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-rw-r--r--arch/um/os-Linux/sigio.c546
1 files changed, 546 insertions, 0 deletions
diff --git a/arch/um/os-Linux/sigio.c b/arch/um/os-Linux/sigio.c
new file mode 100644
index 000000000..75558080d
--- /dev/null
+++ b/arch/um/os-Linux/sigio.c
@@ -0,0 +1,546 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2002 - 2008 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ */
+
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <pty.h>
+#include <sched.h>
+#include <signal.h>
+#include <string.h>
+#include <kern_util.h>
+#include <init.h>
+#include <os.h>
+#include <sigio.h>
+#include <um_malloc.h>
+
+/*
+ * Protected by sigio_lock(), also used by sigio_cleanup, which is an
+ * exitcall.
+ */
+static int write_sigio_pid = -1;
+static unsigned long write_sigio_stack;
+
+/*
+ * These arrays are initialized before the sigio thread is started, and
+ * the descriptors closed after it is killed. So, it can't see them change.
+ * On the UML side, they are changed under the sigio_lock.
+ */
+#define SIGIO_FDS_INIT {-1, -1}
+
+static int write_sigio_fds[2] = SIGIO_FDS_INIT;
+static int sigio_private[2] = SIGIO_FDS_INIT;
+
+struct pollfds {
+ struct pollfd *poll;
+ int size;
+ int used;
+};
+
+/*
+ * Protected by sigio_lock(). Used by the sigio thread, but the UML thread
+ * synchronizes with it.
+ */
+static struct pollfds current_poll;
+static struct pollfds next_poll;
+static struct pollfds all_sigio_fds;
+
+static int write_sigio_thread(void *unused)
+{
+ struct pollfds *fds, tmp;
+ struct pollfd *p;
+ int i, n, respond_fd;
+ char c;
+
+ os_fix_helper_signals();
+ fds = &current_poll;
+ while (1) {
+ n = poll(fds->poll, fds->used, -1);
+ if (n < 0) {
+ if (errno == EINTR)
+ continue;
+ printk(UM_KERN_ERR "write_sigio_thread : poll returned "
+ "%d, errno = %d\n", n, errno);
+ }
+ for (i = 0; i < fds->used; i++) {
+ p = &fds->poll[i];
+ if (p->revents == 0)
+ continue;
+ if (p->fd == sigio_private[1]) {
+ CATCH_EINTR(n = read(sigio_private[1], &c,
+ sizeof(c)));
+ if (n != sizeof(c))
+ printk(UM_KERN_ERR
+ "write_sigio_thread : "
+ "read on socket failed, "
+ "err = %d\n", errno);
+ tmp = current_poll;
+ current_poll = next_poll;
+ next_poll = tmp;
+ respond_fd = sigio_private[1];
+ }
+ else {
+ respond_fd = write_sigio_fds[1];
+ fds->used--;
+ memmove(&fds->poll[i], &fds->poll[i + 1],
+ (fds->used - i) * sizeof(*fds->poll));
+ }
+
+ CATCH_EINTR(n = write(respond_fd, &c, sizeof(c)));
+ if (n != sizeof(c))
+ printk(UM_KERN_ERR "write_sigio_thread : "
+ "write on socket failed, err = %d\n",
+ errno);
+ }
+ }
+
+ return 0;
+}
+
+static int need_poll(struct pollfds *polls, int n)
+{
+ struct pollfd *new;
+
+ if (n <= polls->size)
+ return 0;
+
+ new = uml_kmalloc(n * sizeof(struct pollfd), UM_GFP_ATOMIC);
+ if (new == NULL) {
+ printk(UM_KERN_ERR "need_poll : failed to allocate new "
+ "pollfds\n");
+ return -ENOMEM;
+ }
+
+ memcpy(new, polls->poll, polls->used * sizeof(struct pollfd));
+ kfree(polls->poll);
+
+ polls->poll = new;
+ polls->size = n;
+ return 0;
+}
+
+/*
+ * Must be called with sigio_lock held, because it's needed by the marked
+ * critical section.
