* [PATCH v4 12/14] rv: Replace tss and sncid monitors with more complete sts
[not found] <20250721082325.71554-1-gmonaco@redhat.com>
@ 2025-07-21 8:23 ` Gabriele Monaco
2025-07-21 15:15 ` Nam Cao
2025-07-21 8:23 ` [PATCH v4 13/14] rv: Add nrp and sssw per-task monitors Gabriele Monaco
2025-07-21 8:23 ` [PATCH v4 14/14] rv: Add opid per-cpu monitor Gabriele Monaco
2 siblings, 1 reply; 5+ messages in thread
From: Gabriele Monaco @ 2025-07-21 8:23 UTC (permalink / raw)
To: linux-kernel, Steven Rostedt, Jonathan Corbet, Masami Hiramatsu,
linux-trace-kernel, linux-doc
Cc: Gabriele Monaco, Ingo Molnar, Peter Zijlstra, Nam Cao,
Tomas Glozar, Juri Lelli, Clark Williams, John Kacur
The tss monitor currently guarantees task switches can happen only while
scheduling, whereas the sncid monitor enforces scheduling occurs with
interrupt disabled.
Replace the monitors with a more comprehensive specification which
implies both but also ensures that:
* each scheduler call disable interrupts to switch
* each task switch happens with interrupts disabled
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
fixup sts remove sncid
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
---
Documentation/trace/rv/monitor_sched.rst | 87 +++++-----
kernel/trace/rv/Kconfig | 3 +-
kernel/trace/rv/Makefile | 3 +-
kernel/trace/rv/monitors/sncid/Kconfig | 15 --
kernel/trace/rv/monitors/sncid/sncid.c | 95 -----------
kernel/trace/rv/monitors/sncid/sncid.h | 49 ------
kernel/trace/rv/monitors/sncid/sncid_trace.h | 15 --
kernel/trace/rv/monitors/sts/Kconfig | 19 +++
kernel/trace/rv/monitors/sts/sts.c | 156 ++++++++++++++++++
kernel/trace/rv/monitors/sts/sts.h | 117 +++++++++++++
.../{tss/tss_trace.h => sts/sts_trace.h} | 8 +-
kernel/trace/rv/monitors/tss/Kconfig | 14 --
kernel/trace/rv/monitors/tss/tss.c | 90 ----------
kernel/trace/rv/monitors/tss/tss.h | 47 ------
kernel/trace/rv/rv_trace.h | 3 +-
tools/verification/models/sched/sncid.dot | 18 --
tools/verification/models/sched/sts.dot | 38 +++++
tools/verification/models/sched/tss.dot | 18 --
18 files changed, 385 insertions(+), 410 deletions(-)
delete mode 100644 kernel/trace/rv/monitors/sncid/Kconfig
delete mode 100644 kernel/trace/rv/monitors/sncid/sncid.c
delete mode 100644 kernel/trace/rv/monitors/sncid/sncid.h
delete mode 100644 kernel/trace/rv/monitors/sncid/sncid_trace.h
create mode 100644 kernel/trace/rv/monitors/sts/Kconfig
create mode 100644 kernel/trace/rv/monitors/sts/sts.c
create mode 100644 kernel/trace/rv/monitors/sts/sts.h
rename kernel/trace/rv/monitors/{tss/tss_trace.h => sts/sts_trace.h} (67%)
delete mode 100644 kernel/trace/rv/monitors/tss/Kconfig
delete mode 100644 kernel/trace/rv/monitors/tss/tss.c
delete mode 100644 kernel/trace/rv/monitors/tss/tss.h
delete mode 100644 tools/verification/models/sched/sncid.dot
create mode 100644 tools/verification/models/sched/sts.dot
delete mode 100644 tools/verification/models/sched/tss.dot
diff --git a/Documentation/trace/rv/monitor_sched.rst b/Documentation/trace/rv/monitor_sched.rst
index 24b2c62a3bc26..6c4c00216c07a 100644
--- a/Documentation/trace/rv/monitor_sched.rst
+++ b/Documentation/trace/rv/monitor_sched.rst
@@ -40,26 +40,6 @@ defined in by Daniel Bristot in [1].
Currently we included the following:
-Monitor tss
-~~~~~~~~~~~
-
-The task switch while scheduling (tss) monitor ensures a task switch happens
-only in scheduling context, that is inside a call to `__schedule`::
-
- |
- |
- v
- +-----------------+
- | thread | <+
- +-----------------+ |
- | |
- | schedule_entry | schedule_exit
- v |
- sched_switch |
- +--------------- |
- | sched |
- +--------------> -+
-
Monitor sco
~~~~~~~~~~~
@@ -144,26 +124,55 @@ does not enable preemption::
|
scheduling_contex -+
-Monitor sncid
-~~~~~~~~~~~~~
-
-The schedule not called with interrupt disabled (sncid) monitor ensures
-schedule is not called with interrupt disabled::
+Monitor sts
+~~~~~~~~~~~
- |
- |
- v
- schedule_entry +--------------+
- schedule_exit | |
- +----------------- | can_sched |
- | | |
- +----------------> | | <+
- +--------------+ |
- | |
- | irq_disable | irq_enable
- v |
- |
- cant_sched -+
+The schedule implies task switch (sts) monitor ensures a task switch happens
+only in scheduling context and up to once, as well as scheduling occurs with
+interrupts enabled but no task switch can happen before interrupts are
+disabled. When the next task picked for execution is the same as the previously
+running one, no real task switch occurs but interrupts are disabled nonetheless::
+
+ irq_entry |
+ +----+ |
+ v | v
+ +------------+ irq_enable #===================# irq_disable
+ | | ------------> H H irq_entry
+ | cant_sched | <------------ H H irq_enable
+ | | irq_disable H can_sched H --------------+
+ +------------+ H H |
+ H H |
+ +---------------> H H <-------------+
+ | #===================#
+ | |
+ schedule_exit | schedule_entry
+ | v
+ | +-------------------+ irq_enable
+ | | scheduling | <---------------+
+ | +-------------------+ |
+ | | |
+ | | irq_disable +--------+ irq_entry
+ | v | | --------+
+ | +-------------------+ irq_entry | in_irq | |
+ | | | -----------> | | <-------+
+ | | disable_to_switch | +--------+
+ | | | --+
+ | +-------------------+ |
+ | | |
+ | | sched_switch |
+ | v |
+ | +-------------------+ |
+ | | switching | | irq_enable
+ | +-------------------+ |
+ | | |
+ | | irq_enable |
+ | v |
+ | +-------------------+ |
+ +-- | enable_to_exit | <-+
+ +-------------------+
+ ^ | irq_disable
+ | | irq_entry
+ +---------------+ irq_enable
References
----------
diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig
index 34164eb4ec913..b688b24081c8e 100644
--- a/kernel/trace/rv/Kconfig
+++ b/kernel/trace/rv/Kconfig
@@ -50,12 +50,11 @@ source "kernel/trace/rv/monitors/wip/Kconfig"
source "kernel/trace/rv/monitors/wwnr/Kconfig"
source "kernel/trace/rv/monitors/sched/Kconfig"
-source "kernel/trace/rv/monitors/tss/Kconfig"
source "kernel/trace/rv/monitors/sco/Kconfig"
source "kernel/trace/rv/monitors/snroc/Kconfig"
source "kernel/trace/rv/monitors/scpd/Kconfig"
source "kernel/trace/rv/monitors/snep/Kconfig"
-source "kernel/trace/rv/monitors/sncid/Kconfig"
+source "kernel/trace/rv/monitors/sts/Kconfig"
# Add new sched monitors here
source "kernel/trace/rv/monitors/rtapp/Kconfig"
diff --git a/kernel/trace/rv/Makefile b/kernel/trace/rv/Makefile
index 13ec2944c6650..1939d3d7621c6 100644
--- a/kernel/trace/rv/Makefile
+++ b/kernel/trace/rv/Makefile
@@ -6,15 +6,14 @@ obj-$(CONFIG_RV) += rv.o
obj-$(CONFIG_RV_MON_WIP) += monitors/wip/wip.o
obj-$(CONFIG_RV_MON_WWNR) += monitors/wwnr/wwnr.o
obj-$(CONFIG_RV_MON_SCHED) += monitors/sched/sched.o
-obj-$(CONFIG_RV_MON_TSS) += monitors/tss/tss.o
obj-$(CONFIG_RV_MON_SCO) += monitors/sco/sco.o
obj-$(CONFIG_RV_MON_SNROC) += monitors/snroc/snroc.o
obj-$(CONFIG_RV_MON_SCPD) += monitors/scpd/scpd.o
obj-$(CONFIG_RV_MON_SNEP) += monitors/snep/snep.o
-obj-$(CONFIG_RV_MON_SNCID) += monitors/sncid/sncid.o
obj-$(CONFIG_RV_MON_RTAPP) += monitors/rtapp/rtapp.o
obj-$(CONFIG_RV_MON_PAGEFAULT) += monitors/pagefault/pagefault.o
obj-$(CONFIG_RV_MON_SLEEP) += monitors/sleep/sleep.o
+obj-$(CONFIG_RV_MON_STS) += monitors/sts/sts.o
# Add new monitors here
obj-$(CONFIG_RV_REACTORS) += rv_reactors.o
obj-$(CONFIG_RV_REACT_PRINTK) += reactor_printk.o
diff --git a/kernel/trace/rv/monitors/sncid/Kconfig b/kernel/trace/rv/monitors/sncid/Kconfig
deleted file mode 100644
index 3a5639feaaaf6..0000000000000
--- a/kernel/trace/rv/monitors/sncid/Kconfig
+++ /dev/null
@@ -1,15 +0,0 @@
-# SPDX-License-Identifier: GPL-2.0-only
-#
-config RV_MON_SNCID
- depends on RV
- depends on TRACE_IRQFLAGS
- depends on RV_MON_SCHED
- default y
- select DA_MON_EVENTS_IMPLICIT
- bool "sncid monitor"
- help
- Monitor to ensure schedule is not called with interrupt disabled.
- This monitor is part of the sched monitors collection.
