Merge: Rebase RTLA to v6.17 [rhel-9.8]

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/7554

# Merge Request Required Information

JIRA: https://issues.redhat.com/browse/RHEL-117873

CVE: CVE-2025-38493
CVE: CVE-2025-39887
CVE: CVE-2025-39974
CVE: CVE-2025-21733

## Summary of Changes

Rebase RTLA in RHEL 9.8 to upstream 6.17, with one fix from 6.18.

## Approved Development Ticket(s)
All submissions to CentOS Stream must reference a ticket in [Red Hat Jira](https://issues.redhat.com/).

<details><summary>Click for formatting instructions</summary>
Please follow the CentOS Stream [contribution documentation](https://docs.centos.org/en-US/stream-contrib/quickstart/) for how to file this ticket and have it approved.

List tickets each on their own line of this description using the format "Resolves: RHEL-76229", "Related: RHEL-76229" or "Reverts: RHEL-76229", as appropriate.
</details>

Signed-off-by: Tomas Glozar <tglozar@redhat.com>

Approved-by: Phil Auld <pauld@redhat.com>
Approved-by: Wander Lairson Costa <wander@redhat.com>
Approved-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: CKI GitLab Kmaint Pipeline Bot <26919896-cki-kmaint-pipeline-bot@users.noreply.gitlab.com>

Author: CKI KWF Bot

Documentation/tools/rtla/common_options.rst

@@ -14,10 +14,6 @@
 
         Print debug info.
 
-**-t**, **--trace**\[*=file*]
-
-        Save the stopped trace to [*file|osnoise_trace.txt*].
-
 **-e**, **--event** *sys:event*
 
         Enable an event in the trace (**-t**) session. The argument can be a specific event, e.g., **-e** *sched:sched_switch*, or all events of a system group, e.g., **-e** *sched*. Multiple **-e** are allowed. It is only active when **-t** or **-a** are set.

Documentation/tools/rtla/common_osnoise_options.rst

@@ -25,3 +25,7 @@
 
         Specify the minimum delta between two time reads to be considered noise.
         The default threshold is *5 us*.
+
+**-t**, **--trace** \[*file*]
+
+        Save the stopped trace to [*file|osnoise_trace.txt*].

Documentation/tools/rtla/common_timerlat_description.rst

@@ -6,5 +6,13 @@ debugging of operating system timer latency.
 
 The *timerlat* tracer outputs information in two ways. It periodically
 prints the timer latency at the timer *IRQ* handler and the *Thread*
-handler. It also enable the trace of the most relevant information via
+handler. It also enables the trace of the most relevant information via
 **osnoise:** tracepoints.
+
+The **rtla timerlat** tool sets the options of the *timerlat* tracer
+and collects and displays a summary of the results. By default,
+the collection is done synchronously in kernel space using a dedicated
+BPF program attached to the *timerlat* tracer. If either BPF or
+the **osnoise:timerlat_sample** tracepoint it attaches to is
+unavailable, the **rtla timerlat** tool falls back to using tracefs to
+process the data asynchronously in user space.

Documentation/tools/rtla/common_timerlat_options.rst

@@ -22,6 +22,10 @@
         Save the stack trace at the *IRQ* if a *Thread* latency is higher than the
         argument in us.
 
+**-t**, **--trace** \[*file*]
+
+        Save the stopped trace to [*file|timerlat_trace.txt*].
+
 **--dma-latency** *us*
         Set the /dev/cpu_dma_latency to *us*, aiming to bound exit from idle latencies.
         *cyclictest* sets this value to *0* by default, use **--dma-latency** *0* to have

Documentation/tools/rtla/rtla-timerlat-hist.rst

@@ -36,11 +36,11 @@ EXAMPLE
 In the example below, **rtla timerlat hist** is set to run for *10* minutes,
 in the cpus *0-4*, *skipping zero* only lines. Moreover, **rtla timerlat
 hist** will change the priority of the *timerlat* threads to run under
-*SCHED_DEADLINE* priority, with a *10us* runtime every *1ms* period. The
+*SCHED_DEADLINE* priority, with a *100us* runtime every *1ms* period. The
 *1ms* period is also passed to the *timerlat* tracer. Auto-analysis is disabled
 to reduce overhead ::
 
