From: "Jürgen Groß" <jgross@suse.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
"VMware, Inc." <pv-drivers@vmware.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
luto@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
xen-devel@lists.xenproject.org,
Thomas Gleixner <tglx@linutronix.de>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [PATCH v2 05/12] x86: rework arch_local_irq_restore() to not use popf
Date: Sun, 22 Nov 2020 07:55:55 +0100 [thread overview]
Message-ID: <eb05e878-6334-8d19-496b-6572df67fc56@suse.com> (raw)
In-Reply-To: <20201120115943.GD3021@hirez.programming.kicks-ass.net>
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On 20.11.20 12:59, Peter Zijlstra wrote:
> On Fri, Nov 20, 2020 at 12:46:23PM +0100, Juergen Gross wrote:
>> +static __always_inline void arch_local_irq_restore(unsigned long flags)
>> +{
>> + if (!arch_irqs_disabled_flags(flags))
>> + arch_local_irq_enable();
>> +}
>
> If someone were to write horrible code like:
>
> local_irq_disable();
> local_irq_save(flags);
> local_irq_enable();
> local_irq_restore(flags);
>
> we'd be up some creek without a paddle... now I don't _think_ we have
> genius code like that, but I'd feel saver if we can haz an assertion in
> there somewhere...
>
> Maybe something like:
>
> #ifdef CONFIG_DEBUG_ENTRY // for lack of something saner
> WARN_ON_ONCE((arch_local_save_flags() ^ flags) & X86_EFLAGS_IF);
> #endif
>
> At the end?
I'd like to, but using WARN_ON_ONCE() in include/asm/irqflags.h sounds
like a perfect receipt for include dependency hell.
We could use a plain asm("ud2") instead.
Juergen
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next prev parent reply other threads:[~2020-11-22 6:56 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-20 11:46 [PATCH v2 00/12] x86: major paravirt cleanup Juergen Gross
2020-11-20 11:46 ` [PATCH v2 01/12] x86/xen: use specific Xen pv interrupt entry for MCE Juergen Gross
2020-12-09 21:03 ` Thomas Gleixner
2020-11-20 11:46 ` [PATCH v2 02/12] x86/xen: use specific Xen pv interrupt entry for DF Juergen Gross
2020-12-09 21:03 ` Thomas Gleixner
2020-11-20 11:46 ` [PATCH v2 03/12] x86/pv: switch SWAPGS to ALTERNATIVE Juergen Gross
2020-11-27 11:31 ` Borislav Petkov
2020-12-09 21:07 ` Thomas Gleixner
2020-11-20 11:46 ` [PATCH v2 04/12] x86/xen: drop USERGS_SYSRET64 paravirt call Juergen Gross
2020-12-02 12:32 ` Borislav Petkov
2020-12-02 14:48 ` Jürgen Groß
2020-12-02 17:08 ` Borislav Petkov
2020-11-20 11:46 ` [PATCH v2 05/12] x86: rework arch_local_irq_restore() to not use popf Juergen Gross
2020-11-20 11:59 ` Peter Zijlstra
2020-11-20 12:05 ` Jürgen Groß
2020-11-22 6:55 ` Jürgen Groß [this message]
2020-11-22 21:44 ` Andy Lutomirski
2020-11-23 5:21 ` Jürgen Groß
2020-11-23 15:15 ` Andy Lutomirski
2020-12-09 13:27 ` Mark Rutland
2020-12-09 14:02 ` Mark Rutland
2020-12-09 14:05 ` Jürgen Groß
2020-12-09 18:15 ` Mark Rutland
2020-12-09 18:54 ` Thomas Gleixner
2020-12-10 11:10 ` Mark Rutland
2020-12-10 20:15 ` x86/ioapic: Cleanup the timer_works() irqflags mess Thomas Gleixner
2020-12-11 5:10 ` Jürgen Groß
2020-11-27 2:20 ` [x86] 97e8f0134a: fio.write_iops 8.6% improvement kernel test robot
2020-11-20 11:46 ` [PATCH v2 06/12] x86/paravirt: switch time pvops functions to use static_call() Juergen Gross
2020-11-20 12:01 ` Peter Zijlstra
2020-11-20 12:07 ` Jürgen Groß
2020-11-20 11:46 ` [PATCH v2 07/12] x86: add new features for paravirt patching Juergen Gross
2020-12-08 18:43 ` Borislav Petkov
2020-12-09 7:30 ` Jürgen Groß
2020-12-09 12:03 ` Borislav Petkov
2020-12-09 12:22 ` Jürgen Groß
2020-12-10 17:58 ` Borislav Petkov
2020-11-20 11:46 ` [PATCH v2 08/12] x86/paravirt: remove no longer needed 32-bit pvops cruft Juergen Gross
2020-11-20 12:08 ` Peter Zijlstra
2020-11-20 12:16 ` Jürgen Groß
2020-11-20 16:52 ` Arvind Sankar
2020-11-20 11:46 ` [PATCH v2 09/12] x86/paravirt: switch iret pvops to ALTERNATIVE Juergen Gross
2020-11-20 11:46 ` [PATCH v2 10/12] x86/paravirt: add new macros PVOP_ALT* supporting pvops in ALTERNATIVEs Juergen Gross
2020-11-20 11:46 ` [PATCH v2 11/12] x86/paravirt: switch functions with custom code to ALTERNATIVE Juergen Gross
2020-11-20 15:46 ` kernel test robot
2020-11-25 15:46 ` [x86/paravirt] fd8d46a7a2: kernel-selftests.livepatch.test-callbacks.sh.fail kernel test robot
2020-11-20 11:46 ` [PATCH v2 12/12] x86/paravirt: have only one paravirt patch function Juergen Gross
2020-11-20 14:18 ` kernel test robot
2020-11-20 12:53 ` [PATCH v2 00/12] x86: major paravirt cleanup Peter Zijlstra
2020-11-23 13:43 ` Peter Zijlstra
2020-12-15 11:42 ` Jürgen Groß
2020-12-15 14:18 ` Peter Zijlstra
2020-12-15 14:54 ` Peter Zijlstra
2020-12-15 15:07 ` Jürgen Groß
2020-12-16 0:38 ` Josh Poimboeuf
2020-12-16 8:40 ` Peter Zijlstra
2020-12-16 16:56 ` Josh Poimboeuf
2020-12-16 17:58 ` Peter Zijlstra
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