-
- For further information, see:
- Documentation/trace/rv/monitor_sched.rst
diff --git a/kernel/trace/rv/monitors/sncid/sncid.c b/kernel/trace/rv/monitors/sncid/sncid.c
deleted file mode 100644
index c8491f4263650..0000000000000
--- a/kernel/trace/rv/monitors/sncid/sncid.c
+++ /dev/null
@@ -1,95 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-#include <linux/ftrace.h>
-#include <linux/tracepoint.h>
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/init.h>
-#include <linux/rv.h>
-#include <rv/instrumentation.h>
-#include <rv/da_monitor.h>
-
-#define MODULE_NAME "sncid"
-
-#include <trace/events/sched.h>
-#include <trace/events/preemptirq.h>
-#include <rv_trace.h>
-#include <monitors/sched/sched.h>
-
-#include "sncid.h"
-
-static struct rv_monitor rv_sncid;
-DECLARE_DA_MON_PER_CPU(sncid, unsigned char);
-
-static void handle_irq_disable(void *data, unsigned long ip, unsigned long parent_ip)
-{
- da_handle_event_sncid(irq_disable_sncid);
-}
-
-static void handle_irq_enable(void *data, unsigned long ip, unsigned long parent_ip)
-{
- da_handle_start_event_sncid(irq_enable_sncid);
-}
-
-static void handle_schedule_entry(void *data, bool preempt)
-{
- da_handle_start_event_sncid(schedule_entry_sncid);
-}
-
-static void handle_schedule_exit(void *data, bool is_switch)
-{
- da_handle_start_event_sncid(schedule_exit_sncid);
-}
-
-static int enable_sncid(void)
-{
- int retval;
-
- retval = da_monitor_init_sncid();
- if (retval)
- return retval;
-
- rv_attach_trace_probe("sncid", irq_disable, handle_irq_disable);
- rv_attach_trace_probe("sncid", irq_enable, handle_irq_enable);
- rv_attach_trace_probe("sncid", sched_entry_tp, handle_schedule_entry);
- rv_attach_trace_probe("sncid", sched_exit_tp, handle_schedule_exit);
-
- return 0;
-}
-
-static void disable_sncid(void)
-{
- rv_sncid.enabled = 0;
-
- rv_detach_trace_probe("sncid", irq_disable, handle_irq_disable);
- rv_detach_trace_probe("sncid", irq_enable, handle_irq_enable);
- rv_detach_trace_probe("sncid", sched_entry_tp, handle_schedule_entry);
- rv_detach_trace_probe("sncid", sched_exit_tp, handle_schedule_exit);
-
- da_monitor_destroy_sncid();
-}
-
-static struct rv_monitor rv_sncid = {
- .name = "sncid",
- .description = "schedule not called with interrupt disabled.",
- .enable = enable_sncid,
- .disable = disable_sncid,
- .reset = da_monitor_reset_all_sncid,
- .enabled = 0,
-};
-
-static int __init register_sncid(void)
-{
- return rv_register_monitor(&rv_sncid, &rv_sched);
-}
-
-static void __exit unregister_sncid(void)
-{
- rv_unregister_monitor(&rv_sncid);
-}
-
-module_init(register_sncid);
-module_exit(unregister_sncid);
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Gabriele Monaco <gmonaco@redhat.com>");
-MODULE_DESCRIPTION("sncid: schedule not called with interrupt disabled.");
diff --git a/kernel/trace/rv/monitors/sncid/sncid.h b/kernel/trace/rv/monitors/sncid/sncid.h
deleted file mode 100644
index 21304725142bc..0000000000000
--- a/kernel/trace/rv/monitors/sncid/sncid.h
+++ /dev/null
@@ -1,49 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * Automatically generated C representation of sncid automaton
- * For further information about this format, see kernel documentation:
- * Documentation/trace/rv/deterministic_automata.rst
- */
-
-enum states_sncid {
- can_sched_sncid = 0,
- cant_sched_sncid,
- state_max_sncid
-};
-
-#define INVALID_STATE state_max_sncid
-
-enum events_sncid {
- irq_disable_sncid = 0,
- irq_enable_sncid,
- schedule_entry_sncid,
- schedule_exit_sncid,
- event_max_sncid
-};
-
-struct automaton_sncid {
- char *state_names[state_max_sncid];
- char *event_names[event_max_sncid];
- unsigned char function[state_max_sncid][event_max_sncid];
- unsigned char initial_state;
- bool final_states[state_max_sncid];
-};
-
-static const struct automaton_sncid automaton_sncid = {
- .state_names = {
- "can_sched",
- "cant_sched"
- },
- .event_names = {
- "irq_disable",
- "irq_enable",
- "schedule_entry",
- "schedule_exit"
- },
- .function = {
- { cant_sched_sncid, INVALID_STATE, can_sched_sncid, can_sched_sncid },
- { INVALID_STATE, can_sched_sncid, INVALID_STATE, INVALID_STATE },
- },
- .initial_state = can_sched_sncid,
- .final_states = { 1, 0 },
-};
diff --git a/kernel/trace/rv/monitors/sncid/sncid_trace.h b/kernel/trace/rv/monitors/sncid/sncid_trace.h
deleted file mode 100644
index 3ce42a57671d4..0000000000000
--- a/kernel/trace/rv/monitors/sncid/sncid_trace.h
+++ /dev/null
@@ -1,15 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-
-/*
- * Snippet to be included in rv_trace.h
- */
-
-#ifdef CONFIG_RV_MON_SNCID
-DEFINE_EVENT(event_da_monitor, event_sncid,
- TP_PROTO(char *state, char *event, char *next_state, bool final_state),
- TP_ARGS(state, event, next_state, final_state));
-
-DEFINE_EVENT(error_da_monitor, error_sncid,
- TP_PROTO(char *state, char *event),
- TP_ARGS(state, event));
-#endif /* CONFIG_RV_MON_SNCID */
diff --git a/kernel/trace/rv/monitors/sts/Kconfig b/kernel/trace/rv/monitors/sts/Kconfig
new file mode 100644
index 0000000000000..7d1ff0f6fc91e
--- /dev/null
+++ b/kernel/trace/rv/monitors/sts/Kconfig
@@ -0,0 +1,19 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+config RV_MON_STS
+ depends on RV
+ depends on TRACE_IRQFLAGS
+ depends on RV_MON_SCHED
+ default y
+ select DA_MON_EVENTS_IMPLICIT
+ bool "sts monitor"
+ help
+ Monitor to ensure relationships between scheduler and task switches
+ * the scheduler is called and returns with interrupts disabled
+ * each call to the scheduler has up to one switch
+ * switches only happen inside the scheduler
+ * each call to the scheduler disables interrupts to switch
+ This monitor is part of the sched monitors collection.
+
+ For further information, see:
+ Documentation/trace/rv/monitor_sched.rst
diff --git a/kernel/trace/rv/monitors/sts/sts.c b/kernel/trace/rv/monitors/sts/sts.c
new file mode 100644
index 0000000000000..c4a9cd67c1d21
--- /dev/null
+++ b/kernel/trace/rv/monitors/sts/sts.c
@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/ftrace.h>
+#include <linux/tracepoint.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/rv.h>
+#include <rv/instrumentation.h>
+#include <rv/da_monitor.h>
+
+#define MODULE_NAME "sts"
+
+#include <trace/events/sched.h>
+#include <trace/events/irq.h>
+#include <trace/events/preemptirq.h>
+#include <rv_trace.h>
+#include <monitors/sched/sched.h>
+
+#include "sts.h"
+
+static struct rv_monitor rv_sts;
+DECLARE_DA_MON_PER_CPU(sts, unsigned char);
+
+#ifdef CONFIG_X86_LOCAL_APIC
+#include <asm/trace/irq_vectors.h>
+
+static void handle_vector_irq_entry(void *data, int vector)
+{
+ da_handle_event_sts(irq_entry_sts);
+}
+
+static void attach_vector_irq(void)
+{
+ rv_attach_trace_probe("sts", local_timer_entry, handle_vector_irq_entry);
+ if (IS_ENABLED(CONFIG_IRQ_WORK))
+ rv_attach_trace_probe("sts", irq_work_entry, handle_vector_irq_entry);
+ if (IS_ENABLED(CONFIG_SMP)) {
+ rv_attach_trace_probe("sts", reschedule_entry, handle_vector_irq_entry);
+ rv_attach_trace_probe("sts", call_function_entry, handle_vector_irq_entry);
+ rv_attach_trace_probe("sts", call_function_single_entry, handle_vector_irq_entry);
+ }
+}
+
+static void detach_vector_irq(void)
+{
+ rv_detach_trace_probe("sts", local_timer_entry, handle_vector_irq_entry);
+ if (IS_ENABLED(CONFIG_IRQ_WORK))
+ rv_detach_trace_probe("sts", irq_work_entry, handle_vector_irq_entry);
+ if (IS_ENABLED(CONFIG_SMP)) {
+ rv_detach_trace_probe("sts", reschedule_entry, handle_vector_irq_entry);
+ rv_detach_trace_probe("sts", call_function_entry, handle_vector_irq_entry);
+ rv_detach_trace_probe("sts", call_function_single_entry, handle_vector_irq_entry);
+ }
+}
+
+#else
+/* We assume irq_entry tracepoints are sufficient on other architectures */
+static void attach_vector_irq(void) { }
+static void detach_vector_irq(void) { }
+#endif
+
+static void handle_irq_disable(void *data, unsigned long ip, unsigned long parent_ip)
+{
+ da_handle_event_sts(irq_disable_sts);
+}
+
+static void handle_irq_enable(void *data, unsigned long ip, unsigned long parent_ip)
+{
+ da_handle_event_sts(irq_enable_sts);
+}
+
+static void handle_irq_entry(void *data, int irq, struct irqaction *action)
+{
+ da_handle_event_sts(irq_entry_sts);
+}
+
+static void handle_sched_switch(void *data, bool preempt,
+ struct task_struct *prev,
+ struct task_struct *next,
+ unsigned int prev_state)
+{
+ da_handle_event_sts(sched_switch_sts);
+}
+
+static void handle_schedule_entry(void *data, bool preempt)
+{
+ da_handle_event_sts(schedule_entry_sts);
+}
+
+static void handle_schedule_exit(void *data, bool is_switch)
+{
+ da_handle_start_event_sts(schedule_exit_sts);
+}
+
+static int enable_sts(void)
+{
+ int retval;
+
+ retval = da_monitor_init_sts();
+ if (retval)
+ return retval;
+
+ rv_attach_trace_probe("sts", irq_disable, handle_irq_disable);
+ rv_attach_trace_probe("sts", irq_enable, handle_irq_enable);
+ rv_attach_trace_probe("sts", irq_handler_entry, handle_irq_entry);
+ rv_attach_trace_probe("sts", sched_switch, handle_sched_switch);
+ rv_attach_trace_probe("sts", sched_entry_tp, handle_schedule_entry);
+ rv_attach_trace_probe("sts", sched_exit_tp, handle_schedule_exit);
+ attach_vector_irq();
+
+ return 0;
+}
+
+static void disable_sts(void)
+{
+ rv_sts.enabled = 0;
+
+ rv_detach_trace_probe("sts", irq_disable, handle_irq_disable);
+ rv_detach_trace_probe("sts", irq_enable, handle_irq_enable);
+ rv_detach_trace_probe("sts", irq_handler_entry, handle_irq_entry);
+ rv_detach_trace_probe("sts", sched_switch, handle_sched_switch);
+ rv_detach_trace_probe("sts", sched_entry_tp, handle_schedule_entry);
+ rv_detach_trace_probe("sts", sched_exit_tp, handle_schedule_exit);
+ detach_vector_irq();
+
+ da_monitor_destroy_sts();
+}
+
+/*
+ * This is the monitor register section.
