Decoupling Architectural-specific Code (#35)

[lunaix-os.git] / lunaix-os / kernel / process / signal.c

diff --git a/lunaix-os/kernel/process/signal.c b/lunaix-os/kernel/process/signal.c
index 9933682a047e49c8c303370c7bbd571ed07c4472..e40526ee9bb6fd2583a286e2645ffadfefcc71a3 100644 (file)
--- a/lunaix-os/kernel/process/signal.c
+++ b/lunaix-os/kernel/process/signal.c
@@ -4,202 +4,355 @@
 #include <lunaix/spike.h>
 #include <lunaix/status.h>
 #include <lunaix/syscall.h>
 #include <lunaix/spike.h>
 #include <lunaix/status.h>
 #include <lunaix/syscall.h>

+#include <lunaix/syslog.h>
+#include <lunaix/mm/valloc.h>

 
 #include <klibc/string.h>
 
 
 #include <klibc/string.h>
 

+#include <sys/mm/mempart.h>
+
+LOG_MODULE("SIG")
+

 extern struct scheduler sched_ctx; /* kernel/sched.c */
 
 extern struct scheduler sched_ctx; /* kernel/sched.c */
 

-void __USER__
-default_sighandler_term(int signum)
+#define UNMASKABLE (sigset(SIGKILL) | sigset(SIGTERM) | sigset(SIGILL))
+#define TERMSIG (sigset(SIGSEGV) | sigset(SIGINT) | UNMASKABLE)
+#define CORE (sigset(SIGSEGV))
+#define within_kstack(addr)                                                    \
+    (KSTACK_AREA <= (addr) && (addr) <= KSTACK_AREA_END)
+
+static inline void
+signal_terminate(int caused_by)

 {
 {

-    _exit(signum);
+    terminate_current(caused_by | PEXITSIG);

 }
 
 }
 

-void* default_handlers[_SIG_NUM] = {
-    // TODO: 添加默认handler
-    [_SIGINT] = default_sighandler_term,  [_SIGTERM] = default_sighandler_term,
-    [_SIGKILL] = default_sighandler_term, [_SIGSEGV] = default_sighandler_term,
-    [_SIGINT] = default_sighandler_term,
-};
-

 // Referenced in kernel/asm/x86/interrupt.S
 void*
 signal_dispatch()
 {
 // Referenced in kernel/asm/x86/interrupt.S
 void*
 signal_dispatch()
 {

-    if (!__current->sig_pending) {
+    if (kernel_process(__current)) {
+        // signal is undefined under 'kernel process'
+        return 0;
+    }
+
+    if (!pending_sigs(current_thread)) {

         // 没有待处理信号
         return 0;
     }
 
         // 没有待处理信号
         return 0;
     }
 

-    int sig_selected =
-      31 - __builtin_clz(__current->sig_pending &
-                         ~(__current->sig_mask | __current->sig_inprogress));
+    struct sigregistry* sigreg = __current->sigreg;
+    struct sigctx* psig = &current_thread->sigctx;
+    struct sigact* prev_working = active_signal(current_thread);
+    sigset_t mask = psig->sig_mask | (prev_working ? prev_working->sa_mask : 0);

 
 

-    __SIGCLEAR(__current->sig_pending, sig_selected);
+    int sig_selected = 31 - clz(psig->sig_pending & ~mask);
+    sigset_clear(psig->sig_pending, sig_selected);

 
 

-    if (sig_selected == 0) {
+    if (!sig_selected) {

         // SIG0 is reserved
         return 0;
     }
 
         // SIG0 is reserved
         return 0;
     }
 

-    if (!__current->sig_handler[sig_selected] &&
-        !default_handlers[sig_selected]) {
-        // 如果该信号没有handler，则忽略
+    struct sigact* action = sigreg->signals[sig_selected];
+    if (!action || !action->sa_actor) {
+        if (sigset_test(TERMSIG, sig_selected)) {
+            signal_terminate(sig_selected);
+            schedule();
+            // never return
+        }

         return 0;
     }
 
         return 0;
     }
 

-    uintptr_t ustack = __current->ustack_top & ~0xf;
-
-    if ((int)(ustack - USTACK_END) < (int)sizeof(struct proc_sig)) {
+    ptr_t ustack = current_thread->ustack_top;
+    ptr_t ustack_start = current_thread->ustack->start;
+    if ((int)(ustack - ustack_start) < (int)sizeof(struct proc_sig)) {

         // 用户栈没有空间存放信号上下文
         return 0;
     }
 
         // 用户栈没有空间存放信号上下文
         return 0;
     }
 

-    struct proc_sig* sig_ctx =
-      (struct proc_sig*)(ustack - sizeof(struct proc_sig));
+    struct proc_sig* sigframe =
+        (struct proc_sig*)((ustack - sizeof(struct proc_sig)) & ~0xf);

