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SubjectRe: [PATCH 4/6] kvm, emulator: Add initial three-byte insns support
On Sun, Sep 22, 2013 at 04:44:53PM +0200, Borislav Petkov wrote:
> From: Borislav Petkov <bp@suse.de>
>
> Add initial support for handling three-byte instructions in the
> emulator.
>
> Signed-off-by: Borislav Petkov <bp@suse.de>
> ---
> arch/x86/kvm/emulate.c | 30 ++++++++++++++++++++++++++++++
> 1 file changed, 30 insertions(+)
>
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index 67277bcb377a..72093d76c769 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -3880,6 +3880,25 @@ static const struct opcode twobyte_table[256] = {
> N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N
> };
>
> +static const struct gprefix third_opcode_byte_0xf0 = {
> + N, N, N, N
> +};
> +
> +static const struct gprefix third_opcode_byte_0xf1 = {
> + N, N, N, N
> +};
There are two three opcode tables, so third_opcode_byte is ambiguous.
What about pfx_0f_38_f0 and pfx_0f_38_f1?

> +
> +/*
> + * Insns below are selected by the prefix which indexed by the third opcode
> + * byte.
> + */
> +static const struct opcode opcode_map_0f_38[256] = {
> + /* 0x00 - 0x7f */
> + X16(N), X16(N), X16(N), X16(N), X16(N), X16(N), X16(N), X16(N),
> + /* 0x80 - 0xff */
> + X16(N), X16(N), X16(N), X16(N), X16(N), X16(N), X16(N), X16(N)
> +};
> +
> #undef D
> #undef N
> #undef G
> @@ -4200,6 +4219,13 @@ done_prefixes:
> ctxt->opcode_len = 2;
> ctxt->b = insn_fetch(u8, ctxt);
> opcode = twobyte_table[ctxt->b];
> +
> + /* 0F_38 opcode map */
> + if (ctxt->b == 0x38) {
> + ctxt->opcode_len = 3;
> + ctxt->b = insn_fetch(u8, ctxt);
> + opcode = opcode_map_0f_38[ctxt->b];
> + }
> }
> ctxt->d = opcode.flags;
>
> @@ -4531,6 +4557,8 @@ special_insn:
>
> if (ctxt->opcode_len == 2)
> goto twobyte_insn;
> + else if (ctxt->opcode_len == 3)
> + goto threebyte_insn;
>
> switch (ctxt->b) {
> case 0x63: /* movsxd */
> @@ -4715,6 +4743,8 @@ twobyte_insn:
> goto cannot_emulate;
> }
>
> +threebyte_insn:
> +
> if (rc != X86EMUL_CONTINUE)
> goto done;
>
> --
> 1.8.4

--
Gleb.


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