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devices: pci: ignore writable_bits when adding caps

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The add_capability() function was using the normal PCI configuration
write_byte() function, which enforces read-only regions.  This won't
work once the appropriate regions of config space are marked as read
only in the following commit, so add an internal-only helper function to
access bytes without applying writable_bits.

Change-Id: If61f79cd80950bf517d69c18aaf98c2e76841a56
Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1240658
Reviewed-by: Dylan Reid <dgreid@chromium.org>
This commit is contained in:
Daniel Verkamp 2018-09-24 10:45:47 -07:00 committed by chrome-bot
parent 9f2bbc8a91
commit b2d6ffac5e
1 changed files with 14 additions and 5 deletions
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19
devices/src/pci/pci_configuration.rs
View file

@ -244,11 +244,20 @@ impl PciConfiguration {
/// Writes a byte to `offset`.
pub fn write_byte(&mut self, offset: usize, value: u8) {
self.write_byte_internal(offset, value, true);
}
/// Writes a byte to `offset`, optionally enforcing read-only bits.
fn write_byte_internal(&mut self, offset: usize, value: u8, apply_writable_mask: bool) {
let shift = (offset % 4) * 8;
let reg_idx = offset / 4;
if let Some(r) = self.registers.get_mut(reg_idx) {
let writable_mask = self.writable_bits[reg_idx];
let writable_mask = if apply_writable_mask {
self.writable_bits[reg_idx]
} else {
0xffff_ffff
};
let mask = (0xffu32 << shift) & writable_mask;
let shifted_value = (u32::from(value) << shift) & writable_mask;
*r = *r & !mask | shifted_value;
@ -330,11 +339,11 @@ impl PciConfiguration {
return None;
}
self.registers[STATUS_REG] |= STATUS_REG_CAPABILITIES_USED_MASK;
self.write_byte(tail_offset, cap_offset as u8);
self.write_byte(cap_offset, cap_data.id() as u8);
self.write_byte(cap_offset + 1, 0); // Next pointer.
self.write_byte_internal(tail_offset, cap_offset as u8, false);
self.write_byte_internal(cap_offset, cap_data.id() as u8, false);
self.write_byte_internal(cap_offset + 1, 0, false); // Next pointer.
for (i, byte) in cap_data.bytes().iter().enumerate() {
self.write_byte(cap_offset + i + 2, *byte);
self.write_byte_internal(cap_offset + i + 2, *byte, false);
}
self.last_capability = Some((cap_offset, total_len));
Some(cap_offset)