From: Alexandre Chartre <alexandre.chartre@oracle.com>
To: Thomas Gleixner <tglx@linutronix.de>,
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>
Subject: Re: [patch part-II V2 08/13] tracing: Provide lockdep less trace_hardirqs_on/off() variants
Date: Tue, 10 Mar 2020 11:55:57 +0100 [thread overview]
Message-ID: <07a50582-1c2f-7f45-c7dd-5ff9c2ff3052@oracle.com> (raw)
In-Reply-To: <20200308222609.731890049@linutronix.de>
On 3/8/20 11:24 PM, Thomas Gleixner wrote:
> 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);
> +
Shouldn't trace_hardirqs_on() be updated to call __trace_hardirqs_on()? It's the same
code except for the lockdep call.
void trace_hardirqs_on(void)
{
__trace_hardirqs_on();
lockdep_hardirqs_on(CALLER_ADDR0);
}
EXPORT_SYMBOL(trace_hardirqs_on);
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);
> +
Same comment here.
alex.
> void trace_hardirqs_off(void)
> {
> if (!this_cpu_read(tracing_irq_cpu)) {
>
next prev parent reply other threads:[~2020-03-10 10:56 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 ` [patch part-II V2 08/13] tracing: Provide lockdep less trace_hardirqs_on/off() variants Thomas Gleixner
2020-03-10 10:55 ` Alexandre Chartre [this message]
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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