On 5/18/26 7:55 PM, Eliot Courtney wrote: > 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`. > > Signed-off-by: Eliot Courtney <[email protected]> > --- > drivers/gpu/nova-core/vbios.rs | 68 > ++++++++++-------------------------------- > 1 file changed, 16 insertions(+), 52 deletions(-)
Reviewed-by: John Hubbard <[email protected]> thanks, -- John Hubbard > > diff --git a/drivers/gpu/nova-core/vbios.rs b/drivers/gpu/nova-core/vbios.rs > index 64d100b6699b..1dca7933fac5 100644 > --- a/drivers/gpu/nova-core/vbios.rs > +++ b/drivers/gpu/nova-core/vbios.rs > @@ -546,67 +546,38 @@ 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) > } > } > > @@ -722,11 +693,11 @@ 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 { > /// Used for logging. > dev: ARef<device::Device>, > /// PCI ROM Expansion Header > + #[expect(dead_code)] > rom_header: PciRomHeader, > /// PCI Data Structure > pcir: PcirStruct, > @@ -771,15 +742,8 @@ 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); >
