diff --git a/os/src/syscall/mod.rs b/os/src/syscall/mod.rs
index 0db1ed47..5cfe5cc5 100644
--- a/os/src/syscall/mod.rs
+++ b/os/src/syscall/mod.rs
@@ -35,7 +35,7 @@ pub fn syscall(syscall_id: usize, args: [usize; 3]) -> isize {
         SYSCALL_EXIT => sys_exit(args[0] as i32),
         SYSCALL_YIELD => sys_yield(),
         SYSCALL_KILL => sys_kill(args[0], args[1] as u32),
-        SYSCALL_SIGACTION => sys_sigaction(args[0] as u32, args[1] as *const SignalAction, args[2] as *mut SignalAction),
+        SYSCALL_SIGACTION => sys_sigaction(args[0], args[1] as *const SignalAction, args[2] as *mut SignalAction),
         SYSCALL_SIGPROCMASK => sys_sigprocmask(args[0] as u32),
         SYSCALL_SIGRETURN => sys_sigretrun(),
         SYSCALL_GET_TIME => sys_get_time(),
diff --git a/os/src/syscall/process.rs b/os/src/syscall/process.rs
index 351f7df1..ed6e1551 100644
--- a/os/src/syscall/process.rs
+++ b/os/src/syscall/process.rs
@@ -2,7 +2,7 @@ use crate::fs::{open_file, OpenFlags};
 use crate::mm::{translated_ref, translated_refmut, translated_str};
 use crate::task::{
     add_task, current_task, current_user_token, exit_current_and_run_next, pid2task,
-    suspend_current_and_run_next, SignalFlags, SignalAction,
+    suspend_current_and_run_next, SignalFlags, SignalAction, MAX_SIG,
 };
 use crate::timer::get_time_ms;
 use alloc::string::String;
@@ -159,15 +159,18 @@ fn check_sigaction_error(signal: SignalFlags, action: usize, old_action: usize)
     }
 }
 
-pub fn sys_sigaction(signal: u32, action: *const SignalAction, old_action: *mut SignalAction) -> isize {
+pub fn sys_sigaction(signum: usize, action: *const SignalAction, old_action: *mut SignalAction) -> isize {
     let token = current_user_token();
     if let Some(task) = current_task() {
         let mut inner = task.inner_exclusive_access();
-        if let Some(flag) = SignalFlags::from_bits(signal) {
+        if signum as usize > MAX_SIG {
+            return -1;
+        }
+        if let Some(flag) = SignalFlags::from_bits(1 << signum) {
             if check_sigaction_error(flag, action as usize, old_action as usize) {
                 return -1;
             }
-            let old_kernel_action = inner.signal_actions.table[signal as usize];
+            let old_kernel_action = inner.signal_actions.table[signum];
             if old_kernel_action.mask != SignalFlags::from_bits(40).unwrap() {
                 *translated_refmut(token, old_action) = old_kernel_action;
             } else {
@@ -175,7 +178,7 @@ pub fn sys_sigaction(signal: u32, action: *const SignalAction, old_action: *mut
                 ref_old_action.handler = old_kernel_action.handler;
             }
             let ref_action = translated_ref(token, action);
-            inner.signal_actions.table[signal as usize] = *ref_action;
+            inner.signal_actions.table[signum] = *ref_action;
             return 0;
         }
     }
diff --git a/user/src/bin/sig_tests.rs b/user/src/bin/sig_tests.rs
new file mode 100644
index 00000000..7f566dc0
--- /dev/null
+++ b/user/src/bin/sig_tests.rs
@@ -0,0 +1,158 @@
+#![no_std]
+#![no_main]
+
+#[macro_use]
+extern crate user_lib;
+
+use user_lib::{sigaction, sigprocmask, SignalAction, SignalFlags, fork, exit, wait, kill, getpid, sleep};
+
+fn func() {
+    println!("user_sig_test succsess");
+}
+
+fn user_sig_test_failsignum() {
+    let mut new = SignalAction::default();
+    let old = SignalAction::default();
+    new.handler = func as usize;
+    if sigaction(50, &new, &old) >= 0 {
