Pull more tracing updates from Steven Rostedt:
- Add trace flag for NEED_RESCHED_LAZY
Now that NEED_RESCHED_LAZY is upstream, add it to the status bits of
the common_flags. This will now show when the NEED_RESCHED_LAZY flag
is set that is used for debugging latency issues in the kernel via a
trace.
- Remove leftover "__idx" variable when SRCU was removed from the
tracepoint code
- Add rcu_tasks_trace guard
To add a guard() around the tracepoint code, a rcu_tasks_trace guard
needs to be created first.
- Remove __DO_TRACE() macro and just call __DO_TRACE_CALL() directly
The DO_TRACE() macro has conditional locking depending on what was
passed into the macro parameters. As the guts of the macro has been
moved to __DO_TRACE_CALL() to handle static call logic, there's no
reason to keep the __DO_TRACE() macro around.
It is better to just do the locking in place without the conditionals
and call __DO_TRACE_CALL() from those locations. The "cond" passed in
can also be moved out of that macro. This simplifies the code.
- Remove the "cond" from the system call tracepoint macros
The "cond" variable was added to allow some tracepoints to check a
condition within the static_branch (jump/nop) logic. The system calls
do not need this. Removing it simplifies the code.
- Replace scoped_guard() with just guard() in the tracepoint logic
guard() works just as well as scoped_guard() in the tracepoint logic
and the scoped_guard() causes some issues.
* tag 'trace-v6.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing: Use guard() rather than scoped_guard()
tracing: Remove cond argument from __DECLARE_TRACE_SYSCALL
tracing: Remove conditional locking from __DO_TRACE()
rcupdate_trace: Define rcu_tasks_trace lock guard
tracing: Remove __idx variable from __DO_TRACE
tracing: Move it_func[0] comment to the relevant context
tracing: Record task flag NEED_RESCHED_LAZY.
Pull rust trace event support from Steven Rostedt:
"Allow Rust code to have trace events
Trace events is a popular way to debug what is happening inside the
kernel or just to find out what is happening. Rust code is being added
to the Linux kernel but it currently does not support the tracing
infrastructure. Add support of trace events inside Rust code"
* tag 'trace-rust-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
rust: jump_label: skip formatting generated file
jump_label: rust: pass a mut ptr to `static_key_count`
samples: rust: fix `rust_print` build making it a combined module
rust: add arch_static_branch
jump_label: adjust inline asm to be consistent
rust: samples: add tracepoint to Rust sample
rust: add tracepoint support
rust: add static_branch_unlikely for static_key_false
Add for_each_tracepoint_in_module() function to iterate tracepoints in
a module. This API is needed for handling tracepoints in a loading
module from tracepoint_module_notifier callback function.
This also update for_each_module_tracepoint() to pass the module to
callback function so that it can find module easily.
Link: https://lore.kernel.org/all/172397778740.286558.15781131277732977643.stgit@devnote2/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
There are two WARN_ON*() warnings in tracepoint.h that deal with RCU
usage. But when they trigger, especially from using a TRACE_EVENT()
macro, the information is not very helpful and is confusing:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 0 at include/trace/events/lock.h:24 lock_acquire+0x2b2/0x2d0
Where the above warning takes you to:
TRACE_EVENT(lock_acquire, <<<--- line 24 in lock.h
TP_PROTO(struct lockdep_map *lock, unsigned int subclass,
int trylock, int read, int check,
struct lockdep_map *next_lock, unsigned long ip),
[..]
Change the WARN_ON_ONCE() to WARN_ONCE() and add a string that allows
someone to search for exactly where the bug happened.
Link: https://lore.kernel.org/linux-trace-kernel/20240228133112.0d64fb1b@gandalf.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Borislav Petkov <bp@alien8.de>
Tested-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Allow fprobe_events to trace raw tracepoints so that user can trace
tracepoints which don't have traceevent wrappers. This new event is
always available if the fprobe_events is enabled (thus no kconfig),
because the fprobe_events depends on the trace-event and traceporint.
e.g.
# echo 't sched_overutilized_tp' >> dynamic_events
# echo 't 9p_client_req' >> dynamic_events
# cat dynamic_events
t:tracepoints/sched_overutilized_tp sched_overutilized_tp
t:tracepoints/_9p_client_req 9p_client_req
The event name is based on the tracepoint name, but if it is started
with digit character, an underscore '_' will be added.
NOTE: to avoid further confusion, this renames TPARG_FL_TPOINT to
TPARG_FL_TEVENT because this flag is used for eprobe (trace-event probe).
