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* fgraph: Initialize tracing_graph_pause at task creationSteven Rostedt (VMware)2021-02-23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 7e0a9220467dbcfdc5bc62825724f3e52e50ab31 upstream. On some archs, the idle task can call into cpu_suspend(). The cpu_suspend() will disable or pause function graph tracing, as there's some paths in bringing down the CPU that can have issues with its return address being modified. The task_struct structure has a "tracing_graph_pause" atomic counter, that when set to something other than zero, the function graph tracer will not modify the return address. The problem is that the tracing_graph_pause counter is initialized when the function graph tracer is enabled. This can corrupt the counter for the idle task if it is suspended in these architectures. CPU 1 CPU 2 ----- ----- do_idle() cpu_suspend() pause_graph_tracing() task_struct->tracing_graph_pause++ (0 -> 1) start_graph_tracing() for_each_online_cpu(cpu) { ftrace_graph_init_idle_task(cpu) task-struct->tracing_graph_pause = 0 (1 -> 0) unpause_graph_tracing() task_struct->tracing_graph_pause-- (0 -> -1) The above should have gone from 1 to zero, and enabled function graph tracing again. But instead, it is set to -1, which keeps it disabled. There's no reason that the field tracing_graph_pause on the task_struct can not be initialized at boot up. Cc: stable@vger.kernel.org Fixes: 380c4b1411ccd ("tracing/function-graph-tracer: append the tracing_graph_flag") Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=211339 Reported-by: pierre.gondois@arm.com Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tracing: Do not count ftrace events in top level enable outputSteven Rostedt (VMware)2021-02-23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 256cfdd6fdf70c6fcf0f7c8ddb0ebd73ce8f3bc9 upstream. The file /sys/kernel/tracing/events/enable is used to enable all events by echoing in "1", or disabling all events when echoing in "0". To know if all events are enabled, disabled, or some are enabled but not all of them, cating the file should show either "1" (all enabled), "0" (all disabled), or "X" (some enabled but not all of them). This works the same as the "enable" files in the individule system directories (like tracing/events/sched/enable). But when all events are enabled, the top level "enable" file shows "X". The reason is that its checking the "ftrace" events, which are special events that only exist for their format files. These include the format for the function tracer events, that are enabled when the function tracer is enabled, but not by the "enable" file. The check includes these events, which will always be disabled, and even though all true events are enabled, the top level "enable" file will show "X" instead of "1". To fix this, have the check test the event's flags to see if it has the "IGNORE_ENABLE" flag set, and if so, not test it. Cc: stable@vger.kernel.org Fixes: 553552ce1796c ("tracing: Combine event filter_active and enable into single flags field") Reported-by: "Yordan Karadzhov (VMware)" <y.karadz@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tracing: Fix race in trace_open and buffer resize callGaurav Kohli2021-01-30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit bbeb97464eefc65f506084fd9f18f21653e01137 upstream. Below race can come, if trace_open and resize of cpu buffer is running parallely on different cpus CPUX CPUY ring_buffer_resize atomic_read(&buffer->resize_disabled) tracing_open tracing_reset_online_cpus ring_buffer_reset_cpu rb_reset_cpu rb_update_pages remove/insert pages resetting pointer This race can cause data abort or some times infinte loop in rb_remove_pages and rb_insert_pages while checking pages for sanity. Take buffer lock to fix this. Link: https://lkml.kernel.org/r/1601976833-24377-1-git-send-email-gkohli@codeaurora.org Cc: stable@vger.kernel.org Fixes: 83f40318dab00 ("ring-buffer: Make removal of ring buffer pages atomic") Reported-by: Denis Efremov <efremov@linux.com> Signed-off-by: Gaurav Kohli <gkohli@codeaurora.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tracing: Fix userstacktrace option for instancesSteven Rostedt (VMware)2020-12-11
| | | | | | | | | | | | | | | commit bcee5278958802b40ee8b26679155a6d9231783e upstream. When the instances were able to use their own options, the userstacktrace option was left hardcoded for the top level. This made the instance userstacktrace option bascially into a nop, and will confuse users that set it, but nothing happens (I was confused when it happened to me!) Cc: stable@vger.kernel.org Fixes: 16270145ce6b ("tracing: Add trace options for core options to instances") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* ring-buffer: Fix recursion protection transitions between interrupt contextSteven Rostedt (VMware)2020-11-18
| | | | | | | | | | | | | | | | | | [ Upstream commit b02414c8f045ab3b9afc816c3735bc98c5c3d262 ] The recursion protection of the ring buffer depends on preempt_count() to be correct. But it is possible that the ring buffer gets called after an interrupt comes in but before it updates the preempt_count(). This will trigger a false positive in the recursion code. Use the same trick from the ftrace function callback recursion code which uses a "transition" bit that gets set, to allow for a single recursion for to handle transitions between contexts. Cc: stable@vger.kernel.org Fixes: 567cd4da54ff4 ("ring-buffer: User context bit recursion checking") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
* ftrace: Handle tracing when switching between contextSteven Rostedt (VMware)2020-11-10
| | | | | | | | | | | | | | | | | | | | | | | | | | commit 726b3d3f141fba6f841d715fc4d8a4a84f02c02a upstream. When an interrupt or NMI comes in and switches the context, there's a delay from when the preempt_count() shows the update. As the preempt_count() is used to detect recursion having each context have its own bit get set when tracing starts, and if that bit is already set, it is considered a recursion and the function exits. But if this happens in that section where context has changed but preempt_count() has not been updated, this will be incorrectly flagged as a recursion. To handle this case, create another bit call TRANSITION and test it if the current context bit is already set. Flag the call as a recursion if the TRANSITION bit is already set, and if not, set it and continue. The TRANSITION bit will be cleared normally on the return of the function that set it, or if the current context bit is clear, set it and clear the TRANSITION bit to allow for another transition between the current context and an even higher one. Cc: stable@vger.kernel.org Fixes: edc15cafcbfa3 ("tracing: Avoid unnecessary multiple recursion checks") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* ftrace: Fix recursion check for NMI testSteven Rostedt (VMware)2020-11-10
