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, 423 insertions, 0 deletions

diff --git a/Documentation/admin-guide/java.rst b/Documentation/admin-guide/java.rst
new file mode 100644
index 000000000..8744e272e
--- /dev/null
+++ b/Documentation/admin-guide/java.rst
@@ -0,0 +1,423 @@
+Java(tm) Binary Kernel Support for Linux v1.03
+----------------------------------------------
+
+Linux beats them ALL! While all other OS's are TALKING about direct
+support of Java Binaries in the OS, Linux is doing it!
+
+You can execute Java applications and Java Applets just like any
+other program after you have done the following:
+
+1) You MUST FIRST install the Java Developers Kit for Linux.
+   The Java on Linux HOWTO gives the details on getting and
+   installing this. This HOWTO can be found at:
+
+	ftp://sunsite.unc.edu/pub/Linux/docs/HOWTO/Java-HOWTO
+
+   You should also set up a reasonable CLASSPATH environment
+   variable to use Java applications that make use of any
+   nonstandard classes (not included in the same directory
+   as the application itself).
+
+2) You have to compile BINFMT_MISC either as a module or into
+   the kernel (``CONFIG_BINFMT_MISC``) and set it up properly.
+   If you choose to compile it as a module, you will have
+   to insert it manually with modprobe/insmod, as kmod
+   cannot easily be supported with binfmt_misc.
+   Read the file 'binfmt_misc.txt' in this directory to know
+   more about the configuration process.
+
+3) Add the following configuration items to binfmt_misc
+   (you should really have read ``binfmt_misc.txt`` now):
+   support for Java applications::
+
+     ':Java:M::\xca\xfe\xba\xbe::/usr/local/bin/javawrapper:'
+
+   support for executable Jar files::
+
+     ':ExecutableJAR:E::jar::/usr/local/bin/jarwrapper:'
+
+   support for Java Applets::
+
+     ':Applet:E::html::/usr/bin/appletviewer:'
+
+   or the following, if you want to be more selective::
+
+     ':Applet:M::<!--applet::/usr/bin/appletviewer:'
+
+   Of course you have to fix the path names. The path/file names given in this
+   document match the Debian 2.1 system. (i.e. jdk installed in ``/usr``,
+   custom wrappers from this document in ``/usr/local``)
+
+   Note, that for the more selective applet support you have to modify
+   existing html-files to contain ``<!--applet-->`` in the first line
+   (``<`` has to be the first character!) to let this work!
+
+   For the compiled Java programs you need a wrapper script like the
+   following (this is because Java is broken in case of the filename
+   handling), again fix the path names, both in the script and in the
+   above given configuration string.
+
+   You, too, need the little program after the script. Compile like::
+
+	gcc -O2 -o javaclassname javaclassname.c
+
+   and stick it to ``/usr/local/bin``.
+
+   Both the javawrapper shellscript and the javaclassname program
+   were supplied by Colin J. Watson <cjw44@cam.ac.uk>.
+
+Javawrapper shell script:
+
+.. code-block:: sh
+
+  #!/bin/bash
+  # /usr/local/bin/javawrapper - the wrapper for binfmt_misc/java
+
+  if [ -z "$1" ]; then
+	exec 1>&2
+	echo Usage: $0 class-file
+	exit 1
+  fi
+
+  CLASS=$1
+  FQCLASS=`/usr/local/bin/javaclassname $1`
+  FQCLASSN=`echo $FQCLASS | sed -e 's/^.*\.\([^.]*\)$/\1/'`
+  FQCLASSP=`echo $FQCLASS | sed -e 's-\.-/-g' -e 's-^[^/]*$--' -e 's-/[^/]*$--'`
+
+  # for example:
+  # CLASS=Test.class
+  # FQCLASS=foo.bar.Test
+  # FQCLASSN=Test
+  # FQCLASSP=foo/bar
+
+  unset CLASSBASE
+
+  declare -i LINKLEVEL=0
+
+  while :; do
+	if [ "`basename $CLASS .class`" == "$FQCLASSN" ]; then
+		# See if this directory works straight off
+		cd -L `dirname $CLASS`
+		CLASSDIR=$PWD
+		cd $OLDPWD
+		if echo $CLASSDIR | grep -q "$FQCLASSP$"; then
+			CLASSBASE=`echo $CLASSDIR | sed -e "s.$FQCLASSP$.."`
+			break;
+		fi
+		# Try dereferencing the directory name
+		cd -P `dirname $CLASS`
+		CLASSDIR=$PWD
+		cd $OLDPWD
+		if echo $CLASSDIR | grep -q "$FQCLASSP$"; then
+			CLASSBASE=`echo $CLASSDIR | sed -e "s.$FQCLASSP$.."`
+			break;
+		fi
+		# If no other possible filename exists
+		if [ ! -L $CLASS ]; then
+			exec 1>&2
+			echo $0:
+			echo "  $CLASS should be in a" \
+			     "directory tree called $FQCLASSP"
+			exit 1
+		fi
+	fi
+	if [ ! -L $CLASS ]; then break; fi