And reuse TPARG_FL_TPOINT for this raw tracepoint probe.
Link: https://lore.kernel.org/all/168507471874.913472.17214624519622959593.stgit@mhiramat.roam.corp.google.com/
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202305020453.afTJ3VVp-lkp@intel.com/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Pull tracing fixes from Steven Rostedt:
- Do not allow histogram values to have modifies. They can cause a NULL
pointer dereference if they do.
- Warn if hist_field_name() is passed a NULL. Prevent the NULL pointer
dereference mentioned above.
- Fix invalid address look up race in lookup_rec()
- Define ftrace_stub_graph conditionally to prevent linker errors
- Always check if RCU is watching at all tracepoint locations
* tag 'trace-v6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing: Make tracepoint lockdep check actually test something
ftrace,kcfi: Define ftrace_stub_graph conditionally
ftrace: Fix invalid address access in lookup_rec() when index is 0
tracing: Check field value in hist_field_name()
tracing: Do not let histogram values have some modifiers
A while ago where the trace events had the following:
rcu_read_lock_sched_notrace();
rcu_dereference_sched(...);
rcu_read_unlock_sched_notrace();
If the tracepoint is enabled, it could trigger RCU issues if called in
the wrong place. And this warning was only triggered if lockdep was
enabled. If the tracepoint was never enabled with lockdep, the bug would
not be caught. To handle this, the above sequence was done when lockdep
was enabled regardless if the tracepoint was enabled or not (although the
always enabled code really didn't do anything, it would still trigger a
warning).
But a lot has changed since that lockdep code was added. One is, that
sequence no longer triggers any warning. Another is, the tracepoint when
enabled doesn't even do that sequence anymore.
The main check we care about today is whether RCU is "watching" or not.
So if lockdep is enabled, always check if rcu_is_watching() which will
trigger a warning if it is not (tracepoints require RCU to be watching).
Note, that old sequence did add a bit of overhead when lockdep was enabled,
and with the latest kernel updates, would cause the system to slow down
enough to trigger kernel "stalled" warnings.
Link: http://lore.kernel.org/lkml/20140806181801.GA4605@redhat.com
Link: http://lore.kernel.org/lkml/20140807175204.C257CAC5@viggo.jf.intel.com
Link: https://lore.kernel.org/lkml/20230307184645.521db5c9@gandalf.local.home/
Link: https://lore.kernel.org/linux-trace-kernel/20230310172856.77406446@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Fixes: e6753f23d9 ("tracepoint: Make rcuidle tracepoint callers use SRCU")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Pull tracing updates from Steven Rostedt:
- Add function names as a way to filter function addresses
- Add sample module to test ftrace ops and dynamic trampolines
- Allow stack traces to be passed from beginning event to end event for
synthetic events. This will allow seeing the stack trace of when a
task is scheduled out and recorded when it gets scheduled back in.
- Add trace event helper __get_buf() to use as a temporary buffer when
printing out trace event output.
- Add kernel command line to create trace instances on boot up.
- Add enabling of events to instances created at boot up.
- Add trace_array_puts() to write into instances.
- Allow boot instances to take a snapshot at the end of boot up.
- Allow live patch modules to include trace events
- Minor fixes and clean ups
* tag 'trace-v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (31 commits)
tracing: Remove unnecessary NULL assignment
tracepoint: Allow livepatch module add trace event
tracing: Always use canonical ftrace path
tracing/histogram: Fix stacktrace histogram Documententation
tracing/histogram: Fix stacktrace key
tracing/histogram: Fix a few problems with stacktrace variable printing
tracing: Add BUILD_BUG() to make sure stacktrace fits in strings
tracing/histogram: Don't use strlen to find length of stacktrace variables
tracing: Allow boot instances to have snapshot buffers
tracing: Add trace_array_puts() to write into instance
tracing: Add enabling of events to boot instances
tracing: Add creation of instances at boot command line
tracing: Fix trace_event_raw_event_synth() if else statement
samples: ftrace: Make some global variables static
ftrace: sample: avoid open-coded 64-bit division
samples: ftrace: Include the nospec-branch.h only for x86
tracing: Acquire buffer from temparary trace sequence
tracing/histogram: Wrap remaining shell snippets in code blocks
tracing/osnoise: No need for schedule_hrtimeout range
bpf/tracing: Use stage6 of tracing to not duplicate macros
...
The canonical location for the tracefs filesystem is at /sys/kernel/tracing.
But, from Documentation/trace/ftrace.rst:
Before 4.1, all ftrace tracing control files were within the debugfs
file system, which is typically located at /sys/kernel/debug/tracing.