| | | | | | | | | | | | | | | | | | | | | | commit ee11b93f95eabdf8198edd4668bf9102e7248270 upstream. The code that checks recursion will work to only do the recursion check once if there's nested checks. The top one will do the check, the other nested checks will see recursion was already checked and return zero for its "bit". On the return side, nothing will be done if the "bit" is zero. The problem is that zero is returned for the "good" bit when in NMI context. This will set the bit for NMIs making it look like *all* NMI tracing is recursing, and prevent tracing of anything in NMI context! The simple fix is to return "bit + 1" and subtract that bit on the end to get the real bit. Cc: stable@vger.kernel.org Fixes: edc15cafcbfa3 ("tracing: Avoid unnecessary multiple recursion checks") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* ring-buffer: Return 0 on success from ring_buffer_resize()Qiujun Huang2020-11-10
| | | | | | | | | | | | | | | | | | | | | | | commit 0a1754b2a97efa644aa6e84d1db5b17c42251483 upstream. We don't need to check the new buffer size, and the return value had confused resize_buffer_duplicate_size(). ... ret = ring_buffer_resize(trace_buf->buffer, per_cpu_ptr(size_buf->data,cpu_id)->entries, cpu_id); if (ret == 0) per_cpu_ptr(trace_buf->data, cpu_id)->entries = per_cpu_ptr(size_buf->data, cpu_id)->entries; ... Link: https://lkml.kernel.org/r/20201019142242.11560-1-hqjagain@gmail.com Cc: stable@vger.kernel.org Fixes: d60da506cbeb3 ("tracing: Add a resize function to make one buffer equivalent to another buffer") Signed-off-by: Qiujun Huang <hqjagain@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tracing: Use address-of operator on section symbolsNathan Chancellor2020-10-01
| | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit bf2cbe044da275021b2de5917240411a19e5c50d ] Clang warns: ../kernel/trace/trace.c:9335:33: warning: array comparison always evaluates to true [-Wtautological-compare] if (__stop___trace_bprintk_fmt != __start___trace_bprintk_fmt) ^ 1 warning generated. These are not true arrays, they are linker defined symbols, which are just addresses. Using the address of operator silences the warning and does not change the runtime result of the check (tested with some print statements compiled in with clang + ld.lld and gcc + ld.bfd in QEMU). Link: http://lkml.kernel.org/r/20200220051011.26113-1-natechancellor@gmail.com Link: https://github.com/ClangBuiltLinux/linux/issues/893 Suggested-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
* tracing: Set kernel_stack's caller size properlyJosef Bacik2020-10-01
| | | | | | | | | | | | | | | | | | | [ Upstream commit cbc3b92ce037f5e7536f6db157d185cd8b8f615c ] I noticed when trying to use the trace-cmd python interface that reading the raw buffer wasn't working for kernel_stack events. This is because it uses a stubbed version of __dynamic_array that doesn't do the __data_loc trick and encode the length of the array into the field. Instead it just shows up as a size of 0. So change this to __array and set the len to FTRACE_STACK_ENTRIES since this is what we actually do in practice and matches how user_stack_trace works. Link: http://lkml.kernel.org/r/1411589652-1318-1-git-send-email-jbacik@fb.com Signed-off-by: Josef Bacik <jbacik@fb.com> [ Pulled from the archeological digging of my INBOX ] Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
* tracing: Adding NULL checks for trace_array descriptor pointerDivya Indi2020-10-01
| | | | | | | | | | | | | | [ Upstream commit 953ae45a0c25e09428d4a03d7654f97ab8a36647 ] As part of commit f45d1225adb0 ("tracing: Kernel access to Ftrace instances") we exported certain functions. Here, we are adding some additional NULL checks to ensure safe usage by users of these APIs. Link: http://lkml.kernel.org/r/1565805327-579-4-git-send-email-divya.indi@oracle.com Signed-off-by: Divya Indi <divya.indi@oracle.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
* ftrace: Setup correct FTRACE_FL_REGS flags for moduleChengming Zhou2020-10-01
| | | | | | | | | | | | | | | | | | | | | | [ Upstream commit 8a224ffb3f52b0027f6b7279854c71a31c48fc97 ] When module loaded and enabled, we will use __ftrace_replace_code for module if any ftrace_ops referenced it found. But we will get wrong ftrace_addr for module rec in ftrace_get_addr_new, because rec->flags has not been setup correctly. It can cause the callback function of a ftrace_ops has FTRACE_OPS_FL_SAVE_REGS to be called with pt_regs set to NULL. So setup correct FTRACE_FL_REGS flags for rec when we call referenced_filters to find ftrace_ops references it. Link: https://lkml.kernel.org/r/20200728180554.65203-1-zhouchengming@bytedance.com Cc: stable@vger.kernel.org Fixes: 8c4f3c3fa9681 ("ftrace: Check module functions being traced on reload") Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com> Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
* tracing: Fix event trigger to accept redundant spacesMasami Hiramatsu2020-06-29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 6784beada631800f2c5afd567e5628c843362cee upstream. Fix the event trigger to accept redundant spaces in the trigger input. For example, these return -EINVAL echo " traceon" > events/ftrace/print/trigger echo "traceon if common_pid == 0" > events/ftrace/print/trigger echo "disable_event:kmem:kmalloc " > events/ftrace/print/trigger But these are hard to find what is wrong. To fix this issue, use skip_spaces() to remove spaces in front of actual tokens, and set NULL if there is no token. Link: http://lkml.kernel.org/r/159262476352.185015.5261566783045364186.stgit@devnote2 Cc: Tom Zanussi <zanussi@kernel.org> Cc: stable@vger.kernel.org Fixes: 85f2b08268c0 ("tracing: Add basic event trigger framework") Reviewed-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* blktrace: break out of blktrace setup on concurrent callsLuis Chamberlain2020-06-29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit 1b0b283648163dae2a214ca28ed5a99f62a77319 ] We use one blktrace per request_queue, that means one per the entire disk. So we cannot run one blktrace on say /dev/vda and then /dev/vda1, or just two calls on /dev/vda. We check for concurrent setup only at the very end of the blktrace setup though. If we try to run two concurrent blktraces on the same block device the second one will fail, and the first one seems to go on. However when one tries to kill the first one one will see things like this: The kernel will show these: ``` debugfs: File 'dropped' in directory 'nvme1n1' already present! debugfs: File 'msg' in directory 'nvme1n1' already present! debugfs: File 'trace0' in directory 'nvme1n1' already present! `` And userspace just sees this error message for the second call: ``` blktrace /dev/nvme1n1 BLKTRACESETUP(2) /dev/nvme1n1 failed: 5/Input/output error ``` The first userspace process #1 will also claim that the files were taken underneath their nose as well. The files are taken away form the first process given that when the second blktrace fails, it will follow up with a BLKTRACESTOP and BLKTRACETEARDOWN. This means that even if go-happy process #1 is waiting for blktrace data, we *have* been asked to take teardown the blktrace. This can easily be reproduced with break-blktrace [0] run_0005.sh test. Just break out early if we know we're already going to fail, this will prevent trying to create the files all over again, which we know still exist. [0] https://github.com/mcgrof/break-blktrace Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org>
