[PATCH v2 2/3] rust: bitfield: Add KUNIT tests for bitfield

Alexandre Courbot
2026-04-09T14:59:16Z

From: Joel Fernandes <joelagnelf@nvidia.com>

Add KUNIT tests to make sure the macro is working correctly.

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
[acourbot: update code to latest bitfield! macro.]
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
---
rust/kernel/bitfield.rs | 318 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 318 insertions(+)

diff --git a/rust/kernel/bitfield.rs b/rust/kernel/bitfield.rs
index f5948eec8a76..9ab8dafff36c 100644
--- a/rust/kernel/bitfield.rs
+++ b/rust/kernel/bitfield.rs
@@ -489,3 +489,321 @@ fn fmt(&self, f: &mut ::kernel::fmt::Formatter<'_>) -> ::kernel::fmt::Result {
}
};
}
+
+#[::kernel::macros::kunit_tests(kernel_bitfield)]
+mod tests {
+ use core::convert::TryFrom;
+
+ use pin_init::Zeroable;
+
+ use kernel::num::Bounded;
+
+ // Enum types for testing => and ?=> conversions
+ #[derive(Debug, Clone, Copy, PartialEq)]
+ enum MemoryType {
+ Unmapped = 0,
+ Normal = 1,
+ Device = 2,
+ Reserved = 3,
+ }
+
+ impl TryFrom<Bounded<u64, 4>> for MemoryType {
+ type Error = u64;
+ fn try_from(value: Bounded<u64, 4>) -> Result<Self, Self::Error> {
+ match value.get() {
+ 0 => Ok(MemoryType::Unmapped),
+ 1 => Ok(MemoryType::Normal),
+ 2 => Ok(MemoryType::Device),
+ 3 => Ok(MemoryType::Reserved),
+ _ => Err(value.get()),
+ }
+ }
+ }
+
+ impl From<MemoryType> for Bounded<u64, 4> {
+ fn from(mt: MemoryType) -> Bounded<u64, 4> {
+ Bounded::from_expr(mt as u64)
+ }
+ }
+
+ #[derive(Debug, Clone, Copy, PartialEq)]
+ enum Priority {
+ Low = 0,
+ Medium = 1,
+ High = 2,
+ Critical = 3,
+ }
+
+ impl From<Bounded<u16, 2>> for Priority {
+ fn from(value: Bounded<u16, 2>) -> Self {
+ match value & 0x3 {
+ 0 => Priority::Low,
+ 1 => Priority::Medium,
+ 2 => Priority::High,
+ _ => Priority::Critical,
+ }
+ }
+ }
+
+ impl From<Priority> for Bounded<u16, 2> {
+ fn from(p: Priority) -> Bounded<u16, 2> {
+ Bounded::from_expr(p as u16)
+ }
+ }
+
+ bitfield! {
+ struct TestPageTableEntry(u64) {
+ 0:0 present;
+ 1:1 writable;
+ 11:9 available;
+ 15:12 mem_type ?=> MemoryType;
+ 51:16 pfn;
+ 61:52 available2;
+ }
+ }
+
+ bitfield! {
+ struct TestControlRegister(u16) {
+ 0:0 enable;
+ 3:1 mode;
+ 5:4 priority => Priority;
+ 7:4 priority_nibble;
+ 15:8 channel;
+ }
+ }
+
+ bitfield! {
+ struct TestStatusRegister(u8) {
+ 0:0 ready;
+ 1:1 error;
+ 3:2 state;
+ 7:4 reserved;
+ 7:0 full_byte; // For entire register
+ }
+ }
+
+ #[test]
+ fn test_single_bits() {
+ let mut pte = TestPageTableEntry::zeroed();
+
+ assert!(!pte.present().into_bool());
+ assert!(!pte.writable().into_bool());
+ assert_eq!(u64::from(pte), 0x0);
+
+ pte = pte.with_present(true);
+ assert!(pte.present().into_bool());
+ assert_eq!(u64::from(pte), 0x1);
+
+ pte = pte.with_writable(true);
+ assert!(pte.writable().into_bool());
+ assert_eq!(u64::from(pte), 0x3);
+
+ pte = pte.with_writable(false);
+ assert!(!pte.writable().into_bool());
+ assert_eq!(u64::from(pte), 0x1);
+
+ assert_eq!(pte.available(), 0);
+ pte = pte.with_const_available::<0x5>();
+ assert_eq!(pte.available(), 0x5);
+ assert_eq!(u64::from(pte), 0xA01);
+ }
+
+ #[test]
+ fn test_range_fields() {
