From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, "Paul E. McKenney" <paulmck@kernel.org>,
Andy Lutomirski <luto@kernel.org>,
Alexandre Chartre <alexandre.chartre@oracle.com>,
Frederic Weisbecker <frederic@kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Petr Mladek <pmladek@suse.com>,
Steven Rostedt <rostedt@goodmis.org>,
Joel Fernandes <joel@joelfernandes.org>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Juergen Gross <jgross@suse.com>, Brian Gerst <brgerst@gmail.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Will Deacon <will@kernel.org>,
Tom Lendacky <thomas.lendacky@amd.com>,
Wei Liu <wei.liu@kernel.org>,
Michael Kelley <mikelley@microsoft.com>,
Jason Chen CJ <jason.cj.chen@intel.com>,
Zhao Yakui <yakui.zhao@intel.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>
Subject: [patch V6 02/37] tracing/hwlat: Split ftrace_nmi_enter/exit()
Date: Sat, 16 May 2020 01:45:49 +0200 [thread overview]
Message-ID: <20200515235124.577025789@linutronix.de> (raw)
In-Reply-To: 20200515234547.710474468@linutronix.de
The hardware latency tracer calls into timekeeping and ends up in
various instrumentable functions which is problematic vs. the kprobe
handling especially the text poke machinery. It's invoked from
nmi_enter/exit(), i.e. non-instrumentable code.
Split it into two parts:
1) NMI counter, only invoked on nmi_enter() and noinstr safe
2) NMI timestamping, to be invoked from instrumentable code
Move it into the rcu is watching regions of nmi_enter/exit() even
if there is no actual RCU dependency right now but there is also
no point in having it early.
The actual split of nmi_enter/exit() is done in a separate step.
Requested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
include/linux/ftrace_irq.h | 31 +++++++++++++++++++------------
include/linux/hardirq.h | 5 +++--
kernel/trace/trace_hwlat.c | 19 ++++++++++++-------
3 files changed, 34 insertions(+), 21 deletions(-)
--- a/include/linux/ftrace_irq.h
+++ b/include/linux/ftrace_irq.h
@@ -4,23 +4,30 @@
#ifdef CONFIG_HWLAT_TRACER
extern bool trace_hwlat_callback_enabled;
-extern void trace_hwlat_callback(bool enter);
-#endif
+extern void trace_hwlat_count_nmi(void);
+extern void trace_hwlat_timestamp(bool enter);
-static inline void ftrace_nmi_enter(void)
+static __always_inline void ftrace_count_nmi(void)
{
-#ifdef CONFIG_HWLAT_TRACER
- if (trace_hwlat_callback_enabled)
- trace_hwlat_callback(true);
-#endif
+ if (unlikely(trace_hwlat_callback_enabled))
+ trace_hwlat_count_nmi();
}
-static inline void ftrace_nmi_exit(void)
+static __always_inline void ftrace_nmi_handler_enter(void)
{
-#ifdef CONFIG_HWLAT_TRACER
- if (trace_hwlat_callback_enabled)
- trace_hwlat_callback(false);
-#endif
+ if (unlikely(trace_hwlat_callback_enabled))
+ trace_hwlat_timestamp(true);
}
+static __always_inline void ftrace_nmi_handler_exit(void)
+{
+ if (unlikely(trace_hwlat_callback_enabled))
+ trace_hwlat_timestamp(false);
+}
+#else /* CONFIG_HWLAT_TRACER */
+static inline void ftrace_count_nmi(void) {}
+static inline void ftrace_nmi_handler_enter(void) {}
+static inline void ftrace_nmi_handler_exit(void) {}
+#endif
+
#endif /* _LINUX_FTRACE_IRQ_H */
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -82,20 +82,21 @@ extern void irq_exit(void);
arch_nmi_enter(); \
printk_nmi_enter(); \
lockdep_off(); \
- ftrace_nmi_enter(); \
BUG_ON(in_nmi() == NMI_MASK); \
__preempt_count_add(NMI_OFFSET + HARDIRQ_OFFSET); \
rcu_nmi_enter(); \
lockdep_hardirq_enter(); \
+ ftrace_count_nmi(); \
+ ftrace_nmi_handler_enter(); \
} while (0)
#define nmi_exit() \
do { \
+ ftrace_nmi_handler_exit(); \
lockdep_hardirq_exit(); \
rcu_nmi_exit(); \
BUG_ON(!in_nmi()); \
__preempt_count_sub(NMI_OFFSET + HARDIRQ_OFFSET); \
- ftrace_nmi_exit(); \
lockdep_on(); \
printk_nmi_exit(); \
arch_nmi_exit(); \
--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -132,21 +132,26 @@ static void trace_hwlat_sample(struct hw
}
/*
+ * Count NMIs in nmi_enter(). Does not take timestamps
+ * because the timestamping callchain cannot be invoked
+ * from noinstr sections.
