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They can be unused with certain Kconfig variations:
kernel/events/core.c:9622:13: warning: ‘perf_event_free_bpf_handler’ defined but not used [-Wunused-function]
kernel/events/core.c:9586:12: warning: ‘perf_event_set_bpf_handler’ defined but not used [-Wunused-function]
Since they are both single-use, mark them inline.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org
Cc: Kyle Huey <khuey@kylehuey.com>
Pull misc x86 fixes from Ingo Molnar:
- Follow up fixes for the BHI mitigations code
- Fix !SPECULATION_MITIGATIONS bug not turning off mitigations as
expected
- Work around an APIC emulation bug when the kernel is built with Clang
and run as a SEV guest
- Follow up x86 topology fixes
* tag 'x86-urgent-2024-04-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/cpu/amd: Move TOPOEXT enablement into the topology parser
x86/cpu/amd: Make the NODEID_MSR union actually work
x86/cpu/amd: Make the CPUID 0x80000008 parser correct
x86/bugs: Replace CONFIG_SPECTRE_BHI_{ON,OFF} with CONFIG_MITIGATION_SPECTRE_BHI
x86/bugs: Remove CONFIG_BHI_MITIGATION_AUTO and spectre_bhi=auto
x86/bugs: Clarify that syscall hardening isn't a BHI mitigation
x86/bugs: Fix BHI handling of RRSBA
x86/bugs: Rename various 'ia32_cap' variables to 'x86_arch_cap_msr'
x86/bugs: Cache the value of MSR_IA32_ARCH_CAPABILITIES
x86/bugs: Fix BHI documentation
x86/cpu: Actually turn off mitigations by default for SPECULATION_MITIGATIONS=n
x86/topology: Don't update cpu_possible_map in topo_set_cpuids()
x86/bugs: Fix return type of spectre_bhi_state()
x86/apic: Force native_apic_mem_read() to use the MOV instruction
Pull dma-mapping fixes from Christoph Hellwig:
- fix up swiotlb buffer padding even more (Petr Tesarik)
- fix for partial dma_sync on swiotlb (Michael Kelley)
- swiotlb debugfs fix (Dexuan Cui)
* tag 'dma-maping-6.9-2024-04-14' of git://git.infradead.org/users/hch/dma-mapping:
swiotlb: do not set total_used to 0 in swiotlb_create_debugfs_files()
swiotlb: fix swiotlb_bounce() to do partial sync's correctly
swiotlb: extend buffer pre-padding to alloc_align_mask if necessary
Long ago a map file descriptor in a pseudo ldimm64 instruction could
only be present as an immediate value insn[0].imm, and thus this value
was used in a verbose verifier message printed when the file descriptor
wasn't valid. Since addition of BPF_PSEUDO_MAP_IDX_VALUE/BPF_PSEUDO_MAP_IDX
the insn[0].imm field can also contain an index pointing to the file
descriptor in the attr.fd_array array. However, if the file descriptor
is invalid, the verifier still prints the verbose message containing
value of insn[0].imm. Patch the verifier message to always print the
actual file descriptor value.
Fixes: 387544bfa2 ("bpf: Introduce fd_idx")
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240412141100.3562942-1-aspsk@isovalent.com
Pull tracing fixes from Steven Rostedt:
- Fix the buffer_percent accounting as it is dependent on three
variables:
1) pages_read - number of subbuffers read
2) pages_lost - number of subbuffers lost due to overwrite
3) pages_touched - number of pages that a writer entered
These three counters only increment, and to know how many active
pages there are on the buffer at any given time, the pages_read and
pages_lost are subtracted from pages_touched.
But the pages touched was incremented whenever any writer went to the
next subbuffer even if it wasn't the only one, so it was incremented
more than it should be causing the counter for how many subbuffers
currently have content incorrect, which caused the buffer_percent
that holds waiters until the ring buffer is filled to a given
percentage to wake up early.
- Fix warning of unused functions when PERF_EVENTS is not configured in
- Replace bad tab with space in Kconfig for FTRACE_RECORD_RECURSION_SIZE
- Fix to some kerneldoc function comments in eventfs code.
