linux-kernel - Re: [PATCH] gpu: amd: replace open-coded offsetof() with builtin

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Date:   Mon, 27 Sep 2021 15:30:32 -0400
From:   Alex Deucher <alexdeucher@...il.com>
To:     Arnd Bergmann <arnd@...nel.org>
Cc:     Harry Wentland <harry.wentland@....com>,
        Leo Li <sunpeng.li@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        "Pan, Xinhui" <Xinhui.Pan@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, Evan Quan <evan.quan@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        amd-gfx list <amd-gfx@...ts.freedesktop.org>,
        Maling list - DRI developers 
        <dri-devel@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>, llvm@...ts.linux.dev
Subject: Re: [PATCH] gpu: amd: replace open-coded offsetof() with builtin

Applied.  Thanks!

Alex

On Mon, Sep 27, 2021 at 8:21 AM Arnd Bergmann <arnd@...nel.org> wrote:
>
> From: Arnd Bergmann <arnd@...db.de>
>
> The two AMD drivers have their own custom offsetof() implementation
> that now triggers a warning with recent versions of clang:
>
> drivers/gpu/drm/radeon/radeon_atombios.c:133:14: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]
>
> Change all the instances to use the normal offsetof() provided
> by the kernel that does not have this problem.
>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  drivers/gpu/drm/amd/display/dc/bios/command_table2.c  | 4 +---
>  drivers/gpu/drm/amd/include/atombios.h                | 2 +-
>  drivers/gpu/drm/amd/pm/powerplay/hwmgr/ppatomfwctrl.h | 4 ++--
>  drivers/gpu/drm/radeon/atombios.h                     | 2 +-
>  4 files changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/bios/command_table2.c b/drivers/gpu/drm/amd/display/dc/bios/command_table2.c
> index f1f672a997d7..4f37be727332 100644
> --- a/drivers/gpu/drm/amd/display/dc/bios/command_table2.c
> +++ b/drivers/gpu/drm/amd/display/dc/bios/command_table2.c
> @@ -44,9 +44,7 @@
>         bp->base.ctx->logger
>
>  #define GET_INDEX_INTO_MASTER_TABLE(MasterOrData, FieldName)\
> -       (((char *)(&((\
> -               struct atom_master_list_of_##MasterOrData##_functions_v2_1 *)0)\
> -               ->FieldName)-(char *)0)/sizeof(uint16_t))
> +       (offsetof(struct atom_master_list_of_##MasterOrData##_functions_v2_1, FieldName) / sizeof(uint16_t))
>
>  #define EXEC_BIOS_CMD_TABLE(fname, params)\
>         (amdgpu_atom_execute_table(((struct amdgpu_device *)bp->base.ctx->driver_context)->mode_info.atom_context, \
> diff --git a/drivers/gpu/drm/amd/include/atombios.h b/drivers/gpu/drm/amd/include/atombios.h
> index 6a505d1b82a5..da895d1f3b4f 100644
> --- a/drivers/gpu/drm/amd/include/atombios.h
> +++ b/drivers/gpu/drm/amd/include/atombios.h
> @@ -7148,7 +7148,7 @@ typedef struct _ATOM_ASIC_INTERNAL_SS_INFO_V3
>  #define GET_COMMAND_TABLE_COMMANDSET_REVISION(TABLE_HEADER_OFFSET) (((static_cast<ATOM_COMMON_TABLE_HEADER*>(TABLE_HEADER_OFFSET))->ucTableFormatRevision )&0x3F)
