- 23 Nov, 2019 7 commits
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Hassan Naveed authored
Since MIPS architecture has a sparse syscall array, select the HAVE_SPARSE_SYSCALL_NR to save space. Link: http://lkml.kernel.org/r/20191115234314.21599-2-hnaveed@wavecomp.comSigned-off-by:
Hassan Naveed <hnaveed@wavecomp.com> Reviewed-by:
Paul Burton <paulburton@kernel.org> Signed-off-by:
Steven Rostedt (VMware) <rostedt@goodmis.org>
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Hassan Naveed authored
Currently, a lot of memory is wasted for architectures like MIPS when init_ftrace_syscalls() allocates the array for syscalls using kcalloc. This is because syscalls numbers start from 4000, 5000 or 6000 and array elements up to that point are unused. Fix this by using a data structure more suited to storing sparsely populated arrays. The XARRAY data structure, implemented using radix trees, is much more memory efficient for storing the syscalls in question. Link: http://lkml.kernel.org/r/20191115234314.21599-1-hnaveed@wavecomp.comSigned-off-by:
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Divya Indi authored
This is a sample module to demonstrate the use of the newly introduced and exported APIs to access Ftrace instances from within the kernel. Newly introduced APIs used here - 1. Create/Lookup a trace array with the given name. struct trace_array *trace_array_get_by_name(const char *name) 2. Destroy/Remove a trace array. int trace_array_destroy(struct trace_array *tr) 4. Enable/Disable trace events: int trace_array_set_clr_event(struct trace_array *tr, const char *system, const char *event, bool enable); Exported APIs - 1. trace_printk equivalent for instances. int trace_array_printk(struct trace_array *tr, unsigned long ip, const char *fmt, ...); 2. Helper function. void trace_printk_init_buffers(void); 3. To decrement the reference counter. void trace_array_put(struct trace_array *tr) Sample output(contents of /sys/kernel/tracing/instances/sample-instance) NOTE: Tracing disabled after ~5 sec) _-----=> irqs-off / _----=> need-resched | / _---=> hardirq/softirq || / _--=> preempt-depth ||| / delay TASK-PID CPU# |||| TIMESTAMP FUNCTION | | | |||| | | sample-instance-1452 [002] .... 49.430948: simple_thread: trace_array_printk: count=0 sample-instance-1452 [002] .... 49.430951: sample_event: count value=0 at jiffies=4294716608 sample-instance-1452 [002] .... 50.454847: simple_thread: trace_array_printk: count=1 sample-instance-1452 [002] .... 50.454849: sample_event: count value=1 at jiffies=4294717632 sample-instance-1452 [002] .... 51.478748: simple_thread: trace_array_printk: count=2 sample-instance-1452 [002] .... 51.478750: sample_event: count value=2 at jiffies=4294718656 sample-instance-1452 [002] .... 52.502652: simple_thread: trace_array_printk: count=3 sample-instance-1452 [002] .... 52.502655: sample_event: count value=3 at jiffies=4294719680 sample-instance-1452 [002] .... 53.526533: simple_thread: trace_array_printk: count=4 sample-instance-1452 [002] .... 53.526535: sample_event: count value=4 at jiffies=4294720704 sample-instance-1452 [002] .... 54.550438: simple_thread: trace_array_printk: count=5 sample-instance-1452 [002] .... 55.574336: simple_thread: trace_array_printk: count=6 Link: http://lkml.kernel.org/r/1574276919-11119-3-git-send-email-divya.indi@oracle.comReviewed-by:Aruna Ramakrishna <aruna.ramakrishna@oracle.com> Signed-off-by:
Divya Indi <divya.indi@oracle.com> [ Moved to samples/ftrace ] Signed-off-by:
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Divya Indi authored
Adding 2 new functions - 1) struct trace_array *trace_array_get_by_name(const char *name); Return pointer to a trace array with given name. If it does not exist, create and return pointer to the new trace array. 2) int trace_array_set_clr_event(struct trace_array *tr, const char *system ,const char *event, bool enable); Enable/Disable events to this trace array. Additionally, - To handle reference counters, export trace_array_put() - Due to introduction of the above 2 new functions, we no longer need to export - ftrace_set_clr_event & trace_array_create APIs. Link: http://lkml.kernel.org/r/1574276919-11119-2-git-send-email-divya.indi@oracle.comSigned-off-by:
