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From: Thomas Gleixner <tglx@linutronix.de>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	x86@kernel.org, Kees Cook <keescook@chromium.org>
Subject: Re: [patch 05/12] x86/irq: Provide macro for inlining irq stack switching
Date: Tue, 09 Feb 2021 16:12:33 +0100	[thread overview]
Message-ID: <87zh0db7ha.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20210208204209.yccd76j7sp2zbv37@treble>

On Mon, Feb 08 2021 at 14:42, Josh Poimboeuf wrote:
> On Thu, Feb 04, 2021 at 09:49:08PM +0100, Thomas Gleixner wrote:
>>  #ifdef CONFIG_X86_64
>> +
>> +#ifdef CONFIG_UNWINDER_FRAME_POINTER
>> +# define IRQSTACK_CALL_CONSTRAINT	, ASM_CALL_CONSTRAINT
>> +#else
>> +# define IRQSTACK_CALL_CONSTRAINT
>> +#endif
>
> Is this really needed?  i.e. does ASM_CALL_CONSTRAINT actually affect
> code generation with !FRAME_POINTER?

The problem is that if the asm inline is the first operation in a
function some compilers insert the asm inline before setting up the
frame pointer.

That's actualy irrelevant here as the compiler cannot reorder against
the C code leading to the asm inline. So we can probably replace it with
a big fat comment.

Thanks,

        tglx







  reply	other threads:[~2021-02-09 15:13 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-04 20:49 [patch 00/12] x86/irq/64: Inline irq stack switching Thomas Gleixner
2021-02-04 20:49 ` [patch 01/12] x86/entry: Fix instrumentation annotation Thomas Gleixner
2021-02-05 12:02   ` Borislav Petkov
2021-02-04 20:49 ` [patch 02/12] x86/irq: Sanitize irq stack tracking Thomas Gleixner
2021-02-04 20:49 ` [patch 03/12] x86/irq/64: Adjust the per CPU irq stack pointer by 8 Thomas Gleixner
2021-02-05 13:53   ` Peter Zijlstra
2021-02-05 15:00     ` Thomas Gleixner
2021-02-04 20:49 ` [patch 04/12] x86/apic: Split out spurious handling code Thomas Gleixner
2021-02-04 20:49 ` [patch 05/12] x86/irq: Provide macro for inlining irq stack switching Thomas Gleixner
2021-02-08 15:06   ` Borislav Petkov
2021-02-08 20:42   ` Josh Poimboeuf
2021-02-09 15:12     ` Thomas Gleixner [this message]
2021-02-09 16:22       ` Josh Poimboeuf
2021-02-09 18:14         ` Thomas Gleixner
2021-02-04 20:49 ` [patch 06/12] x86/entry: Convert system vectors to irq stack macro Thomas Gleixner
2021-02-05  3:52   ` kernel test robot
2021-02-05 14:13     ` Peter Zijlstra
2021-02-07  8:15       ` [kbuild-all] " Rong Chen
2021-02-08 14:19         ` Borislav Petkov
2021-02-09  8:57           ` Rong Chen
2021-02-09 10:46             ` Borislav Petkov
2021-02-04 20:49 ` [patch 07/12] x86/entry: Convert device interrupts to inline stack switching Thomas Gleixner
2021-02-04 20:49 ` [patch 08/12] x86/entry: Use run_sysvec_on_irqstack_cond() for XEN upcall Thomas Gleixner
2021-02-05  7:28   ` kernel test robot
2021-02-04 20:49 ` [patch 09/12] x86/softirq: Remove indirection in do_softirq_own_stack() Thomas Gleixner
2021-02-04 20:49 ` [patch 10/12] x86: Select CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK Thomas Gleixner
2021-02-04 20:49 ` [patch 11/12] softirq: Allow inlining do_softirq_own_stack() Thomas Gleixner
2021-02-05 10:14   ` Lai Jiangshan
2021-02-05 11:38     ` Thomas Gleixner
2021-02-09 20:43       ` Thomas Gleixner
2021-02-04 20:49 ` [patch 12/12] x86/softirq/64: Inline do_softirq_own_stack() Thomas Gleixner
2021-02-08 21:47 ` [patch 00/12] x86/irq/64: Inline irq stack switching Kees Cook
2021-02-05 11:03 [patch 05/12] x86/irq: Provide macro for inlining " Uros Bizjak
2021-02-05 13:24 ` Thomas Gleixner

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