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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 Content-Type: text/plain; charset="utf-8" X-Stat-Signature: 7n7w1gz6zrgibdhzs5jqfg9tgfdsstuw X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 547064000C X-Rspam-User: X-HE-Tag: 1739444685-420955 X-HE-Meta: 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 ilHNhxZC 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 X-Bogosity: Unsure, tests=bogofilter, spamicity=0.491101, 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 Reviewed-by: Andreas Hindborg 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 a66be649f0b8..3e2eabcc2145 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. -- 2.48.1.502.g6dc24dfdaf-goog