* Stop the ad-hoc games with -Wno-maybe-initializedLinus Torvalds2020-05-20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 78a5255ffb6a1af189a83e493d916ba1c54d8c75 upstream. We have some rather random rules about when we accept the "maybe-initialized" warnings, and when we don't. For example, we consider it unreliable for gcc versions < 4.9, but also if -O3 is enabled, or if optimizing for size. And then various kernel config options disabled it, because they know that they trigger that warning by confusing gcc sufficiently (ie PROFILE_ALL_BRANCHES). And now gcc-10 seems to be introducing a lot of those warnings too, so it falls under the same heading as 4.9 did. At the same time, we have a very straightforward way to _enable_ that warning when wanted: use "W=2" to enable more warnings. So stop playing these ad-hoc games, and just disable that warning by default, with the known and straight-forward "if you want to work on the extra compiler warnings, use W=123". Would it be great to have code that is always so obvious that it never confuses the compiler whether a variable is used initialized or not? Yes, it would. In a perfect world, the compilers would be smarter, and our source code would be simpler. That's currently not the world we live in, though. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* kbuild: compute false-positive -Wmaybe-uninitialized cases in KconfigMasahiro Yamada2020-05-20
| | | | | | | | | | | | | | | | | | | | | | | | | | | commit b303c6df80c9f8f13785aa83a0471fca7e38b24d upstream. Since -Wmaybe-uninitialized was introduced by GCC 4.7, we have patched various false positives: - commit e74fc973b6e5 ("Turn off -Wmaybe-uninitialized when building with -Os") turned off this option for -Os. - commit 815eb71e7149 ("Kbuild: disable 'maybe-uninitialized' warning for CONFIG_PROFILE_ALL_BRANCHES") turned off this option for CONFIG_PROFILE_ALL_BRANCHES - commit a76bcf557ef4 ("Kbuild: enable -Wmaybe-uninitialized warning for "make W=1"") turned off this option for GCC < 4.9 Arnd provided more explanation in https://lkml.org/lkml/2017/3/14/903 I think this looks better by shifting the logic from Makefile to Kconfig. Link: https://github.com/ClangBuiltLinux/linux/issues/350 Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* blktrace: fix dereference after null checkCengiz Can2020-05-20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 153031a301bb07194e9c37466cfce8eacb977621 upstream. There was a recent change in blktrace.c that added a RCU protection to `q->blk_trace` in order to fix a use-after-free issue during access. However the change missed an edge case that can lead to dereferencing of `bt` pointer even when it's NULL: Coverity static analyzer marked this as a FORWARD_NULL issue with CID 1460458. ``` /kernel/trace/blktrace.c: 1904 in sysfs_blk_trace_attr_store() 1898 ret = 0; 1899 if (bt == NULL) 1900 ret = blk_trace_setup_queue(q, bdev); 1901 1902 if (ret == 0) { 1903 if (attr == &dev_attr_act_mask) >>> CID 1460458: Null pointer dereferences (FORWARD_NULL) >>> Dereferencing null pointer "bt". 1904 bt->act_mask = value; 1905 else if (attr == &dev_attr_pid) 1906 bt->pid = value; 1907 else if (attr == &dev_attr_start_lba) 1908 bt->start_lba = value; 1909 else if (attr == &dev_attr_end_lba) ``` Added a reassignment with RCU annotation to fix the issue. Fixes: c780e86dd48 ("blktrace: Protect q->blk_trace with RCU") Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Bob Liu <bob.liu@oracle.com> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Cengiz Can <cengiz@kernel.wtf> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* blktrace: Protect q->blk_trace with RCUJan Kara2020-05-20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit c780e86dd48ef6467a1146cf7d0fe1e05a635039 upstream. KASAN is reporting that __blk_add_trace() has a use-after-free issue when accessing q->blk_trace. Indeed the switching of block tracing (and thus eventual freeing of q->blk_trace) is completely unsynchronized with the currently running tracing and thus it can happen that the blk_trace structure is being freed just while __blk_add_trace() works on it. Protect accesses to q->blk_trace by RCU during tracing and make sure we wait for the end of RCU grace period when shutting down tracing. Luckily that is rare enough event that we can afford that. Note that postponing the freeing of blk_trace to an RCU callback should better be avoided as it could have unexpected user visible side-effects as debugfs files would be still existing for a short while block tracing has been shut down. Link: https://bugzilla.kernel.org/show_bug.cgi?id=205711 CC: stable@vger.kernel.org Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Tested-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reported-by: Tristan Madani <tristmd@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk> [bwh: Backported to 4.4: - Drop changes in blk_trace_note_message_enabled(), blk_trace_bio_get_cgid() - Adjust context] Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* blktrace: fix trace mutex deadlockJens Axboe2020-05-20
| | | | | | | | | | | | | | commit 2967acbb257a6a9bf912f4778b727e00972eac9b upstream. A previous commit changed the locking around registration/cleanup, but direct callers of blk_trace_remove() were missed. This means that if we hit the error path in setup, we will deadlock on attempting to re-acquire the queue trace mutex. Fixes: 1f2cac107c59 ("blktrace: fix unlocked access to init/start-stop/teardown") Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* blktrace: fix unlocked access to init/start-stop/teardownJens Axboe2020-05-20
