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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?Q1Wh/QHc6AZO8kuXs0iJu+I6/I5wAkjTr//Cqmvf/StUlRj2eWdXrM31LCIu?= =?us-ascii?Q?SIeaofSXAoVuGjuFDVae/xs1u5m/TXBKp8fkcTZJ/jjBuRshV/WlcAHGE4FP?= =?us-ascii?Q?oC21JOzmvXPpN9g56nDv5e8wCQ606d1PY66bbpWu2kkXuapgnkYb6eVcNhdS?= =?us-ascii?Q?QjmLK5JE5XhsvdOZ8+EtcS9kQriU0l3iRodJLKqt9xFKlMPljcNfMloq7C90?= =?us-ascii?Q?EKz3tooGcCnX0UvRbmxfM+USRIfB8HLAFcL0QU8IMsDaTvegQj3vxRCbXek1?= =?us-ascii?Q?ATUItW/U4U/Z7UG9PB3yS7OubwhJLPA9VWpQ9Ww4te1Dpc405Q/oIxT5yiLc?= =?us-ascii?Q?UTZB0RKQZOqnN5SzBD/Z52tMhe8z/fKVsg/yMLpnGr8/wvNmTRPQR4dQC/qi?= =?us-ascii?Q?clmtW4Pv+Mq1h3CNBWo5vOmqQdLjJEqStOkvbx/L9jVjPFvvOdYB/lVrklrp?= =?us-ascii?Q?4CofbJtZtPdE+SOwVO6LYoNCSxfedgBKab+BkfpGuk0ul36jKQjnXndetAWa?= =?us-ascii?Q?kpOOyFQ0KJxUXmtmf6vSMz5Xkm81AvPwJ73FOtFn7oZTbjykfaZdOhvbjYFO?= =?us-ascii?Q?DUh3je+gsBsG7ctT7Cm/WSJyujujSd16H5upJ8349sCre51N+r9WDYkjkb9o?= =?us-ascii?Q?nDlSc/1RlUFKHmOgDN6Xhvzn+swjq2ROLfPoK+Rfq/Nuy0PUNM56+XeSyfMV?= =?us-ascii?Q?HP6yIhHTJUPiUo6P7Rk9rTEOSg34OQfXysijlr3ODcbytb2TyEvTTiXpwTr8?= =?us-ascii?Q?sLeLQhCDrxD9MeZ3W3f7mjWp0L34duF1Exgaf29rcuADLSF5ur3/vmSt8vFk?= =?us-ascii?Q?MB13aUsVUpuU6ieDM0I/6kSPL2+4WYMPtmDGYnkXMcNF6ZHRlzwJ1uMvJV0W?= =?us-ascii?Q?lvHKw5GTNCXb8YBM82A1ZXgrcdePgbdR986NSd8KJ6xdk9RtQ777E/YHup1d?= =?us-ascii?Q?r840GtaZ2wuxvIC1kL65WIU+KY6UuIePejPyE2pOjhygDuev68LRrm5Jli8a?= =?us-ascii?Q?V1Td6+VnuA70BkH4o2h1LxPUFId6KdVtyHAUryFENufuYZISfmGieox83hdb?= =?us-ascii?Q?8PgeQnOgQuwDASNB3K0kRk9/GzdK1BWkIeDbxe3WpQ9j2RuGvwKwCZg6QtwH?= =?us-ascii?Q?WKoKg8KHwC4QekXnRbMXTpS/onvTqHh2zhA04LTT/jWBgwwwx7hCdhNpwW9G?= =?us-ascii?Q?acBJbknmrWxIMo0Tpp+DYwIZQYQlZcgOMeJe5pFf7zK9cm8i1OFQvfo0clg+?= =?us-ascii?Q?CcWpQu3J5IW/l/Bo94TO6IOYmjFRj+AtIi82ij9KdfGTiFeEZSV4O/y7VfEI?= =?us-ascii?Q?X2PestTxRyXa0dk8HnXHu1DBabgztQh/GU7dJimxfGnZzIiig26Ojpe9TCaG?= =?us-ascii?Q?OJWho8ZhY4TwLiKuXhQFM0AKtOaNihVz4pFHsdPD0YI/lmmXEaP4cIer+rDs?= =?us-ascii?Q?am7sL7EnKwPWwg8grzPNU8ndE7Afsb0oSHhQpKiyA2H4qNbc15FiXkGRBG83?= =?us-ascii?Q?QO+mKR65WuF4gm3KxO1fbUp7S9jMXQkTXqVsTKTeJIX2rSo0f6nHCIoRxJzw?= =?us-ascii?Q?jLk6jItiknbKNUf4O75txDLJjhqQdGCdrP1949nuPydWhU+gbv/QhXBede9A?= =?us-ascii?Q?EVSbhEwVcG7VMLtVrZSDPi+GUT+CFiqo38os4w2KjdxAUBM4Z54l9WPXrGf9?= =?us-ascii?Q?c06ereK7aDphXGFe/UKWq9MHE/KQf71k73fZwGvvOZZPzCl6LM6eEEuJABem?= =?us-ascii?Q?ppVAx+4Ekg=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: b428033e-6cb3-45df-d60c-08def756ffab X-MS-Exchange-CrossTenant-AuthSource: LV3PR12MB9356.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Aug 2026 03:16:56.4162 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 5vm8hqk1o2RscnTaCcgvMbvHjGSFST+RDqpRHs0cDkwdbcpLCoZpWxEJKjYC/X7wPuyoaMZQ3PQzz9APM7TA3w== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB7571 On Mon, Aug 10, 2026 at 05:34:11PM +0900, Eliot Courtney wrote: > Add bindings for area operations on bitmaps. Each one is > made safe by adding some extra checks compared to the underlying C code > (for example, checking bounds) and with additional checks to catch > likely erroneous usage if `CONFIG_RUST_BITMAP_HARDENED` is