drm/amd/pm: And destination bounds checking to struct copy

In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memcpy(), memmove(), and memset(), avoid
intentionally writing across neighboring fields.

The "Board Parameters" members of the structs:
	struct atom_smc_dpm_info_v4_5
	struct atom_smc_dpm_info_v4_6
	struct atom_smc_dpm_info_v4_7
	struct atom_smc_dpm_info_v4_10
are written to the corresponding members of the corresponding PPTable_t
variables, but they lack destination size bounds checking, which means
the compiler cannot verify at compile time that this is an intended and
safe memcpy().

Since the header files are effectively immutable[1] and a struct_group()
cannot be used, nor a common struct referenced by both sides of the
memcpy() arguments, add a new helper, amdgpu_memcpy_trailing(), to
perform the bounds checking at compile time. Replace the open-coded
memcpy()s with amdgpu_memcpy_trailing() which includes enough context
for the bounds checking.

"objdump -d" shows no object code changes.

[1] https://lore.kernel.org/lkml/e56aad3c-a06f-da07-f491-a894a570d78f@amd.com

Cc: "Christian König" <christian.koenig@amd.com>
Cc: "Pan, Xinhui" <Xinhui.Pan@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Hawking Zhang <Hawking.Zhang@amd.com>
Cc: Feifei Xu <Feifei.Xu@amd.com>
Cc: Likun Gao <Likun.Gao@amd.com>
Cc: Jiawei Gu <Jiawei.Gu@amd.com>
Cc: Evan Quan <evan.quan@amd.com>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/pm/inc/amdgpu_smu.h

@@ -1335,6 +1335,30 @@ enum smu_cmn2asic_mapping_type {
 #define WORKLOAD_MAP(profile, workload) \
 	[profile] = {1, (workload)}
 
+/**
+ * smu_memcpy_trailing - Copy the end of one structure into the middle of another
+ *
+ * @dst: Pointer to destination struct
+ * @first_dst_member: The member name in @dst where the overwrite begins
+ * @last_dst_member: The member name in @dst where the overwrite ends after
+ * @src: Pointer to the source struct
+ * @first_src_member: The member name in @src where the copy begins
+ *
+ */
+#define smu_memcpy_trailing(dst, first_dst_member, last_dst_member,	   \
+			    src, first_src_member)			   \
+({									   \
+	size_t __src_offset = offsetof(typeof(*(src)), first_src_member);  \
+	size_t __src_size = sizeof(*(src)) - __src_offset;		   \
+	size_t __dst_offset = offsetof(typeof(*(dst)), first_dst_member);  \
+	size_t __dst_size = offsetofend(typeof(*(dst)), last_dst_member) - \
+			    __dst_offset;				   \
+	BUILD_BUG_ON(__src_size != __dst_size);				   \
+	__builtin_memcpy((u8 *)(dst) + __dst_offset,			   \
+			 (u8 *)(src) + __src_offset,			   \
+			 __dst_size);					   \
+})
+
 #if !defined(SWSMU_CODE_LAYER_L2) && !defined(SWSMU_CODE_LAYER_L3) && !defined(SWSMU_CODE_LAYER_L4)
 int smu_get_power_limit(void *handle,
 			uint32_t *limit,

drivers/gpu/drm/amd/pm/swsmu/smu11/arcturus_ppt.c

@@ -483,10 +483,8 @@ static int arcturus_append_powerplay_table(struct smu_context *smu)
 
 	if ((smc_dpm_table->table_header.format_revision == 4) &&
 	    (smc_dpm_table->table_header.content_revision == 6))
-		memcpy(&smc_pptable->MaxVoltageStepGfx,
-		       &smc_dpm_table->maxvoltagestepgfx,
-		       sizeof(*smc_dpm_table) - offsetof(struct atom_smc_dpm_info_v4_6, maxvoltagestepgfx));
-
+		smu_memcpy_trailing(smc_pptable, MaxVoltageStepGfx, BoardReserved,
+				    smc_dpm_table, maxvoltagestepgfx);
 	return 0;
 }
 

drivers/gpu/drm/amd/pm/swsmu/smu11/navi10_ppt.c

@@ -431,16 +431,16 @@ static int navi10_append_powerplay_table(struct smu_context *smu)
 
 	switch (smc_dpm_table->table_header.content_revision) {
 	case 5: /* nv10 and nv14 */
-		memcpy(smc_pptable->I2cControllers, smc_dpm_table->I2cControllers,
-			sizeof(*smc_dpm_table) - sizeof(smc_dpm_table->table_header));
+		smu_memcpy_trailing(smc_pptable, I2cControllers, BoardReserved,
+				    smc_dpm_table, I2cControllers);
 		break;
 	case 7: /* nv12 */
 		ret = amdgpu_atombios_get_data_table(adev, index, NULL, NULL, NULL,
 					      (uint8_t **)&smc_dpm_table_v4_7);
 		if (ret)
 			return ret;
-		memcpy(smc_pptable->I2cControllers, smc_dpm_table_v4_7->I2cControllers,
-			sizeof(*smc_dpm_table_v4_7) - sizeof(smc_dpm_table_v4_7->table_header));
+		smu_memcpy_trailing(smc_pptable, I2cControllers, BoardReserved,
+				    smc_dpm_table_v4_7, I2cControllers);
 		break;
 	default:
 		dev_err(smu->adev->dev, "smc_dpm_info with unsupported content revision %d!\n",

drivers/gpu/drm/amd/pm/swsmu/smu13/aldebaran_ppt.c

@@ -409,9 +409,8 @@ static int aldebaran_append_powerplay_table(struct smu_context *smu)
 
 	if ((smc_dpm_table->table_header.format_revision == 4) &&
 	    (smc_dpm_table->table_header.content_revision == 10))
-		memcpy(&smc_pptable->GfxMaxCurrent,
-		       &smc_dpm_table->GfxMaxCurrent,
-		       sizeof(*smc_dpm_table) - offsetof(struct atom_smc_dpm_info_v4_10, GfxMaxCurrent));
+		smu_memcpy_trailing(smc_pptable, GfxMaxCurrent, reserved,
+				    smc_dpm_table, GfxMaxCurrent);
 	return 0;
 }