From: Andy Lutomirski <luto@amacapital.net>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
Andy Lutomirski <luto@kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>,
paulmck <paulmck@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, Google" <joel@joelfernandes.org>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Juergen Gross <JGross@suse.com>, Brian Gerst <brgerst@gmail.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Will Deacon <will@kernel.org>
Subject: Re: [patch V4 part 3 01/29] x86/traps: Mark fixup_bad_iret() noinstr
Date: Wed, 13 May 2020 18:35:40 -0700 [thread overview]
Message-ID: <DBE4DB85-973F-4E16-8574-B93F9E4A51BC@amacapital.net> (raw)
In-Reply-To: <807929267.20601.1589416908153.JavaMail.zimbra@efficios.com>
> On May 13, 2020, at 5:41 PM, Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
>
> ----- On May 12, 2020, at 9:51 PM, rostedt rostedt@goodmis.org wrote:
>
>>> On Fri, 8 May 2020 17:39:00 -0700
>>> Andy Lutomirski <luto@kernel.org> wrote:
>>>
>>> On Tue, May 5, 2020 at 7:15 AM Thomas Gleixner <tglx@linutronix.de> wrote:
>>>>
>>>> This is called from deep entry ASM in a situation where instrumentation
>>>> will cause more harm than providing useful information.
>>>>
>>>
>>> Acked-by: Andy Lutomirski <luto@kernel.org>
>>>
>>> Maybe add to changelog:
>>>
>>> Switch from memmove() to memcpy() because memmove() can't be called
>>> from noinstr code.
>>
>> Yes please, because I was about to say that there was changes that
>> didn't seem to fit the change log.
>>
>> I would also add a comment in the code saying that we need the temp
>> variable to use memcpy as memmove can't be used in noinstr code.
>
> Looking at an updated version of the tree, I see the acked-by from Andy,
> but not comment about switching from memmove to memcpy.
>
> Also, I notice a significant undocumented change in this patch: it changes
> a this_cpu_read() (which presumes preemption is enabled) to a __this_cpu_read().
>
> So the 100$ question: is preemption enabled or not in fixup_bad_iret() ? And of
> course that change should be documented in the commit message.
>
IRQs are off, and, if they were on, the lack of a warning from the percpu access would be the least of our concerns here.
> Thanks,
>
> Mathieu
>
> --
> Mathieu Desnoyers
> EfficiOS Inc.
> http://www.efficios.com
next prev parent reply other threads:[~2020-05-14 1:35 UTC|newest]
Thread overview: 129+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-05 13:43 [patch V4 part 3 00/29] x86/entry: Entry/exception code rework, simple exceptions Thomas Gleixner
2020-05-05 13:43 ` [patch V4 part 3 01/29] x86/traps: Mark fixup_bad_iret() noinstr Thomas Gleixner
2020-05-09 0:39 ` Andy Lutomirski
2020-05-13 1:51 ` Steven Rostedt
2020-05-14 0:41 ` Mathieu Desnoyers
2020-05-14 1:35 ` Andy Lutomirski [this message]
2020-05-11 12:28 ` Masami Hiramatsu
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:43 ` [patch V4 part 3 02/29] x86/traps: Mark sync_regs() noinstr Thomas Gleixner
2020-05-09 0:39 ` Andy Lutomirski
2020-05-11 12:08 ` Masami Hiramatsu
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:43 ` [patch V4 part 3 03/29] x86/entry: Disable interrupts for native_load_gs_index() in C code Thomas Gleixner
2020-05-09 0:40 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:43 ` [patch V4 part 3 04/29] x86/traps: Make interrupt enable/disable symmetric " Thomas Gleixner
2020-05-07 15:25 ` Alexandre Chartre
2020-05-07 17:14 ` Thomas Gleixner
2020-05-09 0:44 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:43 ` [patch V4 part 3 05/29] x86/traps: Split trap numbers out in a seperate header Thomas Gleixner
2020-05-07 15:34 ` Alexandre Chartre
2020-05-19 19:58 ` [tip: x86/entry] x86/traps: Split trap numbers out in a separate header tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 06/29] x86/entry/64: Reorder idtentries Thomas Gleixner
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 07/29] x86/entry: Distangle idtentry Thomas Gleixner
2020-05-10 20:31 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 08/29] x86/entry/64: Provide sane error entry/exit Thomas Gleixner
2020-05-10 21:02 ` Andy Lutomirski
2020-05-13 2:10 ` Steven Rostedt
2020-05-13 6:35 ` Thomas Gleixner
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 09/29] x86/entry/32: Provide macro to emit IDT entry stubs Thomas Gleixner
2020-05-11 0:55 ` Andy Lutomirski
2020-05-14 1:44 ` Mathieu Desnoyers
2020-05-14 4:31 ` Andy Lutomirski
2020-05-14 13:38 ` Mathieu Desnoyers