+	# Go down one more level of symbolic links
+	let LINKLEVEL+=1
+	if [ $LINKLEVEL -gt 5 ]; then
+		exec 1>&2
+		echo $0:
+		echo "  Too many symbolic links encountered"
+		exit 1
+	fi
+	CLASS=`ls --color=no -l $CLASS | sed -e 's/^.* \([^ ]*\)$/\1/'`
+  done
+
+  if [ -z "$CLASSBASE" ]; then
+	if [ -z "$FQCLASSP" ]; then
+		GOODNAME=$FQCLASSN.class
+	else
+		GOODNAME=$FQCLASSP/$FQCLASSN.class
+	fi
+	exec 1>&2
+	echo $0:
+	echo "  $FQCLASS should be in a file called $GOODNAME"
+	exit 1
+  fi
+
+  if ! echo $CLASSPATH | grep -q "^\(.*:\)*$CLASSBASE\(:.*\)*"; then
+	# class is not in CLASSPATH, so prepend dir of class to CLASSPATH
+	if [ -z "${CLASSPATH}" ] ; then
+		export CLASSPATH=$CLASSBASE
+	else
+		export CLASSPATH=$CLASSBASE:$CLASSPATH
+	fi
+  fi
+
+  shift
+  /usr/bin/java $FQCLASS "$@"
+
+javaclassname.c:
+
+.. code-block:: c
+
+  /* javaclassname.c
+   *
+   * Extracts the class name from a Java class file; intended for use in a Java
+   * wrapper of the type supported by the binfmt_misc option in the Linux kernel.
+   *
+   * Copyright (C) 1999 Colin J. Watson <cjw44@cam.ac.uk>.
+   *
+   * This program is free software; you can redistribute it and/or modify
+   * it under the terms of the GNU General Public License as published by
+   * the Free Software Foundation; either version 2 of the License, or
+   * (at your option) any later version.
+   *
+   * This program is distributed in the hope that it will be useful,
+   * but WITHOUT ANY WARRANTY; without even the implied warranty of
+   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   * GNU General Public License for more details.
+   *
+   * You should have received a copy of the GNU General Public License
+   * along with this program; if not, write to the Free Software
+   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+   */
+
+  #include <stdlib.h>
+  #include <stdio.h>
+  #include <stdarg.h>
+  #include <sys/types.h>
+
+  /* From Sun's Java VM Specification, as tag entries in the constant pool. */
+
+  #define CP_UTF8 1
+  #define CP_INTEGER 3
+  #define CP_FLOAT 4
+  #define CP_LONG 5
+  #define CP_DOUBLE 6
+  #define CP_CLASS 7
+  #define CP_STRING 8
+  #define CP_FIELDREF 9
+  #define CP_METHODREF 10
+  #define CP_INTERFACEMETHODREF 11
+  #define CP_NAMEANDTYPE 12
+  #define CP_METHODHANDLE 15
+  #define CP_METHODTYPE 16
+  #define CP_INVOKEDYNAMIC 18
+
+  /* Define some commonly used error messages */
+
+  #define seek_error() error("%s: Cannot seek\n", program)
+  #define corrupt_error() error("%s: Class file corrupt\n", program)
+  #define eof_error() error("%s: Unexpected end of file\n", program)
+  #define utf8_error() error("%s: Only ASCII 1-255 supported\n", program);
+
+  char *program;
+
+  long *pool;
+
+  u_int8_t read_8(FILE *classfile);
+  u_int16_t read_16(FILE *classfile);
+  void skip_constant(FILE *classfile, u_int16_t *cur);
+  void error(const char *format, ...);
+  int main(int argc, char **argv);
+
+  /* Reads in an unsigned 8-bit integer. */
+  u_int8_t read_8(FILE *classfile)
+  {
+	int b = fgetc(classfile);
+	if(b == EOF)
+		eof_error();
+	return (u_int8_t)b;
+  }
+
+  /* Reads in an unsigned 16-bit integer. */
+  u_int16_t read_16(FILE *classfile)
+  {
+	int b1, b2;
+	b1 = fgetc(classfile);
+	if(b1 == EOF)
+		eof_error();
+	b2 = fgetc(classfile);
+	if(b2 == EOF)
+		eof_error();
+	return (u_int16_t)((b1 << 8) | b2);
+  }
+
+  /* Reads in a value from the constant pool. */
+  void skip_constant(FILE *classfile, u_int16_t *cur)
+  {
+	u_int16_t len;
+	int seekerr = 1;
+	pool[*cur] = ftell(classfile);
+	switch(read_8(classfile))
+	{
+	case CP_UTF8:
+		len = read_16(classfile);
+		seekerr = fseek(classfile, len, SEEK_CUR);
+		break;
+	case CP_CLASS:
+	case CP_STRING:
+	case CP_METHODTYPE:
+		seekerr = fseek(classfile, 2, SEEK_CUR);
+		break;
+	case CP_METHODHANDLE:
+		seekerr = fseek(classfile, 3, SEEK_CUR);
+		break;
+	case CP_INTEGER:
+	case CP_FLOAT:
+	case CP_FIELDREF:
+	case CP_METHODREF:
+	case CP_INTERFACEMETHODREF:
+	case CP_NAMEANDTYPE:
+	case CP_INVOKEDYNAMIC:
+		seekerr = fseek(classfile, 4, SEEK_CUR);
+		break;
+	case CP_LONG:
+	case CP_DOUBLE:
+		seekerr = fseek(classfile, 8, SEEK_CUR);
+		++(*cur);
+		break;
+	default:
+		corrupt_error();
+	}
+	if(seekerr)
+		seek_error();
+  }
+
+  void error(const char *format, ...)
