RE: [PATCH v5 3/7] plugins: extend API to get latest memory value accessed

[Xingtao Yao (Fujitsu)]

Reviewed-by: Xingtao Yao <yaoxt.fnst@fujitsu.com>

> -----Original Message-----
> From: qemu-devel-bounces+yaoxt.fnst=fujitsu.com@nongnu.org
> <qemu-devel-bounces+yaoxt.fnst=fujitsu.com@nongnu.org> On Behalf Of
> Pierrick Bouvier
> Sent: Friday, July 5, 2024 8:34 AM
> To: qemu-devel@nongnu.org
> Cc: Alexandre Iooss <erdnaxe@crans.org>; Richard Henderson
> <richard.henderson@linaro.org>; Marcel Apfelbaum
> <marcel.apfelbaum@gmail.com>; Pierrick Bouvier <pierrick.bouvier@linaro.org>;
> Alex Bennée <alex.bennee@linaro.org>; Paolo Bonzini <pbonzini@redhat.com>;
> Yanan Wang <wangyanan55@huawei.com>; Mahmoud Mandour
> <ma.mandourr@gmail.com>; Eduardo Habkost <eduardo@habkost.net>; Philippe
> Mathieu-Daudé <philmd@linaro.org>
> Subject: [PATCH v5 3/7] plugins: extend API to get latest memory value 
> accessed
> 
> This value can be accessed only during a memory callback, using
> new qemu_plugin_mem_get_value function.
> 
> Returned value can be extended when QEMU will support accesses wider
> than 128 bits.
> 
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1719
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2152
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
> ---
>  include/qemu/qemu-plugin.h   | 32
> ++++++++++++++++++++++++++++++++
>  plugins/api.c                | 33
> +++++++++++++++++++++++++++++++++
>  plugins/qemu-plugins.symbols |  1 +
>  3 files changed, 66 insertions(+)
> 
> diff --git a/include/qemu/qemu-plugin.h b/include/qemu/qemu-plugin.h
> index c71c705b699..649ce89815f 100644
> --- a/include/qemu/qemu-plugin.h
> +++ b/include/qemu/qemu-plugin.h
> @@ -262,6 +262,29 @@ enum qemu_plugin_mem_rw {
>      QEMU_PLUGIN_MEM_RW,
>  };
> 
> +enum qemu_plugin_mem_value_type {
> +    QEMU_PLUGIN_MEM_VALUE_U8,
> +    QEMU_PLUGIN_MEM_VALUE_U16,
> +    QEMU_PLUGIN_MEM_VALUE_U32,
> +    QEMU_PLUGIN_MEM_VALUE_U64,
> +    QEMU_PLUGIN_MEM_VALUE_U128,
> +};
> +
> +/* typedef qemu_plugin_mem_value - value accessed during a load/store */
> +typedef struct {
> +    enum qemu_plugin_mem_value_type type;
> +    union {
> +        uint8_t u8;
> +        uint16_t u16;
> +        uint32_t u32;
> +        uint64_t u64;
> +        struct {
> +            uint64_t low;
> +            uint64_t high;
> +        } u128;
> +    } data;
> +} qemu_plugin_mem_value;
> +
>  /**
>   * enum qemu_plugin_cond - condition to enable callback
>   *
> @@ -551,6 +574,15 @@ bool
> qemu_plugin_mem_is_big_endian(qemu_plugin_meminfo_t info);
>  QEMU_PLUGIN_API
>  bool qemu_plugin_mem_is_store(qemu_plugin_meminfo_t info);
> 
> +/**
> + * qemu_plugin_mem_get_mem_value() - return last value loaded/stored
> + * @info: opaque memory transaction handle
> + *
> + * Returns: memory value
> + */
> +QEMU_PLUGIN_API
> +qemu_plugin_mem_value
> qemu_plugin_mem_get_value(qemu_plugin_meminfo_t info);
> +
>  /**
>   * qemu_plugin_get_hwaddr() - return handle for memory operation
>   * @info: opaque memory info structure
> diff --git a/plugins/api.c b/plugins/api.c
> index 2ff13d09de6..3316d4a04d4 100644
> --- a/plugins/api.c
> +++ b/plugins/api.c
> @@ -351,6 +351,39 @@ bool
> qemu_plugin_mem_is_store(qemu_plugin_meminfo_t info)
>      return get_plugin_meminfo_rw(info) & QEMU_PLUGIN_MEM_W;
>  }
> 
> +qemu_plugin_mem_value
> qemu_plugin_mem_get_value(qemu_plugin_meminfo_t info)
> +{
> +    uint64_t low = current_cpu->neg.plugin_mem_value_low;
> +    qemu_plugin_mem_value value;
> +
> +    switch (qemu_plugin_mem_size_shift(info)) {
> +    case 0:
> +        value.type = QEMU_PLUGIN_MEM_VALUE_U8;
> +        value.data.u8 = (uint8_t)low;
> +        break;
> +    case 1:
> +        value.type = QEMU_PLUGIN_MEM_VALUE_U16;
> +        value.data.u16 = (uint16_t)low;
> +        break;
> +    case 2:
> +        value.type = QEMU_PLUGIN_MEM_VALUE_U32;
> +        value.data.u32 = (uint32_t)low;
> +        break;
> +    case 3:
> +        value.type = QEMU_PLUGIN_MEM_VALUE_U64;
> +        value.data.u64 = low;
> +        break;
> +    case 4:
> +        value.type = QEMU_PLUGIN_MEM_VALUE_U128;
> +        value.data.u128.low = low;
> +        value.data.u128.high = current_cpu->neg.plugin_mem_value_high;
> +        break;
> +    default:
> +        g_assert_not_reached();
> +    }
> +    return value;
> +}
> +
>  /*
>   * Virtual Memory queries
>   */
> diff --git a/plugins/qemu-plugins.symbols b/plugins/qemu-plugins.symbols
> index ca773d8d9fe..eed9d8abd90 100644
> --- a/plugins/qemu-plugins.symbols
> +++ b/plugins/qemu-plugins.symbols
> @@ -13,6 +13,7 @@
>    qemu_plugin_insn_size;
>    qemu_plugin_insn_symbol;
>    qemu_plugin_insn_vaddr;
> +  qemu_plugin_mem_get_value;
>    qemu_plugin_mem_is_big_endian;
>    qemu_plugin_mem_is_sign_extended;
>    qemu_plugin_mem_is_store;
> --
> 2.39.2
>