[PATCH v4 5/6] rust: Add KUNIT tests for bitfield

Joel Fernandes
2025-09-20T18:23:23Z

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

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
---
rust/kernel/bits/bitfield.rs | 349 +++++++++++++++++++++++++++++++++++
1 file changed, 349 insertions(+)

diff --git a/rust/kernel/bits/bitfield.rs b/rust/kernel/bits/bitfield.rs
index 6089f3cdbd1b..99e443580b36 100644
--- a/rust/kernel/bits/bitfield.rs
+++ b/rust/kernel/bits/bitfield.rs
@@ -341,3 +341,352 @@ fn default() -> Self {
}
};
}
+
+#[::kernel::macros::kunit_tests(kernel_bitfield)]
+mod tests {
+ use core::convert::TryFrom;
+
+ // Enum types for testing => and ?=> conversions
+ #[derive(Debug, Clone, Copy, PartialEq)]
+ enum MemoryType {
+ Unmapped = 0,
+ Normal = 1,
+ Device = 2,
+ Reserved = 3,
+ }
+
+ impl Default for MemoryType {
+ fn default() -> Self {
+ MemoryType::Unmapped
+ }
+ }
+
+ impl TryFrom<u8> for MemoryType {
+ type Error = u8;
+ fn try_from(value: u8) -> Result<Self, Self::Error> {
+ match value {
+ 0 => Ok(MemoryType::Unmapped),
+ 1 => Ok(MemoryType::Normal),
+ 2 => Ok(MemoryType::Device),
+ 3 => Ok(MemoryType::Reserved),
+ _ => Err(value),
+ }
+ }
+ }
+
+ impl From<MemoryType> for u64 {
+ fn from(mt: MemoryType) -> u64 {
+ mt as u64
+ }
+ }
+
+ #[derive(Debug, Clone, Copy, PartialEq)]
+ enum Priority {
+ Low = 0,
+ Medium = 1,
+ High = 2,
+ Critical = 3,
+ }
+
+ impl Default for Priority {
+ fn default() -> Self {
+ Priority::Low
+ }
+ }
+
+ impl From<u8> for Priority {
+ fn from(value: u8) -> Self {
+ match value & 0x3 {
+ 0 => Priority::Low,
+ 1 => Priority::Medium,
+ 2 => Priority::High,
+ _ => Priority::Critical,
+ }
+ }
+ }
+
+ impl From<Priority> for u16 {
+ fn from(p: Priority) -> u16 {
+ p as u16
+ }
+ }
+
+ bitfield! {
+ struct TestPageTableEntry: u64 {
+ 0:0 present as bool;
+ 1:1 writable as bool;
+ 11:9 available as u8;
+ 13:12 mem_type as u8 ?=> MemoryType;
+ 17:14 extended_type as u8 ?=> MemoryType; // For testing failures
+ 51:12 pfn as u64;
+ 51:12 pfn_overlap as u64;
+ 61:52 available2 as u16;
+ }
+ }
+
+ bitfield! {
+ struct TestControlRegister: u16 {
+ 0:0 enable as bool;
+ 3:1 mode as u8;
+ 5:4 priority as u8 => Priority;
+ 7:4 priority_nibble as u8;
+ 15:8 channel as u8;
+ }
+ }
+
+ bitfield! {
+ struct TestStatusRegister: u8 {
+ 0:0 ready as bool;
+ 1:1 error as bool;
+ 3:2 state as u8;
+ 7:4 reserved as u8;
+ 7:0 full_byte as u8; // For entire register
+ }
+ }
+
+ bitfield! {
+ struct TestPartialBits: u8 {
+ 0:0 ready as bool;
+ 1:1 error as bool;
+ 3:2 state as u8;
+ }
+ }
+
+ #[test]
+ fn test_single_bits() {
+ let mut pte = TestPageTableEntry::default();
+
+ assert!(!pte.present());
+ assert!(!pte.writable());
+
+ pte = pte.set_present(true);
+ assert!(pte.present());
+
+ pte = pte.set_writable(true);
+ assert!(pte.writable());
+
+ pte = pte.set_writable(false);
+ assert!(!pte.writable());
+
+ assert_eq!(pte.available(), 0);
+ pte = pte.set_available(0x5);
+ assert_eq!(pte.available(), 0x5);
+ }
+
+ #[test]
+ fn test_range_fields() {
