Merge pull request #87 from adamrk/rust-int-params

Add Rust int param types

Author: ojeda

.github/workflows/ci.yaml

@@ -156,7 +156,7 @@ jobs:
       # Run
       - run: ${{ env.BUILD_DIR }}usr/gen_init_cpio .github/workflows/qemu-initramfs.desc > qemu-initramfs.img
 
-      - run: qemu-system-${{ env.QEMU_ARCH }} -kernel ${{ env.BUILD_DIR }}${{ env.IMAGE_PATH }} -initrd qemu-initramfs.img -M ${{ env.QEMU_MACHINE }} -cpu ${{ env.QEMU_CPU }} -smp 2 -nographic -no-reboot -append '${{ env.QEMU_APPEND }} rust_example.my_i32=123321 rust_example.my_str=🦀mod rust_example.my_invbool=y rust_example_2.my_i32=234432' | tee qemu-stdout.log
+      - run: qemu-system-${{ env.QEMU_ARCH }} -kernel ${{ env.BUILD_DIR }}${{ env.IMAGE_PATH }} -initrd qemu-initramfs.img -M ${{ env.QEMU_MACHINE }} -cpu ${{ env.QEMU_CPU }} -smp 2 -nographic -no-reboot -append '${{ env.QEMU_APPEND }} rust_example.my_i32=123321 rust_example.my_str=🦀mod rust_example_2.my_i32=234432' | tee qemu-stdout.log
 
       # Check
       - run: grep -F     '] Rust Example (init)' qemu-stdout.log
@@ -169,6 +169,11 @@ jobs:
       - run: "grep -F '] [3]   my_i32:     345543' qemu-stdout.log"
       - run: "grep -F '] [4]   my_i32:     456654' qemu-stdout.log"
 
+      - run: "grep -F     ']   my_usize:   42' qemu-stdout.log"
+      - run: "grep -F '] [2]   my_usize:   42' qemu-stdout.log"
+      - run: "grep -F '] [3]   my_usize:   42' qemu-stdout.log"
+      - run: "grep -F '] [4]   my_usize:   84' qemu-stdout.log"
+
       - run: "grep            '\\]   my_str:     🦀mod\\s*$'           qemu-stdout.log"
       - run: "grep    '\\] \\[2\\]   my_str:     default str val\\s*$' qemu-stdout.log"
       - run: "grep    '\\] \\[3\\]   my_str:     🦀mod\\s*$'           qemu-stdout.log"

.github/workflows/qemu-init.sh

@@ -1,7 +1,7 @@
 #!/bin/sh
 
 busybox insmod rust_example_3.ko my_i32=345543 my_str=🦀mod
-busybox insmod rust_example_4.ko my_i32=456654
+busybox insmod rust_example_4.ko my_i32=456654 my_usize=84
 busybox  rmmod rust_example_3.ko
 busybox  rmmod rust_example_4.ko
 

drivers/char/rust_example.rs

@@ -33,6 +33,11 @@ module! {
             permissions: 0o644,
             description: b"Example of a string param",
         },
+        my_usize: usize {
+            default: 42,
+            permissions: 0o644,
+            description: b"Example of usize",
+        },
     },
 }
 
@@ -66,6 +71,7 @@ impl KernelModule for RustExample {
                 "  my_str:     {}",
                 core::str::from_utf8(my_str.read(&lock))?
             );
+            println!("  my_usize:   {}", my_usize.read(&lock));
         }
 
         // Including this large variable on the stack will trigger

drivers/char/rust_example_2.rs

@@ -28,6 +28,11 @@ module! {
             permissions: 0o644,
             description: b"Example of a string param",
         },
+        my_usize: usize {
+            default: 42,
+            permissions: 0o644,
+            description: b"Example of usize",
+        },
     },
 }
 
@@ -48,6 +53,7 @@ impl KernelModule for RustExample2 {
                 "[2]   my_str:     {}",
                 core::str::from_utf8(my_str.read(&lock))?
             );
+            println!("[2]   my_usize:   {}", my_usize.read(&lock));
         }
 