-  [root@alien ~]# timerlat hist -d 10m -c 0-4 -P d:100us:1ms -p 1ms --no-aa
+  [root@alien ~]# timerlat hist -d 10m -c 0-4 -P d:100us:1ms -p 1000 --no-aa
   # RTLA timerlat histogram
   # Time unit is microseconds (us)
   # Duration:   0 00:10:00
@@ -107,3 +107,5 @@ SEE ALSO
 AUTHOR
 ======
 Written by Daniel Bristot de Oliveira <bristot@kernel.org>
+
+.. include:: common_appendix.rst

Documentation/tools/rtla/rtla-timerlat.rst

@@ -16,13 +16,10 @@ DESCRIPTION
 
 .. include:: common_timerlat_description.rst
 
-The *timerlat* tracer outputs information in two ways. It periodically
-prints the timer latency at the timer *IRQ* handler and the *Thread* handler.
-It also provides information for each noise via the **osnoise:** tracepoints.
 The **rtla timerlat top** mode displays a summary of the periodic output
-from the *timerlat* tracer. The **rtla hist hist** mode displays a histogram
-of each tracer event occurrence. For further details, please refer to the
-respective man page.
+from the *timerlat* tracer. The **rtla timerlat hist** mode displays
+a histogram of each tracer event occurrence. For further details, please
+refer to the respective man page.
 
 MODES
 =====

kernel/trace/trace_osnoise.c

@@ -24,6 +24,7 @@
 #include <linux/sched/clock.h>
 #include <uapi/linux/sched/types.h>
 #include <linux/sched.h>
+#include <linux/string.h>
 #include "trace.h"
 
 #ifdef CONFIG_X86_LOCAL_APIC
@@ -271,7 +272,7 @@ static inline void tlat_var_reset(void)
 	 * So far, all the values are initialized as 0, so
 	 * zeroing the structure is perfect.
 	 */
-	for_each_cpu(cpu, cpu_online_mask) {
+	for_each_online_cpu(cpu) {
 		tlat_var = per_cpu_ptr(&per_cpu_timerlat_var, cpu);
 		if (tlat_var->kthread)
 			hrtimer_cancel(&tlat_var->timer);
@@ -295,7 +296,7 @@ static inline void osn_var_reset(void)
 	 * So far, all the values are initialized as 0, so
 	 * zeroing the structure is perfect.
 	 */
-	for_each_cpu(cpu, cpu_online_mask) {
+	for_each_online_cpu(cpu) {
 		osn_var = per_cpu_ptr(&per_cpu_osnoise_var, cpu);
 		memset(osn_var, 0, sizeof(*osn_var));
 	}
@@ -642,8 +643,8 @@ __timerlat_dump_stack(struct trace_buffer *buffer, struct trace_stack *fstack, u
 
 	entry = ring_buffer_event_data(event);
 
-	memcpy(&entry->caller, fstack->calls, size);
 	entry->size = fstack->nr_entries;
+	memcpy(&entry->caller, fstack->calls, size);
 
 	if (!call_filter_check_discard(call, entry, buffer, event))
 		trace_buffer_unlock_commit_nostack(buffer, event);
@@ -1212,6 +1213,8 @@ static void trace_sched_migrate_callback(void *data, struct task_struct *p, int
 	}
 }
 
+static bool monitor_enabled;
+
 static int register_migration_monitor(void)
 {
 	int ret = 0;
@@ -1220,16 +1223,25 @@ static int register_migration_monitor(void)
 	 * Timerlat thread migration check is only required when running timerlat in user-space.
 	 * Thus, enable callback only if timerlat is set with no workload.
 	 */
-	if (timerlat_enabled() && !test_bit(OSN_WORKLOAD, &osnoise_options))
+	if (timerlat_enabled() && !test_bit(OSN_WORKLOAD, &osnoise_options)) {
+		if (WARN_ON_ONCE(monitor_enabled))
+			return 0;
+
 		ret = register_trace_sched_migrate_task(trace_sched_migrate_callback, NULL);
+		if (!ret)
+			monitor_enabled = true;
+	}
 
 	return ret;
 }
 
 static void unregister_migration_monitor(void)
 {
-	if (timerlat_enabled() && !test_bit(OSN_WORKLOAD, &osnoise_options))
-		unregister_trace_sched_migrate_task(trace_sched_migrate_callback, NULL);
+	if (!monitor_enabled)
+		return;
+
+	unregister_trace_sched_migrate_task(trace_sched_migrate_callback, NULL);
+	monitor_enabled = false;
 }
 #else
 static int register_migration_monitor(void)
@@ -1514,27 +1526,25 @@ static int run_osnoise(void)
 