+ */
+static struct rv_monitor rv_sts = {
+ .name = "sts",
+ .description = "schedule implies task switch.",
+ .enable = enable_sts,
+ .disable = disable_sts,
+ .reset = da_monitor_reset_all_sts,
+ .enabled = 0,
+};
+
+static int __init register_sts(void)
+{
+ return rv_register_monitor(&rv_sts, &rv_sched);
+}
+
+static void __exit unregister_sts(void)
+{
+ rv_unregister_monitor(&rv_sts);
+}
+
+module_init(register_sts);
+module_exit(unregister_sts);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Gabriele Monaco <gmonaco@redhat.com>");
+MODULE_DESCRIPTION("sts: schedule implies task switch.");
diff --git a/kernel/trace/rv/monitors/sts/sts.h b/kernel/trace/rv/monitors/sts/sts.h
new file mode 100644
index 0000000000000..3368b6599a005
--- /dev/null
+++ b/kernel/trace/rv/monitors/sts/sts.h
@@ -0,0 +1,117 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Automatically generated C representation of sts automaton
+ * For further information about this format, see kernel documentation:
+ * Documentation/trace/rv/deterministic_automata.rst
+ */
+
+enum states_sts {
+ can_sched_sts = 0,
+ cant_sched_sts,
+ disable_to_switch_sts,
+ enable_to_exit_sts,
+ in_irq_sts,
+ scheduling_sts,
+ switching_sts,
+ state_max_sts
+};
+
+#define INVALID_STATE state_max_sts
+
+enum events_sts {
+ irq_disable_sts = 0,
+ irq_enable_sts,
+ irq_entry_sts,
+ sched_switch_sts,
+ schedule_entry_sts,
+ schedule_exit_sts,
+ event_max_sts
+};
+
+struct automaton_sts {
+ char *state_names[state_max_sts];
+ char *event_names[event_max_sts];
+ unsigned char function[state_max_sts][event_max_sts];
+ unsigned char initial_state;
+ bool final_states[state_max_sts];
+};
+
+static const struct automaton_sts automaton_sts = {
+ .state_names = {
+ "can_sched",
+ "cant_sched",
+ "disable_to_switch",
+ "enable_to_exit",
+ "in_irq",
+ "scheduling",
+ "switching"
+ },
+ .event_names = {
+ "irq_disable",
+ "irq_enable",
+ "irq_entry",
+ "sched_switch",
+ "schedule_entry",
+ "schedule_exit"
+ },
+ .function = {
+ {
+ cant_sched_sts,
+ INVALID_STATE,
+ INVALID_STATE,
+ INVALID_STATE,
+ scheduling_sts,
+ INVALID_STATE
+ },
+ {
+ INVALID_STATE,
+ can_sched_sts,
+ cant_sched_sts,
+ INVALID_STATE,
+ INVALID_STATE,
+ INVALID_STATE
+ },
+ {
+ INVALID_STATE,
+ enable_to_exit_sts,
+ in_irq_sts,
+ switching_sts,
+ INVALID_STATE,
+ INVALID_STATE
+ },
+ {
+ enable_to_exit_sts,
+ enable_to_exit_sts,
+ enable_to_exit_sts,
+ INVALID_STATE,
+ INVALID_STATE,
+ can_sched_sts
+ },
+ {
+ INVALID_STATE,
+ scheduling_sts,
+ in_irq_sts,
+ INVALID_STATE,
+ INVALID_STATE,
+ INVALID_STATE
+ },
+ {
+ disable_to_switch_sts,
+ INVALID_STATE,
+ INVALID_STATE,
+ INVALID_STATE,
+ INVALID_STATE,
+ INVALID_STATE
+ },
+ {
+ INVALID_STATE,
+ enable_to_exit_sts,
+ INVALID_STATE,
+ INVALID_STATE,
+ INVALID_STATE,
+ INVALID_STATE
+ },
+ },
+ .initial_state = can_sched_sts,
+ .final_states = { 1, 0, 0, 0, 0, 0, 0 },
+};
diff --git a/kernel/trace/rv/monitors/tss/tss_trace.h b/kernel/trace/rv/monitors/sts/sts_trace.h
similarity index 67%
rename from kernel/trace/rv/monitors/tss/tss_trace.h
rename to kernel/trace/rv/monitors/sts/sts_trace.h
index 4619dbb50cc06..d78beb58d5b3d 100644
--- a/kernel/trace/rv/monitors/tss/tss_trace.h
+++ b/kernel/trace/rv/monitors/sts/sts_trace.h
@@ -4,12 +4,12 @@
* Snippet to be included in rv_trace.h
*/
-#ifdef CONFIG_RV_MON_TSS
-DEFINE_EVENT(event_da_monitor, event_tss,
+#ifdef CONFIG_RV_MON_STS
+DEFINE_EVENT(event_da_monitor, event_sts,
TP_PROTO(char *state, char *event, char *next_state, bool final_state),
TP_ARGS(state, event, next_state, final_state));
-DEFINE_EVENT(error_da_monitor, error_tss,
+DEFINE_EVENT(error_da_monitor, error_sts,
TP_PROTO(char *state, char *event),
TP_ARGS(state, event));
-#endif /* CONFIG_RV_MON_TSS */
+#endif /* CONFIG_RV_MON_STS */
diff --git a/kernel/trace/rv/monitors/tss/Kconfig b/kernel/trace/rv/monitors/tss/Kconfig
deleted file mode 100644
index 479f86f52e60d..0000000000000
--- a/kernel/trace/rv/monitors/tss/Kconfig
+++ /dev/null
@@ -1,14 +0,0 @@
-# SPDX-License-Identifier: GPL-2.0-only
-#
-config RV_MON_TSS
- depends on RV
- depends on RV_MON_SCHED
- default y
- select DA_MON_EVENTS_IMPLICIT
- bool "tss monitor"
- help
- Monitor to ensure sched_switch happens only in scheduling context.
- This monitor is part of the sched monitors collection.
-
- For further information, see:
- Documentation/trace/rv/monitor_sched.rst
diff --git a/kernel/trace/rv/monitors/tss/tss.c b/kernel/trace/rv/monitors/tss/tss.c
deleted file mode 100644
index 95ebd15131f52..0000000000000
--- a/kernel/trace/rv/monitors/tss/tss.c
+++ /dev/null
@@ -1,90 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-#include <linux/ftrace.h>
-#include <linux/tracepoint.h>
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/init.h>
-#include <linux/rv.h>
-#include <rv/instrumentation.h>
-#include <rv/da_monitor.h>
-
-#define MODULE_NAME "tss"
-
-#include <trace/events/sched.h>
-#include <rv_trace.h>
-#include <monitors/sched/sched.h>
-
-#include "tss.h"
-
-static struct rv_monitor rv_tss;
-DECLARE_DA_MON_PER_CPU(tss, unsigned char);
-
-static void handle_sched_switch(void *data, bool preempt,
- struct task_struct *prev,
- struct task_struct *next,
- unsigned int prev_state)
-{
- da_handle_event_tss(sched_switch_tss);
-}
-
-static void handle_schedule_entry(void *data, bool preempt)
-{
- da_handle_event_tss(schedule_entry_tss);
-}
-
-static void handle_schedule_exit(void *data, bool is_switch)
-{
- da_handle_start_event_tss(schedule_exit_tss);
-}
-
-static int enable_tss(void)
-{
- int retval;
-
- retval = da_monitor_init_tss();
- if (retval)
- return retval;
-
- rv_attach_trace_probe("tss", sched_switch, handle_sched_switch);
- rv_attach_trace_probe("tss", sched_entry_tp, handle_schedule_entry);
- rv_attach_trace_probe("tss", sched_exit_tp, handle_schedule_exit);
-
- return 0;
-}
-
-static void disable_tss(void)
-{
- rv_tss.enabled = 0;
-
- rv_detach_trace_probe("tss", sched_switch, handle_sched_switch);
- rv_detach_trace_probe("tss", sched_entry_tp, handle_schedule_entry);
- rv_detach_trace_probe("tss", sched_exit_tp, handle_schedule_exit);
-
- da_monitor_destroy_tss();
-}
-
-static struct rv_monitor rv_tss = {
- .name = "tss",
- .description = "task switch while scheduling.",
- .enable = enable_tss,
- .disable = disable_tss,
- .reset = da_monitor_reset_all_tss,
- .enabled = 0,
-};
-
-static int __init register_tss(void)
-{
- return rv_register_monitor(&rv_tss, &rv_sched);
-}
-
-static void __exit unregister_tss(void)
-{
- rv_unregister_monitor(&rv_tss);
-}
-
-module_init(register_tss);
-module_exit(unregister_tss);
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Gabriele Monaco <gmonaco@redhat.com>");
-MODULE_DESCRIPTION("tss: task switch while scheduling.");
diff --git a/kernel/trace/rv/monitors/tss/tss.h b/kernel/trace/rv/monitors/tss/tss.h
deleted file mode 100644
index f0a36fda1b873..0000000000000
--- a/kernel/trace/rv/monitors/tss/tss.h
+++ /dev/null
@@ -1,47 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * Automatically generated C representation of tss automaton
- * For further information about this format, see kernel documentation:
- * Documentation/trace/rv/deterministic_automata.rst
- */
-
-enum states_tss {
- thread_tss = 0,
- sched_tss,
- state_max_tss
-};
-
-#define INVALID_STATE state_max_tss
-
-enum events_tss {
- sched_switch_tss = 0,
- schedule_entry_tss,
- schedule_exit_tss,
- event_max_tss
-};
-
-struct automaton_tss {
- char *state_names[state_max_tss];
- char *event_names[event_max_tss];
- unsigned char function[state_max_tss][event_max_tss];
- unsigned char initial_state;
- bool final_states[state_max_tss];
-};
-
-static const struct automaton_tss automaton_tss = {
- .state_names = {
- "thread",
- "sched"
- },
- .event_names = {
- "sched_switch",
- "schedule_entry",
- "schedule_exit"
- },
- .function = {
- { INVALID_STATE, sched_tss, INVALID_STATE },
- { sched_tss, INVALID_STATE, thread_tss },
- },
- .initial_state = thread_tss,
- .final_states = { 1, 0 },
-};
diff --git a/kernel/trace/rv/rv_trace.h b/kernel/trace/rv/rv_trace.h
index 044772515256a..fa9613cb94699 100644
--- a/kernel/trace/rv/rv_trace.h
+++ b/kernel/trace/rv/rv_trace.h
@@ -58,11 +58,10 @@ DECLARE_EVENT_CLASS(error_da_monitor,
);
#include <monitors/wip/wip_trace.h>
-#include <monitors/tss/tss_trace.h>
#include <monitors/sco/sco_trace.h>
#include <monitors/scpd/scpd_trace.h>
#include <monitors/snep/snep_trace.h>
-#include <monitors/sncid/sncid_trace.h>
+#include <monitors/sts/sts_trace.h>
// Add new monitors based on CONFIG_DA_MON_EVENTS_IMPLICIT here
#endif /* CONFIG_DA_MON_EVENTS_IMPLICIT */
diff --git a/tools/verification/models/sched/sncid.dot b/tools/verification/models/sched/sncid.dot
deleted file mode 100644
index 072851721b50a..0000000000000
--- a/tools/verification/models/sched/sncid.dot
+++ /dev/null
@@ -1,18 +0,0 @@
-digraph state_automaton {
- center = true;
- size = "7,11";
- {node [shape = plaintext, style=invis, label=""] "__init_can_sched"};
- {node [shape = ellipse] "can_sched"};
- {node [shape = plaintext] "can_sched"};
- {node [shape = plaintext] "cant_sched"};
- "__init_can_sched" -> "can_sched";
- "can_sched" [label = "can_sched", color = green3];
- "can_sched" -> "can_sched" [ label = "schedule_entry\nschedule_exit" ];
- "can_sched" -> "cant_sched" [ label = "irq_disable" ];
- "cant_sched" [label = "cant_sched"];
- "cant_sched" -> "can_sched" [ label = "irq_enable" ];
- { rank = min ;
- "__init_can_sched";
- "can_sched";
- }
-}
diff --git a/tools/verification/models/sched/sts.dot b/tools/verification/models/sched/sts.dot
new file mode 100644
index 0000000000000..8f5f38be04d54
--- /dev/null
+++ b/tools/verification/models/sched/sts.dot
@@ -0,0 +1,38 @@
+digraph state_automaton {
+ center = true;
+ size = "7,11";
+ {node [shape = plaintext, style=invis, label=""] "__init_can_sched"};
+ {node [shape = doublecircle] "can_sched"};
+ {node [shape = circle] "can_sched"};
+ {node [shape = circle] "cant_sched"};
+ {node [shape = circle] "disable_to_switch"};
+ {node [shape = circle] "enable_to_exit"};
+ {node [shape = circle] "in_irq"};
+ {node [shape = circle] "scheduling"};
+ {node [shape = circle] "switching"};
+ "__init_can_sched" -> "can_sched";
+ "can_sched" [label = "can_sched", color = green3];
+ "can_sched" -> "cant_sched" [ label = "irq_disable" ];
+ "can_sched" -> "scheduling" [ label = "schedule_entry" ];
+ "cant_sched" [label = "cant_sched"];
+ "cant_sched" -> "can_sched" [ label = "irq_enable" ];
+ "cant_sched" -> "cant_sched" [ label = "irq_entry" ];
+ "disable_to_switch" [label = "disable_to_switch"];
+ "disable_to_switch" -> "enable_to_exit" [ label = "irq_enable" ];
+ "disable_to_switch" -> "in_irq" [ label = "irq_entry" ];
+ "disable_to_switch" -> "switching" [ label = "sched_switch" ];
+ "enable_to_exit" [label = "enable_to_exit"];
+ "enable_to_exit" -> "can_sched" [ label = "schedule_exit" ];
+ "enable_to_exit" -> "enable_to_exit" [ label = "irq_disable\nirq_entry\nirq_enable" ];
+ "in_irq" [label = "in_irq"];
+ "in_irq" -> "in_irq" [ label = "irq_entry" ];
+ "in_irq" -> "scheduling" [ label = "irq_enable" ];
+ "scheduling" [label = "scheduling"];
+ "scheduling" -> "disable_to_switch" [ label = "irq_disable" ];
+ "switching" [label = "switching"];
+ "switching" -> "enable_to_exit" [ label = "irq_enable" ];
+ { rank = min ;
+ "__init_can_sched";
+ "can_sched";
+ }
+}
diff --git a/tools/verification/models/sched/tss.dot b/tools/verification/models/sched/tss.dot
deleted file mode 100644
index 7dfa1d9121bbd..0000000000000
--- a/tools/verification/models/sched/tss.dot
+++ /dev/null
@@ -1,18 +0,0 @@
-digraph state_automaton {
- center = true;
- size = "7,11";
- {node [shape = plaintext] "sched"};
- {node [shape = plaintext, style=invis, label=""] "__init_thread"};
- {node [shape = ellipse] "thread"};
- {node [shape = plaintext] "thread"};
- "__init_thread" -> "thread";
- "sched" [label = "sched"];
- "sched" -> "sched" [ label = "sched_switch" ];
- "sched" -> "thread" [ label = "schedule_exit" ];
- "thread" [label = "thread", color = green3];
- "thread" -> "sched" [ label = "schedule_entry" ];
- { rank = min ;
- "__init_thread";
- "thread";
- }
-}
--
2.50.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH v4 12/14] rv: Replace tss and sncid monitors with more complete sts
2025-07-21 8:23 ` [PATCH v4 12/14] rv: Replace tss and sncid monitors with more complete sts Gabriele Monaco
@ 2025-07-21 15:15 ` Nam Cao
2025-07-21 16:13 ` Gabriele Monaco
0 siblings, 1 reply; 5+ messages in thread
From: Nam Cao @ 2025-07-21 15:15 UTC (permalink / raw)
To: Gabriele Monaco
Cc: linux-kernel, Steven Rostedt, Jonathan Corbet, Masami Hiramatsu,
linux-trace-kernel, linux-doc, Ingo Molnar, Peter Zijlstra,
Tomas Glozar, Juri Lelli, Clark Williams, John Kacur
On Mon, Jul 21, 2025 at 10:23:22AM +0200, Gabriele Monaco wrote:
> The tss monitor currently guarantees task switches can happen only while
> scheduling, whereas the sncid monitor enforces scheduling occurs with
> interrupt disabled.