+ */
+noinstr void trace_hwlat_count_nmi(void)
+{
+ if (smp_processor_id() == nmi_cpu)
+ nmi_count++;
+}
+
+/*
* Timestamping uses ktime_get_mono_fast(), the NMI safe access to
* CLOCK_MONOTONIC.
*/
-void trace_hwlat_callback(bool enter)
+void trace_hwlat_timestamp(bool enter)
{
- if (smp_processor_id() != nmi_cpu)
- return;
-
if (enter)
nmi_ts_start = ktime_get_mono_fast_ns();
else
nmi_total_ts += ktime_get_mono_fast_ns() - nmi_ts_start;
-
- if (enter)
- nmi_count++;
}
/**
next prev parent reply other threads:[~2020-05-16 0:10 UTC|newest]
Thread overview: 159+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-15 23:45 [patch V6 00/37] x86/entry: Rework leftovers and merge plan Thomas Gleixner
2020-05-15 23:45 ` [patch V6 01/37] tracing/hwlat: Use ktime_get_mono_fast_ns() Thomas Gleixner
2020-05-19 21:26 ` Steven Rostedt
2020-05-19 21:45 ` Thomas Gleixner
2020-05-19 22:18 ` Steven Rostedt
2020-05-20 19:51 ` Thomas Gleixner
2020-05-20 20:14 ` Peter Zijlstra
2020-05-20 22:20 ` Thomas Gleixner
2020-05-15 23:45 ` Thomas Gleixner [this message]
2020-05-19 22:23 ` [patch V6 02/37] tracing/hwlat: Split ftrace_nmi_enter/exit() Steven Rostedt
2020-05-15 23:45 ` [patch V6 03/37] nmi, tracing: Provide nmi_enter/exit_notrace() Thomas Gleixner
2020-05-17 5:12 ` Andy Lutomirski
2020-05-19 22:24 ` Steven Rostedt
2020-05-15 23:45 ` [patch V6 04/37] x86: Make hardware latency tracing explicit Thomas Gleixner
2020-05-17 5:36 ` Andy Lutomirski
2020-05-17 8:48 ` Thomas Gleixner
2020-05-18 5:50 ` Andy Lutomirski
2020-05-18 8:03 ` Thomas Gleixner
2020-05-18 20:42 ` Andy Lutomirski
2020-05-18 8:01 ` Peter Zijlstra
2020-05-18 8:05 ` Thomas Gleixner
2020-05-18 8:08 ` Peter Zijlstra
2020-05-20 20:09 ` Thomas Gleixner
2020-05-20 20:14 ` Andy Lutomirski
2020-05-20 22:20 ` Thomas Gleixner
2020-05-15 23:45 ` [patch V6 05/37] genirq: Provide irq_enter/exit_rcu() Thomas Gleixner
2020-05-18 23:06 ` Andy Lutomirski
2020-05-15 23:45 ` [patch V6 06/37] genirq: Provde __irq_enter/exit_raw() Thomas Gleixner
2020-05-18 23:07 ` Andy Lutomirski
2020-05-15 23:45 ` [patch V6 07/37] x86/entry: Provide helpers for execute on irqstack Thomas Gleixner
2020-05-18 23:11 ` Andy Lutomirski
2020-05-18 23:46 ` Andy Lutomirski
2020-05-18 23:53 ` Thomas Gleixner
2020-05-18 23:56 ` Andy Lutomirski
2020-05-20 12:35 ` Thomas Gleixner
2020-05-20 15:09 ` Andy Lutomirski
2020-05-20 15:27 ` Thomas Gleixner
2020-05-20 15:36 ` Andy Lutomirski
2020-05-18 23:51 ` Thomas Gleixner
2020-05-15 23:45 ` [patch V6 08/37] x86/entry/64: Move do_softirq_own_stack() to C Thomas Gleixner
2020-05-18 23:48 ` Andy Lutomirski
2020-05-15 23:45 ` [patch V6 09/37] x86/entry: Split idtentry_enter/exit() Thomas Gleixner
2020-05-18 23:49 ` Andy Lutomirski
2020-05-19 8:25 ` Thomas Gleixner
2020-05-15 23:45 ` [patch V6 10/37] x86/entry: Switch XEN/PV hypercall entry to IDTENTRY Thomas Gleixner
2020-05-19 17:06 ` Andy Lutomirski
2020-05-19 18:57 ` Thomas Gleixner
