When reading only part of the id file, the ppos isn't tracked correctly.
This is taken care by simple_read_from_buffer.

Reading a single byte, and then the next byte would result EOF.

While this seems like not a big deal, this breaks abstractions that
reads information from files unbuffered. See for example
https://github.com/golang/go/issues/29399

This code was mentioned as problematic in
commit cd458ba9
("tracing: Do not (ab)use trace_seq in event_id_read()")

An example C code that show this bug is:

  #include <stdio.h>
  #include <stdint.h>

  #include <sys/types.h>
  #include <sys/stat.h>
  #include <fcntl.h>
  #include <unistd.h>

  int main(int argc, char **argv) {
    if (argc < 2)
      return 1;
    int fd = open(argv[1], O_RDONLY);
    char c;
    read(fd, &c, 1);
    printf("First  %c\n", c);
    read(fd, &c, 1);
    printf("Second %c\n", c);
  }

Then run with, e.g.

  sudo ./a.out /sys/kernel/debug/tracing/events/tcp/tcp_set_state/id

You'll notice you're getting the first character twice, instead of the
first two characters in the id file.

Link: http://lkml.kernel.org/r/20181231115837.4932-1-elazar@lightbitslabs.com

Cc: Orit Wasserman <orit.was@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 23725aee ("ftrace: provide an id file for each event")
Signed-off-by: Elazar Leibovich <elazar@lightbitslabs.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

When building a allmodconfig kernel for arm64 and boot that in qemu,
CONFIG_FTRACE_STARTUP_TEST gets enabled and that takes time so the
watchdog expires and prints out a message like this:
'watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:1]'
Depending on what the what test gets called from init_trace_selftests()
it stays minutes in the loop.
Rework so that function cond_resched() gets called in the
init_trace_selftests loop.

Link: http://lkml.kernel.org/r/20181130145622.26334-1-anders.roxell@linaro.orgCo-developed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Trivial fix to clean up an indentation issue, a whole chunk of code
has an extra space in the indentation.

Link: http://lkml.kernel.org/r/20181109132312.20994-1-colin.king@canonical.comSigned-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Automatic const char[] variables cause unnecessary code
generation. For example, the this_mod variable leads to

    3f04:       48 b8 5f 5f 74 68 69 73 5f 6d   movabs $0x6d5f736968745f5f,%rax # __this_m
    3f0e:       4c 8d 44 24 02                  lea    0x2(%rsp),%r8
    3f13:       48 8d 7c 24 10                  lea    0x10(%rsp),%rdi
    3f18:       48 89 44 24 02                  mov    %rax,0x2(%rsp)
    3f1d:       4c 89 e9                        mov    %r13,%rcx
    3f20:       b8 65 00 00 00                  mov    $0x65,%eax # e
    3f25:       48 c7 c2 00 00 00 00            mov    $0x0,%rdx
                        3f28: R_X86_64_32S      .rodata.str1.1+0x18d
    3f2c:       be 48 00 00 00                  mov    $0x48,%esi
    3f31:       c7 44 24 0a 6f 64 75 6c         movl   $0x6c75646f,0xa(%rsp) # odul
    3f39:       66 89 44 24 0e                  mov    %ax,0xe(%rsp)

i.e., the string gets built on the stack at runtime. Similar code can be
found for the other instances I'm replacing here. Putting the string
in .rodata reduces the combined .text+.rodata size and saves time and
stack space at runtime.

The simplest fix, and what I've done for the this_mod case, is to just
make the variable static.

However, for the "<faulted>" case where the same string is used twice,
that prevents the linker from merging those two literals, so instead use
a macro - that also keeps the two instances automatically in
sync (instead of only the compile-time strlen expression).