>
> Replace the monitors with a more comprehensive specification which
> implies both but also ensures that:
> * each scheduler call disable interrupts to switch
> * each task switch happens with interrupts disabled
>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
>
> fixup sts remove sncid
Is this here by accident?
I cannot comment on the model. The CONFIG_X86_LOCAL_APIC case looks
complex, but I cannot comment on that either.
But things look fine from RV perspective, so:
Acked-by: Nam Cao <namcao@linutronix.de>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v4 12/14] rv: Replace tss and sncid monitors with more complete sts
2025-07-21 15:15 ` Nam Cao
@ 2025-07-21 16:13 ` Gabriele Monaco
0 siblings, 0 replies; 5+ messages in thread
From: Gabriele Monaco @ 2025-07-21 16:13 UTC (permalink / raw)
To: Nam Cao
Cc: linux-kernel, Steven Rostedt, Jonathan Corbet, Masami Hiramatsu,
linux-trace-kernel, linux-doc, Ingo Molnar, Peter Zijlstra,
Tomas Glozar, Juri Lelli, Clark Williams, John Kacur
On Mon, 2025-07-21 at 17:15 +0200, Nam Cao wrote:
> On Mon, Jul 21, 2025 at 10:23:22AM +0200, Gabriele Monaco wrote:
> > The tss monitor currently guarantees task switches can happen only
> > while
> > scheduling, whereas the sncid monitor enforces scheduling occurs
> > with
> > interrupt disabled.
> >
> > Replace the monitors with a more comprehensive specification which
> > implies both but also ensures that:
> > * each scheduler call disable interrupts to switch
> > * each task switch happens with interrupts disabled
> >
> > Cc: Ingo Molnar <mingo@redhat.com>
> > Cc: Peter Zijlstra <peterz@infradead.org>
> >
> > fixup sts remove sncid
>
> Is this here by accident?
>
Damn, again.. thanks for spotting.
> I cannot comment on the model. The CONFIG_X86_LOCAL_APIC case looks
> complex, but I cannot comment on that either.
Do you mean the amount of tracepoints or the state in the monitor?
As far as I'm aware some special IRQs on x86 use those tracepoints, and
I needed to use all of them not to miss real interrupts, which I need
to understand if interrupts where disabled programmatically or by a
hardware IRQ.
>
> But things look fine from RV perspective, so:
> Acked-by: Nam Cao <namcao@linutronix.de>
Thanks!
Gabriele
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v4 13/14] rv: Add nrp and sssw per-task monitors
[not found] <20250721082325.71554-1-gmonaco@redhat.com>
2025-07-21 8:23 ` [PATCH v4 12/14] rv: Replace tss and sncid monitors with more complete sts Gabriele Monaco
@ 2025-07-21 8:23 ` Gabriele Monaco
2025-07-21 8:23 ` [PATCH v4 14/14] rv: Add opid per-cpu monitor Gabriele Monaco
2 siblings, 0 replies; 5+ messages in thread
From: Gabriele Monaco @ 2025-07-21 8:23 UTC (permalink / raw)
To: linux-kernel, Steven Rostedt, Jonathan Corbet, Masami Hiramatsu,
linux-trace-kernel, linux-doc
Cc: Gabriele Monaco, Ingo Molnar, Peter Zijlstra, Nam Cao,
Tomas Glozar, Juri Lelli, Clark Williams, John Kacur
Add 2 per-task monitors as part of the sched model:
* nrp: need-resched preempts
Monitor to ensure preemption requires need resched.
* sssw: set state sleep and wakeup
Monitor to ensure sched_set_state to sleepable leads to sleeping and
sleeping tasks require wakeup.
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
---
Documentation/trace/rv/monitor_sched.rst | 167 +++++++++++++++++++++
kernel/trace/rv/Kconfig | 2 +
kernel/trace/rv/Makefile | 2 +
kernel/trace/rv/monitors/nrp/Kconfig | 16 ++
kernel/trace/rv/monitors/nrp/nrp.c | 138 +++++++++++++++++
kernel/trace/rv/monitors/nrp/nrp.h | 75 +++++++++
kernel/trace/rv/monitors/nrp/nrp_trace.h | 15 ++
kernel/trace/rv/monitors/sched/Kconfig | 1 +
kernel/trace/rv/monitors/sssw/Kconfig | 15 ++
kernel/trace/rv/monitors/sssw/sssw.c | 116 ++++++++++++++
kernel/trace/rv/monitors/sssw/sssw.h | 105 +++++++++++++
kernel/trace/rv/monitors/sssw/sssw_trace.h | 15 ++
kernel/trace/rv/rv_trace.h | 2 +
tools/verification/models/sched/nrp.dot | 29 ++++
tools/verification/models/sched/sssw.dot | 30 ++++
15 files changed, 728 insertions(+)
create mode 100644 kernel/trace/rv/monitors/nrp/Kconfig
create mode 100644 kernel/trace/rv/monitors/nrp/nrp.c
create mode 100644 kernel/trace/rv/monitors/nrp/nrp.h
create mode 100644 kernel/trace/rv/monitors/nrp/nrp_trace.h
create mode 100644 kernel/trace/rv/monitors/sssw/Kconfig
create mode 100644 kernel/trace/rv/monitors/sssw/sssw.c
create mode 100644 kernel/trace/rv/monitors/sssw/sssw.h
create mode 100644 kernel/trace/rv/monitors/sssw/sssw_trace.h
create mode 100644 tools/verification/models/sched/nrp.dot
create mode 100644 tools/verification/models/sched/sssw.dot
diff --git a/Documentation/trace/rv/monitor_sched.rst b/Documentation/trace/rv/monitor_sched.rst
index 6c4c00216c07a..11ef963cb5780 100644
--- a/Documentation/trace/rv/monitor_sched.rst
+++ b/Documentation/trace/rv/monitor_sched.rst
@@ -174,6 +174,173 @@ running one, no real task switch occurs but interrupts are disabled nonetheless:
| | irq_entry
+---------------+ irq_enable
+Monitor nrp
+-----------
+
+The need resched preempts (nrp) monitor ensures preemption requires
+``need_resched``. Only kernel preemption is considered, since preemption
+while returning to userspace, for this monitor, is indistinguishable from
+``sched_switch_yield`` (described in the sssw monitor).
+A kernel preemption is whenever ``__schedule`` is called with the preemption
+flag set to true (e.g. from preempt_enable or exiting from interrupts). This
+type of preemption occurs after the need for ``rescheduling`` has been set.
+This is not valid for the *lazy* variant of the flag, which causes only
+userspace preemption.
+A ``schedule_entry_preempt`` may involve a task switch or not, in the latter
+case, a task goes through the scheduler from a preemption context but it is
+picked as the next task to run. Since the scheduler runs, this clears the need
+to reschedule. The ``any_thread_running`` state does not imply the monitored
+task is not running as this monitor does not track the outcome of scheduling.
+
+In theory, a preemption can only occur after the ``need_resched`` flag is set. In
+practice, however, it is possible to see a preemption where the flag is not
+set. This can happen in one specific condition::
+
+ need_resched
+ preempt_schedule()
+ preempt_schedule_irq()
+ __schedule()
+ !need_resched
+ __schedule()
+
+In the situation above, standard preemption starts (e.g. from preempt_enable
+when the flag is set), an interrupt occurs before scheduling and, on its exit
+path, it schedules, which clears the ``need_resched`` flag.
+When the preempted task runs again, the standard preemption started earlier
+resumes, although the flag is no longer set. The monitor considers this a
+``nested_preemption``, this allows another preemption without re-setting the
+flag. This condition relaxes the monitor constraints and may catch false
+negatives (i.e. no real ``nested_preemptions``) but makes the monitor more
+robust and able to validate other scenarios.
+For simplicity, the monitor starts in ``preempt_irq``, although no interrupt
+occurred, as the situation above is hard to pinpoint::
+
+ schedule_entry
+ irq_entry #===========================================#
+ +-------------------------- H H
+ | H H
+ +-------------------------> H any_thread_running H
+ H H
+ +-------------------------> H H
+ | #===========================================#
+ | schedule_entry | ^
+ | schedule_entry_preempt | sched_need_resched | schedule_entry
+ | | schedule_entry_preempt
+ | v |
+ | +----------------------+ |
+ | +--- | | |
+ | sched_need_resched | | rescheduling | -+
+ | +--> | |
+ | +----------------------+
+ | | irq_entry
+ | v
+ | +----------------------+
+ | | | ---+
+ | ---> | | | sched_need_resched
+ | | preempt_irq | | irq_entry
+ | | | <--+
+ | | | <--+
+ | +----------------------+ |
+ | | schedule_entry | sched_need_resched
+ | | schedule_entry_preempt |
+ | v |
+ | +-----------------------+ |
+ +-------------------------- | nested_preempt | --+
+ +-----------------------+
+ ^ irq_entry |
+ +-------------------+
+
+Due to how the ``need_resched`` flag on the preemption count works on arm64,
+this monitor is unstable on that architecture, as it often records preemption
+when the flag is not set, even in presence of the workaround above.
+For the time being, the monitor is disabled by default on arm64.
+
+Monitor sssw
+------------
+
+The set state sleep and wakeup (sssw) monitor ensures ``set_state`` to
+sleepable leads to sleeping and sleeping tasks require wakeup. It includes the
+following types of switch:
+
+* ``switch_suspend``:
+ a task puts itself to sleep, this can happen only after explicitly setting
+ the task to ``sleepable``. After a task is suspended, it needs to be woken up
+ (``waking`` state) before being switched in again.
+ Setting the task's state to ``sleepable`` can be reverted before switching if it
+ is woken up or set to ``runnable``.
+* ``switch_blocking``:
+ a special case of a ``switch_suspend`` where the task is waiting on a
+ sleeping RT lock (``PREEMPT_RT`` only), it is common to see wakeup and set
+ state events racing with each other and this leads the model to perceive this
+ type of switch when the task is not set to sleepable. This is a limitation of
+ the model in SMP system and workarounds may slow down the system.
+* ``switch_preempt``:
+ a task switch as a result of kernel preemption (``schedule_entry_preempt`` in
+ the nrp model).
