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From: Roman Kiryanov <rkir@google.com>
To: Borislav Petkov <bp@alien8.de>
Cc: rjw@rjwysocki.net, pavel@ucw.cz,
	Thomas Gleixner <tglx@linutronix.de>,
	mingo@redhat.com, x86@kernel.org, linux-pm@vger.kernel.org,
	Greg KH <gregkh@linuxfoundation.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Alistair Delva <adelva@google.com>,
	Haitao Shan <hshan@google.com>,
	lkml <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] arch: x86: power: cpu: init %gs before __restore_processor_state (clang)
Date: Tue, 15 Sep 2020 11:36:13 -0700	[thread overview]
Message-ID: <CAOGAQeqhKS48Kd8W4y13ATT3m+nJSksF_U1SJ=SBrOZFrDq9Nw@mail.gmail.com> (raw)
In-Reply-To: <20200915182730.GW14436@zn.tnic>

On Tue, Sep 15, 2020 at 11:27 AM Borislav Petkov <bp@alien8.de> wrote:
> > I believe the kernel makes a questionable assumption on how clang
> > uses registers (gs will not be used if stack protection is disabled).
> > Both kernel and clang behaves unfortunate here.
>
> If the kernel is at fault here and this same thing happens with GCC,
> sure, but this is a clang-specific fix.

This is fair. Unfortunately I am not an x86 asm expert. I expect the proper
fix should land into arch/x86/kernel/acpi/wakeup_64.S to init %gs
(maybe some more registers) before "jmp restore_processor_state".

Regards,
Roman.

  reply	other threads:[~2020-09-15 18:36 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-15 17:26 rkir
2020-09-15 17:46 ` Borislav Petkov
2020-09-15 17:57   ` Roman Kiryanov
2020-09-15 18:27     ` Borislav Petkov
2020-09-15 18:36       ` Roman Kiryanov [this message]
2020-09-15 18:52         ` Borislav Petkov
2020-09-15 18:55           ` Roman Kiryanov
2020-09-18 22:25         ` Pavel Machek
2020-09-21 23:28           ` Roman Kiryanov
2020-10-04  9:59             ` Pavel Machek
2020-09-15 18:00   ` Nick Desaulniers
2020-09-15 18:25     ` Borislav Petkov
2020-09-15 19:51       ` Nick Desaulniers
2020-09-15 20:20         ` Borislav Petkov
2020-09-15 21:49           ` Nick Desaulniers
2020-09-16  9:23             ` Borislav Petkov
2020-09-19 16:48             ` Pavel Machek
2020-09-16  8:17         ` peterz
2020-09-15 20:44     ` Arvind Sankar
2020-09-15 22:17 ` Pavel Machek
2020-09-15 22:21   ` Nick Desaulniers
2020-09-18 22:20     ` Pavel Machek
2020-09-15 23:13   ` Roman Kiryanov

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