[dpdk-stable] [dpdk-dev] [PATCH v3 4/5] common/octeontx2: fix build with sve enabled

[Jerin Jacob]

On Tue, Jan 12, 2021 at 8:28 AM Ruifeng Wang <ruifeng.wang at arm.com> wrote:
>
> Building with gcc 10.2 with SVE extension enabled got error:
>
> {standard input}: Assembler messages:
> {standard input}:4002: Error: selected processor does not support `mov z3.b,#0'
> {standard input}:4003: Error: selected processor does not support `whilelo p1.b,xzr,x7'
> {standard input}:4005: Error: selected processor does not support `ld1b z0.b,p1/z,[x8]'
> {standard input}:4006: Error: selected processor does not support `whilelo p4.s,wzr,w7'
>
> This is because inline assembly code explicitly resets cpu model to
> not have SVE support. Thus SVE instructions generated by compiler
> auto vectorization got rejected by assembler.
>
> Added SVE to the cpu model specified by inline assembly for SVE support.
> Not replacing the inline assembly with C atomics because the driver relies
> on specific LSE instruction to interface to co-processor [1].
>
> Fixes: 8a4f835971f5 ("common/octeontx2: add IO handling APIs")
> Cc: jerinj at marvell.com
> Cc: stable at dpdk.org

Reviewed-by: Jerin Jacob <jerinj at marvell.com>



>
> [1] https://mails.dpdk.org/archives/dev/2021-January/196092.html
>
> Signed-off-by: Ruifeng Wang <ruifeng.wang at arm.com>
> ---
> v3:
> Keep inline assembly and add sve extension to fix issue. (Pavan)
>
>  drivers/common/octeontx2/otx2_io_arm64.h | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/common/octeontx2/otx2_io_arm64.h b/drivers/common/octeontx2/otx2_io_arm64.h
> index b5c85d9a6..34268e3af 100644
> --- a/drivers/common/octeontx2/otx2_io_arm64.h
> +++ b/drivers/common/octeontx2/otx2_io_arm64.h
> @@ -21,6 +21,12 @@
>  #define otx2_prefetch_store_keep(ptr) ({\
>         asm volatile("prfm pstl1keep, [%x0]\n" : : "r" (ptr)); })
>
> +#if defined(__ARM_FEATURE_SVE)
> +#define __LSE_PREAMBLE " .cpu  generic+lse+sve\n"
> +#else
> +#define __LSE_PREAMBLE " .cpu  generic+lse\n"
> +#endif
> +
>  static __rte_always_inline uint64_t
>  otx2_atomic64_add_nosync(int64_t incr, int64_t *ptr)
>  {
> @@ -28,7 +34,7 @@ otx2_atomic64_add_nosync(int64_t incr, int64_t *ptr)
>
>         /* Atomic add with no ordering */
>         asm volatile (
> -               ".cpu  generic+lse\n"
> +               __LSE_PREAMBLE
>                 "ldadd %x[i], %x[r], [%[b]]"
>                 : [r] "=r" (result), "+m" (*ptr)
>                 : [i] "r" (incr), [b] "r" (ptr)
> @@ -43,7 +49,7 @@ otx2_atomic64_add_sync(int64_t incr, int64_t *ptr)
>
>         /* Atomic add with ordering */
>         asm volatile (
> -               ".cpu  generic+lse\n"
> +               __LSE_PREAMBLE
>                 "ldadda %x[i], %x[r], [%[b]]"
>                 : [r] "=r" (result), "+m" (*ptr)
>                 : [i] "r" (incr), [b] "r" (ptr)
> @@ -57,7 +63,7 @@ otx2_lmt_submit(rte_iova_t io_address)
>         uint64_t result;
>
>         asm volatile (
> -               ".cpu  generic+lse\n"
> +               __LSE_PREAMBLE
>                 "ldeor xzr,%x[rf],[%[rs]]" :
>                  [rf] "=r"(result): [rs] "r"(io_address));
>         return result;
> @@ -69,7 +75,7 @@ otx2_lmt_submit_release(rte_iova_t io_address)
>         uint64_t result;
>
>         asm volatile (
> -               ".cpu  generic+lse\n"
> +               __LSE_PREAMBLE
>                 "ldeorl xzr,%x[rf],[%[rs]]" :
>                  [rf] "=r"(result) : [rs] "r"(io_address));
>         return result;
> @@ -104,4 +110,5 @@ otx2_lmt_mov_seg(void *out, const void *in, const uint16_t segdw)
>                 dst128[i] = src128[i];
>  }
>
> +#undef __LSE_PREAMBLE
>  #endif /* _OTX2_IO_ARM64_H_ */
> --
> 2.25.1
>