| | | | | | | | | | | | | | | | commit 1f2cac107c591c24b60b115d6050adc213d10fc0 upstream. sg.c calls into the blktrace functions without holding the proper queue mutex for doing setup, start/stop, or teardown. Add internal unlocked variants, and export the ones that do the proper locking. Fixes: 6da127ad0918 ("blktrace: Add blktrace ioctls to SCSI generic devices") Tested-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* blktrace: Fix potential deadlock between delete & sysfs opsWaiman Long2020-05-20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 5acb3cc2c2e9d3020a4fee43763c6463767f1572 upstream. The lockdep code had reported the following unsafe locking scenario: CPU0 CPU1 ---- ---- lock(s_active#228); lock(&bdev->bd_mutex/1); lock(s_active#228); lock(&bdev->bd_mutex); *** DEADLOCK *** The deadlock may happen when one task (CPU1) is trying to delete a partition in a block device and another task (CPU0) is accessing tracing sysfs file (e.g. /sys/block/dm-1/trace/act_mask) in that partition. The s_active isn't an actual lock. It is a reference count (kn->count) on the sysfs (kernfs) file. Removal of a sysfs file, however, require a wait until all the references are gone. The reference count is treated like a rwsem using lockdep instrumentation code. The fact that a thread is in the sysfs callback method or in the ioctl call means there is a reference to the opended sysfs or device file. That should prevent the underlying block structure from being removed. Instead of using bd_mutex in the block_device structure, a new blk_trace_mutex is now added to the request_queue structure to protect access to the blk_trace structure. Suggested-by: Christoph Hellwig <hch@infradead.org> Signed-off-by: Waiman Long <longman@redhat.com> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Fix typo in patch subject line, and prune a comment detailing how the code used to work. Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* bpf, trace: check event type in bpf_perf_event_readAlexei Starovoitov2020-05-10
| | | | | | | | | | | | | | | commit ad572d174787daa59e24b8b5c83028c09cdb5ddb upstream. similar to bpf_perf_event_output() the bpf_perf_event_read() helper needs to check the type of the perf_event before reading the counter. Fixes: a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") Reported-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tracing: Fix the race between registering 'snapshot' event trigger and ↵Xiao Yang2020-04-24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | triggering 'snapshot' operation commit 0bbe7f719985efd9adb3454679ecef0984cb6800 upstream. Traced event can trigger 'snapshot' operation(i.e. calls snapshot_trigger() or snapshot_count_trigger()) when register_snapshot_trigger() has completed registration but doesn't allocate buffer for 'snapshot' event trigger. In the rare case, 'snapshot' operation always detects the lack of allocated buffer so make register_snapshot_trigger() allocate buffer first. trigger-snapshot.tc in kselftest reproduces the issue on slow vm: ----------------------------------------------------------- cat trace ... ftracetest-3028 [002] .... 236.784290: sched_process_fork: comm=ftracetest pid=3028 child_comm=ftracetest child_pid=3036 <...>-2875 [003] .... 240.460335: tracing_snapshot_instance_cond: *** SNAPSHOT NOT ALLOCATED *** <...>-2875 [003] .... 240.460338: tracing_snapshot_instance_cond: *** stopping trace here! *** ----------------------------------------------------------- Link: http://lkml.kernel.org/r/20200414015145.66236-1-yangx.jy@cn.fujitsu.com Cc: stable@vger.kernel.org Fixes: 93e31ffbf417a ("tracing: Add 'snapshot' event trigger command") Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* fs: prevent page refcount overflow in pipe_buf_getMatthew Wilcox2020-03-11
| | | | | | | | | | | | | | | | | | | | | | commit 15fab63e1e57be9fdb5eec1bbc5916e9825e9acb upstream. Change pipe_buf_get() to return a bool indicating whether it succeeded in raising the refcount of the page (if the thing in the pipe is a page). This removes another mechanism for overflowing the page refcount. All callers converted to handle a failure. Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Matthew Wilcox <willy@infradead.org> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [ 4.4.y backport notes: Regarding the change in generic_pipe_buf_get(), note that page_cache_get() is the same as get_page(). See mainline commit 09cbfeaf1a5a6 "mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros" for context. ] Signed-off-by: Ajay Kaher <akaher@vmware.com> Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* trigger_next should increase position indexVasily Averin2020-02-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit 6722b23e7a2ace078344064a9735fb73e554e9ef ] if seq_file .next fuction does not change position index, read after some lseek can generate unexpected output. Without patch: # dd bs=30 skip=1 if=/sys/kernel/tracing/events/sched/sched_switch/trigger dd: /sys/kernel/tracing/events/sched/sched_switch/trigger: cannot skip to specified offset n traceoff snapshot stacktrace enable_event disable_event enable_hist disable_hist hist # Available triggers: # traceon traceoff snapshot stacktrace enable_event disable_event enable_hist disable_hist hist 6+1 records in 6+1 records out 206 bytes copied, 0.00027916 s, 738 kB/s Notice the printing of "# Available triggers:..." after the line. With the patch: # dd bs=30 skip=1 if=/sys/kernel/tracing/events/sched/sched_switch/trigger dd: /sys/kernel/tracing/events/sched/sched_switch/trigger: cannot skip to specified offset n traceoff snapshot stacktrace enable_event disable_event enable_hist disable_hist hist 2+1 records in 2+1 records out 88 bytes copied, 0.000526867 s, 167 kB/s It only prints the end of the file, and does not restart. Link: http://lkml.kernel.org/r/3c35ee24-dd3a-8119-9c19-552ed253388a@virtuozzo.com https://bugzilla.kernel.org/show_bug.cgi?id=206283 Signed-off-by: Vasily Averin <vvs@virtuozzo.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
* tracing: Fix very unlikely race of registering two stat tracersSteven Rostedt (VMware)2020-02-28
| | | | | | | | | | | | | | | | | | | | | [ Upstream commit dfb6cd1e654315168e36d947471bd2a0ccd834ae ] Looking through old emails in my INBOX, I came across a patch from Luis Henriques that attempted to fix a race of two stat tracers registering the same stat trace (extremely unlikely, as this is done in the kernel, and probably doesn't even exist). The submitted patch wasn't quite right as it needed to deal with clean up a bit better (if two stat tracers were the same, it would have the same files). But to make the code cleaner, all we needed to do is to keep the all_stat_sessions_mutex held for most of the registering function. Link: http://lkml.kernel.org/r/1410299375-20068-1-git-send-email-luis.henriques@canonical.com Fixes: 002bb86d8d42f ("tracing/ftrace: separate events tracing and stats tracing engine") Reported-by: Luis Henriques <luis.henriques@canonical.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
* tracing: Have stack tracer compile when MCOUNT_INSN_SIZE is not definedSteven Rostedt (VMware)2020-01-14