2020-05-19 19:44 ` Andy Lutomirski
2020-05-20 8:06 ` Jürgen Groß
2020-05-20 11:31 ` Andrew Cooper
2020-05-20 14:13 ` Thomas Gleixner
2020-05-20 15:16 ` Andy Lutomirski
2020-05-20 17:22 ` Andy Lutomirski
2020-05-20 19:16 ` Thomas Gleixner
2020-05-20 23:21 ` Andy Lutomirski
2020-05-21 10:45 ` Thomas Gleixner
2020-05-21 2:23 ` Boris Ostrovsky
2020-05-21 7:08 ` Thomas Gleixner
2020-05-15 23:45 ` [patch V6 11/37] x86/entry/64: Simplify idtentry_body Thomas Gleixner
2020-05-19 17:06 ` Andy Lutomirski
2020-05-15 23:45 ` [patch V6 12/37] x86/entry: Provide idtentry_entry/exit_cond_rcu() Thomas Gleixner
2020-05-19 17:08 ` Andy Lutomirski
2020-05-19 19:00 ` Thomas Gleixner
2020-05-19 20:20 ` Thomas Gleixner
2020-05-19 20:24 ` Andy Lutomirski
2020-05-19 21:20 ` Thomas Gleixner
2020-05-20 0:26 ` Andy Lutomirski
2020-05-20 2:23 ` Paul E. McKenney
2020-05-20 15:36 ` Andy Lutomirski
2020-05-20 16:51 ` Andy Lutomirski
2020-05-20 18:05 ` Paul E. McKenney
2020-05-20 19:49 ` Thomas Gleixner
2020-05-20 22:15 ` Paul E. McKenney
2020-05-20 23:25 ` Paul E. McKenney
2020-05-21 8:31 ` Thomas Gleixner
2020-05-21 13:39 ` Paul E. McKenney
2020-05-21 18:41 ` Thomas Gleixner
2020-05-21 19:04 ` Paul E. McKenney
2020-05-20 18:32 ` Thomas Gleixner
2020-05-20 19:24 ` Thomas Gleixner
2020-05-20 19:42 ` Paul E. McKenney
2020-05-20 17:38 ` Paul E. McKenney
2020-05-20 17:47 ` Andy Lutomirski
2020-05-20 18:11 ` Paul E. McKenney
2020-05-20 14:19 ` Thomas Gleixner
2020-05-27 8:12 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-15 23:46 ` [patch V6 13/37] x86/entry: Switch page fault exception to IDTENTRY_RAW Thomas Gleixner
2020-05-19 20:12 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 14/37] x86/entry: Remove the transition leftovers Thomas Gleixner
2020-05-19 20:13 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 15/37] x86/entry: Change exit path of xen_failsafe_callback Thomas Gleixner
2020-05-19 20:14 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 16/37] x86/entry/64: Remove error_exit Thomas Gleixner
2020-05-19 20:14 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 17/37] x86/entry/32: Remove common_exception Thomas Gleixner
2020-05-19 20:14 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 18/37] x86/irq: Use generic irq_regs implementation Thomas Gleixner
2020-05-15 23:46 ` [patch V6 19/37] x86/irq: Convey vector as argument and not in ptregs Thomas Gleixner
2020-05-19 20:19 ` Andy Lutomirski
2020-05-21 13:22 ` Thomas Gleixner
2020-05-22 18:48 ` Boris Ostrovsky
2020-05-22 19:26 ` Josh Poimboeuf
2020-05-22 19:54 ` Thomas Gleixner
2020-05-15 23:46 ` [patch V6 20/37] x86/irq/64: Provide handle_irq() Thomas Gleixner
2020-05-19 20:21 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 21/37] x86/entry: Add IRQENTRY_IRQ macro Thomas Gleixner
2020-05-19 20:27 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 22/37] x86/entry: Use idtentry for interrupts Thomas Gleixner
