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>
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>
To avoid the need for relocating absolute references to tracepoint
structures at boot time when running relocatable kernels (which may
take a disproportionate amount of space), add the option to emit
these tables as relative references instead.
Link: http://lkml.kernel.org/r/20180704083651.24360-7-ard.biesheuvel@linaro.org
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: 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: Jessica Yu <jeyu@kernel.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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In recent tests with IRQ on/off tracepoints, a large performance
overhead ~10% is noticed when running hackbench. This is root caused to
calls to rcu_irq_enter_irqson and rcu_irq_exit_irqson from the
tracepoint code. Following a long discussion on the list [1] about this,
we concluded that srcu is a better alternative for use during rcu idle.
Although it does involve extra barriers, its lighter than the sched-rcu
version which has to do additional RCU calls to notify RCU idle about
entry into RCU sections.
In this patch, we change the underlying implementation of the
trace_*_rcuidle API to use SRCU. This has shown to improve performance
alot for the high frequency irq enable/disable tracepoints.
Test: Tested idle and preempt/irq tracepoints.
Here are some performance numbers:
With a run of the following 30 times on a single core x86 Qemu instance
with 1GB memory:
hackbench -g 4 -f 2 -l 3000
Completion times in seconds. CONFIG_PROVE_LOCKING=y.
No patches (without this series)
Mean: 3.048
Median: 3.025
Std Dev: 0.064
With Lockdep using irq tracepoints with RCU implementation:
Mean: 3.451 (-11.66 %)
Median: 3.447 (-12.22%)
Std Dev: 0.049
With Lockdep using irq tracepoints with SRCU implementation (this series):
Mean: 3.020 (I would consider the improvement against the "without
this series" case as just noise).
Median: 3.013
Std Dev: 0.033
[1] https://patchwork.kernel.org/patch/10344297/
[remove rcu_read_lock_sched_notrace as its the equivalent of
preempt_disable_notrace and is unnecessary to call in tracepoint code]
Link: http://lkml.kernel.org/r/20180730222423.196630-3-joel@joelfernandes.org
Cleaned-up-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
[ Simplified WARN_ON_ONCE() ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
The script:
./scripts/documentation-file-ref-check --fix
Gives multiple hints for broken references on some files.
Manually use the one that applies for some files.
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: James Morris <james.morris@microsoft.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Now that the irq path uses the rcu_nmi_{enter,exit}() algorithm,
rcu_irq_enter() and rcu_irq_exit() may be used from any context. There is
thus no need for rcu_irq_enter_disabled() and for the checks using it.
This commit therefore eliminates rcu_irq_enter_disabled().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Perf has a problem that if sizeof() macros are used within TRACE_EVENT()
macro's they end up in userspace as "sizeof(kernel structure)" which
cannot properly be parsed. Add a macro which can forward this data
through the eval_map for userspace utilization.
Link: http://lkml.kernel.org/r/20170531215653.3240-10-jeremy.linton@arm.com
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Each enum is loaded into the trace_enum_map, as we
are now using this for more than enums rename it.
Link: http://lkml.kernel.org/r/20170531215653.3240-3-jeremy.linton@arm.com
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Stack tracing discovered that there's a small location inside the RCU
infrastructure where calling rcu_irq_enter() does not work. As trace events
use rcu_irq_enter() it must make sure that it is functionable. A check
against rcu_irq_enter_disabled() is added with a WARN_ON_ONCE() as no trace
event should ever be used in that part of RCU. If the warning is triggered,
then the trace event is ignored.
Restructure the __DO_TRACE() a bit to get rid of the prercu and postrcu,
and just have an rcucheck that does the work from within the _DO_TRACE()
macro. gcc optimization will compile out the rcucheck=0 case.
Link: http://lkml.kernel.org/r/20170405093207.404f8deb@gandalf.local.home
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Some tracepoints have a registration function that gets enabled when the
tracepoint is enabled. There may be cases that the registraction function
must fail (for example, can't allocate enough memory). In this case, the
tracepoint should also fail to register, otherwise the user would not know
why the tracepoint is not working.
Cc: David Howells <dhowells@redhat.com>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Anton Blanchard <anton@samba.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Commit f37755490f ("tracepoints: Do not trace when cpu is offline") added
a check to make sure that tracepoints only get called when the cpu is
online, as it uses rcu_read_lock_sched() for protection.
Commit 3a630178fd ("tracing: generate RCU warnings even when tracepoints
are disabled") added lockdep checks (including rcu checks) for events that
are not enabled to catch possible RCU issues that would only be triggered if
a trace event was enabled. Commit f37755490f only stopped the warnings
when the trace event was enabled but did not prevent warnings if the trace
event was called when disabled.
To fix this, the cpu online check is moved to where the condition is added
to the trace event. This will place the cpu online check in all places that
it may be used now and in the future.
Cc: stable@vger.kernel.org # v3.18+
Fixes: f37755490f ("tracepoints: Do not trace when cpu is offline")
Fixes: 3a630178fd ("tracing: generate RCU warnings even when tracepoints are disabled")
Reported-by: Sudeep Holla <sudeep.holla@arm.com>
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The tracepoint infrastructure uses RCU sched protection to enable and
disable tracepoints safely. There are some instances where tracepoints are
used in infrastructure code (like kfree()) that get called after a CPU is
going offline, and perhaps when it is coming back online but hasn't been
registered yet.
