seq-file borrow

.github/workflows/busybox.config

@@ -196,7 +196,7 @@ CONFIG_GZIP_FAST=0
 # Coreutils
 #
 # CONFIG_BASENAME is not set
-# CONFIG_CAT is not set
+CONFIG_CAT=y
 # CONFIG_FEATURE_CATN is not set
 # CONFIG_FEATURE_CATV is not set
 # CONFIG_CHGRP is not set
@@ -209,7 +209,7 @@ CONFIG_GZIP_FAST=0
 # CONFIG_CP is not set
 # CONFIG_FEATURE_CP_LONG_OPTIONS is not set
 # CONFIG_FEATURE_CP_REFLINK is not set
-# CONFIG_CUT is not set
+CONFIG_CUT=y
 # CONFIG_DATE is not set
 # CONFIG_FEATURE_DATE_ISOFMT is not set
 # CONFIG_FEATURE_DATE_NANO is not set
@@ -263,9 +263,9 @@ CONFIG_GZIP_FAST=0
 # CONFIG_SHA512SUM is not set
 # CONFIG_SHA3SUM is not set
 # CONFIG_FEATURE_MD5_SHA1_SUM_CHECK is not set
-# CONFIG_MKDIR is not set
+CONFIG_MKDIR=y
 # CONFIG_MKFIFO is not set
-# CONFIG_MKNOD is not set
+CONFIG_MKNOD=y
 # CONFIG_MKTEMP is not set
 # CONFIG_MV is not set
 # CONFIG_NICE is not set
@@ -280,7 +280,7 @@ CONFIG_GZIP_FAST=0
 # CONFIG_READLINK is not set
 # CONFIG_FEATURE_READLINK_FOLLOW is not set
 # CONFIG_REALPATH is not set
-# CONFIG_RM is not set
+CONFIG_RM=y
 # CONFIG_RMDIR is not set
 # CONFIG_SEQ is not set
 # CONFIG_SHRED is not set
@@ -449,7 +449,7 @@ CONFIG_FEATURE_VI_UNDO_QUEUE_MAX=0
 # CONFIG_FEATURE_FIND_REGEX is not set
 # CONFIG_FEATURE_FIND_CONTEXT is not set
 # CONFIG_FEATURE_FIND_LINKS is not set
-# CONFIG_GREP is not set
+CONFIG_GREP=y
 # CONFIG_EGREP is not set
 # CONFIG_FGREP is not set
 # CONFIG_FEATURE_GREP_CONTEXT is not set
@@ -635,7 +635,7 @@ CONFIG_DEFAULT_DEPMOD_FILE="modules.dep"
 # CONFIG_MKSWAP is not set
 # CONFIG_FEATURE_MKSWAP_UUID is not set
 # CONFIG_MORE is not set
-# CONFIG_MOUNT is not set
+CONFIG_MOUNT=y
 # CONFIG_FEATURE_MOUNT_FAKE is not set
 # CONFIG_FEATURE_MOUNT_VERBOSE is not set
 # CONFIG_FEATURE_MOUNT_HELPERS is not set

.github/workflows/ci.yaml

@@ -375,6 +375,11 @@ jobs:
           grep '] rust_semaphore_c: Rust semaphore sample (in C, for comparison) (init)$' qemu-stdout.log
           grep '] rust_semaphore_c: Rust semaphore sample (in C, for comparison) (exit)$' qemu-stdout.log
 
+      - run: |
+          grep '] rust_seq_file: Rust seq_file sample (init)$'   qemu-stdout.log
+          grep '] rust_seq_file: Rust seq_file sample (exit)$'   qemu-stdout.log
+          test $(grep -c 'rust_seq_file: device opened this many times: 2' qemu-stdout.log) -eq 2
+
       # Report
       - run: |
           ls -l \

.github/workflows/kernel-arm-debug.config

@@ -1780,6 +1780,7 @@ CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
 CONFIG_SAMPLE_RUST_RANDOM=m
+CONFIG_SAMPLE_RUST_SEQ_FILE=m
 # CONFIG_STRICT_DEVMEM is not set
 
 #

.github/workflows/kernel-arm-release.config

@@ -1704,6 +1704,7 @@ CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
 CONFIG_SAMPLE_RUST_RANDOM=m
+CONFIG_SAMPLE_RUST_SEQ_FILE=m
 # CONFIG_STRICT_DEVMEM is not set
 
 #

.github/workflows/kernel-arm64-debug.config

@@ -1069,7 +1069,7 @@ CONFIG_DCACHE_WORD_ACCESS=y
 #
 # Pseudo filesystems
 #
-# CONFIG_PROC_FS is not set
+CONFIG_PROC_FS=y
 # CONFIG_PROC_CHILDREN is not set
 # CONFIG_SYSFS is not set
 # CONFIG_HUGETLBFS is not set
@@ -1432,6 +1432,7 @@ CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
 CONFIG_SAMPLE_RUST_RANDOM=m
+CONFIG_SAMPLE_RUST_SEQ_FILE=m
 