| | | | | | | | | | | | | | | | | commit b8299d362d0837ae39e87e9019ebe6b736e0f035 upstream. On some archs with some configurations, MCOUNT_INSN_SIZE is not defined, and this makes the stack tracer fail to compile. Just define it to zero in this case. Link: https://lore.kernel.org/r/202001020219.zvE3vsty%lkp@intel.com Cc: stable@vger.kernel.org Fixes: 4df297129f622 ("tracing: Remove most or all of stack tracer stack size from stack_max_size") Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* kernel/trace: Fix do not unregister tracepoints when register ↵Kaitao Cheng2020-01-14
| | | | | | | | | | | | | | | | | | | sched_migrate_task fail commit 50f9ad607ea891a9308e67b81f774c71736d1098 upstream. In the function, if register_trace_sched_migrate_task() returns error, sched_switch/sched_wakeup_new/sched_wakeup won't unregister. That is why fail_deprobe_sched_switch was added. Link: http://lkml.kernel.org/r/20191231133530.2794-1-pilgrimtao@gmail.com Cc: stable@vger.kernel.org Fixes: 478142c39c8c2 ("tracing: do not grab lock in wakeup latency function tracing") Signed-off-by: Kaitao Cheng <pilgrimtao@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* ftrace: Avoid potential division by zero in function profilerWen Yang2020-01-12
| | | | | | | | | | | | | | | | | | | commit e31f7939c1c27faa5d0e3f14519eaf7c89e8a69d upstream. The ftrace_profile->counter is unsigned long and do_div truncates it to 32 bits, which means it can test non-zero and be truncated to zero for division. Fix this issue by using div64_ul() instead. Link: http://lkml.kernel.org/r/20200103030248.14516-1-wenyang@linux.alibaba.com Cc: stable@vger.kernel.org Fixes: e330b3bcd8319 ("tracing: Show sample std dev in function profiling") Fixes: 34886c8bc590f ("tracing: add average time in function to function profiler") Signed-off-by: Wen Yang <wenyang@linux.alibaba.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tracing: Initialize iter->seq after zeroing in tracing_read_pipe()Petr Mladek2019-11-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit d303de1fcf344ff7c15ed64c3f48a991c9958775 ] A customer reported the following softlockup: [899688.160002] NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [test.sh:16464] [899688.160002] CPU: 0 PID: 16464 Comm: test.sh Not tainted 4.12.14-6.23-azure #1 SLE12-SP4 [899688.160002] RIP: 0010:up_write+0x1a/0x30 [899688.160002] Kernel panic - not syncing: softlockup: hung tasks [899688.160002] RIP: 0010:up_write+0x1a/0x30 [899688.160002] RSP: 0018:ffffa86784d4fde8 EFLAGS: 00000257 ORIG_RAX: ffffffffffffff12 [899688.160002] RAX: ffffffff970fea00 RBX: 0000000000000001 RCX: 0000000000000000 [899688.160002] RDX: ffffffff00000001 RSI: 0000000000000080 RDI: ffffffff970fea00 [899688.160002] RBP: ffffffffffffffff R08: ffffffffffffffff R09: 0000000000000000 [899688.160002] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8b59014720d8 [899688.160002] R13: ffff8b59014720c0 R14: ffff8b5901471090 R15: ffff8b5901470000 [899688.160002] tracing_read_pipe+0x336/0x3c0 [899688.160002] __vfs_read+0x26/0x140 [899688.160002] vfs_read+0x87/0x130 [899688.160002] SyS_read+0x42/0x90 [899688.160002] do_syscall_64+0x74/0x160 It caught the process in the middle of trace_access_unlock(). There is no loop. So, it must be looping in the caller tracing_read_pipe() via the "waitagain" label. Crashdump analyze uncovered that iter->seq was completely zeroed at this point, including iter->seq.seq.size. It means that print_trace_line() was never able to print anything and there was no forward progress. The culprit seems to be in the code: /* reset all but tr, trace, and overruns */ memset(&iter->seq, 0, sizeof(struct trace_iterator) - offsetof(struct trace_iterator, seq)); It was added by the commit 53d0aa773053ab182877 ("ftrace: add logic to record overruns"). It was v2.6.27-rc1. It was the time when iter->seq looked like: struct trace_seq { unsigned char buffer[PAGE_SIZE]; unsigned int len; }; There was no "size" variable and zeroing was perfectly fine. The solution is to reinitialize the structure after or without zeroing. Link: http://lkml.kernel.org/r/20191011142134.11997-1-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
* tracing: Get trace_array reference for available_tracers filesSteven Rostedt (VMware)2019-10-17
| | | | | | | | | | | | | | | | commit 194c2c74f5532e62c218adeb8e2b683119503907 upstream. As instances may have different tracers available, we need to look at the trace_array descriptor that shows the list of the available tracers for the instance. But there's a race between opening the file and an admin deleting the instance. The trace_array_get() needs to be called before accessing the trace_array. Cc: stable@vger.kernel.org Fixes: 607e2ea167e56 ("tracing: Set up infrastructure to allow tracers for instances") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tracing/snapshot: Resize spare buffer if size changedEiichi Tsukata2019-08-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 46cc0b44428d0f0e81f11ea98217fc0edfbeab07 upstream. Current snapshot implementation swaps two ring_buffers even though their sizes are different from each other, that can cause an inconsistency between the contents of buffer_size_kb file and the current buffer size. For example: # cat buffer_size_kb 7 (expanded: 1408) # echo 1 > events/enable # grep bytes per_cpu/cpu0/stats bytes: 1441020 # echo 1 > snapshot // current:1408, spare:1408 # echo 123 > buffer_size_kb // current:123, spare:1408 # echo 1 > snapshot // current:1408, spare:123 # grep bytes per_cpu/cpu0/stats bytes: 1443700 # cat buffer_size_kb 123 // != current:1408 And also, a similar per-cpu case hits the following WARNING: Reproducer: # echo 1 > per_cpu/cpu0/snapshot # echo 123 > buffer_size_kb # echo 1 > per_cpu/cpu0/snapshot WARNING: WARNING: CPU: 0 PID: 1946 at kernel/trace/trace.c:1607 update_max_tr_single.part.0+0x2b8/0x380 Modules linked in: CPU: 0 PID: 1946 Comm: bash Not tainted 5.2.0-rc6 #20 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-2.fc30 04/01/2014 RIP: 0010:update_max_tr_single.part.0+0x2b8/0x380 Code: ff e8 dc da f9 ff 0f 0b e9 88 fe ff ff e8 d0 da f9 ff 44 89 ee bf f5 ff ff ff e8 33 dc f9 ff 41 83 fd f5 74 96 e8 b8 da f9 ff <0f> 0b eb 8d e8 af da f9 ff 0f 0b e9 bf fd ff ff e8 a3 da f9 ff 48 RSP: 0018:ffff888063e4fca0 EFLAGS: 00010093 RAX: ffff888066214380 RBX: ffffffff99850fe0 RCX: ffffffff964298a8 RDX: 0000000000000000 RSI: 00000000fffffff5 RDI: 0000000000000005 RBP: 1ffff1100c7c9f96 R08: ffff888066214380 R09: ffffed100c7c9f9b R10: ffffed100c7c9f9a R11: 0000000000000003 R12: 0000000000000000 R13: 00000000ffffffea R14: ffff888066214380 R15: ffffffff99851060 FS: 00007f9f8173c700(0000) GS:ffff88806d000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000714dc0 CR3: 0000000066fa6000 CR4: 00000000000006f0 Call Trace: ? trace_array_printk_buf+0x140/0x140 ? __mutex_lock_slowpath+0x10/0x10 tracing_snapshot_write+0x4c8/0x7f0 ? trace_printk_init_buffers+0x60/0x60 ? selinux_file_permission+0x3b/0x540 ? tracer_preempt_off+0x38/0x506 ? trace_printk_init_buffers+0x60/0x60 __vfs_write+0x81/0x100 vfs_write+0x1e1/0x560 ksys_write+0x126/0x250 ? __ia32_sys_read+0xb0/0xb0 ? do_syscall_64+0x1f/0x390 do_syscall_64+0xc1/0x390 entry_SYSCALL_64_after_hwframe+0x49/0xbe This patch adds resize_buffer_duplicate_size() to check if there is a difference between current/spare buffer sizes and resize a spare buffer if necessary. Link: http://lkml.kernel.org/r/20190625012910.13109-1-devel@etsukata.com Cc: stable@vger.kernel.org Fixes: ad909e21bbe69 ("tracing: Add internal tracing_snapshot() functions") Signed-off-by: Eiichi Tsukata <devel@etsukata.