Finally, for the two runs of spaces, it turns out that the "build
these strings on the stack" is not the worst part of what gcc does -
it turns print_func_help_header_irq() into "if (tgid) { /*
print_event_info + five seq_printf calls */ } else { /* print
event_info + another five seq_printf */}". Taking inspiration from a
suggestion from Al Viro, use %.*s to make snprintf either stop after
the first two spaces or print the whole string. As a bonus, the
seq_printfs now fit on single lines (at least, they are not longer
than the existing ones in the function just above), making it easier
to see that the ascii art lines up.

x86-64 defconfig + CONFIG_FUNCTION_TRACER:

$ scripts/stackdelta /tmp/stackusage.{0,1}
./kernel/trace/ftrace.c ftrace_mod_callback     152     136     -16
./kernel/trace/trace.c  trace_default_header    56      32      -24
./kernel/trace/trace.c  tracing_mark_raw_write  96      72      -24
./kernel/trace/trace.c  tracing_mark_write      104     80      -24

bloat-o-meter

add/remove: 1/0 grow/shrink: 0/4 up/down: 14/-375 (-361)
Function                                     old     new   delta
this_mod                                       -      14     +14
ftrace_mod_callback                          577     542     -35
tracing_mark_raw_write                       444     374     -70
tracing_mark_write                           616     540     -76
trace_default_header                         600     406    -194

Link: http://lkml.kernel.org/r/20190320081757.6037-1-linux@rasmusvillemoes.dkSigned-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

It's not "Caculate".

Link: http://lkml.kernel.org/r/20181101154640.23162-1-tiny.windzz@gmail.comSigned-off-by: Yangtao Li <tiny.windzz@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Fix to make the type of $comm "string".  If we set the other type to $comm
argument, it shows meaningless value or wrong data. Currently probe events
allow us to set string array type (e.g. ":string[2]"), or other digit types
like x8 on $comm. But since clearly $comm is just a string data, it should
not be fetched by other types including array.

Link: http://lkml.kernel.org/r/155723736241.9149.14582064184468574539.stgit@devnote2

Cc: Andreas Ziegler <andreas.ziegler@fau.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 53305928 ("tracing: probeevent: Introduce new argument fetching code")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Do not accumulate strlen result on "ret" local variable, because
it is accumulated on "total" local variable for array case.

Link: http://lkml.kernel.org/r/155723735237.9149.3192150444705457531.stgit@devnote2

Fixes: 40b53b77 ("tracing: probeevent: Add array type support")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Since commit 53305928 ("tracing: probeevent: Introduce new
argument fetching code") dropped the $comm support from uprobe
events, this re-enables it.

For $comm support, uses strlcpy() instead of strncpy_from_user()
to copy current task's comm. Because it is in the kernel space,
strncpy_from_user() always fails to copy the comm.
This also uses strlen() instead of strnlen_user() to measure the
length of the comm.

Note that this uses -ECOMM as a token value to fetch the comm
string. If the user-space pointer points -ECOMM, it will be
translated to task->comm.

Link: http://lkml.kernel.org/r/155723734162.9149.4042756162201097965.stgit@devnote2

Fixes: 53305928 ("tracing: probeevent: Introduce new argument fetching code")
Reported-by: Andreas Ziegler <andreas.ziegler@fau.de>
Acked-by: Andreas Ziegler <andreas.ziegler@fau.de>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Nicolai Stange discovered[1] that if live kernel patching is enabled, and the
function tracer started tracing the same function that was patched, the
conversion of the fentry call site during the translation of going from
calling the live kernel patch trampoline to the iterator trampoline, would
have as slight window where it didn't call anything.

As live kernel patching depends on ftrace to always call its code (to
prevent the function being traced from being called, as it will redirect
it). This small window would allow the old buggy function to be called, and
this can cause undesirable results.

Nicolai submitted new patches[2] but these were controversial. As this is
similar to the static call emulation issues that came up a while ago[3].
But after some debate[4][5] adding a gap in the stack when entering the
breakpoint handler allows for pushing the return address onto the stack to
easily emulate a call.