 
 

-    /*
-        这是一个相当恶心的坑。
-        问题是出在原本的sig_ctx->prev_context = __current->intr_ctx的上面
-        这个语句会被gcc在编译时，用更加高效的 rep movsl 来代替。
+    sigframe->sig_num = sig_selected;
+    sigframe->sigact = action->sa_actor;
+    sigframe->sighand = action->sa_handler;

 
 

-        由于我们采用按需分页，所以在很多情况下，用户栈实际被分配的空间不允许我们进行完整的
-        注入，而需要走page fault handler进行动态分页。
+    sigframe->saved_hstate = current_thread->hstate;

 
 

-        竞态条件就出现在这里！
+    sigactive_push(current_thread, sig_selected);

 
 

-        假若我们的__current->intr_ctx注入了一半，然后产生page-fault中断，
-        那么这就会导致我们的__current->intr_ctx被这个page-fault中断导致的
-        上下文信息覆盖。那么当page-fault handler成功分配了一个页，返回，
-        拷贝也就得以进行。遗憾的是，只不过这次拷贝的内容和前面的拷贝是没有任何的关系
-        （因为此时的intr_ctx已经不是之前的intr_ctx了！）
-        而这就会导致我们保存在信号上下文中的进程上下文信息不完整，从而在soft_iret时
-        触发#GP。
+    return sigframe;
+}

 
 

-        解决办法就是先吧intr_ctx拷贝到一个静态分配的区域里，然后再注入到用户栈。
-    */
-    static volatile struct proc_sigstate __temp_save;
-    __temp_save.proc_regs = __current->intr_ctx;
-    memcpy(__temp_save.fxstate, __current->fxstate, 512);
+static inline void must_inline
+__set_signal(struct thread* thread, signum_t signum) 
+{
+    raise_signal(thread, signum);

 
 

-    sig_ctx->prev_context = __temp_save;
+    // for these mutually exclusive signal
+    if (signum == SIGCONT || signum == SIGSTOP) {
+        sigset_clear(thread->sigctx.sig_pending, signum ^ 1);
+    }
+    
+    struct sigact* sig = sigact_of(thread->process, signum);
+    if (sig) {
+        sig->sender = __current->pid;
+    }
+}

 
 

-    sig_ctx->sig_num = sig_selected;
-    sig_ctx->signal_handler = __current->sig_handler[sig_selected];
+static inline void must_inline
+__set_signal_all_threads(struct proc_info* proc, signum_t signum) 
+{
+    struct thread *pos, *n;
+    llist_for_each(pos, n, &proc->threads, proc_sibs) {
+        __set_signal(pos, signum);
+    }
+}

 
 

-    if (!sig_ctx->signal_handler) {
-        // 如果没有用户自定义的Handler，则使用系统默认Handler。
-        sig_ctx->signal_handler = default_handlers[sig_selected];
+void
+thread_setsignal(struct thread* thread, signum_t signum)
+{
+    if (unlikely(kernel_process(thread->process))) {
+        return;

     }
 
     }
 

-    __SIGSET(__current->sig_inprogress, sig_selected);
+    __set_signal(thread, signum);
+}

 
 

-    return sig_ctx;
+void
+proc_setsignal(struct proc_info* proc, signum_t signum)
+{
+    if (unlikely(kernel_process(proc))) {
+        return;
+    }
+
+    // FIXME handle signal delivery at process level.
+    switch (signum)
+    {
+    case SIGKILL:
+        signal_terminate(signum);
+        break;
+    case SIGCONT:
+    case SIGSTOP:
+        __set_signal_all_threads(proc, signum);
+    default:
+        break;
+    }
+    
+    __set_signal(proc->th_active, signum);

 }
 
 int
 }
 
 int

-signal_send(pid_t pid, int signum)
+signal_send(pid_t pid, signum_t signum)

 {
 {

-    if (signum < 0 || signum >= _SIG_NUM) {
-        __current->k_status = EINVAL;
+    if (signum >= _SIG_NUM) {
+        syscall_result(EINVAL);

         return -1;
     }
 
         return -1;
     }
 

+    pid_t sender_pid = __current->pid;

     struct proc_info* proc;
     struct proc_info* proc;

+

     if (pid > 0) {
         proc = get_process(pid);
         goto send_single;
     } else if (!pid) {
         proc = __current;
         goto send_grp;
     if (pid > 0) {
         proc = get_process(pid);
         goto send_single;
     } else if (!pid) {
         proc = __current;
         goto send_grp;