* tag 'trace-v6.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
ring-buffer: Only update pages_touched when a new page is touched
tracing: hide unused ftrace_event_id_fops
tracing: Fix FTRACE_RECORD_RECURSION_SIZE Kconfig entry
eventfs: Fix kernel-doc comments to functions
When the watchdog determines that the current soft lockup is due to an
interrupt storm based on CPU utilization, reporting the most frequent
interrupts could be good enough for further troubleshooting.
Below is an example of interrupt storm. The call tree does not provide
useful information, but analyzing which interrupt caused the soft lockup by
comparing the counts of interrupts during the lockup period allows to
identify the culprit.
[ 638.870231] watchdog: BUG: soft lockup - CPU#9 stuck for 26s! [swapper/9:0]
[ 638.870825] CPU#9 Utilization every 4s during lockup:
[ 638.871194] #1: 0% system, 0% softirq, 100% hardirq, 0% idle
[ 638.871652] #2: 0% system, 0% softirq, 100% hardirq, 0% idle
[ 638.872107] #3: 0% system, 0% softirq, 100% hardirq, 0% idle
[ 638.872563] #4: 0% system, 0% softirq, 100% hardirq, 0% idle
[ 638.873018] #5: 0% system, 0% softirq, 100% hardirq, 0% idle
[ 638.873494] CPU#9 Detect HardIRQ Time exceeds 50%. Most frequent HardIRQs:
[ 638.873994] #1: 330945 irq#7
[ 638.874236] #2: 31 irq#82
[ 638.874493] #3: 10 irq#10
[ 638.874744] #4: 2 irq#89
[ 638.874992] #5: 1 irq#102
...
[ 638.875313] Call trace:
[ 638.875315] __do_softirq+0xa8/0x364
Signed-off-by: Bitao Hu <yaoma@linux.alibaba.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Liu Song <liusong@linux.alibaba.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20240411074134.30922-6-yaoma@linux.alibaba.com
The following softlockup is caused by interrupt storm, but it cannot be
identified from the call tree. Because the call tree is just a snapshot
and doesn't fully capture the behavior of the CPU during the soft lockup.
watchdog: BUG: soft lockup - CPU#28 stuck for 23s! [fio:83921]
...
Call trace:
__do_softirq+0xa0/0x37c
__irq_exit_rcu+0x108/0x140
irq_exit+0x14/0x20
__handle_domain_irq+0x84/0xe0
gic_handle_irq+0x80/0x108
el0_irq_naked+0x50/0x58
Therefore, it is necessary to report CPU utilization during the
softlockup_threshold period (report once every sample_period, for a total
of 5 reportings), like this:
watchdog: BUG: soft lockup - CPU#28 stuck for 23s! [fio:83921]
CPU#28 Utilization every 4s during lockup:
#1: 0% system, 0% softirq, 100% hardirq, 0% idle
#2: 0% system, 0% softirq, 100% hardirq, 0% idle
#3: 0% system, 0% softirq, 100% hardirq, 0% idle
#4: 0% system, 0% softirq, 100% hardirq, 0% idle
#5: 0% system, 0% softirq, 100% hardirq, 0% idle
...
This is helpful in determining whether an interrupt storm has occurred or
in identifying the cause of the softlockup. The criteria for determination
are as follows:
a. If the hardirq utilization is high, then interrupt storm should be
considered and the root cause cannot be determined from the call tree.
b. If the softirq utilization is high, then the call might not necessarily
point at the root cause.
c. If the system utilization is high, then analyzing the root
cause from the call tree is possible in most cases.
The mechanism requires a considerable amount of global storage space
when configured for the maximum number of CPUs. Therefore, adding a
SOFTLOCKUP_DETECTOR_INTR_STORM Kconfig knob that defaults to "yes"
if the max number of CPUs is <= 128.
Signed-off-by: Bitao Hu <yaoma@linux.alibaba.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Liu Song <liusong@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240411074134.30922-5-yaoma@linux.alibaba.com
show_interrupts() unconditionally accumulates the per CPU interrupt
statistics to determine whether an interrupt was ever raised.
This can be avoided for all interrupts which are not strictly per CPU
and not of type NMI because those interrupts provide already an
accumulated counter. The required logic is already implemented in
kstat_irqs().