+ let mut pte = TestPageTableEntry::zeroed();
+ assert_eq!(u64::from(pte), 0x0);
+
+ pte = pte.with_const_pfn::<0x123456>();
+ assert_eq!(pte.pfn(), 0x123456);
+ assert_eq!(u64::from(pte), 0x1234560000);
+
+ pte = pte.with_const_available::<0x7>();
+ assert_eq!(pte.available(), 0x7);
+ assert_eq!(u64::from(pte), 0x1234560E00);
+
+ pte = pte.with_const_available2::<0x3FF>();
+ assert_eq!(pte.available2(), 0x3FF);
+ assert_eq!(u64::from(pte), 0x3FF0_0012_3456_0E00u64);
+
+ // Test TryFrom with ?=> for MemoryType
+ pte = pte.with_mem_type(MemoryType::Device);
+ assert_eq!(pte.mem_type(), Ok(MemoryType::Device));
+ assert_eq!(u64::from(pte), 0x3FF0_0012_3456_2E00u64);
+
+ pte = pte.with_mem_type(MemoryType::Normal);
+ assert_eq!(pte.mem_type(), Ok(MemoryType::Normal));
+ assert_eq!(u64::from(pte), 0x3FF0_0012_3456_1E00u64);
+
+ // Test all valid values for mem_type
+ pte = pte.with_mem_type(MemoryType::Reserved);
+ assert_eq!(pte.mem_type(), Ok(MemoryType::Reserved));
+ assert_eq!(u64::from(pte), 0x3FF0_0012_3456_3E00u64);
+
+ // Test failure case using mem_type field which has 4 bits (0-15)
+ // MemoryType only handles 0-3, so values 4-15 should return Err
+ let mut raw = pte.into_raw();
+ // Set bits 15:12 to 7 (invalid for MemoryType)
+ raw = (raw & !::kernel::bits::genmask_u64(12..=15)) | (0x7 << 12);
+ let invalid_pte = TestPageTableEntry::from_raw(raw);
+ // Should return Err with the invalid value
+ assert_eq!(invalid_pte.mem_type(), Err(0x7));
+
+ // Test a valid value after testing invalid to ensure both cases work
+ // Set bits 15:12 to 2 (valid: Device)
+ raw = (raw & !::kernel::bits::genmask_u64(12..=15)) | (0x2 << 12);
+ let valid_pte = TestPageTableEntry::from_raw(raw);
+ assert_eq!(valid_pte.mem_type(), Ok(MemoryType::Device));
+
+ const MAX_PFN: u64 = ::kernel::bits::genmask_u64(0..=35);
+ pte = pte.with_const_pfn::<{ MAX_PFN }>();
+ assert_eq!(pte.pfn(), MAX_PFN);
+ }
+
+ #[test]
+ fn test_builder_pattern() {
+ let pte = TestPageTableEntry::zeroed()
+ .with_present(true)
+ .with_writable(true)
+ .with_const_available::<0x7>()
+ .with_const_pfn::<0xABCDEF>()
+ .with_mem_type(MemoryType::Reserved)
+ .with_const_available2::<0x3FF>();
+
+ assert!(pte.present().into_bool());
+ assert!(pte.writable().into_bool());
+ assert_eq!(pte.available(), 0x7);
+ assert_eq!(pte.pfn(), 0xABCDEF);
+ assert_eq!(pte.mem_type(), Ok(MemoryType::Reserved));
+ assert_eq!(pte.available2(), 0x3FF);
+ }
+
+ #[test]
+ fn test_raw_operations() {
+ let raw_value = 0x3FF0000031233E03u64;
+
+ let pte = TestPageTableEntry::from_raw(raw_value);
+ assert_eq!(u64::from(pte), raw_value);
+
+ assert!(pte.present().into_bool());
+ assert!(pte.writable().into_bool());
+ assert_eq!(pte.available(), 0x7);
+ assert_eq!(pte.pfn(), 0x3123);
+ assert_eq!(pte.mem_type(), Ok(MemoryType::Reserved));
+ assert_eq!(pte.available2(), 0x3FF);
+
+ // Test using direct constructor syntax TestStruct(value)
+ let pte2 = TestPageTableEntry::from_raw(raw_value);
+ assert_eq!(u64::from(pte2), raw_value);
+ }
+
+ #[test]
+ fn test_u16_bitfield() {
+ let mut ctrl = TestControlRegister::zeroed();
+
+ assert!(!ctrl.enable().into_bool());
+ assert_eq!(ctrl.mode(), 0);
+ assert_eq!(ctrl.priority(), Priority::Low);
