On Mon, 2017-07-31 at 10:58 +1000, Matt Brown wrote:
> This adds emulation for the isel instruction.
> Tested for correctness against the isel instruction and its extended
> mnemonics (lt, gt, eq) on ppc64le.
>
> Signed-off-by: Matt Brown <matthew.brown....@gmail.com>
Reviewed-by: Cyril Bur <cyril...@gmail.com>
> ---
> v4:
> - simplify if statement to ternary op
> (same as isel emulation in kernel/traps.c)
> v2:
> - fixed opcode
> - fixed definition to include the 'if RA=0, a=0' clause
> - fixed ccr bitshifting error
> ---
> arch/powerpc/lib/sstep.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
> index af4eef9..473bab5 100644
> --- a/arch/powerpc/lib/sstep.c
> +++ b/arch/powerpc/lib/sstep.c
> @@ -1240,6 +1240,14 @@ int analyse_instr(struct instruction_op *op, struct
> pt_regs *regs,
> /*
> * Logical instructions
> */
> + case 15: /* isel */
> + mb = (instr >> 6) & 0x1f; /* bc */
> + val = (regs->ccr >> (31 - mb)) & 1;
> + val2 = (ra) ? regs->gpr[ra] : 0;
> +
> + regs->gpr[rd] = (val) ? val2 : regs->gpr[rb];
> + goto logical_done;
> +
> case 26: /* cntlzw */
> asm("cntlzw %0,%1" : "=r" (regs->gpr[ra]) :
> "r" (regs->gpr[rd]));
