Merge branch 'master' into next

Cargo.toml

@@ -29,14 +29,16 @@ edition = "2018"
 bit_field = "0.10.1"
 bitflags = "1.3.2"
 volatile = "0.4.4"
+rustversion = "1.0.5"
 
 [features]
 default = [ "nightly", "instructions" ]
 instructions = []
-nightly = [ "const_fn", "abi_x86_interrupt", "asm_const", "doc_cfg" ]
+nightly = [ "const_fn", "step_trait", "abi_x86_interrupt", "asm_const", "doc_cfg" ]
 abi_x86_interrupt = []
 const_fn = []
 asm_const = []
+step_trait = []
 doc_cfg = []
 
 [package.metadata.release]

src/addr.rs

@@ -1,12 +1,19 @@
 //! Physical and virtual addresses manipulation
 
+#[cfg(feature = "step_trait")]
+use core::convert::TryFrom;
 use core::fmt;
+#[cfg(feature = "step_trait")]
+use core::iter::Step;
 use core::ops::{Add, AddAssign, Sub, SubAssign};
 
 use crate::structures::paging::page_table::PageTableLevel;
 use crate::structures::paging::{PageOffset, PageTableIndex};
 use bit_field::BitField;
 
+#[cfg(feature = "step_trait")]
+const ADDRESS_SPACE_SIZE: u64 = 0x1_0000_0000_0000;
+
 /// A canonical 64-bit virtual memory address.
 ///
 /// This is a wrapper type around an `u64`, so it is always 8 bytes, even when compiled
@@ -40,9 +47,18 @@ pub struct PhysAddr(u64);
 /// a valid sign extension and are not null either. So automatic sign extension would have
 /// overwritten possibly meaningful bits. This likely indicates a bug, for example an invalid
 /// address calculation.
-#[derive(Debug)]
+///
+/// Contains the invalid address.
 pub struct VirtAddrNotValid(pub u64);
 
+impl core::fmt::Debug for VirtAddrNotValid {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_tuple("VirtAddrNotValid")
+            .field(&format_args!("{:#x}", self.0))
+            .finish()
+    }
+}
+
 impl VirtAddr {
     /// Creates a new canonical virtual address.
     ///
@@ -70,7 +86,7 @@ impl VirtAddr {
         match addr.get_bits(47..64) {
             0 | 0x1ffff => Ok(VirtAddr(addr)),     // address is canonical
             1 => Ok(VirtAddr::new_truncate(addr)), // address needs sign extension
-            other => Err(VirtAddrNotValid(other)),
+            _ => Err(VirtAddrNotValid(addr)),
         }
     }
 
@@ -322,12 +338,81 @@ impl Sub<VirtAddr> for VirtAddr {
     }
 }
 
+#[cfg(feature = "step_trait")]
+impl Step for VirtAddr {
+    fn steps_between(start: &Self, end: &Self) -> Option<usize> {
+        let mut steps = end.0.checked_sub(start.0)?;
+
+        // Check if we jumped the gap.
+        if end.0.get_bit(47) && !start.0.get_bit(47) {
+            steps = steps.checked_sub(0xffff_0000_0000_0000).unwrap();
+        }
+
+        usize::try_from(steps).ok()
+    }
+
+    fn forward_checked(start: Self, count: usize) -> Option<Self> {
+        let offset = u64::try_from(count).ok()?;
+        if offset > ADDRESS_SPACE_SIZE {
+            return None;
+        }
+
+        let mut addr = start.0.checked_add(offset)?;
+
+        match addr.get_bits(47..) {
+            0x1 => {
+                // Jump the gap by sign extending the 47th bit.
+                addr.set_bits(47.., 0x1ffff);
+            }
+            0x2 => {
+                // Address overflow
+                return None;
+            }
+            _ => {}
+        }
+
+        Some(Self::new(addr))
+    }
+
+    fn backward_checked(start: Self, count: usize) -> Option<Self> {
+        let offset = u64::try_from(count).ok()?;
+        if offset > ADDRESS_SPACE_SIZE {
+            return None;
+        }
+
+        let mut addr = start.0.checked_sub(offset)?;
+
+        match addr.get_bits(47..) {
+            0x1fffe => {
+                // Jump the gap by sign extending the 47th bit.
+                addr.set_bits(47.., 0);
+            }
+            0x1fffd => {
+                // Address underflow
+                return None;
+            }
+            _ => {}
+        }
+
+        Some(Self::new(addr))
+    }
+}
+
 /// A passed `u64` was not a valid physical address.
 ///
 /// This means that bits 52 to 64 were not all null.
-#[derive(Debug)]
+///
+/// Contains the invalid address.
 pub struct PhysAddrNotValid(pub u64);
 