 		/*
 		 * In some cases, notably when running on a nohz_full CPU with
-		 * a stopped tick PREEMPT_RCU has no way to account for QSs.
-		 * This will eventually cause unwarranted noise as PREEMPT_RCU
-		 * will force preemption as the means of ending the current
-		 * grace period. We avoid this problem by calling
-		 * rcu_momentary_eqs(), which performs a zero duration
-		 * EQS allowing PREEMPT_RCU to end the current grace period.
-		 * This call shouldn't be wrapped inside an RCU critical
-		 * section.
+		 * a stopped tick PREEMPT_RCU or PREEMPT_LAZY have no way to
+		 * account for QSs. This will eventually cause unwarranted
+		 * noise as RCU forces preemption as the means of ending the
+		 * current grace period.  We avoid this by calling
+		 * rcu_momentary_eqs(), which performs a zero duration EQS
+		 * allowing RCU to end the current grace period. This call
+		 * shouldn't be wrapped inside an RCU critical section.
 		 *
-		 * Note that in non PREEMPT_RCU kernels QSs are handled through
-		 * cond_resched()
+		 * Normally QSs for other cases are handled through cond_resched().
+		 * For simplicity, however, we call rcu_momentary_eqs() for all
+		 * configurations here.
 		 */
-		if (IS_ENABLED(CONFIG_PREEMPT_RCU)) {
-			if (!disable_irq)
-				local_irq_disable();
+		if (!disable_irq)
+			local_irq_disable();
 
-			rcu_momentary_eqs();
+		rcu_momentary_eqs();
 
-			if (!disable_irq)
-				local_irq_enable();
-		}
+		if (!disable_irq)
+			local_irq_enable();
 
 		/*
 		 * For the non-preemptive kernel config: let threads runs, if
@@ -1873,8 +1883,7 @@ static int timerlat_main(void *data)
 	tlat->count = 0;
 	tlat->tracing_thread = false;
 
-	hrtimer_init(&tlat->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED_HARD);
-	tlat->timer.function = timerlat_irq;
+	hrtimer_setup(&tlat->timer, timerlat_irq, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED_HARD);
 	tlat->kthread = current;
 	osn_var->pid = current->pid;
 	/*
@@ -2004,7 +2013,6 @@ static int start_kthread(unsigned int cpu)
 
 	if (IS_ERR(kthread)) {
 		pr_err(BANNER "could not start sampling thread\n");
-		stop_per_cpu_kthreads();
 		return -ENOMEM;
 	}
 
@@ -2066,26 +2074,21 @@ static void osnoise_hotplug_workfn(struct work_struct *dummy)
 {
 	unsigned int cpu = smp_processor_id();
 
-	mutex_lock(&trace_types_lock);
+	guard(mutex)(&trace_types_lock);
 
 	if (!osnoise_has_registered_instances())
-		goto out_unlock_trace;
+		return;
 
-	mutex_lock(&interface_lock);
-	cpus_read_lock();
+	guard(mutex)(&interface_lock);
+	guard(cpus_read_lock)();
 
 	if (!cpu_online(cpu))
-		goto out_unlock;
+		return;
+
 	if (!cpumask_test_cpu(cpu, &osnoise_cpumask))
-		goto out_unlock;
+		return;
 
 	start_kthread(cpu);
-
-out_unlock:
-	cpus_read_unlock();
-	mutex_unlock(&interface_lock);
-out_unlock_trace:
-	mutex_unlock(&trace_types_lock);
 }
 
 static DECLARE_WORK(osnoise_hotplug_work, osnoise_hotplug_workfn);
@@ -2283,31 +2286,22 @@ static ssize_t
 osnoise_cpus_read(struct file *filp, char __user *ubuf, size_t count,
 		  loff_t *ppos)
 {
-	char *mask_str;
+	char *mask_str __free(kfree) = NULL;
 	int len;
 
-	mutex_lock(&interface_lock);
+	guard(mutex)(&interface_lock);
 
 	len = snprintf(NULL, 0, "%*pbl\n", cpumask_pr_args(&osnoise_cpumask)) + 1;
 	mask_str = kmalloc(len, GFP_KERNEL);
-	if (!mask_str) {
-		count = -ENOMEM;
-		goto out_unlock;
-	}
+	if (!mask_str)
+		return -ENOMEM;
 
 	len = snprintf(mask_str, len, "%*pbl\n", cpumask_pr_args(&osnoise_cpumask));
-	if (len >= count) {
-		count = -EINVAL;
-		goto out_free;
-	}
+	if (len >= count)
+		return -EINVAL;
 
 	count = simple_read_from_buffer(ubuf, count, ppos, mask_str, len);
 