This can probuce the following warning:
[ INFO: suspicious RCU usage. ]
4.4.0-00006-g0fe53e8-dirty #34 Tainted: G S
-------------------------------
include/trace/events/kmem.h:141 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
RCU used illegally from offline CPU! rcu_scheduler_active = 1, debug_locks = 1
no locks held by swapper/8/0.
stack backtrace:
CPU: 8 PID: 0 Comm: swapper/8 Tainted: G S 4.4.0-00006-g0fe53e8-dirty #34
Call Trace:
[c0000005b76c78d0] [c0000000008b9540] .dump_stack+0x98/0xd4 (unreliable)
[c0000005b76c7950] [c00000000010c898] .lockdep_rcu_suspicious+0x108/0x170
[c0000005b76c79e0] [c00000000029adc0] .kfree+0x390/0x440
[c0000005b76c7a80] [c000000000055f74] .destroy_context+0x44/0x100
[c0000005b76c7b00] [c0000000000934a0] .__mmdrop+0x60/0x150
[c0000005b76c7b90] [c0000000000e3ff0] .idle_task_exit+0x130/0x140
[c0000005b76c7c20] [c000000000075804] .pseries_mach_cpu_die+0x64/0x310
[c0000005b76c7cd0] [c000000000043e7c] .cpu_die+0x3c/0x60
[c0000005b76c7d40] [c0000000000188d8] .arch_cpu_idle_dead+0x28/0x40
[c0000005b76c7db0] [c000000000101e6c] .cpu_startup_entry+0x50c/0x560
[c0000005b76c7ed0] [c000000000043bd8] .start_secondary+0x328/0x360
[c0000005b76c7f90] [c000000000008a6c] start_secondary_prolog+0x10/0x14
This warning is not a false positive either. RCU is not protecting code that
is being executed while the CPU is offline.
Instead of playing "whack-a-mole(TM)" and adding conditional statements to
the tracepoints we find that are used in this instance, simply add a
cpu_online() test to the tracepoint code where the tracepoint will be
ignored if the CPU is offline.
Use of raw_smp_processor_id() is fine, as there should never be a case where
the tracepoint code goes from running on a CPU that is online and suddenly
gets migrated to a CPU that is offline.
Link: http://lkml.kernel.org/r/1455387773-4245-1-git-send-email-kda@linux-powerpc.org
Reported-by: Denis Kirjanov <kda@linux-powerpc.org>
Fixes: 97e1c18e8d ("tracing: Kernel Tracepoints")
Cc: stable@vger.kernel.org # v2.6.28+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
minor fixes.
Here's what else is new:
o A new TRACE_EVENT_FN_COND macro, combining both _FN and _COND for
those that want both.
o New selftest to test the instance create and delete
o Better debug output when ftrace fails
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Merge tag 'trace-v4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
"Not much new with tracing for this release. Mostly just clean ups and
minor fixes.
Here's what else is new:
- A new TRACE_EVENT_FN_COND macro, combining both _FN and _COND for
those that want both.
- New selftest to test the instance create and delete
- Better debug output when ftrace fails"
* tag 'trace-v4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (24 commits)
ftrace: Fix the race between ftrace and insmod
ftrace: Add infrastructure for delayed enabling of module functions
x86: ftrace: Fix the comments for ftrace_modify_code_direct()
tracing: Fix comment to use tracing_on over tracing_enable
metag: ftrace: Fix the comments for ftrace_modify_code
sh: ftrace: Fix the comments for ftrace_modify_code()
ia64: ftrace: Fix the comments for ftrace_modify_code()
ftrace: Clean up ftrace_module_init() code
ftrace: Join functions ftrace_module_init() and ftrace_init_module()
tracing: Introduce TRACE_EVENT_FN_COND macro
tracing: Use seq_buf_used() in seq_buf_to_user() instead of len
bpf: Constify bpf_verifier_ops structure
ftrace: Have ftrace_ops_get_func() handle RCU and PER_CPU flags too
ftrace: Remove use of control list and ops
ftrace: Fix output of enabled_functions for showing tramp
ftrace: Fix a typo in comment
ftrace: Show all tramps registered to a record on ftrace_bug()
ftrace: Add variable ftrace_expected for archs to show expected code
ftrace: Add new type to distinguish what kind of ftrace_bug()
tracing: Update cond flag when enabling or disabling a trigger
...
Pull perf updates from Ingo Molnar:
"Kernel side changes:
- Intel Knights Landing support. (Harish Chegondi)
- Intel Broadwell-EP uncore PMU support. (Kan Liang)
- Core code improvements. (Peter Zijlstra.)
- Event filter, LBR and PEBS fixes. (Stephane Eranian)
- Enable cycles:pp on Intel Atom. (Stephane Eranian)
- Add cycles:ppp support for Skylake. (Andi Kleen)
- Various x86 NMI overhead optimizations. (Andi Kleen)
- Intel PT enhancements. (Takao Indoh)
- AMD cache events fix. (Vince Weaver)
Tons of tooling changes:
- Show random perf tool tips in the 'perf report' bottom line
(Namhyung Kim)
- perf report now defaults to --group if the perf.data file has
grouped events, try it with:
# perf record -e '{cycles,instructions}' -a sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 1.093 MB perf.data (1247 samples) ]
# perf report
# Samples: 1K of event 'anon group { cycles, instructions }'
# Event count (approx.): 1955219195
#
# Overhead Command Shared Object Symbol
2.86% 0.22% swapper [kernel.kallsyms] [k] intel_idle
1.05% 0.33% firefox libxul.so [.] js::SetObjectElement
1.05% 0.00% kworker/0:3 [kernel.kallsyms] [k] gen6_ring_get_seqno
0.88% 0.17% chrome chrome [.] 0x0000000000ee27ab
0.65% 0.86% firefox libxul.so [.] js::ValueToId<(js::AllowGC)1>
0.64% 0.23% JS Helper libxul.so [.] js::SplayTree<js::jit::LiveRange*, js::jit::LiveRange>::splay
0.62% 1.27% firefox libxul.so [.] js::GetIterator
0.61% 1.74% firefox libxul.so [.] js::NativeSetProperty
0.61% 0.31% firefox libxul.so [.] js::SetPropertyByDefining
- Introduce the 'perf stat record/report' workflow:
Generate perf.data files from 'perf stat', to tap into the
scripting capabilities perf has instead of defining a 'perf stat'
specific scripting support to calculate event ratios, etc.
