Re: [PATCH v2 05/15] fuzz: Declare DMA Read callback function

[Darren Kenny <darren.kenny@oracle.com>]

On Wednesday, 2020-08-19 at 02:11:00 -04, Alexander Bulekov wrote:
> This patch declares the fuzz_dma_read_cb function and uses the
> preprocessor and linker(weak symbols) to handle these cases:
>
> When we build softmmu/all with --enable-fuzzing, there should be no
> strong symbol defined for fuzz_dma_read_cb, and we link against a weak
> stub function.
>
> When we build softmmu/fuzz with --enable-fuzzing, we link agains the

TYPO: s/agains/against/

> strong symbol in general_fuzz.c
>
> When we build softmmu/all without --enable-fuzzing, fuzz_dma_read_cb is
> an empty, inlined function. As long as we don't call any other functions
> when building the arguments, there should be no overhead.
>
> Signed-off-by: Alexander Bulekov <alxndr@bu.edu>

Reviewed-by: Darren Kenny <darren.kenny@oracle.com>

> ---
>  include/exec/memory.h | 15 +++++++++++++++
>  softmmu/memory.c      | 13 +++++++++++++
>  2 files changed, 28 insertions(+)
>
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index 307e527835..2ec3b597f1 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -47,6 +47,21 @@
>          OBJECT_GET_CLASS(IOMMUMemoryRegionClass, (obj), \
>                           TYPE_IOMMU_MEMORY_REGION)
>  
> +#ifdef CONFIG_FUZZ
> +void fuzz_dma_read_cb(size_t addr,
> +                      size_t len,
> +                      MemoryRegion *mr,
> +                      bool is_write);
> +#else
> +static inline void fuzz_dma_read_cb(size_t addr,
> +                                    size_t len,
> +                                    MemoryRegion *mr,
> +                                    bool is_write)
> +{
> +    /* Do Nothing */
> +}
> +#endif
> +
>  extern bool global_dirty_log;
>  
>  typedef struct MemoryRegionOps MemoryRegionOps;
> diff --git a/softmmu/memory.c b/softmmu/memory.c
> index af25987518..b0c2cf2535 100644
> --- a/softmmu/memory.c
> +++ b/softmmu/memory.c
> @@ -3223,6 +3223,19 @@ void memory_region_init_rom_device(MemoryRegion *mr,
>      vmstate_register_ram(mr, owner_dev);
>  }
>  
> +/*
> + * Support softmmu builds with CONFIG_FUZZ using a weak symbol and a stub for
> + * the fuzz_dma_read_cb callback
> + */
> +#ifdef CONFIG_FUZZ
> +void __attribute__((weak)) fuzz_dma_read_cb(size_t addr,
> +                      size_t len,
> +                      MemoryRegion *mr,
> +                      bool is_write)
> +{
> +}
> +#endif
> +
>  static const TypeInfo memory_region_info = {
>      .parent             = TYPE_OBJECT,
>      .name               = TYPE_MEMORY_REGION,
> -- 
> 2.27.0