From: Minep <zelong56@gmail.com>
Date: Mon, 20 Jun 2022 23:19:49 +0000 (+0100)
Subject: feat: kill(2) implementation
X-Git-Url: https://scm.lunaixsky.com/lunaix-os.git/commitdiff_plain/cb529e7c1abcfe6b61241e47a780172031b82840?hp=2803826a2373620dbfce8a5bff1e6a01dd594953

feat: kill(2) implementation
feat: support more signal (SIGKILL, SIGSTOP, SIGCONT)
fix: [interrupt.S] change to callee-save register for safety
chore: formatting, renaming things
---

diff --git a/README.md b/README.md
index d2a6c09..8f5b488 100644
--- a/README.md
+++ b/README.md
@@ -20,7 +20,7 @@ LunaixOS - 一个简单的，详细的，POSIX兼容的（但愿！），带有
 + 多进程
 + 14个常见的Linux/POSIX系统调用（[附录1](#appendix1)）
 + 用户模式
-+ 信号机制（进行中）
++ 信号机制（测试中）
 
 ## 目录结构
 
@@ -67,7 +67,7 @@ LunaixOS - 一个简单的，详细的，POSIX兼容的（但愿！），带有
 ## 附录1：支持的系统调用<a id="appendix1"></a>
 
 ### Unix/Linux/POSIX
-1. `sleep(2)`
+1. `sleep(3)`
 1. `wait(2)`
 1. `waitpid(2)`
 1. `fork(2)`
@@ -80,7 +80,8 @@ LunaixOS - 一个简单的，详细的，POSIX兼容的（但愿！），带有
 1. `_exit(2)`
 1. `sigreturn(2)`
 1. `sigprocmask(2)`
-1. `signal(2)   `
+1. `signal(2)`
+1. `kill(2)`
 
 ### LunaixOS自有
 
diff --git a/lunaix-os/includes/lunaix/lunistd.h b/lunaix-os/includes/lunaix/lunistd.h
index 7a1c368..67f3174 100644
--- a/lunaix-os/includes/lunaix/lunistd.h
+++ b/lunaix-os/includes/lunaix/lunistd.h
@@ -20,4 +20,6 @@ __LXSYSCALL1(unsigned int, sleep, unsigned int, seconds)
 
 __LXSYSCALL(int, pause)
 
+__LXSYSCALL2(int, kill, pid_t, pid, int, signum)
+
 #endif /* __LUNAIX_UNISTD_H */
diff --git a/lunaix-os/includes/lunaix/lxsignal.h b/lunaix-os/includes/lunaix/lxsignal.h
new file mode 100644
index 0000000..5b54ffc
--- /dev/null
+++ b/lunaix-os/includes/lunaix/lxsignal.h
@@ -0,0 +1,9 @@
+#ifndef __LUNAIX_LXSIGNAL_H
+#define __LUNAIX_LXSIGNAL_H
+
+#include <lunaix/types.h>
+
+int
+signal_send(pid_t pid, int signum);
+
+#endif /* __LUNAIX_LXSIGNAL_H */
diff --git a/lunaix-os/includes/lunaix/process.h b/lunaix-os/includes/lunaix/process.h
index 2cd4330..589bfaa 100644
--- a/lunaix-os/includes/lunaix/process.h
+++ b/lunaix-os/includes/lunaix/process.h
@@ -22,6 +22,7 @@
 #define PROC_TERMMASK 0x6
 
 #define PROC_FINPAUSE 1
+#define PROC_FALRMSET (1 << 1)
 
 struct proc_mm
 {
@@ -66,6 +67,7 @@ struct proc_info
     int32_t k_status;
     sigset_t sig_pending;
     sigset_t sig_mask;
+    sigset_t sig_inprogress;
     int flags;
     void* sig_handler[_SIG_NUM];
     pid_t pgid;
diff --git a/lunaix-os/includes/lunaix/signal.h b/lunaix-os/includes/lunaix/signal.h
index d1f7041..5405aab 100644
--- a/lunaix-os/includes/lunaix/signal.h
+++ b/lunaix-os/includes/lunaix/signal.h
@@ -3,21 +3,24 @@
 
 #include <lunaix/syscall.h>
 
-#define _SIG_NUM 8
+#define _SIG_NUM 16
 
 #define _SIG_PENDING(bitmap, sig) ((bitmap) & (1 << (sig)))
 