Split the inner access logic out of kstat_irqs() and use it for
kstat_irqs() and show_interrupts() to avoid the accumulation loop
when possible.
Originally-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Bitao Hu <yaoma@linux.alibaba.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Liu Song <liusong@linux.alibaba.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20240411074134.30922-4-yaoma@linux.alibaba.com
The soft lockup detector lacks a mechanism to identify interrupt storms as
root cause of a lockup. To enable this the detector needs a mechanism to
snapshot the interrupt count statistics on a CPU when the detector observes
a potential lockup scenario and compare that against the interrupt count
when it warns about the lockup later on. The number of interrupts in that
period give a hint whether the lockup might have been caused by an interrupt
storm.
Instead of having extra storage in the lockup detector and accessing the
internals of the interrupt descriptor directly, add a snapshot member to
the per CPU irq_desc::kstat_irq structure and provide interfaces to take a
snapshot of all interrupts on the current CPU and to retrieve the delta of
a specific interrupt later on.
Originally-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Bitao Hu <yaoma@linux.alibaba.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240411074134.30922-3-yaoma@linux.alibaba.com
The irq_desc::kstat_irqs member is a per-CPU variable of type int, which is
only capable of counting. A snapshot mechanism for interrupt statistics
will be added soon, which requires an additional variable to store the
snapshot.
To facilitate expansion, convert kstat_irqs here to a struct containing
only the count.
Originally-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Bitao Hu <yaoma@linux.alibaba.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240411074134.30922-2-yaoma@linux.alibaba.com
To ultimately allow BPF programs attached to perf events to completely
suppress all of the effects of a perf event overflow (rather than just the
sample output, as they do today), call bpf_overflow_handler() from
__perf_event_overflow() directly rather than modifying struct perf_event's
overflow_handler. Return the BPF program's return value from
bpf_overflow_handler() so that __perf_event_overflow() knows how to
proceed. Remove the now unnecessary orig_overflow_handler from struct
perf_event.
This patch is solely a refactoring and results in no behavior change.
Suggested-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Kyle Huey <khuey@kylehuey.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240412015019.7060-5-khuey@kylehuey.com
Replace this pattern in trylock_clear_pending():
cmpxchg_acquire(*ptr, old, new) == old
... with the simpler and faster:
try_cmpxchg_acquire(*ptr, &old, new)
The x86 CMPXCHG instruction returns success in the ZF flag, so this change
saves a compare after the CMPXCHG.
Also change the return type of the function to bool and streamline
the control flow in the _Q_PENDING_BITS == 8 variant a bit.
No functional change intended.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Waiman Long <longman@redhat.com>
Reviewed-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20240325140943.815051-1-ubizjak@gmail.com
The advent of CONFIG_PREEMPT_AUTO, AKA lazy preemption, will mean that
even kernels built with CONFIG_PREEMPT_NONE or CONFIG_PREEMPT_VOLUNTARY
might see the occasional preemption, and that this preemption just might
happen within a trampoline.
Therefore, update ftrace_shutdown() to invoke synchronize_rcu_tasks()
based on CONFIG_TASKS_RCU instead of CONFIG_PREEMPTION.
[ paulmck: Apply Steven Rostedt feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Ankur Arora <ankur.a.arora@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <linux-trace-kernel@vger.kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
The "buffer_percent" logic that is used by the ring buffer splice code to
only wake up the tasks when there's no data after the buffer is filled to
the percentage of the "buffer_percent" file is dependent on three
variables that determine the amount of data that is in the ring buffer:
1) pages_read - incremented whenever a new sub-buffer is consumed
2) pages_lost - incremented every time a writer overwrites a sub-buffer
3) pages_touched - incremented when a write goes to a new sub-buffer
The percentage is the calculation of:
(pages_touched - (pages_lost + pages_read)) / nr_pages
Basically, the amount of data is the total number of sub-bufs that have been
touched, minus the number of sub-bufs lost and sub-bufs consumed. This is
divided by the total count to give the buffer percentage. When the
percentage is greater than the value in the "buffer_percent" file, it
wakes up splice readers waiting for that amount.