[1] http://lkml.kernel.org/r/20180726104029.7736-1-nstange@suse.de
[2] http://lkml.kernel.org/r/20190427100639.15074-1-nstange@suse.de
[3] http://lkml.kernel.org/r/3cf04e113d71c9f8e4be95fb84a510f085aa4afa.1541711457.git.jpoimboe@redhat.com
[4] http://lkml.kernel.org/r/CAHk-=wh5OpheSU8Em_Q3Hg8qw_JtoijxOdPtHru6d+5K8TWM=A@mail.gmail.com
[5] http://lkml.kernel.org/r/CAHk-=wjvQxY4DvPrJ6haPgAa6b906h=MwZXO6G8OtiTGe=N7_w@mail.gmail.com

[
  Live kernel patching is not implemented on x86_32, thus the emulate
  calls are only for x86_64.
]

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Nicolai Stange <nstange@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: the arch/x86 maintainers <x86@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nayna Jain <nayna@linux.ibm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: "open list:KERNEL SELFTEST FRAMEWORK" <linux-kselftest@vger.kernel.org>
Cc: stable@vger.kernel.org
Fixes: b700e7f0 ("livepatch: kernel: add support for live patching")
Tested-by: Nicolai Stange <nstange@suse.de>
Reviewed-by: Nicolai Stange <nstange@suse.de>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[ Changed to only implement emulated calls for x86_64 ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

In order to allow breakpoints to emulate call instructions, they need to push
the return address onto the stack. The x86_64 int3 handler adds a small gap
to allow the stack to grow some. Use this gap to add the return address to
be able to emulate a call instruction at the breakpoint location.

These helper functions are added:

  int3_emulate_jmp(): changes the location of the regs->ip to return there.

 (The next two are only for x86_64)
  int3_emulate_push(): to push the address onto the gap in the stack
  int3_emulate_call(): push the return address and change regs->ip

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Nicolai Stange <nstange@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: the arch/x86 maintainers <x86@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nayna Jain <nayna@linux.ibm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: "open list:KERNEL SELFTEST FRAMEWORK" <linux-kselftest@vger.kernel.org>
Cc: stable@vger.kernel.org
Fixes: b700e7f0 ("livepatch: kernel: add support for live patching")
Tested-by: Nicolai Stange <nstange@suse.de>
Reviewed-by: Nicolai Stange <nstange@suse.de>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[ Modified to only work for x86_64 and added comment to int3_emulate_push() ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

To allow an int3 handler to emulate a call instruction, it must be able to
push a return address onto the stack. Add a gap to the stack to allow the
int3 handler to push the return address and change the return from int3 to
jump straight to the emulated called function target.

Link: http://lkml.kernel.org/r/20181130183917.hxmti5josgq4clti@treble
Link: http://lkml.kernel.org/r/20190502162133.GX2623@hirez.programming.kicks-ass.net

[
  Note, this is needed to allow Live Kernel Patching to not miss calling a
  patched function when tracing is enabled. -- Steven Rostedt
]

Cc: stable@vger.kernel.org
Fixes: b700e7f0 ("livepatch: kernel: add support for live patching")
Tested-by: Nicolai Stange <nstange@suse.de>
Reviewed-by: Nicolai Stange <nstange@suse.de>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

The 'ftdump' command in kdb is currently a bit of a last resort, at
least if you have lots of traces turned on.  It's going to print a
whole boatload of data out your serial port which is probably running
at 115200.  This could easily take many, many minutes.

Usually you're most interested in what's at the _end_ of the ftrace
buffer, AKA what happened most recently.  That means you've got to
wait the full time for the dump.  The 'ftdump' command does attempt to
help you a little bit by allowing you to skip a fixed number of
entries.  Unfortunately it provides no way for you to know how many
entries you should skip.

Let's do similar to python and allow you to use a negative number to
indicate that you want to skip all entries except the last few.  This
allows you to quickly see what you want.

Note that we also change the printout in ftdump to print the
(positive) number of entries actually skipped since that could be
helpful to know when you've specified a negative skip count.

Link: http://lkml.kernel.org/r/20190319171206.97107-3-dianders@chromium.orgSigned-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

These two new exported functions will be used in a future patch by
kdb_ftdump() to quickly skip all but the last few trace entries.

