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From: Steven Rostedt <rostedt@goodmis.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
	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>,
	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>
Subject: Re: [patch V4 part 2 10/18] x86/entry/64: Check IF in __preempt_enable_notrace() thunk
Date: Mon, 11 May 2020 21:51:08 -0400	[thread overview]
Message-ID: <20200511215108.3ccea526@oasis.local.home> (raw)
In-Reply-To: <20200505134341.087595319@linutronix.de>

[-- Attachment #1: Type: text/plain, Size: 1150 bytes --]

On Tue, 05 May 2020 15:41:22 +0200
Thomas Gleixner <tglx@linutronix.de> wrote:

> The preempt_enable_notrace() ASM thunk is called from tracing, entry code
> RCU and other places which are already in or going to be in the noinstr
> section which protects sensitve code from being instrumented.
> 
> Calls out of these sections happen with interrupts disabled, which is
> handled in C code, but the push regs, call, pop regs sequence can be
> completely avoided in this case.
> 
> This is also a preparatory step for annotating the call from the thunk to
> preempt_enable_notrace() safe from a noinstr section.
> 

BTW, after applying this patch, I get the following error:

/work/git/linux-test.git/arch/x86/entry/thunk_64.S: Assembler messages:
/work/git/linux-test.git/arch/x86/entry/thunk_64.S:67: Error: invalid operands (*UND* and *UND* sections) for `+'
/work/git/linux-test.git/arch/x86/entry/thunk_64.S:67: Error: invalid operands (*UND* and *ABS* sections) for `/'
make[3]: *** [/work/git/linux-test.git/scripts/Makefile.build:349: arch/x86/entry/thunk_64.o] Error 1
make[3]: *** Waiting for unfinished jobs....

Config attached.

-- Steve


[-- Attachment #2: config.gz --]
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  parent reply	other threads:[~2020-05-12  1:51 UTC|newest]

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-05 13:41 [patch V4 part 2 00/18] x86/entry: Entry/exception code rework, syscall and KVM changes Thomas Gleixner
2020-05-05 13:41 ` [patch V4 part 2 01/18] x86/entry/64: Move non entry code into .text section Thomas Gleixner
2020-05-06 15:51   ` Peter Zijlstra
2020-05-08  1:31   ` Steven Rostedt
2020-05-08 23:53   ` Andy Lutomirski
2020-05-10 13:39     ` Thomas Gleixner
2020-05-19 19:58   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:41 ` [patch V4 part 2 02/18] x86/entry/32: " Thomas Gleixner
2020-05-07 13:15   ` Alexandre Chartre
2020-05-07 14:14     ` Thomas Gleixner
2020-05-19 19:58   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:41 ` [patch V4 part 2 03/18] x86/entry: Mark enter_from_user_mode() noinstr Thomas Gleixner
2020-05-08  8:21   ` Masami Hiramatsu
2020-05-19 19:58   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:41 ` [patch V4 part 2 04/18] x86/entry/common: Protect against instrumentation Thomas Gleixner
2020-05-07 13:39   ` Alexandre Chartre
2020-05-07 14:13     ` Thomas Gleixner
2020-05-19 19:58   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:41 ` [patch V4 part 2 05/18] x86/entry: Move irq tracing on syscall entry to C-code Thomas Gleixner
2020-05-07 13:55   ` Alexandre Chartre
2020-05-07 14:10     ` Thomas Gleixner
2020-05-07 15:03       ` Thomas Gleixner
2020-05-07 17:06         ` Thomas Gleixner
2020-05-19 19:58   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:41 ` [patch V4 part 2 06/18] x86/entry: Move irq flags tracing to prepare_exit_to_usermode() Thomas Gleixner
2020-05-08 23:57   ` Andy Lutomirski
2020-05-09 10:16     ` Thomas Gleixner
2020-05-19 19:58   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:41 ` [patch V4 part 2 07/18] context_tracking: Ensure that the critical path cannot be instrumented Thomas Gleixner
2020-05-08  8:23   ` Masami Hiramatsu
2020-05-19 19:58   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:41 ` [patch V4 part 2 08/18] lib/smp_processor_id: Move it into noinstr section Thomas Gleixner
2020-05-19 19:58   ` [tip: x86/entry] x86/speculation/mds: Mark mds_user_clear_cpu_buffers() __always_inline tip-bot2 for Thomas Gleixner
2020-05-19 19:58   ` [tip: x86/entry] lib/smp_processor_id: Move it into noinstr section tip-bot2 for Thomas Gleixner
2020-05-05 13:41 ` [patch V4 part 2 09/18] x86/speculation/mds: Mark mds_user_clear_cpu_buffers() __always_inline Thomas Gleixner
2020-05-05 13:41 ` [patch V4 part 2 10/18] x86/entry/64: Check IF in __preempt_enable_notrace() thunk Thomas Gleixner
2020-05-07 14:15   ` Alexandre Chartre
2020-05-09  0:10   ` Andy Lutomirski
2020-05-09 10:25     ` Thomas Gleixner
2020-05-10 18:47       ` Thomas Gleixner
2020-05-11 18:27         ` Thomas Gleixner
2020-05-12  1:48     ` Steven Rostedt
2020-05-12  1:51   ` Steven Rostedt [this message]
2020-05-12  8:14     ` Thomas Gleixner
2020-05-05 13:41 ` [patch V4 part 2 11/18] x86/entry/64: Mark ___preempt_schedule_notrace() thunk noinstr Thomas Gleixner
2020-05-05 13:41 ` [patch V4 part 2 12/18] x86,objtool: Make entry_64_compat.S objtool clean Thomas Gleixner
2020-05-09  0:11   ` Andy Lutomirski
2020-05-09 10:06     ` Thomas Gleixner
2020-05-19 19:58   ` [tip: x86/entry] x86/entry: " tip-bot2 for Peter Zijlstra
2020-05-05 13:41 ` [patch V4 part 2 13/18] x86/kvm: Move context tracking where it belongs Thomas Gleixner
2020-05-06  7:42   ` Paolo Bonzini
2020-05-09  0:14   ` Andy Lutomirski
2020-05-09 10:12     ` Thomas Gleixner
2020-05-05 13:41 ` [patch V4 part 2 14/18] x86/kvm/vmx: Add hardirq tracing to guest enter/exit Thomas Gleixner
2020-05-06  7:55   ` Paolo Bonzini
2020-05-05 13:41 ` [patch V4 part 2 15/18] x86/kvm/svm: Handle hardirqs proper on " Thomas Gleixner
2020-05-06  8:15   ` Paolo Bonzini
2020-05-06  8:48     ` Thomas Gleixner
2020-05-06  9:21       ` Paolo Bonzini
2020-05-07 14:44         ` [patch V5 " Thomas Gleixner
2020-05-08 13:45           ` Paolo Bonzini
2020-05-08 14:01             ` Thomas Gleixner
2020-05-05 13:41 ` [patch V4 part 2 16/18] context_tracking: Make guest_enter/exit() .noinstr ready Thomas Gleixner
2020-05-19 19:58   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:41 ` [patch V4 part 2 17/18] x86/kvm/vmx: Move guest enter/exit into .noinstr.text Thomas Gleixner
2020-05-06  8:17   ` Paolo Bonzini
2020-05-05 13:41 ` [patch V4 part 2 18/18] x86/kvm/svm: " Thomas Gleixner
2020-05-06  8:17   ` Paolo Bonzini
2020-05-07 14:47   ` Alexandre Chartre

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