+#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,
+ [_SIGKILL] = default_sighandler_term, [_SIGSEGV] = default_sighandler_term,
+ [_SIGINT] = default_sighandler_term,
};
+volatile isr_param __temp_save;
// 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]) {
struct proc_sig* sig_ctx =
(struct proc_sig*)(ustack - sizeof(struct proc_sig));
- sig_ctx->prev_context = __current->intr_ctx;
+ /*
+ 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。
+
+ 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。
+
+ 竞态条件就出现在这里！
+
+ 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。
+
+ 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。
+ */
+ __temp_save = __current->intr_ctx;
+ sig_ctx->prev_context = __temp_save;
+
sig_ctx->sig_num = sig_selected;
sig_ctx->signal_handler = __current->sig_handler[sig_selected];
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 = EINVAL;
+ 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 = EINVAL;
+ 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_TERMINATED(proc->state)) {
+ __current->k_status = EINVAL;
+ 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();
}
__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;
}
__current->sig_handler[signum] = (void*)handler;
return 0;
+}
+
+void
+__do_pause()
+{
+ __current->flags |= PROC_FINPAUSE;
+
+ while ((__current->flags & PROC_FINPAUSE)) {
+ sched_yieldk();
+ }
+
+ __current->k_status = EINTR;
+}
+
+__DEFINE_LXSYSCALL(int, pause)
+{
+ __do_pause();
+ return -1;
+}
+
+__DEFINE_LXSYSCALL2(int, kill, pid_t, pid, int, signum)
+{
+ return signal_send(pid, signum);
+}
+
+__DEFINE_LXSYSCALL1(int, sigpending, sigset_t, *sigset)
+{
+ *sigset = __current->sig_pending;
+ 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;
+ return -1;
}
\ No newline at end of file
git://scm.lunaixsky.com / lunaix-os.git / blobdiff