+        panic!("Wrong sigaction but success!");
+    }
+}
+
+fn user_sig_test_kill() {
+    let mut new = SignalAction::default();
+    let old = SignalAction::default();
+    new.handler = func as usize;
+
+    if sigaction(10, &new, &old) < 0 {
+        panic!("Sigaction failed!");
+    }
+    if kill(getpid() as usize, 1 << 10) < 0 {
+        println!("Kill failed!");
+        exit(1);
+    }
+}
+
+fn user_sig_test_multiprocsignals() {
+    let pid= fork();
+    if pid == 0{
+        let mut new = SignalAction::default();
+        let old = SignalAction::default();
+        new.handler = func as usize;
+        if sigaction(10, &new, &old) < 0 {
+            panic!("Sigaction failed!");
+        }
+    } else {
+        if kill(pid as usize, 1 << 10) < 0 {
+            println!("Kill failed!");
+            exit(1);
+        }
+        let mut exit_code = 0;
+        wait(&mut exit_code);
+    }
+}
+
+fn user_sig_test_restore() {
+    let mut new = SignalAction::default();
+    let old = SignalAction::default();
+    let old2 = SignalAction::default();
+    new.handler = func as usize;
+
+    if sigaction(10, &new, &old) < 0 {
+        panic!("Sigaction failed!");
+    }
+
+    if sigaction(10, &old, &old2) < 0 {
+        panic!("Sigaction failed!");
+    }
+
+    if old2.handler != new.handler {
+        println!("Restore failed!");
+        exit(-1);
+    }
+}
+
+fn kernel_sig_test_ignore() {
+    sigprocmask(SignalFlags::SIGSTOP.bits() as u32);
+    if kill(getpid() as usize, SignalFlags::SIGSTOP.bits()) < 0{
+        println!("kill faild\n");
+        exit(-1);
+    }
+}
+
+fn kernel_sig_test_stop_cont() {
+    let pid= fork();
+    if pid == 0 {
+        kill(getpid() as usize, SignalFlags::SIGSTOP.bits());
+        sleep(1000);
+        exit(-1);
+    } else {
+        sleep(5000);
+        kill(pid as usize, SignalFlags::SIGCONT.bits());
+        let mut exit_code = 0;
+        wait(&mut exit_code);
+    }
+}
+
+fn kernel_sig_test_failignorekill() {
+    let mut new = SignalAction::default();
+    let old = SignalAction::default();
+    new.handler = func as usize;
+
+    if sigaction(9, &new, &old) >= 0 {
+        panic!("Should not set sigaction to kill!");
+    }
+
+    if sigaction(9, &new, 0 as *const SignalAction) >= 0 {
+        panic!("Should not set sigaction to kill!");
+    }
+
+    if sigaction(9, 0 as *const SignalAction, &old) >= 0 {
+        panic!("Should not set sigaction to kill!");
+    }
+}
+
+
+fn run(f: fn()) -> bool {
+    let pid = fork();
+    if pid == 0 {
+        f();
+        exit(0);
+    } else {
+        let mut exit_code: i32 = 0;
+        wait(&mut exit_code);
+        if exit_code != 0 {
+            println!("FAILED!");
+        } else {
+            println!("OK!");
+        }
+        exit_code == 0
+    }
+}
+
+#[no_mangle]
+pub fn main() -> i32 {
+    let tests: [(fn(), &str); 7] = [
+        (user_sig_test_failsignum, "user_sig_test_failsignum"),
+        (user_sig_test_kill, "user_sig_test_kill"),
+        (user_sig_test_multiprocsignals, "user_sig_test_multiprocsignals"),
+        (user_sig_test_restore, "user_sig_test_restore"),
+        (kernel_sig_test_ignore, "kernel_sig_test_ignore"),
+        (kernel_sig_test_stop_cont, "kernel_sig_test_stop_cont"),
+        (kernel_sig_test_failignorekill, "kernel_sig_test_failignorekill")
+    ];
+    let mut fail_num = 0;
+    for test in tests {
+        println!("Testing {}", test.1);
+        if !run(test.0) {
