Re: [PATCH] MIPS FPU emulator: Fix prefx detection and COP1X function field definition

[David Daney <ddaney.cavm@gmail.com>]

On 03/06/2014 05:05 PM, Deng-Cheng Zhu wrote:
> From: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
>
> When running applications which contain the instruction "prefx" on FPU-less
> CPUs, a message "Illegal instruction" will be seen. This instruction is
> supposed to be ignored by the FPU emulator. However, its current detection
> and function field encoding are incorrect. This patch fix the issue.
>
> Reviewed-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
> Reviewed-by: Paul Burton <paul.burton@imgtec.com>
> Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>

Looks good.

Acked-by: David Daney <david.daney@cavium.com>


> ---
>   arch/mips/include/uapi/asm/inst.h | 4 ++--
>   arch/mips/math-emu/cp1emu.c       | 6 +++---
>   2 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/arch/mips/include/uapi/asm/inst.h b/arch/mips/include/uapi/asm/inst.h
> index b39ba25..0832fac 100644
> --- a/arch/mips/include/uapi/asm/inst.h
> +++ b/arch/mips/include/uapi/asm/inst.h
> @@ -163,8 +163,8 @@ enum cop1_sdw_func {
>    */
>   enum cop1x_func {
>   	lwxc1_op     =	0x00, ldxc1_op	   =  0x01,
> -	pfetch_op    =	0x07, swxc1_op	   =  0x08,
> -	sdxc1_op     =	0x09, madd_s_op	   =  0x20,
> +	swxc1_op     =  0x08, sdxc1_op	   =  0x09,
> +	pfetch_op    =	0x0f, madd_s_op	   =  0x20,
>   	madd_d_op    =	0x21, madd_e_op	   =  0x22,
>   	msub_s_op    =	0x28, msub_d_op	   =  0x29,
>   	msub_e_op    =	0x2a, nmadd_s_op   =  0x30,
> diff --git a/arch/mips/math-emu/cp1emu.c b/arch/mips/math-emu/cp1emu.c
> index 506925b..0b4e2e3 100644
> --- a/arch/mips/math-emu/cp1emu.c
> +++ b/arch/mips/math-emu/cp1emu.c
> @@ -1538,10 +1538,10 @@ static int fpux_emu(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
>   		break;
>   	}
>
> -	case 0x7:		/* 7 */
> -		if (MIPSInst_FUNC(ir) != pfetch_op) {
> +	case 0x3:
> +		if (MIPSInst_FUNC(ir) != pfetch_op)
>   			return SIGILL;
> -		}
> +
>   		/* ignore prefx operation */
>   		break;
>
>