+++ /dev/null
-#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 (!__current->sig_pending) {
- // 没有待处理信号
- return 0;
- }
-
- int sig_selected =
- 31 - __builtin_clz(__current->sig_pending &
- ~(__current->sig_mask | __current->sig_inprogress));
-
- __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]) {
- // 如果该信号没有handler，则忽略
- return 0;
- }
-
- uintptr_t ustack = __current->ustack_top & ~0xf;
-
- if ((int)(ustack - USTACK_END) < (int)sizeof(struct proc_sig)) {
- // 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));
-
- /*
- 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];
-
- 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];
- }
-
- __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->flags &= ~PROC_FINPAUSE;
- __SIGCLEAR(__current->sig_inprogress, sig_ctx->sig_num);
- schedule();
-}
-
-__DEFINE_LXSYSCALL3(int,
- sigprocmask,
- int,
- how,
- const sigset_t,
- *set,
- sigset_t,
- *oldset)
-{
- *oldset = __current->sig_mask;
- if (how == _SIG_BLOCK) {
- __current->sig_mask |= *set;
- } else if (how == _SIG_UNBLOCK) {
- __current->sig_mask &= ~(*set);
- } else if (how == _SIG_SETMASK) {
- __current->sig_mask = *set;
- } else {
- return 0;
- }
- __current->sig_mask &= ~_SIGNAL_UNMASKABLE;
- return 1;
-}
-
-__DEFINE_LXSYSCALL2(int, signal, int, signum, sighandler_t, handler)
-{
- if (signum <= 0 || signum >= _SIG_NUM) {
- return -1;
- }
-
- 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