It was observed that over time, the amount read from the splice was
constantly decreasing the longer the trace was running. That is, if one
asked for 60%, it would read over 60% when it first starts tracing, but
then it would be woken up at under 60% and would slowly decrease the
amount of data read after being woken up, where the amount becomes much
less than the buffer percent.
This was due to an accounting of the pages_touched incrementation. This
value is incremented whenever a writer transfers to a new sub-buffer. But
the place where it was incremented was incorrect. If a writer overflowed
the current sub-buffer it would go to the next one. If it gets preempted
by an interrupt at that time, and the interrupt performs a trace, it too
will end up going to the next sub-buffer. But only one should increment
the counter. Unfortunately, that was not the case.
Change the cmpxchg() that does the real switch of the tail-page into a
try_cmpxchg(), and on success, perform the increment of pages_touched. This
will only increment the counter once for when the writer moves to a new
sub-buffer, and not when there's a race and is incremented for when a
writer and its preempting writer both move to the same new sub-buffer.
Link: https://lore.kernel.org/linux-trace-kernel/20240409151309.0d0e5056@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes: 2c2b0a78b3 ("ring-buffer: Add percentage of ring buffer full to wake up reader")
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Pull power management fix from Rafael Wysocki:
"Fix the suspend-to-idle core code to guarantee that timers queued on
CPUs other than the one that has first left the idle state, which
should expire directly after resume, will be handled (Anna-Maria
Behnsen)"
* tag 'pm-6.9-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
PM: s2idle: Make sure CPUs will wakeup directly on resume
Using of devm API leads to a certain order of releasing resources.
So all dependent resources which are not devm-wrapped should be deleted
with respect to devm-release order. Mutex is one of such objects that
often is bound to other resources and has no own devm wrapping.
Since mutex_destroy() actually does nothing in non-debug builds
frequently calling mutex_destroy() is just ignored which is safe for now
but wrong formally and can lead to a problem if mutex_destroy() will be
extended so introduce devm_mutex_init().
Suggested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: George Stark <gnstark@salutedevices.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Marek Behún <kabel@kernel.org>
Acked-by: Waiman Long <longman@redhat.com>
Link: https://lore.kernel.org/r/20240411161032.609544-2-gnstark@salutedevices.com
Signed-off-by: Lee Jones <lee@kernel.org>
Currently, if a Kconfig option depends on TASKS_RCU, it conditionally does
"select TASKS_RCU if PREEMPTION". This works, but requires any change in
this enablement logic to be replicated across all such "select" clauses.
A new NEED_TASKS_RCU Kconfig option has been created to allow this
enablement logic to be in one place in kernel/rcu/Kconfig.
Therefore, select the new NEED_TASKS_RCU Kconfig option instead of the
old TASKS_RCU option.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: <linux-trace-kernel@vger.kernel.org>
Cc: Ankur Arora <ankur.a.arora@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
The synchronize_rcu() call is going to be reworked, thus
this patch adds dedicated fields into the rcu_state structure.
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Use atomic_try_cmpxchg_relaxed(*ptr, &old, new) instead of
atomic_cmpxchg_relaxed (*ptr, old, new) == old in xchg_tail().
x86 CMPXCHG instruction returns success in ZF flag,
so this change saves a compare after CMPXCHG.
No functional change intended.
Since this code requires NR_CPUS >= 16k, I have tested it
by unconditionally setting _Q_PENDING_BITS to 1 in
<asm-generic/qspinlock_types.h>.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Waiman Long <longman@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20240321195309.484275-1-ubizjak@gmail.com
Add a generic function console_replay_all() for replaying
the kernel log on consoles, in any context. It would allow
viewing the logs on an unresponsive terminal via sysrq.
Reuse the existing code from console_flush_on_panic() for
resetting the sequence numbers, by introducing a new helper
function __console_rewind_all(). It is safe to be called
under console_lock().
Try to acquire lock on the console subsystem without waiting.
If successful, reset the sequence number to oldest available
record on all consoles and call console_unlock() which will
automatically flush the messages to the consoles.