For backward compatibility, when mounting the debugfs file system,
the tracefs file system will be automatically mounted at:
/sys/kernel/debug/tracing
Many comments and Kconfig help messages in the tracing code still refer
to this older debugfs path, so let's update them to avoid confusion.
Link: https://lore.kernel.org/linux-trace-kernel/20230215223350.2658616-2-zwisler@google.com
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com>
Signed-off-by: Ross Zwisler <zwisler@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Pull tracing updates from Steven Rostedt:
- Runtime verification infrastructure
This is the biggest change here. It introduces the runtime
verification that is necessary for running Linux on safety critical
systems.
It allows for deterministic automata models to be inserted into the
kernel that will attach to tracepoints, where the information on
these tracepoints will move the model from state to state.
If a state is encountered that does not belong to the model, it will
then activate a given reactor, that could just inform the user or
even panic the kernel (for which safety critical systems will detect
and can recover from).
- Two monitor models are also added: Wakeup In Preemptive (WIP - not to
be confused with "work in progress"), and Wakeup While Not Running
(WWNR).
- Added __vstring() helper to the TRACE_EVENT() macro to replace
several vsnprintf() usages that were all doing it wrong.
- eprobes now can have their event autogenerated when the event name is
left off.
- The rest is various cleanups and fixes.
* tag 'trace-v6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (50 commits)
rv: Unlock on error path in rv_unregister_reactor()
tracing: Use alignof__(struct {type b;}) instead of offsetof()
tracing/eprobe: Show syntax error logs in error_log file
scripts/tracing: Fix typo 'the the' in comment
tracepoints: It is CONFIG_TRACEPOINTS not CONFIG_TRACEPOINT
tracing: Use free_trace_buffer() in allocate_trace_buffers()
tracing: Use a struct alignof to determine trace event field alignment
rv/reactor: Add the panic reactor
rv/reactor: Add the printk reactor
rv/monitor: Add the wwnr monitor
rv/monitor: Add the wip monitor
rv/monitor: Add the wip monitor skeleton created by dot2k
Documentation/rv: Add deterministic automata instrumentation documentation
Documentation/rv: Add deterministic automata monitor synthesis documentation
tools/rv: Add dot2k
Documentation/rv: Add deterministic automaton documentation
tools/rv: Add dot2c
Documentation/rv: Add a basic documentation
rv/include: Add instrumentation helper functions
rv/include: Add deterministic automata monitor definition via C macros
...
All internal use cases for tracepoint_probe_register() is set to not ever
be called with the same function and data. If it is, it is considered a
bug, as that means the accounting of handling tracepoints is corrupted.
If the function and data for a tracepoint is already registered when
tracepoint_probe_register() is called, it will call WARN_ON_ONCE() and
return with EEXISTS.
The BPF system call can end up calling tracepoint_probe_register() with
the same data, which now means that this can trigger the warning because
of a user space process. As WARN_ON_ONCE() should not be called because
user space called a system call with bad data, there needs to be a way to
register a tracepoint without triggering a warning.
Enter tracepoint_probe_register_may_exist(), which can be called, but will
not cause a WARN_ON() if the probe already exists. It will still error out
with EEXIST, which will then be sent to the user space that performed the
BPF system call.
This keeps the previous testing for issues with other users of the
tracepoint code, while letting BPF call it with duplicated data and not
warn about it.
Link: https://lore.kernel.org/lkml/20210626135845.4080-1-penguin-kernel@I-love.SAKURA.ne.jp/
Link: https://syzkaller.appspot.com/bug?id=41f4318cf01762389f4d1c1c459da4f542fe5153
Cc: stable@vger.kernel.org
Fixes: c4f6699dfc ("bpf: introduce BPF_RAW_TRACEPOINT")
Reported-by: syzbot <syzbot+721aa903751db87aa244@syzkaller.appspotmail.com>
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Tested-by: syzbot+721aa903751db87aa244@syzkaller.appspotmail.com
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
With static calls, a tracepoint can call the callback directly if there is
only one callback registered to that tracepoint. When there is more than
one, the static call will call the tracepoint's "iterator" function, which
needs to reload the tracepoint's "funcs" array again, as it could have
changed since the first time it was loaded.
But an arch without static calls is punished by having to load the
tracepoint's "funcs" array twice. Once in the DO_TRACE macro, and once
again in the iterator macro.
For archs without static calls, there's no reason to load the array macro
in the first place, since the iterator function will do it anyway.
Change the __DO_TRACE_CALL() macro to do the load and call of the
tracepoints funcs array only for architectures with static calls, and just
call the iterator function directly for architectures without static calls.