+            fail_num += 1;
+        }
+    }
+    if fail_num == 0 {
+        println!("ALL TESTS PASSED");
+        0
+    } else {
+        println!("SOME TESTS FAILED");
+        -1
+    }
+}
diff --git a/user/src/lib.rs b/user/src/lib.rs
index f15d9ce7..a17fbcc3 100644
--- a/user/src/lib.rs
+++ b/user/src/lib.rs
@@ -139,16 +139,68 @@ pub fn sleep(period_ms: usize) {
     }
 }
 
+/// Action for a signal
+#[repr(C)]
+#[derive(Debug, Clone, Copy)]
+pub struct SignalAction {
+    pub handler: usize, 
+    pub mask: SignalFlags
+}
+
+impl Default for SignalAction {
+    fn default() -> Self {
+        Self {
+            handler: 0,
+            mask: SignalFlags::empty()
+        }
+    }
+}
+
 bitflags! {
     pub struct SignalFlags: i32 {
-        const SIGINT    = 1 << 2;
-        const SIGILL    = 1 << 4;
-        const SIGABRT   = 1 << 6;
-        const SIGFPE    = 1 << 8;
-        const SIGSEGV   = 1 << 11;
+        const SIGDEF = 1; // Default signal handling
+        const SIGHUP = 1 << 1;
+        const SIGINT = 1 << 2;
+        const SIGQUIT = 1 << 3;
+        const SIGILL = 1 << 4;
+        const SIGTRAP = 1 << 5;
+        const SIGABRT = 1 << 6;
+        const SIGBUS = 1 << 7;
+        const SIGFPE = 1 << 8;
+        const SIGKILL = 1 << 9;
+        const SIGUSR1 = 1 << 10;
+        const SIGSEGV = 1 << 11;
+        const SIGUSR2 = 1 << 12;
+        const SIGPIPE = 1 << 13;
+        const SIGALRM = 1 << 14;
+        const SIGTERM = 1 << 15;
+        const SIGSTKFLT = 1 << 16;
+        const SIGCHLD = 1 << 17;
+        const SIGCONT = 1 << 18;
+        const SIGSTOP = 1 << 19;
+        const SIGTSTP = 1 << 20;
+        const SIGTTIN = 1 << 21;
+        const SIGTTOU = 1 << 22;
+        const SIGURG = 1 << 23;
+        const SIGXCPU = 1 << 24;
+        const SIGXFSZ = 1 << 25;
+        const SIGVTALRM = 1 << 26;
+        const SIGPROF = 1 << 27;
+        const SIGWINCH = 1 << 28;
+        const SIGIO = 1 << 29;
+        const SIGPWR = 1 << 30;
+        const SIGSYS = 1 << 31;
     }
 }
 
 pub fn kill(pid: usize, signal: i32) -> isize {
     sys_kill(pid, signal)
 }
+
+pub fn sigaction(signum: usize, action: *const SignalAction, old_action: *const SignalAction) -> isize {
+    sys_sigaction(signum, action, old_action)
+}
+
+pub fn sigprocmask(mask: u32) -> isize {
+    sys_sigprocmask(mask)
+}
diff --git a/user/src/syscall.rs b/user/src/syscall.rs
index 1481de68..ea5c2014 100644
--- a/user/src/syscall.rs
+++ b/user/src/syscall.rs
@@ -1,5 +1,7 @@
 use core::arch::asm;
 
+use crate::SignalAction;
+
 const SYSCALL_DUP: usize = 24;
 const SYSCALL_OPEN: usize = 56;
 const SYSCALL_CLOSE: usize = 57;
@@ -9,6 +11,8 @@ const SYSCALL_WRITE: usize = 64;
 const SYSCALL_EXIT: usize = 93;
 const SYSCALL_YIELD: usize = 124;
 const SYSCALL_KILL: usize = 129;
+const SYSCALL_SIGACTION: usize = 134;
+const SYSCALL_SIGPROCMASK: usize = 135;
 const SYSCALL_GET_TIME: usize = 169;
 const SYSCALL_GETPID: usize = 172;
 const SYSCALL_FORK: usize = 220;
@@ -91,3 +95,11 @@ pub fn sys_exec(path: &str, args: &[*const u8]) -> isize {
 pub fn sys_waitpid(pid: isize, exit_code: *mut i32) -> isize {
     syscall(SYSCALL_WAITPID, [pid as usize, exit_code as usize, 0])
 }
+
+pub fn sys_sigaction(signum: usize, action: *const SignalAction, old_action: *const SignalAction) -> isize {
+    syscall(SYSCALL_SIGACTION, [signum, action as usize, old_action as usize])
+}
+
+pub fn sys_sigprocmask(mask: u32) -> isize {
+    syscall(SYSCALL_SIGPROCMASK, [mask as usize, 0, 0])
+}