Most arch syscall_get_nr() implementations returns -1 if the syscall
number is not valid. Accessing the bit field without a check might
result in a kernel oops (at least I saw it on s390 for ftrace selftest).
Before this change, this problem did not occur, because the invalid
syscall number (-1) caused syscall_nr_to_meta() to return NULL.
There are at least two scenarios where syscall_get_nr() can return -1:
1. For example, ptrace stores an invalid syscall number, and thus,
tracing code resets it.
(see do_syscall_trace_enter in arch/s390/kernel/ptrace.c)
2. The syscall_regfunc() (kernel/tracepoint.c) sets the
TIF_SYSCALL_FTRACE (now: TIF_SYSCALL_TRACEPOINT) flag for all threads
which include kernel threads.
However, the ftrace selftest triggers a kernel oops when testing
syscall trace points:
- The kernel thread is started as ususal (do_fork()),
- tracing code sets TIF_SYSCALL_FTRACE,
- the ret_from_fork() function is triggered and starts
ftrace_syscall_exit() with an invalid syscall number.
To avoid these scenarios, I suggest to check the syscall_nr.
For instance, the ftrace selftest fails for s390 (with config option
CONFIG_FTRACE_SYSCALLS set) and produces the following kernel oops.
Unable to handle kernel pointer dereference at virtual kernel address 2000000000
Oops: 0038 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 Not tainted 2.6.31-rc6-next-20090819-dirty #18
Process kthreadd (pid: 818, task: 000000003ea207e8, ksp: 000000003e813eb8)
Krnl PSW : 0704100180000000 00000000000ea54c (ftrace_syscall_exit+0x58/0xdc)
R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:0 CC:1 PM:0 EA:3
Krnl GPRS: 0000000000000000 00000000000e0000 ffffffffffffffff 20000000008c2650
0000000000000007 0000000000000000 0000000000000000 0000000000000000
0000000000000000 0000000000000000 ffffffffffffffff 000000003e813d78
000000003e813f58 0000000000505ba8 000000003e813e18 000000003e813d78
Krnl Code: 00000000000ea540: e330d0000008 ag %r3,0(%r13)
00000000000ea546: a7480007 lhi %r4,7
00000000000ea54a: 1442 nr %r4,%r2
>00000000000ea54c: e31030000090 llgc %r1,0(%r3)
00000000000ea552: 5410d008 n %r1,8(%r13)
00000000000ea556: 8a104000 sra %r1,0(%r4)
00000000000ea55a: 5410d00c n %r1,12(%r13)
00000000000ea55e: 1211 ltr %r1,%r1
Call Trace:
([<0000000000000000>] 0x0)
[<000000000001fa22>] do_syscall_trace_exit+0x132/0x18c
[<000000000002d0c4>] sysc_return+0x0/0x8
[<000000000001c738>] kernel_thread_starter+0x0/0xc
Last Breaking-Event-Address:
[<00000000000ea51e>] ftrace_syscall_exit+0x2a/0xdc
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Jiaying Zhang <jiayingz@google.com>
Cc: Martin Bligh <mbligh@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
LKML-Reference: <20090825125027.GE4639@cetus.boeblingen.de.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
There are many clock sources for the tracing system but we can only
enable/disable one at a time with the trace/options file.
We can move the setting of clock-source out of options and add a separate
file for it:
# cat trace_clock
[local] global
# echo global > trace_clock
# cat trace_clock
local [global]
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
LKML-Reference: <4A939D08.6050604@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Usually, char * entries are dangerous in traces because the string
can be released whereas a pointer to it can still wait to be read from
the ring buffer.
But sometimes we can assume it's safe, like in case of RO data
(eg: __file__ or __line__, used in bkl trace event). If these RO data
are in a module and so is the call to the trace event, then it's safe,
because the ring buffer will be flushed once this module get unloaded.
To allow char * to be treated as a string:
TRACE_EVENT(...,
TP_STRUCT__entry(
__field_ext(const char *, name, FILTER_PTR_STRING)
...
)
...
);
The filtering will not dereference "char *" unless the developer
explicitly sets FILTER_PTR_STR in __field_ext.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4A7B9287.90205@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Add __field_ext(), so a field can be assigned to a specific
filter_type, which matches a corresponding filter function.
For example, a later patch will allow this:
__field_ext(const char *, str, FILTER_PTR_STR);
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4A7B9272.6050709@cn.fujitsu.com>
[
Fixed a -1 to FILTER_OTHER
Forward ported to latest kernel.
]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The type of a field is stored as a string in @type, and here
we add @filter_type which is an enum value.