+impl core::fmt::Debug for PhysAddrNotValid {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_tuple("PhysAddrNotValid")
+            .field(&format_args!("{:#x}", self.0))
+            .finish()
+    }
+}
+
 impl PhysAddr {
     /// Creates a new physical address.
     ///
@@ -367,7 +452,7 @@ impl PhysAddr {
     pub fn try_new(addr: u64) -> Result<PhysAddr, PhysAddrNotValid> {
         match addr.get_bits(52..64) {
             0 => Ok(PhysAddr(addr)), // address is valid
-            other => Err(PhysAddrNotValid(other)),
+            _ => Err(PhysAddrNotValid(addr)),
         }
     }
 
@@ -540,8 +625,7 @@ impl Sub<PhysAddr> for PhysAddr {
 ///
 /// Returns the greatest `x` with alignment `align` so that `x <= addr`.
 ///
-/// Panics if the alignment is not a power of two. Without the `const_fn`
-/// feature, the panic message will be "index out of bounds".
+/// Panics if the alignment is not a power of two.
 #[inline]
 pub const fn align_down(addr: u64, align: u64) -> u64 {
     assert!(align.is_power_of_two(), "`align` must be a power of two");
@@ -552,8 +636,7 @@ pub const fn align_down(addr: u64, align: u64) -> u64 {
 ///
 /// Returns the smallest `x` with alignment `align` so that `x >= addr`.
 ///
-/// Panics if the alignment is not a power of two. Without the `const_fn`
-/// feature, the panic message will be "index out of bounds".
+/// Panics if the alignment is not a power of two.
 #[inline]
 pub const fn align_up(addr: u64, align: u64) -> u64 {
     assert!(align.is_power_of_two(), "`align` must be a power of two");
@@ -577,6 +660,120 @@ mod tests {
         assert_eq!(VirtAddr::new_truncate(123 << 47), VirtAddr(0xfffff << 47));
     }
 
+    #[test]
+    #[cfg(feature = "step_trait")]
+    fn virtaddr_step_forward() {
+        assert_eq!(Step::forward(VirtAddr(0), 0), VirtAddr(0));
+        assert_eq!(Step::forward(VirtAddr(0), 1), VirtAddr(1));
+        assert_eq!(
+            Step::forward(VirtAddr(0x7fff_ffff_ffff), 1),
+            VirtAddr(0xffff_8000_0000_0000)
+        );
+        assert_eq!(
+            Step::forward(VirtAddr(0xffff_8000_0000_0000), 1),
+            VirtAddr(0xffff_8000_0000_0001)
+        );
+        assert_eq!(
+            Step::forward_checked(VirtAddr(0xffff_ffff_ffff_ffff), 1),
+            None
+        );
+        assert_eq!(
+            Step::forward(VirtAddr(0x7fff_ffff_ffff), 0x1234_5678_9abd),
+            VirtAddr(0xffff_9234_5678_9abc)
+        );
+        assert_eq!(
+            Step::forward(VirtAddr(0x7fff_ffff_ffff), 0x8000_0000_0000),
+            VirtAddr(0xffff_ffff_ffff_ffff)
+        );
+        assert_eq!(
+            Step::forward(VirtAddr(0x7fff_ffff_ff00), 0x8000_0000_00ff),
+            VirtAddr(0xffff_ffff_ffff_ffff)
+        );
+        assert_eq!(
+            Step::forward_checked(VirtAddr(0x7fff_ffff_ff00), 0x8000_0000_0100),
+            None
+        );
+        assert_eq!(
+            Step::forward_checked(VirtAddr(0x7fff_ffff_ffff), 0x8000_0000_0001),
+            None
+        );
+    }
+
+    #[test]
+    #[cfg(feature = "step_trait")]
+    fn virtaddr_step_backward() {
+        assert_eq!(Step::backward(VirtAddr(0), 0), VirtAddr(0));
+        assert_eq!(Step::backward_checked(VirtAddr(0), 1), None);
+        assert_eq!(Step::backward(VirtAddr(1), 1), VirtAddr(0));
+        assert_eq!(
+            Step::backward(VirtAddr(0xffff_8000_0000_0000), 1),
+            VirtAddr(0x7fff_ffff_ffff)
+        );
+        assert_eq!(
+            Step::backward(VirtAddr(0xffff_8000_0000_0001), 1),
+            VirtAddr(0xffff_8000_0000_0000)
+        );
+        assert_eq!(
+            Step::backward(VirtAddr(0xffff_9234_5678_9abc), 0x1234_5678_9abd),
+            VirtAddr(0x7fff_ffff_ffff)
+        );
+        assert_eq!(
+            Step::backward(VirtAddr(0xffff_8000_0000_0000), 0x8000_0000_0000),
+            VirtAddr(0)
+        );
+        assert_eq!(
+            Step::backward(VirtAddr(0xffff_8000_0000_0000), 0x7fff_ffff_ff01),
+            VirtAddr(0xff)
+        );
+        assert_eq!(
+            Step::backward_checked(VirtAddr(0xffff_8000_0000_0000), 0x8000_0000_0001),
+            None
+        );
+    }
+
+    #[test]
+    #[cfg(feature = "step_trait")]
+    fn virtaddr_steps_between() {
+        assert_eq!(Step::steps_between(&VirtAddr(0), &VirtAddr(0)), Some(0));
+        assert_eq!(Step::steps_between(&VirtAddr(0), &VirtAddr(1)), Some(1));
+        assert_eq!(Step::steps_between(&VirtAddr(1), &VirtAddr(0)), None);
+        assert_eq!(
+            Step::steps_between(
+                &VirtAddr(0x7fff_ffff_ffff),
+                &VirtAddr(0xffff_8000_0000_0000)
+            ),
+            Some(1)
+        );
+        assert_eq!(
+            Step::steps_between(
+                &VirtAddr(0xffff_8000_0000_0000),
+                &VirtAddr(0x7fff_ffff_ffff)
+            ),
+            None
+        );
+        assert_eq!(
+            Step::steps_between(
+                &VirtAddr(0xffff_8000_0000_0000),
+                &VirtAddr(0xffff_8000_0000_0000)
+            ),
+            Some(0)
+        );
+        assert_eq!(
+            Step::steps_between(
+                &VirtAddr(0xffff_8000_0000_0000),
+                &VirtAddr(0xffff_8000_0000_0001)
+            ),
+            Some(1)
+        );
+        assert_eq!(
+            Step::steps_between(
+                &VirtAddr(0xffff_8000_0000_0001),
+                &VirtAddr(0xffff_8000_0000_0000)
+            ),
+            None
+        );
+    }
+
     #[test]
     pub fn test_align_up() {
         // align 1