2020-05-14 14:08 ` Thomas Gleixner
2020-05-14 14:43 ` Mathieu Desnoyers
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 10/29] x86/idtentry: Provide macros to define/declare IDT entry points Thomas Gleixner
2020-05-11 0:58 ` Andy Lutomirski
2020-05-11 10:39 ` Thomas Gleixner
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 11/29] rcu: Provide rcu_irq_exit_preempt() Thomas Gleixner
2020-05-05 22:02 ` Paul E. McKenney
2020-05-05 22:05 ` Thomas Gleixner
2020-05-05 22:24 ` Paul E. McKenney
2020-05-14 1:03 ` Mathieu Desnoyers
2020-05-14 2:41 ` Joel Fernandes
2020-05-14 2:46 ` Joel Fernandes
2020-05-14 14:43 ` Thomas Gleixner
2020-05-15 19:00 ` Joel Fernandes
2020-05-19 19:52 ` [tip: core/rcu] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 12/29] x86/entry/common: Provide idtentry_enter/exit() Thomas Gleixner
2020-05-07 16:27 ` Alexandre Chartre
2020-05-11 4:34 ` Andy Lutomirski
2020-05-11 10:59 ` [patch V5 " Thomas Gleixner
2020-05-11 15:31 ` Andy Lutomirski
2020-05-11 18:42 ` Thomas Gleixner
2020-05-12 16:49 ` [patch V6 " Thomas Gleixner
2020-05-14 0:51 ` Andy Lutomirski
2020-05-14 1:08 ` [patch V4 " Mathieu Desnoyers
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 13/29] x86/traps: Prepare for using DEFINE_IDTENTRY Thomas Gleixner
2020-05-14 4:37 ` Andy Lutomirski
2020-05-14 12:16 ` Thomas Gleixner
2020-05-14 12:33 ` Peter Zijlstra
2020-05-15 13:42 ` Thomas Gleixner
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 14/29] x86/entry: Convert Divide Error to IDTENTRY Thomas Gleixner
2020-05-14 4:38 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-10-11 15:25 ` Dmitry Vyukov
2020-10-11 17:50 ` Thomas Gleixner
2020-10-12 13:19 ` [tip: x86/urgent] x86/traps: Fix #DE Oops message regression tip-bot2 for Thomas Gleixner
2020-10-12 20:30 ` [tip: x86/entry] x86/entry: Convert Divide Error to IDTENTRY Kees Cook
2020-10-13 10:19 ` Dmitry Vyukov
2020-10-13 17:41 ` [tip: x86/urgent] x86/traps: Fix #DE Oops message regression tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 15/29] x86/entry: Convert Overflow exception to IDTENTRY Thomas Gleixner
2020-05-14 4:39 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 16/29] x86/entry: Convert Bounds " Thomas Gleixner
2020-05-14 4:42 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 17/29] x86/entry: Convert Invalid Opcode " Thomas Gleixner
2020-05-14 4:45 ` Andy Lutomirski
2020-05-14 12:33 ` Thomas Gleixner
2020-05-14 15:00 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 18/29] x86/entry: Convert Device not available " Thomas Gleixner
2020-05-14 4:45 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 19/29] x86/entry: Convert Coprocessor segment overrun " Thomas Gleixner
2020-05-14 4:46 ` Andy Lutomirski
2020-05-05 13:44 ` [patch V4 part 3 20/29] x86/entry: Provide IDTENTRY_ERRORCODE Thomas Gleixner
2020-05-14 4:46 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] x86/idtentry: " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 21/29] x86/entry: Convert Invalid TSS exception to IDTENTRY Thomas Gleixner
2020-05-14 4:48 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 22/29] x86/entry: Convert Segment not present " Thomas Gleixner
2020-05-14 4:47 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 23/29] x86/entry: Convert Stack segment " Thomas Gleixner
2020-05-14 4:49 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 24/29] x86/entry: Convert General protection " Thomas Gleixner
2020-05-14 4:50 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 25/29] x86/entry: Convert Spurious interrupt bug " Thomas Gleixner
2020-05-14 4:47 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 26/29] x86/entry: Convert Coprocessor error " Thomas Gleixner
2020-05-14 4:49 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-19 19:58 ` [tip: x86/entry] x86/entry: Convert Coprocessor segment overrun " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 27/29] x86/entry: Convert Alignment check " Thomas Gleixner
2020-05-14 4:50 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 28/29] x86/entry: Convert SIMD coprocessor error " Thomas Gleixner
2020-05-14 4:56 ` Andy Lutomirski
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:44 ` [patch V4 part 3 29/29] x86/entry/32: Convert IRET exception to IDTENTRY_SW Thomas Gleixner
2020-05-07 16:47 ` Alexandre Chartre
2020-05-14 4:54 ` Andy Lutomirski
2020-05-15 14:11 ` Thomas Gleixner
2020-05-19 19:58 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
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