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Krzysztof Kozlowski authored
Adjust indentation from spaces to tab (+optional two spaces) as in coding style with command like: $ sed -e 's/^ /\t/' -i */Kconfig Link: http://lkml.kernel.org/r/20191120133807.12741-1-krzk@kernel.orgSigned-off-by:
Krzysztof Kozlowski <krzk@kernel.org> Signed-off-by:
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Xianting Tian authored
Fix spelling and other typos Link: http://lkml.kernel.org/r/1573916755-32478-1-git-send-email-xianting_tian@126.comSigned-off-by:
Xianting Tian <xianting_tian@126.com> Signed-off-by:
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Enrico Weigelt, metux IT consult authored
It's cleaner to use the BIT() macro instead of raw shift operation. Link: http://lkml.kernel.org/r/20191121133815.15040-1-info@metux.netSigned-off-by:
Enrico Weigelt, metux IT consult <info@metux.net> [ Added BIT() for bits 16 and 17 ] Signed-off-by:
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- 20 Nov, 2019 1 commit
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Alexei Starovoitov authored
When CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS is not set it's best to have the stub functions return ENOTSUPP instead of ENODEV, otherwise ENODEV is a valid error when ip is incorrect which is indistinguishable from ftrace not compiled in. Link: http://lkml.kernel.org/r/CAADnVQ+OzTikM9EhrfsC7NFsVYhATW1SVHxK64w3xn9qpk81pg@mail.gmail.comSigned-off-by:
Alexei Starovoitov <ast@kernel.org> Signed-off-by:
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- 18 Nov, 2019 2 commits
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Steven Rostedt (VMware) authored
The ftrace_graph_stub was created and points to ftrace_stub as a way to assign the functon graph tracer function pointer to a stub function with a different prototype than what ftrace_stub has and not trigger the C verifier. The ftrace_graph_stub was created via the linker script vmlinux.lds.h. Unfortunately, powerpc already uses the name ftrace_graph_stub for its internal implementation of the function graph tracer, and even though powerpc would still build, the change via the linker script broke function tracer on powerpc from working. By using the name ftrace_stub_graph, which does not exist anywhere else in the kernel, this should not be a problem. Link: https://lore.kernel.org/r/1573849732.5937.136.camel@lca.pw Fixes: b83b43ff ("fgraph: Fix function type mismatches of ftrace_graph_return using ftrace_stub") Reorted-by:
Qian Cai <cai@lca.pw> Signed-off-by:
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Steven Rostedt (VMware) authored
If a direct ftrace callback is at a location that does not have any other ftrace helpers attached to it, it is possible to simply just change the text to call the new caller (if the architecture supports it). But this requires special architecture code. Currently, modify_ftrace_direct() uses a trick to add a stub ftrace callback to the location forcing it to call the ftrace iterator. Then it can change the direct helper to call the new function in C, and then remove the stub. Removing the stub will have the location now call the new location that the direct helper is using. The new helper function does the registering the stub trick, but is a weak function, allowing an architecture to override it to do something a bit more direct. Link: https://lore.kernel.org/r/20191115215125.mbqv7taqnx376yed@ast-mbp.dhcp.thefacebook.comSuggested-by:
Alexei Starovoitov <alexei.starovoitov@gmail.com> Signed-off-by:
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- 15 Nov, 2019 8 commits
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Steven Rostedt (VMware) authored
Both unregister_ftrace_direct() and modify_ftrace_direct() needs to normalize the ip passed in to match the rec->ip, as it is acceptable to have the ip on the ftrace call site but not the start. There are also common validity checks with the record found by the ip, these should be done for both unregister_ftrace_direct() and modify_ftrace_direct(). Signed-off-by: -
