From 10718159890bc99cbcc7b5a38dade05df335e797 Mon Sep 17 00:00:00 2001 From: Calvin Owens Date: Thu, 12 Mar 2026 10:13:34 -0700 Subject: drm/amd/display: Fix uninitialized variable use which breaks full LTO Commit e1b385726f7f ("drm/amd/display: Add additional checks for PSP footer size") introduced a use of an uninitialized stack variable in dm_dmub_sw_init() (region_params.bss_data_size). Interestingly, this seems to cause no issue on normal kernels. But when full LTO is enabled, it causes the compiler to "optimize" out huge swaths of amdgpu initialization code, and the driver is unusable: amdgpu 0000:03:00.0: [drm] Loading DMUB firmware via PSP: version=0x07002F00 amdgpu 0000:03:00.0: sw_init of IP block failed 5 amdgpu 0000:03:00.0: amdgpu_device_ip_init failed amdgpu 0000:03:00.0: Fatal error during GPU init It surprises me that neither gcc nor clang emit a warning about this: I only found it by bisecting the LTO breakage. Fix by using the bss_data_size field from fw_meta_info_params, as was presumably intended. Fixes: e1b385726f7f ("drm/amd/display: Add additional checks for PSP footer size") Signed-off-by: Calvin Owens Reviewed-by: Harry Wentland Reviewed-by: Nathan Chancellor Signed-off-by: Alex Deucher (cherry picked from commit b7f1402f6ad24cc6b9a01fa09ebd1c6559d787d0) --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c index b3d6f2cd8ab6..0d1c772ef713 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -2554,7 +2554,7 @@ static int dm_dmub_sw_init(struct amdgpu_device *adev) fw_meta_info_params.fw_inst_const = adev->dm.dmub_fw->data + le32_to_cpu(hdr->header.ucode_array_offset_bytes) + PSP_HEADER_BYTES_256; - fw_meta_info_params.fw_bss_data = region_params.bss_data_size ? adev->dm.dmub_fw->data + + fw_meta_info_params.fw_bss_data = fw_meta_info_params.bss_data_size ? adev->dm.dmub_fw->data + le32_to_cpu(hdr->header.ucode_array_offset_bytes) + le32_to_cpu(hdr->inst_const_bytes) : NULL; fw_meta_info_params.custom_psp_footer_size = 0; -- cgit v1.2.3