on. > > Add tests demonstrating the edge cases. > > Signed-off-by: Eliot Courtney > --- > rust/kernel/bitmap.rs | 235 ++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 235 insertions(+) > > diff --git a/rust/kernel/bitmap.rs b/rust/kernel/bitmap.rs > index 0d481d761f2a..a2557e9c5cfe 100644 > --- a/rust/kernel/bitmap.rs > +++ b/rust/kernel/bitmap.rs > @@ -10,6 +10,7 @@ > use crate::bindings; > #[cfg(not(CONFIG_RUST_BITMAP_HARDENED))] > use crate::pr_err; > +use crate::ptr::Alignment; > use core::ptr::NonNull; > > /// Represents a C bitmap. Wraps underlying C bitmap API. > @@ -503,6 +504,138 @@ pub fn next_zero_bit(&self, start: usize) -> Option { > Some(index) > } > } > + > + /// Finds a contiguous area of `nbits` zero bits at or after `start`, where the area plus > + /// `align_offset` is aligned to `align`. > + /// > + /// Returns the bit index of the start of the area, or [`None`] if no such area fitting in > + /// the bitmap exists. > + /// > + /// The returned index plus `align_offset` is a multiple of `align`. > + /// > + /// # Panics > + /// > + /// Panics if CONFIG_RUST_BITMAP_HARDENED is enabled and `start` is out of bounds. > + #[inline] > + pub fn next_zero_area_off( > + &self, > + start: usize, > + nbits: usize, > + align: Alignment, > + align_offset: usize, > + ) -> Option { > + bitmap_assert!( > + start < self.len(), > + "`start` must be < {}, was {}", > + self.len(), > + start > + ); > + > + let nr = u32::try_from(nbits).ok()?; > + > + // The C alignment and end arithmetic must not overflow, or it can read out of bounds. > + // Overflow is only possible on 32-bit. That doesn't sound optimistic. Can you add a check for 32-bit case? The rest looks good. Thanks, Yury > + let align_mask = align.as_usize() - 1; > + align_mask.checked_add(self.len())?.checked_add(nbits)?; > + > + // SAFETY: `bitmap_find_next_zero_area_off` is safe to use with an out of bounds `start` > + // value and, given the overflow check above, never reads beyond `self.len()` bits. > + let index = unsafe { > + bindings::bitmap_find_next_zero_area_off( > + self.as_ptr().cast_mut(), > + self.len(), > + start, > + nr, > + align_mask, > + align_offset, > + ) > + }; > + > + (index < self.len()).then_some(index) > + } > + > + /// Finds a contiguous area of `nbits` zero bits at or after `start`, aligned to `align`. > + /// > + /// Returns the bit index of the start of the area, or [`None`] if no such area fitting in > + /// the bitmap exists. > + /// > + /// The returned index is a multiple of `align`. > + /// > + /// # Panics > + /// > + /// Panics if CONFIG_RUST_BITMAP_HARDENED is enabled and `start` is out of bounds. > + /// > + /// # Examples > + /// > + /// ``` > + /// use kernel::alloc::{AllocError, flags::GFP_KERNEL}; > + /// use kernel::bitmap::BitmapVec; > + /// use kernel::ptr::Alignment; > + /// > + /// let mut b = BitmapVec::new(64, GFP_KERNEL)?; > + /// let unaligned = Alignment::new::<1>(); > + /// > + /// assert_eq!(Some(0), b.next_zero_area(0, 8, unaligned)); > + /// b.set(0, 5); > + /// assert_eq!