build.rs: Build fixes for Centos 7

Cargo.toml

@@ -8,6 +8,6 @@ edition = "2018"
 bitflags = "1"
 
 [build-dependencies]
-bindgen = "0.54"
+bindgen = "0.56"
 cc = "1.0"
 shlex = "0.1"

build.rs

@@ -53,6 +53,14 @@ const OPAQUE_TYPES: &[&str] = &[
     // and https://github.com/rust-lang/rust-bindgen/issues/1538
     "desc_struct",
     "xregs_state",
+    "xsave_struct",
+];
+const CLANG_ARGS_BLACKLIST: [&'static str; 5] = [
+    "-maccumulate-outgoing-args",
+    "-mpreferred-stack-boundary=3",
+    "-mindirect-branch=thunk-extern",
+    "-mindirect-branch-register",
+    "-fconserve-stack",
 ];
 
 fn handle_kernel_version_cfg(bindings_path: &PathBuf) {
@@ -86,10 +94,15 @@ fn handle_kernel_version_cfg(bindings_path: &PathBuf) {
     }
     if major >= 4 {
         // We don't currently support anything older than 4.4
-        for x in 4..=if major > 4 { 20 } else { minor } {
+        for x in 1..=if major > 4 { 20 } else { minor } {
             println!("cargo:rustc-cfg=kernel_4_{}_0_or_greater", x);
         }
     }
+    if major >= 3 {
+        for x in 1..=if major > 3 { 19 } else { minor } {
+            println!("cargo:rustc-cfg=kernel_3_{}_0_or_greater", x);
+        }
+    }
 }
 
 fn handle_kernel_symbols_cfg(symvers_path: &PathBuf) {
@@ -153,6 +166,12 @@ fn main() {
 
     builder = builder.clang_arg(format!("--target={}", target));
     for arg in kernel_args.iter() {
+        if CLANG_ARGS_BLACKLIST.contains(&arg.as_str()) {
+            continue;
+        }
+        if arg.as_str() == "-DOS_CENTOS" {
+            println!("cargo:rustc-cfg=os_centos")
+        }
         builder = builder.clang_arg(arg.clone());
     }
 
@@ -182,13 +201,17 @@ fn main() {
     handle_kernel_symbols_cfg(&PathBuf::from(&kernel_dir).join("Module.symvers"));
 
     let mut builder = cc::Build::new();
-    builder.compiler(env::var("CC").unwrap_or_else(|_| "clang".to_string()));
+    let compiler = env::var("CC").unwrap_or_else(|_| "clang".to_string());
+    builder.compiler(&compiler);
     builder.target(&target);
     builder.warnings(false);
     println!("cargo:rerun-if-changed=src/helpers.c");
     builder.file("src/helpers.c");
     for arg in kernel_args.iter() {
         builder.flag(&arg);
     }
+    if &compiler == "gcc" {
+        builder.flag("-fno-pie");
+    }
     builder.compile("helpers");
 }

hello-world/Kbuild

@@ -6,7 +6,7 @@ CARGO ?= cargo
 export c_flags
 
 $(src)/target/x86_64-linux-kernel/debug/libhello_world.a: cargo_will_determine_dependencies
-	cd $(src); $(CARGO) build -Z build-std=core,alloc --target=x86_64-linux-kernel
+	cd $(src); $(CARGO) +nightly build -Z build-std=core,alloc --target=x86_64-linux-kernel
 
 .PHONY: cargo_will_determine_dependencies
 

hello-world/Makefile

@@ -1,12 +1,23 @@
 export KDIR ?= /lib/modules/$(shell uname -r)/build
 
+CONFIG_CC_IS_CLANG := y
 CLANG ?= clang
 ifeq ($(origin CC),default)
 CC := ${CLANG}
 endif
 
+HEADER_SEMVER ?= $(shell uname -r | grep -oG "[0-9]\+\.[0-9]\+\.[0-9]\+" | head -1)
+ifeq ($(shell echo $(HEADER_SEMVER) 4.4.0 | tr " " "\n" | sort -V | head -1), $(HEADER_SEMVER))
+CC := gcc
+CONFIG_CC_IS_CLANG := n
+endif
+
+ifneq (,$(wildcard /etc/centos-release))
+KCPPFLAGS += -DOS_CENTOS
+endif
+
 all:
-	$(MAKE) -C $(KDIR) M=$(CURDIR) CC=$(CC) CONFIG_CC_IS_CLANG=y
+	$(MAKE) -C $(KDIR) M=$(CURDIR) CC=$(CC) KCPPFLAGS=$(KCPPFLAGS) CONFIG_CC_IS_CLANG=$(CONFIG_CC_IS_CLANG)
 
 clean:
 	$(MAKE) -C $(KDIR) M=$(CURDIR) CC=$(CC) clean

src/file_operations.rs

@@ -159,19 +159,24 @@ impl<T: FileOperations> FileOperationsVtable<T> {
         } else {
             None
         },
-
+        #[cfg(not(kernel_4_1_0_or_greater))]
+        aio_read: None,
+        #[cfg(not(kernel_4_1_0_or_greater))]
+        aio_write: None,
+        #[cfg(not(kernel_3_11_0_or_greater))]
+        readdir: None,
         #[cfg(not(kernel_4_9_0_or_greater))]
         aio_fsync: None,
         check_flags: None,
-        #[cfg(all(kernel_4_5_0_or_greater, not(kernel_4_20_0_or_greater)))]
+        #[cfg(all(kernel_4_5_0_or_greater, not(kernel_4_20_0_or_greater), not(os_centos)))]
         clone_file_range: None,
         compat_ioctl: None,
         #[cfg(kernel_4_5_0_or_greater)]
         copy_file_range: None,
-        #[cfg(all(kernel_4_5_0_or_greater, not(kernel_4_20_0_or_greater)))]
+        #[cfg(all(kernel_4_5_0_or_greater, not(kernel_4_20_0_or_greater), not(os_centos)))]
         dedupe_file_range: None,
         fallocate: None,
-        #[cfg(kernel_4_19_0_or_greater)]
+        #[cfg(any(kernel_4_19_0_or_greater, all(os_centos, kernel_4_18_0_or_greater)))]
         fadvise: None,
         fasync: None,
         flock: None,
@@ -181,26 +186,40 @@ impl<T: FileOperations> FileOperationsVtable<T> {
         iterate: None,
         #[cfg(kernel_4_7_0_or_greater)]
         iterate_shared: None,
-        #[cfg(kernel_5_1_0_or_greater)]
+        #[cfg(any(kernel_5_1_0_or_greater, all(os_centos, kernel_4_18_0_or_greater)))]
         iopoll: None,
         lock: None,
         mmap: None,
         #[cfg(kernel_4_15_0_or_greater)]
         mmap_supported_flags: 0,
         owner: ptr::null_mut(),
         poll: None,
+        #[cfg(kernel_3_16_0_or_greater)]
         read_iter: None,
-        #[cfg(kernel_4_20_0_or_greater)]
+        #[cfg(any(kernel_4_20_0_or_greater, all(os_centos, kernel_4_18_0_or_greater)))]
         remap_file_range: None,
         sendpage: None,
         #[cfg(kernel_aufs_setfl)]
         setfl: None,
+        #[cfg(all(not(kernel_4_18_0_or_greater), os_centos))]
+        __bindgen_anon_1: bindings::file_operations__bindgen_ty_1 { setlease: None },
+        #[cfg(any(kernel_4_18_0_or_greater, not(os_centos)))]
         setlease: None,
         show_fdinfo: None,
         splice_read: None,
         splice_write: None,
         unlocked_ioctl: None,
+        #[cfg(kernel_3_16_0_or_greater)]
         write_iter: None,
+
+        #[cfg(all(os_centos, kernel_4_18_0_or_greater))]
+        rh_reserved1: 0,
+        #[cfg(all(os_centos, kernel_4_18_0_or_greater))]
+        rh_reserved2: 0,
+        #[cfg(all(os_centos, kernel_4_18_0_or_greater))]
+        rh_reserved3: 0,
+        #[cfg(all(os_centos, kernel_4_18_0_or_greater))]
+        rh_reserved4: 0,
     };
 }
 

src/helpers.c

@@ -3,15 +3,16 @@
 #include <linux/uaccess.h>
 #include <linux/version.h>
 
-
 void bug_helper(void)
 {
     BUG();
 }
 
 int access_ok_helper(const void __user *addr, unsigned long n)
 {
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 0, 0) /* v5.0-rc1~46 */
+#if defined(OS_CENTOS) && LINUX_VERSION_CODE >= KERNEL_VERSION(4, 18, 0)
+    return access_ok(addr, n);
+#elif LINUX_VERSION_CODE >= KERNEL_VERSION(5, 0, 0) /* v5.0-rc1~46 */
     return access_ok(addr, n);
 #else
     return access_ok(0, addr, n);