Simple example:
$ perf stat record -e cycles usleep 1
Performance counter stats for 'usleep 1':
1,134,996 cycles
0.000670644 seconds time elapsed
$ perf stat report
Performance counter stats for '/home/acme/bin/perf stat record -e cycles usleep 1':
1,134,996 cycles
0.000670644 seconds time elapsed
$
It generates PERF_RECORD_ userspace records to store the details:
$ perf report -D | grep PERF_RECORD
0xf0 [0x28]: PERF_RECORD_THREAD_MAP nr: 1 thread: 27637
0x118 [0x12]: PERF_RECORD_CPU_MAP nr: 1 cpu: 65535
0x12a [0x40]: PERF_RECORD_STAT_CONFIG
0x16a [0x30]: PERF_RECORD_STAT
-1 -1 0x19a [0x40]: PERF_RECORD_MMAP -1/0: [0xffffffff81000000(0x1f000000) @ 0xffffffff81000000]: x [kernel.kallsyms]_text
0x1da [0x18]: PERF_RECORD_STAT_ROUND
[acme@ssdandy linux]$
An effort was made to make perf.data files generated like this to
not generate cryptic messages when processed by older tools.
The 'perf script' bits need rebasing, will go up later.
- Make command line options always available, even when they depend
on some feature being enabled, warning the user about use of such
options (Wang Nan)
- Support hw breakpoint events (mem:0xAddress) in the default output
mode in 'perf script' (Wang Nan)
- Fixes and improvements for supporting annotating ARM binaries,
support ARM call and jump instructions, more work needed to have
arch specific stuff separated into tools/perf/arch/*/annotate/
(Russell King)
- Add initial 'perf config' command, for now just with a --list
command to the contents of the configuration file in use and a
basic man page describing its format, commands for doing edits and
detailed documentation are being reviewed and proof-read. (Taeung
Song)
- Allows BPF scriptlets specify arguments to be fetched using DWARF
info, using a prologue generated at compile/build time (He Kuang,
Wang Nan)
- Allow attaching BPF scriptlets to module symbols (Wang Nan)
- Allow attaching BPF scriptlets to userspace code using uprobe (Wang
Nan)
- BPF programs now can specify 'perf probe' tunables via its section
name, separating key=val values using semicolons (Wang Nan)
Testing some of these new BPF features:
Use case: get callchains when receiving SSL packets, filter then in the
kernel, at arbitrary place.
# cat ssl.bpf.c
#define SEC(NAME) __attribute__((section(NAME), used))
struct pt_regs;
SEC("func=__inet_lookup_established hnum")
int func(struct pt_regs *ctx, int err, unsigned short port)
{
return err == 0 && port == 443;
}
char _license[] SEC("license") = "GPL";
int _version SEC("version") = LINUX_VERSION_CODE;
#
# perf record -a -g -e ssl.bpf.c
^C[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.787 MB perf.data (3 samples) ]
# perf script | head -30
swapper 0 [000] 58783.268118: perf_bpf_probe:func: (ffffffff816a0f60) hnum=0x1bb
8a0f61 __inet_lookup_established (/lib/modules/4.3.0+/build/vmlinux)
896def ip_rcv_finish (/lib/modules/4.3.0+/build/vmlinux)
8976c2 ip_rcv (/lib/modules/4.3.0+/build/vmlinux)
855eba __netif_receive_skb_core (/lib/modules/4.3.0+/build/vmlinux)
8565d8 __netif_receive_skb (/lib/modules/4.3.0+/build/vmlinux)
8572a8 process_backlog (/lib/modules/4.3.0+/build/vmlinux)
856b11 net_rx_action (/lib/modules/4.3.0+/build/vmlinux)
2a284b __do_softirq (/lib/modules/4.3.0+/build/vmlinux)
2a2ba3 irq_exit (/lib/modules/4.3.0+/build/vmlinux)
96b7a4 do_IRQ (/lib/modules/4.3.0+/build/vmlinux)
969807 ret_from_intr (/lib/modules/4.3.0+/build/vmlinux)
2dede5 cpu_startup_entry (/lib/modules/4.3.0+/build/vmlinux)
95d5bc rest_init (/lib/modules/4.3.0+/build/vmlinux)
1163ffa start_kernel ([kernel.vmlinux].init.text)
11634d7 x86_64_start_reservations ([kernel.vmlinux].init.text)
1163623 x86_64_start_kernel ([kernel.vmlinux].init.text)
qemu-system-x86 9178 [003] 58785.792417: perf_bpf_probe:func: (ffffffff816a0f60) hnum=0x1bb
8a0f61 __inet_lookup_established (/lib/modules/4.3.0+/build/vmlinux)
896def ip_rcv_finish (/lib/modules/4.3.0+/build/vmlinux)
8976c2 ip_rcv (/lib/modules/4.3.0+/build/vmlinux)
855eba __netif_receive_skb_core (/lib/modules/4.3.0+/build/vmlinux)
8565d8 __netif_receive_skb (/lib/modules/4.3.0+/build/vmlinux)
856660 netif_receive_skb_internal (/lib/modules/4.3.0+/build/vmlinux)
8566ec netif_receive_skb_sk (/lib/modules/4.3.0+/build/vmlinux)
430a br_handle_frame_finish ([bridge])
48bc br_handle_frame ([bridge])
855f44 __netif_receive_skb_core (/lib/modules/4.3.0+/build/vmlinux)
8565d8 __netif_receive_skb (/lib/modules/4.3.0+/build/vmlinux)
#
- Use 'perf probe' various options to list functions, see what
variables can be collected at any given point, experiment first
collecting without a filter, then filter, use it together with
'perf trace', 'perf top', with or without callchains, if it
explodes, please tell us!