(Some(5), b.next_zero_area(0, 8, unaligned)); > + /// assert_eq!(Some(8), b.next_zero_area(0, 8, Alignment::new::<8>())); > + /// assert_eq!(None, b.next_zero_area(0, 65, unaligned)); > + /// # Ok::<(), AllocError>(()) > + /// ``` > + #[inline] > + pub fn next_zero_area(&self, start: usize, nbits: usize, align: Alignment) -> Option { > + self.next_zero_area_off(start, nbits, align, 0) > + } > + > + /// Sets a contiguous area of `nbits` bits starting at `start`. > + /// > + /// If CONFIG_RUST_BITMAP_HARDENED is not enabled and the area `start..start + nbits` is out of > + /// bounds, does nothing. > + /// > + /// # Panics > + /// > + /// Panics if CONFIG_RUST_BITMAP_HARDENED is enabled and the area `start..start + nbits` is out > + /// of bounds. > + #[inline] > + pub fn set(&mut self, start: usize, nbits: usize) { > + bitmap_assert_return!( > + start > + .checked_add(nbits) > + .is_some_and(|end| end <= self.len()), > + "Area `start..start + nbits` ({}..{}) must be within bounds {}", > + start, > + start.saturating_add(nbits), > + self.len() > + ); > + // SAFETY: The area `start..start + nbits` is within bounds and a `Bitmap` is at most > + // `i32::MAX` bits, so the casts are lossless. > + unsafe { bindings::__bitmap_set(self.as_mut_ptr(), start as u32, nbits as i32) }; > + } > + > + /// Clears a contiguous area of `nbits` bits starting at `start`. > + /// > + /// If CONFIG_RUST_BITMAP_HARDENED is not enabled and the area `start..start + nbits` is out of > + /// bounds, does nothing. > + /// > + /// # Panics > + /// > + /// Panics if CONFIG_RUST_BITMAP_HARDENED is enabled and the area `start..start + nbits` is out > + /// of bounds. > + #[inline] > + pub fn clear(&mut self, start: usize, nbits: usize) { > + bitmap_assert_return!( > + start > + .checked_add(nbits) > + .is_some_and(|end| end <= self.len()), > + "Area `start..start + nbits` ({}..{}) must be within bounds {}", > + start, > + start.saturating_add(nbits), > + self.len() > + ); > + // SAFETY: The area `start..start + nbits` is within bounds and a `Bitmap` is at most > + // `i32::MAX` bits, so the casts are lossless. > + unsafe { bindings::__bitmap_clear(self.as_mut_ptr(), start as u32, nbits as i32) }; > + } > } > > #[cfg(CONFIG_RUST_BITMAP_KUNIT_TEST)] > @@ -620,4 +753,106 @@ fn bitmap_copy_and_extend() -> Result<(), AllocError> { > assert_eq!(Some(17), long_bitmap.last_bit()); > Ok(()) > } > + > + #[test] > + fn bitmap_area_set_clear_find() -> Result<(), AllocError> { > + let mut b = BitmapVec::new(128, GFP_KERNEL)?; > + let unaligned = Alignment::new::<1>(); > + > + assert_eq!(Some(0), b.next_zero_area(0, 5, unaligned)); > + b.set(0, 5); // Now contains {[0, 5)}. > + > + assert_eq!(Some(0), b.next_bit(0)); > + assert_eq!(Some(4), b.next_bit(4)); > + assert_eq!(Some(5), b.next_zero_bit(0)); > + assert_eq!(Some(5), b.next_zero_area(0, 5, unaligned)); > + assert_eq!(Some(8), b.next_zero_area(0, 5, Alignment::new::<8>())); > + > + b.set(8, 8); // Now contains {[0, 5), [8, 16)}. > + assert_eq!(Some(16), b.next_zero_area(0, 4, Alignment::new::<16>())); > + assert_eq!