Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 530 insertions, 0 deletions

diff --git a/drivers/s390/char/monreader.c b/drivers/s390/char/monreader.c
new file mode 100644
index 000000000..52bc0c95b
--- /dev/null
+++ b/drivers/s390/char/monreader.c
@@ -0,0 +1,530 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Character device driver for reading z/VM *MONITOR service records.
+ *
+ * Copyright IBM Corp. 2004, 2009
+ *
+ * Author: Gerald Schaefer <gerald.schaefer@de.ibm.com>
+ */
+
+#define pr_fmt(fmt) "monreader: " fmt
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/miscdevice.h>
+#include <linux/ctype.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <net/iucv/iucv.h>
+#include <linux/uaccess.h>
+#include <asm/machine.h>
+#include <asm/ebcdic.h>
+#include <asm/extmem.h>
+
+
+#define MON_COLLECT_SAMPLE 0x80
+#define MON_COLLECT_EVENT  0x40
+#define MON_SERVICE	   "*MONITOR"
+#define MON_IN_USE	   0x01
+#define MON_MSGLIM	   255
+
+static char mon_dcss_name[9] = "MONDCSS\0";
+
+struct mon_msg {
+	u32 pos;
+	u32 mca_offset;
+	struct iucv_message msg;
+	char msglim_reached;
+	char replied_msglim;
+};
+
+struct mon_private {
+	struct iucv_path *path;
+	struct mon_msg *msg_array[MON_MSGLIM];
+	unsigned int   write_index;
+	unsigned int   read_index;
+	atomic_t msglim_count;
+	atomic_t read_ready;
+	atomic_t iucv_connected;
+	atomic_t iucv_severed;
+};
+
+static unsigned long mon_in_use = 0;
+
+static unsigned long mon_dcss_start;
+static unsigned long mon_dcss_end;
+
+static DECLARE_WAIT_QUEUE_HEAD(mon_read_wait_queue);
+static DECLARE_WAIT_QUEUE_HEAD(mon_conn_wait_queue);
+
+static u8 user_data_connect[16] = {
+	/* Version code, must be 0x01 for shared mode */
+	0x01,
+	/* what to collect */
+	MON_COLLECT_SAMPLE | MON_COLLECT_EVENT,
+	/* DCSS name in EBCDIC, 8 bytes padded with blanks */
+	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+	0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+};
+
+static u8 user_data_sever[16] = {
+	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+};
+
+/******************************************************************************
+ *                             helper functions                               *
+ *****************************************************************************/
+/*
+ * Create the 8 bytes EBCDIC DCSS segment name from
+ * an ASCII name, incl. padding
+ */
+static void dcss_mkname(char *ascii_name, char *ebcdic_name)
+{
+	int i;
+
+	for (i = 0; i < 8; i++) {
+		if (ascii_name[i] == '\0')
+			break;
+		ebcdic_name[i] = toupper(ascii_name[i]);
+	}
+	for (; i < 8; i++)
+		ebcdic_name[i] = ' ';
+	ASCEBC(ebcdic_name, 8);
+}
+
+static inline unsigned long mon_mca_start(struct mon_msg *monmsg)
+{
+	return *(u32 *) &monmsg->msg.rmmsg;
+}
+
+static inline unsigned long mon_mca_end(struct mon_msg *monmsg)
+{
+	return *(u32 *) &monmsg->msg.rmmsg[4];
+}
+
+static inline u8 mon_mca_type(struct mon_msg *monmsg, u8 index)
+{
+	return *((u8 *)__va(mon_mca_start(monmsg)) + monmsg->mca_offset + index);
+}
+
+static inline u32 mon_mca_size(struct mon_msg *monmsg)
+{
+	return mon_mca_end(monmsg) - mon_mca_start(monmsg) + 1;
+}
+
+static inline u32 mon_rec_start(struct mon_msg *monmsg)
+{
+	return *((u32 *)(__va(mon_mca_start(monmsg)) + monmsg->mca_offset + 4));
+}
+
+static inline u32 mon_rec_end(struct mon_msg *monmsg)
+{
+	return *((u32 *)(__va(mon_mca_start(monmsg)) + monmsg->mca_offset + 8));
+}
+
+static int mon_check_mca(struct mon_msg *monmsg)
+{
+	if ((mon_rec_end(monmsg) <= mon_rec_start(monmsg)) ||