+  {
+	va_list ap;
+	va_start(ap, format);
+	vfprintf(stderr, format, ap);
+	va_end(ap);
+	exit(1);
+  }
+
+  int main(int argc, char **argv)
+  {
+	FILE *classfile;
+	u_int16_t cp_count, i, this_class, classinfo_ptr;
+	u_int8_t length;
+
+	program = argv[0];
+
+	if(!argv[1])
+		error("%s: Missing input file\n", program);
+	classfile = fopen(argv[1], "rb");
+	if(!classfile)
+		error("%s: Error opening %s\n", program, argv[1]);
+
+	if(fseek(classfile, 8, SEEK_SET))  /* skip magic and version numbers */
+		seek_error();
+	cp_count = read_16(classfile);
+	pool = calloc(cp_count, sizeof(long));
+	if(!pool)
+		error("%s: Out of memory for constant pool\n", program);
+
+	for(i = 1; i < cp_count; ++i)
+		skip_constant(classfile, &i);
+	if(fseek(classfile, 2, SEEK_CUR))	/* skip access flags */
+		seek_error();
+
+	this_class = read_16(classfile);
+	if(this_class < 1 || this_class >= cp_count)
+		corrupt_error();
+	if(!pool[this_class] || pool[this_class] == -1)
+		corrupt_error();
+	if(fseek(classfile, pool[this_class] + 1, SEEK_SET))
+		seek_error();
+
+	classinfo_ptr = read_16(classfile);
+	if(classinfo_ptr < 1 || classinfo_ptr >= cp_count)
+		corrupt_error();
+	if(!pool[classinfo_ptr] || pool[classinfo_ptr] == -1)
+		corrupt_error();
+	if(fseek(classfile, pool[classinfo_ptr] + 1, SEEK_SET))
+		seek_error();
+
+	length = read_16(classfile);
+	for(i = 0; i < length; ++i)
+	{
+		u_int8_t x = read_8(classfile);
+		if((x & 0x80) || !x)
+		{
+			if((x & 0xE0) == 0xC0)
+			{
+				u_int8_t y = read_8(classfile);
+				if((y & 0xC0) == 0x80)
+				{
+					int c = ((x & 0x1f) << 6) + (y & 0x3f);
+					if(c) putchar(c);
+					else utf8_error();
+				}
+				else utf8_error();
+			}
+			else utf8_error();
+		}
+		else if(x == '/') putchar('.');
+		else putchar(x);
+	}
+	putchar('\n');
+	free(pool);
+	fclose(classfile);
+	return 0;
+  }
+
+jarwrapper::
+
+  #!/bin/bash
+  # /usr/local/java/bin/jarwrapper - the wrapper for binfmt_misc/jar
+
+  java -jar $1
+
+
+Now simply ``chmod +x`` the ``.class``, ``.jar`` and/or ``.html`` files you
+want to execute.
+
+To add a Java program to your path best put a symbolic link to the main
+.class file into /usr/bin (or another place you like) omitting the .class
+extension. The directory containing the original .class file will be
+added to your CLASSPATH during execution.
+
+
+To test your new setup, enter in the following simple Java app, and name
+it "HelloWorld.java":
+
+.. code-block:: java
+
+	class HelloWorld {
+		public static void main(String args[]) {
+			System.out.println("Hello World!");
+		}
+	}
+
+Now compile the application with::
+
+	javac HelloWorld.java
+
+Set the executable permissions of the binary file, with::
+
+	chmod 755 HelloWorld.class
+
+And then execute it::
+
+	./HelloWorld.class
+
+
+To execute Java Jar files, simple chmod the ``*.jar`` files to include
+the execution bit, then just do::
+
+       ./Application.jar
+
+
+To execute Java Applets, simple chmod the ``*.html`` files to include
+the execution bit, then just do::
+
+	./Applet.html
+
+
+originally by Brian A. Lantz, brian@lantz.com
+heavily edited for binfmt_misc by Richard Günther
+new scripts by Colin J. Watson <cjw44@cam.ac.uk>
+added executable Jar file support by Kurt Huwig <kurt@iku-netz.de>