- Introduce a new callchain mode: "folded", that will list per line
representations of all callchains for a give histogram entry,
facilitating 'perf report' output processing by other tools, such
as Brendan Gregg's flamegraph tools (Namhyung Kim)
E.g:
# perf report | grep -v ^# | head
18.37% 0.00% swapper [kernel.kallsyms] [k] cpu_startup_entry
|
---cpu_startup_entry
|
|--12.07%--start_secondary
|
--6.30%--rest_init
start_kernel
x86_64_start_reservations
x86_64_start_kernel
#
Becomes, in "folded" mode:
# perf report -g folded | grep -v ^# | head -5
18.37% 0.00% swapper [kernel.kallsyms] [k] cpu_startup_entry
12.07% cpu_startup_entry;start_secondary
6.30% cpu_startup_entry;rest_init;start_kernel;x86_64_start_reservations;x86_64_start_kernel
16.90% 0.00% swapper [kernel.kallsyms] [k] call_cpuidle
11.23% call_cpuidle;cpu_startup_entry;start_secondary
5.67% call_cpuidle;cpu_startup_entry;rest_init;start_kernel;x86_64_start_reservations;x86_64_start_kernel
16.90% 0.00% swapper [kernel.kallsyms] [k] cpuidle_enter
11.23% cpuidle_enter;call_cpuidle;cpu_startup_entry;start_secondary
5.67% cpuidle_enter;call_cpuidle;cpu_startup_entry;rest_init;start_kernel;x86_64_start_reservations;x86_64_start_kernel
15.12% 0.00% swapper [kernel.kallsyms] [k] cpuidle_enter_state
#
The user can also select one of "count", "period" or "percent" as
the first column.
... and lots of infrastructure enhancements, plus fixes and other
changes, features I failed to list - see the shortlog and the git log
for details"
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (271 commits)
perf evlist: Add --trace-fields option to show trace fields
perf record: Store data mmaps for dwarf unwind
perf libdw: Check for mmaps also in MAP__VARIABLE tree
perf unwind: Check for mmaps also in MAP__VARIABLE tree
perf unwind: Use find_map function in access_dso_mem
perf evlist: Remove perf_evlist__(enable|disable)_event functions
perf evlist: Make perf_evlist__open() open evsels with their cpus and threads (like perf record does)
perf report: Show random usage tip on the help line
perf hists: Export a couple of hist functions
perf diff: Use perf_hpp__register_sort_field interface
perf tools: Add overhead/overhead_children keys defaults via string
perf tools: Remove list entry from struct sort_entry
perf tools: Include all tools/lib directory for tags/cscope/TAGS targets
perf script: Align event name properly
perf tools: Add missing headers in perf's MANIFEST
perf tools: Do not show trace command if it's not compiled in
perf report: Change default to use event group view
perf top: Decay periods in callchains
tools lib: Move bitmap.[ch] from tools/perf/ to tools/{lib,include}/
tools lib: Sync tools/lib/find_bit.c with the kernel
...
TRACE_EVENT_FN can't be used in some circumstances
like invoking trace functions from offlined CPU due
to RCU usage.
This patch adds the TRACE_EVENT_FN_COND macro
to make such trace points conditional.
Link: http://lkml.kernel.org/r/1450124286-4822-1-git-send-email-kda@linux-powerpc.org
Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit replaces a local_irq_save()/local_irq_restore() pair with
a lockdep assertion that interrupts are already disabled. This should
remove the corresponding overhead from the interrupt entry/exit fastpaths.
This change was inspired by the fact that Iftekhar Ahmed's mutation
testing showed that removing rcu_irq_enter()'s call to local_ird_restore()
had no effect, which might indicate that interrupts were always enabled
anyway.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Steven recommended open coding access to tracepoint->key to add
trace points to headers. Unfortunately this is difficult for some
headers (such as x86 asm/msr.h) because including tracepoint.h
includes so many other headers that it causes include loops.
The main problem is the include of linux/rcupdate.h, which
pulls in a lot of other headers. The rcu header is only needed
when actually defining trace points.
Move the struct tracepoint into a separate tracepoint-defs.h
header that can be included without pulling in all of RCU.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/1449018060-1742-2-git-send-email-andi@firstfloor.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The documentation on top of __DECLARE_TRACE() does not match its
implementation since the condition check has been added to the
RCU lockdep checks. Update the documentation to match its
implementation.
Link: http://lkml.kernel.org/r/1446504164-21563-1-git-send-email-mathieu.desnoyers@efficios.com
CC: Dave Hansen <dave@sr71.net>
Fixes: a05d59a567 "tracing: Add condition check to RCU lockdep checks"
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
In order to guarantee that a probe will be called before other probes that
are attached to a tracepoint, there needs to be a mechanism to provide
priority of one probe over the others.
Adding a prio field to the struct tracepoint_func, which lets the probes be
sorted by the priority set in the structure. If no priority is specified,
then a priority of 10 is given (this is a macro, and perhaps may be changed
in the future).
Now probes may be added to affect other probes that are attached to a
tracepoint with a guaranteed order.
One use case would be to allow tracing of tracepoints be able to filter by
pid. A special (higher priority probe) may be added to the sched_switch
tracepoint and set the necessary flags of the other tracepoints to notify
them if they should be traced or not. In case a tracepoint is enabled at the
sched_switch tracepoint too, the order of the two are not random.
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Allow a trace events header file to disable compilation of its
trace events by defining the preprocessor macro NOTRACE.
This could be done, for example, according to a Kconfig option.