Link: http://lkml.kernel.org/r/20190319171206.97107-2-dianders@chromium.orgAcked-by: Daniel Thompson <daniel.thompson@linaro.org>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

The things skipped by kdb's "ftdump" command when you pass it a
parameter has always been entries, not lines.  The difference usually
doesn't matter but when the trace buffer has multi-line entries (like
a stack dump) it can matter.

Let's fix this both in the help text for ftdump and also in the local
variable names.

Link: http://lkml.kernel.org/r/20190319171206.97107-1-dianders@chromium.orgAcked-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

ftrace_graph_entry_stub() is defined in generic code, its prototype should
be in the generic header and not defined throughout architecture specific
code in order to use it.

Cc: Greentime Hu <green.hu@gmail.com>
Cc: Vincent Chen <deanbo422@gmail.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: linux-parisc@vger.kernel.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

The function_graph boot up self test emulates the tr->init() function in
order to add a wrapper around the function graph tracer entry code to test
for lock ups and such. But it does not emulate the tr->reset(), and just
calls the function_graph tracer tr->reset() function which will use its own
fgraph_ops to unregister function tracing with. As the fgraph_ops is
becoming more meaningful with the register_ftrace_graph() and
unregister_ftrace_graph() functions, the two need to be the same. The
emulated tr->init() uses its own fgraph_ops descriptor, which means the
unregister_ftrace_graph() must use the same ftrace_ops, which the selftest
currently does not do. By emulating the tr->reset() as the selftest does
with the tr->init() it will be able to pass the same fgraph_ops descriptor
to the unregister_ftrace_graph() as it did with the register_ftrace_graph().
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

The function_graph tracer has a stub function and its ops flag has the
FTRACE_OPS_FL_STUB set. As the function graph does not use the
ftrace_ops->func pointer but instead is called by a separate part of the
ftrace trampoline. The function_graph tracer still requires to pass in a
ftrace_ops that may also hold the hash of the functions to call. But there's
no reason to test that hash in the function tracing portion. Instead of
testing to see if we should call the stub function, just test if the ops has
FTRACE_OPS_FL_STUB set, and just skip it.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

The ASSIGN_OPS_HASH() macro was moved to fgraph.c where it was used, but for
some reason it wasn't removed from ftrace.c, as it is no longer referenced
there.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

When CONFIG_RCU_TRACE is not set, all these tracepoints are defined as
do-nothing macro.
We'd better make those inline functions that take proper arguments.

As RCU_TRACE() is defined as do-nothing marco as well when
CONFIG_RCU_TRACE is not set, so we can clean it up.

Link: http://lkml.kernel.org/r/1553602391-11926-4-git-send-email-laoar.shao@gmail.comReviewed-by: Paul E. McKenney <paulmck@linux.ibm.com>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

The tracepoints trace_sched_stat_{iowait, blocked, wait, sleep} should
be not exposed to user if CONFIG_SCHEDSTATS is not set.

Link: http://lkml.kernel.org/r/1553602391-11926-3-git-send-email-laoar.shao@gmail.comAcked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Sometimes we want to define a tracepoint as a do-nothing function.
So I introduce TRACE_EVENT_NOP, DECLARE_EVENT_CLASS_NOP and
DEFINE_EVENT_NOP for this kind of usage.

Link: http://lkml.kernel.org/r/1553602391-11926-2-git-send-email-laoar.shao@gmail.comSigned-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Add brief blurb about error_log to the 'Important files' section.

Link: http://lkml.kernel.org/r/c81e60f9aded495081231a32d2d1023c4d043a7a.1554072478.git.tom.zanussi@linux.intel.comAcked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Move most of the hist trigger extended error documentation to
ftrace.rst and expand on it to fully document tracing/error_log.

Link: http://lkml.kernel.org/r/c5d53c8f643ef6844d6ad8d0200c116936730b01.1554072478.git.tom.zanussi@linux.intel.comAcked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Add a testcase verifying basic tracing/error_log functionality.

Link: http://lkml.kernel.org/r/bf1c0d47a24672df945331462682d96296d1ab28.1554072478.git.tom.zanussi@linux.intel.comAcked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Error handling has been moved to the common tracing/error_log, so this
test is no longer valid.

