arch: add s390x support

.github/workflows/rust.yml

@@ -21,6 +21,7 @@ jobs:
           - aarch64-unknown-linux-gnu
           - riscv64gc-unknown-linux-gnu
           - loongarch64-unknown-linux-gnu
+          - s390x-unknown-linux-gnu
 
     steps:
     - name: "Checkout"

crates/asm/src/lib.rs

@@ -5,7 +5,8 @@
 //! What do you mean I wasted two whole hours to make the program only 100µs
 //! faster?
 //!
-//! Supports `x86_64`, `aarch64`, `riscv64`, and `loongarch64` architectures.
+//! Supports `x86_64`, `aarch64`, `riscv64`, `loongarch64`, and `s390x`
+//! architectures.
 
 #![no_std]
 
@@ -14,11 +15,12 @@
   target_arch = "x86_64",
   target_arch = "aarch64",
   target_arch = "riscv64",
-  target_arch = "loongarch64"
+  target_arch = "loongarch64",
+  target_arch = "s390x"
 )))]
 compile_error!(
-  "Unsupported architecture: only x86_64, aarch64, riscv64, and loongarch64 \
-   are supported"
+  "Unsupported architecture: only x86_64, aarch64, riscv64, loongarch64, and \
+   s390x are supported"
 );
 
 // Per-arch syscall implementations live in their own module files.
@@ -34,6 +36,9 @@ mod arch;
 #[cfg(target_arch = "loongarch64")]
 #[path = "loongarch64.rs"]
 mod arch;
+#[cfg(target_arch = "s390x")]
+#[path = "s390x.rs"]
+mod arch;
 
 /// Copies `n` bytes from `src` to `dest`.
 ///
@@ -267,6 +272,7 @@ pub unsafe fn sys_uname(buf: *mut UtsNameBuf) -> i32 {
 /// offsets on both architectures. Only the fields needed for disk usage are
 /// declared; the remainder of the 120-byte struct is covered by `_pad`.
 #[repr(C)]
+#[cfg(not(target_arch = "s390x"))]
 pub struct StatfsBuf {
   pub f_type:    i64,
   pub f_bsize:   i64,
@@ -284,6 +290,26 @@ pub struct StatfsBuf {
   pub _pad: [i64; 4],
 }
 
+/// on s390x `f_type` and `f_bsize` are 32-bit.
+#[repr(C)]
+#[cfg(target_arch = "s390x")]
+pub struct StatfsBuf {
+  pub f_type:    u32,
+  pub f_bsize:   u32,
+  pub f_blocks:  u64,
+  pub f_bfree:   u64,
+  pub f_bavail:  u64,
+  pub f_files:   u64,
+  pub f_ffree:   u64,
+  pub f_fsid:    [i32; 2],
+  pub f_namelen: u32,
+  pub f_frsize:  u32,
+  pub f_flags:   u32,
+
+  #[allow(clippy::pub_underscore_fields, reason = "This is not a public API")]
+  pub _pad: [u32; 5],
+}
+
 /// Direct `statfs(2)` syscall
 ///
 /// # Returns

