Seq file proc redo

.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

@@ -324,6 +324,11 @@ 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

@@ -1665,6 +1665,7 @@ CONFIG_SAMPLE_RUST_MISCDEV=m
 CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
+CONFIG_SAMPLE_RUST_SEQ_FILE=m
 # CONFIG_STRICT_DEVMEM is not set
 
 #

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

@@ -1589,6 +1589,7 @@ CONFIG_SAMPLE_RUST_MISCDEV=m
 CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=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
@@ -1431,6 +1431,7 @@ CONFIG_SAMPLE_RUST_MISCDEV=m
 CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=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
@@ -1349,6 +1349,7 @@ CONFIG_SAMPLE_RUST_MISCDEV=m
 CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
+CONFIG_SAMPLE_RUST_SEQ_FILE=m
 
 #
 # arm64 Debugging

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

@@ -1491,6 +1491,7 @@ CONFIG_SAMPLE_RUST_MISCDEV=m
 CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=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

@@ -1453,6 +1453,7 @@ CONFIG_SAMPLE_RUST_MISCDEV=m
 CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=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

@@ -1353,6 +1353,7 @@ CONFIG_SAMPLE_RUST_MISCDEV=m
 CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
+CONFIG_SAMPLE_RUST_SEQ_FILE=m
 # CONFIG_SAMPLE_RUST_RANDOM is not set
 # CONFIG_STRICT_DEVMEM is not set
 

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

@@ -1318,6 +1318,7 @@ CONFIG_SAMPLE_RUST_MISCDEV=m
 CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=m
+CONFIG_SAMPLE_RUST_SEQ_FILE=m
 # CONFIG_SAMPLE_RUST_RANDOM is not set
 # 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
@@ -1443,6 +1443,7 @@ CONFIG_SAMPLE_RUST_MISCDEV=m
 CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=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

@@ -1391,6 +1391,7 @@ CONFIG_SAMPLE_RUST_MISCDEV=m
 CONFIG_SAMPLE_RUST_STACK_PROBING=m
 CONFIG_SAMPLE_RUST_SEMAPHORE=m
 CONFIG_SAMPLE_RUST_SEMAPHORE_C=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

@@ -3,7 +3,9 @@
 #include <linux/cdev.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>
@@ -13,6 +15,10 @@
 #include <linux/mm.h>
 #include <uapi/linux/android/binder.h>
 
+#ifdef CONFIG_PROC_FS
+#include "../../fs/proc/internal.h"
+#endif
+
 // `bindgen` gets confused at certain things
 const gfp_t BINDINGS_GFP_KERNEL = GFP_KERNEL;
 const gfp_t BINDINGS___GFP_ZERO = __GFP_ZERO;

rust/kernel/lib.rs

@@ -52,7 +52,12 @@ pub mod module_param;
 
 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;
 

rust/kernel/proc_fs.rs

@@ -0,0 +1,82 @@
+// 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 alloc::boxed::Box;
+use core::{
+    marker::{PhantomData, Sync},
+    ops::Deref,
+    ptr,
+};
+
+use crate::{bindings, c_types, CStr, Error, KernelResult};
+
+/// An entry under `/proc` containing data of type `T`.
+///
+/// This is the Rust equivalent to [`proc_dir_entry`] on the C side.
+///
+/// # Invariants
+///
+/// The pointer [`ProcDirEntry::proc_dir_entry`] is a valid pointer and
+/// it's field [`bindings::proc_dir_entry::data`] is a valid pointer to
+/// `T`.
+///
+/// [`proc_dir_entry`]: ../../../fs/proc/internal.h
+pub struct ProcDirEntry<T> {
+    proc_dir_entry: *mut bindings::proc_dir_entry,
+    data: PhantomData<T>,
+}
+
+// SAFETY: The `proc_dir_entry` raw pointer isn't accessible.
+unsafe impl<T> Sync for ProcDirEntry<T> {}
+
+impl<T> Drop for ProcDirEntry<T> {
+    fn drop(&mut self) {
+        // SAFETY: `ProcDirEntry` is guaranteed to have a valid pointer to `T`
+        // in the `data` field of `proc_dir_entry`.
+        let data = unsafe { Box::from_raw((*self.proc_dir_entry).data as *mut T) };
+        // 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);
+        }
+        drop(data);
+    }
+}
+
+/// Create an entry in `/proc` containing data of type `T`.
+///
+/// Corresponds to [`proc_create_data`] on the C side.
+///
+/// [`proc_create_data]: ../../../fs/proc/generic.c
+pub(crate) fn proc_create_data<T>(
+    name: CStr<'static>,
+    proc_ops: &'static bindings::proc_ops,
+    data: T,
+) -> KernelResult<ProcDirEntry<T>> {
+    let data_ptr = Box::into_raw(Box::try_new(data)?) as *mut c_types::c_void;
+    let name = name.deref().as_ptr() as *const u8 as *const c_types::c_char;
+
+    // SAFETY: Calling a C function. `name` is guaranteed to be null terminated
+    // because it is of type `CStr`.
+    let proc_dir_entry =
+        unsafe { bindings::proc_create_data(name, 0, ptr::null_mut(), proc_ops, data_ptr) };
+    if proc_dir_entry.is_null() {
+        Err(Error::ENOMEM)
+    } else {
+        // INVARIANT: `proc_dir_entry` is a valid pointer and it's data field
+        // is a valid pointer to `T`.
+        Ok(ProcDirEntry {
+            proc_dir_entry,
+            data: PhantomData,
+        })
+    }
+}