+* ``switch_yield``:
+ a task explicitly calls the scheduler or is preempted while returning to
+ userspace. It can happen after a ``yield`` system call, from the idle task or
+ if the ``need_resched`` flag is set. By definition, a task cannot yield while
+ ``sleepable`` as that would be a suspension. A special case of a yield occurs
+ when a task in ``TASK_INTERRUPTIBLE`` calls the scheduler while a signal is
+ pending. The task doesn't go through the usual blocking/waking and is set
+ back to runnable, the resulting switch (if there) looks like a yield to the
+ ``signal_wakeup`` state and is followed by the signal delivery. From this
+ state, the monitor expects a signal even if it sees a wakeup event, although
+ not necessary, to rule out false negatives.
+
+This monitor doesn't include a running state, ``sleepable`` and ``runnable``
+are only referring to the task's desired state, which could be scheduled out
+(e.g. due to preemption). However, it does include the event
+``sched_switch_in`` to represent when a task is allowed to become running. This
+can be triggered also by preemption, but cannot occur after the task got to
+``sleeping`` before a ``wakeup`` occurs::
+
+ +--------------------------------------------------------------------------+
+ | |
+ | |
+ | switch_suspend | |
+ | switch_blocking | |
+ v v |
+ +----------+ #==========================# set_state_runnable |
+ | | H H wakeup |
+ | | H H switch_in |
+ | | H H switch_yield |
+ | sleeping | H H switch_preempt |
+ | | H H signal_deliver |
+ | | switch_ H H ------+ |
+ | | _blocking H runnable H | |
+ | | <----------- H H <-----+ |
+ +----------+ H H |
+ | wakeup H H |
+ +---------------------> H H |
+ H H |
+ +---------> H H |
+ | #==========================# |
+ | | ^ |
+ | | | set_state_runnable |
+ | | | wakeup |
+ | set_state_sleepable | +------------------------+
+ | v | |
+ | +--------------------------+ set_state_sleepable
+ | | | switch_in
+ | | | switch_preempt
+ signal_deliver | sleepable | signal_deliver
+ | | | ------+
+ | | | |
+ | | | <-----+
+ | +--------------------------+
+ | | ^
+ | switch_yield | set_state_sleepable
+ | v |
+ | +---------------+ |
+ +---------- | signal_wakeup | -+
+ +---------------+
+ ^ | switch_in
+ | | switch_preempt
+ | | switch_yield
+ +-----------+ wakeup
+
References
----------
diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig
index b688b24081c8e..59d0db898d4ab 100644
--- a/kernel/trace/rv/Kconfig
+++ b/kernel/trace/rv/Kconfig
@@ -55,6 +55,8 @@ source "kernel/trace/rv/monitors/snroc/Kconfig"
source "kernel/trace/rv/monitors/scpd/Kconfig"
source "kernel/trace/rv/monitors/snep/Kconfig"
source "kernel/trace/rv/monitors/sts/Kconfig"
+source "kernel/trace/rv/monitors/nrp/Kconfig"
+source "kernel/trace/rv/monitors/sssw/Kconfig"
# Add new sched monitors here
source "kernel/trace/rv/monitors/rtapp/Kconfig"
diff --git a/kernel/trace/rv/Makefile b/kernel/trace/rv/Makefile
index 1939d3d7621c6..2afac88539d3f 100644
--- a/kernel/trace/rv/Makefile
+++ b/kernel/trace/rv/Makefile
@@ -14,6 +14,8 @@ obj-$(CONFIG_RV_MON_RTAPP) += monitors/rtapp/rtapp.o
obj-$(CONFIG_RV_MON_PAGEFAULT) += monitors/pagefault/pagefault.o
obj-$(CONFIG_RV_MON_SLEEP) += monitors/sleep/sleep.o
obj-$(CONFIG_RV_MON_STS) += monitors/sts/sts.o
+obj-$(CONFIG_RV_MON_NRP) += monitors/nrp/nrp.o
+obj-$(CONFIG_RV_MON_SSSW) += monitors/sssw/sssw.o
# Add new monitors here
obj-$(CONFIG_RV_REACTORS) += rv_reactors.o
obj-$(CONFIG_RV_REACT_PRINTK) += reactor_printk.o
diff --git a/kernel/trace/rv/monitors/nrp/Kconfig b/kernel/trace/rv/monitors/nrp/Kconfig
new file mode 100644
index 0000000000000..f5ec08f65535d
--- /dev/null
+++ b/kernel/trace/rv/monitors/nrp/Kconfig
@@ -0,0 +1,16 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+config RV_MON_NRP
+ depends on RV
+ depends on RV_MON_SCHED
+ default y if !ARM64
+ select DA_MON_EVENTS_ID
+ bool "nrp monitor"
+ help
+ Monitor to ensure preemption requires need resched.
+ This monitor is part of the sched monitors collection.
+
+ This monitor is unstable on arm64, say N unless you are testing it.
+
+ For further information, see:
+ Documentation/trace/rv/monitor_sched.rst
diff --git a/kernel/trace/rv/monitors/nrp/nrp.c b/kernel/trace/rv/monitors/nrp/nrp.c
new file mode 100644
index 0000000000000..5a83b71714329
--- /dev/null
+++ b/kernel/trace/rv/monitors/nrp/nrp.c
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/ftrace.h>
+#include <linux/tracepoint.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/rv.h>
+#include <rv/instrumentation.h>
+#include <rv/da_monitor.h>
+
+#define MODULE_NAME "nrp"
+
+#include <trace/events/irq.h>
+#include <trace/events/sched.h>
+#include <rv_trace.h>
+#include <monitors/sched/sched.h>
+
+#include "nrp.h"
+
+static struct rv_monitor rv_nrp;
+DECLARE_DA_MON_PER_TASK(nrp, unsigned char);
+
+#ifdef CONFIG_X86_LOCAL_APIC
+#include <asm/trace/irq_vectors.h>
+
+static void handle_vector_irq_entry(void *data, int vector)
+{
+ da_handle_event_nrp(current, irq_entry_nrp);
+}
+
+static void attach_vector_irq(void)
+{
+ rv_attach_trace_probe("nrp", local_timer_entry, handle_vector_irq_entry);
+ if (IS_ENABLED(CONFIG_IRQ_WORK))
+ rv_attach_trace_probe("nrp", irq_work_entry, handle_vector_irq_entry);
+ if (IS_ENABLED(CONFIG_SMP)) {
+ rv_attach_trace_probe("nrp", reschedule_entry, handle_vector_irq_entry);
+ rv_attach_trace_probe("nrp", call_function_entry, handle_vector_irq_entry);
+ rv_attach_trace_probe("nrp", call_function_single_entry, handle_vector_irq_entry);
+ }
+}
+
+static void detach_vector_irq(void)
+{
+ rv_detach_trace_probe("nrp", local_timer_entry, handle_vector_irq_entry);
+ if (IS_ENABLED(CONFIG_IRQ_WORK))
+ rv_detach_trace_probe("nrp", irq_work_entry, handle_vector_irq_entry);
+ if (IS_ENABLED(CONFIG_SMP)) {
+ rv_detach_trace_probe("nrp", reschedule_entry, handle_vector_irq_entry);
+ rv_detach_trace_probe("nrp", call_function_entry, handle_vector_irq_entry);
+ rv_detach_trace_probe("nrp", call_function_single_entry, handle_vector_irq_entry);
+ }
+}
+
+#else
+/* We assume irq_entry tracepoints are sufficient on other architectures */
+static void attach_vector_irq(void) { }
+static void detach_vector_irq(void) { }
+#endif
+
+static void handle_irq_entry(void *data, int irq, struct irqaction *action)
+{
+ da_handle_event_nrp(current, irq_entry_nrp);
+}
+
+static void handle_sched_need_resched(void *data, struct task_struct *tsk,
+ int cpu, int tif)
+{
+ /*
+ * Although need_resched leads to both the rescheduling and preempt_irq
+ * states, it is safer to start the monitor always in preempt_irq,
+ * which may not mirror the system state but makes the monitor simpler,
+ */
+ if (tif == TIF_NEED_RESCHED)
+ da_handle_start_event_nrp(tsk, sched_need_resched_nrp);
+}
+
+static void handle_schedule_entry(void *data, bool preempt)
+{
+ if (preempt)
+ da_handle_event_nrp(current, schedule_entry_preempt_nrp);
+ else
+ da_handle_event_nrp(current, schedule_entry_nrp);
+}
+
+static int enable_nrp(void)
+{
+ int retval;
+
+ retval = da_monitor_init_nrp();
+ if (retval)
+ return retval;
+
+ rv_attach_trace_probe("nrp", irq_handler_entry, handle_irq_entry);
+ rv_attach_trace_probe("nrp", sched_set_need_resched_tp, handle_sched_need_resched);
+ rv_attach_trace_probe("nrp", sched_entry_tp, handle_schedule_entry);
+ attach_vector_irq();
+
+ return 0;
+}
+
+static void disable_nrp(void)
+{
+ rv_nrp.enabled = 0;
+
+ rv_detach_trace_probe("nrp", irq_handler_entry, handle_irq_entry);
+ rv_detach_trace_probe("nrp", sched_set_need_resched_tp, handle_sched_need_resched);
+ rv_detach_trace_probe("nrp", sched_entry_tp, handle_schedule_entry);
+ detach_vector_irq();
+
+ da_monitor_destroy_nrp();
+}
+
+static struct rv_monitor rv_nrp = {
+ .name = "nrp",
+ .description = "need resched preempts.",
+ .enable = enable_nrp,
+ .disable = disable_nrp,
+ .reset = da_monitor_reset_all_nrp,
+ .enabled = 0,
+};
+
+static int __init register_nrp(void)
+{
+ return rv_register_monitor(&rv_nrp, &rv_sched);
+}
+
+static void __exit unregister_nrp(void)
+{
+ rv_unregister_monitor(&rv_nrp);
+}
+
+module_init(register_nrp);
+module_exit(unregister_nrp);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Gabriele Monaco <gmonaco@redhat.com>");
+MODULE_DESCRIPTION("nrp: need resched preempts.");
diff --git a/kernel/trace/rv/monitors/nrp/nrp.h b/kernel/trace/rv/monitors/nrp/nrp.h
new file mode 100644
index 0000000000000..c9f12207cbf6b
--- /dev/null
+++ b/kernel/trace/rv/monitors/nrp/nrp.h
@@ -0,0 +1,75 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Automatically generated C representation of nrp automaton
+ * For further information about this format, see kernel documentation:
+ * Documentation/trace/rv/deterministic_automata.rst
+ */
+
+enum states_nrp {
+ preempt_irq_nrp = 0,
+ any_thread_running_nrp,
+ nested_preempt_nrp,
+ rescheduling_nrp,
+ state_max_nrp
+};
+
+#define INVALID_STATE state_max_nrp
+
+enum events_nrp {
+ irq_entry_nrp = 0,
+ sched_need_resched_nrp,
+ schedule_entry_nrp,
+ schedule_entry_preempt_nrp,
+ event_max_nrp
+};
+
+struct automaton_nrp {
+ char *state_names[state_max_nrp];
+ char *event_names[event_max_nrp];
+ unsigned char function[state_max_nrp][event_max_nrp];
+ unsigned char initial_state;
+ bool final_states[state_max_nrp];
+};
+
+static const struct automaton_nrp automaton_nrp = {
+ .state_names = {
+ "preempt_irq",
+ "any_thread_running",
+ "nested_preempt",
+ "rescheduling"
+ },
+ .event_names = {
+ "irq_entry",
+ "sched_need_resched",
+ "schedule_entry",
+ "schedule_entry_preempt"
+ },
+ .function = {
+ {
+ preempt_irq_nrp,
+ preempt_irq_nrp,
+ nested_preempt_nrp,
+ nested_preempt_nrp
+ },
+ {
+ any_thread_running_nrp,
+ rescheduling_nrp,
+ any_thread_running_nrp,
+ INVALID_STATE
+ },
+ {
+ nested_preempt_nrp,
+ preempt_irq_nrp,
+ any_thread_running_nrp,
+ any_thread_running_nrp
+ },
+ {
+ preempt_irq_nrp,
+ rescheduling_nrp,
+ any_thread_running_nrp,
+ any_thread_running_nrp
+ },
+ },
+ .initial_state = preempt_irq_nrp,
+ .final_states = { 0, 1, 0, 0 },
+};
diff --git a/kernel/trace/rv/monitors/nrp/nrp_trace.h b/kernel/trace/rv/monitors/nrp/nrp_trace.h
new file mode 100644
index 0000000000000..2e13497de3b6f
--- /dev/null
+++ b/kernel/trace/rv/monitors/nrp/nrp_trace.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Snippet to be included in rv_trace.h
+ */
+
+#ifdef CONFIG_RV_MON_NRP
+DEFINE_EVENT(event_da_monitor_id, event_nrp,
+ TP_PROTO(int id, char *state, char *event, char *next_state, bool final_state),
+ TP_ARGS(id, state, event, next_state, final_state));
+
+DEFINE_EVENT(error_da_monitor_id, error_nrp,
+ TP_PROTO(int id, char *state, char *event),
+ TP_ARGS(id, state, event));
+#endif /* CONFIG_RV_MON_NRP */
diff --git a/kernel/trace/rv/monitors/sched/Kconfig b/kernel/trace/rv/monitors/sched/Kconfig
index ae3eb410abd78..aa16456da8647 100644
--- a/kernel/trace/rv/monitors/sched/Kconfig
+++ b/kernel/trace/rv/monitors/sched/Kconfig
@@ -2,6 +2,7 @@
#
config RV_MON_SCHED
depends on RV
+ depends on RV_PER_TASK_MONITORS >= 3
bool "sched monitor"
help
Collection of monitors to check the scheduler behaves according to specifications.