+	    (mon_rec_start(monmsg) < mon_dcss_start) ||
+	    (mon_rec_end(monmsg) > mon_dcss_end) ||
+	    (mon_mca_type(monmsg, 0) == 0) ||
+	    (mon_mca_size(monmsg) % 12 != 0) ||
+	    (mon_mca_end(monmsg) <= mon_mca_start(monmsg)) ||
+	    (mon_mca_end(monmsg) > mon_dcss_end) ||
+	    (mon_mca_start(monmsg) < mon_dcss_start) ||
+	    ((mon_mca_type(monmsg, 1) == 0) && (mon_mca_type(monmsg, 2) == 0)))
+		return -EINVAL;
+	return 0;
+}
+
+static int mon_send_reply(struct mon_msg *monmsg,
+			  struct mon_private *monpriv)
+{
+	int rc;
+
+	rc = iucv_message_reply(monpriv->path, &monmsg->msg,
+				IUCV_IPRMDATA, NULL, 0);
+	atomic_dec(&monpriv->msglim_count);
+	if (likely(!monmsg->msglim_reached)) {
+		monmsg->pos = 0;
+		monmsg->mca_offset = 0;
+		monpriv->read_index = (monpriv->read_index + 1) %
+				      MON_MSGLIM;
+		atomic_dec(&monpriv->read_ready);
+	} else
+		monmsg->replied_msglim = 1;
+	if (rc) {
+		pr_err("Reading monitor data failed with rc=%i\n", rc);
+		return -EIO;
+	}
+	return 0;
+}
+
+static void mon_free_mem(struct mon_private *monpriv)
+{
+	int i;
+
+	for (i = 0; i < MON_MSGLIM; i++)
+		kfree(monpriv->msg_array[i]);
+	kfree(monpriv);
+}
+
+static struct mon_private *mon_alloc_mem(void)
+{
+	int i;
+	struct mon_private *monpriv;
+
+	monpriv = kzalloc_obj(struct mon_private);
+	if (!monpriv)
+		return NULL;
+	for (i = 0; i < MON_MSGLIM; i++) {
+		monpriv->msg_array[i] = kzalloc_obj(struct mon_msg);
+		if (!monpriv->msg_array[i]) {
+			mon_free_mem(monpriv);
+			return NULL;
+		}
+	}
+	return monpriv;
+}
+
+static inline void mon_next_mca(struct mon_msg *monmsg)
+{
+	if (likely((mon_mca_size(monmsg) - monmsg->mca_offset) == 12))
+		return;
+	monmsg->mca_offset += 12;
+	monmsg->pos = 0;
+}
+
+static struct mon_msg *mon_next_message(struct mon_private *monpriv)
+{
+	struct mon_msg *monmsg;
+
+	if (!atomic_read(&monpriv->read_ready))
+		return NULL;
+	monmsg = monpriv->msg_array[monpriv->read_index];
+	if (unlikely(monmsg->replied_msglim)) {
+		monmsg->replied_msglim = 0;
+		monmsg->msglim_reached = 0;
+		monmsg->pos = 0;
+		monmsg->mca_offset = 0;
+		monpriv->read_index = (monpriv->read_index + 1) %
+				      MON_MSGLIM;
+		atomic_dec(&monpriv->read_ready);
+		return ERR_PTR(-EOVERFLOW);
+	}
+	return monmsg;
+}
+
+
+/******************************************************************************
+ *                               IUCV handler                                 *
+ *****************************************************************************/
+static void mon_iucv_path_complete(struct iucv_path *path, u8 *ipuser)
+{
+	struct mon_private *monpriv = path->private;
+
+	atomic_set(&monpriv->iucv_connected, 1);
+	wake_up(&mon_conn_wait_queue);
+}
+
+static void mon_iucv_path_severed(struct iucv_path *path, u8 *ipuser)
+{
+	struct mon_private *monpriv = path->private;
+
+	pr_err("z/VM *MONITOR system service disconnected with rc=%i\n",
+	       ipuser[0]);
+	iucv_path_sever(path, NULL);
+	atomic_set(&monpriv->iucv_severed, 1);
+	wake_up(&mon_conn_wait_queue);
+	wake_up_interruptible(&mon_read_wait_queue);
+}
+
+static void mon_iucv_message_pending(struct iucv_path *path,
+				     struct iucv_message *msg)
+{
+	struct mon_private *monpriv = path->private;
+
+	memcpy(&monpriv->msg_array[monpriv->write_index]->msg,
+	       msg, sizeof(*msg));
+	if (atomic_inc_return(&monpriv->msglim_count) == MON_MSGLIM) {
+		pr_warn("The read queue for monitor data is full\n");
+		monpriv->msg_array[monpriv->write_index]->msglim_reached = 1;
+	}
+	monpriv->write_index = (monpriv->write_index + 1) % MON_MSGLIM;
