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Howlett" , Andrew Morton , Greg Kroah-Hartman , Arnd Bergmann , Jann Horn , Suren Baghdasaryan Cc: Alex Gaynor , Boqun Feng , Gary Guo , " =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= " , Benno Lossin , Andreas Hindborg , Trevor Gross , linux-kernel@vger.kernel.org, linux-mm@kvack.org, rust-for-linux@vger.kernel.org, Alice Ryhl X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 596AAA000C X-Stat-Signature: acngupkoyrguisms6yf51swx6cy35ipi X-HE-Tag: 1744104246-598346 X-HE-Meta: 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 rDqfF7I3 gRF4cHqGSnx5WSYojfRuQoyOZcPIRF41ZsZwtu1nzRnHFekenTfPIZN9g8PBKnNX4gghjvDiJmSx2LUD6ceyrOcgpshpF7azJ9vjxHcL5aWYasr3hI+rCkiJ0gkxFlvciorInCzTWQBIyXurBGtDlRd4mJW1Rh9D+6ohZVZ68kvVcXl4G9VsPKSPCXMt5hOqzVJXup3kIkHULMgaUR2lkFOsgMcsaa85jbzyy51habruTPr3Gs23ZSOo/rNlrpF6Ac5LtenMCqZSC5lpL2fuEq+vjyRACBWY2f3T3BrhFxABj2mtUL/RnndHpbGWoVLwtKD0uXDbktVKo42L7neqx9K2dRM+leUyu2BsRznp8DejkN09IuHaQFyQI1XOYjOuG0qIQr/a86wPyv1PJ/YFVMBn6Bg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.414524, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The vm_insert_page method is only usable on vmas with the VM_MIXEDMAP flag, so we introduce a new type to keep track of such vmas. The approach used in this patch assumes that we will not need to encode many flag combinations in the type. I don't think we need to encode more than VM_MIXEDMAP and VM_PFNMAP as things are now. However, if that becomes necessary, using generic parameters in a single type would scale better as the number of flags increases. Acked-by: Lorenzo Stoakes Acked-by: Liam R. Howlett Reviewed-by: Andreas Hindborg Reviewed-by: Gary Guo Signed-off-by: Alice Ryhl --- rust/kernel/mm/virt.rs | 79 +++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 78 insertions(+), 1 deletion(-) diff --git a/rust/kernel/mm/virt.rs b/rust/kernel/mm/virt.rs index a66be649f0b8d3dfae8ce2d18b70cb2b283fb7fe..3e2eabcc21450497a02ffa1ed1f31f3e7e7e1b6b 100644 --- a/rust/kernel/mm/virt.rs +++ b/rust/kernel/mm/virt.rs @@ -14,7 +14,15 @@ //! ensures that you can't, for example, accidentally call a function that requires holding the //! write lock when you only hold the read lock. -use crate::{bindings, mm::MmWithUser, types::Opaque}; +use crate::{ + bindings, + error::{to_result, Result}, + mm::MmWithUser, + page::Page, + types::Opaque, +}; + +use core::ops::Deref; /// A wrapper for the kernel's `struct vm_area_struct` with read access. /// @@ -119,6 +127,75 @@ pub fn zap_page_range_single(&self, address: usize, size: usize) { bindings::zap_page_range_single(self.as_ptr(), address, size, core::ptr::null_mut()) }; } + + /// If the [`VM_MIXEDMAP`] flag is set, returns a [`VmaMixedMap`] to this VMA, otherwise + /// returns `None`. + /// + /// This can be used to access methods that require [`VM_MIXEDMAP`] to be set. + /// + /// [`VM_MIXEDMAP`]: flags::MIXEDMAP + #[inline] + pub fn as_mixedmap_vma(&self) -> Option<&VmaMixedMap> { + if self.flags() & flags::MIXEDMAP != 0 { + // SAFETY: We just checked that `VM_MIXEDMAP` is set. All other requirements are + // satisfied by the type invariants of `VmaRef`. + Some(unsafe { VmaMixedMap::from_raw(self.as_ptr()) }) + } else { + None + } + } +} + +/// A wrapper for the kernel's `struct vm_area_struct` with read access and [`VM_MIXEDMAP`] set. +/// +/// It represents an area of virtual memory. +/// +/// This struct is identical to [`VmaRef`] except that it must only be used when the +/// [`VM_MIXEDMAP`] flag is set on the vma. +/// +/// # Invariants +/// +/// The caller must hold the mmap read lock or the vma read lock. The `VM_MIXEDMAP` flag must be +/// set. +/// +/// [`VM_MIXEDMAP`]: flags::MIXEDMAP +#[repr(transparent)] +pub struct VmaMixedMap { + vma: VmaRef, +} + +// Make all `VmaRef` methods available on `VmaMixedMap`. +impl Deref for VmaMixedMap { + type Target = VmaRef; + + #[inline] + fn deref(&self) -> &VmaRef { + &self.vma + } +} + +impl VmaMixedMap { + /// Access a virtual memory area given a raw pointer. + /// + /// # Safety + /// + /// Callers must ensure that `vma` is valid for the duration of 'a, and that the mmap read lock + /// (or stronger) is held for at least the duration of 'a. The `VM_MIXEDMAP` flag must be set. + #[inline] + pub unsafe fn from_raw<'a>(vma: *const bindings::vm_area_struct) -> &'a Self { + // SAFETY: The caller ensures that the invariants are satisfied for the duration of 'a. + unsafe { &*vma.cast() } + } + + /// Maps a single page at the given address within the virtual memory area. + /// + /// This operation does not take ownership of the page. + #[inline] + pub fn vm_insert_page(&self, address: usize, page: &Page) -> Result { + // SAFETY: By the type invariant of `Self` caller has read access and has verified that + // `VM_MIXEDMAP` is set. By invariant on `Page` the page has order 0. + to_result(unsafe { bindings::vm_insert_page(self.as_ptr(), address, page.as_ptr()) }) + } } /// The integer type used for vma flags.