Link: https://lkml.kernel.org/r/20210208201050.909329787@goodmis.org
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
While working on a clean up that would restructure the difference between
architectures that have static calls vs those that do not, I was stumbling
over the "data_args" parameter that includes "__data" in the arguments. The
issue was that one version didn't even need it, while the other one did.
Instead of injecting a "__data = NULL;" into the macro for the unneeded
version, just remove it completely.
The original idea behind data_args is that there may be a case of a
tracepoint with no arguments. But this is considered bad practice, and all
tracepoints should pass something to that location (that's what tracepoints
were created for).
Link: https://lkml.kernel.org/r/20210208201050.768074128@goodmis.org
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
When executing a tracepoint, the tracepoint's func is dereferenced twice -
in __DO_TRACE() (where the returned pointer is checked) and later on in
__traceiter_##_name where the returned pointer is dereferenced without
checking which leads to races against tracepoint_removal_sync() and
crashes.
This adds a check before referencing the pointer in tracepoint_ptr_deref.
Link: https://lkml.kernel.org/r/20210202072326.120557-1-aik@ozlabs.ru
Cc: stable@vger.kernel.org
Fixes: d25e37d89d ("tracepoint: Optimize using static_call()")
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Currently the tracepoint site will iterate a vector and issue indirect
calls to however many handlers are registered (ie. the vector is
long).
Using static_call() it is possible to optimize this for the common
case of only having a single handler registered. In this case the
static_call() can directly call this handler. Otherwise, if the vector
is longer than 1, call a function that iterates the whole vector like
the current code.
[peterz: updated to new interface]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20200818135805.279421092@infradead.org
__tracepoint_string's have their string data stored in .rodata, and an
address to that data stored in the "__tracepoint_str" section. Functions
that refer to those strings refer to the symbol of the address. Compiler
optimization can replace those address references with references
directly to the string data. If the address doesn't appear to have other
uses, then it appears dead to the compiler and is removed. This can
break the /tracing/printk_formats sysfs node which iterates the
addresses stored in the "__tracepoint_str" section.
Like other strings stored in custom sections in this header, mark these
__used to inform the compiler that there are other non-obvious users of
the address, so they should still be emitted.
Link: https://lkml.kernel.org/r/20200730224555.2142154-2-ndesaulniers@google.com
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc: stable@vger.kernel.org
Fixes: 102c9323c3 ("tracing: Add __tracepoint_string() to export string pointers")
Reported-by: Tim Murray <timmurray@google.com>
Reported-by: Simon MacMullen <simonmacm@google.com>
Suggested-by: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Pull RCU changes from Paul E. McKenney:
- Convert RCU's BUG_ON() and similar calls to WARN_ON() and similar.
- Replace calls of RCU-bh and RCU-sched update-side functions
to their vanilla RCU counterparts. This series is a step
towards complete removal of the RCU-bh and RCU-sched update-side
functions.
( Note that some of these conversions are going upstream via their
respective maintainers. )
- Documentation updates, including a number of flavor-consolidation
updates from Joel Fernandes.
- Miscellaneous fixes.
- Automate generation of the initrd filesystem used for
rcutorture testing.
- Convert spin_is_locked() assertions to instead use lockdep.
( Note that some of these conversions are going upstream via their
respective maintainers. )
- SRCU updates, especially including a fix from Dennis Krein
for a bag-on-head-class bug.
- RCU torture-test updates.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
After enabling KVM event tracing, almost all of trace_kvm_exit()'s
printk shows
"kvm_exit: IRQ: ..."
even if the actual exception_type is NOT IRQ. More specifically,
trace_kvm_exit() is defined in virt/kvm/arm/trace.h by TRACE_EVENT.
This slight problem may have existed after commit e6753f23d9
("tracepoint: Make rcuidle tracepoint callers use SRCU"). There are
two variables in trace_kvm_exit() and __DO_TRACE() which have the
same name, *idx*. Thus the actual value of *idx* will be overwritten
when tracing. Fix it by adding a simple prefix.