Link: http://lkml.kernel.org/r/1438432079-11704-3-git-send-email-tal.shorer@gmail.com
Signed-off-by: Tal Shorer <tal.shorer@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Several tracepoints use the helper functions __print_symbolic() or
__print_flags() and pass in enums that do the mapping between the
binary data stored and the value to print. This works well for reading
the ASCII trace files, but when the data is read via userspace tools
such as perf and trace-cmd, the conversion of the binary value to a
human string format is lost if an enum is used, as userspace does not
have access to what the ENUM is.
For example, the tracepoint trace_tlb_flush() has:
__print_symbolic(REC->reason,
{ TLB_FLUSH_ON_TASK_SWITCH, "flush on task switch" },
{ TLB_REMOTE_SHOOTDOWN, "remote shootdown" },
{ TLB_LOCAL_SHOOTDOWN, "local shootdown" },
{ TLB_LOCAL_MM_SHOOTDOWN, "local mm shootdown" })
Which maps the enum values to the strings they represent. But perf and
trace-cmd do no know what value TLB_LOCAL_MM_SHOOTDOWN is, and would
not be able to map it.
With TRACE_DEFINE_ENUM(), developers can place these in the event header
files and ftrace will convert the enums to their values:
By adding:
TRACE_DEFINE_ENUM(TLB_FLUSH_ON_TASK_SWITCH);
TRACE_DEFINE_ENUM(TLB_REMOTE_SHOOTDOWN);
TRACE_DEFINE_ENUM(TLB_LOCAL_SHOOTDOWN);
TRACE_DEFINE_ENUM(TLB_LOCAL_MM_SHOOTDOWN);
$ cat /sys/kernel/debug/tracing/events/tlb/tlb_flush/format
[...]
__print_symbolic(REC->reason,
{ 0, "flush on task switch" },
{ 1, "remote shootdown" },
{ 2, "local shootdown" },
{ 3, "local mm shootdown" })
The above is what userspace expects to see, and tools do not need to
be modified to parse them.
Link: http://lkml.kernel.org/r/20150403013802.220157513@goodmis.org
Cc: Guilherme Cox <cox@computer.org>
Cc: Tony Luck <tony.luck@gmail.com>
Cc: Xie XiuQi <xiexiuqi@huawei.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The trace_tlb_flush() tracepoint can be called when a CPU is going offline.
When a CPU is offline, RCU is no longer watching that CPU and since the
tracepoint is protected by RCU, it must not be called. To prevent the
tlb_flush tracepoint from being called when the CPU is offline, it was
converted to a TRACE_EVENT_CONDITION where the condition checks if the
CPU is online before calling the tracepoint.
Unfortunately, this was not enough to stop lockdep from complaining about
it. Even though the RCU protected code of the tracepoint will never be
called, the condition is hidden within the tracepoint, and even though the
condition prevents RCU code from being called, the lockdep checks are
outside the tracepoint (this is to test tracepoints even when they are not
enabled).
Even though tracepoints should be checked to be RCU safe when they are not
enabled, the condition should still be considered when checking RCU.
Link: http://lkml.kernel.org/r/CA+icZUUGiGDoL5NU8RuxKzFjoLjEKRtUWx=JB8B9a0EQv-eGzQ@mail.gmail.com
Fixes: 3a630178fd "tracing: generate RCU warnings even when tracepoints are disabled"
Cc: stable@vger.kernel.org # 3.18+
Acked-by: Dave Hansen <dave@sr71.net>
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Dave Jones reported seeing a bug from one of my TLB tracepoints:
http://lkml.kernel.org/r/20140806181801.GA4605@redhat.com
I've been running these patches for months and never saw this.
But, a big chunk of my testing, especially with all the debugging
enabled, was in a vm where intel_idle doesn't work. On the
systems where I was using intel_idle, I never had lockdep enabled
and this tracepoint on at the same time.
This patch ensures that whenever we have lockdep available, we do
_some_ RCU activity at the site of the tracepoint, despite
whether the tracepoint's condition matches or even if the
tracepoint itself is completely disabled. This is a bit of a
hack, but it is pretty self-contained.
I confirmed that with this patch plus lockdep I get the same
splat as Dave Jones did, but without enabling the tracepoint
explicitly.
Link: http://lkml.kernel.org/p/20140807175204.C257CAC5@viggo.jf.intel.com
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Dave Jones <davej@redhat.com>,
Cc: paulmck@linux.vnet.ibm.com
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When CONFIG_TRACING is not enabled, there's no reason to save the trace
strings either by the linker or as a static variable that can be
referenced later. Simply pass back the string that is given to
tracepoint_string().
Had to move the define to include/linux/tracepoint.h so that it is still
visible when CONFIG_TRACING is not set.
Link: http://lkml.kernel.org/p/1406318733-26754-2-git-send-email-nicolas.pitre@linaro.org
Suggested-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
There are some code paths in the kernel that need to do some preparations
before it calls a tracepoint. As that code is worthless overhead when
the tracepoint is not enabled, it would be prudent to have that code
only run when the tracepoint is active. To accomplish this, all tracepoints
now get a static inline function called "trace_<tracepoint-name>_enabled()"
which returns true when the tracepoint is enabled and false otherwise.
As an added bonus, that function uses the static_key of the tracepoint
such that no branch is needed.
if (trace_mytracepoint_enabled()) {
arg = process_tp_arg();
trace_mytracepoint(arg);
}
Will keep the "process_tp_arg()" (which may be expensive to run) from
being executed when the tracepoint isn't enabled.
It's best to encapsulate the tracepoint itself in the if statement
just to keep races. For example, if you had:
if (trace_mytracepoint_enabled())
arg = process_tp_arg();
trace_mytracepoint(arg);
There's a chance that the tracepoint could be enabled just after the
if statement, and arg will be undefined when calling the tracepoint.