Suggested-by: John Ogness <john.ogness@linutronix.de>
Suggested-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Shimoyashiki Taichi <taichi.shimoyashiki@sony.com>
Reviewed-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Sreenath Vijayan <sreenath.vijayan@sony.com>
Link: https://lore.kernel.org/r/90ee131c643a5033d117b556c0792de65129d4c3.1710220326.git.sreenath.vijayan@sony.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add bpf_link support for sk_msg and sk_skb programs. We have an
internal request to support bpf_link for sk_msg programs so user
space can have a uniform handling with bpf_link based libbpf
APIs. Using bpf_link based libbpf API also has a benefit which
makes system robust by decoupling prog life cycle and
attachment life cycle.
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240410043527.3737160-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When unloading a module, its state is changing MODULE_STATE_LIVE ->
MODULE_STATE_GOING -> MODULE_STATE_UNFORMED. Each change will take
a time. `is_module_text_address()` and `__module_text_address()`
works with MODULE_STATE_LIVE and MODULE_STATE_GOING.
If we use `is_module_text_address()` and `__module_text_address()`
separately, there is a chance that the first one is succeeded but the
next one is failed because module->state becomes MODULE_STATE_UNFORMED
between those operations.
In `check_kprobe_address_safe()`, if the second `__module_text_address()`
is failed, that is ignored because it expected a kernel_text address.
But it may have failed simply because module->state has been changed
to MODULE_STATE_UNFORMED. In this case, arm_kprobe() will try to modify
non-exist module text address (use-after-free).
To fix this problem, we should not use separated `is_module_text_address()`
and `__module_text_address()`, but use only `__module_text_address()`
once and do `try_module_get(module)` which is only available with
MODULE_STATE_LIVE.
Link: https://lore.kernel.org/all/20240410015802.265220-1-zhengyejian1@huawei.com/
Fixes: 28f6c37a29 ("kprobes: Forbid probing on trampoline and BPF code areas")
Cc: stable@vger.kernel.org
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Initialize cpu_mitigations to CPU_MITIGATIONS_OFF if the kernel is built
with CONFIG_SPECULATION_MITIGATIONS=n, as the help text quite clearly
states that disabling SPECULATION_MITIGATIONS is supposed to turn off all
mitigations by default.
│ If you say N, all mitigations will be disabled. You really
│ should know what you are doing to say so.
As is, the kernel still defaults to CPU_MITIGATIONS_AUTO, which results in
some mitigations being enabled in spite of SPECULATION_MITIGATIONS=n.
Fixes: f43b9876e8 ("x86/retbleed: Add fine grained Kconfig knobs")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Cc: stable@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20240409175108.1512861-2-seanjc@google.com
tick_do_timer_cpu is used lockless to check which CPU needs to take care
of the per tick timekeeping duty. This is done to avoid a thundering
herd problem on jiffies_lock.
The read and writes are not annotated so KCSAN complains about data races:
BUG: KCSAN: data-race in tick_nohz_idle_stop_tick / tick_nohz_next_event
write to 0xffffffff8a2bda30 of 4 bytes by task 0 on cpu 26:
tick_nohz_idle_stop_tick+0x3b1/0x4a0
do_idle+0x1e3/0x250
read to 0xffffffff8a2bda30 of 4 bytes by task 0 on cpu 16:
tick_nohz_next_event+0xe7/0x1e0
tick_nohz_get_sleep_length+0xa7/0xe0
menu_select+0x82/0xb90
cpuidle_select+0x44/0x60
do_idle+0x1c2/0x250
value changed: 0x0000001a -> 0xffffffff
Annotate them with READ/WRITE_ONCE() to document the intentional data race.
Reported-by: Mirsad Todorovac <mirsad.todorovac@alu.unizg.hr>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Sean Anderson <sean.anderson@seco.com>
Link: https://lore.kernel.org/r/87cyqy7rt3.ffs@tglx
In perf_adjust_freq_unthr_context(), it first starts the event and then
stop unnecessarily to adjust the sampling frequency if the event is
throttled.
For a throttled non-frequency event, it doesn't have a freq so no need
to adjust. Just starting the event would be ok.
For a frequency event, whether it's throttled or not, it needs to stop
before adjusting the frequency. That means it should not start the
even if it was throttled. I tried to skip calling the stop callback,
but it didn't work well since the event count might not be up to date.