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Wang Haibin <wanghaibin.wang@huawei.com>
Cc: linux-trace-devel@vger.kernel.org
Cc: stable@vger.kernel.org
Fixes: e6753f23d9 ("tracepoint: Make rcuidle tracepoint callers use SRCU")
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Now that synchronize_rcu() waits for preempt-disable regions of code
as well as RCU read-side critical sections, synchronize_sched() can
be replaced by synchronize_rcu(). Similarly, call_rcu_sched() can be
replaced by call_rcu(). This commit therefore makes these changes.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: <linux-kernel@vger.kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
commit 46e0c9be20 ("kernel: tracepoints: add support for relative
references") changes the layout of the __tracepoint_ptrs section on
architectures supporting relative references. However, it does so
without turning struct tracepoint * const into const int elsewhere in
the tracepoint code, which has the following side-effect:
Setting mod->num_tracepoints is done in by module.c:
mod->tracepoints_ptrs = section_objs(info, "__tracepoints_ptrs",
sizeof(*mod->tracepoints_ptrs),
&mod->num_tracepoints);
Basically, since sizeof(*mod->tracepoints_ptrs) is a pointer size
(rather than sizeof(int)), num_tracepoints is erroneously set to half the
size it should be on 64-bit arch. So a module with an odd number of
tracepoints misses the last tracepoint due to effect of integer
division.
So in the module going notifier:
for_each_tracepoint_range(mod->tracepoints_ptrs,
mod->tracepoints_ptrs + mod->num_tracepoints,
tp_module_going_check_quiescent, NULL);
the expression (mod->tracepoints_ptrs + mod->num_tracepoints) actually
evaluates to something within the bounds of the array, but miss the
last tracepoint if the number of tracepoints is odd on 64-bit arch.
Fix this by introducing a new typedef: tracepoint_ptr_t, which
is either "const int" on architectures that have PREL32 relocations,
or "struct tracepoint * const" on architectures that does not have
this feature.
Also provide a new tracepoint_ptr_defer() static inline to
encapsulate deferencing this type rather than duplicate code and
ugly idefs within the for_each_tracepoint_range() implementation.
This issue appears in 4.19-rc kernels, and should ideally be fixed
before the end of the rc cycle.
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Jessica Yu <jeyu@kernel.org>
Link: http://lkml.kernel.org/r/20181013191050.22389-1-mathieu.desnoyers@efficios.com
Link: http://lkml.kernel.org/r/20180704083651.24360-7-ard.biesheuvel@linaro.org
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morris <james.morris@microsoft.com>
Cc: James Morris <jmorris@namei.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Nicolas Pitre <nico@linaro.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Thomas Garnier <thgarnie@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Borislav reported the following splat:
=============================
WARNING: suspicious RCU usage
4.19.0-rc1+ #1 Not tainted
-----------------------------
./include/linux/rcupdate.h:631 rcu_read_lock() used illegally while idle!
other info that might help us debug this:
RCU used illegally from idle CPU!
rcu_scheduler_active = 2, debug_locks = 1
RCU used illegally from extended quiescent state!
1 lock held by swapper/0/0:
#0: 000000004557ee0e (rcu_read_lock){....}, at: perf_event_output_forward+0x0/0x130
stack backtrace:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.19.0-rc1+ #1
Hardware name: LENOVO 2320CTO/2320CTO, BIOS G2ET86WW (2.06 ) 11/13/2012
Call Trace:
dump_stack+0x85/0xcb
perf_event_output_forward+0xf6/0x130
__perf_event_overflow+0x52/0xe0
perf_swevent_overflow+0x91/0xb0
perf_tp_event+0x11a/0x350
? find_held_lock+0x2d/0x90
? __lock_acquire+0x2ce/0x1350
? __lock_acquire+0x2ce/0x1350
? retint_kernel+0x2d/0x2d
? find_held_lock+0x2d/0x90
? tick_nohz_get_sleep_length+0x83/0xb0
? perf_trace_cpu+0xbb/0xd0
? perf_trace_buf_alloc+0x5a/0xa0
perf_trace_cpu+0xbb/0xd0
cpuidle_enter_state+0x185/0x340
do_idle+0x1eb/0x260
cpu_startup_entry+0x5f/0x70
start_kernel+0x49b/0x4a6
secondary_startup_64+0xa4/0xb0
This is due to the tracepoints moving to SRCU usage which does not require
RCU to be "watching". But perf uses these tracepoints with RCU and expects
it to be. Hence, we still need to add in the rcu_irq_enter/exit_irqson()
calls for "rcuidle" tracepoints. This is a temporary fix until we have SRCU
working in NMI context, and then perf can be converted to use that instead
of normal RCU.
Link: http://lkml.kernel.org/r/20180904162611.6a120068@gandalf.local.home
Cc: x86-ml <x86@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Reported-by: Borislav Petkov <bp@alien8.de>
Tested-by: Borislav Petkov <bp@alien8.de>
Reviewed-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Fixes: e6753f23d9 ("tracepoint: Make rcuidle tracepoint callers use SRCU")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Linus Torvalds