+ assert_eq!(ctrl.priority_nibble(), 0);
+ assert_eq!(ctrl.channel(), 0);
+
+ ctrl = ctrl.with_enable(true);
+ assert!(ctrl.enable().into_bool());
+
+ ctrl = ctrl.with_const_mode::<0x5>();
+ assert_eq!(ctrl.mode(), 0x5);
+
+ // Test From conversion with =>
+ ctrl = ctrl.with_priority(Priority::High);
+ assert_eq!(ctrl.priority(), Priority::High);
+ assert_eq!(ctrl.priority_nibble(), 0x2); // High = 2 in bits 5:4
+
+ ctrl = ctrl.with_channel(0xAB);
+ assert_eq!(ctrl.channel(), 0xAB);
+
+ // Test overlapping fields
+ ctrl = ctrl.with_const_priority_nibble::<0xF>();
+ assert_eq!(ctrl.priority_nibble(), 0xF);
+ assert_eq!(ctrl.priority(), Priority::Critical); // bits 5:4 = 0x3
+
+ let ctrl2 = TestControlRegister::zeroed()
+ .with_enable(true)
+ .with_const_mode::<0x3>()
+ .with_priority(Priority::Medium)
+ .with_channel(0x42);
+
+ assert!(ctrl2.enable().into_bool());
+ assert_eq!(ctrl2.mode(), 0x3);
+ assert_eq!(ctrl2.priority(), Priority::Medium);
+ assert_eq!(ctrl2.channel(), 0x42);
+
+ let raw_value: u16 = 0x4217;
+ let ctrl3 = TestControlRegister::from_raw(raw_value);
+ assert_eq!(u16::from(ctrl3), raw_value);
+ assert!(ctrl3.enable().into_bool());
+ assert_eq!(ctrl3.priority(), Priority::Medium);
+ assert_eq!(ctrl3.priority_nibble(), 0x1);
+ assert_eq!(ctrl3.channel(), 0x42);
+ }
+
+ #[test]
+ fn test_u8_bitfield() {
+ let mut status = TestStatusRegister::zeroed();
+
+ assert!(!status.ready().into_bool());
+ assert!(!status.error().into_bool());
+ assert_eq!(status.state(), 0);
+ assert_eq!(status.reserved(), 0);
+ assert_eq!(status.full_byte(), 0);
+
+ status = status.with_ready(true);
+ assert!(status.ready().into_bool());
+ assert_eq!(status.full_byte(), 0x01);
+
+ status = status.with_error(true);
+ assert!(status.error().into_bool());
+ assert_eq!(status.full_byte(), 0x03);
+
+ status = status.with_const_state::<0x3>();
+ assert_eq!(status.state(), 0x3);
+ assert_eq!(status.full_byte(), 0x0F);
+
+ status = status.with_const_reserved::<0xA>();
+ assert_eq!(status.reserved(), 0xA);
+ assert_eq!(status.full_byte(), 0xAF);
+
+ // Test overlapping field
+ status = status.with_full_byte(0x55);
+ assert_eq!(status.full_byte(), 0x55);
+ assert!(status.ready().into_bool());
+ assert!(!status.error().into_bool());
+ assert_eq!(status.state(), 0x1);
+ assert_eq!(status.reserved(), 0x5);
+
+ let status2 = TestStatusRegister::zeroed()
+ .with_ready(true)
+ .with_const_state::<0x2>()
+ .with_const_reserved::<0x5>();
+
+ assert!(status2.ready().into_bool());
+ assert!(!status2.error().into_bool());
+ assert_eq!(status2.state(), 0x2);
+ assert_eq!(status2.reserved(), 0x5);
+ assert_eq!(status2.full_byte(), 0x59);
+
+ let raw_value: u8 = 0x59;
+ let status3 = TestStatusRegister::from_raw(raw_value);
+ assert_eq!(u8::from(status3), raw_value);
+ assert!(status3.ready().into_bool());
+ assert!(!status3.error().into_bool());
+ assert_eq!(status3.state(), 0x2);
+ assert_eq!(status3.reserved(), 0x5);
+ assert_eq!(status3.full_byte(), 0x59);
+
+ let status4 = TestStatusRegister::from_raw(0xFF);
+ assert!(status4.ready().into_bool());
+ assert!(status4.error().into_bool());
+ assert_eq!(status4.state(), 0x3);
+ assert_eq!(status4.reserved(), 0xF);
+ assert_eq!(status4.full_byte(), 0xFF);
+ }
+}

--
2.53.0