Add syscall rt_sigsuspend

docs/src/kernel/linux-compatibility.md

@@ -150,7 +150,7 @@ provided by Linux on x86-64 architecture.
 | 127     | rt_sigpending    | ❌              |
 | 128     | rt_sigtimedwait  | ❌              |
 | 129     | rt_sigqueueinfo  | ❌              |
-| 130     | rt_sigsuspend    | ❌              |
+| 130     | rt_sigsuspend    | ✅              |
 | 131     | sigaltstack      | ✅              |
 | 132     | utime            | ❌              |
 | 133     | mknod            | ❌              |

kernel/aster-nix/src/process/signal/sig_mask.rs

@@ -1,8 +1,10 @@
 // SPDX-License-Identifier: MPL-2.0
 
 use super::{constants::MIN_STD_SIG_NUM, sig_num::SigNum};
+use crate::prelude::*;
 
-#[derive(Debug, Copy, Clone, Default, PartialEq, Eq)]
+#[derive(Debug, Copy, Clone, Default, PartialEq, Eq, Pod)]
+#[repr(C)]
 pub struct SigMask {
     bits: u64,
 }

kernel/aster-nix/src/syscall/mod.rs

@@ -22,6 +22,7 @@ use self::{
     listen::sys_listen,
     pread64::sys_pread64,
     recvfrom::sys_recvfrom,
+    rt_sigsuspend::sys_rt_sigsuspend,
     sendto::sys_sendto,
     setfsgid::sys_setfsgid,
     setfsuid::sys_setfsuid,
@@ -191,6 +192,7 @@ mod rmdir;
 mod rt_sigaction;
 mod rt_sigprocmask;
 mod rt_sigreturn;
+mod rt_sigsuspend;
 mod sched_yield;
 mod select;
 mod sendto;
@@ -352,6 +354,7 @@ define_syscall_nums!(
     SYS_SETFSUID = 122,
     SYS_SETFSGID = 123,
     SYS_GETSID = 124,
+    SYS_RT_SIGSUSPEND = 130,
     SYS_SIGALTSTACK = 131,
     SYS_STATFS = 137,
     SYS_FSTATFS = 138,
@@ -544,6 +547,7 @@ pub fn syscall_dispatch(
         SYS_SETFSUID => syscall_handler!(1, sys_setfsuid, args),
         SYS_SETFSGID => syscall_handler!(1, sys_setfsgid, args),
         SYS_GETSID => syscall_handler!(1, sys_getsid, args),
+        SYS_RT_SIGSUSPEND => syscall_handler!(2, sys_rt_sigsuspend, args),
         SYS_SIGALTSTACK => syscall_handler!(2, sys_sigaltstack, args),
         SYS_STATFS => syscall_handler!(2, sys_statfs, args),
         SYS_FSTATFS => syscall_handler!(2, sys_fstatfs, args),

kernel/aster-nix/src/syscall/rt_sigsuspend.rs

@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use super::{SyscallReturn, SYS_RT_SIGSUSPEND};
+use crate::{
+    log_syscall_entry,
+    prelude::*,
+    process::signal::{
+        constants::{SIGKILL, SIGSTOP},
+        sig_mask::SigMask,
+        Pauser,
+    },
+    util::read_val_from_user,
+};
+
+pub fn sys_rt_sigsuspend(sigmask_addr: Vaddr, sigmask_size: usize) -> Result<SyscallReturn> {
+    log_syscall_entry!(SYS_RT_SIGSUSPEND);
+    debug!(
+        "sigmask_addr = 0x{:x}, sigmask_size = {}",
+        sigmask_addr, sigmask_size
+    );
+
+    debug_assert!(sigmask_size == core::mem::size_of::<SigMask>());
+    if sigmask_size != core::mem::size_of::<SigMask>() {
+        return_errno_with_message!(Errno::EINVAL, "invalid sigmask size");
+    }
+
+    let sigmask = {
+        let mut mask: SigMask = read_val_from_user(sigmask_addr)?;
+        // It is not possible to block SIGKILL or SIGSTOP,
+        // specifying these signals in mask has no effect.
+        mask.remove_signal(SIGKILL);
+        mask.remove_signal(SIGSTOP);
+        mask
+    };
+
+    // Pause until receiving any signal
+    let pauser = Pauser::new_with_mask(sigmask);
+    pauser.pause_until(|| None::<()>)?;
+
+    // This syscall should always return `Err(EINTR)`. This path should never be reached.
+    unreachable!("rt_sigsuspend always return EINTR");
+}