Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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();
+}