Steven Rostedt (VMware) authored
As an instruction pointer passed into register_ftrace_direct() may just exist on the ftrace call site, but may not be the start of the call site itself, register_ftrace_direct() still needs to update test if a direct call exists on the normalized site, as only one direct call is allowed at any one time. Fixes: 763e34e7 ("ftrace: Add register_ftrace_direct()") Signed-off-by:
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Steven Rostedt (VMware) authored
The direct->count wasn't being updated properly, where it only was updated when the first entry was added, but should be updated every time. Fixes: 013bf0da ("ftrace: Add ftrace_find_direct_func()") Signed-off-by:
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Colin Ian King authored
There is a spelling mistake in a trace_printk message. As well as in the selftests that search for this string. Link: http://lkml.kernel.org/r/20191115085938.38947-1-colin.king@canonical.com Link: http://lkml.kernel.org/r/20191115090356.39572-1-colin.king@canonical.comSigned-off-by:
Colin Ian King <colin.king@canonical.com> Signed-off-by:
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Artem Bityutskiy authored
Increase the maximum allowed count of synthetic event fields from 16 to 32 in order to allow for larger-than-usual events. Link: http://lkml.kernel.org/r/20191115091730.9192-1-dedekind1@gmail.comReviewed-by:
Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by:
Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Signed-off-by:
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Steven Rostedt (VMware) authored
Add a sample module that tests modify_ftrace_direct(), and this can be used by the selftests as well. Signed-off-by: -
Steven Rostedt (VMware) authored
Add a new function modify_ftrace_direct() that will allow a user to update an existing direct caller to a new trampoline, without missing hits due to unregistering one and then adding another. Link: https://lore.kernel.org/r/20191109022907.6zzo6orhxpt5n2sv@ast-mbp.dhcp.thefacebook.comSuggested-by:
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Steven Rostedt (VMware) authored
The latency_fsnotify() stub when the function is not defined, was missing the "inline". Link: https://lore.kernel.org/r/20191115140213.74c5efe7@canb.auug.org.auReported-by:
Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by:
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- 14 Nov, 2019 11 commits
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Borislav Petkov authored
There was a stray tab in the help text of the aforementioned config option which showed like this: The "print fmt" of the trace events will show the enum/sizeof names instead of their values. This can cause problems for user space tools ... in menuconfig. Remove it and end a sentence with a fullstop. No functional changes. Link: http://lkml.kernel.org/r/20191112174219.10933-1-bp@alien8.deSigned-off-by:
Borislav Petkov <bp@suse.de> Signed-off-by:
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Piotr Maziarz authored
Without this, buffers can be printed with __print_array macro that has no formatting options and can be hard to read. The other way is to mimic formatting capability with multiple calls of trace event with one call per row which gives performance impact and different timestamp in each row. Link: http://lkml.kernel.org/r/1573130738-29390-2-git-send-email-piotrx.maziarz@linux.intel.comSigned-off-by:
Piotr Maziarz <piotrx.maziarz@linux.intel.com> Signed-off-by:
Cezary Rojewski <cezary.rojewski@intel.com> Signed-off-by:
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Piotr Maziarz authored