src/lib.rs

@@ -3,10 +3,9 @@
 
 #![cfg_attr(not(test), no_std)]
 #![cfg_attr(feature = "const_fn", feature(const_mut_refs))] // GDT add_entry()
-#![cfg_attr(feature = "const_fn", feature(const_fn_fn_ptr_basics))] // IDT new()
-#![cfg_attr(feature = "const_fn", feature(const_fn_trait_bound))] // PageSize marker trait
 #![cfg_attr(feature = "asm_const", feature(asm_const))]
 #![cfg_attr(feature = "abi_x86_interrupt", feature(abi_x86_interrupt))]
+#![cfg_attr(feature = "step_trait", feature(step_trait))]
 #![cfg_attr(feature = "doc_cfg", feature(doc_cfg))]
 #![warn(missing_docs)]
 #![deny(missing_debug_implementations)]
@@ -17,37 +16,6 @@ use core::sync::atomic::{AtomicBool, Ordering};
 
 pub use crate::addr::{align_down, align_up, PhysAddr, VirtAddr};
 
-/// Makes a function const only when `feature = "const_fn"` is enabled.
-///
-/// This is needed for const functions with bounds on their generic parameters,
-/// such as those in `Page` and `PhysFrame` and many more.
-macro_rules! const_fn {
-    (
-        $(#[$attr:meta])*
-        $sv:vis fn $($fn:tt)*
-    ) => {
-        $(#[$attr])*
-        #[cfg(feature = "const_fn")]
-        $sv const fn $($fn)*
-
-        $(#[$attr])*
-        #[cfg(not(feature = "const_fn"))]
-        $sv fn $($fn)*
-    };
-    (
-        $(#[$attr:meta])*
-        $sv:vis unsafe fn $($fn:tt)*
-    ) => {
-        $(#[$attr])*
-        #[cfg(feature = "const_fn")]
-        $sv const unsafe fn $($fn)*
-
-        $(#[$attr])*
-        #[cfg(not(feature = "const_fn"))]
-        $sv unsafe fn $($fn)*
-    };
-}
-
 pub mod addr;
 pub mod instructions;
 pub mod registers;