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* ftrace: return error on failed modified text.Steven Rostedt2008-10-231-6/+15
| | | | | | | | | | | | | Have the ftrace_modify_code return error values: -EFAULT on error of reading the address -EINVAL if what is read does not match what it expected -EPERM if the write fails to update after a successful match. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: release functions from hashSteven Rostedt2008-10-201-0/+43
| | | | | | | | | | | | | | | | | | | | | The x86 architecture uses a static recording of mcount caller locations and is not affected by this patch. For architectures still using the dynamic ftrace daemon, this patch is critical. It removes the race between the recording of a function that calls mcount, the unloading of a module, and the ftrace daemon updating the call sites. This patch adds the releasing of the hash functions that the daemon uses to update the mcount call sites. When a module is unloaded, not only are the replaced call site table update, but now so is the hash recorded functions that the ftrace daemon will use. Again, architectures that implement MCOUNT_RECORD are not affected by this (which currently only x86 has). Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: warn on failure to disable mcount callersSteven Rostedt2008-10-141-0/+27
| | | | | | | | | | | | With the recent updates to ftrace, there should not be any failures when modifying the code. If there is, then we need to warn about it. This patch has a cleaned up version of the code that I used to discover that the weak symbols were causing failures. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: mcount_addr defined but not usedSteven Noonan2008-10-141-8/+8
| | | | | | | | When CONFIG_DYNAMIC_FTRACE isn't used, neither is mcount_addr. This patch eliminates that warning. Signed-off-by: Steven Noonan <steven@uplinklabs.net> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: fix unlocking of hashSteven Rostedt2008-10-141-1/+2
| | | | | | | | | | | | | | | | This must be brown paper bag week for Steven Rostedt! While working on ftrace for PPC, I discovered that the hash locking done when CONFIG_FTRACE_MCOUNT_RECORD is not set, is totally incorrect. With a cut and paste error, I had the hash lock macro to lock for both hash_lock _and_ hash_unlock! This bug did not affect x86 since this bug was introduced when CONFIG_FTRACE_MCOUNT_RECORD was added to x86. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: remove direct reference to mcount in trace codeSteven Rostedt2008-10-141-1/+9
| | | | | | | | | | | | | | The mcount record method of ftrace scans objdump for references to mcount. Using mcount as the reference to test if the calls to mcount being replaced are indeed calls to mcount, this use of mcount was also caught as a location to change. Using a variable that points to the mcount address moves this reference into the data section that is not scanned, and we do not use a false location to try and modify. The warn on code was what was used to detect this bug. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: clean up macro usageIngo Molnar2008-10-141-1/+1
| | | | | | | enclose the argument in parenthesis. (especially since we cast it, which is a high prio operation) Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: fix build failureStephen Rothwell2008-10-141-2/+2
| | | | | | | | | | | | | | | After disabling FTRACE_MCOUNT_RECORD via a patch, a dormant build failure surfaced: kernel/trace/ftrace.c: In function 'ftrace_record_ip': kernel/trace/ftrace.c:416: error: incompatible type for argument 1 of '_spin_lock_irqsave' kernel/trace/ftrace.c:433: error: incompatible type for argument 1 of '_spin_lock_irqsave' Introduced by commit 6dad8e07f4c10b17b038e84d29f3ca41c2e55cd0 ("ftrace: add necessary locking for ftrace records"). Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: add necessary locking for ftrace recordsSteven Rostedt2008-10-141-14/+30
| | | | | | | | | | | | | | | The new design of pre-recorded mcounts and updating the code outside of kstop_machine has changed the way the records themselves are protected. This patch uses the ftrace_lock to protect the records. Note, the lock still does not need to be taken within calls that are only called via kstop_machine, since the that code can not run while the spin lock is held. Also removed the hash_lock needed for the daemon when MCOUNT_RECORD is configured. Also did a slight cleanup of an unused variable. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: do not init module on ftrace disabledSteven Rostedt2008-10-141-2/+2
| | | | | | | | If one of the self tests of ftrace has disabled the function tracer, do not run the code to convert the mcount calls in modules. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: remove old pointers to mcountSteven Rostedt2008-10-141-2/+30