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tracing: Silence GCC 9 array bounds warningMiguel Ojeda2019-07-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 0c97bf863efce63d6ab7971dad811601e6171d2f upstream. Starting with GCC 9, -Warray-bounds detects cases when memset is called starting on a member of a struct but the size to be cleared ends up writing over further members. Such a call happens in the trace code to clear, at once, all members after and including `seq` on struct trace_iterator: In function 'memset', inlined from 'ftrace_dump' at kernel/trace/trace.c:8914:3: ./include/linux/string.h:344:9: warning: '__builtin_memset' offset [8505, 8560] from the object at 'iter' is out of the bounds of referenced subobject 'seq' with type 'struct trace_seq' at offset 4368 [-Warray-bounds] 344 | return __builtin_memset(p, c, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ In order to avoid GCC complaining about it, we compute the address ourselves by adding the offsetof distance instead of referring directly to the member. Since there are two places doing this clear (trace.c and trace_kdb.c), take the chance to move the workaround into a single place in the internal header. Link: http://lkml.kernel.org/r/20190523124535.GA12931@gmail.com Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> [ Removed unnecessary parenthesis around "iter" ] Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tracing: Fix partial reading of trace event's id fileElazar Leibovich2019-06-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit cbe08bcbbe787315c425dde284dcb715cfbf3f39 upstream. 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 cd458ba9d5a5 ("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: 23725aeeab10b ("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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* trace: Fix preempt_enable_no_resched() abusePeter Zijlstra2019-05-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit d6097c9e4454adf1f8f2c9547c2fa6060d55d952 upstream. Unless the very next line is schedule(), or implies it, one must not use preempt_enable_no_resched(). It can cause a preemption to go missing and thereby cause arbitrary delays, breaking the PREEMPT=y invariant. Link: http://lkml.kernel.org/r/20190423200318.GY14281@hirez.programming.kicks-ass.net Cc: Waiman Long <longman@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: the arch/x86 maintainers <x86@kernel.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: huang ying <huang.ying.caritas@gmail.com> Cc: Roman Gushchin <guro@fb.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: stable@vger.kernel.org Fixes: 2c2d7329d8af ("tracing/ftrace: use preempt_enable_no_resched_notrace in ring_buffer_time_stamp()") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* kprobes: Mark ftrace mcount handler functions nokprobeMasami Hiramatsu2019-04-27
| | | | | | | | | | | | | | | | | | | | | | | commit fabe38ab6b2bd9418350284c63825f13b8a6abba upstream. Mark ftrace mcount handler functions nokprobe since probing on these functions with kretprobe pushes return address incorrectly on kretprobe shadow stack. Reported-by: Francis Deslauriers <francis.deslauriers@efficios.com> Tested-by: Andrea Righi <righi.andrea@gmail.com> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/155094062044.6137.6419622920568680640.stgit@devbox Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tracing: kdb: Fix ftdump to not sleepDouglas Anderson2019-04-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit 31b265b3baaf55f209229888b7ffea523ddab366 ] As reported back in 2016-11 [1], the "ftdump" kdb command triggers a BUG for "sleeping function called from invalid context". kdb's "ftdump" command wants to call ring_buffer_read_prepare() in atomic context. A very simple solution for this is to add allocation flags to ring_buffer_read_prepare() so kdb can call it without triggering the allocation error. This patch does that. Note that in the original email thread about this, it was suggested that perhaps the solution for kdb was to either preallocate the buffer ahead of time or create our own iterator. I'm hoping that this alternative of adding allocation flags to ring_buffer_read_prepare() can be considered since it means I don't need to duplicate more of the core trace code into "trace_kdb.c" (for either creating my own iterator or re-preparing a ring allocator whose memory was already allocated). NOTE: another option for kdb is to actually figure out how to make it reuse the existing ftrace_dump() function and totally eliminate the duplication. This sounds very appealing and actually works (the "sr z" command can be seen to properly dump the ftrace buffer). The downside here is that ftrace_dump() fully consumes the trace buffer. Unless that is changed I'd rather not use it because it means "ftdump | grep xyz" won't be very useful to search the ftrace buffer since it will throw away the whole trace on the first grep. A future patch to dump only the last few lines of the buffer will also be hard to implement. [1] https://lkml.kernel.org/r/20161117191605.GA21459@google.com Link: http://lkml.kernel.org/r/20190308193205.213659-1-dianders@chromium.org Reported-by: Brian Norris <briannorris@chromium.org> Signed-off-by: Douglas Anderson <dianders@chromium.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
* tracing: Do not free iter->trace in fail path of tracing_open_pipe()zhangyi (F)2019-03-23