         // Including this large variable on the stack will trigger

drivers/char/rust_example_3.rs

@@ -28,6 +28,11 @@ module! {
             permissions: 0o644,
             description: b"Example of a string param",
         },
+        my_usize: usize {
+            default: 42,
+            permissions: 0o644,
+            description: b"Example of usize",
+        },
     },
 }
 
@@ -48,6 +53,7 @@ impl KernelModule for RustExample3 {
                 "[3]   my_str:     {}",
                 core::str::from_utf8(my_str.read(&lock))?
             );
+            println!("[3]   my_usize:   {}", my_usize.read(&lock));
         }
 
         // Including this large variable on the stack will trigger

drivers/char/rust_example_4.rs

@@ -28,6 +28,11 @@ module! {
             permissions: 0o644,
             description: b"Example of a string param",
         },
+        my_usize: usize {
+            default: 42,
+            permissions: 0o644,
+            description: b"Example of usize",
+        },
     },
 }
 
@@ -48,6 +53,7 @@ impl KernelModule for RustExample4 {
                 "[4]   my_str:     {}",
                 core::str::from_utf8(my_str.read(&lock))?
             );
+            println!("[4]   my_usize:   {}", my_usize.read(&lock));
         }
 
         // Including this large variable on the stack will trigger

rust/Makefile

@@ -72,7 +72,7 @@ $(objtree)/rust/bindings_generated.rs: $(srctree)/rust/kernel/bindings_helper.h
 quiet_cmd_exports = EXPORTS $@
       cmd_exports = \
 	$(NM) -p --defined-only $< \
-		| grep -F ' T ' | cut -d ' ' -f 3 | grep -E '^(__rust_|_R)' \
+		| grep -E ' (T|R) ' | cut -d ' ' -f 3 | grep -E '^(__rust_|_R)' \
 		| xargs -n1 -Isymbol \
 		echo 'EXPORT_SYMBOL$(exports_target_type)(symbol);' > $@
 

rust/kernel/buffer.rs

@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Struct for writing to a pre-allocated buffer with the [`write!`] macro.
+
+use core::fmt;
+
+/// A pre-allocated buffer that implements [`core::fmt::Write`].
+///
+/// Consequtive writes will append to what has already been written.
+/// Writes that don't fit in the buffer will fail.
+pub struct Buffer<'a> {
+    slice: &'a mut [u8],
+    pos: usize,
+}
+
+impl<'a> Buffer<'a> {
+    /// Create a new buffer from an existing array.
+    pub fn new(slice: &'a mut [u8]) -> Self {
+        Buffer { slice, pos: 0 }
+    }
+
+    /// Number of bytes that have already been written to the buffer.
+    /// This will always be less than the length of the original array.
+    pub fn bytes_written(&self) -> usize {
+        self.pos
+    }
+}
+
+impl<'a> fmt::Write for Buffer<'a> {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        if s.len() > self.slice.len() - self.pos {
+            Err(fmt::Error)
+        } else {
+            self.slice[self.pos..self.pos + s.len()].copy_from_slice(s.as_bytes());
+            self.pos += s.len();
+            Ok(())
+        }
+    }
+}

rust/kernel/lib.rs

@@ -30,11 +30,13 @@ mod allocator;
 #[doc(hidden)]
 pub mod bindings;
 
+pub mod buffer;
 pub mod c_types;
 pub mod chrdev;
 mod error;
 pub mod file_operations;
 pub mod miscdev;
+pub mod module_param;
 pub mod prelude;
 pub mod printk;
 pub mod random;
@@ -48,6 +50,11 @@ pub mod user_ptr;
 pub use crate::error::{Error, KernelResult};
 pub use crate::types::{CStr, Mode};
 
+/// Page size defined in terms of the `PAGE_SHIFT` macro from C.
+///
+/// [`PAGE_SHIFT`]: ../../../include/asm-generic/page.h
+pub const PAGE_SIZE: usize = 1 << bindings::PAGE_SHIFT;
+
 /// The top level entrypoint to implementing a kernel module.
 ///
 /// For any teardown or cleanup operations, your type may implement [`Drop`].