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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 , Linus Torvalds , 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: 93o6zkq9xkutk1f6ijmt1ruz3pzj6sai X-Rspamd-Queue-Id: 83E5D1A0008 X-Rspamd-Server: rspam06 X-Rspam-User: X-HE-Tag: 1741089106-916915 X-HE-Meta: U2FsdGVkX1/sHC5mDFOrcc9/kqEZx/mVH4qjeO2ZAHv40f6NHwvtjfQIvpYFf4XYP/sc40KZdI/f/EPvA99IPDRLkr6TjjZjplhynrmn1lwgHQtYqVyZBpeQVo5bSCu23flZj+QIqh8dxcfWj+F5OymujDfbuuyEnfDhYgTO6gjmjc6E3V10c2K2/AKhw9EomCwhPT0i3O9IMEMIRQP29aOMJ8VVQRytRKSYhdJQb+NLQHA5i53xss2QBrnZkTLOhN/L7Syr9wENKeIy4MHy1jhY64WaYYbAw+Q9L6/MWo3ukKuVZosA8Rq6wpnEqK1XeMNs8fLvbnlYc31SdfiqSeehezNceSEmDSjsagAgr7ogYhIfpRm+89K2wthM8by2rnhjugkLqAjqZacVhVVm0Xfc3W5xebJ5UdZi5T0OKTSwDCRwnJQFUKrR7Es4ErUiJXyPpk6GvXPM2ng8gQsYJ2rZwbanzD4CRJBK6pjS9i29mCL2bNsrH86mxC4hpANp1WYO5AZnEzdHdncm5nJ/SjsYMVIcDTS/kd4u1uuSgVhIMwaXCg5DE2B2Or+bMNs3YDMEu0D2HsinD1tzXpIR0KNyEDjxrPgI9rgh/XyXVdtyD6GMmvJZtBXF8PtBuTZ5FukOau+5uFQkU8tskejX0XaZSx+ZCpNGB+adq6N9Oxd4/heUCmGM3FMyMbKeMLXofOLf3kv8f498M5peiVdvxA2RCdZrn8Nw3DqAXu8y4tBMOhcrjE/U+Whq3FLmH9LEMVH6+1+YdDDo2APFxP9wqpJIfvYERERHcLiQa+zUVdpXNUaUyQ+wJH3qNanaFjjDXutbu5yM7yiO0hnQVuXocFxihCoGxyOl2J6TjsG5xR4ysaJjUFj6qv8qA/6M2f3D/hbCFrHQKCCZbdj2VlpmdlisfNcJ8Y0cO/CHcjVyhlfY8ZXzdlhgJkbUu8QLL9ErEmS7aMhzAJIENVg7yMu +nEsGPbZ 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 X-Bogosity: Unsure, tests=bogofilter, spamicity=0.490716, 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. -- 2.48.1.711.g2feabab25a-goog