+	atomic_inc(&monpriv->read_ready);
+	wake_up_interruptible(&mon_read_wait_queue);
+}
+
+static struct iucv_handler monreader_iucv_handler = {
+	.path_complete	 = mon_iucv_path_complete,
+	.path_severed	 = mon_iucv_path_severed,
+	.message_pending = mon_iucv_message_pending,
+};
+
+/******************************************************************************
+ *                               file operations                              *
+ *****************************************************************************/
+static int mon_open(struct inode *inode, struct file *filp)
+{
+	struct mon_private *monpriv;
+	int rc;
+
+	/*
+	 * only one user allowed
+	 */
+	rc = -EBUSY;
+	if (test_and_set_bit(MON_IN_USE, &mon_in_use))
+		goto out;
+
+	rc = -ENOMEM;
+	monpriv = mon_alloc_mem();
+	if (!monpriv)
+		goto out_use;
+
+	/*
+	 * Connect to *MONITOR service
+	 */
+	monpriv->path = iucv_path_alloc(MON_MSGLIM, IUCV_IPRMDATA, GFP_KERNEL);
+	if (!monpriv->path)
+		goto out_priv;
+	rc = iucv_path_connect(monpriv->path, &monreader_iucv_handler,
+			       MON_SERVICE, NULL, user_data_connect, monpriv);
+	if (rc) {
+		pr_err("Connecting to the z/VM *MONITOR system service "
+		       "failed with rc=%i\n", rc);
+		rc = -EIO;
+		goto out_path;
+	}
+	/*
+	 * Wait for connection confirmation
+	 */
+	wait_event(mon_conn_wait_queue,
+		   atomic_read(&monpriv->iucv_connected) ||
+		   atomic_read(&monpriv->iucv_severed));
+	if (atomic_read(&monpriv->iucv_severed)) {
+		atomic_set(&monpriv->iucv_severed, 0);
+		atomic_set(&monpriv->iucv_connected, 0);
+		rc = -EIO;
+		goto out_path;
+	}
+	filp->private_data = monpriv;
+	return nonseekable_open(inode, filp);
+
+out_path:
+	iucv_path_free(monpriv->path);
+out_priv:
+	mon_free_mem(monpriv);
+out_use:
+	clear_bit(MON_IN_USE, &mon_in_use);
+out:
+	return rc;
+}
+
+static int mon_close(struct inode *inode, struct file *filp)
+{
+	int rc, i;
+	struct mon_private *monpriv = filp->private_data;
+
+	/*
+	 * Close IUCV connection and unregister
+	 */
+	if (monpriv->path) {
+		rc = iucv_path_sever(monpriv->path, user_data_sever);
+		if (rc)
+			pr_warn("Disconnecting the z/VM *MONITOR system service failed with rc=%i\n",
+				rc);
+		iucv_path_free(monpriv->path);
+	}
+
+	atomic_set(&monpriv->iucv_severed, 0);
+	atomic_set(&monpriv->iucv_connected, 0);
+	atomic_set(&monpriv->read_ready, 0);
+	atomic_set(&monpriv->msglim_count, 0);
+	monpriv->write_index  = 0;
+	monpriv->read_index   = 0;
+
+	for (i = 0; i < MON_MSGLIM; i++)
+		kfree(monpriv->msg_array[i]);
+	kfree(monpriv);
+	clear_bit(MON_IN_USE, &mon_in_use);
+	return 0;
+}
+
+static ssize_t mon_read(struct file *filp, char __user *data,
+			size_t count, loff_t *ppos)
+{
+	struct mon_private *monpriv = filp->private_data;
+	struct mon_msg *monmsg;
+	int ret;
+	u32 mce_start;
+
+	monmsg = mon_next_message(monpriv);
+	if (IS_ERR(monmsg))
+		return PTR_ERR(monmsg);
+
+	if (!monmsg) {
+		if (filp->f_flags & O_NONBLOCK)
+			return -EAGAIN;
+		ret = wait_event_interruptible(mon_read_wait_queue,
+					atomic_read(&monpriv->read_ready) ||
+					atomic_read(&monpriv->iucv_severed));
+		if (ret)
+			return ret;
+		if (unlikely(atomic_read(&monpriv->iucv_severed)))
+			return -EIO;
+		monmsg = monpriv->msg_array[monpriv->read_index];
+	}
+
+	if (!monmsg->pos)
+		monmsg->pos = mon_mca_start(monmsg) + monmsg->mca_offset;
+	if (mon_check_mca(monmsg))
+		goto reply;
+
+	/* read monitor control element (12 bytes) first */
+	mce_start = mon_mca_start(monmsg) + monmsg->mca_offset;
+	if ((monmsg->pos >= mce_start) && (monmsg->pos < mce_start + 12)) {
