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9162620eb6
Userspace real-time applications may have design flaws that they raise page faults in real-time threads, and thus have unexpected latencies. Add an linear temporal logic monitor to detect this scenario. Cc: John Ogness <john.ogness@linutronix.de> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Link: https://lore.kernel.org/78fea8a2de6d058241d3c6502c1a92910772b0ed.1752088709.git.namcao@linutronix.de Reviewed-by: Gabriele Monaco <gmonaco@redhat.com> Signed-off-by: Nam Cao <namcao@linutronix.de> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
89 lines
2.3 KiB
C
89 lines
2.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/ftrace.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/rv.h>
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#include <linux/sched/deadline.h>
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#include <linux/sched/rt.h>
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#include <linux/tracepoint.h>
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#include <rv/instrumentation.h>
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#define MODULE_NAME "pagefault"
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#include <rv_trace.h>
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#include <trace/events/exceptions.h>
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#include <monitors/rtapp/rtapp.h>
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#include "pagefault.h"
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#include <rv/ltl_monitor.h>
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static void ltl_atoms_fetch(struct task_struct *task, struct ltl_monitor *mon)
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{
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/*
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* This includes "actual" real-time tasks and also PI-boosted
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* tasks. A task being PI-boosted means it is blocking an "actual"
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* real-task, therefore it should also obey the monitor's rule,
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* otherwise the "actual" real-task may be delayed.
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*/
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ltl_atom_set(mon, LTL_RT, rt_or_dl_task(task));
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}
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static void ltl_atoms_init(struct task_struct *task, struct ltl_monitor *mon, bool task_creation)
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{
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if (task_creation)
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ltl_atom_set(mon, LTL_PAGEFAULT, false);
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}
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static void handle_page_fault(void *data, unsigned long address, struct pt_regs *regs,
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unsigned long error_code)
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{
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ltl_atom_pulse(current, LTL_PAGEFAULT, true);
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}
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static int enable_pagefault(void)
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{
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int retval;
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retval = ltl_monitor_init();
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if (retval)
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return retval;
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rv_attach_trace_probe("rtapp_pagefault", page_fault_kernel, handle_page_fault);
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rv_attach_trace_probe("rtapp_pagefault", page_fault_user, handle_page_fault);
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return 0;
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}
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static void disable_pagefault(void)
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{
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rv_detach_trace_probe("rtapp_pagefault", page_fault_kernel, handle_page_fault);
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rv_detach_trace_probe("rtapp_pagefault", page_fault_user, handle_page_fault);
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ltl_monitor_destroy();
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}
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static struct rv_monitor rv_pagefault = {
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.name = "pagefault",
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.description = "Monitor that RT tasks do not raise page faults",
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.enable = enable_pagefault,
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.disable = disable_pagefault,
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};
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static int __init register_pagefault(void)
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{
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return rv_register_monitor(&rv_pagefault, &rv_rtapp);
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}
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static void __exit unregister_pagefault(void)
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{
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rv_unregister_monitor(&rv_pagefault);
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}
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module_init(register_pagefault);
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module_exit(unregister_pagefault);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Nam Cao <namcao@linutronix.de>");
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MODULE_DESCRIPTION("pagefault: Monitor that RT tasks do not raise page faults");
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