arch/um/os-Linux/irq.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2017 - Cambridge Greys Ltd
   4  * Copyright (C) 2011 - 2014 Cisco Systems Inc
   5  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   6  */
   7
   8 #include <stdlib.h>
   9 #include <errno.h>
  10 #include <sys/epoll.h>
  11 #include <signal.h>
  12 #include <string.h>
  13 #include <irq_user.h>
  14 #include <os.h>
  15 #include <um_malloc.h>
  16
  17 /* Epoll support */
  18
  19 static int epollfd = -1;
  20
  21 #define MAX_EPOLL_EVENTS 64
  22
  23 static struct epoll_event epoll_events[MAX_EPOLL_EVENTS];
  24
  25 /* Helper to return an Epoll data pointer from an epoll event structure.
  26  * We need to keep this one on the userspace side to keep includes separate
  27  */
  28
  29 void *os_epoll_get_data_pointer(int index)
  30 {
  31         return epoll_events[index].data.ptr;
  32 }
  33
  34 /* Helper to compare events versus the events in the epoll structure.
  35  * Same as above - needs to be on the userspace side
  36  */
  37
  38
  39 int os_epoll_triggered(int index, int events)
  40 {
  41         return epoll_events[index].events & events;
  42 }
  43 /* Helper to set the event mask.
  44  * The event mask is opaque to the kernel side, because it does not have
  45  * access to the right includes/defines for EPOLL constants.
  46  */
  47
  48 int os_event_mask(enum um_irq_type irq_type)
  49 {
  50         if (irq_type == IRQ_READ)
  51                 return EPOLLIN | EPOLLPRI | EPOLLERR | EPOLLHUP | EPOLLRDHUP;
  52         if (irq_type == IRQ_WRITE)
  53                 return EPOLLOUT;
  54         return 0;
  55 }
  56
  57 /*
  58  * Initial Epoll Setup
  59  */
  60 int os_setup_epoll(void)
  61 {
  62         epollfd = epoll_create(MAX_EPOLL_EVENTS);
  63         return epollfd;
  64 }
  65
  66 /*
  67  * Helper to run the actual epoll_wait
  68  */
  69 int os_waiting_for_events_epoll(void)
  70 {
  71         int n, err;
  72
  73         n = epoll_wait(epollfd,
  74                 (struct epoll_event *) &epoll_events, MAX_EPOLL_EVENTS, 0);
  75         if (n < 0) {
  76                 err = -errno;
  77                 if (errno != EINTR)
  78                         printk(
  79                                 UM_KERN_ERR "os_waiting_for_events:"
  80                                 " epoll returned %d, error = %s\n", n,
  81                                 strerror(errno)
  82                         );
  83                 return err;
  84         }
  85         return n;
  86 }
  87
  88
  89 /*
  90  * Helper to add a fd to epoll
  91  */
  92 int os_add_epoll_fd(int events, int fd, void *data)
  93 {
  94         struct epoll_event event;
  95         int result;
  96
  97         event.data.ptr = data;
  98         event.events = events | EPOLLET;
  99         result = epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &event);
 100         if ((result) && (errno == EEXIST))
 101                 result = os_mod_epoll_fd(events, fd, data);
 102         if (result)
 103                 printk("epollctl add err fd %d, %s\n", fd, strerror(errno));
 104         return result;
 105 }
 106
 107 /*
 108  * Helper to mod the fd event mask and/or data backreference
 109  */
 110 int os_mod_epoll_fd(int events, int fd, void *data)
 111 {
 112         struct epoll_event event;
 113         int result;
 114
 115         event.data.ptr = data;
 116         event.events = events;
 117         result = epoll_ctl(epollfd, EPOLL_CTL_MOD, fd, &event);
 118         if (result)
 119                 printk(UM_KERN_ERR
 120                         "epollctl mod err fd %d, %s\n", fd, strerror(errno));
 121         return result;
 122 }
 123
 124 /*
 125  * Helper to delete the epoll fd
 126  */
 127 int os_del_epoll_fd(int fd)
 128 {
 129         struct epoll_event event;
 130         int result;
 131         /* This is quiet as we use this as IO ON/OFF - so it is often
 132          * invoked on a non-existent fd
 133          */
 134         result = epoll_ctl(epollfd, EPOLL_CTL_DEL, fd, &event);
 135         return result;
 136 }
 137
 138 void os_set_ioignore(void)
 139 {
 140         signal(SIGIO, SIG_IGN);
 141 }
 142
 143 void os_close_epoll_fd(void)
 144 {
 145         /* Needed so we do not leak an fd when rebooting */
 146         os_close_file(epollfd);
 147 }