Link: http://lkml.kernel.org/r/20140506094407.507b6435@gandalf.local.home
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Fix the following sparse warnings:
CHECK kernel/tracepoint.c
kernel/tracepoint.c:184:18: warning: incorrect type in assignment (different address spaces)
kernel/tracepoint.c:184:18: expected struct tracepoint_func *tp_funcs
kernel/tracepoint.c:184:18: got struct tracepoint_func [noderef] <asn:4>*funcs
kernel/tracepoint.c:216:18: warning: incorrect type in assignment (different address spaces)
kernel/tracepoint.c:216:18: expected struct tracepoint_func *tp_funcs
kernel/tracepoint.c:216:18: got struct tracepoint_func [noderef] <asn:4>*funcs
kernel/tracepoint.c:392:24: error: return expression in void function
CC kernel/tracepoint.o
kernel/tracepoint.c: In function tracepoint_module_going:
kernel/tracepoint.c:491:6: warning: symbol 'syscall_regfunc' was not declared. Should it be static?
kernel/tracepoint.c:508:6: warning: symbol 'syscall_unregfunc' was not declared. Should it be static?
Link: http://lkml.kernel.org/r/1397049883-28692-1-git-send-email-mathieu.desnoyers@efficios.com
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Instead of copying the num_tracepoints and tracepoints_ptrs from
the module structure to the tp_mod structure, which only uses it to
find the module associated to tracepoints of modules that are coming
and going, simply copy the pointer to the module struct to the tracepoint
tp_module structure.
Also removed un-needed brackets around an if statement.
Link: http://lkml.kernel.org/r/20140408201705.4dad2c4a@gandalf.local.home
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Register/unregister tracepoint probes with struct tracepoint pointer
rather than tracepoint name.
This change, which vastly simplifies tracepoint.c, has been proposed by
Steven Rostedt. It also removes 8.8kB (mostly of text) to the vmlinux
size.
From this point on, the tracers need to pass a struct tracepoint pointer
to probe register/unregister. A probe can now only be connected to a
tracepoint that exists. Moreover, tracers are responsible for
unregistering the probe before the module containing its associated
tracepoint is unloaded.
text data bss dec hex filename
10443444 4282528 10391552 25117524 17f4354 vmlinux.orig
10434930 4282848 10391552 25109330 17f2352 vmlinux
Link: http://lkml.kernel.org/r/1396992381-23785-2-git-send-email-mathieu.desnoyers@efficios.com
CC: Ingo Molnar <mingo@kernel.org>
CC: Frederic Weisbecker <fweisbec@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Frank Ch. Eigler <fche@redhat.com>
CC: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
[ SDR - fixed return val in void func in tracepoint_module_going() ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
But there were a few features that were added.
Uprobes now work with event triggers and multi buffers.
Uprobes have support under ftrace and perf.
The big feature is that the function tracer can now be used within the
multi buffer instances. That is, you can now trace some functions
in one buffer, others in another buffer, all functions in a third buffer
and so on. They are basically agnostic from each other. This only
works for the function tracer and not for the function graph trace,
although you can have the function graph tracer running in the top level
buffer (or any tracer for that matter) and have different function tracing
going on in the sub buffers.
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Merge tag 'trace-3.15' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
"Most of the changes were largely clean ups, and some documentation.
But there were a few features that were added:
Uprobes now work with event triggers and multi buffers and have
support under ftrace and perf.
The big feature is that the function tracer can now be used within the
multi buffer instances. That is, you can now trace some functions in
one buffer, others in another buffer, all functions in a third buffer
and so on. They are basically agnostic from each other. This only
works for the function tracer and not for the function graph trace,
although you can have the function graph tracer running in the top
level buffer (or any tracer for that matter) and have different
function tracing going on in the sub buffers"
* tag 'trace-3.15' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (45 commits)
tracing: Add BUG_ON when stack end location is over written
tracepoint: Remove unused API functions
Revert "tracing: Move event storage for array from macro to standalone function"
ftrace: Constify ftrace_text_reserved
tracepoints: API doc update to tracepoint_probe_register() return value
tracepoints: API doc update to data argument
ftrace: Fix compilation warning about control_ops_free
ftrace/x86: BUG when ftrace recovery fails
ftrace: Warn on error when modifying ftrace function
ftrace: Remove freelist from struct dyn_ftrace
ftrace: Do not pass data to ftrace_dyn_arch_init
ftrace: Pass retval through return in ftrace_dyn_arch_init()
ftrace: Inline the code from ftrace_dyn_table_alloc()
ftrace: Cleanup of global variables ftrace_new_pgs and ftrace_update_cnt
tracing: Evaluate len expression only once in __dynamic_array macro
tracing: Correctly expand len expressions from __dynamic_array macro
tracing/module: Replace include of tracepoint.h with jump_label.h in module.h
tracing: Fix event header migrate.h to include tracepoint.h
tracing: Fix event header writeback.h to include tracepoint.h
tracing: Warn if a tracepoint is not set via debugfs
...
After the following commit:
commit b75ef8b44b
Author: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Wed Aug 10 15:18:39 2011 -0400
Tracepoint: Dissociate from module mutex
The following functions became unnecessary:
- tracepoint_probe_register_noupdate,
- tracepoint_probe_unregister_noupdate,
- tracepoint_probe_update_all.
In fact, none of the in-kernel tracers, nor LTTng, nor SystemTAP use
them. Remove those.
Moreover, the functions:
- tracepoint_iter_start,
- tracepoint_iter_next,
- tracepoint_iter_stop,
- tracepoint_iter_reset.
are unused by in-kernel tracers, LTTng and SystemTAP. Remove those too.
Link: http://lkml.kernel.org/r/1395379142-2118-2-git-send-email-mathieu.desnoyers@efficios.com
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
If a module fails to add its tracepoints due to module tainting, do not
create the module event infrastructure in the debugfs directory. As the events
will not work and worse yet, they will silently fail, making the user wonder
why the events they enable do not display anything.
Having a warning on module load and the events not visible to the users
will make the cause of the problem much clearer.
