On Tue, Dec 10, 2019 at 12:49:03PM +0530, Balamuruhan S wrote:
> This patch adds emulation support for divde, divdeu instructions,
> * Divide Doubleword Extended (divde[.])
> * Divide Doubleword Extended Unsigned (divdeu[.])
>
> Signed-off-by: Balamuruhan S <bal...@linux.ibm.com>
> ---
> arch/powerpc/lib/sstep.c | 27 ++++++++++++++++++++++++++-
> 1 file changed, 26 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
> index c077acb983a1..4b4119729e59 100644
> --- a/arch/powerpc/lib/sstep.c
> +++ b/arch/powerpc/lib/sstep.c
> @@ -1736,7 +1736,32 @@ int analyse_instr(struct instruction_op *op, const
> struct pt_regs *regs,
> op->val = (int) regs->gpr[ra] /
> (int) regs->gpr[rb];
> goto arith_done;
> -
> +#ifdef __powerpc64__
> + case 425: /* divde[.] */
> + if (instr & 1) {
> + asm volatile(PPC_DIVDE_DOT(%0, %1, %2) :
> + "=r" (op->val) : "r" (regs->gpr[ra]),
> + "r" (regs->gpr[rb]));
> + set_cr0(regs, op);
This seems unneccesarily complicated. You take the trouble to do a
"divde." instruction rather than a "divde" instruction but then don't
use the CR0 setting that the instruction did, but instead go and work
out what happens to CR0 manually in set_cr0(). Also you don't tell
the compiler that CR0 has been modified, which could lead to problems.
This case could be done much more simply like this:
case 425: /* divde[.] */
asm volatile(PPC_DIVDE(%0, %1, %2) :
"=r" (op->val) : "r" (regs->gpr[ra]),
"r" (regs->gpr[rb]));
goto arith_done;
(note, goto arith_done rather than compute_done) and similarly for the
divdeu case.
Paul.