>  #define GET_COMMAND_TABLE_PARAMETER_REVISION(TABLE_HEADER_OFFSET)  (((static_cast<ATOM_COMMON_TABLE_HEADER*>(TABLE_HEADER_OFFSET))->ucTableContentRevision)&0x3F)
>  #else // not __cplusplus
> -#define   GetIndexIntoMasterTable(MasterOrData, FieldName) (((char*)(&((ATOM_MASTER_LIST_OF_##MasterOrData##_TABLES*)0)->FieldName)-(char*)0)/sizeof(USHORT))
> +#define   GetIndexIntoMasterTable(MasterOrData, FieldName) (offsetof(ATOM_MASTER_LIST_OF_##MasterOrData##_TABLES, FieldName) / sizeof(USHORT))
>
>  #define GET_COMMAND_TABLE_COMMANDSET_REVISION(TABLE_HEADER_OFFSET) ((((ATOM_COMMON_TABLE_HEADER*)TABLE_HEADER_OFFSET)->ucTableFormatRevision)&0x3F)
>  #define GET_COMMAND_TABLE_PARAMETER_REVISION(TABLE_HEADER_OFFSET)  ((((ATOM_COMMON_TABLE_HEADER*)TABLE_HEADER_OFFSET)->ucTableContentRevision)&0x3F)
> diff --git a/drivers/gpu/drm/amd/pm/powerplay/hwmgr/ppatomfwctrl.h b/drivers/gpu/drm/amd/pm/powerplay/hwmgr/ppatomfwctrl.h
> index b7e2651b570b..2fc1733bcdcf 100644
> --- a/drivers/gpu/drm/amd/pm/powerplay/hwmgr/ppatomfwctrl.h
> +++ b/drivers/gpu/drm/amd/pm/powerplay/hwmgr/ppatomfwctrl.h
> @@ -29,9 +29,9 @@
>  typedef enum atom_smu9_syspll0_clock_id BIOS_CLKID;
>
>  #define GetIndexIntoMasterCmdTable(FieldName) \
> -       (((char*)(&((struct atom_master_list_of_command_functions_v2_1*)0)->FieldName)-(char*)0)/sizeof(uint16_t))
> +       (offsetof(struct atom_master_list_of_command_functions_v2_1, FieldName) / sizeof(uint16_t))
>  #define GetIndexIntoMasterDataTable(FieldName) \
> -       (((char*)(&((struct atom_master_list_of_data_tables_v2_1*)0)->FieldName)-(char*)0)/sizeof(uint16_t))
> +       (offsetof(struct atom_master_list_of_data_tables_v2_1, FieldName) / sizeof(uint16_t))
>
>  #define PP_ATOMFWCTRL_MAX_VOLTAGE_ENTRIES 32
>
> diff --git a/drivers/gpu/drm/radeon/atombios.h b/drivers/gpu/drm/radeon/atombios.h
> index 83e8b8547f9b..bd5dc09e860f 100644
> --- a/drivers/gpu/drm/radeon/atombios.h
> +++ b/drivers/gpu/drm/radeon/atombios.h
> @@ -5983,7 +5983,7 @@ typedef struct _ATOM_ASIC_INTERNAL_SS_INFO_V3
>  #define GET_COMMAND_TABLE_COMMANDSET_REVISION(TABLE_HEADER_OFFSET) (((static_cast<ATOM_COMMON_TABLE_HEADER*>(TABLE_HEADER_OFFSET))->ucTableFormatRevision )&0x3F)
>  #define GET_COMMAND_TABLE_PARAMETER_REVISION(TABLE_HEADER_OFFSET)  (((static_cast<ATOM_COMMON_TABLE_HEADER*>(TABLE_HEADER_OFFSET))->ucTableContentRevision)&0x3F)
>  #else // not __cplusplus
> -#define        GetIndexIntoMasterTable(MasterOrData, FieldName) (((char*)(&((ATOM_MASTER_LIST_OF_##MasterOrData##_TABLES*)0)->FieldName)-(char*)0)/sizeof(USHORT))
> +#define        GetIndexIntoMasterTable(MasterOrData, FieldName) (offsetof(ATOM_MASTER_LIST_OF_##MasterOrData##_TABLES, FieldName)/sizeof(USHORT))
>
>  #define GET_COMMAND_TABLE_COMMANDSET_REVISION(TABLE_HEADER_OFFSET) ((((ATOM_COMMON_TABLE_HEADER*)TABLE_HEADER_OFFSET)->ucTableFormatRevision)&0x3F)
>  #define GET_COMMAND_TABLE_PARAMETER_REVISION(TABLE_HEADER_OFFSET)  ((((ATOM_COMMON_TABLE_HEADER*)TABLE_HEADER_OFFSET)->ucTableContentRevision)&0x3F)
> --
> 2.29.2
>