crates/asm/src/s390x.rs

@@ -0,0 +1,160 @@
+//! Syscall implementations for `s390x`.
+
+use super::{StatfsBuf, SysInfo, UtsNameBuf};
+
+pub(super) unsafe fn sys_open(path: *const u8, flags: i32) -> i32 {
+  unsafe {
+    let fd: i64;
+    core::arch::asm!(
+      "svc 0",
+      in("r1") 5i64,  // SYS_open
+      in("r2") path,
+      in("r3") flags,
+      in("r4") 0i32,  // mode
+      lateout("r2") fd,
+      options(nostack)
+    );
+    #[allow(clippy::cast_possible_truncation)]
+    {
+      fd as i32
+    }
+  }
+}
+
+pub(super) unsafe fn sys_read(fd: i32, buf: *mut u8, count: usize) -> isize {
+  unsafe {
+    let ret: i64;
+    core::arch::asm!(
+      "svc 0",
+      in("r1") 3i64,  // SYS_read
+      in("r2") fd,
+      in("r3") buf,
+      in("r4") count,
+      lateout("r2") ret,
+      options(nostack)
+    );
+    #[allow(clippy::cast_possible_truncation)]
+    {
+      ret as isize
+    }
+  }
+}
+
+pub(super) unsafe fn sys_write(fd: i32, buf: *const u8, count: usize) -> isize {
+  unsafe {
+    let ret: i64;
+    core::arch::asm!(
+      "svc 0",
+      in("r1") 4i64,  // SYS_write
+      in("r2") fd,
+      in("r3") buf,
+      in("r4") count,
+      lateout("r2") ret,
+      options(nostack)
+    );
+    #[allow(clippy::cast_possible_truncation)]
+    {
+      ret as isize
+    }
+  }
+}
+
+pub(super) unsafe fn sys_close(fd: i32) -> i32 {
+  unsafe {
+    let ret: i64;
+    core::arch::asm!(
+      "svc 0",
+      in("r1") 6i64,  // SYS_close
+      in("r2") fd,
+      lateout("r2") ret,
+      options(nostack)
+    );
+    #[allow(clippy::cast_possible_truncation)]
+    {
+      ret as i32
+    }
+  }
+}
+
+pub(super) unsafe fn sys_uname(buf: *mut UtsNameBuf) -> i32 {
+  unsafe {
+    let ret: i64;
+    core::arch::asm!(
+      "svc 0",
+      in("r1") 122i64,  // SYS_uname
+      in("r2") buf,
+      lateout("r2") ret,
+      options(nostack)
+    );
+    #[allow(clippy::cast_possible_truncation)]
+    {
+      ret as i32
+    }
+  }
+}
+
+pub(super) unsafe fn sys_statfs(path: *const u8, buf: *mut StatfsBuf) -> i32 {
+  unsafe {
+    let ret: i64;
+    core::arch::asm!(
+      "svc 0",
+      in("r1") 99i64,  // SYS_statfs
+      in("r2") path,
+      in("r3") buf,
+      lateout("r2") ret,
+      options(nostack)
+    );
+    #[allow(clippy::cast_possible_truncation)]
+    {
+      ret as i32
+    }
+  }
+}
+
+pub(super) unsafe fn sys_sysinfo(info: *mut SysInfo) -> i64 {
+  unsafe {
+    let ret: i64;
+    core::arch::asm!(
+      "svc 0",
+      in("r1") 116_i64, // __NR_sysinfo
+      in("r2") info,
+      lateout("r2") ret,
+      options(nostack)
+    );
+    ret
+  }
+}
+
+pub(super) unsafe fn sys_sched_getaffinity(
+  pid: i32,
+  mask_size: usize,
+  mask: *mut u8,
+) -> i32 {
+  unsafe {
+    let ret: i64;
+    core::arch::asm!(
+      "svc 0",
+      in("r1") 240i64,  // __NR_sched_getaffinity
+      in("r2") pid,
+      in("r3") mask_size,
+      in("r4") mask,
+      lateout("r2") ret,
+      options(nostack)
+    );
+    #[allow(clippy::cast_possible_truncation)]
+    {
+      ret as i32
+    }
+  }
+}
+
+pub(super) unsafe fn sys_exit(code: i32) -> ! {
+  unsafe {
+    core::arch::asm!(
+      "svc 0",
+      in("r1") 1i64,  // SYS_exit
+      in("r2") code,
+      options(noreturn, nostack)
+    );
+  }
+}

crates/lib/src/cpu.rs

@@ -140,10 +140,15 @@ fn get_cpu_freq_mhz() -> Option<u32> {
     }
   }
   // Fall back to cpuinfo fields
-  let mut buf2 = [0u8; 2048];
+  let mut buf2 = [0u8; 4096];
   let n = read_file_fast("/proc/cpuinfo", &mut buf2).ok()?;
   let data = &buf2[..n];
-  for key in &[b"cpu MHz" as &[u8], b"cpu MHz dynamic", b"CPU MHz"] {
+  for key in &[
+    b"cpu MHz" as &[u8],
+    b"cpu MHz dynamic",
+    b"cpu MHz static",
+    b"CPU MHz",
+  ] {
     if let Some(val) = extract_field(data, key) {
       // Parse integer part of the MHz value (e.g. "5200.00" -> 5200)
       let mut mhz = 0u32;

microfetch/src/main.rs

@@ -72,6 +72,22 @@ unsafe extern "C" fn _start() {
   );
 }
 
+#[cfg(target_arch = "s390x")]
+#[unsafe(no_mangle)]
+#[unsafe(naked)]
+unsafe extern "C" fn _start() {
+  naked_asm!(
+    "lgr %r2, %r15",       // save original sp (argc/argv) as arg
+    "aghi %r15, -160",     // allocate s390x mandatory stack frame
+    "lghi %r0, -16",
+    "ngr %r15, %r0",       // align stack to 16 bytes
+    "brasl %r14, {entry_rust}",
+    "lghi %r1, 1",         // SYS_exit
+    "svc 0",
+    entry_rust = sym entry_rust,
+  );
+}
+
 // Global allocator
 #[global_allocator]
 static ALLOCATOR: BumpAllocator = BumpAllocator::new();