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Howlett" , Andrew Morton , Greg Kroah-Hartman , Arnd Bergmann , Christian Brauner , 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-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 657D54000C X-Stat-Signature: th9mcdtuiprd8hjxrj1t467ehri5hb13 X-Rspam-User: X-HE-Tag: 1733913450-261983 X-HE-Meta: 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 GLIojVbp 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 X-Bogosity: Unsure, tests=bogofilter, spamicity=0.499856, 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 (for mm bits) Signed-off-by: Alice Ryhl --- rust/kernel/mm/virt.rs | 71 +++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 70 insertions(+), 1 deletion(-) diff --git a/rust/kernel/mm/virt.rs b/rust/kernel/mm/virt.rs index 68c763169cf0..3a23854e14f4 100644 --- a/rust/kernel/mm/virt.rs +++ b/rust/kernel/mm/virt.rs @@ -4,7 +4,15 @@ //! Virtual memory. -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. /// @@ -100,6 +108,67 @@ pub fn zap_page_range_single(&self, address: usize, size: usize) { ) }; } + + /// Check whether the `VM_MIXEDMAP` flag is set. + /// + /// This can be used to access methods that require `VM_MIXEDMAP` to be set. + #[inline] + pub fn as_mixedmap_vma(&self) -> Option<&VmAreaMixedMap> { + 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 `VmAreaRef`. + Some(unsafe { VmAreaMixedMap::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. +/// +/// # Invariants +/// +/// The caller must hold the mmap read lock or the vma read lock. The `VM_MIXEDMAP` flag must be +/// set. +#[repr(transparent)] +pub struct VmAreaMixedMap { + vma: VmAreaRef, +} + +// Make all `VmAreaRef` methods available on `VmAreaMixedMap`. +impl Deref for VmAreaMixedMap { + type Target = VmAreaRef; + + #[inline] + fn deref(&self) -> &VmAreaRef { + &self.vma + } +} + +impl VmAreaMixedMap { + /// 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: The caller has read access and has verified that `VM_MIXEDMAP` is set. The page + // is order 0. The address is checked on the C side so it can take any value. + to_result(unsafe { bindings::vm_insert_page(self.as_ptr(), address as _, page.as_ptr()) }) + } } /// The integer type used for vma flags. -- 2.47.1.613.gc27f4b7a9f-goog