| | | | | | | | | | | | | | | | | | | | When a mcount pointer is recorded into a table, it is used to add or remove calls to mcount (replacing them with nops). If the code is removed via removing a module, the pointers still exist. At modifying the code a check is always made to make sure the code being replaced is the code expected. In-other-words, the code being replaced is compared to what it is expected to be before being replaced. There is a very small chance that the code being replaced just happens to look like code that calls mcount (very small since the call to mcount is relative). To remove this chance, this patch adds ftrace_release to allow module unloading to remove the pointers to mcount within the module. Another change for init calls is made to not trace calls marked with __init. The tracing can not be started until after init is done anyway. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: do not show freed records in available_filter_functionsSteven Rostedt2008-10-141-6/+4
| | | | | | | | Seems that freed records can appear in the available_filter_functions list. This patch fixes that. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: enable mcount recording for modulesSteven Rostedt2008-10-141-0/+5
| | | | | | | | | | | This patch enables the loading of the __mcount_section of modules and changing all the callers of mcount into nops. The modification is done before the init_module function is called, so again, we do not need to use kstop_machine to make these changes. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: mcount call site on boot nops coreSteven Rostedt2008-10-141-43/+105
| | | | | | | | | | | | | | | | | This is the infrastructure to the converting the mcount call sites recorded by the __mcount_loc section into nops on boot. It also allows for using these sites to enable tracing as normal. When the __mcount_loc section is used, the "ftraced" kernel thread is disabled. This uses the current infrastructure to record the mcount call sites as well as convert them to nops. The mcount function is kept as a stub on boot up and not converted to the ftrace_record_ip function. We use the ftrace_record_ip to only record from the table. This patch does not handle modules. That comes with a later patch. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* stop_machine: fix up ftrace.cRusty Russell2008-07-281-3/+3
| | | | | | | | | Simple conversion. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Abhishek Sagar <sagar.abhishek@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Steven Rostedt <rostedt@goodmis.org>
* ftrace: build fix for ftraced_suspendIngo Molnar2008-07-111-0/+2
| | | | | | | | | | fix: kernel/trace/ftrace.c:1615: error: 'ftraced_suspend' undeclared (first use in this function) kernel/trace/ftrace.c:1615: error: (Each undeclared identifier is reported only once kernel/trace/ftrace.c:1615: error: for each function it appears in.) Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: add ftrace_kill_atomicSteven Rostedt2008-07-111-0/+15
| | | | | | | | | | | | | It has been suggested that I add a way to disable the function tracer on an oops. This code adds a ftrace_kill_atomic. It is not meant to be used in normal situations. It will disable the ftrace tracer, but will not perform the nice shutdown that requires scheduling. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Cc: Steven Rostedt <srostedt@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: prevent ftrace modifications while being kprobe'd, v2Abhishek Sagar2008-07-031-1/+8
| | | | | | | | add two missing chunks for ftrace+kprobe. Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: avoid modifying kprobe'd recordsAbhishek Sagar2008-06-231-4/+31
| | | | | | | | | | | Avoid modifying the mcount call-site if there is a kprobe installed on it. These records are not marked as failed however. This allowed the filter rules on them to remain up-to-date. Whenever the kprobe on the corresponding record is removed, the record gets updated as normal. Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: freeze kprobe'd recordsAbhishek Sagar2008-06-231-1/+71
| | | | | | | | | | | | | | Let records identified as being kprobe'd be marked as "frozen". The trouble with records which have a kprobe installed on their mcount call-site is that they don't get updated. So if such a function which is currently being traced gets its tracing disabled due to a new filter rule (or because it was added to the notrace list) then it won't be updated and continue being traced. This patch allows scanning of all frozen records during tracing to check if they should be traced. Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: store mcount address in rec->ipAbhishek Sagar2008-06-231-1/+2
| | | | | | | | | | | | Record the address of the mcount call-site. Currently all archs except sparc64 record the address of the instruction following the mcount call-site. Some general cleanups are entailed. Storing mcount addresses in rec->ip enables looking them up in the kprobe hash table later on to check if they're kprobe'd. Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com> Cc: davem@davemloft.net Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* namespacecheck: fixesIngo Molnar2008-06-161-1/+1
| | | | Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: fix "notrace" filtering priorityAbhishek Sagar2008-06-141-3/+9
| | | | | | | | | | | | | This is a fix to give notrace filter rules priority over "set_ftrace_filter" rules. This fix ensures that functions which are set to be filtered and are concurrently marked as "notrace" don't get recorded. As of now, if a record is marked as FTRACE_FL_FILTER and is enabled, then the notrace flag is not checked. Tested on x86-32. Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: prevent freeing of all failed updatesAbhishek Sagar2008-06-101-3/+2
| | | | | | | | | | Steven Rostedt wrote: > If we unload a module and reload it, will it ever get converted again? The intent was always to filter core kernel functions to prevent their freeing. Here's a fix which should allow re-recording of module call-sites. Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: add debugfs entry 'failures'Abhishek Sagar2008-06-101-1/+39
| | | | | | | | | | Identify functions which had their mcount call-site updates failed. This can help us track functions which ftrace shouldn't fiddle with, and are thus not being traced. If there is no race with any external agent which is modifying the mcount call-site, then this file displays no entries (normal case). Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: remove ftrace_ip_converted()Abhishek Sagar2008-06-101-7/+0
| | | | | | | Remove the unneeded function ftrace_ip_converted(). Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: prevent freeing of all failed updatesAbhishek Sagar2008-06-101-30/+46
| | | | | | | | | | | | Prevent freeing of records which cause problems and correspond to function from core kernel text. A new flag, FTRACE_FL_CONVERTED is used to mark a record as "converted". All other records are patched lazily to NOPs. Failed records now also remain on frace_hash table. Each invocation of ftrace_record_ip now checks whether the traced function has ever been recorded (including past failures) and doesn't re-record it again. Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: user update and disable dynamic ftrace daemonSteven Rostedt2008-06-021-47/+110
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In dynamic ftrace, the mcount function starts off pointing to a stub function that just returns. On start up, the call to the stub is modified to point to a "record_ip" function. The job of the record_ip function is to add the function to a pre-allocated hash list. If the function is already there, it simply is ignored, otherwise it is added to the list. Later, a ftraced daemon wakes up and calls kstop_machine if any functions have been recorded, and changes the calls to the recorded functions to a simple nop. If no functions were recorded, the daemon goes back to sleep. The daemon wakes up once a second to see if it needs to update any newly recorded functions into nops. Usually it does not, but if a lot of code has been executed for the first time in the kernel, the ftraced daemon will call kstop_machine to update those into nops. The problem currently is that there's no way to stop the daemon from doing this, and it can cause unneeded latencies (800us which for some is bothersome). This patch adds a new file /debugfs/tracing/ftraced_enabled. If the daemon is active, reading this will return "enabled\n" and "disabled\n" when the daemon is not running. To disable the daemon, the user can echo "0" or "disable" into this file, and "1" or "enable" to re-enable the daemon. Since the daemon is used to convert the functions into nops to increase the performance of the system, I also added that anytime something is written into the ftraced_enabled file, kstop_machine will run if there are new functions that have been detected that need to be converted. This way the user can disable the daemon but still be able to control the conversion of the mcount calls to nops by simply, "echo 0 > /debugfs/tracing/ftraced_enabled" when they need to do more conversions. To see the number of converted functions: "cat /debugfs/tracing/dyn_ftrace_total_info" Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: fix updating of ftrace_update_cntAbhishek Sagar2008-05-261-3/+5
| | | | | | | | | | | | Hi Ingo/Steven, Ftrace currently maintains an update count which includes false updates, i.e, updates which failed. If anything, such failures should be tracked by some separate variable, but this patch provides a minimal fix. Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com> Cc: rostedt@goodmis.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: safe traversal of ftrace_hash hlistAbhishek Sagar2008-05-261-2/+2
| | | | | | | | | | | | | Hi Steven, I noticed that concurrent instances of ftrace_record_ip() have a race between ftrace_hash list traversal during ftrace_ip_in_hash() (before acquiring ftrace_shutdown_lock) and ftrace_add_hash(). If it's so then this should fix it. Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com> Cc: rostedt@goodmis.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: set_ftrace_notrace featureSteven Rostedt2008-05-261-40/+130