-#define _SIGSEGV 0
-#define _SIGALRM 1
-#define _SIGCHLD 2
+#define _SIGSEGV 1
+#define _SIGALRM 2
+#define _SIGCHLD 3
 #define _SIGCLD _SIGCHLD
-#define _SIGINT 3
-#define _SIGKILL 4
-#define _SIGSTOP 5
-#define _SIGCONT 6
+#define _SIGINT 4
+#define _SIGKILL 5
+#define _SIGSTOP 6
+#define _SIGCONT 7
+#define _SIGTERM 8
 
 #define __SIGNAL(num) (1 << (num))
-#define __SET_SIGNAL(bitmap, num) (bitmap = bitmap | __SIGNAL(num))
+#define __SIGSET(bitmap, num) (bitmap = bitmap | __SIGNAL(num))
+#define __SIGTEST(bitmap, num) (bitmap & __SIGNAL(num))
+#define __SIGCLEAR(bitmap, num) ((bitmap) = (bitmap) & ~__SIGNAL(num))
 
 #define _SIGNAL_UNMASKABLE (__SIGNAL(_SIGKILL) | __SIGNAL(_SIGSTOP))
 
@@ -30,4 +33,13 @@ typedef void (*sighandler_t)(int);
 
 __LXSYSCALL2(int, signal, int, signum, sighandler_t, handler);
 
+__LXSYSCALL3(int,
+             sigprocmask,
+             int,
+             how,
+             const sigset_t,
+             *set,
+             sigset_t,
+             *oldset);
+
 #endif /* __LUNAIX_SIGNAL_H */
diff --git a/lunaix-os/includes/lunaix/syscall.h b/lunaix-os/includes/lunaix/syscall.h
index f695cf7..e1d3403 100644
--- a/lunaix-os/includes/lunaix/syscall.h
+++ b/lunaix-os/includes/lunaix/syscall.h
@@ -17,6 +17,7 @@
 #define __SYSCALL_sigprocmask 12
 #define __SYSCALL_signal 13
 #define __SYSCALL_pause 14
+#define __SYSCALL_kill 15
 
 #define __SYSCALL_MAX 0x100
 
diff --git a/lunaix-os/includes/lunaix/types.h b/lunaix-os/includes/lunaix/types.h
index 028792a..e91025a 100644
--- a/lunaix-os/includes/lunaix/types.h
+++ b/lunaix-os/includes/lunaix/types.h
@@ -3,15 +3,21 @@
 
 #include <stdint.h>
 
-#define PROCTERM 0x10000
-#define PROCSTOP 0x20000
+#define PEXITTERM 0x100
+#define PEXITSTOP 0x200
+#define PEXITSIG 0x400
+
+#define PEXITNUM(flag, code) (flag | (code & 0xff))
 
 #define WNOHANG 1
 #define WUNTRACED 2
-#define WEXITSTATUS(wstatus) ((wstatus & 0xffff))
-#define WIFSTOPPED(wstatus) ((wstatus & PROCSTOP))
+#define WEXITSTATUS(wstatus) ((wstatus & 0xff))
+#define WIFSTOPPED(wstatus) ((wstatus & PEXITSTOP))
 #define WIFEXITED(wstatus)                                                     \
-    ((wstatus & PROCTERM) && ((short)WEXITSTATUS(wstatus) >= 0))
+    ((wstatus & PEXITTERM) && ((char)WEXITSTATUS(wstatus) >= 0))
+
+#define WIFSIGNALED(wstatus) ((wstatus & PEXITSIG))
+// TODO: WTERMSIG
 
 typedef int32_t pid_t;
 
diff --git a/lunaix-os/kernel/asm/x86/interrupt.S b/lunaix-os/kernel/asm/x86/interrupt.S
index 48dff2f..7c40673 100644
--- a/lunaix-os/kernel/asm/x86/interrupt.S
+++ b/lunaix-os/kernel/asm/x86/interrupt.S
@@ -157,17 +157,17 @@
         # 约定
         # arg1: 目标进程PCB地址 (next
 
-        popl %ecx               # next
+        popl %ebx               # next
         movl __current, %eax    
-        movl 88(%eax), %ebx     # __current->pagetable
-        movl 88(%ecx), %eax     # next->pagetable
+        movl 88(%eax), %ecx     # __current->pagetable
+        movl 88(%ebx), %eax     # next->pagetable
         
-        cmpl %ebx, %eax         # if(next->pagtable != __current->pagetable) {
+        cmpl %ecx, %eax         # if(next->pagtable != __current->pagetable) {
         jz 1f
         movl %eax, %cr3         #   cpu_lcr3(next->pagetable)
                                 # }
     1:
-        movl %ecx, __current    # __current = next
+        movl %ebx, __current    # __current = next
 