It should call the stop callback with PERF_EF_UPDATE anyway.
However not calling start would prevent unnecessary MSR accesses (which
can be costly) for already stopped events as stop state is saved in the
hw config.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Ian Rogers <irogers@google.com>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20240207050545.2727923-2-namhyung@kernel.org
It was unnecessarily disabling and enabling PMUs for each event. It
should be done at PMU level. Add pmu_ctx->nr_freq counter to check it
at each PMU. As PMU context has separate active lists for pinned group
and flexible group, factor out a new function to do the job.
Another minor optimization is that it can skip PMUs w/ CAP_NO_INTERRUPT
even if it needs to unthrottle sampling events.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Mingwei Zhang <mizhang@google.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20240207050545.2727923-1-namhyung@kernel.org
Support atomics in bpf_arena that can be JITed as a single x86 instruction.
Instructions that are JITed as loops are not supported at the moment,
since they require more complex extable and loop logic.
JITs can choose to do smarter things with bpf_jit_supports_insn().
Like arm64 may decide to support all bpf atomics instructions
when emit_lse_atomic is available and none in ll_sc mode.
bpf_jit_supports_percpu_insn(), bpf_jit_supports_ptr_xchg() and
other such callbacks can be replaced with bpf_jit_supports_insn()
in the future.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240405231134.17274-1-alexei.starovoitov@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
If add_preferred_console() is not called early in setup_console(), we can
end up having register_console() call try_enable_default_console() before a
console device has called add_preferred_console().
Let's set console_set_on_cmdline flag in console_setup() to prevent this
from happening.
Signed-off-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20240327110021.59793-4-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Driver subsystems may need to translate the preferred console name to the
character device name used. We already do some of this in console_setup()
with a few hardcoded names, but that does not scale well.
The console options are parsed early in console_setup(), and the consoles
are added with __add_preferred_console(). At this point we don't know much
about the character device names and device drivers getting probed.
To allow driver subsystems to set up a preferred console, let's save the
kernel command line console options. To add a preferred console from a
driver subsystem with optional character device name translation, let's
add a new function add_preferred_console_match().
This allows the serial core layer to support console=DEVNAME:0.0 style
hardware based addressing in addition to the current console=ttyS0 style
naming. And we can start moving console_setup() character device parsing
to the driver subsystem specific code.
We use a separate array from the console_cmdline array as the character
device name and index may be unknown at the console_setup() time. And
eventually there's no need to call __add_preferred_console() until the
subsystem is ready to handle the console.
Adding the console name in addition to the character device name, and a
flag for an added console, could be added to the struct console_cmdline.
And the console_cmdline array handling could be modified accordingly. But
that complicates things compared saving the console options, and then
adding the consoles when the subsystems handling the consoles are ready.
Co-developed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240327110021.59793-2-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently, all waits for grace periods sleep at TASK_UNINTERRUPTIBLE,
regardless of RCU flavor. This has worked well, but there have been
cases where a longer-than-average Tasks RCU grace period has triggered
softlockup splats, many of them, before the Tasks RCU CPU stall warning
appears. These softlockup splats unnecessarily consume console bandwidth
and complicate diagnosis of the underlying problem. Plus a long but not
pathologically long Tasks RCU grace period might trigger a few softlockup
splats before completing normally, which generates noise for no good
reason.
This commit therefore causes Tasks RCU grace periods to sleep at TASK_IDLE
priority. If there really is a persistent problem, the eventual Tasks
RCU CPU stall warning will flag it, and without the extra noise.
Reported-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
It turns out that only one CPU at a time will ever invoke
rcu_torture_pipe_update_one() on a given rcu_torture structure.
This commit therefore adds three ASSERT_EXCLUSIVE_WRITER() calls
to enlist KCSAN's aid in checking this.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
If a callback flood prevents grace period from completing, rcutorture
does a WARN_ON(). Avoiding this WARN_ON() currently requires that at
least three grace periods elapse during an eight-second callback-flood
interval. Unfortunately, the current debug information does not include
anything about the grace-period state. This commit therefore adds a
call to cur_ops->gp_kthread_dbg(), if this function pointer is non-NULL.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