 #
 # arm64 Debugging

.github/workflows/kernel-arm64-release.config

@@ -1064,7 +1064,7 @@ CONFIG_DCACHE_WORD_ACCESS=y
 #
 # Pseudo filesystems
 #
-# CONFIG_PROC_FS is not set
+CONFIG_PROC_FS=y
 # CONFIG_PROC_CHILDREN is not set
 # CONFIG_SYSFS is not set
 # CONFIG_HUGETLBFS is not set
@@ -1350,6 +1350,7 @@ CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
 CONFIG_SAMPLE_RUST_RANDOM=m
+CONFIG_SAMPLE_RUST_SEQ_FILE=m
 
 #
 # arm64 Debugging

.github/workflows/kernel-ppc64le-debug.config

@@ -1492,6 +1492,7 @@ CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
 CONFIG_SAMPLE_RUST_RANDOM=m
+CONFIG_SAMPLE_RUST_SEQ_FILE=m
 CONFIG_ARCH_HAS_DEVMEM_IS_ALLOWED=y
 # CONFIG_STRICT_DEVMEM is not set
 

.github/workflows/kernel-ppc64le-release.config

@@ -1454,6 +1454,7 @@ CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
 CONFIG_SAMPLE_RUST_RANDOM=m
+CONFIG_SAMPLE_RUST_SEQ_FILE=m
 CONFIG_ARCH_HAS_DEVMEM_IS_ALLOWED=y
 # CONFIG_STRICT_DEVMEM is not set
 

.github/workflows/kernel-riscv64-debug.config

@@ -1286,6 +1286,7 @@ CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
 CONFIG_SAMPLE_RUST_RANDOM=m
+CONFIG_SAMPLE_RUST_SEQ_FILE=m
 # CONFIG_STRICT_DEVMEM is not set
 
 #

.github/workflows/kernel-riscv64-release.config

@@ -1202,6 +1202,7 @@ CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
 CONFIG_SAMPLE_RUST_RANDOM=m
+CONFIG_SAMPLE_RUST_SEQ_FILE=m
 # CONFIG_STRICT_DEVMEM is not set
 
 #

.github/workflows/kernel-x86_64-debug.config

@@ -1059,7 +1059,7 @@ CONFIG_DCACHE_WORD_ACCESS=y
 #
 # Pseudo filesystems
 #
-# CONFIG_PROC_FS is not set
+CONFIG_PROC_FS=y
 # CONFIG_PROC_CHILDREN is not set
 CONFIG_KERNFS=y
 CONFIG_SYSFS=y
@@ -1444,6 +1444,7 @@ CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
 CONFIG_SAMPLE_RUST_RANDOM=m
+CONFIG_SAMPLE_RUST_SEQ_FILE=m
 CONFIG_ARCH_HAS_DEVMEM_IS_ALLOWED=y
 # CONFIG_STRICT_DEVMEM is not set
 

.github/workflows/kernel-x86_64-release.config

@@ -1392,6 +1392,7 @@ CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
 CONFIG_SAMPLE_RUST_RANDOM=m
+CONFIG_SAMPLE_RUST_SEQ_FILE=m
 CONFIG_ARCH_HAS_DEVMEM_IS_ALLOWED=y
 # CONFIG_STRICT_DEVMEM is not set
 

.github/workflows/qemu-init.sh

@@ -37,4 +37,15 @@ busybox insmod rust_module_parameters_loadable_custom.ko \
 busybox  rmmod rust_module_parameters_loadable_default.ko
 busybox  rmmod rust_module_parameters_loadable_custom.ko
 
+busybox insmod rust_seq_file.ko
+busybox mkdir proc
+busybox mount -t proc proc /proc
+export RUST_SEQ_MINOR=$(busybox cat /proc/misc | busybox grep rust_seq_file | busybox cut -d ' ' -f 1)
+busybox mknod /dev/rust_seq_file0 c 10 $RUST_SEQ_MINOR
+busybox cat /dev/rust_seq_file0
+busybox cat /dev/rust_seq_file0
+busybox cat /proc/rust_seq_file
+busybox rm /dev/rust_seq_file0
+busybox rmmod rust_seq_file.ko
+
 busybox reboot -f

.github/workflows/qemu-initramfs.desc

@@ -14,6 +14,7 @@ file    /rust_miscdev.ko            samples/rust/rust_miscdev.ko            0755
 file    /rust_stack_probing.ko      samples/rust/rust_stack_probing.ko      0755 0 0
 file    /rust_semaphore.ko          samples/rust/rust_semaphore.ko          0755 0 0
 file    /rust_semaphore_c.ko        samples/rust/rust_semaphore_c.ko        0755 0 0
+file    /rust_seq_file.ko           samples/rust/rust_seq_file.ko           0755 0 0
 
 file    /rust_module_parameters_loadable_default.ko  samples/rust/rust_module_parameters_loadable_default.ko  0755 0 0
 file    /rust_module_parameters_loadable_custom.ko   samples/rust/rust_module_parameters_loadable_custom.ko   0755 0 0

rust/kernel/bindings_helper.h

@@ -4,7 +4,9 @@
 #include <linux/errname.h>
 #include <linux/fs.h>
 #include <linux/module.h>
+#include <linux/proc_fs.h>
 #include <linux/random.h>
+#include <linux/seq_file.h>
 #include <linux/slab.h>
 #include <linux/sysctl.h>
 #include <linux/uaccess.h>

rust/kernel/lib.rs

@@ -62,7 +62,12 @@ pub mod module_param;
 mod build_assert;
 pub mod prelude;
 pub mod print;
+
+#[cfg(CONFIG_PROC_FS)]
+pub mod proc_fs;
+
 pub mod random;
+pub mod seq_file;
 mod static_assert;
 pub mod sync;
 
