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Date:   Sun, 13 Nov 2022 20:44:05 +1300
From:   Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@gmail.com>
To:     Harry Wentland <harry.wentland@amd.com>,
        Leo Li <sunpeng.li@amd.com>,
        Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        Christian =?utf-8?B?S8O2bmln?= <christian.koenig@amd.com>,
        "Pan, Xinhui" <Xinhui.Pan@amd.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@gmail.com>,
        Slark Xiao <slark_xiao@163.com>,
        Rongguang Wei <weirongguang@kylinos.cn>,
        amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Cc:     linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org,
        paulo.miguel.almeida.rodenas@gmail.com
Subject: [PATCH] [next] drm/amdgpu: Replace one-elements array with
 flex-array members
Message-ID: <Y3CgReK3e519a7bs@mail.google.com>
MIME-Version: 1.0
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Precedence: bulk

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@gmail.com>
---
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