| | | | | | | | | | | | | | | | | | | | | commit e7f0c424d0806b05d6f47be9f202b037eb701707 upstream. Commit d716ff71dd12 ("tracing: Remove taking of trace_types_lock in pipe files") use the current tracer instead of the copy in tracing_open_pipe(), but it forget to remove the freeing sentence in the error path. There's an error path that can call kfree(iter->trace) after the iter->trace was assigned to tr->current_trace, which would be bad to free. Link: http://lkml.kernel.org/r/1550060946-45984-1-git-send-email-yi.zhang@huawei.com Cc: stable@vger.kernel.org Fixes: d716ff71dd12 ("tracing: Remove taking of trace_types_lock in pipe files") Signed-off-by: zhangyi (F) <yi.zhang@huawei.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tracing/uprobes: Fix output for multiple string argumentsAndreas Ziegler2019-02-20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 0722069a5374b904ec1a67f91249f90e1cfae259 upstream. When printing multiple uprobe arguments as strings the output for the earlier arguments would also include all later string arguments. This is best explained in an example: Consider adding a uprobe to a function receiving two strings as parameters which is at offset 0xa0 in strlib.so and we want to print both parameters when the uprobe is hit (on x86_64): $ echo 'p:func /lib/strlib.so:0xa0 +0(%di):string +0(%si):string' > \ /sys/kernel/debug/tracing/uprobe_events When the function is called as func("foo", "bar") and we hit the probe, the trace file shows a line like the following: [...] func: (0x7f7e683706a0) arg1="foobar" arg2="bar" Note the extra "bar" printed as part of arg1. This behaviour stacks up for additional string arguments. The strings are stored in a dynamically growing part of the uprobe buffer by fetch_store_string() after copying them from userspace via strncpy_from_user(). The return value of strncpy_from_user() is then directly used as the required size for the string. However, this does not take the terminating null byte into account as the documentation for strncpy_from_user() cleary states that it "[...] returns the length of the string (not including the trailing NUL)" even though the null byte will be copied to the destination. Therefore, subsequent calls to fetch_store_string() will overwrite the terminating null byte of the most recently fetched string with the first character of the current string, leading to the "accumulation" of strings in earlier arguments in the output. Fix this by incrementing the return value of strncpy_from_user() by one if we did not hit the maximum buffer size. Link: http://lkml.kernel.org/r/20190116141629.5752-1-andreas.ziegler@fau.de Cc: Ingo Molnar <mingo@redhat.com> Cc: stable@vger.kernel.org Fixes: 5baaa59ef09e ("tracing/probes: Implement 'memory' fetch method for uprobes") Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Andreas Ziegler <andreas.ziegler@fau.de> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tracing: Fix memory leak of instance function hash filtersSteven Rostedt (VMware)2018-12-21
| | | | | | | | | | | | | | | | | | | | | | | commit 2840f84f74035e5a535959d5f17269c69fa6edc5 upstream. The following commands will cause a memory leak: # cd /sys/kernel/tracing # mkdir instances/foo # echo schedule > instance/foo/set_ftrace_filter # rmdir instances/foo The reason is that the hashes that hold the filters to set_ftrace_filter and set_ftrace_notrace are not freed if they contain any data on the instance and the instance is removed. Found by kmemleak detector. Cc: stable@vger.kernel.org Fixes: 591dffdade9f ("ftrace: Allow for function tracing instance to filter functions") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tracing: Fix memory leak in set_trigger_filter()Steven Rostedt (VMware)2018-12-21
| | | | | | | | | | | | | | | | | | | | | | commit 3cec638b3d793b7cacdec5b8072364b41caeb0e1 upstream. When create_event_filter() fails in set_trigger_filter(), the filter may still be allocated and needs to be freed. The caller expects the data->filter to be updated with the new filter, even if the new filter failed (we could add an error message by setting set_str parameter of create_event_filter(), but that's another update). But because the error would just exit, filter was left hanging and nothing could free it. Found by kmemleak detector. Cc: stable@vger.kernel.org Fixes: bac5fb97a173a ("tracing: Add and use generic set_trigger_filter() implementation") Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* bpf: fix check of allowed specifiers in bpf_trace_printkMartynas Pumputis2018-12-17
| | | | | | | | | | | | | | [ Upstream commit 1efb6ee3edea57f57f9fb05dba8dcb3f7333f61f ] A format string consisting of "%p" or "%s" followed by an invalid specifier (e.g. "%p%\n" or "%s%") could pass the check which would make format_decode (lib/vsprintf.c) to warn. Fixes: 9c959c863f82 ("tracing: Allow BPF programs to call bpf_trace_printk()") Reported-by: syzbot+1ec5c5ec949c4adaa0c4@syzkaller.appspotmail.com Signed-off-by: Martynas Pumputis <m@lambda.lt> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
* tracing: Skip more functions when doing stack tracing of eventsSteven Rostedt (Red Hat)2018-11-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit be54f69c26193de31053190761e521903b89d098 ] # echo 1 > options/stacktrace # echo 1 > events/sched/sched_switch/enable # cat trace <idle>-0 [002] d..2 1982.525169: <stack trace> => save_stack_trace => __ftrace_trace_stack => trace_buffer_unlock_commit_regs => event_trigger_unlock_commit => trace_event_buffer_commit => trace_event_raw_event_sched_switch => __schedule => schedule => schedule_preempt_disabled => cpu_startup_entry => start_secondary The above shows that we are seeing 6 functions before ever making it to the caller of the sched_switch event. # echo stacktrace > events/sched/sched_switch/trigger # cat trace <idle>-0 [002] d..3 2146.335208: <stack trace> => trace_event_buffer_commit => trace_event_raw_event_sched_switch => __schedule => schedule => schedule_preempt_disabled => cpu_startup_entry => start_secondary The stacktrace trigger isn't as bad, because it adds its own skip to the stacktracing, but still has two events extra. One issue is that if the stacktrace passes its own "regs" then there should be no addition to the skip, as the regs will not include the functions being called. This was an issue that was fixed by commit 7717c6be6999 ("tracing: Fix stacktrace skip depth in trace_buffer_unlock_commit_regs()" as adding the skip number for kprobes made the probes not have any stack at all. But since this is only an issue when regs is being used, a skip should be added if regs is NULL. Now we have: # echo 1 > options/stacktrace # echo 1 > events/sched/sched_switch/enable # cat trace <idle>-0 [000] d..2 1297.676333: <stack trace> => __schedule => schedule => schedule_preempt_disabled => cpu_startup_entry => rest_init => start_kernel => x86_64_start_reservations => x86_64_start_kernel # echo stacktrace > events/sched/sched_switch/trigger # cat trace <idle>-0 [002] d..3 1370.759745: <stack trace> => __schedule => schedule => schedule_preempt_disabled => cpu_startup_entry => start_secondary And kprobes are not touched. Reported-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
* ring-buffer: Allow for rescheduling when removing pagesVaibhav Nagarnaik2018-09-29
