[dpdk-dev] [PATCH 13/28] eal/arm64: override I/O device read/write access for arm64

Jianbo Liu jianbo.liu at linaro.org
Fri Dec 16 11:12:13 CET 2016


On 15 December 2016 at 19:08, Jerin Jacob
<jerin.jacob at caviumnetworks.com> wrote:
> On Thu, Dec 15, 2016 at 06:17:32PM +0800, Jianbo Liu wrote:
>> On 15 December 2016 at 18:04, Jerin Jacob
>> <jerin.jacob at caviumnetworks.com> wrote:
>> > On Thu, Dec 15, 2016 at 05:53:05PM +0800, Jianbo Liu wrote:
>> >> On 14 December 2016 at 09:55, Jerin Jacob
>> >> <jerin.jacob at caviumnetworks.com> wrote:
>> >> > Override the generic I/O device memory read/write access and implement it
>> >> > using armv8 instructions for arm64.
>> >> >
>> >> > Signed-off-by: Jerin Jacob <jerin.jacob at caviumnetworks.com>
>> >> > ---
>> >> >  lib/librte_eal/common/include/arch/arm/rte_io.h    |   4 +
>> >> >  lib/librte_eal/common/include/arch/arm/rte_io_64.h | 183 +++++++++++++++++++++
>> >> >  2 files changed, 187 insertions(+)
>> >> >  create mode 100644 lib/librte_eal/common/include/arch/arm/rte_io_64.h
>> >> >
>> >> > diff --git a/lib/librte_eal/common/include/arch/arm/rte_io.h b/lib/librte_eal/common/include/arch/arm/rte_io.h
>> >> > index 74c1f2c..9593b42 100644
>> >> > --- a/lib/librte_eal/common/include/arch/arm/rte_io.h
>> >> > +++ b/lib/librte_eal/common/include/arch/arm/rte_io.h
>> >> > @@ -38,7 +38,11 @@
>> >> >  extern "C" {
>> >> >  #endif
>> >> >
>> >> > +#ifdef RTE_ARCH_64
>> >> > +#include "rte_io_64.h"
>> >> > +#else
>> >> >  #include "generic/rte_io.h"
>> >> > +#endif
>> >> >
>> >> >  #ifdef __cplusplus
>> >> >  }
>> >> > diff --git a/lib/librte_eal/common/include/arch/arm/rte_io_64.h b/lib/librte_eal/common/include/arch/arm/rte_io_64.h
>> >> > new file mode 100644
>> >> > index 0000000..09e7a89
>> >> > --- /dev/null
>> >> > +++ b/lib/librte_eal/common/include/arch/arm/rte_io_64.h
>> >> > @@ -0,0 +1,183 @@
>> >> > +/*
>> >> > + *   BSD LICENSE
>> >> > + *
>> >> > + *   Copyright (C) Cavium networks Ltd. 2016.
>> >> > + *
>> >> > + *   Redistribution and use in source and binary forms, with or without
>> >> > + *   modification, are permitted provided that the following conditions
>> >> > + *   are met:
>> >> > + *
>> >> > + *     * Redistributions of source code must retain the above copyright
>> >> > + *       notice, this list of conditions and the following disclaimer.
>> >> > + *     * Redistributions in binary form must reproduce the above copyright
>> >> > + *       notice, this list of conditions and the following disclaimer in
>> >> > + *       the documentation and/or other materials provided with the
>> >> > + *       distribution.
>> >> > + *     * Neither the name of Cavium networks nor the names of its
>> >> > + *       contributors may be used to endorse or promote products derived
>> >> > + *       from this software without specific prior written permission.
>> >> > + *
>> >> > + *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
>> >> > + *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
>> >> > + *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
>> >> > + *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
>> >> > + *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
>> >> > + *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
>> >> > + *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
>> >> > + *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
>> >> > + *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
>> >> > + *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
>> >> > + *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
>> >> > + */
>> >> > +
>> >> > +#ifndef _RTE_IO_ARM64_H_
>> >> > +#define _RTE_IO_ARM64_H_
>> >> > +
>> >> > +#ifdef __cplusplus
>> >> > +extern "C" {
>> >> > +#endif
>> >> > +