Provided function is an analogue of print_hex_dump(). Implementing this function in seq_buf allows using for multiple purposes (e.g. for tracing) and therefore prevents from code duplication in every layer that uses seq_buf. print_hex_dump() is an essential part of logging data to dmesg. Adding similar capability for other purposes is beneficial to all users. Example usage: seq_buf_hex_dump(seq, "", DUMP_PREFIX_OFFSET, 16, 4, buf, ARRAY_SIZE(buf), true); Example output: 00000000: 00000000 ffffff10 ffffff32 ffff3210 ........2....2.. 00000010: ffff3210 83d00437 c0700000 00000000 .2..7.....p..... 00000020: 02010004 0000000f 0000000f 00004002 .............@.. 00000030: 00000fff 00000000 ........ Link: http://lkml.kernel.org/r/1573130738-29390-1-git-send-email-piotrx.maziarz@linux.intel.comSigned-off-by:
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Masami Hiramatsu authored
Check whether the non-suffixed symbol is notrace, since suffixed symbols are generated by the compilers for optimization. Based on these suffixed symbols, notrace check might not work because some of them are just a partial code of the original function. (e.g. cold-cache (unlikely) code is separated from original function as FUNCTION.cold.XX) For example, without this fix, # echo p device_add.cold.67 > /sys/kernel/debug/tracing/kprobe_events sh: write error: Invalid argument # cat /sys/kernel/debug/tracing/error_log [ 135.491035] trace_kprobe: error: Failed to register probe event Command: p device_add.cold.67 ^ # dmesg | tail -n 1 [ 135.488599] trace_kprobe: Could not probe notrace function device_add.cold.67 With this, # echo p device_add.cold.66 > /sys/kernel/debug/tracing/kprobe_events # cat /sys/kernel/debug/kprobes/list ffffffff81599de9 k device_add.cold.66+0x0 [DISABLED] Actually, kprobe blacklist already did similar thing, see within_kprobe_blacklist(). Link: http://lkml.kernel.org/r/157233790394.6706.18243942030937189679.stgit@devnote2 Fixes: 45408c4f ("tracing: kprobes: Prohibit probing on notrace function") Signed-off-by:Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by:
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Yuming Han authored
Fail to allocate memory for tgid_map, because it requires order-6 page. detail as: c3 sh: page allocation failure: order:6, mode:0x140c0c0(GFP_KERNEL), nodemask=(null) c3 sh cpuset=/ mems_allowed=0 c3 CPU: 3 PID: 5632 Comm: sh Tainted: G W O 4.14.133+ #10 c3 Hardware name: Generic DT based system c3 Backtrace: c3 [<c010bdbc>] (dump_backtrace) from [<c010c08c>](show_stack+0x18/0x1c) c3 [<c010c074>] (show_stack) from [<c0993c54>](dump_stack+0x84/0xa4) c3 [<c0993bd0>] (dump_stack) from [<c0229858>](warn_alloc+0xc4/0x19c) c3 [<c0229798>] (warn_alloc) from [<c022a6e4>](__alloc_pages_nodemask+0xd18/0xf28) c3 [<c02299cc>] (__alloc_pages_nodemask) from [<c0248344>](kmalloc_order+0x20/0x38) c3 [<c0248324>] (kmalloc_order) from [<c0248380>](kmalloc_order_trace+0x24/0x108) c3 [<c024835c>] (kmalloc_order_trace) from [<c01e6078>](set_tracer_flag+0xb0/0x158) c3 [<c01e5fc8>] (set_tracer_flag) from [<c01e6404>](trace_options_core_write+0x7c/0xcc) c3 [<c01e6388>] (trace_options_core_write) from [<c0278b1c>](__vfs_write+0x40/0x14c) c3 [<c0278adc>] (__vfs_write) from [<c0278e10>](vfs_write+0xc4/0x198) c3 [<c0278d4c>] (vfs_write) from [<c027906c>](SyS_write+0x6c/0xd0) c3 [<c0279000>] (SyS_write) from [<c01079a0>](ret_fast_syscall+0x0/0x54) Switch to use kvcalloc to avoid unexpected allocation failures. Link: http://lkml.kernel.org/r/1571888070-24425-1-git-send-email-chunyan.zhang@unisoc.comSigned-off-by:
Yuming Han <yuming.han@unisoc.com> Signed-off-by:
Chunyan Zhang <chunyan.zhang@unisoc.com> Signed-off-by:
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Srivatsa S. Bhat (VMware) authored
Update the source file name in the comments, and fix a grammatical error. Link: http://lkml.kernel.org/r/157073346821.17189.8946944856026592247.stgit@srivatsa-ubuntuSigned-off-by:
Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu> Signed-off-by:
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Andy Shevchenko authored
Comparator function type, cmp_func_t, is defined in the types.h, use it in the code. Link: http://lkml.kernel.org/r/20191007135656.37734-3-andriy.shevchenko@linux.intel.comSigned-off-by:
Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by:
