On Mon, 2017-07-31 at 10:58 +1000, Matt Brown wrote:
> This patch adds emulation of the cmpb instruction, enabling xmon to
> emulate this instruction.
> Tested for correctness against the cmpb asm instruction on ppc64le.
>
> Signed-off-by: Matt Brown <matthew.brown....@gmail.com>
Reviewed-by: Cyril Bur <cyril...@gmail.com>
> ---
> v2:
> - fixed opcode
> - fixed mask typecasting
> ---
> arch/powerpc/lib/sstep.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
> index 33117f8..87d277f 100644
> --- a/arch/powerpc/lib/sstep.c
> +++ b/arch/powerpc/lib/sstep.c
> @@ -596,6 +596,22 @@ static nokprobe_inline void do_cmp_unsigned(struct
> pt_regs *regs, unsigned long
> regs->ccr = (regs->ccr & ~(0xf << shift)) | (crval << shift);
> }
>
> +static nokprobe_inline void do_cmpb(struct pt_regs *regs, unsigned long v1,
> + unsigned long v2, int rd)
> +{
> + unsigned long long out_val, mask;
> + int i;
> +
> + out_val = 0;
> + for (i = 0; i < 8; i++) {
> + mask = 0xffUL << (i * 8);
> + if ((v1 & mask) == (v2 & mask))
> + out_val |= mask;
> + }
> +
> + regs->gpr[rd] = out_val;
> +}
> +
> static nokprobe_inline int trap_compare(long v1, long v2)
> {
> int ret = 0;
> @@ -1049,6 +1065,10 @@ int analyse_instr(struct instruction_op *op, struct
> pt_regs *regs,
> do_cmp_unsigned(regs, val, val2, rd >> 2);
> goto instr_done;
>
> + case 508: /* cmpb */
> + do_cmpb(regs, regs->gpr[rd], regs->gpr[rb], ra);
> + goto instr_done;
> +
> /*
> * Arithmetic instructions
> */