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | While debugging latencies in the RT kernel, I found that it would be nice to be able to filter away functions from the trace than just to filter on functions. I added a new interface to the debugfs tracing directory called set_ftrace_notrace When dynamic frace is enabled, this lets you filter away functions that will not be recorded in the trace. It is similar to adding 'notrace' to those functions but by doing it without recompiling the kernel. Here's how set_ftrace_filter and set_ftrace_notrace interact. Remember, if set_ftrace_filter is set, it removes all functions from the trace execpt for those listed in the set_ftrace_filter. set_ftrace_notrace will prevent those functions from being traced. If you were to set one function in both set_ftrace_filter and set_ftrace_notrace and that function was the same, then you would end up with an empty trace. the set of functions to trace is: set_ftrace_filter == empty then all functions not in set_ftrace_notrace else set of the set_ftrace_filter and not in set of set_ftrace_notrace. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: cleanupsIngo Molnar2008-05-231-3/+3
| | | | | | | factor out code and clean it up. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: fix mcount export bugIngo Molnar2008-05-231-3/+0
| | | | | | | | | | David S. Miller noticed the following bug: the -pg instrumentation function callback is named differently on each platform. On x86 it is mcount, on sparc it is _mcount. So the export does not make sense in kernel/trace/ftrace.c - move it to x86. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: remove packed attribute on ftrace_page.David Miller2008-05-231-2/+2
| | | | | | | | | | | | | | | | It causes unaligned access traps on platforms like sparc (ftrace_page may be marked packed, but once we return a dyn_ftrace sub-object from this array to another piece of code, the "packed" part of the typing information doesn't propagate). But also, it didn't serve any purpose either. Even if packed, on 64-bit or 32-bit, it didn't give us any more dyn_ftrace entries per-page. Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: use raw_smp_processor_id for mcount functionsSteven Rostedt2008-05-231-4/+11
| | | | | | | | | | | | | | Due to debug hooks in the kernel that can change the way smp_processor_id works, use raw_smp_processor_id in mcount called functions (namely ftrace_record_ip). Currently we annotate most debug functions from calling mcount, but we should not rely on that to prevent kernel lockups. This patch uses the raw_smp_processor_id to prevent a recusive crash that can happen if a debug hook in smp_processor_id calls mcount. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: add UNINTERRUPTIBLE state for kftraced on disableSteven Rostedt2008-05-231-4/+2
| | | | | | | | | | | | When dynamic ftrace fails and sets itself disabled, the ftraced daemon will go back to sleep everytime it wakes up. The setting of the ftraced state to UNINTERRUPTIBLE is skipped in this process, and the daemon takes up 100% of the CPU. This patch makes sure the ftraced daemon sets itself to UNINTERRUPTIBLE in that loop. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: remove notraceIngo Molnar2008-05-231-33/+33
| | | | | | | | now that we have a kbuild method for notrace, no need to pollute the C code with the annotations. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: remove address of function namesSteven Rostedt2008-05-231-2/+2
| | | | | | | | | | | | | PowerPC is very fragile when it comes to use of function names and function addresses. ftrace needs to either use all function addresses or function names (i.e. my_func as suppose to &my_func). This patch chooses to use the names and not the addresses, and makes ftrace consistent. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: cleanupsIngo Molnar2008-05-231-2/+3
| | | | | | | clean up recent code. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: disable tracing on failureSteven Rostedt2008-05-231-9/+103
| | | | | | | | | | | | | | Since ftrace touches practically every function. If we detect any anomaly, we want to fully disable ftrace. This patch adds code to try shutdown ftrace as much as possible without doing any more harm is something is detected not quite correct. This only kills ftrace, this patch does have checks for other parts of the tracer (irqsoff, wakeup, etc.). Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace - fix dynamic ftrace memory leakSteven Rostedt2008-05-231-3/+42