+		count = min(count, (size_t) mce_start + 12 - monmsg->pos);
+		ret = copy_to_user(data, __va(monmsg->pos), count);
+		if (ret)
+			return -EFAULT;
+		monmsg->pos += count;
+		if (monmsg->pos == mce_start + 12)
+			monmsg->pos = mon_rec_start(monmsg);
+		goto out_copy;
+	}
+
+	/* read records */
+	if (monmsg->pos <= mon_rec_end(monmsg)) {
+		count = min(count, (size_t) mon_rec_end(monmsg) - monmsg->pos
+					    + 1);
+		ret = copy_to_user(data, __va(monmsg->pos), count);
+		if (ret)
+			return -EFAULT;
+		monmsg->pos += count;
+		if (monmsg->pos > mon_rec_end(monmsg))
+			mon_next_mca(monmsg);
+		goto out_copy;
+	}
+reply:
+	ret = mon_send_reply(monmsg, monpriv);
+	return ret;
+
+out_copy:
+	*ppos += count;
+	return count;
+}
+
+static __poll_t mon_poll(struct file *filp, struct poll_table_struct *p)
+{
+	struct mon_private *monpriv = filp->private_data;
+
+	poll_wait(filp, &mon_read_wait_queue, p);
+	if (unlikely(atomic_read(&monpriv->iucv_severed)))
+		return EPOLLERR;
+	if (atomic_read(&monpriv->read_ready))
+		return EPOLLIN | EPOLLRDNORM;
+	return 0;
+}
+
+static const struct file_operations mon_fops = {
+	.owner   = THIS_MODULE,
+	.open    = &mon_open,
+	.release = &mon_close,
+	.read    = &mon_read,
+	.poll    = &mon_poll,
+	.llseek  = noop_llseek,
+};
+
+static struct miscdevice mon_dev = {
+	.name       = "monreader",
+	.fops       = &mon_fops,
+	.minor      = MISC_DYNAMIC_MINOR,
+};
+
+/******************************************************************************
+ *                              module init/exit                              *
+ *****************************************************************************/
+static int __init mon_init(void)
+{
+	int rc;
+
+	if (!machine_is_vm()) {
+		pr_err("The z/VM *MONITOR record device driver cannot be "
+		       "loaded without z/VM\n");
+		return -ENODEV;
+	}
+
+	/*
+	 * Register with IUCV and connect to *MONITOR service
+	 */
+	rc = iucv_register(&monreader_iucv_handler, 1);
+	if (rc) {
+		pr_err("The z/VM *MONITOR record device driver failed to "
+		       "register with IUCV\n");
+		return rc;
+	}
+
+	rc = segment_type(mon_dcss_name);
+	if (rc < 0) {
+		segment_warning(rc, mon_dcss_name);
+		goto out_iucv;
+	}
+	if (rc != SEG_TYPE_SC) {
+		pr_err("The specified *MONITOR DCSS %s does not have the "
+		       "required type SC\n", mon_dcss_name);
+		rc = -EINVAL;
+		goto out_iucv;
+	}
+
+	rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
+			  &mon_dcss_start, &mon_dcss_end);
+	if (rc < 0) {
+		segment_warning(rc, mon_dcss_name);
+		rc = -EINVAL;
+		goto out_iucv;
+	}
+	dcss_mkname(mon_dcss_name, &user_data_connect[8]);
+
+	/*
+	 * misc_register() has to be the last action in module_init(), because
+	 * file operations will be available right after this.
+	 */
+	rc = misc_register(&mon_dev);
+	if (rc < 0 )
+		goto out;
+	return 0;
+
+out:
+	segment_unload(mon_dcss_name);
+out_iucv:
+	iucv_unregister(&monreader_iucv_handler, 1);
+	return rc;
+}
+
+static void __exit mon_exit(void)
+{
+	segment_unload(mon_dcss_name);
+	misc_deregister(&mon_dev);
+	iucv_unregister(&monreader_iucv_handler, 1);
+	return;
+}
+
+
+module_init(mon_init);
+module_exit(mon_exit);
+
+module_param_string(mondcss, mon_dcss_name, 9, 0444);
+MODULE_PARM_DESC(mondcss, "Name of DCSS segment to be used for *MONITOR "
+		 "service, max. 8 chars. Default is MONDCSS");
+
+MODULE_AUTHOR("Gerald Schaefer <geraldsc@de.ibm.com>");
+MODULE_DESCRIPTION("Character device driver for reading z/VM "
+		   "monitor service records.");
+MODULE_LICENSE("GPL");