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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Steven Rostedt <rostedt@goodmis.org>,
	Brian Gerst <brgerst@gmail.com>, Juergen Gross <jgross@suse.com>,
	Frederic Weisbecker <frederic@kernel.org>,
	Alexandre Chartre <alexandre.chartre@oracle.com>
Subject: [patch part-II V2 08/13] tracing: Provide lockdep less trace_hardirqs_on/off() variants
Date: Sun, 08 Mar 2020 23:24:07 +0100	[thread overview]
Message-ID: <20200308222609.731890049@linutronix.de> (raw)
In-Reply-To: 20200308222359.370649591@linutronix.de

trace_hardirqs_on/off() is only partially safe vs. RCU idle. The tracer
core itself is safe, but the resulting tracepoints can be utilized by
e.g. BPF which is unsafe.

Provide variants which do not contain the lockdep invocation so the lockdep
and tracer invocations can be split at the call site and placed properly.

The new variants also do not use rcuidle as they are going to be called
from entry code after/before context tracking.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
V2: New patch
---
 include/linux/irqflags.h        |    4 ++++
 kernel/trace/trace_preemptirq.c |   23 +++++++++++++++++++++++
 2 files changed, 27 insertions(+)

--- a/include/linux/irqflags.h
+++ b/include/linux/irqflags.h
@@ -29,6 +29,8 @@
 #endif
 
 #ifdef CONFIG_TRACE_IRQFLAGS
+  extern void __trace_hardirqs_on(void);
+  extern void __trace_hardirqs_off(void);
   extern void trace_hardirqs_on(void);
   extern void trace_hardirqs_off(void);
 # define trace_hardirq_context(p)	((p)->hardirq_context)
@@ -52,6 +54,8 @@ do {						\
 	current->softirq_context--;		\
 } while (0)
 #else
+# define __trace_hardirqs_on()		do { } while (0)
+# define __trace_hardirqs_off()		do { } while (0)
 # define trace_hardirqs_on()		do { } while (0)
 # define trace_hardirqs_off()		do { } while (0)
 # define trace_hardirq_context(p)	0
--- a/kernel/trace/trace_preemptirq.c
+++ b/kernel/trace/trace_preemptirq.c
@@ -19,6 +19,17 @@
 /* Per-cpu variable to prevent redundant calls when IRQs already off */
 static DEFINE_PER_CPU(int, tracing_irq_cpu);
 
+void __trace_hardirqs_on(void)
+{
+	if (this_cpu_read(tracing_irq_cpu)) {
+		if (!in_nmi())
+			trace_irq_enable(CALLER_ADDR0, CALLER_ADDR1);
+		tracer_hardirqs_on(CALLER_ADDR0, CALLER_ADDR1);
+		this_cpu_write(tracing_irq_cpu, 0);
+	}
+}
+NOKPROBE_SYMBOL(__trace_hardirqs_on);
+
 void trace_hardirqs_on(void)
 {
 	if (this_cpu_read(tracing_irq_cpu)) {
@@ -33,6 +44,18 @@ void trace_hardirqs_on(void)
 EXPORT_SYMBOL(trace_hardirqs_on);
 NOKPROBE_SYMBOL(trace_hardirqs_on);
 
+void __trace_hardirqs_off(void)
+{
+	if (!this_cpu_read(tracing_irq_cpu)) {
+		this_cpu_write(tracing_irq_cpu, 1);
+		tracer_hardirqs_off(CALLER_ADDR0, CALLER_ADDR1);
+		if (!in_nmi())
+			trace_irq_disable(CALLER_ADDR0, CALLER_ADDR1);
+	}
+
+}
+NOKPROBE_SYMBOL(__trace_hardirqs_off);
+
 void trace_hardirqs_off(void)
 {
 	if (!this_cpu_read(tracing_irq_cpu)) {


  parent reply	other threads:[~2020-03-08 23:24 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-08 22:23 [patch part-II V2 00/13] x86/entry: Consolidation - Part II (syscalls) Thomas Gleixner
2020-03-08 22:24 ` [patch part-II V2 01/13] context_tracking: Ensure that the critical path cannot be instrumented Thomas Gleixner
2020-03-09 14:22   ` Frederic Weisbecker
2020-03-09 14:40     ` Thomas Gleixner
2020-03-10 10:12   ` Alexandre Chartre
2020-03-08 22:24 ` [patch part-II V2 02/13] x86/entry: Mark enter_from_user_mode() notrace and NOKPROBE Thomas Gleixner
2020-03-09 15:14   ` Frederic Weisbecker
2020-03-09 15:40     ` Thomas Gleixner
2020-03-11 22:21       ` Frederic Weisbecker
2020-03-10 10:15   ` Alexandre Chartre
2020-03-08 22:24 ` [patch part-II V2 03/13] x86/entry/32: Remove unused label restore_nocheck Thomas Gleixner
2020-03-10 10:16   ` Alexandre Chartre
2020-03-10 13:02   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-03-08 22:24 ` [patch part-II V2 04/13] x86/entry/64: Trace irqflags unconditionally as ON when returning to user space Thomas Gleixner
2020-03-10 10:25   ` Alexandre Chartre
2020-03-10 13:02   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-03-08 22:24 ` [patch part-II V2 05/13] x86/entry/common: Consolidate syscall entry code Thomas Gleixner
2020-03-08 22:24 ` [patch part-II V2 06/13] x86/entry/common: Mark syscall entry points notrace and NOKPROBE Thomas Gleixner
2020-03-13 15:12   ` Frederic Weisbecker
2020-03-08 22:24 ` [patch part-II V2 07/13] x86/entry: Move irq tracing on syscall entry to C-code Thomas Gleixner
2020-03-13 15:16   ` Frederic Weisbecker
2020-03-13 23:17     ` Thomas Gleixner
2020-03-08 22:24 ` Thomas Gleixner [this message]
2020-03-10 10:55   ` [patch part-II V2 08/13] tracing: Provide lockdep less trace_hardirqs_on/off() variants Alexandre Chartre
2020-03-10 11:08     ` Borislav Petkov
2020-03-10 11:21       ` Alexandre Chartre
2020-03-08 22:24 ` [patch part-II V2 09/13] x86/entry/common: Split hardirq tracing into lockdep and ftrace parts Thomas Gleixner
2020-03-10 11:20   ` Borislav Petkov
2020-03-10 13:40     ` Steven Rostedt
2020-03-10 13:28   ` Alexandre Chartre
2020-03-23  9:08   ` [x86/entry/common] bae397f6e7: WARNING:at_kernel/sched/cputime.c:#get_vtime_delta kernel test robot
2020-03-08 22:24 ` [patch part-II V2 10/13] x86/entry/common: Split prepare_exit_to_usermode() and syscall_return_slowpath() Thomas Gleixner
2020-03-10 13:37   ` Alexandre Chartre
2020-03-08 22:24 ` [patch part-II V2 11/13] x86/speculation/mds: Mark mds_user_clear_cpu_buffers() __always_inline Thomas Gleixner
2020-03-10 13:48   ` Alexandre Chartre
2020-03-10 16:38     ` Thomas Gleixner
2020-03-08 22:24 ` [patch part-II V2 12/13] x86/entry: Move irq flags tracing to prepare_exit_to_usermode() Thomas Gleixner
2020-03-10 14:03   ` Alexandre Chartre
2020-03-08 22:24 ` [patch part-II V2 13/13] x86/entry/common: Split irq tracing in prepare_exit_to_usermode() Thomas Gleixner
2020-03-10 14:09   ` Alexandre Chartre

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