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 13/13] x86/entry/common: Split irq tracing in prepare_exit_to_usermode()
Date: Tue, 10 Mar 2020 15:09:31 +0100 [thread overview]
Message-ID: <d01a2ab6-db0f-cc0e-83e1-a60d95cde8e9@oracle.com> (raw)
In-Reply-To: <20200308222610.245444311@linutronix.de>
On 3/8/20 11:24 PM, Thomas Gleixner wrote:
> As in entry from user mode, lockdep and tracing have different
> requirements. lockdep needs to know about the interrupts off state accross
> the call to user_enter_irqsoff() but tracing is unsafe after the call.
typo: user_enter_irqoff() (no 's' between 'irq' and 'off').
>
> Split it up and tell the tracer that interrupts are going to be enabled
> before calling user_enter_irqsoff() and tell lockdep afterwards.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> arch/x86/entry/common.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> --- a/arch/x86/entry/common.c
> +++ b/arch/x86/entry/common.c
> @@ -251,9 +251,19 @@ static noinline void __prepare_exit_to_u
> {
> __prepare_exit_to_usermode(regs);
>
> + /*
> + * Return to user space enables interrupts. Tell the tracer before
> + * invoking user_enter_irqsoff() which switches to CONTEXT_USER and
Same typo here: user_enter_irqoff()
> + * RCU to rcuidle state. Lockdep still needs to keep the irqs
> + * disabled state.
> + */
> + __trace_hardirqs_on();
> +
> user_enter_irqoff();
> mds_user_clear_cpu_buffers();
> - trace_hardirqs_on();
> +
> + /* All done. Tell lockdep as well. */
> + lockdep_hardirqs_on(CALLER_ADDR0);
> }
> NOKPROBE_SYMBOL(prepare_exit_to_usermode);
>
>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
alex.
prev parent reply other threads:[~2020-03-10 14:10 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
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 [this message]
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