         # 我们已经处在了新的地址空间，为了避免影响其先前的栈布局
         # 需要使用一个临时的栈空间
@@ -178,7 +178,7 @@
         jz 1f
         jmp handle_signal
     1:
-        leal 8(%ecx), %eax
+        leal 8(%ebx), %eax
         jmp soft_iret
 
     .global handle_signal
diff --git a/lunaix-os/kernel/asm/x86/pfault.c b/lunaix-os/kernel/asm/x86/pfault.c
index 30fd498..9e12444 100644
--- a/lunaix-os/kernel/asm/x86/pfault.c
+++ b/lunaix-os/kernel/asm/x86/pfault.c
@@ -1,5 +1,6 @@
 #include <arch/x86/interrupts.h>
 #include <lunaix/common.h>
+#include <lunaix/lxsignal.h>
 #include <lunaix/mm/mm.h>
 #include <lunaix/mm/pmm.h>
 #include <lunaix/mm/region.h>
@@ -92,7 +93,8 @@ segv_term:
             ptr,
             param->cs,
             param->eip);
-    terminate_proc(LXSEGFAULT);
+    signal_send(__current->pid, _SIGSEGV);
+    schedule();
     // should not reach
     while (1)
         ;
diff --git a/lunaix-os/kernel/asm/x86/syscall.S b/lunaix-os/kernel/asm/x86/syscall.S
index 0922a96..b323640 100644
--- a/lunaix-os/kernel/asm/x86/syscall.S
+++ b/lunaix-os/kernel/asm/x86/syscall.S
@@ -22,6 +22,7 @@
         .long __lxsys_sigprocmask
         .long __lxsys_signal
         .long __lxsys_pause
+        .long __lxsys_kill          /* 15 */
         2:
         .rept __SYSCALL_MAX - (2b - 1b)/4
             .long 0
diff --git a/lunaix-os/kernel/k_init.c b/lunaix-os/kernel/k_init.c
index 257112e..447bff7 100644
--- a/lunaix-os/kernel/k_init.c
+++ b/lunaix-os/kernel/k_init.c
@@ -121,6 +121,7 @@ spawn_proc0()
                                    .eip = (void*)__proc0,
                                    .ss = KDATA_SEG,
                                    .eflags = cpu_reflags() };
+    proc0->parent = proc0;
 
     // 方案1：必须在读取eflags之后禁用。否则当进程被调度时，中断依然是关闭的！
     // cpu_disable_interrupt();
diff --git a/lunaix-os/kernel/lxinit.c b/lunaix-os/kernel/lxinit.c
index 2de87c5..fa5ce38 100644
--- a/lunaix-os/kernel/lxinit.c
+++ b/lunaix-os/kernel/lxinit.c
@@ -25,6 +25,14 @@ sigchild_handler(int signum)
     kprintf(KINFO "SIGCHLD received\n");
 }
 
+void __USER__
+sigsegv_handler(int signum)
+{
+    pid_t pid = getpid();
+    kprintf(KWARN "SIGSEGV received on process %d\n", pid);
+    _exit(signum);
+}
+
 void __USER__
 _lxinit_main()
 {
@@ -39,6 +47,7 @@ _lxinit_main()
 #endif
 
     signal(_SIGCHLD, sigchild_handler);
+    signal(_SIGSEGV, sigsegv_handler);
 
     int status;
 #ifdef WAIT_DEMO
@@ -67,9 +76,10 @@ _lxinit_main()
 
     waitpid(-1, &status, WNOHANG);
 
-    for (size_t i = 0; i < 10; i++) {
+    for (size_t i = 0; i < 5; i++) {
         pid_t pid = 0;
         if (!(pid = fork())) {
+            signal(_SIGSEGV, sigsegv_handler);
             sleep(i);
             if (i == 3) {
                 i = *(int*)0xdeadc0de; // seg fault!
@@ -83,7 +93,11 @@ _lxinit_main()
 
     while ((p = wait(&status)) >= 0) {
         short code = WEXITSTATUS(status);
-        if (WIFEXITED(status)) {
+        if (WIFSIGNALED(status)) {
+            kprintf(KINFO "Process %d terminated by signal, exit_code: %d\n",
+                    p,
+                    code);
+        } else if (WIFEXITED(status)) {
             kprintf(KINFO "Process %d exited with code %d\n", p, code);
         } else {
             kprintf(KWARN "Process %d aborted with code %d\n", p, code);
diff --git a/lunaix-os/kernel/sched.c b/lunaix-os/kernel/sched.c
index 50f5f67..f2ce4a2 100644
--- a/lunaix-os/kernel/sched.c
+++ b/lunaix-os/kernel/sched.c
@@ -44,9 +44,6 @@ sched_init()
 void
 run(struct proc_info* proc)
 {
-    if (!(__current->state & ~PROC_RUNNING)) {
-        __current->state = PROC_STOPPED;
-    }
     proc->state = PROC_RUNNING;
 