+ */
+static void update_thread(void)
+{
+ unsigned long flags;
+ int n;
+ char c;
+
+ flags = set_signals_trace(0);
+ CATCH_EINTR(n = write(sigio_private[0], &c, sizeof(c)));
+ if (n != sizeof(c)) {
+ printk(UM_KERN_ERR "update_thread : write failed, err = %d\n",
+ errno);
+ goto fail;
+ }
+
+ CATCH_EINTR(n = read(sigio_private[0], &c, sizeof(c)));
+ if (n != sizeof(c)) {
+ printk(UM_KERN_ERR "update_thread : read failed, err = %d\n",
+ errno);
+ goto fail;
+ }
+
+ set_signals_trace(flags);
+ return;
+ fail:
+ /* Critical section start */
+ if (write_sigio_pid != -1) {
+ os_kill_process(write_sigio_pid, 1);
+ free_stack(write_sigio_stack, 0);
+ }
+ write_sigio_pid = -1;
+ close(sigio_private[0]);
+ close(sigio_private[1]);
+ close(write_sigio_fds[0]);
+ close(write_sigio_fds[1]);
+ /* Critical section end */
+ set_signals_trace(flags);
+}
+
+int add_sigio_fd(int fd)
+{
+ struct pollfd *p;
+ int err = 0, i, n;
+
+ sigio_lock();
+ for (i = 0; i < all_sigio_fds.used; i++) {
+ if (all_sigio_fds.poll[i].fd == fd)
+ break;
+ }
+ if (i == all_sigio_fds.used)
+ goto out;
+
+ p = &all_sigio_fds.poll[i];
+
+ for (i = 0; i < current_poll.used; i++) {
+ if (current_poll.poll[i].fd == fd)
+ goto out;
+ }
+
+ n = current_poll.used;
+ err = need_poll(&next_poll, n + 1);
+ if (err)
+ goto out;
+
+ memcpy(next_poll.poll, current_poll.poll,
+ current_poll.used * sizeof(struct pollfd));
+ next_poll.poll[n] = *p;
+ next_poll.used = n + 1;
+ update_thread();
+ out:
+ sigio_unlock();
+ return err;
+}
+
+int ignore_sigio_fd(int fd)
+{
+ struct pollfd *p;
+ int err = 0, i, n = 0;
+
+ /*
+ * This is called from exitcalls elsewhere in UML - if
+ * sigio_cleanup has already run, then update_thread will hang
+ * or fail because the thread is no longer running.
+ */
+ if (write_sigio_pid == -1)
+ return -EIO;
+
+ sigio_lock();
+ for (i = 0; i < current_poll.used; i++) {
+ if (current_poll.poll[i].fd == fd)
+ break;
+ }
+ if (i == current_poll.used)
+ goto out;
+
+ err = need_poll(&next_poll, current_poll.used - 1);
+ if (err)
+ goto out;
+
+ for (i = 0; i < current_poll.used; i++) {
+ p = &current_poll.poll[i];
+ if (p->fd != fd)
+ next_poll.poll[n++] = *p;
+ }
+ next_poll.used = current_poll.used - 1;
+
+ update_thread();
+ out:
+ sigio_unlock();
+ return err;
+}
+
+static struct pollfd *setup_initial_poll(int fd)
+{
+ struct pollfd *p;
+
+ p = uml_kmalloc(sizeof(struct pollfd), UM_GFP_KERNEL);
+ if (p == NULL) {
+ printk(UM_KERN_ERR "setup_initial_poll : failed to allocate "
+ "poll\n");
+ return NULL;
+ }
+ *p = ((struct pollfd) { .fd = fd,
+ .events = POLLIN,
+ .revents = 0 });
+ return p;
+}
+
+static void write_sigio_workaround(void)
+{
+ struct pollfd *p;
+ int err;
+ int l_write_sigio_fds[2];
+ int l_sigio_private[2];
+ int l_write_sigio_pid;
+
+ /* We call this *tons* of times - and most ones we must just fail. */
+ sigio_lock();
+ l_write_sigio_pid = write_sigio_pid;
+ sigio_unlock();
+
+ if (l_write_sigio_pid != -1)
+ return;
+
+ err = os_pipe(l_write_sigio_fds, 1, 1);
+ if (err < 0) {
+ printk(UM_KERN_ERR "write_sigio_workaround - os_pipe 1 failed, "
+ "err = %d\n", -err);
+ return;
+ }
+ err = os_pipe(l_sigio_private, 1, 1);
+ if (err < 0) {
+ printk(UM_KERN_ERR "write_sigio_workaround - os_pipe 2 failed, "
+ "err = %d\n", -err);
+ goto out_close1;
+ }
+
+ p = setup_initial_poll(l_sigio_private[1]);
+ if (!p)
+ goto out_close2;
+
+ sigio_lock();
+
+ /*
+ * Did we race? Don't try to optimize this, please, it's not so likely
+ * to happen, and no more than once at the boot.