Link: http://lkml.kernel.org/r/20140227154923.265882695@goodmis.org
Fixes: 6d723736e4 "tracing/events: add support for modules to TRACE_EVENT"
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: stable@vger.kernel.org # 2.6.31+
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Binary was written as binay, probably by mistake. Fix it.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Vince's perf-trinity fuzzer found yet another 'interesting' problem.
When we sample the irq_work_exit tracepoint with period==1 (or
PERF_SAMPLE_PERIOD) and we add an fasync SIGNAL handler we create an
infinite event generation loop:
,-> <IPI>
| irq_work_exit() ->
| trace_irq_work_exit() ->
| ...
| __perf_event_overflow() -> (due to fasync)
| irq_work_queue() -> (irq_work_list must be empty)
'--------- arch_irq_work_raise()
Similar things can happen due to regular poll() wakeups if we exceed
the ring-buffer wakeup watermark, or have an event_limit.
To avoid this, dis-allow sampling this particular tracepoint.
In order to achieve this, create a special perf_perm function pointer
for each event and call this (when set) on trying to create a
tracepoint perf event.
[ roasted: use expr... to allow for ',' in your expression ]
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Tested-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20131114152304.GC5364@laptop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Each TRACE_EVENT() adds several helper functions. If two or more trace events
share the same structure and print format, they can also share most of these
helper functions and save a lot of space from duplicate code. This is why the
DECLARE_EVENT_CLASS() and DEFINE_EVENT() were created.
Some events require a trigger to be called at registering and unregistering of
the event and to do so they use TRACE_EVENT_FN().
If multiple events require a trigger, they currently have no choice but to use
TRACE_EVENT_FN() as there's no DEFINE_EVENT_FN() available. This unfortunately
causes a lot of wasted duplicate code created.
By adding a DEFINE_EVENT_FN(), these events can still use a
DECLARE_EVENT_CLASS() and then define their own triggers.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/51C3236C.8030508@hds.com
Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
__DECLARE_TRACE_RCU() currently creates an _rcuidle() tracepoint which
may safely be invoked from what RCU considers to be an idle CPU.
However, these _rcuidle() tracepoints may -not- be invoked from the
handler of an irq taken from idle, because rcu_idle_enter() zeroes
RCU's nesting-level counter, so that the rcu_irq_exit() returning to
idle will trigger a WARN_ON_ONCE().
This commit therefore substitutes rcu_irq_enter() for rcu_idle_exit()
and rcu_irq_exit() for rcu_idle_enter() in order to make the _rcuidle()
tracepoints usable from irq handlers as well as from process context.
Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Tracepoints declare a static inline trace_*_rcuidle variant of the trace
function, to support safely generating trace events from the idle loop.
Module code never actually uses that variant of trace functions, because
modules don't run code that needs tracing with RCU idled. However, the
declaration of those otherwise unused functions causes the module to
reference rcu_idle_exit and rcu_idle_enter, which RCU does not export to
modules.
To avoid this, don't generate trace_*_rcuidle functions for tracepoints
declared in module code.
Link: http://lkml.kernel.org/r/20120905062306.GA14756@leaf
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
So here's a boot tested patch on top of Jason's series that does
all the cleanups I talked about and turns jump labels into a
more intuitive to use facility. It should also address the
various misconceptions and confusions that surround jump labels.
Typical usage scenarios:
#include <linux/static_key.h>
struct static_key key = STATIC_KEY_INIT_TRUE;
if (static_key_false(&key))
do unlikely code
else
do likely code
Or:
if (static_key_true(&key))
do likely code
else
do unlikely code
The static key is modified via:
static_key_slow_inc(&key);
...
static_key_slow_dec(&key);
The 'slow' prefix makes it abundantly clear that this is an
expensive operation.
I've updated all in-kernel code to use this everywhere. Note
that I (intentionally) have not pushed through the rename
blindly through to the lowest levels: the actual jump-label
patching arch facility should be named like that, so we want to
decouple jump labels from the static-key facility a bit.
On non-jump-label enabled architectures static keys default to
likely()/unlikely() branches.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Jason Baron <jbaron@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: a.p.zijlstra@chello.nl
Cc: mathieu.desnoyers@efficios.com
Cc: davem@davemloft.net
Cc: ddaney.cavm@gmail.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20120222085809.GA26397@elte.hu
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Added is a new static inline function that lets *any* tracepoint be used
inside a rcu_idle_exit() section. And this also solves the problem where
the same tracepoint may be used inside a rcu_idle_exit() section as well
as outside of one.
I added a new tracepoint function with a "_rcuidle" extension. All
tracepoints can be used with either the normal "trace_foobar()"
function, or the "trace_foobar_rcuidle()" function when inside a
rcu_idle_exit() section.
All tracepoints defined by TRACE_EVENT() or any of the derivatives
will have a "_rcuidle()" function also defined. When a tracepoint is
used within an rcu_idle_exit() section, the "_rcuidle()" version must
be used. This denotes that the tracepoint is within rcu_idle_exit()
and it allows the rcu read locks within the tracepoint to still
be valid, as this version takes us out of rcu_idle_exit().
Another nice aspect about this patch is that "static inline"s are not
compiled into text when not used. So only the tracepoints that actually
use the _rcuidle() version will have them defined in the actual text
that is booted.
Link: http://lkml.kernel.org/r/1328563113.2200.39.camel@gandalf.stny.rr.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Copy the information needed from struct module into a local module list
held within tracepoint.c from within the module coming/going notifier.
This vastly simplifies locking of tracepoint registration /
unregistration, because we don't have to take the module mutex to
register and unregister tracepoints anymore. Steven Rostedt ran into
dependency problems related to modules mutex vs kprobes mutex vs ftrace
mutex vs tracepoint mutex that seems to be hard to fix without removing
this dependency between tracepoint and module mutex. (note: it should be
investigated whether kprobes could benefit of being dissociated from the
modules mutex too.)