diff --git a/kernel/trace/rv/monitors/sssw/Kconfig b/kernel/trace/rv/monitors/sssw/Kconfig
new file mode 100644
index 0000000000000..23b7eeb38bbfc
--- /dev/null
+++ b/kernel/trace/rv/monitors/sssw/Kconfig
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+config RV_MON_SSSW
+ depends on RV
+ depends on RV_MON_SCHED
+ default y
+ select DA_MON_EVENTS_ID
+ bool "sssw monitor"
+ help
+ Monitor to ensure sched_set_state to sleepable leads to sleeping and
+ sleeping tasks require wakeup.
+ This monitor is part of the sched monitors collection.
+
+ For further information, see:
+ Documentation/trace/rv/monitor_sched.rst
diff --git a/kernel/trace/rv/monitors/sssw/sssw.c b/kernel/trace/rv/monitors/sssw/sssw.c
new file mode 100644
index 0000000000000..84b8d890d9d4a
--- /dev/null
+++ b/kernel/trace/rv/monitors/sssw/sssw.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/ftrace.h>
+#include <linux/tracepoint.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/rv.h>
+#include <rv/instrumentation.h>
+#include <rv/da_monitor.h>
+
+#define MODULE_NAME "sssw"
+
+#include <trace/events/sched.h>
+#include <trace/events/signal.h>
+#include <rv_trace.h>
+#include <monitors/sched/sched.h>
+
+#include "sssw.h"
+
+static struct rv_monitor rv_sssw;
+DECLARE_DA_MON_PER_TASK(sssw, unsigned char);
+
+static void handle_sched_set_state(void *data, struct task_struct *tsk, int state)
+{
+ if (state == TASK_RUNNING)
+ da_handle_start_event_sssw(tsk, sched_set_state_runnable_sssw);
+ else
+ da_handle_event_sssw(tsk, sched_set_state_sleepable_sssw);
+}
+
+static void handle_sched_switch(void *data, bool preempt,
+ struct task_struct *prev,
+ struct task_struct *next,
+ unsigned int prev_state)
+{
+ if (preempt)
+ da_handle_event_sssw(prev, sched_switch_preempt_sssw);
+ else if (prev_state == TASK_RUNNING)
+ da_handle_event_sssw(prev, sched_switch_yield_sssw);
+ else if (prev_state == TASK_RTLOCK_WAIT)
+ /* special case of sleeping task with racy conditions */
+ da_handle_event_sssw(prev, sched_switch_blocking_sssw);
+ else
+ da_handle_event_sssw(prev, sched_switch_suspend_sssw);
+ da_handle_event_sssw(next, sched_switch_in_sssw);
+}
+
+static void handle_sched_wakeup(void *data, struct task_struct *p)
+{
+ /*
+ * Wakeup can also lead to signal_wakeup although the system is
+ * actually runnable. The monitor can safely start with this event.
+ */
+ da_handle_start_event_sssw(p, sched_wakeup_sssw);
+}
+
+static void handle_signal_deliver(void *data, int sig,
+ struct kernel_siginfo *info,
+ struct k_sigaction *ka)
+{
+ da_handle_event_sssw(current, signal_deliver_sssw);
+}
+
+static int enable_sssw(void)
+{
+ int retval;
+
+ retval = da_monitor_init_sssw();
+ if (retval)
+ return retval;
+
+ rv_attach_trace_probe("sssw", sched_set_state_tp, handle_sched_set_state);
+ rv_attach_trace_probe("sssw", sched_switch, handle_sched_switch);
+ rv_attach_trace_probe("sssw", sched_wakeup, handle_sched_wakeup);
+ rv_attach_trace_probe("sssw", signal_deliver, handle_signal_deliver);
+
+ return 0;
+}
+
+static void disable_sssw(void)
+{
+ rv_sssw.enabled = 0;
+
+ rv_detach_trace_probe("sssw", sched_set_state_tp, handle_sched_set_state);
+ rv_detach_trace_probe("sssw", sched_switch, handle_sched_switch);
+ rv_detach_trace_probe("sssw", sched_wakeup, handle_sched_wakeup);
+ rv_detach_trace_probe("sssw", signal_deliver, handle_signal_deliver);
+
+ da_monitor_destroy_sssw();
+}
+
+static struct rv_monitor rv_sssw = {
+ .name = "sssw",
+ .description = "set state sleep and wakeup.",
+ .enable = enable_sssw,
+ .disable = disable_sssw,
+ .reset = da_monitor_reset_all_sssw,
+ .enabled = 0,
+};
+
+static int __init register_sssw(void)
+{
+ return rv_register_monitor(&rv_sssw, &rv_sched);
+}
+
+static void __exit unregister_sssw(void)
+{
+ rv_unregister_monitor(&rv_sssw);
+}
+
+module_init(register_sssw);
+module_exit(unregister_sssw);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Gabriele Monaco <gmonaco@redhat.com>");
+MODULE_DESCRIPTION("sssw: set state sleep and wakeup.");
diff --git a/kernel/trace/rv/monitors/sssw/sssw.h b/kernel/trace/rv/monitors/sssw/sssw.h
new file mode 100644
index 0000000000000..243d54050c943
--- /dev/null
+++ b/kernel/trace/rv/monitors/sssw/sssw.h
@@ -0,0 +1,105 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Automatically generated C representation of sssw automaton
+ * For further information about this format, see kernel documentation:
+ * Documentation/trace/rv/deterministic_automata.rst
+ */
+
+enum states_sssw {
+ runnable_sssw = 0,
+ signal_wakeup_sssw,
+ sleepable_sssw,
+ sleeping_sssw,
+ state_max_sssw
+};
+
+#define INVALID_STATE state_max_sssw
+
+enum events_sssw {
+ sched_set_state_runnable_sssw = 0,
+ sched_set_state_sleepable_sssw,
+ sched_switch_blocking_sssw,
+ sched_switch_in_sssw,
+ sched_switch_preempt_sssw,
+ sched_switch_suspend_sssw,
+ sched_switch_yield_sssw,
+ sched_wakeup_sssw,
+ signal_deliver_sssw,
+ event_max_sssw
+};
+
+struct automaton_sssw {
+ char *state_names[state_max_sssw];
+ char *event_names[event_max_sssw];
+ unsigned char function[state_max_sssw][event_max_sssw];
+ unsigned char initial_state;
+ bool final_states[state_max_sssw];
+};
+
+static const struct automaton_sssw automaton_sssw = {
+ .state_names = {
+ "runnable",
+ "signal_wakeup",
+ "sleepable",
+ "sleeping"
+ },
+ .event_names = {
+ "sched_set_state_runnable",
+ "sched_set_state_sleepable",
+ "sched_switch_blocking",
+ "sched_switch_in",
+ "sched_switch_preempt",
+ "sched_switch_suspend",
+ "sched_switch_yield",
+ "sched_wakeup",
+ "signal_deliver"
+ },
+ .function = {
+ {
+ runnable_sssw,
+ sleepable_sssw,
+ sleeping_sssw,
+ runnable_sssw,
+ runnable_sssw,
+ INVALID_STATE,
+ runnable_sssw,
+ runnable_sssw,
+ runnable_sssw
+ },
+ {
+ INVALID_STATE,
+ sleepable_sssw,
+ INVALID_STATE,
+ signal_wakeup_sssw,
+ signal_wakeup_sssw,
+ INVALID_STATE,
+ signal_wakeup_sssw,
+ signal_wakeup_sssw,
+ runnable_sssw
+ },
+ {
+ runnable_sssw,
+ sleepable_sssw,
+ sleeping_sssw,
+ sleepable_sssw,
+ sleepable_sssw,
+ sleeping_sssw,
+ signal_wakeup_sssw,
+ runnable_sssw,
+ sleepable_sssw
+ },
+ {
+ INVALID_STATE,
+ INVALID_STATE,
+ INVALID_STATE,
+ INVALID_STATE,
+ INVALID_STATE,
+ INVALID_STATE,
+ INVALID_STATE,
+ runnable_sssw,
+ INVALID_STATE
+ },
+ },
+ .initial_state = runnable_sssw,
+ .final_states = { 1, 0, 0, 0 },
+};
diff --git a/kernel/trace/rv/monitors/sssw/sssw_trace.h b/kernel/trace/rv/monitors/sssw/sssw_trace.h
new file mode 100644
index 0000000000000..6c03cfc6960bf
--- /dev/null
+++ b/kernel/trace/rv/monitors/sssw/sssw_trace.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Snippet to be included in rv_trace.h
+ */
+
+#ifdef CONFIG_RV_MON_SSSW
+DEFINE_EVENT(event_da_monitor_id, event_sssw,
+ TP_PROTO(int id, char *state, char *event, char *next_state, bool final_state),
+ TP_ARGS(id, state, event, next_state, final_state));
+
+DEFINE_EVENT(error_da_monitor_id, error_sssw,
+ TP_PROTO(int id, char *state, char *event),
+ TP_ARGS(id, state, event));
+#endif /* CONFIG_RV_MON_SSSW */
diff --git a/kernel/trace/rv/rv_trace.h b/kernel/trace/rv/rv_trace.h
index fa9613cb94699..4c89032f01efe 100644
--- a/kernel/trace/rv/rv_trace.h
+++ b/kernel/trace/rv/rv_trace.h
@@ -123,6 +123,8 @@ DECLARE_EVENT_CLASS(error_da_monitor_id,
#include <monitors/wwnr/wwnr_trace.h>
#include <monitors/snroc/snroc_trace.h>
+#include <monitors/nrp/nrp_trace.h>
+#include <monitors/sssw/sssw_trace.h>
// Add new monitors based on CONFIG_DA_MON_EVENTS_ID here
#endif /* CONFIG_DA_MON_EVENTS_ID */
diff --git a/tools/verification/models/sched/nrp.dot b/tools/verification/models/sched/nrp.dot
new file mode 100644
index 0000000000000..77bb64669416e
--- /dev/null
+++ b/tools/verification/models/sched/nrp.dot
@@ -0,0 +1,29 @@
+digraph state_automaton {
+ center = true;
+ size = "7,11";
+ {node [shape = doublecircle] "any_thread_running"};
+ {node [shape = circle] "any_thread_running"};
+ {node [shape = circle] "nested_preempt"};
+ {node [shape = plaintext, style=invis, label=""] "__init_preempt_irq"};
+ {node [shape = circle] "preempt_irq"};
+ {node [shape = circle] "rescheduling"};
+ "__init_preempt_irq" -> "preempt_irq";
+ "any_thread_running" [label = "any_thread_running", color = green3];
+ "any_thread_running" -> "any_thread_running" [ label = "schedule_entry\nirq_entry" ];
+ "any_thread_running" -> "rescheduling" [ label = "sched_need_resched" ];
+ "nested_preempt" [label = "nested_preempt"];
+ "nested_preempt" -> "any_thread_running" [ label = "schedule_entry_preempt\nschedule_entry" ];