-    } else if (pid < -1) {
+    } else if (pid < 0) {

         proc = get_process(-pid);
         goto send_grp;
     } else {
         // TODO: send to all process.
         //  But I don't want to support it yet.
         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 = EINVAL;
+        syscall_result(EINVAL);

         return -1;
     }
 
         return -1;
     }
 

-send_grp:
+send_grp: ;

     struct proc_info *pos, *n;
     llist_for_each(pos, n, &proc->grp_member, grp_member)
     {
     struct proc_info *pos, *n;
     llist_for_each(pos, n, &proc->grp_member, grp_member)
     {

-        __SIGSET(pos->sig_pending, signum);
+        proc_setsignal(pos, signum);

     }
 
 send_single:
     }
 
 send_single:

-    if (PROC_TERMINATED(proc->state)) {
-        __current->k_status = EINVAL;
+    if (proc_terminated(proc)) {
+        syscall_result(EINVAL);

         return -1;
     }
         return -1;
     }

-    __SIGSET(proc->sig_pending, signum);
+
+    proc_setsignal(proc, signum);
+

     return 0;
 }
 
     return 0;
 }
 

-__DEFINE_LXSYSCALL1(int, sigreturn, struct proc_sig, *sig_ctx)
+void
+signal_dup_context(struct sigctx* dest_ctx) 

 {
 {

-    memcpy(__current->fxstate, sig_ctx->prev_context.fxstate, 512);
-    __current->intr_ctx = sig_ctx->prev_context.proc_regs;
-    __current->flags &= ~PROC_FINPAUSE;
-    __SIGCLEAR(__current->sig_inprogress, sig_ctx->sig_num);
-    schedule();
+    struct sigctx* old_ctx = &current_thread->sigctx;
+    memcpy(dest_ctx, old_ctx, sizeof(struct sigctx));
+}
+
+void
+signal_dup_registry(struct sigregistry* dest_reg)
+{
+    struct sigregistry* oldreg = __current->sigreg;
+    for (int i = 0; i < _SIG_NUM; i++) {
+        struct sigact* oldact = oldreg->signals[i];
+        if (!oldact) {
+            continue;
+        }
+        
+        struct sigact* newact = valloc(sizeof(struct sigact));
+        memcpy(newact, oldact, sizeof(struct sigact));
+
+        dest_reg->signals[i] = newact;
+    }
+}
+
+void
+signal_reset_context(struct sigctx* sigctx) {
+    memset(sigctx, 0, sizeof(struct sigctx));
+}
+
+void
+signal_reset_registry(struct sigregistry* sigreg) {
+    for (int i = 0; i < _SIG_NUM; i++) {
+        struct sigact* act = sigreg->signals[i];
+        if (act) {
+            vfree(act);
+            sigreg->signals[i] = NULL;
+        }
+    }
+}
+
+void
+signal_free_registry(struct sigregistry* sigreg) {
+    signal_reset_registry(sigreg);
+    vfree(sigreg);

 }
 
 }
 

-__DEFINE_LXSYSCALL3(int,
-                    sigprocmask,
-                    int,
-                    how,
-                    const sigset_t,
-                    *set,
-                    sigset_t,
-                    *oldset)
+static bool
+signal_set_sigmask(struct thread* thread, int how, sigset_t* oldset, sigset_t* set)

 {
 {

-    *oldset = __current->sig_mask;
+    struct sigctx* sh = &current_thread->sigctx;
+    *oldset = sh->sig_mask;
+

     if (how == _SIG_BLOCK) {
     if (how == _SIG_BLOCK) {

-        __current->sig_mask |= *set;
+        sigset_union(sh->sig_mask, *set);

     } else if (how == _SIG_UNBLOCK) {
     } else if (how == _SIG_UNBLOCK) {

-        __current->sig_mask &= ~(*set);
+        sigset_intersect(sh->sig_mask, ~(*set));

     } else if (how == _SIG_SETMASK) {
     } else if (how == _SIG_SETMASK) {

-        __current->sig_mask = *set;
+        sh->sig_mask = *set;

     } else {
     } else {

-        return 0;
+        return false;

     }
     }

-    __current->sig_mask &= ~_SIGNAL_UNMASKABLE;
-    return 1;
+
+    sigset_intersect(sh->sig_mask, ~UNMASKABLE);
+    return true;

 }
 
 }
 

-__DEFINE_LXSYSCALL2(int, signal, int, signum, sighandler_t, handler)
+__DEFINE_LXSYSCALL1(int, sigreturn, struct proc_sig, *sig_ctx)

 {
 {

-    if (signum <= 0 || signum >= _SIG_NUM) {
-        return -1;
+    struct sigctx* sigctx = &current_thread->sigctx;
+    struct sigact* active = active_signal(current_thread);
+
+    /* We choose signal#0 as our base case, that is sig#0 means no signal.
+        Therefore, it is an ill situation to return from such sigctx.
+    */
+    if (!active) {
+        signal_terminate(SIGSEGV);
+        schedule();