| | | | | | | | | | | | | | | | | | | | | | | | | commit 83f365554e47997ec68dc4eca3f5dce525cd15c3 upstream. When reducing ring buffer size, pages are removed by scheduling a work item on each CPU for the corresponding CPU ring buffer. After the pages are removed from ring buffer linked list, the pages are free()d in a tight loop. The loop does not give up CPU until all pages are removed. In a worst case behavior, when lot of pages are to be freed, it can cause system stall. After the pages are removed from the list, the free() can happen while the work is rescheduled. Call cond_resched() in the loop to prevent the system hangup. Link: http://lkml.kernel.org/r/20180907223129.71994-1-vnagarnaik@google.com Cc: stable@vger.kernel.org Fixes: 83f40318dab00 ("ring-buffer: Make removal of ring buffer pages atomic") Reported-by: Jason Behmer <jbehmer@google.com> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* uprobes: Use synchronize_rcu() not synchronize_sched()Steven Rostedt (VMware)2018-09-09
| | | | | | | | | | | | | | | | | | | | commit 016f8ffc48cb01d1e7701649c728c5d2e737d295 upstream. While debugging another bug, I was looking at all the synchronize*() functions being used in kernel/trace, and noticed that trace_uprobes was using synchronize_sched(), with a comment to synchronize with {u,ret}_probe_trace_func(). When looking at those functions, the data is protected with "rcu_read_lock()" and not with "rcu_read_lock_sched()". This is using the wrong synchronize_*() function. Link: http://lkml.kernel.org/r/20180809160553.469e1e32@gandalf.local.home Cc: stable@vger.kernel.org Fixes: 70ed91c6ec7f8 ("tracing/uprobes: Support ftrace_event_file base multibuffer") Acked-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tracing/blktrace: Fix to allow setting same valueSteven Rostedt (VMware)2018-09-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 757d9140072054528b13bbe291583d9823cde195 upstream. Masami Hiramatsu reported: Current trace-enable attribute in sysfs returns an error if user writes the same setting value as current one, e.g. # cat /sys/block/sda/trace/enable 0 # echo 0 > /sys/block/sda/trace/enable bash: echo: write error: Invalid argument # echo 1 > /sys/block/sda/trace/enable # echo 1 > /sys/block/sda/trace/enable bash: echo: write error: Device or resource busy But this is not a preferred behavior, it should ignore if new setting is same as current one. This fixes the problem as below. # cat /sys/block/sda/trace/enable 0 # echo 0 > /sys/block/sda/trace/enable # echo 1 > /sys/block/sda/trace/enable # echo 1 > /sys/block/sda/trace/enable Link: http://lkml.kernel.org/r/20180816103802.08678002@gandalf.local.home Cc: Ingo Molnar <mingo@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: linux-block@vger.kernel.org Cc: stable@vger.kernel.org Fixes: cd649b8bb830d ("blktrace: remove sysfs_blk_trace_enable_show/store()") Reported-by: Masami Hiramatsu <mhiramat@kernel.org> Tested-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tracing: Do not call start/stop() functions when tracing_on does not changeSteven Rostedt (VMware)2018-09-09
| | | | | | | | | | | | | | | | | | | | commit f143641bfef9a4a60c57af30de26c63057e7e695 upstream. Currently, when one echo's in 1 into tracing_on, the current tracer's "start()" function is executed, even if tracing_on was already one. This can lead to strange side effects. One being that if the hwlat tracer is enabled, and someone does "echo 1 > tracing_on" into tracing_on, the hwlat tracer's start() function is called again which will recreate another kernel thread, and make it unable to remove the old one. Link: http://lkml.kernel.org/r/1533120354-22923-1-git-send-email-erica.bugden@linutronix.de Cc: stable@vger.kernel.org Fixes: 2df8f8a6a897e ("tracing: Fix regression with irqsoff tracer and tracing_on file") Reported-by: Erica Bugden <erica.bugden@linutronix.de> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tracing: Use __printf markup to silence compilerMathieu Malaterre2018-08-24
| | | | | | | | | | | | | | | | | | | | [ Upstream commit 26b68dd2f48fe7699a89f0cfbb9f4a650dc1c837 ] Silence warnings (triggered at W=1) by adding relevant __printf attributes. CC kernel/trace/trace.o kernel/trace/trace.c: In function ‘__trace_array_vprintk’: kernel/trace/trace.c:2979:2: warning: function might be possible candidate for ‘gnu_printf’ format attribute [-Wsuggest-attribute=format] len = vscnprintf(tbuffer, TRACE_BUF_SIZE, fmt, args); ^~~ AR kernel/trace/built-in.o Link: http://lkml.kernel.org/r/20180308205843.27447-1-malat@debian.org Signed-off-by: Mathieu Malaterre <malat@debian.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* ring_buffer: tracing: Inherit the tracing setting to next ring bufferMasami Hiramatsu2018-08-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 73c8d8945505acdcbae137c2e00a1232e0be709f upstream. Maintain the tracing on/off setting of the ring_buffer when switching to the trace buffer snapshot. Taking a snapshot is done by swapping the backup ring buffer (max_tr_buffer). But since the tracing on/off setting is defined by the ring buffer, when swapping it, the tracing on/off setting can also be changed. This causes a strange result like below: /sys/kernel/debug/tracing # cat tracing_on 1 /sys/kernel/debug/tracing # echo 0 > tracing_on /sys/kernel/debug/tracing # cat tracing_on 0 /sys/kernel/debug/tracing # echo 1 > snapshot /sys/kernel/debug/tracing # cat tracing_on 1 /sys/kernel/debug/tracing # echo 1 > snapshot /sys/kernel/debug/tracing # cat tracing_on 0 We don't touch tracing_on, but snapshot changes tracing_on setting each time. This is an anomaly, because user doesn't know that each "ring_buffer" stores its own tracing-enable state and the snapshot is done by swapping ring buffers. Link: http://lkml.kernel.org/r/153149929558.11274.11730609978254724394.stgit@devbox Cc: Ingo Molnar <mingo@redhat.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Tom Zanussi <tom.zanussi@linux.intel.com> Cc: Hiraku Toyooka <hiraku.toyooka@cybertrust.co.jp> Cc: stable@vger.kernel.org Fixes: debdd57f5145 ("tracing: Make a snapshot feature available from userspace") Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> [ Updated commit log and comment in the code ] Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tracing: Quiet gcc warning about maybe unused link variableSteven Rostedt (VMware)2018-08-06
| | | | | | | | | | | | | | | | | | | | | | | commit 2519c1bbe38d7acacc9aacba303ca6f97482ed53 upstream. Commit 57ea2a34adf4 ("tracing/kprobes: Fix trace_probe flags on enable_trace_kprobe() failure") added an if statement that depends on another if statement that gcc doesn't see will initialize the "link" variable and gives the warning: "warning: 'link' may be used uninitialized in this function" It is really a false positive, but to quiet the warning, and also to make sure that it never actually is used uninitialized, initialize the "link" variable to NULL and add an if (!WARN_ON_ONCE(!link)) where the compiler thinks it could be used uninitialized. Cc: stable@vger.kernel.org Fixes: 57ea2a34adf4 ("tracing/kprobes: Fix trace_probe flags on enable_trace_kprobe() failure") Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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