> + if (X86_REX_R(insn->rex_prefix.value))
> + regno += 8;
> + break;
> +
> case REG_TYPE_INDEX:
> regno = X86_SIB_INDEX(insn->sib.value);
> if (X86_REX_X(insn->rex_prefix.value))
> @@ -809,6 +817,21 @@ int insn_get_modrm_rm_off(struct insn *insn, struct pt_regs *regs)
> return get_reg_offset(insn, regs, REG_TYPE_RM);
> }
>
> +/**
> + * insn_get_modrm_reg_off() - Obtain register in reg part of the ModRM byte
> + * @insn: Instruction containing the ModRM byte
> + * @regs: Register values as seen when entering kernel mode
> + *
> + * Returns:
> + *
> + * The register indicated by the reg part of the ModRM byte. The
> + * register is obtained as an offset from the base of pt_regs.
> + */
> +int insn_get_modrm_reg_off(struct insn *insn, struct pt_regs *regs)
> +{
> + return get_reg_offset(insn, regs, REG_TYPE_REG);
> +}
> +
> /**
> * get_seg_base_limit() - obtain base address and limit of a segment
> * @insn: Instruction. Must be valid.
> --
> 2.17.1
>

--
Masami Hiramatsu <mhiramat@kernel.org>