+ "nested_preempt" -> "nested_preempt" [ label = "irq_entry" ];
+ "nested_preempt" -> "preempt_irq" [ label = "sched_need_resched" ];
+ "preempt_irq" [label = "preempt_irq"];
+ "preempt_irq" -> "nested_preempt" [ label = "schedule_entry_preempt\nschedule_entry" ];
+ "preempt_irq" -> "preempt_irq" [ label = "irq_entry\nsched_need_resched" ];
+ "rescheduling" [label = "rescheduling"];
+ "rescheduling" -> "any_thread_running" [ label = "schedule_entry_preempt\nschedule_entry" ];
+ "rescheduling" -> "preempt_irq" [ label = "irq_entry" ];
+ "rescheduling" -> "rescheduling" [ label = "sched_need_resched" ];
+ { rank = min ;
+ "__init_preempt_irq";
+ "preempt_irq";
+ }
+}
diff --git a/tools/verification/models/sched/sssw.dot b/tools/verification/models/sched/sssw.dot
new file mode 100644
index 0000000000000..4994c3e876be8
--- /dev/null
+++ b/tools/verification/models/sched/sssw.dot
@@ -0,0 +1,30 @@
+digraph state_automaton {
+ center = true;
+ size = "7,11";
+ {node [shape = plaintext, style=invis, label=""] "__init_runnable"};
+ {node [shape = doublecircle] "runnable"};
+ {node [shape = circle] "runnable"};
+ {node [shape = circle] "signal_wakeup"};
+ {node [shape = circle] "sleepable"};
+ {node [shape = circle] "sleeping"};
+ "__init_runnable" -> "runnable";
+ "runnable" [label = "runnable", color = green3];
+ "runnable" -> "runnable" [ label = "sched_set_state_runnable\nsched_wakeup\nsched_switch_in\nsched_switch_yield\nsched_switch_preempt\nsignal_deliver" ];
+ "runnable" -> "sleepable" [ label = "sched_set_state_sleepable" ];
+ "runnable" -> "sleeping" [ label = "sched_switch_blocking" ];
+ "signal_wakeup" [label = "signal_wakeup"];
+ "signal_wakeup" -> "runnable" [ label = "signal_deliver" ];
+ "signal_wakeup" -> "signal_wakeup" [ label = "sched_switch_in\nsched_switch_preempt\nsched_switch_yield\nsched_wakeup" ];
+ "signal_wakeup" -> "sleepable" [ label = "sched_set_state_sleepable" ];
+ "sleepable" [label = "sleepable"];
+ "sleepable" -> "runnable" [ label = "sched_set_state_runnable\nsched_wakeup" ];
+ "sleepable" -> "signal_wakeup" [ label = "sched_switch_yield" ];
+ "sleepable" -> "sleepable" [ label = "sched_set_state_sleepable\nsched_switch_in\nsched_switch_preempt\nsignal_deliver" ];
+ "sleepable" -> "sleeping" [ label = "sched_switch_suspend\nsched_switch_blocking" ];
+ "sleeping" [label = "sleeping"];
+ "sleeping" -> "runnable" [ label = "sched_wakeup" ];
+ { rank = min ;
+ "__init_runnable";
+ "runnable";
+ }
+}
--
2.50.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v4 14/14] rv: Add opid per-cpu monitor
[not found] <20250721082325.71554-1-gmonaco@redhat.com>
2025-07-21 8:23 ` [PATCH v4 12/14] rv: Replace tss and sncid monitors with more complete sts Gabriele Monaco
2025-07-21 8:23 ` [PATCH v4 13/14] rv: Add nrp and sssw per-task monitors Gabriele Monaco
@ 2025-07-21 8:23 ` Gabriele Monaco
2 siblings, 0 replies; 5+ messages in thread
From: Gabriele Monaco @ 2025-07-21 8:23 UTC (permalink / raw)
To: linux-kernel, Steven Rostedt, Jonathan Corbet, Masami Hiramatsu,
linux-trace-kernel, linux-doc
Cc: Gabriele Monaco, Ingo Molnar, Peter Zijlstra, Nam Cao,
Tomas Glozar, Juri Lelli, Clark Williams, John Kacur
Add a per-cpu monitor as part of the sched model:
* opid: operations with preemption and irq disabled
Monitor to ensure wakeup and need_resched occur with irq and
preemption disabled or in irq handlers.
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
---
Documentation/trace/rv/monitor_sched.rst | 55 +++++++
kernel/trace/rv/Kconfig | 1 +
kernel/trace/rv/Makefile | 1 +
kernel/trace/rv/monitors/opid/Kconfig | 19 +++
kernel/trace/rv/monitors/opid/opid.c | 169 +++++++++++++++++++++
kernel/trace/rv/monitors/opid/opid.h | 104 +++++++++++++
kernel/trace/rv/monitors/opid/opid_trace.h | 15 ++
kernel/trace/rv/rv_trace.h | 1 +
tools/verification/models/sched/opid.dot | 35 +++++
9 files changed, 400 insertions(+)
create mode 100644 kernel/trace/rv/monitors/opid/Kconfig
create mode 100644 kernel/trace/rv/monitors/opid/opid.c
create mode 100644 kernel/trace/rv/monitors/opid/opid.h
create mode 100644 kernel/trace/rv/monitors/opid/opid_trace.h
create mode 100644 tools/verification/models/sched/opid.dot
diff --git a/Documentation/trace/rv/monitor_sched.rst b/Documentation/trace/rv/monitor_sched.rst
index 11ef963cb5780..3f8381ad9ec7b 100644
--- a/Documentation/trace/rv/monitor_sched.rst
+++ b/Documentation/trace/rv/monitor_sched.rst
@@ -341,6 +341,61 @@ can be triggered also by preemption, but cannot occur after the task got to
| | switch_yield
+-----------+ wakeup
+Monitor opid
+------------
+
+The operations with preemption and irq disabled (opid) monitor ensures
+operations like ``wakeup`` and ``need_resched`` occur with interrupts and
+preemption disabled or during interrupt context, in such case preemption may
+not be disabled explicitly.
+``need_resched`` can be set by some RCU internals functions, in which case it
+doesn't match a task wakeup and might occur with only interrupts disabled::
+
+ | sched_need_resched
+ | sched_waking
+ | irq_entry
+ | +--------------------+
+ v v |
+ +------------------------------------------------------+
+ +----------- | disabled | <+
+ | +------------------------------------------------------+ |
+ | | ^ |
+ | | preempt_disable sched_need_resched |
+ | preempt_enable | +--------------------+ |
+ | v | v | |
+ | +------------------------------------------------------+ |
+ | | irq_disabled | |
+ | +------------------------------------------------------+ |
+ | | | ^ |
+ | irq_entry irq_entry | | |
+ | sched_need_resched v | irq_disable |
+ | sched_waking +--------------+ | | |
+ | +----- | | irq_enable | |
+ | | | in_irq | | | |
+ | +----> | | | | |
+ | +--------------+ | | irq_disable
+ | | | | |
+ | irq_enable | irq_enable | | |
+ | v v | |
+ | #======================================================# |
+ | H enabled H |
+ | #======================================================# |
+ | | ^ ^ preempt_enable | |
+ | preempt_disable preempt_enable +--------------------+ |
+ | v | |
+ | +------------------+ | |
+ +----------> | preempt_disabled | -+ |
+ +------------------+ |
+ | |
+ +-------------------------------------------------------+
+
+This monitor is designed to work on ``PREEMPT_RT`` kernels, the special case of
+events occurring in interrupt context is a shortcut to identify valid scenarios
+where the preemption tracepoints might not be visible, during interrupts
+preemption is always disabled. On non- ``PREEMPT_RT`` kernels, the interrupts
+might invoke a softirq to set ``need_resched`` and wake up a task. This is
+another special case that is currently not supported by the monitor.
+
References
----------
diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig
index 59d0db898d4ab..5b4be87ba59d3 100644
--- a/kernel/trace/rv/Kconfig
+++ b/kernel/trace/rv/Kconfig
@@ -57,6 +57,7 @@ source "kernel/trace/rv/monitors/snep/Kconfig"
source "kernel/trace/rv/monitors/sts/Kconfig"
source "kernel/trace/rv/monitors/nrp/Kconfig"
source "kernel/trace/rv/monitors/sssw/Kconfig"
+source "kernel/trace/rv/monitors/opid/Kconfig"
# Add new sched monitors here
source "kernel/trace/rv/monitors/rtapp/Kconfig"
diff --git a/kernel/trace/rv/Makefile b/kernel/trace/rv/Makefile
index 2afac88539d3f..750e4ad6fa0ff 100644
--- a/kernel/trace/rv/Makefile
+++ b/kernel/trace/rv/Makefile
@@ -16,6 +16,7 @@ obj-$(CONFIG_RV_MON_SLEEP) += monitors/sleep/sleep.o
obj-$(CONFIG_RV_MON_STS) += monitors/sts/sts.o
obj-$(CONFIG_RV_MON_NRP) += monitors/nrp/nrp.o
obj-$(CONFIG_RV_MON_SSSW) += monitors/sssw/sssw.o
+obj-$(CONFIG_RV_MON_OPID) += monitors/opid/opid.o
# Add new monitors here
obj-$(CONFIG_RV_REACTORS) += rv_reactors.o
obj-$(CONFIG_RV_REACT_PRINTK) += reactor_printk.o
diff --git a/kernel/trace/rv/monitors/opid/Kconfig b/kernel/trace/rv/monitors/opid/Kconfig
new file mode 100644
index 0000000000000..561d32da572b2
--- /dev/null
+++ b/kernel/trace/rv/monitors/opid/Kconfig
@@ -0,0 +1,19 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+config RV_MON_OPID
+ depends on RV
+ depends on TRACE_IRQFLAGS
+ depends on TRACE_PREEMPT_TOGGLE
+ depends on RV_MON_SCHED
+ default y if PREEMPT_RT
+ select DA_MON_EVENTS_IMPLICIT
+ bool "opid monitor"
+ help
+ Monitor to ensure operations like wakeup and need resched occur with
+ interrupts and preemption disabled or during IRQs, where preemption
+ may not be disabled explicitly.
+
+ This monitor is unstable on !PREEMPT_RT, say N unless you are testing it.