-out_free:
-	kfree(mask_str);
-out_unlock:
-	mutex_unlock(&interface_lock);
-
 	return count;
 }
 
@@ -2335,12 +2329,12 @@ osnoise_cpus_write(struct file *filp, const char __user *ubuf, size_t count,
 	int running, err;
 	char *buf __free(kfree) = NULL;
 
-	buf = kmalloc(count, GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
+	if (count < 1)
+		return 0;
 
-	if (copy_from_user(buf, ubuf, count))
-		return -EFAULT;
+	buf = memdup_user_nul(ubuf, count);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
 
 	if (!zalloc_cpumask_var(&osnoise_cpumask_new, GFP_KERNEL))
 		return -ENOMEM;
@@ -2443,8 +2437,7 @@ static int timerlat_fd_open(struct inode *inode, struct file *file)
 	tlat = this_cpu_tmr_var();
 	tlat->count = 0;
 
-	hrtimer_init(&tlat->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED_HARD);
-	tlat->timer.function = timerlat_irq;
+	hrtimer_setup(&tlat->timer, timerlat_irq, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED_HARD);
 
 	migrate_enable();
 	return 0;

tools/tracing/rtla/Makefile.config

@@ -1,10 +1,18 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
+include $(srctree)/tools/scripts/utilities.mak
+
 STOP_ERROR :=
 
 LIBTRACEEVENT_MIN_VERSION = 1.5
 LIBTRACEFS_MIN_VERSION = 1.6
 
+ifndef ($(NO_LIBTRACEEVENT),1)
+  ifeq ($(call get-executable,$(PKG_CONFIG)),)
+    $(error Error: $(PKG_CONFIG) needed by libtraceevent/libtracefs is missing on this system, please install it)
+  endif
+endif
+
 define lib_setup
   $(eval LIB_INCLUDES += $(shell sh -c "$(PKG_CONFIG) --cflags lib$(1)"))
   $(eval LDFLAGS += $(shell sh -c "$(PKG_CONFIG) --libs-only-L lib$(1)"))

tools/tracing/rtla/Makefile.rtla

@@ -34,6 +34,8 @@ INSTALL		:= install
 MKDIR		:= mkdir
 STRIP		:= strip
 BINDIR		:= /usr/bin
+CTAGS		:= ctags
+ETAGS		:= ctags -e
 
 .PHONY: install
 install: doc_install
@@ -47,6 +49,18 @@ install: doc_install
 	@test ! -f $(DESTDIR)$(BINDIR)/timerlat || $(RM) $(DESTDIR)$(BINDIR)/timerlat
 	@$(LN) -s rtla $(DESTDIR)$(BINDIR)/timerlat
 
+.PHONY: tags
+tags:
+	$(CTAGS) -R --extras=+f --c-kinds=+p src
+
+.PHONY: TAGS
+TAGS:
+	$(ETAGS) -R --extras=+f --c-kinds=+p src
+
+.PHONY: tags_clean
+tags_clean:
+	$(RM) tags TAGS
+
 .PHONY: doc doc_clean doc_install
 doc:
 	$(MAKE) -C $(DOCSRC)
@@ -57,8 +71,7 @@ doc_clean:
 doc_install:
 	$(MAKE) -C $(DOCSRC) install
 
-# This section is neesary for the tarball, when the tarball
-# support is removed, we can delete these entries.
+# This section is necessary to make the rtla tarball
 NAME		:= rtla
 DIRS		:= src
 FILES		:= Makefile README.txt

tools/tracing/rtla/README.txt

@@ -13,6 +13,13 @@ RTLA depends on the following libraries and tools:
  - libtraceevent
  - libcpupower (optional, for --deepest-idle-state)
 
+For BPF sample collection support, the following extra dependencies are
+required:
+
+ - libbpf 1.0.0 or later
+ - bpftool with skeleton support
+ - clang with BPF CO-RE support
+
 It also depends on python3-docutils to compile man pages.
 
 For development, we suggest the following steps for compiling rtla: