Add m68k architecture support

Author: pekkarr

gen/include/support.h

@@ -10,8 +10,24 @@ typedef __INT8_TYPE__ int8_t;
 typedef __INT16_TYPE__ int16_t;
 typedef __INT32_TYPE__ int32_t;
 typedef __INT64_TYPE__ int64_t;
+#ifdef __m68k__
+// Hack: until the fix for [1] is released, lie to clang that `size_t` has
+// alignment 4 on m68k. This doesn't affect the correctness of bindings, since
+// the only structs that (transitively) contain a size_t are
+// `net::{msghdr, cmsghdr, mmsghdr}` and their definitions are the same
+// regardless of the alignment of `size_t`.
+//
+// [1]: https://github.com/rust-lang/rust-bindgen/issues/3312
+typedef struct __attribute__((aligned(4))) {
+  __SIZE_TYPE__ s;
+} size_t;
+typedef struct __attribute__((aligned(4))) {
+  __PTRDIFF_TYPE__ s;
+} ssize_t;
+#else
 typedef __SIZE_TYPE__ size_t;
 typedef __PTRDIFF_TYPE__ ssize_t;
+#endif
 typedef __PTRDIFF_TYPE__ ptrdiff_t;
 typedef __INTPTR_TYPE__ intptr_t;
 typedef __UINTPTR_TYPE__ uintptr_t;

gen/ioctl/generate.sh

@@ -105,5 +105,10 @@ cat loongarch-ioctls.txt >> "$out"
 # qemu-csky -L /usr/csky-linux-gnuabiv2 ./main.exe >> "$out"
 cat csky-ioctls.txt >> "$out"
 
+install_headers m68k
+m68k-linux-gnu-gcc "${includes[@]}" -c list.c $cflags
+m68k-linux-gnu-gcc main.c list.o -o main.exe $cflags
+qemu-m68k -L /usr/m68k-linux-gnu ./main.exe >> "$out"
+
 # Add any extra custom definitions at the end.
 echo "#include \"ioctl-addendum.h\"" >> "$out"

gen/ioctl/list.c

@@ -100,7 +100,7 @@ struct sockaddr {
 #include <linux/joystick.h>
 #include <linux/kd.h>
 #include <linux/kcov.h>
-#if !defined(__arm__) && !defined(__loongarch__) && !defined(__powerpc64__) && !defined(__riscv) && !defined(__csky__)// various errors
+#if !defined(__arm__) && !defined(__loongarch__) && !defined(__powerpc64__) && !defined(__riscv) && !defined(__csky__) && !defined(__m68k__) // various errors
 #include <linux/kvm.h>
 #endif
 #include <linux/lirc.h>

gen/ioctl/main.c

@@ -49,6 +49,8 @@ int main(void) {
     printf("#ifdef __loongarch__\n");
 #elif defined(__csky__)
     printf("#ifdef __csky__\n");
+#elif defined(__m68k__)
+    printf("#ifdef __m68k__\n");
 #else
 #error "unimplemented architecture"
 #endif

gen/modules/general.h

@@ -229,7 +229,7 @@ struct user_desc {
 // that its fourth argument be the size of the kernel's internal `sigset_t`
 // type. So we define our own.
 
-#if defined(__i386__) || defined(__x86_64__) || defined(__s390x__) || defined(__arm__) || defined(__loongarch__)
+#if defined(__i386__) || defined(__x86_64__) || defined(__s390x__) || defined(__arm__) || defined(__loongarch__) || defined(__m68k__)
 #define _NSIG 64
 #endif
 

gen/src/main.rs

@@ -174,11 +174,7 @@ fn main() {
     writeln!(cargo_toml, "std = []").unwrap();
     writeln!(cargo_toml, "no_std = []").unwrap();
     writeln!(cargo_toml, "elf = []").unwrap();
-    writeln!(
-        cargo_toml,
-        "rustc-dep-of-std = [\"core\", \"no_std\"]"
-    )
-    .unwrap();
+    writeln!(cargo_toml, "rustc-dep-of-std = [\"core\", \"no_std\"]").unwrap();
 
     eprintln!("All bindings generated!");
 }
@@ -291,15 +287,16 @@ fn rust_arches(linux_arch: &str) -> &[&str] {
         "csky" => &["csky"],
         "hexagon" => &["hexagon"],
         "loongarch" => &["loongarch64"],
+        "m68k" => &["m68k"],
         "mips" => &["mips", "mips64", "mips32r6", "mips64r6"],
         "powerpc" => &["powerpc", "powerpc64"],
         "riscv" => &["riscv32", "riscv64"],
         "s390" => &["s390x"],
         "sparc" => &["sparc", "sparc64"],
         "x86" => &["x86", "x86_64", "x32"],
-        "alpha" | "cris" | "h8300" | "m68k" | "microblaze" | "mn10300" | "score" | "blackfin"
-        | "frv" | "ia64" | "m32r" | "m68knommu" | "parisc" | "sh" | "um" | "xtensa"
-        | "unicore32" | "c6x" | "nios2" | "openrisc" | "arc" | "nds32" | "metag" | "tile" => &[],
+        "alpha" | "cris" | "h8300" | "microblaze" | "mn10300" | "score" | "blackfin" | "frv"
+        | "ia64" | "m32r" | "m68knommu" | "parisc" | "sh" | "um" | "xtensa" | "unicore32"
+        | "c6x" | "nios2" | "openrisc" | "arc" | "nds32" | "metag" | "tile" => &[],
         _ => panic!("unrecognized arch: {}", linux_arch),
     }
 }
@@ -362,6 +359,13 @@ fn run_bindgen(
         builder = builder.blocklist_item("^HUGETLB_FLAG_ENCODE_.*");
         builder = builder.blocklist_item("^RESOLVE_.*");
     }
+    if rust_arch == "m68k" {
+        // Don't emit the `size_t` workaround types for m68k. This should be
+        // removed when there's a bindgen release with a fix for [1].
+        //
+        // [1]: https://github.com/rust-lang/rust-bindgen/issues/3312
+        builder = builder.blocklist_type("^s?size_t$");
+    }
 
     let bindings = builder
         .use_core()

src/lib.rs

@@ -27,6 +27,7 @@ pub mod ctypes {
     pub type c_char = c_uchar;
     #[cfg(any(
         target_arch = "loongarch64",
+        target_arch = "m68k",
         target_arch = "mips",
         target_arch = "mips64",
         target_arch = "mips32r6",