+ */
+ if (write_sigio_pid != -1)
+ goto out_free;
+
+ current_poll = ((struct pollfds) { .poll = p,
+ .used = 1,
+ .size = 1 });
+
+ if (write_sigio_irq(l_write_sigio_fds[0]))
+ goto out_clear_poll;
+
+ memcpy(write_sigio_fds, l_write_sigio_fds, sizeof(l_write_sigio_fds));
+ memcpy(sigio_private, l_sigio_private, sizeof(l_sigio_private));
+
+ write_sigio_pid = run_helper_thread(write_sigio_thread, NULL,
+ CLONE_FILES | CLONE_VM,
+ &write_sigio_stack);
+
+ if (write_sigio_pid < 0)
+ goto out_clear;
+
+ sigio_unlock();
+ return;
+
+out_clear:
+ write_sigio_pid = -1;
+ write_sigio_fds[0] = -1;
+ write_sigio_fds[1] = -1;
+ sigio_private[0] = -1;
+ sigio_private[1] = -1;
+out_clear_poll:
+ current_poll = ((struct pollfds) { .poll = NULL,
+ .size = 0,
+ .used = 0 });
+out_free:
+ sigio_unlock();
+ kfree(p);
+out_close2:
+ close(l_sigio_private[0]);
+ close(l_sigio_private[1]);
+out_close1:
+ close(l_write_sigio_fds[0]);
+ close(l_write_sigio_fds[1]);
+}
+
+void sigio_broken(int fd, int read)
+{
+ int err;
+
+ write_sigio_workaround();
+
+ sigio_lock();
+ err = need_poll(&all_sigio_fds, all_sigio_fds.used + 1);
+ if (err) {
+ printk(UM_KERN_ERR "maybe_sigio_broken - failed to add pollfd "
+ "for descriptor %d\n", fd);
+ goto out;
+ }
+
+ all_sigio_fds.poll[all_sigio_fds.used++] =
+ ((struct pollfd) { .fd = fd,
+ .events = read ? POLLIN : POLLOUT,
+ .revents = 0 });
+out:
+ sigio_unlock();
+}
+
+/* Changed during early boot */
+static int pty_output_sigio;
+static int pty_close_sigio;
+
+void maybe_sigio_broken(int fd, int read)
+{
+ if (!isatty(fd))
+ return;
+
+ if ((read || pty_output_sigio) && (!read || pty_close_sigio))
+ return;
+
+ sigio_broken(fd, read);
+}
+
+static void sigio_cleanup(void)
+{
+ if (write_sigio_pid == -1)
+ return;
+
+ os_kill_process(write_sigio_pid, 1);
+ free_stack(write_sigio_stack, 0);
+ write_sigio_pid = -1;
+}
+
+__uml_exitcall(sigio_cleanup);
+
+/* Used as a flag during SIGIO testing early in boot */
+static int got_sigio;
+
+static void __init handler(int sig)
+{
+ got_sigio = 1;
+}
+
+struct openpty_arg {
+ int master;
+ int slave;
+ int err;
+};
+
+static void openpty_cb(void *arg)
+{
+ struct openpty_arg *info = arg;
+
+ info->err = 0;
+ if (openpty(&info->master, &info->slave, NULL, NULL, NULL))
+ info->err = -errno;
+}
+
+static int async_pty(int master, int slave)
+{
+ int flags;
+
+ flags = fcntl(master, F_GETFL);
+ if (flags < 0)
+ return -errno;
+
+ if ((fcntl(master, F_SETFL, flags | O_NONBLOCK | O_ASYNC) < 0) ||
+ (fcntl(master, F_SETOWN, os_getpid()) < 0))
+ return -errno;
+
+ if ((fcntl(slave, F_SETFL, flags | O_NONBLOCK) < 0))
+ return -errno;
+
+ return 0;
+}
+
+static void __init check_one_sigio(void (*proc)(int, int))
+{