This also fixes module handling of tracepoint list iterators, because it
was expecting the list to be sorted by pointer address. Given we have
control on our own list now, it's OK to sort this list which has
tracepoints as its only purpose. The reason why this sorting is required
is to handle the fact that seq files (and any read() operation from
user-space) cannot hold the tracepoint mutex across multiple calls, so
list entries may vanish between calls. With sorting, the tracepoint
iterator becomes usable even if the list don't contain the exact item
pointed to by the iterator anymore.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Jason Baron <jbaron@redhat.com>
CC: Ingo Molnar <mingo@elte.hu>
CC: Lai Jiangshan <laijs@cn.fujitsu.com>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Link: http://lkml.kernel.org/r/20110810191839.GC8525@Krystal
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Introduce:
static __always_inline bool static_branch(struct jump_label_key *key);
instead of the old JUMP_LABEL(key, label) macro.
In this way, jump labels become really easy to use:
Define:
struct jump_label_key jump_key;
Can be used as:
if (static_branch(&jump_key))
do unlikely code
enable/disale via:
jump_label_inc(&jump_key);
jump_label_dec(&jump_key);
that's it!
For the jump labels disabled case, the static_branch() becomes an
atomic_read(), and jump_label_inc()/dec() are simply atomic_inc(),
atomic_dec() operations. We show testing results for this change below.
Thanks to H. Peter Anvin for suggesting the 'static_branch()' construct.
Since we now require a 'struct jump_label_key *key', we can store a pointer into
the jump table addresses. In this way, we can enable/disable jump labels, in
basically constant time. This change allows us to completely remove the previous
hashtable scheme. Thanks to Peter Zijlstra for this re-write.
Testing:
I ran a series of 'tbench 20' runs 5 times (with reboots) for 3
configurations, where tracepoints were disabled.
jump label configured in
avg: 815.6
jump label *not* configured in (using atomic reads)
avg: 800.1
jump label *not* configured in (regular reads)
avg: 803.4
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20110316212947.GA8792@redhat.com>
Signed-off-by: Jason Baron <jbaron@redhat.com>
Suggested-by: H. Peter Anvin <hpa@linux.intel.com>
Tested-by: David Daney <ddaney@caviumnetworks.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Make the tracepoints more robust, making them solid enough to handle compiler
changes by not relying on anything based on compiler-specific behavior with
respect to structure alignment. Implement an approach proposed by David Miller:
use an array of const pointers to refer to the individual structures, and export
this pointer array through the linker script rather than the structures per se.
It will consume 32 extra bytes per tracepoint (24 for structure padding and 8
for the pointers), but are less likely to break due to compiler changes.
History:
commit 7e066fb8 tracepoints: add DECLARE_TRACE() and DEFINE_TRACE()
added the aligned(32) type and variable attribute to the tracepoint structures
to deal with gcc happily aligning statically defined structures on 32-byte
multiples.
One attempt was to use a 8-byte alignment for tracepoint structures by applying
both the variable and type attribute to tracepoint structures definitions and
declarations. It worked fine with gcc 4.5.1, but broke with gcc 4.4.4 and 4.4.5.
The reason is that the "aligned" attribute only specify the _minimum_ alignment
for a structure, leaving both the compiler and the linker free to align on
larger multiples. Because tracepoint.c expects the structures to be placed as an
array within each section, up-alignment cause NULL-pointer exceptions due to the
extra unexpected padding.
(this patch applies on top of -tip)
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: David S. Miller <davem@davemloft.net>
LKML-Reference: <20110126222622.GA10794@Krystal>
CC: Frederic Weisbecker <fweisbec@gmail.com>
CC: Ingo Molnar <mingo@elte.hu>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Peter Zijlstra <peterz@infradead.org>
CC: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
There are instances in the kernel that we only want to trace
a tracepoint when a certain condition is set. But we do not
want to test for that condition in the core kernel.
If we test for that condition before calling the tracepoin, then
we will be performing that test even when tracing is not enabled.
This is 99.99% of the time.
We currently can just filter out on that condition, but that happens
after we write to the trace buffer. We just wasted time writing to
the ring buffer for an event we never cared about.
This patch adds:
TRACE_EVENT_CONDITION() and DEFINE_EVENT_CONDITION()
These have a new TP_CONDITION() argument that comes right after
the TP_ARGS(). This condition can use the parameters of TP_ARGS()
in the TRACE_EVENT() to determine if the tracepoint should be traced
or not. The TP_CONDITION() will be placed in a if (cond) trace;
For example, for the tracepoint sched_wakeup, it is useless to
trace a wakeup event where the caller never actually wakes
anything up (where success == 0). So adding:
TP_CONDITION(success),
which uses the "success" parameter of the wakeup tracepoint
will have it only trace when we have successfully woken up a
task.
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This introduces the new TRACE_EVENT_FLAGS() macro in order
to set up initial event flags value.
This macro must simply follow the definition of a trace event
and take the event name and the flag value as parameters:
TRACE_EVENT(my_event, .....
....
);
TRACE_EVENT_FLAGS(my_event, 1)
This will set up 1 as the initial my_event->flags value.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Jason Baron <jbaron@redhat.com>
Make use of the jump label infrastructure for tracepoints.
Signed-off-by: Jason Baron <jbaron@redhat.com>
LKML-Reference: <a9ba2056e2c9cf332c3c300b577463ce66ff23a8.1284733808.git.jbaron@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The header file include/linux/tracepoint.h may be included without
include/linux/errno.h and then the compiler will fail on building for
undelcared ENOSYS. This patch fixes this problem via including <linux/errno.h>
to include/linux/tracepoint.h.
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
LKML-Reference: <1277118549-622-1-git-send-email-wuzhangjin@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Zenghui Yu