| | | | | | | | | | | | | | | | | | | | The ftrace dynamic function update allocates a record to store the instruction pointers that are being modified. If the modified instruction pointer fails to update, then the record is marked as failed and nothing more is done. Worse, if the modification fails, but the record ip function is still called, it will allocate a new record and try again. In just a matter of time, will this cause a serious memory leak and crash the system. This patch plugs this memory leak. When a record fails, it is included back into the pool of records to be used. Now a record may fail over and over again, but the number of allocated records will not increase. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: timestamp syncing, prepareIngo Molnar2008-05-231-2/+2
| | | | | | | rename and uninline now() to ftrace_now(). Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: cleanupsIngo Molnar2008-05-231-1/+4
| | | | | | | no code changed. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: startup tester on dynamic tracing.Steven Rostedt2008-05-231-0/+19
| | | | | | | | | | | | | | This patch adds a startup self test on dynamic code modification and filters. The test filters on a specific function, makes sure that no other function is traced, exectutes the function, then makes sure that the function is traced. This patch also fixes a slight bug with the ftrace selftest, where tracer_enabled was not being set. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: cleanupsIngo Molnar2008-05-231-4/+4
| | | | | | | factor out code and clean it up. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: force recordingSteven Rostedt2008-05-231-0/+51
| | | | | Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: add filter select functions to traceSteven Rostedt2008-05-231-17/+510
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds two files to the debugfs system: /debugfs/tracing/available_filter_functions and /debugfs/tracing/set_ftrace_filter The available_filter_functions lists all functions that has been recorded by the ftraced that has called the ftrace_record_ip function. This is to allow users to see what functions have been converted to nops and can be enabled for tracing. To enable functions, simply echo the names (whitespace delimited) into set_ftrace_filter. Simple wildcards are also allowed. echo 'scheduler' > /debugfs/tracing/set_ftrace_filter Will have only the scheduler be activated when tracing is enabled. echo 'sched_*' > /debugfs/tracing/set_ftrace_filter Will have only the functions starting with 'sched_' be activated. echo '*lock' > /debugfs/tracing/set_ftrace_filter Will have only functions ending with 'lock' be activated. echo '*lock*' > /debugfs/tracing/set_ftrace_filter Will have only functions with 'lock' in its name be activated. Note: 'sched*lock' will not work. The only wildcards that are allowed is an asterisk and the beginning and or end of the string passed in. Multiple names can be passed in with whitespace delimited: echo 'scheduler *lock *acpi*' > /debugfs/tracing/set_ftrace_filter is also the same as: echo 'scheduler' > /debugfs/tracing/set_ftrace_filter echo '*lock' >> /debugfs/tracing/set_ftrace_filter echo '*acpi*' >> /debugfs/tracing/set_ftrace_filter Appending does just that. It appends to the list. To disable all filters simply echo an empty line in: echo > /debugfs/tracing/set_ftrace_filter Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: use dynamic patching for updating mcount callsSteven Rostedt2008-05-231-78/+105
| | | | | | | | | | | | | | | | | | | | | | | | | | | This patch replaces the indirect call to the mcount function pointer with a direct call that will be patched by the dynamic ftrace routines. On boot up, the mcount function calls the ftace_stub function. When the dynamic ftrace code is initialized, the ftrace_stub is replaced with a call to the ftrace_record_ip, which records the instruction pointers of the locations that call it. Later, the ftraced daemon will call kstop_machine and patch all the locations to nops. When a ftrace is enabled, the original calls to mcount will now be set top call ftrace_caller, which will do a direct call to the registered ftrace function. This direct call is also patched when the function that should be called is updated. All patching is performed by a kstop_machine routine to prevent any type of race conditions that is associated with modifying code on the fly. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: move memory management out of arch codeSteven Rostedt2008-05-231-2/+152
| | | | | | | | | | This patch moves the memory management of the ftrace records out of the arch code and into the generic code making the arch code simpler. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* ftrace: add ftrace_enabled sysctl to disable mcount functionSteven Rostedt2008-05-231-18/+107
| | | | | | | | | | | | | | | This patch adds back the sysctl ftrace_enabled. This time it is defaulted to on, if DYNAMIC_FTRACE is configured. When ftrace_enabled is disabled, the ftrace function is set to the stub return. If DYNAMIC_FTRACE is also configured, on ftrace_enabled = 0, the registered ftrace functions will all be set to jmps, but no more new calls to ftrace recording (used to find the ftrace calling sites) will be called. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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