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Andy Shevchenko authored
Comparator function type, cmp_func_t, is defined in the types.h, use it in bsearch() and, thus, add more sense to the corresponding comment in the code. Link: http://lkml.kernel.org/r/20191007135656.37734-2-andriy.shevchenko@linux.intel.comSigned-off-by:
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Andy Shevchenko authored
The function types for swap, cmp and cmp_r functions are already being in use by modules. Move them to types.h that everybody in kernel will be able to use generic types instead of custom ones. This adds more sense to the comment in bsearch() later on. Link: http://lkml.kernel.org/r/20191007135656.37734-1-andriy.shevchenko@linux.intel.comSigned-off-by:
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Steven Rostedt (VMware) authored
As the ftrace selftests can run for a long period of time, disable the timeout that the general selftests have. If a selftest hangs, then it probably means the machine will hang too. Link: https://lore.kernel.org/r/alpine.LSU.2.21.1911131604170.18679@pobox.suse.czSuggested-by:
Miroslav Benes <mbenes@suse.cz> Tested-by:
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Steven Rostedt (VMware) authored
The C compiler is allowing more checks to make sure that function pointers are assigned to the correct prototype function. Unfortunately, the function graph tracer uses a special name with its assigned ftrace_graph_return function pointer that maps to a stub function used by the function tracer (ftrace_stub). The ftrace_graph_return variable is compared to the ftrace_stub in some archs to know if the function graph tracer is enabled or not. This means we can not just simply create a new function stub that compares it without modifying all the archs. Instead, have the linker script create a function_graph_stub that maps to ftrace_stub, and this way we can define the prototype for it to match the prototype of ftrace_graph_return, and make the compiler checks all happy! Link: http://lkml.kernel.org/r/20191015090055.789a0aed@gandalf.local.home Cc: linux-sh@vger.kernel.org Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Rich Felker <dalias@libc.org> Reported-by:
Sami Tolvanen <samitolvanen@google.com> Signed-off-by:
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- 13 Nov, 2019 11 commits
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Divya Indi authored
As part of commit f45d1225 ("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.comSigned-off-by:
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Divya Indi authored
A trace array can be destroyed from userspace or kernel. Verify if the trace array exists before proceeding to destroy/remove it. Link: http://lkml.kernel.org/r/1565805327-579-3-git-send-email-divya.indi@oracle.comReviewed-by:
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Divya Indi authored
Declare the newly introduced and exported APIs in the header file - include/linux/trace.h. Moving previous declarations from kernel/trace/trace.h to include/linux/trace.h. Link: http://lkml.kernel.org/r/1565805327-579-2-git-send-email-divya.indi@oracle.comSigned-off-by:
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Ben Dooks authored
The event_class_ftrace_##call and event_##call do not seem to be used outside of trace_export.c so make them both static to avoid a number of sparse warnings: kernel/trace/trace_entries.h:59:1: warning: symbol 'event_class_ftrace_function' was not declared. Should it be static? kernel/trace/trace_entries.h:59:1: warning: symbol '__event_function' was not declared. Should it be static? kernel/trace/trace_entries.h:77:1: warning: symbol 'event_class_ftrace_funcgraph_entry' was not declared. Should it be static? kernel/trace/trace_entries.h:77:1: warning: symbol '__event_funcgraph_entry' was not declared. Should it be static? kernel/trace/trace_entries.h:93:1: warning: symbol 'event_class_ftrace_funcgraph_exit' was not declared. Should it be static? kernel/trace/trace_entries.h:93:1: warning: symbol '__event_funcgraph_exit' was not declared. Should