     }
 
     }
 

-    if ((__SIGNAL(signum) & _SIGNAL_UNMASKABLE)) {
-        return -1;
+    current_thread->hstate = sig_ctx->saved_hstate;
+    if (proc_terminated(__current)) {
+        __current->exit_code |= PEXITSIG;
+    } else if (sigset_test(CORE, sig_ctx->sig_num)) {
+        signal_terminate(sig_ctx->sig_num);
+    }
+
+    ptr_t ictx = (ptr_t)current_thread->hstate;
+
+    /*
+        Ensure our restored context is within kernel stack
+
+        This prevent user to forge their own context such that arbitrary code
+       can be executed as supervisor level
+    */
+    if (!within_kstack(ictx)) {
+        signal_terminate(SIGSEGV);

     }
 
     }
 

-    __current->sig_handler[signum] = (void*)handler;
+    sigactive_pop(current_thread);
+
+    schedule();

 
 

+    // never reach!

     return 0;
 }
 
     return 0;
 }
 

-void
-__do_pause()
+__DEFINE_LXSYSCALL3(
+    int, sigprocmask, int, how, const sigset_t, *set, sigset_t, *oldset)

 {
 {

-    __current->flags |= PROC_FINPAUSE;
+    // TODO maybe it is a good opportunity to introduce a process-wide 
+    //      signal mask?
+    
+    if (signal_set_sigmask(current_thread, how, oldset, set)) {
+        return 0;
+    }
+
+    syscall_result(EINVAL);
+    return -1;
+}

 
 

-    while ((__current->flags & PROC_FINPAUSE)) {
-        sched_yieldk();
+__DEFINE_LXSYSCALL3(
+    int, th_sigmask, int, how, const sigset_t, *set, sigset_t, *oldset)
+{
+    if (signal_set_sigmask(current_thread, how, oldset, set)) {
+        return 0;

     }
 
     }
 

-    __current->k_status = EINTR;
+    return EINVAL;
+}
+
+__DEFINE_LXSYSCALL2(int, sys_sigaction, int, signum, struct sigaction*, action)
+{
+    if (signum <= 0 || signum >= _SIG_NUM) {
+        return -1;
+    }
+
+    if (sigset_test(UNMASKABLE, signum)) {
+        return -1;
+    }
+
+    struct sigctx* sigctx = &current_thread->sigctx;
+    if (signum == sigctx->sig_active) {
+        return -1;
+    }
+
+    struct sigact* sa = sigact_of(__current, signum);
+
+    if (!sa) {
+        sa = vzalloc(sizeof(struct sigact));
+        set_sigact(__current, signum, sa);
+    }
+
+    sa->sa_actor = (void*)action->sa_sigaction;
+    sa->sa_handler = (void*)action->sa_handler;
+    sigset_union(sa->sa_mask, sigset(signum));
+
+    return 0;

 }
 
 __DEFINE_LXSYSCALL(int, pause)
 {
 }
 
 __DEFINE_LXSYSCALL(int, pause)
 {

-    __do_pause();
+    pause_current_thread();
+    sched_pass();
+
+    syscall_result(EINTR);

     return -1;
 }
 
     return -1;
 }
 


@@ -210,15 +363,19 @@ __DEFINE_LXSYSCALL2(int, kill, pid_t, pid, int, signum)
 
 __DEFINE_LXSYSCALL1(int, sigpending, sigset_t, *sigset)
 {
 
 __DEFINE_LXSYSCALL1(int, sigpending, sigset_t, *sigset)
 {

-    *sigset = __current->sig_pending;
+    *sigset = pending_sigs(current_thread);

     return 0;
 }
 
 __DEFINE_LXSYSCALL1(int, sigsuspend, sigset_t, *mask)
 {
     return 0;
 }
 
 __DEFINE_LXSYSCALL1(int, sigsuspend, sigset_t, *mask)
 {

-    sigset_t tmp = __current->sig_mask;
-    __current->sig_mask = (*mask) & ~_SIGNAL_UNMASKABLE;
-    __do_pause();
-    __current->sig_mask = tmp;
+    struct sigctx* sigctx = &current_thread->sigctx;
+    sigset_t tmp = current_thread->sigctx.sig_mask;
+    sigctx->sig_mask = (*mask) & ~UNMASKABLE;
+
+    pause_current_thread();
+    sched_pass();
+
+    sigctx->sig_mask = tmp;

     return -1;
 }
\ No newline at end of file
     return -1;
 }
\ No newline at end of file