On Fri, Aug 2, 2024 at 5:27 PM LIU Zhiwei <zhiwei_...@linux.alibaba.com> wrote:
>
> According to the risc-v specification:
> "FLD and FSD are only guaranteed to execute atomically if the effective
> address is naturally aligned and XLEN≥64."
>
> We currently implement fld as MO_ATOM_IFALIGN when XLEN < 64, which does
> not violate the rules. But it will hide some problems. So relax it to
> MO_ATOM_NONE.
>
> Signed-off-by: LIU Zhiwei <zhiwei_...@linux.alibaba.com>
Reviewed-by: Alistair Francis <alistair.fran...@wdc.com>
Alistair
> ---
> target/riscv/insn_trans/trans_rvd.c.inc | 18 ++++++++++++++----
> 1 file changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/target/riscv/insn_trans/trans_rvd.c.inc
> b/target/riscv/insn_trans/trans_rvd.c.inc
> index 49682292b8..8a46124f98 100644
> --- a/target/riscv/insn_trans/trans_rvd.c.inc
> +++ b/target/riscv/insn_trans/trans_rvd.c.inc
> @@ -48,11 +48,17 @@ static bool trans_fld(DisasContext *ctx, arg_fld *a)
> REQUIRE_EXT(ctx, RVD);
>
> /*
> - * Zama16b applies to loads and stores of no more than MXLEN bits defined
> - * in the F, D, and Q extensions.
> + * FLD and FSD are only guaranteed to execute atomically if the effective
> + * address is naturally aligned and XLEN≥64. Also, zama16b applies to
> + * loads and stores of no more than MXLEN bits defined in the F, D, and
> + * Q extensions.
> */
> - if ((get_xl_max(ctx) >= MXL_RV64) && ctx->cfg_ptr->ext_zama16b) {
> + if (get_xl_max(ctx) == MXL_RV32) {
> + memop |= MO_ATOM_NONE;
> + } else if (ctx->cfg_ptr->ext_zama16b) {
> memop |= MO_ATOM_WITHIN16;
> + } else {
> + memop |= MO_ATOM_IFALIGN;
> }
>
> decode_save_opc(ctx);
> @@ -71,8 +77,12 @@ static bool trans_fsd(DisasContext *ctx, arg_fsd *a)
> REQUIRE_FPU;
> REQUIRE_EXT(ctx, RVD);
>
> - if ((get_xl_max(ctx) >= MXL_RV64) && ctx->cfg_ptr->ext_zama16b) {
> + if (get_xl_max(ctx) == MXL_RV32) {
> + memop |= MO_ATOM_NONE;
> + } else if (ctx->cfg_ptr->ext_zama16b) {
> memop |= MO_ATOM_WITHIN16;
> + } else {
> + memop |= MO_ATOM_IFALIGN;
> }
>
> decode_save_opc(ctx);
> --
> 2.25.1
>
>