@@ -80,7 +85,7 @@ pub mod user_ptr;
 pub use build_error::build_error;
 
 pub use crate::error::{Error, Result};
-pub use crate::types::{Mode, ScopeGuard};
+pub use crate::types::{Mode, ScopeGuard, UnsafeReference};
 
 /// Page size defined in terms of the `PAGE_SHIFT` macro from C.
 ///

rust/kernel/proc_fs.rs

@@ -0,0 +1,101 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Type for defining `proc` files.
+//!
+//! This module allows Rust devices to create entries in `/proc` from a
+//! [`bindings::proc_ops`] vtable.
+//!
+//! C header: [`include/linux/proc_fs.h`](../../../include/linux/proc_fs.h)
+//!
+//! Reference: <https://www.kernel.org/doc/html/latest/filesystems/proc.html>
+
+use core::{
+    marker::{PhantomData, Sync},
+    ptr,
+};
+
+use crate::{
+    bindings, c_types,
+    seq_file::{SeqFileOperationsVTable, SeqOperations},
+    str::CStr,
+    types::PointerWrapper,
+    Error, Result,
+};
+
+/// An entry under `/proc` containing data of type `T`.
+///
+/// This is the Rust equivalent to [`proc_dir_entry`] on the C side.
+///
+/// # Invariants
+///
+/// The [`ProcDirEntry::proc_dir_entry`] is a valid pointer.
+/// [`ProcDirEntry::data`] points to the PDE data of
+/// [`ProcDirEntry::proc_dir_entry`].
+/// [`ProcDirEntry::data`] was created by a call to `T::into_pointer`.
+///
+/// [`proc_dir_entry`]: ../../../fs/proc/internal.h
+pub struct ProcDirEntry<T: PointerWrapper> {
+    proc_dir_entry: *mut bindings::proc_dir_entry,
+    data: *const c_types::c_void,
+    _wrapper: PhantomData<T>,
+}
+
+// SAFETY: The `proc_dir_entry` and `data` raw pointers aren't accessible.
+unsafe impl<T: PointerWrapper> Sync for ProcDirEntry<T> {}
+
+impl<T: PointerWrapper> Drop for ProcDirEntry<T> {
+    fn drop(&mut self) {
+        // SAFETY: Calling a C function. `proc_dir_entry` is a valid pointer to
+        // a `bindings::proc_dir_entry` because it was created by a call to
+        // `proc_create_data` which only returns valid pointers.
+        unsafe {
+            bindings::proc_remove(self.proc_dir_entry);
+        }
+        // SAFETY: `self.data` was created by a call to `T::into_pointer`.
+        unsafe { drop(T::from_pointer(self.data)) }
+    }
+}
+
+impl<T: PointerWrapper> ProcDirEntry<T> {
+    /// Create a seq_file entry in `/proc` containing data of type `S`.
+    ///
+    /// Corresponds to [`proc_create_seq_private`] on the C side.
+    ///
+    /// [`proc_create_seq_private`]: ../../../fs/proc/generic.c
+    pub fn new_seq_private<S>(name: &CStr, data: T) -> Result<Self>
+    where
+        S: SeqOperations<DataWrapper = T>,
+    {
+        let data = data.into_pointer();
+        let name = name.as_char_ptr();
+
+        // SAFETY: Calling a C function. The vtable for `S` expects a
+        // `S::DataWrapper = T` pointer in the data field of the associated
+        // `proc_dir_entry`.  `name` is guaranteed to be null terminated
+        // because it is of type `CStr`.
+        let proc_dir_entry = unsafe {
+            bindings::proc_create_seq_private(
+                name,
+                0,
+                ptr::null_mut(),
+                SeqFileOperationsVTable::<S>::build(),
+                0,
+                data as *mut c_types::c_void,
+            )
+        };
+        if proc_dir_entry.is_null() {
+            // SAFETY: `data` was created with a call to `T::into_pointer`.
+            drop(unsafe { T::from_pointer(data) });
+            Err(Error::ENOMEM)
+        } else {
+            // INVARIANT: `proc_dir_entry` is a valid pointer.
+            // The `data` points to the data stored in `proc_dir_entry`, and
+            // `data` was created by `T::into_pointer`.
+            Ok(ProcDirEntry {
+                proc_dir_entry,
+                data,
+                _wrapper: PhantomData,
+            })
+        }
+    }
+}