     /*
@@ -65,6 +62,23 @@ run(struct proc_info* proc)
                  "jmp switch_to\n" ::"r"(proc)); // kernel/asm/x86/interrupt.S
 }
 
+int
+can_schedule(struct proc_info* proc)
+{
+    if (__SIGTEST(proc->sig_pending, _SIGKILL)) {
+        // 如果进程受到SIGKILL，则直接终止，该进程不给予调度。
+        terminate_proc(PEXITNUM(PEXITSIG, _SIGKILL));
+        return 0;
+    } else if (__SIGTEST(proc->sig_pending, _SIGCONT)) {
+        __SIGCLEAR(proc->sig_pending, _SIGSTOP);
+    } else if (__SIGTEST(proc->sig_pending, _SIGSTOP)) {
+        // 如果进程受到SIGSTOP，则该进程不给予调度。
+        return 0;
+    }
+
+    return 1;
+}
+
 void
 schedule()
 {
@@ -77,7 +91,13 @@ schedule()
     struct proc_info* next;
     int prev_ptr = sched_ctx.procs_index;
     int ptr = prev_ptr;
+
+    if (!(__current->state & ~PROC_RUNNING)) {
+        __current->state = PROC_STOPPED;
+    }
+
     // round-robin scheduler
+redo:
     do {
         ptr = (ptr + 1) % sched_ctx.ptable_len;
         next = &sched_ctx._procs[ptr];
@@ -85,6 +105,11 @@ schedule()
 
     sched_ctx.procs_index = ptr;
 
+    if (!can_schedule(next)) {
+        // 如果该进程不给予调度，则尝试重新选择
+        goto redo;
+    }
+
     run(next);
 }
 
@@ -117,6 +142,7 @@ __DEFINE_LXSYSCALL1(unsigned int, sleep, unsigned int, seconds)
 __DEFINE_LXSYSCALL1(void, exit, int, status)
 {
     terminate_proc(status);
+    schedule();
 }
 
 __DEFINE_LXSYSCALL(void, yield)
@@ -154,11 +180,11 @@ repeat:
     {
         if (!~wpid || proc->pid == wpid || proc->pgid == -wpid) {
             if (proc->state == PROC_TERMNAT && !options) {
-                status_flags |= PROCTERM;
+                status_flags |= PEXITTERM;
                 goto done;
             }
             if (proc->state == PROC_STOPPED && (options & WUNTRACED)) {
-                status_flags |= PROCSTOP;
+                status_flags |= PEXITSTOP;
                 goto done;
             }
         }
@@ -172,7 +198,8 @@ repeat:
 
 done:
     cpu_disable_interrupt();
-    *status = (proc->exit_code & 0xffff) | status_flags;
+    status_flags |= PEXITSIG * (proc->sig_inprogress != 0);
+    *status = proc->exit_code | status_flags;
     return destroy_process(proc->pid);
 }
 
@@ -219,12 +246,12 @@ commit_process(struct proc_info* process)
     }
 
     // every process is the child of first process (pid=1)
-    if (process->parent) {
-        llist_append(&process->parent->children, &process->siblings);
-    } else {
-        process->parent = &sched_ctx._procs[0];
+    if (!process->parent) {
+        process->parent = &sched_ctx._procs[1];
     }
 
+    llist_append(&process->parent->children, &process->siblings);
+
     process->state = PROC_STOPPED;
 }
 
@@ -265,9 +292,7 @@ terminate_proc(int exit_code)
     __current->state = PROC_TERMNAT;
     __current->exit_code = exit_code;
 