Link: http://lkml.kernel.org/r/876a98b21018814cbf46f0a3605ae0906c51d53c.1554072478.git.tom.zanussi@linux.intel.comAcked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

The k/uprobe_sytax_errors test case defines a check_error() function
used to run a command and check the position of the caret in the
output.

This would be useful for other ftrace facilities too, so move it to
test.d/functions for use by anyone.  In the process, rename it to
ftrace_errlog_check() and parametrize it for general use.

Link: http://lkml.kernel.org/r/9f88080a06f1755811f69081926afe7e5cb53178.1554072478.git.tom.zanussi@linux.intel.comAcked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Add error_log testcase for error logs on probe events.
This tests most of error cases and checks the error position
is correct.

Link: http://lkml.kernel.org/r/63d695b74e0965988fa54ffa12beeb2c3475250d.1554072478.git.tom.zanussi@linux.intel.comAcked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
[tom.zanussi@linux.intel.com: changed >& redirection to 2>]
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

As each instance has their own error_log file, it makes more sense that the
instances show the errors of their own instead of all error_logs having the
same data. Make it that the errors show up in the instance error_log file
that the error happens in. If no instance trace_array is available, then
NULL can be passed in which will create the error in the top level instance
(the one at the top of the tracefs directory).
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Have the trace_array that associates the trace instance of the histogram
passed around to functions so that error handling can display the error
message in the proper instance.
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Pass in the trace_array that represents the instance the filter being
changed is in to create_event_filter(). This will allow for error messages
that happen when writing to the filter can be displayed in the proper
instance "error_log" file.

Note, for calls to create_filter() (that was also modified to support
create_event_filter()), that changes filters that do not exist in a instance
(for perf for example), NULL may be passed in, which means that there will
not be any message to log for that filter.
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Use tracing error_log with probe events for logging error more
precisely. This also makes all parse error returns -EINVAL
(except for -ENOMEM), because user can see better error message
in error_log file now.

Link: http://lkml.kernel.org/r/6a4d90e141d138040ea61f4776b991597077451e.1554072478.git.tom.zanussi@linux.intel.comAcked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Use tracing_log_err() from the new tracing error_log mechanism to send
filter parse errors to tracing/error_log.

With this change, users will be able to see filter errors by looking
at tracing/error_log.

The same errors will also be available in the filter file, as
expected.

Link: http://lkml.kernel.org/r/1d942c419941539a11d78a6810fc5740a99b2974.1554072478.git.tom.zanussi@linux.intel.comAcked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Replace hist_err() and hist_err_event() with tracing_log_err() from
the new tracing error_log mechanism.

Also add a couple related helper functions and remove most of the old
hist_err()-related code.

With this change, users no longer read the hist files for hist trigger
error information, but instead look at tracing/error_log for the same
information.

Link: http://lkml.kernel.org/r/c98f77a97c9715d18b623eeb5741057b330d5ac0.1554072478.git.tom.zanussi@linux.intel.comAcked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

In preparation for making use of the new trace error log, save the
subsystem and event name associated with the last hist command - it
will be passed as the location param in the event_log_err() calls.

Link: http://lkml.kernel.org/r/eb0fd1362be8f39facb86c83eecf441b7a5876f8.1554072478.git.tom.zanussi@linux.intel.comAcked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Introduce a new ftrace file, tracing/error_log, for ftrace commands to
log errors.  This is useful for allowing more complex commands such as
hist trigger and kprobe_event commands to point out specifically where
something may have gone wrong without forcing them to resort to more
ad hoc methods such as tacking error messages onto existing output
files.

To log a tracing error, call the event_log_err() function, passing it
a location string describing where it came from e.g. kprobe_events or
system:event, the command that caused the error, an array of static
error strings describing errors and an index within that array which
describes the specific error, along with the position to place the
error caret.

