Re: [FFmpeg-devel] [PATCH 1/2] lavc/startcode: add R-V Zbb startcode_find_candidate

["Rémi Denis-Courmont" <remi@remlab.net>]

Le sunnuntaina 12. toukokuuta 2024, 13.55.13 EEST Rémi Denis-Courmont a écrit 
:
> ---
>  libavcodec/h264dsp.c             |  2 +
>  libavcodec/h264dsp.h             |  2 +
>  libavcodec/riscv/Makefile        |  2 +
>  libavcodec/riscv/h264dsp_init.c  | 40 ++++++++++++++++
>  libavcodec/riscv/startcode_rvb.S | 81 ++++++++++++++++++++++++++++++++
>  libavcodec/riscv/vc1dsp_init.c   |  7 ++-
>  6 files changed, 133 insertions(+), 1 deletion(-)
>  create mode 100644 libavcodec/riscv/h264dsp_init.c
>  create mode 100644 libavcodec/riscv/startcode_rvb.S
> 
> diff --git a/libavcodec/h264dsp.c b/libavcodec/h264dsp.c
> index 4d2ee10bab..1ba936be1c 100644
> --- a/libavcodec/h264dsp.c
> +++ b/libavcodec/h264dsp.c
> @@ -158,6 +158,8 @@ av_cold void ff_h264dsp_init(H264DSPContext *c, const
> int bit_depth, ff_h264dsp_init_arm(c, bit_depth, chroma_format_idc);
>  #elif ARCH_PPC
>      ff_h264dsp_init_ppc(c, bit_depth, chroma_format_idc);
> +#elif ARCH_RISCV
> +    ff_h264dsp_init_riscv(c, bit_depth, chroma_format_idc);
>  #elif ARCH_X86
>      ff_h264dsp_init_x86(c, bit_depth, chroma_format_idc);
>  #elif ARCH_MIPS
> diff --git a/libavcodec/h264dsp.h b/libavcodec/h264dsp.h
> index e0880c4d88..4a9cb1568d 100644
> --- a/libavcodec/h264dsp.h
> +++ b/libavcodec/h264dsp.h
> @@ -125,6 +125,8 @@ void ff_h264dsp_init_arm(H264DSPContext *c, const int
> bit_depth, const int chroma_format_idc);
>  void ff_h264dsp_init_ppc(H264DSPContext *c, const int bit_depth,
>                           const int chroma_format_idc);
> +void ff_h264dsp_init_riscv(H264DSPContext *c, const int bit_depth,
> +                           const int chroma_format_idc);
>  void ff_h264dsp_init_x86(H264DSPContext *c, const int bit_depth,
>                           const int chroma_format_idc);
>  void ff_h264dsp_init_mips(H264DSPContext *c, const int bit_depth,
> diff --git a/libavcodec/riscv/Makefile b/libavcodec/riscv/Makefile
> index f2348e259e..319ea6427b 100644
> --- a/libavcodec/riscv/Makefile
> +++ b/libavcodec/riscv/Makefile
> @@ -28,6 +28,7 @@ OBJS-$(CONFIG_JPEG2000_DECODER) +=
> riscv/jpeg2000dsp_init.o RVV-OBJS-$(CONFIG_JPEG2000_DECODER) +=
> riscv/jpeg2000dsp_rvv.o
>  OBJS-$(CONFIG_H264CHROMA) += riscv/h264_chroma_init_riscv.o
>  RVV-OBJS-$(CONFIG_H264CHROMA) += riscv/h264_mc_chroma.o
> +OBJS-$(CONFIG_H264DSP) += riscv/h264dsp_init.o
>  OBJS-$(CONFIG_HUFFYUV_DECODER) += riscv/huffyuvdsp_init.o
>  RVV-OBJS-$(CONFIG_HUFFYUV_DECODER) += riscv/huffyuvdsp_rvv.o
>  OBJS-$(CONFIG_IDCTDSP) += riscv/idctdsp_init.o
> @@ -51,6 +52,7 @@ OBJS-$(CONFIG_RV34DSP) += riscv/rv34dsp_init.o
>  RVV-OBJS-$(CONFIG_RV34DSP) += riscv/rv34dsp_rvv.o
>  OBJS-$(CONFIG_RV40_DECODER) += riscv/rv40dsp_init.o
>  RVV-OBJS-$(CONFIG_RV40_DECODER) += riscv/rv40dsp_rvv.o
> +RV-OBJS-$(CONFIG_STARTCODE) += riscv/startcode_rvb.o
>  OBJS-$(CONFIG_SVQ1_ENCODER) += riscv/svqenc_init.o