-    __SET_SIGNAL(__current->parent->sig_pending, _SIGCHLD);
-
-    schedule();
+    __SIGSET(__current->parent->sig_pending, _SIGCHLD);
 }
 
 struct proc_info*
diff --git a/lunaix-os/kernel/signal.c b/lunaix-os/kernel/signal.c
index 80a7098..c3a6c07 100644
--- a/lunaix-os/kernel/signal.c
+++ b/lunaix-os/kernel/signal.c
@@ -1,33 +1,45 @@
+#include <lunaix/lunistd.h>
+#include <lunaix/lxsignal.h>
 #include <lunaix/process.h>
 #include <lunaix/sched.h>
 #include <lunaix/signal.h>
+#include <lunaix/spike.h>
 #include <lunaix/status.h>
 #include <lunaix/syscall.h>
 
 extern struct scheduler sched_ctx; /* kernel/sched.c */
 
+void __USER__
+default_sighandler_term(int signum)
+{
+    _exit(signum);
+}
+
 void* default_handlers[_SIG_NUM] = {
     // TODO: 添加默认handler
+    [_SIGINT] = default_sighandler_term,
+    [_SIGTERM] = default_sighandler_term,
 };
 
 // Referenced in kernel/asm/x86/interrupt.S
 void*
 signal_dispatch()
 {
-    // if (!(SEL_RPL(__current->intr_ctx.cs))) {
-    //     // 同特权级间调度不进行信号处理
-    //     return 0;
-    // }
-
     if (!__current->sig_pending) {
         // 没有待处理信号
         return 0;
     }
 
     int sig_selected =
-      31 - __builtin_clz(__current->sig_pending & ~__current->sig_mask);
+      31 - __builtin_clz(__current->sig_pending &
+                         ~(__current->sig_mask | __current->sig_inprogress));
 
-    __current->sig_pending = __current->sig_pending & ~__SIGNAL(sig_selected);
+    __SIGCLEAR(__current->sig_pending, sig_selected);
+
+    if (sig_selected == 0) {
+        // SIG0 is reserved
+        return 0;
+    }
 
     if (!__current->sig_handler[sig_selected] &&
         !default_handlers[sig_selected]) {
@@ -54,16 +66,58 @@ signal_dispatch()
         sig_ctx->signal_handler = default_handlers[sig_selected];
     }
 
-    __current->sig_mask |= __SIGNAL(sig_selected);
+    __SIGSET(__current->sig_inprogress, sig_selected);
 
     return sig_ctx;
 }
 
+int
+signal_send(pid_t pid, int signum)
+{
+    if (signum < 0 || signum >= _SIG_NUM) {
+        __current->k_status = LXINVL;
+        return -1;
+    }
+
+    struct proc_info* proc;
+    if (pid > 0) {
+        proc = get_process(pid);
+        goto send_single;
+    } else if (!pid) {
+        proc = __current;
+        goto send_grp;
+    } else if (pid < -1) {
+        proc = get_process(-pid);
+        goto send_grp;
+    } else {
+        // TODO: send to all process.
+        //  But I don't want to support it yet.
+        __current->k_status = LXINVL;
+        return -1;
+    }
+
+send_grp:
+    struct proc_info *pos, *n;
+    llist_for_each(pos, n, &proc->grp_member, grp_member)
+    {
+        __SIGSET(pos->sig_pending, signum);
+    }
+    return 0;
+
+send_single:
+    if ((proc->state & PROC_TERMMASK)) {
+        __current->k_status = LXINVL;
+        return -1;
+    }
+    __SIGSET(proc->sig_pending, signum);
+    return 0;
+}
+
 __DEFINE_LXSYSCALL1(int, sigreturn, struct proc_sig, *sig_ctx)
 {
     __current->intr_ctx = sig_ctx->prev_context;
-    __current->sig_mask &= ~__SIGNAL(sig_ctx->sig_num);
     __current->flags &= ~PROC_FINPAUSE;
+    __SIGCLEAR(__current->sig_inprogress, sig_ctx->sig_num);
     schedule();
 }
 
@@ -92,11 +146,11 @@ __DEFINE_LXSYSCALL3(int,
 
 __DEFINE_LXSYSCALL2(int, signal, int, signum, sighandler_t, handler)
 {
-    if (signum < 0 || signum >= _SIG_NUM) {
+    if (signum <= 0 || signum >= _SIG_NUM) {
         return -1;
     }
 
-    if (((1 << signum) & _SIGNAL_UNMASKABLE)) {
+    if ((__SIGNAL(signum) & _SIGNAL_UNMASKABLE)) {
         return -1;
     }
 
@@ -116,4 +170,9 @@ __DEFINE_LXSYSCALL(int, pause)
     })
     __current->k_status = EINTR;
     return -1;
+}
+
+__DEFINE_LXSYSCALL2(int, kill, pid_t, pid, int, signum)
+{
+    return signal_send(pid, signum);
 }
\ No newline at end of file