+
+ For further information, see:
+ Documentation/trace/rv/monitor_sched.rst
diff --git a/kernel/trace/rv/monitors/opid/opid.c b/kernel/trace/rv/monitors/opid/opid.c
new file mode 100644
index 0000000000000..4f1902f24805c
--- /dev/null
+++ b/kernel/trace/rv/monitors/opid/opid.c
@@ -0,0 +1,169 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/ftrace.h>
+#include <linux/tracepoint.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/rv.h>
+#include <rv/instrumentation.h>
+#include <rv/da_monitor.h>
+
+#define MODULE_NAME "opid"
+
+#include <trace/events/sched.h>
+#include <trace/events/irq.h>
+#include <trace/events/preemptirq.h>
+#include <rv_trace.h>
+#include <monitors/sched/sched.h>
+
+#include "opid.h"
+
+static struct rv_monitor rv_opid;
+DECLARE_DA_MON_PER_CPU(opid, unsigned char);
+
+#ifdef CONFIG_X86_LOCAL_APIC
+#include <asm/trace/irq_vectors.h>
+
+static void handle_vector_irq_entry(void *data, int vector)
+{
+ da_handle_event_opid(irq_entry_opid);
+}
+
+static void attach_vector_irq(void)
+{
+ rv_attach_trace_probe("opid", local_timer_entry, handle_vector_irq_entry);
+ if (IS_ENABLED(CONFIG_IRQ_WORK))
+ rv_attach_trace_probe("opid", irq_work_entry, handle_vector_irq_entry);
+ if (IS_ENABLED(CONFIG_SMP)) {
+ rv_attach_trace_probe("opid", reschedule_entry, handle_vector_irq_entry);
+ rv_attach_trace_probe("opid", call_function_entry, handle_vector_irq_entry);
+ rv_attach_trace_probe("opid", call_function_single_entry, handle_vector_irq_entry);
+ }
+}
+
+static void detach_vector_irq(void)
+{
+ rv_detach_trace_probe("opid", local_timer_entry, handle_vector_irq_entry);
+ if (IS_ENABLED(CONFIG_IRQ_WORK))
+ rv_detach_trace_probe("opid", irq_work_entry, handle_vector_irq_entry);
+ if (IS_ENABLED(CONFIG_SMP)) {
+ rv_detach_trace_probe("opid", reschedule_entry, handle_vector_irq_entry);
+ rv_detach_trace_probe("opid", call_function_entry, handle_vector_irq_entry);
+ rv_detach_trace_probe("opid", call_function_single_entry, handle_vector_irq_entry);
+ }
+}
+
+#else
+/* We assume irq_entry tracepoints are sufficient on other architectures */
+static void attach_vector_irq(void) { }
+static void detach_vector_irq(void) { }
+#endif
+
+static void handle_irq_disable(void *data, unsigned long ip, unsigned long parent_ip)
+{
+ da_handle_event_opid(irq_disable_opid);
+}
+
+static void handle_irq_enable(void *data, unsigned long ip, unsigned long parent_ip)
+{
+ da_handle_event_opid(irq_enable_opid);
+}
+
+static void handle_irq_entry(void *data, int irq, struct irqaction *action)
+{
+ da_handle_event_opid(irq_entry_opid);
+}
+
+static void handle_preempt_disable(void *data, unsigned long ip, unsigned long parent_ip)
+{
+ da_handle_event_opid(preempt_disable_opid);
+}
+
+static void handle_preempt_enable(void *data, unsigned long ip, unsigned long parent_ip)
+{
+ da_handle_event_opid(preempt_enable_opid);
+}
+
+static void handle_sched_need_resched(void *data, struct task_struct *tsk, int cpu, int tif)
+{
+ /* The monitor's intitial state is not in_irq */
+ if (this_cpu_read(hardirq_context))
+ da_handle_event_opid(sched_need_resched_opid);
+ else
+ da_handle_start_event_opid(sched_need_resched_opid);
+}
+
+static void handle_sched_waking(void *data, struct task_struct *p)
+{
+ /* The monitor's intitial state is not in_irq */
+ if (this_cpu_read(hardirq_context))
+ da_handle_event_opid(sched_waking_opid);
+ else
+ da_handle_start_event_opid(sched_waking_opid);
+}
+
+static int enable_opid(void)
+{
+ int retval;
+
+ retval = da_monitor_init_opid();
+ if (retval)
+ return retval;
+
+ rv_attach_trace_probe("opid", irq_disable, handle_irq_disable);
+ rv_attach_trace_probe("opid", irq_enable, handle_irq_enable);
+ rv_attach_trace_probe("opid", irq_handler_entry, handle_irq_entry);
+ rv_attach_trace_probe("opid", preempt_disable, handle_preempt_disable);
+ rv_attach_trace_probe("opid", preempt_enable, handle_preempt_enable);
+ rv_attach_trace_probe("opid", sched_set_need_resched_tp, handle_sched_need_resched);
+ rv_attach_trace_probe("opid", sched_waking, handle_sched_waking);
+ attach_vector_irq();
+
+ return 0;
+}
+
+static void disable_opid(void)
+{
+ rv_opid.enabled = 0;
+
+ rv_detach_trace_probe("opid", irq_disable, handle_irq_disable);
+ rv_detach_trace_probe("opid", irq_enable, handle_irq_enable);
+ rv_detach_trace_probe("opid", irq_handler_entry, handle_irq_entry);
+ rv_detach_trace_probe("opid", preempt_disable, handle_preempt_disable);
+ rv_detach_trace_probe("opid", preempt_enable, handle_preempt_enable);
+ rv_detach_trace_probe("opid", sched_set_need_resched_tp, handle_sched_need_resched);
+ rv_detach_trace_probe("opid", sched_waking, handle_sched_waking);
+ detach_vector_irq();
+
+ da_monitor_destroy_opid();
+}
+
+/*
+ * This is the monitor register section.
+ */
+static struct rv_monitor rv_opid = {
+ .name = "opid",
+ .description = "operations with preemption and irq disabled.",
+ .enable = enable_opid,
+ .disable = disable_opid,
+ .reset = da_monitor_reset_all_opid,
+ .enabled = 0,
+};
+
+static int __init register_opid(void)
+{
+ rv_register_monitor(&rv_opid, &rv_sched);
+ return 0;
+}
+
+static void __exit unregister_opid(void)
+{
+ rv_unregister_monitor(&rv_opid);
+}
+
+module_init(register_opid);
+module_exit(unregister_opid);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Gabriele Monaco <gmonaco@redhat.com>");
+MODULE_DESCRIPTION("opid: operations with preemption and irq disabled.");
diff --git a/kernel/trace/rv/monitors/opid/opid.h b/kernel/trace/rv/monitors/opid/opid.h
new file mode 100644
index 0000000000000..b4b8c2ff7f643
--- /dev/null
+++ b/kernel/trace/rv/monitors/opid/opid.h
@@ -0,0 +1,104 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Automatically generated C representation of opid automaton
+ * For further information about this format, see kernel documentation:
+ * Documentation/trace/rv/deterministic_automata.rst
+ */
+
+enum states_opid {
+ disabled_opid = 0,
+ enabled_opid,
+ in_irq_opid,
+ irq_disabled_opid,
+ preempt_disabled_opid,
+ state_max_opid
+};
+
+#define INVALID_STATE state_max_opid
+
+enum events_opid {
+ irq_disable_opid = 0,
+ irq_enable_opid,
+ irq_entry_opid,
+ preempt_disable_opid,
+ preempt_enable_opid,
+ sched_need_resched_opid,
+ sched_waking_opid,
+ event_max_opid
+};
+
+struct automaton_opid {
+ char *state_names[state_max_opid];
+ char *event_names[event_max_opid];
+ unsigned char function[state_max_opid][event_max_opid];
+ unsigned char initial_state;
+ bool final_states[state_max_opid];
+};
+
+static const struct automaton_opid automaton_opid = {
+ .state_names = {
+ "disabled",
+ "enabled",
+ "in_irq",
+ "irq_disabled",
+ "preempt_disabled"
+ },
+ .event_names = {
+ "irq_disable",
+ "irq_enable",
+ "irq_entry",
+ "preempt_disable",
+ "preempt_enable",
+ "sched_need_resched",
+ "sched_waking"
+ },
+ .function = {
+ {
+ INVALID_STATE,
+ preempt_disabled_opid,
+ disabled_opid,
+ INVALID_STATE,
+ irq_disabled_opid,
+ disabled_opid,
+ disabled_opid
+ },
+ {
+ irq_disabled_opid,
+ INVALID_STATE,
+ INVALID_STATE,
+ preempt_disabled_opid,
+ enabled_opid,
+ INVALID_STATE,
+ INVALID_STATE
+ },
+ {
+ INVALID_STATE,
+ enabled_opid,
+ in_irq_opid,
+ INVALID_STATE,
+ INVALID_STATE,
+ in_irq_opid,
+ in_irq_opid
+ },
+ {
+ INVALID_STATE,
+ enabled_opid,
+ in_irq_opid,
+ disabled_opid,
+ INVALID_STATE,
+ irq_disabled_opid,
+ INVALID_STATE
+ },
+ {
+ disabled_opid,
+ INVALID_STATE,
+ INVALID_STATE,
+ INVALID_STATE,
+ enabled_opid,
+ INVALID_STATE,
+ INVALID_STATE
+ },
+ },
+ .initial_state = disabled_opid,
+ .final_states = { 0, 1, 0, 0, 0 },
+};
diff --git a/kernel/trace/rv/monitors/opid/opid_trace.h b/kernel/trace/rv/monitors/opid/opid_trace.h
new file mode 100644
index 0000000000000..3df6ff955c300
--- /dev/null
+++ b/kernel/trace/rv/monitors/opid/opid_trace.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Snippet to be included in rv_trace.h
+ */
+
+#ifdef CONFIG_RV_MON_OPID
+DEFINE_EVENT(event_da_monitor, event_opid,
+ TP_PROTO(char *state, char *event, char *next_state, bool final_state),
+ TP_ARGS(state, event, next_state, final_state));
+
+DEFINE_EVENT(error_da_monitor, error_opid,
+ TP_PROTO(char *state, char *event),
+ TP_ARGS(state, event));
+#endif /* CONFIG_RV_MON_OPID */
diff --git a/kernel/trace/rv/rv_trace.h b/kernel/trace/rv/rv_trace.h
index 4c89032f01efe..97708f4e6b4e0 100644
--- a/kernel/trace/rv/rv_trace.h
+++ b/kernel/trace/rv/rv_trace.h
@@ -62,6 +62,7 @@ DECLARE_EVENT_CLASS(error_da_monitor,
#include <monitors/scpd/scpd_trace.h>
#include <monitors/snep/snep_trace.h>
#include <monitors/sts/sts_trace.h>
+#include <monitors/opid/opid_trace.h>
// Add new monitors based on CONFIG_DA_MON_EVENTS_IMPLICIT here
#endif /* CONFIG_DA_MON_EVENTS_IMPLICIT */
diff --git a/tools/verification/models/sched/opid.dot b/tools/verification/models/sched/opid.dot
new file mode 100644
index 0000000000000..840052f6952b8
--- /dev/null
+++ b/tools/verification/models/sched/opid.dot
@@ -0,0 +1,35 @@
+digraph state_automaton {
+ center = true;
+ size = "7,11";
+ {node [shape = plaintext, style=invis, label=""] "__init_disabled"};
+ {node [shape = circle] "disabled"};
+ {node [shape = doublecircle] "enabled"};
+ {node [shape = circle] "enabled"};
+ {node [shape = circle] "in_irq"};
+ {node [shape = circle] "irq_disabled"};
+ {node [shape = circle] "preempt_disabled"};
+ "__init_disabled" -> "disabled";
+ "disabled" [label = "disabled"];
+ "disabled" -> "disabled" [ label = "sched_need_resched\nsched_waking\nirq_entry" ];
+ "disabled" -> "irq_disabled" [ label = "preempt_enable" ];
+ "disabled" -> "preempt_disabled" [ label = "irq_enable" ];
+ "enabled" [label = "enabled", color = green3];
+ "enabled" -> "enabled" [ label = "preempt_enable" ];
+ "enabled" -> "irq_disabled" [ label = "irq_disable" ];
+ "enabled" -> "preempt_disabled" [ label = "preempt_disable" ];
+ "in_irq" [label = "in_irq"];
+ "in_irq" -> "enabled" [ label = "irq_enable" ];
+ "in_irq" -> "in_irq" [ label = "sched_need_resched\nsched_waking\nirq_entry" ];
+ "irq_disabled" [label = "irq_disabled"];
+ "irq_disabled" -> "disabled" [ label = "preempt_disable" ];
+ "irq_disabled" -> "enabled" [ label = "irq_enable" ];
+ "irq_disabled" -> "in_irq" [ label = "irq_entry" ];
+ "irq_disabled" -> "irq_disabled" [ label = "sched_need_resched" ];
+ "preempt_disabled" [label = "preempt_disabled"];
+ "preempt_disabled" -> "disabled" [ label = "irq_disable" ];
+ "preempt_disabled" -> "enabled" [ label = "preempt_enable" ];
+ { rank = min ;
+ "__init_disabled";
+ "disabled";
+ }
+}
--
2.50.1
^ permalink raw reply related [flat|nested] 5+ messages in thread