+ let mut pte = TestPageTableEntry::default();
+
+ pte = pte.set_pfn(0x123456);
+ assert_eq!(pte.pfn(), 0x123456);
+ // Test overlapping field reads same value
+ assert_eq!(pte.pfn_overlap(), 0x123456);
+
+ pte = pte.set_available(0x7);
+ assert_eq!(pte.available(), 0x7);
+
+ pte = pte.set_available2(0x3FF);
+ assert_eq!(pte.available2(), 0x3FF);
+
+ // Test TryFrom with ?=> for MemoryType
+ pte = pte.set_mem_type(MemoryType::Device);
+ assert_eq!(pte.mem_type(), Ok(MemoryType::Device));
+
+ pte = pte.set_mem_type(MemoryType::Normal);
+ assert_eq!(pte.mem_type(), Ok(MemoryType::Normal));
+
+ // Test all valid values for mem_type
+ pte = pte.set_mem_type(MemoryType::Reserved); // Valid value: 3
+ assert_eq!(pte.mem_type(), Ok(MemoryType::Reserved));
+
+ // Test failure case using extended_type field which has 4 bits (0-15)
+ // MemoryType only handles 0-3, so values 4-15 should return Err
+ let mut raw = pte.raw();
+ // Set bits 17:14 to 7 (invalid for MemoryType)
+ raw = (raw & !::kernel::bits::genmask_u64(14..=17)) | (0x7 << 14);
+ let invalid_pte = TestPageTableEntry::from(raw);
+ // Should return Err with the invalid value
+ assert_eq!(invalid_pte.extended_type(), Err(0x7));
+
+ // Test a valid value after testing invalid to ensure both cases work
+ // Set bits 17:14 to 2 (valid: Device)
+ raw = (raw & !::kernel::bits::genmask_u64(14..=17)) | (0x2 << 14);
+ let valid_pte = TestPageTableEntry::from(raw);
+ assert_eq!(valid_pte.extended_type(), Ok(MemoryType::Device));
+
+ let max_pfn = ::kernel::bits::genmask_u64(0..=39);
+ pte = pte.set_pfn(max_pfn);
+ assert_eq!(pte.pfn(), max_pfn);
+ assert_eq!(pte.pfn_overlap(), max_pfn);
+ }
+
+ #[test]
+ fn test_builder_pattern() {
+ let pte = TestPageTableEntry::default()
+ .set_present(true)
+ .set_writable(true)
+ .set_available(0x7)
+ .set_pfn(0xABCDEF)
+ .set_mem_type(MemoryType::Reserved)
+ .set_available2(0x3FF);
+
+ assert!(pte.present());
+ assert!(pte.writable());
+ assert_eq!(pte.available(), 0x7);
+ assert_eq!(pte.pfn(), 0xABCDEF);
+ assert_eq!(pte.pfn_overlap(), 0xABCDEF);
+ assert_eq!(pte.mem_type(), Ok(MemoryType::Reserved));
+ assert_eq!(pte.available2(), 0x3FF);
+ }
+
+ #[test]
+ fn test_raw_operations() {
+ let raw_value = 0x3FF0000003123E03u64;
+
+ // Test using ::from() syntax
+ let pte = TestPageTableEntry::from(raw_value);
+ assert_eq!(pte.raw(), raw_value);
+
+ assert!(pte.present());
+ assert!(pte.writable());
+ assert_eq!(pte.available(), 0x7);
+ assert_eq!(pte.pfn(), 0x3123);
+ assert_eq!(pte.pfn_overlap(), 0x3123);
+ assert_eq!(pte.mem_type(), Ok(MemoryType::Reserved));
+ assert_eq!(pte.available2(), 0x3FF);
+
+ // Test using direct constructor syntax TestStruct(value)
+ let pte2 = TestPageTableEntry(raw_value);
+ assert_eq!(pte2.raw(), raw_value);
+ }
+
+ #[test]
+ fn test_u16_bitfield() {
+ let mut ctrl = TestControlRegister::default();
+
+ assert!(!ctrl.enable());
+ assert_eq!(ctrl.mode(), 0);
+ assert_eq!(ctrl.priority(), Priority::Low);
+ assert_eq!(ctrl.priority_nibble(), 0);
+ assert_eq!(ctrl.channel(), 0);
+
+ ctrl = ctrl.set_enable(true);
+ assert!(ctrl.enable());
+
+ ctrl = ctrl.set_mode(0x5);
+ assert_eq!(ctrl.mode(), 0x5);
+
+ // Test From conversion with =>
+ ctrl = ctrl.set_priority(Priority::High);
+ assert_eq!(ctrl.priority(), Priority::High);
+ assert_eq!(ctrl.priority_nibble(), 0x2); // High = 2 in bits 5:4
+
+ ctrl = ctrl.set_channel(0xAB);
+ assert_eq!(ctrl.channel(), 0xAB);
+
+ // Test overlapping fields
+ ctrl = ctrl.set_priority_nibble(0xF);
+ assert_eq!(ctrl.priority_nibble(), 0xF);
+ assert_eq!(ctrl.priority(), Priority::Critical); // bits 5:4 = 0x3
+
+ let ctrl2 = TestControlRegister::default()
+ .set_enable(true)
+ .set_mode(0x3)
+ .set_priority(Priority::Medium)
+ .set_channel(0x42);
+
+ assert!(ctrl2.enable());
+ 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_value);
+ assert_eq!(ctrl3.raw(), raw_value);
+ assert!(ctrl3.enable());
+ 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::default();
+
+ assert!(!status.ready());
+ assert!(!status.error());
+ assert_eq!(status.state(), 0);
+ assert_eq!(status.reserved(), 0);
+ assert_eq!(status.full_byte(), 0);
+
+ status = status.set_ready(true);
+ assert!(status.ready());
+ assert_eq!(status.full_byte(), 0x01);
+
+ status = status.set_error(true);
+ assert!(status.error());
+ assert_eq!(status.full_byte(), 0x03);
+
+ status = status.set_state(0x3);
+ assert_eq!(status.state(), 0x3);
+ assert_eq!(status.full_byte(), 0x0F);
+
+ status = status.set_reserved(0xA);
+ assert_eq!(status.reserved(), 0xA);
+ assert_eq!(status.full_byte(), 0xAF);
+
+ // Test overlapping field
+ status = status.set_full_byte(0x55);
+ assert_eq!(status.full_byte(), 0x55);
+ assert!(status.ready());
+ assert!(!status.error());
+ assert_eq!(status.state(), 0x1);
+ assert_eq!(status.reserved(), 0x5);
+
+ let status2 = TestStatusRegister::default()
+ .set_ready(true)
+ .set_state(0x2)
+ .set_reserved(0x5);
+
+ assert!(status2.ready());
+ assert!(!status2.error());
+ 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_value);
+ assert_eq!(status3.raw(), raw_value);
+ assert!(status3.ready());
+ assert!(!status3.error());
+ assert_eq!(status3.state(), 0x2);
+ assert_eq!(status3.reserved(), 0x5);
+ assert_eq!(status3.full_byte(), 0x59);
+
+ let status4 = TestStatusRegister::from(0xFF);
+ assert!(status4.ready());
+ assert!(status4.error());
+ assert_eq!(status4.state(), 0x3);
+ assert_eq!(status4.reserved(), 0xF);
+ assert_eq!(status4.full_byte(), 0xFF);
+ }
+
+ #[test]
+ fn test_partial_bitfield() {
+ // Test creating a bitfield from a runtime value that has bits set
+ // beyond what the defined fields can handle.
+ let raw_value: u8 = 0xff; // All bits set
+ let bf = TestPartialBits::from(raw_value);
+ assert_eq!(bf.raw(), 0xff);
+
+ // Test individual field extraction from the runtime value
+ assert!(bf.ready());
+ assert!(bf.error());
+ assert_eq!(bf.state(), 3); // bits 3:2 are both set
+
+ // Test overflow of setters
+ let mut bf2 = TestPartialBits::default();
+ bf2 = bf2.set_state(0x55);
+ assert_eq!(bf2.state(), 0x1);
+ }
+}
--
2.34.1