From: Thomas Gleixner <tglx@linutronix.de>
To: David Woodhouse <dwmw2@infradead.org>,
Usama Arif <usama.arif@bytedance.com>,
kim.phillips@amd.com, brgerst@gmail.com
Cc: piotrgorski@cachyos.org, oleksandr@natalenko.name,
arjan@linux.intel.com, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, hpa@zytor.com, x86@kernel.org,
pbonzini@redhat.com, paulmck@kernel.org,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
rcu@vger.kernel.org, mimoja@mimoja.de, hewenliang4@huawei.com,
thomas.lendacky@amd.com, seanjc@google.com,
pmenzel@molgen.mpg.de, fam.zheng@bytedance.com,
punit.agrawal@bytedance.com, simon.evans@bytedance.com,
liangma@liangbit.com
Subject: Re: [PATCH v12 06/11] x86/smpboot: Remove initial_stack on 64-bit
Date: Wed, 01 Mar 2023 11:18:24 +0100 [thread overview]
Message-ID: <87y1oglqq7.ffs@tglx> (raw)
In-Reply-To: <64B60F62-3760-43A0-A0FB-C349DA70C013@infradead.org>
On Tue, Feb 28 2023 at 20:43, David Woodhouse wrote:
> On 28 February 2023 20:17:19 GMT, Thomas Gleixner <tglx@linutronix.de> wrote:
>>> + * Make the resuming CPU use the temporary stack at startup
>>> + * by setting current->thread.sp to point to that. The true
>>> + * %rsp will be restored with the rest of the CPU context,
>>> + * by do_suspend_lowlevel().
>>
>>Right, but what restores current->thread.sp? thread.sp is used by
>>unwinders...
>
> Unwinding a thread that is actually *on* the CPU?
No.
> By the time it's taken off, won't ->thread.sp have been written out
> again? I figured it was just a dead variable while the actual %rsp was
> in use?
Yes. It's not used when the thread is on the CPU. And you are right,
it's saved and restored in switch_to(). Can you please add a comment to
that effect?
Thanks,
tglx
next prev parent reply other threads:[~2023-03-01 10:18 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-26 11:07 [PATCH v12 00/11] Parallel CPU bringup for x86_64 Usama Arif
2023-02-26 11:07 ` [PATCH v12 01/11] x86/apic/x2apic: Allow CPU cluster_mask to be populated in parallel Usama Arif
2023-02-26 11:07 ` [PATCH v12 02/11] cpu/hotplug: Move idle_thread_get() to <linux/smpboot.h> Usama Arif
2023-02-26 11:07 ` [PATCH v12 03/11] cpu/hotplug: Add dynamic parallel bringup states before CPUHP_BRINGUP_CPU Usama Arif
2023-02-26 11:07 ` [PATCH v12 04/11] x86/smpboot: Reference count on smpboot_setup_warm_reset_vector() Usama Arif
2023-02-26 11:07 ` [PATCH v12 05/11] x86/smpboot: Split up native_cpu_up into separate phases and document them Usama Arif
2023-02-26 11:07 ` [PATCH v12 06/11] x86/smpboot: Remove initial_stack on 64-bit Usama Arif
2023-02-28 16:13 ` Thomas Gleixner
2023-02-28 16:25 ` David Woodhouse
2023-02-28 20:32 ` Thomas Gleixner
2023-02-28 17:09 ` David Woodhouse
2023-02-28 20:17 ` Thomas Gleixner
2023-02-28 20:43 ` David Woodhouse
2023-03-01 10:18 ` Thomas Gleixner [this message]
2023-03-01 10:42 ` David Woodhouse
2023-02-28 22:22 ` Brian Gerst
2023-02-26 11:07 ` [PATCH v12 07/11] x86/smpboot: Remove early_gdt_descr " Usama Arif
2023-02-28 21:01 ` Thomas Gleixner
2023-02-28 21:02 ` Arjan van de Ven
2023-03-01 20:32 ` Josh Triplett
2023-03-01 22:16 ` Paul E. McKenney
2023-03-01 22:25 ` Josh Triplett
2023-03-02 0:28 ` Paul E. McKenney
2023-03-02 1:05 ` Randy Dunlap
2023-03-02 1:37 ` Paul E. McKenney
2023-02-28 21:57 ` David Woodhouse
2023-02-28 22:41 ` David Woodhouse
2023-02-28 22:48 ` Brian Gerst
2023-02-28 23:42 ` David Woodhouse
2023-03-01 0:02 ` H. Peter Anvin
2023-03-01 7:39 ` David Woodhouse
2023-03-01 0:03 ` Brian Gerst
2023-03-01 10:27 ` Thomas Gleixner
2023-02-28 22:09 ` Brian Gerst
2023-02-26 11:07 ` [PATCH v12 08/11] x86/smpboot: Remove initial_gs Usama Arif
2023-02-26 11:08 ` [PATCH v12 09/11] x86/smpboot: Support parallel startup of secondary CPUs Usama Arif
2023-02-26 11:08 ` [PATCH v12 10/11] x86/smpboot: Send INIT/SIPI/SIPI to secondary CPUs in parallel Usama Arif
2023-02-26 11:08 ` [PATCH v12 11/11] x86/smpboot: Serialize topology updates for secondary bringup Usama Arif
2023-02-26 18:31 ` [PATCH v12 00/11] Parallel CPU bringup for x86_64 Oleksandr Natalenko
2023-02-26 20:59 ` [External] " Usama Arif
2023-02-27 6:13 ` David Woodhouse
2023-02-27 6:25 ` Usama Arif
2023-02-27 6:14 ` Usama Arif
2023-02-27 15:29 ` David Woodhouse
2023-02-27 16:32 ` Usama Arif
2023-02-27 21:39 ` Guilherme G. Piccoli
2023-02-28 9:07 ` David Woodhouse
2023-02-28 10:13 ` Paul Menzel
2023-02-28 12:04 ` Guilherme G. Piccoli
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