2020-05-19 20:28 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 23/37] x86/entry: Provide IDTENTRY_SYSVEC Thomas Gleixner
2020-05-20 0:29 ` Andy Lutomirski
2020-05-20 15:07 ` Thomas Gleixner
2020-05-15 23:46 ` [patch V6 24/37] x86/entry: Convert APIC interrupts to IDTENTRY_SYSVEC Thomas Gleixner
2020-05-20 0:27 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 25/37] x86/entry: Convert SMP system vectors " Thomas Gleixner
2020-05-20 0:28 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 26/37] x86/entry: Convert various system vectors Thomas Gleixner
2020-05-20 0:30 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 27/37] x86/entry: Convert KVM vectors to IDTENTRY_SYSVEC Thomas Gleixner
2020-05-20 0:30 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 28/37] x86/entry: Convert various hypervisor " Thomas Gleixner
2020-05-20 0:31 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 29/37] x86/entry: Convert XEN hypercall vector " Thomas Gleixner
2020-05-20 0:31 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 30/37] x86/entry: Convert reschedule interrupt to IDTENTRY_RAW Thomas Gleixner
2020-05-19 23:57 ` Andy Lutomirski
2020-05-20 15:08 ` Thomas Gleixner
2020-05-15 23:46 ` [patch V6 31/37] x86/entry: Remove the apic/BUILD interrupt leftovers Thomas Gleixner
2020-05-20 0:32 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 32/37] x86/entry/64: Remove IRQ stack switching ASM Thomas Gleixner
2020-05-20 0:33 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 33/37] x86/entry: Make enter_from_user_mode() static Thomas Gleixner
2020-05-20 0:34 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 34/37] x86/entry/32: Remove redundant irq disable code Thomas Gleixner
2020-05-20 0:35 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 35/37] x86/entry/64: Remove TRACE_IRQS_*_DEBUG Thomas Gleixner
2020-05-20 0:46 ` Andy Lutomirski
2020-05-15 23:46 ` [patch V6 36/37] x86/entry: Move paranoid irq tracing out of ASM code Thomas Gleixner
2020-05-20 0:53 ` Andy Lutomirski
2020-05-20 15:16 ` Thomas Gleixner
2020-05-20 17:13 ` Andy Lutomirski
2020-05-20 18:33 ` Thomas Gleixner
2020-05-15 23:46 ` [patch V6 37/37] x86/entry: Remove the TRACE_IRQS cruft Thomas Gleixner
2020-05-18 23:07 ` Andy Lutomirski
2020-05-16 17:18 ` [patch V6 00/37] x86/entry: Rework leftovers and merge plan Paul E. McKenney
2020-05-19 12:28 ` Joel Fernandes
2020-05-18 16:07 ` Peter Zijlstra
2020-05-18 18:53 ` Thomas Gleixner
2020-05-19 8:29 ` Peter Zijlstra
2020-05-18 20:24 ` Thomas Gleixner
2020-05-19 8:38 ` Peter Zijlstra
2020-05-19 9:02 ` Peter Zijlstra
2020-05-23 2:52 ` Lai Jiangshan
2020-05-23 13:08 ` Peter Zijlstra
2020-06-15 16:17 ` Peter Zijlstra
2020-05-19 9:06 ` Thomas Gleixner
2020-05-19 18:37 ` Steven Rostedt
2020-05-19 19:09 ` Thomas Gleixner
2020-05-19 19:13 ` Steven Rostedt
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