(Some(16), b.next_zero_area(0, 4, unaligned)); > + > + b.clear(0, 5); // Now contains {[8, 16)}. > + assert_eq!(Some(0), b.next_zero_area(0, 5, unaligned)); > + assert_eq!(Some(8), b.next_bit(0)); > + assert_eq!(Some(15), b.last_bit()); > + > + b.clear(16, 0); // Zero-length in-bounds clears are no-ops. > + assert_eq!(Some(8), b.next_bit(0)); > + assert_eq!(Some(15), b.last_bit()); > + > + // A zero-length request returns the first aligned position at or > + // after the next zero bit, even if that position's own bit is set. > + assert_eq!(Some(1), b.next_zero_area(1, 0, unaligned)); > + assert_eq!(Some(8), b.next_zero_area(1, 0, Alignment::new::<8>())); > + > + b.set(60, 10); // Now contains {[8, 16), [60, 70)}. > + assert_eq!(Some(60), b.next_bit(16)); > + assert_eq!(Some(69), b.last_bit()); > + assert_eq!(Some(16), b.next_zero_area(9, 40, unaligned)); > + assert_eq!(Some(70), b.next_zero_area(0, 45, unaligned)); > + > + b.clear(62, 6); // Now contains {[8, 16), [60, 62), [68, 70)}. > + assert_eq!(Some(62), b.next_zero_area(60, 6, unaligned)); > + assert_eq!(Some(61), b.next_bit(61)); > + assert_eq!(Some(69), b.last_bit()); > + > + b.set(64, 0); // Zero-length in-bounds sets are no-ops. > + assert_eq!(Some(62), b.next_zero_bit(62)); > + Ok(()) > + } > + > + #[test] > + fn bitmap_area_exhaustion() -> Result<(), AllocError> { > + let mut b = BitmapVec::new(64, GFP_KERNEL)?; > + let unaligned = Alignment::new::<1>(); > + > + assert_eq!(None, b.next_zero_area(0, 65, unaligned)); > + assert_eq!(None, b.next_zero_area(0, usize::MAX, unaligned)); > + assert_eq!(None, b.next_zero_area(1, usize::MAX, unaligned)); > + > + b.set_bit(0); // Now contains {[0, 1)}. > + assert_eq!(None, b.next_zero_area(0, usize::MAX, unaligned)); > + > + b.set(0, 61); // Now contains {[0, 61)}. > + assert_eq!(None, b.next_zero_area(0, 4, unaligned)); > + assert_eq!(Some(61), b.next_zero_area(0, 3, unaligned)); > + assert_eq!(None, b.next_zero_area(0, 1, Alignment::new::<64>())); > + Ok(()) > + } > + > + #[test] > + fn bitmap_area_off() -> Result<(), AllocError> { > + let mut b = BitmapVec::new(64, GFP_KERNEL)?; > + let align8 = Alignment::new::<8>(); > + > + b.set(0, 5); // Now contains {[0, 5)}. > + > + // The area plus align_offset starts at a multiple of the alignment. > + assert_eq!(Some(7), b.next_zero_area_off(0, 8, align8, 1)); > + assert_eq!(Some(5), b.next_zero_area_off(0, 8, align8, 3)); > + > + // A zero offset behaves like next_zero_area(). > + assert_eq!( > + b.next_zero_area(0, 8, align8), > + b.next_zero_area_off(0, 8, align8, 0) > + ); > + Ok(()) > + } > + > + #[test] > + #[cfg(not(CONFIG_RUST_BITMAP_HARDENED))] > + fn owned_bitmap_area_out_of_bounds() -> Result<(), AllocError> { > + let mut b = BitmapVec::new(64, GFP_KERNEL)?; > + > + // Should be ignored since out of bounds. > + b.set(64, 4); > + b.set(62, 8); > + b.set(usize::MAX, 0); > + b.clear(usize::MAX, 0); > + b.clear(2048, 8); > + assert_eq!(None, b.next_bit(0)); > + assert_eq!(None, b.next_zero_area(64, 1, Alignment::new::<1>())); > + Ok(()) > + } > } > > -- > 2.55.0