>  RVV-OBJS-$(CONFIG_SVQ1_ENCODER) += riscv/svqenc_rvv.o
>  OBJS-$(CONFIG_TAK_DECODER) += riscv/takdsp_init.o
> diff --git a/libavcodec/riscv/h264dsp_init.c
> b/libavcodec/riscv/h264dsp_init.c new file mode 100644
> index 0000000000..60c84734cd
> --- /dev/null
> +++ b/libavcodec/riscv/h264dsp_init.c
> @@ -0,0 +1,40 @@
> +/*
> + * Copyright © 2024 Rémi Denis-Courmont.
> + *
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with FFmpeg; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
> USA + */
> +
> +#include "config.h"
> +
> +#include <stdint.h>
> +
> +#include "libavutil/attributes.h"
> +#include "libavutil/cpu.h"
> +#include "libavcodec/h264dsp.h"
> +
> +extern int ff_startcode_find_candidate_rvb(const uint8_t *, int);
> +
> +av_cold void ff_h264dsp_init_riscv(H264DSPContext *dsp, const int
> bit_depth, +                                   const int chroma_format_idc)
> +{
> +#if HAVE_RV
> +    int flags = av_get_cpu_flags();
> +
> +    if (flags & AV_CPU_FLAG_RVB_BASIC)
> +        dsp->startcode_find_candidate = ff_startcode_find_candidate_rvb;
> +#endif
> +}
> diff --git a/libavcodec/riscv/startcode_rvb.S
> b/libavcodec/riscv/startcode_rvb.S new file mode 100644
> index 0000000000..25b888a8dd
> --- /dev/null
> +++ b/libavcodec/riscv/startcode_rvb.S
> @@ -0,0 +1,81 @@
> +/*
> + * Copyright © 2024 Rémi Denis-Courmont.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met: + *
> + * 1. Redistributions of source code must retain the above copyright
> notice, + *    this list of conditions and the following disclaimer.
> + *
> + * 2. 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.
> + *
> + * 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.
> + */
> +
> +#include "libavutil/riscv/asm.S"
> +
> +        .macro  lx rd, addr
> +#if (__riscv_xlen == 32)
> +        lw      \rd, \addr
> +#elif (__riscv_xlen == 64)
> +        ld      \rd, \addr
> +#else
> +        lq      \rd, \addr
> +#endif
> +        .endm
> +
> +func ff_startcode_find_candidate_rvb, zbb
> +        add     a1, a0, a1
> +
> +        // Potentially unaligned head
> +        andi    t0, a0, -(__riscv_xlen / 8)
> +        beq     a0, a1, 2f
> +
> +        andi    t1, a0, (__riscv_xlen / 8) - 1
> +        lx      t2, (t0)
> +        li      t3, __riscv_xlen
> +        slli    t1, t1, 3
> +        orc.b   t2, t2
> +        sub     t3, t3, t1
> +        not     t2, t2
> +        srl     t2, t2, t1
> +        sll     t2, t2, t1
> +        bnez    t2, 4f
> +
> +        // Main loop (including potentially short tail)
> +        ble     a1, t0, 2f
> +        li      t3, -1
> +1:
> +        lx      t2, (__riscv_xlen / 8)(t0)
> +        addi    t0, t0, __riscv_xlen / 8
> +        orc.b   t2, t2
> +        bne     t2, t3, 3f // t2 != -1 iff (at least one) zero byte
> +        bgt     a1, t0, 1b

Incorrect boundary check, so this could lead to OOB read. Ditto above.

-- 
Rémi Denis-Courmont
http://www.remlab.net/



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