Re: [PATCH] [next] drm/amdgpu: Replace one-elements array with flex-array members

From: Alex Deucher
Date: Tue Nov 15 2022 - 09:29:38 EST


Applied. Thanks.

Alex

On Sun, Nov 13, 2022 at 2:44 AM Paulo Miguel Almeida
<paulo.miguel.almeida.rodenas@xxxxxxxxx> wrote:
>
> One-element arrays are deprecated, and we are replacing them with
> flexible array members instead. So, replace one-element array with
> flexible-array member in structs ATOM_I2C_VOLTAGE_OBJECT_V3,
> ATOM_ASIC_INTERNAL_SS_INFO_V2, ATOM_ASIC_INTERNAL_SS_INFO_V3,
> and refactor the rest of the code accordingly.
>
> Important to mention is that doing a build before/after this patch
> results in no functional binary output differences.
>
> This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
> routines on memcpy() and help us make progress towards globally
> enabling -fstrict-flex-arrays=3 [1].
>
> Link: https://github.com/KSPP/linux/issues/79
> Link: https://github.com/KSPP/linux/issues/238
> Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836 [1]
>
> Signed-off-by: Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@xxxxxxxxx>
> ---
> Binary difference findings:
>
> Some changes took more than a single line which changed the line
> number parameter passed to the drm_dbg function (which leverages
> kernel's dynamic debugging). Functionally-wise, nothing changed
> after doing a before/after patch build.
>
> ---
> .../gpu/drm/amd/display/dc/bios/bios_parser.c | 22 ++++++++++++-------
> drivers/gpu/drm/amd/include/atombios.h | 6 ++---
> 2 files changed, 17 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c b/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c
> index 6b9e64cd4379..a1a00f432168 100644
> --- a/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c
> +++ b/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c
> @@ -665,8 +665,9 @@ static enum bp_result get_ss_info_v3_1(
> if (!DATA_TABLES(ASIC_InternalSS_Info))
> return BP_RESULT_UNSUPPORTED;
>
> - ss_table_header_include = GET_IMAGE(ATOM_ASIC_INTERNAL_SS_INFO_V3,
> - DATA_TABLES(ASIC_InternalSS_Info));
> + ss_table_header_include = ((ATOM_ASIC_INTERNAL_SS_INFO_V3 *) bios_get_image(&bp->base,
> + DATA_TABLES(ASIC_InternalSS_Info),
> + struct_size(ss_table_header_include, asSpreadSpectrum, 1)));
> table_size =
> (le16_to_cpu(ss_table_header_include->sHeader.usStructureSize)
> - sizeof(ATOM_COMMON_TABLE_HEADER))
> @@ -1032,8 +1033,10 @@ static enum bp_result get_ss_info_from_internal_ss_info_tbl_V2_1(
> if (!DATA_TABLES(ASIC_InternalSS_Info))
> return result;
>
> - header = GET_IMAGE(ATOM_ASIC_INTERNAL_SS_INFO_V2,
> - DATA_TABLES(ASIC_InternalSS_Info));
> + header = ((ATOM_ASIC_INTERNAL_SS_INFO_V2 *) bios_get_image(
> + &bp->base,
> + DATA_TABLES(ASIC_InternalSS_Info),
> + struct_size(header, asSpreadSpectrum, 1)));
>
> memset(info, 0, sizeof(struct spread_spectrum_info));
>
> @@ -1712,8 +1715,10 @@ static uint32_t get_ss_entry_number_from_internal_ss_info_tbl_v2_1(
> if (!DATA_TABLES(ASIC_InternalSS_Info))
> return 0;
>
> - header_include = GET_IMAGE(ATOM_ASIC_INTERNAL_SS_INFO_V2,
> - DATA_TABLES(ASIC_InternalSS_Info));
> + header_include = ((ATOM_ASIC_INTERNAL_SS_INFO_V2 *) bios_get_image(
> + &bp->base,
> + DATA_TABLES(ASIC_InternalSS_Info),
> + struct_size(header_include, asSpreadSpectrum, 1)));
>
> size = (le16_to_cpu(header_include->sHeader.usStructureSize)
> - sizeof(ATOM_COMMON_TABLE_HEADER))
> @@ -1749,8 +1754,9 @@ static uint32_t get_ss_entry_number_from_internal_ss_info_tbl_V3_1(
> if (!DATA_TABLES(ASIC_InternalSS_Info))
> return number;
>
> - header_include = GET_IMAGE(ATOM_ASIC_INTERNAL_SS_INFO_V3,
> - DATA_TABLES(ASIC_InternalSS_Info));
> + header_include = ((ATOM_ASIC_INTERNAL_SS_INFO_V3 *) bios_get_image(&bp->base,
> + DATA_TABLES(ASIC_InternalSS_Info),
> + struct_size(header_include, asSpreadSpectrum, 1)));
> size = (le16_to_cpu(header_include->sHeader.usStructureSize) -
> sizeof(ATOM_COMMON_TABLE_HEADER)) /
> sizeof(ATOM_ASIC_SS_ASSIGNMENT_V3);
> diff --git a/drivers/gpu/drm/amd/include/atombios.h b/drivers/gpu/drm/amd/include/atombios.h
> index 60c44a8a067f..4dc738c51771 100644
> --- a/drivers/gpu/drm/amd/include/atombios.h
> +++ b/drivers/gpu/drm/amd/include/atombios.h
> @@ -5146,7 +5146,7 @@ typedef struct _ATOM_I2C_VOLTAGE_OBJECT_V3
> UCHAR ucVoltageControlOffset;
> UCHAR ucVoltageControlFlag; // Bit0: 0 - One byte data; 1 - Two byte data
> UCHAR ulReserved[3];
> - VOLTAGE_LUT_ENTRY asVolI2cLut[1]; // end with 0xff
> + VOLTAGE_LUT_ENTRY asVolI2cLut[]; // end with 0xff
> }ATOM_I2C_VOLTAGE_OBJECT_V3;
>
> // ATOM_I2C_VOLTAGE_OBJECT_V3.ucVoltageControlFlag
> @@ -6679,7 +6679,7 @@ typedef struct _ATOM_ASIC_INTERNAL_SS_INFO
> typedef struct _ATOM_ASIC_INTERNAL_SS_INFO_V2
> {
> ATOM_COMMON_TABLE_HEADER sHeader;
> - ATOM_ASIC_SS_ASSIGNMENT_V2 asSpreadSpectrum[1]; //this is point only.
> + ATOM_ASIC_SS_ASSIGNMENT_V2 asSpreadSpectrum[]; //this is point only.
> }ATOM_ASIC_INTERNAL_SS_INFO_V2;
>
> typedef struct _ATOM_ASIC_SS_ASSIGNMENT_V3
> @@ -6701,7 +6701,7 @@ typedef struct _ATOM_ASIC_SS_ASSIGNMENT_V3
> typedef struct _ATOM_ASIC_INTERNAL_SS_INFO_V3
> {
> ATOM_COMMON_TABLE_HEADER sHeader;
> - ATOM_ASIC_SS_ASSIGNMENT_V3 asSpreadSpectrum[1]; //this is pointer only.
> + ATOM_ASIC_SS_ASSIGNMENT_V3 asSpreadSpectrum[]; //this is pointer only.
> }ATOM_ASIC_INTERNAL_SS_INFO_V3;
>
>
> --
> 2.37.3
>