Reading the log displays the last (currently) 8 errors logged in the
following format:

  [timestamp] <loc>: error: <static error text>
    Command: <command that caused the error>
                      ^

Memory for the error log isn't allocated unless there has been a trace
event error, and the error log can be cleared and have its memory
freed by writing the empty string in truncation mode to it:

  # echo > tracing/error_log.

Link: http://lkml.kernel.org/r/0c2c82571fd38c5f3a88ca823627edff250e9416.1554072478.git.tom.zanussi@linux.intel.comAcked-by: Masami Hiramatsu <mhiramat@kernel.org>
Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Improvements-suggested-by: Steve Rostedt <rostedt@goodmis.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Ftrace provides the feature “instances” that provides the capability to
create multiple Ftrace ring buffers. However, currently these buffers
are created/accessed via userspace only. The kernel APIs providing these
features are not exported, hence cannot be used by other kernel
components.

This patch aims to extend this infrastructure to provide the
flexibility to create/log/remove/ enable-disable existing trace events
to these buffers from within the kernel.

Link: http://lkml.kernel.org/r/1553106531-3281-2-git-send-email-divya.indi@oracle.comSigned-off-by: Divya Indi <divya.indi@oracle.com>
Reviewed-by: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

'cnt' should be used to calculate ring buffer size rather than data->cnt

Link: http://lkml.kernel.org/r/1537704693-184237-1-git-send-email-yuehaibing@huawei.comSigned-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Pull KVM fixes from Paolo Bonzini:
 "A collection of x86 and ARM bugfixes, and some improvements to
  documentation.

  On top of this, a cleanup of kvm_para.h headers, which were exported
  by some architectures even though they not support KVM at all. This is
  responsible for all the Kbuild changes in the diffstat"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (28 commits)
  Documentation: kvm: clarify KVM_SET_USER_MEMORY_REGION
  KVM: doc: Document the life cycle of a VM and its resources
  KVM: selftests: complete IO before migrating guest state
  KVM: selftests: disable stack protector for all KVM tests
  KVM: selftests: explicitly disable PIE for tests
  KVM: selftests: assert on exit reason in CR4/cpuid sync test
  KVM: x86: update %rip after emulating IO
  x86/kvm/hyper-v: avoid spurious pending stimer on vCPU init
  kvm/x86: Move MSR_IA32_ARCH_CAPABILITIES to array emulated_msrs
  KVM: x86: Emulate MSR_IA32_ARCH_CAPABILITIES on AMD hosts
  kvm: don't redefine flags as something else
  kvm: mmu: Used range based flushing in slot_handle_level_range
  KVM: export <linux/kvm_para.h> and <asm/kvm_para.h> iif KVM is supported
  KVM: x86: remove check on nr_mmu_pages in kvm_arch_commit_memory_region()
  kvm: nVMX: Add a vmentry check for HOST_SYSENTER_ESP and HOST_SYSENTER_EIP fields
  KVM: SVM: Workaround errata#1096 (insn_len maybe zero on SMAP violation)
  KVM: Reject device ioctls from processes other than the VM's creator
  KVM: doc: Fix incorrect word ordering regarding supported use of APIs
  KVM: x86: fix handling of role.cr4_pae and rename it to 'gpte_size'
  KVM: nVMX: Do not inherit quadrant and invalid for the root shadow EPT
  ...

Pull x86 fixes from Thomas Gleixner:
 "A pile of x86 updates:

   - Prevent exceeding he valid physical address space in the /dev/mem
     limit checks.

   - Move all header content inside the header guard to prevent compile
     failures.

   - Fix the bogus __percpu annotation in this_cpu_has() which makes
     sparse very noisy.

   - Disable switch jump tables completely when retpolines are enabled.

   - Prevent leaking the trampoline address"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/realmode: Make set_real_mode_mem() static inline
  x86/cpufeature: Fix __percpu annotation in this_cpu_has()
  x86/mm: Don't exceed the valid physical address space
  x86/retpolines: Disable switch jump tables when retpolines are enabled
  x86/realmode: Don't leak the trampoline kernel address
  x86/boot: Fix incorrect ifdeffery scope
  x86/resctrl: Remove unused variable