This prepares for later patches, so we can specifically assign
different @filter_type for the same @type.
For example normally a "char *" field is treated as a ptr,
but we may want it to be treated as a string when doing filting.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4A7B925E.9030605@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The "format" file of a trace event is originally for parsers to
parse ftrace binary output.
But the "format" file of a syscall event can only be used by
perfcounter, because it describes the format of struct
syscall_enter_record not struct syscall_trace_enter.
To fix this, we remove struct syscall_enter_record, and then
struct syscall_trace_enter will be used by both perf profile
and ftrace.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A8BAF39.1030404@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
"echo noglobal-clock > trace_options" can be used to change trace
clock but "echo 0 > options/global-clock" can't. The flag toggling
will be silently accepted without actually changing the clock callback.
We can fix it by using set_tracer_flags() in
trace_options_core_write().
Changelog:
v1->v2: Simplified switch() after Li Zefan <lizf@cn.fujitsu.com>'s
suggestion
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
One entry is missing in the output of a stat file.
The cause is, when stat_seq_start() is called the 2nd time, we
should start from the (pos-1)th elem in the rbtree but not pos,
because pos == 0 is the header.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A891A65.70009@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When syscall tracing was implemented as a tracer,
"syscall_arg_type" trace option could be set to enable the
display of syscall parameter types.
Now this option is gone since it's no longer a tracer, but the
code is still there but dead.
So we remove dead code and re-enable the printing of paramete
types via the verbose option:
# echo verbose > trace_options
# echo syscalls > set_event
# cat trace
...
bash-3331 [000] 95.348937: sys_fcntl64 -> 0x1
bash-3331 [000] 95.348942: sys_close(unsigned int fd: a)
...
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jason Baron <jbaron@redhat.com>
LKML-Reference: <4A891AF6.5050102@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Conflicts:
arch/sparc/kernel/smp_64.c
arch/x86/kernel/cpu/perf_counter.c
arch/x86/kernel/setup_percpu.c
drivers/cpufreq/cpufreq_ondemand.c
mm/percpu.c
Conflicts in core and arch percpu codes are mostly from commit
ed78e1e078dd44249f88b1dd8c76dafb39567161 which substituted many
num_possible_cpus() with nr_cpu_ids. As for-next branch has moved all
the first chunk allocators into mm/percpu.c, the changes are moved
from arch code to mm/percpu.c.
Signed-off-by: Tejun Heo <tj@kernel.org>
commit fd51d251e4
Author: Stefan Raspl <raspl@linux.vnet.ibm.com>
Date: Tue May 19 09:59:08 2009 +0200
blktrace: remove debugfs entries on bad path
added in an explicit invocation of debugfs_remove for bt->dir, in
blk_remove_buf_file_callback we are also getting the directory removed. On
occasion I am seeing memory corruption that I have bisected down to
this commit. [The testing involves a (long) series of I/O benchmarks
with blktrace invoked around the actual runs.] I believe that this
committed patch is correct, but the problem actually lies in the code
in blk_remove_buf_file_callback.
With this patch I am able to consistently get complete runs whereas
previously I could not get a single run to complete.
The first part of the patch simply moves the debugfs_remove below the
relay_close: the relay_close call will remove files under bt->dir, and
so we should not remove the directory until all the files we created
have been removed. (Note: This is not sufficient to fix the problem -
the file system code has ref counts on the directoy, so our invocation
does not cause the directory to actually be removed. Nonetheless, we
should not rely upon that feature.)
Signed-off-by: Alan D. Brunelle <alan.brunelle@hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Define the format of the syscall trace fields to parse the binary
values from a raw trace using the syscall events "format" file.
This is defined dynamically using the syscalls metadata.
It prepares the export of syscall event raw records to perf
counters.
Example:
$ cat /debug/tracing/events/syscalls/sys_enter_sched_getparam/format
name: sys_enter_sched_getparam
ID: 39
format:
field:unsigned short common_type; offset:0; size:2;
field:unsigned char common_flags; offset:2; size:1;
field:unsigned char common_preempt_count; offset:3; size:1;
field:int common_pid; offset:4; size:4;
field:int common_tgid; offset:8; size:4;
field:pid_t pid; offset:12; size:8;
field:struct sched_param * param; offset:20; size:8;
print fmt: "pid: 0x%08lx, param: 0x%08lx", ((unsigned long)(REC->pid)), ((unsigned long)(REC->param))
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Jiaying Zhang <jiayingz@google.com>
Cc: Martin Bligh <mbligh@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jason Baron <jbaron@redhat.com>