>> >> > +#include <stdint.h>
>> >> > +
>> >> > +#define RTE_OVERRIDE_IO_H
>> >> > +
>> >> > +#include "generic/rte_io.h"
>> >> > +#include "rte_atomic_64.h"
>> >> > +
>> >> > +static inline __attribute__((always_inline)) uint8_t
>> >> > +__rte_arm64_readb(const volatile void *addr)
>> >> > +{
>> >> > +       uint8_t val;
>> >> > +
>> >> > +       asm volatile(
>> >> > +                   "ldrb %w[val], [%x[addr]]"
>> >> > +                   : [val] "=r" (val)
>> >> > +                   : [addr] "r" (addr));
>> >> > +       return val;
>> >> > +}
>> >> > +
>> >> > +static inline __attribute__((always_inline)) uint16_t
>> >> > +__rte_arm64_readw(const volatile void *addr)
>> >> > +{
>> >> > +       uint16_t val;
>> >> > +
>> >> > +       asm volatile(
>> >> > +                   "ldrh %w[val], [%x[addr]]"
>> >> > +                   : [val] "=r" (val)
>> >> > +                   : [addr] "r" (addr));
>> >> > +       return val;
>> >> > +}
>> >> > +
>> >> > +static inline __attribute__((always_inline)) uint32_t
>> >> > +__rte_arm64_readl(const volatile void *addr)
>> >> > +{
>> >> > +       uint32_t val;
>> >> > +
>> >> > +       asm volatile(
>> >> > +                   "ldr %w[val], [%x[addr]]"
>> >> > +                   : [val] "=r" (val)
>> >> > +                   : [addr] "r" (addr));
>> >> > +       return val;
>> >> > +}
>> >> > +
>> >> > +static inline __attribute__((always_inline)) uint64_t
>> >> > +__rte_arm64_readq(const volatile void *addr)
>> >> > +{
>> >> > +       uint64_t val;
>> >> > +
>> >> > +       asm volatile(
>> >> > +                   "ldr %x[val], [%x[addr]]"
>> >> > +                   : [val] "=r" (val)
>> >> > +                   : [addr] "r" (addr));
>> >> > +       return val;
>> >> > +}
>> >> > +
>> >> > +static inline __attribute__((always_inline)) void
>> >> > +__rte_arm64_writeb(uint8_t val, volatile void *addr)
>> >> > +{
>> >> > +       asm volatile(
>> >> > +                   "strb %w[val], [%x[addr]]"
>> >> > +                   :
>> >> > +                   : [val] "r" (val), [addr] "r" (addr));
>> >> > +}
>> >> > +
>> >> > +static inline __attribute__((always_inline)) void
>> >> > +__rte_arm64_writew(uint16_t val, volatile void *addr)
>> >> > +{
>> >> > +       asm volatile(
>> >> > +                   "strh %w[val], [%x[addr]]"
>> >> > +                   :
>> >> > +                   : [val] "r" (val), [addr] "r" (addr));
>> >> > +}
>> >> > +
>> >> > +static inline __attribute__((always_inline)) void
>> >> > +__rte_arm64_writel(uint32_t val, volatile void *addr)
>> >> > +{
>> >> > +       asm volatile(
>> >> > +                   "str %w[val], [%x[addr]]"
>> >> > +                   :
>> >> > +                   : [val] "r" (val), [addr] "r" (addr));
>> >> > +}
>> >> > +
>> >> > +static inline __attribute__((always_inline)) void
>> >> > +__rte_arm64_writeq(uint64_t val, volatile void *addr)
>> >> > +{
>> >> > +       asm volatile(
>> >> > +                   "str %x[val], [%x[addr]]"
>> >> > +                   :
>> >> > +                   : [val] "r" (val), [addr] "r" (addr));
>> >> > +}
>> >>
>> >> I'm not quite sure about these overridings. Can you explain the
>> >> benefit to do so?
>> >
>> > Better to be native if there is option. That all. Do you see any issue?
>> > or what is the real concern?
>> >
>>
>> I think it's the same as the generic c version after compiling. Am I right?
>
> I really don't that is the case for all the scenarios like compiler may
> combine two 16bit reads one 32bit read etc and which will impact on IO

I wonder which compiler will do that as armv8 is 32/64 bit system?

> register access.
>
> But, I am sure the proposed scheme generates correct instruction in all the cases.


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