+ struct sigaction old, new;
+ struct openpty_arg pty = { .master = -1, .slave = -1 };
+ int master, slave, err;
+
+ initial_thread_cb(openpty_cb, &pty);
+ if (pty.err) {
+ printk(UM_KERN_ERR "check_one_sigio failed, errno = %d\n",
+ -pty.err);
+ return;
+ }
+
+ master = pty.master;
+ slave = pty.slave;
+
+ if ((master == -1) || (slave == -1)) {
+ printk(UM_KERN_ERR "check_one_sigio failed to allocate a "
+ "pty\n");
+ return;
+ }
+
+ /* Not now, but complain so we now where we failed. */
+ err = raw(master);
+ if (err < 0) {
+ printk(UM_KERN_ERR "check_one_sigio : raw failed, errno = %d\n",
+ -err);
+ return;
+ }
+
+ err = async_pty(master, slave);
+ if (err < 0) {
+ printk(UM_KERN_ERR "check_one_sigio : sigio_async failed, "
+ "err = %d\n", -err);
+ return;
+ }
+
+ if (sigaction(SIGIO, NULL, &old) < 0) {
+ printk(UM_KERN_ERR "check_one_sigio : sigaction 1 failed, "
+ "errno = %d\n", errno);
+ return;
+ }
+
+ new = old;
+ new.sa_handler = handler;
+ if (sigaction(SIGIO, &new, NULL) < 0) {
+ printk(UM_KERN_ERR "check_one_sigio : sigaction 2 failed, "
+ "errno = %d\n", errno);
+ return;
+ }
+
+ got_sigio = 0;
+ (*proc)(master, slave);
+
+ close(master);
+ close(slave);
+
+ if (sigaction(SIGIO, &old, NULL) < 0)
+ printk(UM_KERN_ERR "check_one_sigio : sigaction 3 failed, "
+ "errno = %d\n", errno);
+}
+
+static void tty_output(int master, int slave)
+{
+ int n;
+ char buf[512];
+
+ printk(UM_KERN_INFO "Checking that host ptys support output SIGIO...");
+
+ memset(buf, 0, sizeof(buf));
+
+ while (write(master, buf, sizeof(buf)) > 0) ;
+ if (errno != EAGAIN)
+ printk(UM_KERN_ERR "tty_output : write failed, errno = %d\n",
+ errno);
+ while (((n = read(slave, buf, sizeof(buf))) > 0) &&
+ !({ barrier(); got_sigio; }))
+ ;
+
+ if (got_sigio) {
+ printk(UM_KERN_CONT "Yes\n");
+ pty_output_sigio = 1;
+ } else if (n == -EAGAIN)
+ printk(UM_KERN_CONT "No, enabling workaround\n");
+ else
+ printk(UM_KERN_CONT "tty_output : read failed, err = %d\n", n);
+}
+
+static void tty_close(int master, int slave)
+{
+ printk(UM_KERN_INFO "Checking that host ptys support SIGIO on "
+ "close...");
+
+ close(slave);
+ if (got_sigio) {
+ printk(UM_KERN_CONT "Yes\n");
+ pty_close_sigio = 1;
+ } else
+ printk(UM_KERN_CONT "No, enabling workaround\n");
+}
+
+static void __init check_sigio(void)
+{
+ if ((access("/dev/ptmx", R_OK) < 0) &&
+ (access("/dev/ptyp0", R_OK) < 0)) {
+ printk(UM_KERN_WARNING "No pseudo-terminals available - "
+ "skipping pty SIGIO check\n");
+ return;
+ }
+ check_one_sigio(tty_output);
+ check_one_sigio(tty_close);
+}
+
+/* Here because it only does the SIGIO testing for now */
+void __init os_check_bugs(void)
+{
+ check_sigio();
+}
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