it be static? kernel/trace/trace_entries.h:129:1: warning: symbol 'event_class_ftrace_context_switch' was not declared. Should it be static? kernel/trace/trace_entries.h:129:1: warning: symbol '__event_context_switch' was not declared. Should it be static? kernel/trace/trace_entries.h:149:1: warning: symbol 'event_class_ftrace_wakeup' was not declared. Should it be static? kernel/trace/trace_entries.h:149:1: warning: symbol '__event_wakeup' was not declared. Should it be static? kernel/trace/trace_entries.h:171:1: warning: symbol 'event_class_ftrace_kernel_stack' was not declared. Should it be static? kernel/trace/trace_entries.h:171:1: warning: symbol '__event_kernel_stack' was not declared. Should it be static? kernel/trace/trace_entries.h:191:1: warning: symbol 'event_class_ftrace_user_stack' was not declared. Should it be static? kernel/trace/trace_entries.h:191:1: warning: symbol '__event_user_stack' was not declared. Should it be static? kernel/trace/trace_entries.h:214:1: warning: symbol 'event_class_ftrace_bprint' was not declared. Should it be static? kernel/trace/trace_entries.h:214:1: warning: symbol '__event_bprint' was not declared. Should it be static? kernel/trace/trace_entries.h:230:1: warning: symbol 'event_class_ftrace_print' was not declared. Should it be static? kernel/trace/trace_entries.h:230:1: warning: symbol '__event_print' was not declared. Should it be static? kernel/trace/trace_entries.h:247:1: warning: symbol 'event_class_ftrace_raw_data' was not declared. Should it be static? kernel/trace/trace_entries.h:247:1: warning: symbol '__event_raw_data' was not declared. Should it be static? kernel/trace/trace_entries.h:262:1: warning: symbol 'event_class_ftrace_bputs' was not declared. Should it be static? kernel/trace/trace_entries.h:262:1: warning: symbol '__event_bputs' was not declared. Should it be static? kernel/trace/trace_entries.h:277:1: warning: symbol 'event_class_ftrace_mmiotrace_rw' was not declared. Should it be static? kernel/trace/trace_entries.h:277:1: warning: symbol '__event_mmiotrace_rw' was not declared. Should it be static? kernel/trace/trace_entries.h:298:1: warning: symbol 'event_class_ftrace_mmiotrace_map' was not declared. Should it be static? kernel/trace/trace_entries.h:298:1: warning: symbol '__event_mmiotrace_map' was not declared. Should it be static? kernel/trace/trace_entries.h:322:1: warning: symbol 'event_class_ftrace_branch' was not declared. Should it be static? kernel/trace/trace_entries.h:322:1: warning: symbol '__event_branch' was not declared. Should it be static? kernel/trace/trace_entries.h:343:1: warning: symbol 'event_class_ftrace_hwlat' was not declared. Should it be static? kernel/trace/trace_entries.h:343:1: warning: symbol '__event_hwlat' was not declared. Should it be static? Link: http://lkml.kernel.org/r/20191015121012.18824-1-ben.dooks@codethink.co.ukSigned-off-by:
Ben Dooks <ben.dooks@codethink.co.uk> Signed-off-by:
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Sebastian Andrzej Siewior authored
CONFIG_PREEMPTION is selected by CONFIG_PREEMPT and by CONFIG_PREEMPT_RT. Both PREEMPT and PREEMPT_RT require the same functionality which today depends on CONFIG_PREEMPT. Add additional header output for PREEMPT_RT. Link: http://lkml.kernel.org/r/20191015191821.11479-34-bigeasy@linutronix.de Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by:
Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by:
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Viktor Rosendahl (BMW) authored
This burst feature enables the user to generate a burst of preempt/irqsoff latencies. This makes it possible to test whether we are able to detect latencies that systematically occur very close to each other. The maximum burst size is 10. We also create 10 identical test functions, so that we get 10 different backtraces; this is useful when we want to test whether we can detect all the latencies in a burst. Otherwise, there would be no easy way of differentiating between which latency in a burst was captured by the tracer. In addition, there is a sysfs trigger, so that it's not necessary to reload the module to repeat the test. The trigger will appear as /sys/kernel/preemptirq_delay_test/trigger in sysfs. Link: http://lkml.kernel.org/r/20191008220824.7911-3-viktor.rosendahl@gmail.comReviewed-by:
Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by:
Viktor Rosendahl (BMW) <viktor.rosendahl@gmail.com> Signed-off-by:
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Viktor Rosendahl (BMW) authored
This patch implements the feature that the tracing_max_latency file, e.g. /sys/kernel/debug/tracing/tracing_max_latency will receive notifications through the fsnotify framework when a new latency is available. One particularly interesting use of this facility is when enabling threshold tracing, through /sys/kernel/debug/tracing/tracing_thresh, together with the preempt/irqsoff tracers. This makes it possible to implement a user space program that can, with equal probability, obtain traces of latencies that occur immediately after each other in spite of the fact that the preempt/irqsoff tracers operate in overwrite mode. This facility works with the hwlat, preempt/irqsoff, and wakeup tracers. The tracers may call the latency_fsnotify() from places such as __schedule() or do_idle(); this makes it impossible to call queue_work() directly without risking a deadlock. The same would happen with a softirq, kernel thread or tasklet. For this reason we use the irq_work mechanism to call queue_work(). This patch creates a new workqueue. The reason for doing this is that I wanted to use the WQ_UNBOUND and WQ_HIGHPRI flags. My thinking was that WQ_UNBOUND might help with the latency in some important cases. If we use: queue_work(system_highpri_wq, &tr->fsnotify_work); then the work will (almost) always execute on the same CPU but if we are unlucky that CPU could be too busy while there could be another CPU in the system that would be able to process the work soon enough. queue_work_on() could be used to queue the work on another CPU but it seems difficult to select the right CPU. Link: http://lkml.kernel.org/r/20191008220824.7911-2-viktor.rosendahl@gmail.comReviewed-by:
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Steven Rostedt (VMware) authored
Looking for ways to shrink the size of the dyn_ftrace structure, knowing the information about how many pages and the number of groups of those pages, is useful in working out the best ways to save on memory. This adds one info print on how many groups of pages were used to allocate the ftrace dyn_ftrace structures, and also shows the number of pages and groups in the dyn_ftrace_total_info (which is used for debugging). Signed-off-by: -
Josh Poimboeuf authored
Objtool complains about the new ftrace direct trampoline code: arch/x86/kernel/ftrace_64.o: warning: objtool: ftrace_regs_caller()+0x190: stack state mismatch: cfa1=7+16 cfa2=7+24 Typically, code has a deterministic stack layout, such that at a given instruction address, the stack frame size is always the same. That's not the case for the new ftrace_regs_caller() code after it adjusts the stack for the direct case. Just plead ignorance and assume it's always the non-direct path. Note this creates a tiny window for ORC to get confused. Link: http://lkml.kernel.org/r/20191108225100.ea3bhsbdf6oerj6g@trebleReported-by:
Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by:
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Steven Rostedt (VMware) authored
As testing for direct calls from the function graph tracer adds a little overhead (which is a lot when tracing every function), add a counter that can be used to test if function_graph tracer needs to test for a direct caller or not. It would have been nicer if we could use a static branch, but the static branch logic fails when used within the function graph tracer trampoline. Signed-off-by: -
Steven Rostedt (VMware) authored
Enable x86 to allow for register_ftrace_direct(), where a custom trampoline may be called directly from an ftrace mcount/fentry location. Signed-off-by:
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