Remove unnecessary fields in PciRomHeader. This allows a simplification to use `FromBytes` instead of reading fields piecemeal. A lot of these checks were redundant as well since it checks the size of the `data` first in `BiosImage`.
Reviewed-by: John Hubbard <[email protected]> Signed-off-by: Eliot Courtney <[email protected]> --- drivers/gpu/nova-core/vbios.rs | 68 ++++++++++-------------------------------- 1 file changed, 16 insertions(+), 52 deletions(-) diff --git a/drivers/gpu/nova-core/vbios.rs b/drivers/gpu/nova-core/vbios.rs index 52e33fdd4f5d..7399f2d087a9 100644 --- a/drivers/gpu/nova-core/vbios.rs +++ b/drivers/gpu/nova-core/vbios.rs @@ -533,67 +533,38 @@ fn from_id(image: &PciAtBiosImage, token_id: u8) -> Result<Self> { /// PCI ROM Expansion Header as defined in PCI Firmware Specification. /// -/// This is header is at the beginning of every image in the set of images in the ROM. It contains -/// a pointer to the PCI Data Structure which describes the image. For "NBSI" images (NoteBook -/// System Information), the ROM header deviates from the standard and contains an offset to the -/// NBSI image however we do not yet parse that in this module and keep it for future reference. +/// This header is at the beginning of every image in the set of images in the ROM. It contains a +/// pointer to the PCI Data Structure which describes the image. #[derive(Debug, Clone, Copy)] -#[expect(dead_code)] +#[repr(C)] struct PciRomHeader { /// 00h: Signature (0xAA55) signature: u16, - /// 02h: Reserved bytes for processor architecture unique data (20 bytes) - reserved: [u8; 20], - /// 16h: NBSI Data Offset (NBSI-specific, offset from header to NBSI image) - nbsi_data_offset: Option<u16>, + /// 02h: Reserved bytes for processor architecture unique data (22 bytes) + reserved: [u8; 22], /// 18h: Pointer to PCI Data Structure (offset from start of ROM image) pci_data_struct_offset: u16, - /// 1Ah: Size of block (this is NBSI-specific) - size_of_block: Option<u32>, } +// SAFETY: all bit patterns are valid for `PciRomHeader`. +unsafe impl FromBytes for PciRomHeader {} + impl PciRomHeader { fn new(dev: &device::Device, data: &[u8]) -> Result<Self> { - if data.len() < 26 { - // Need at least 26 bytes to read pciDataStrucPtr and sizeOfBlock. - return Err(EINVAL); - } - - let signature = u16::from_le_bytes([data[0], data[1]]); + let (rom_header, _) = PciRomHeader::from_bytes_copy_prefix(data) + .ok_or(EINVAL) + .inspect_err(|_| dev_err!(dev, "Not enough data for ROM header\n"))?; // Check for valid ROM signatures. - match signature { + match rom_header.signature { 0xAA55 | 0x4E56 => {} _ => { - dev_err!(dev, "ROM signature unknown {:#x}\n", signature); + dev_err!(dev, "ROM signature unknown {:#x}\n", rom_header.signature); return Err(EINVAL); } } - // Read the pointer to the PCI Data Structure at offset 0x18. - let pci_data_struct_ptr = u16::from_le_bytes([data[24], data[25]]); - - // Try to read optional fields if enough data. - let mut size_of_block = None; - let mut nbsi_data_offset = None; - - if data.len() >= 30 { - // Read size_of_block at offset 0x1A. - size_of_block = Some(u32::from_le_bytes([data[26], data[27], data[28], data[29]])); - } - - // For NBSI images, try to read the nbsiDataOffset at offset 0x16. - if data.len() >= 24 { - nbsi_data_offset = Some(u16::from_le_bytes([data[22], data[23]])); - } - - Ok(PciRomHeader { - signature, - reserved: [0u8; 20], - pci_data_struct_offset: pci_data_struct_ptr, - size_of_block, - nbsi_data_offset, - }) + Ok(rom_header) } } @@ -712,9 +683,9 @@ pub(crate) struct FwSecBiosImage { /// BIOS Image structure containing various headers and reference fields to all BIOS images. /// /// A BiosImage struct is embedded into all image types and implements common operations. -#[expect(dead_code)] struct BiosImage { /// PCI ROM Expansion Header + #[expect(dead_code)] rom_header: PciRomHeader, /// PCI Data Structure pcir: PcirStruct, @@ -759,15 +730,8 @@ fn is_last(&self) -> bool { /// Creates a new BiosImage from raw byte data. fn new(dev: &device::Device, data: &[u8]) -> Result<Self> { - // Ensure we have enough data for the ROM header. - if data.len() < 26 { - dev_err!(dev, "Not enough data for ROM header\n"); - return Err(EINVAL); - } - // Parse the ROM header. - let rom_header = PciRomHeader::new(dev, &data[0..26]) - .inspect_err(|e| dev_err!(dev, "Failed to create PciRomHeader: {:?}\n", e))?; + let rom_header = PciRomHeader::new(dev, data)?; // Get the PCI Data Structure using the pointer from the ROM header. let pcir_offset = usize::from(rom_header.pci_data_struct_offset); -- 2.54.0
