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 f37755490fe9b ("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 3a630178fd5f3 ("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 f37755490fe9b 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: f37755490fe9b ("tracepoints: Do not trace when cpu is offline")
Fixes: 3a630178fd5f3 ("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: 97e1c18e8d17b ("tracing: Kernel Tracepoints")
Cc: stable@vger.kernel.org # v2.6.28+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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>