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From: "Jürgen Groß" <jgross@suse.com>
To: Miroslav Benes <mbenes@suse.cz>,
	boris.ostrovsky@oracle.com, sstabellini@kernel.org,
	tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
	hpa@zytor.com, jpoimboe@redhat.com
Cc: x86@kernel.org, xen-devel@lists.xenproject.org,
	linux-kernel@vger.kernel.org, live-patching@vger.kernel.org,
	jslaby@suse.cz, andrew.cooper3@citrix.com, jbeulich@suse.com
Subject: Re: [PATCH v3 1/2] x86/xen: Make the boot CPU idle task reliable
Date: Thu, 26 Mar 2020 10:29:40 +0100
Message-ID: <f743b8bd-7552-24a8-e7bc-fa8b3bbcb9d2@suse.com> (raw)
In-Reply-To: <20200326092603.7230-2-mbenes@suse.cz>

On 26.03.20 10:26, Miroslav Benes wrote:
> The unwinder reports the boot CPU idle task's stack on XEN PV as
> unreliable, which affects at least live patching. There are two reasons
> for this. First, the task does not follow the x86 convention that its
> stack starts at the offset right below saved pt_regs. It allows the
> unwinder to easily detect the end of the stack and verify it. Second,
> startup_xen() function does not store the return address before jumping
> to xen_start_kernel() which confuses the unwinder.
> 
> Amend both issues by moving the starting point of initial stack in
> startup_xen() and storing the return address before the jump, which is
> exactly what call instruction does.
> 
> Signed-off-by: Miroslav Benes <mbenes@suse.cz>

Reviewed-by: Juergen Gross <jgross@suse.com>


Juergen

  reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-26  9:26 [PATCH v3 0/2] x86/xen: Make idle tasks reliable Miroslav Benes
2020-03-26  9:26 ` [PATCH v3 1/2] x86/xen: Make the boot CPU idle task reliable Miroslav Benes
2020-03-26  9:29   ` Jürgen Groß [this message]
2020-03-26  9:26 ` [PATCH v3 2/2] x86/xen: Make the secondary CPU idle tasks reliable Miroslav Benes
2020-03-26  9:30   ` Jürgen Groß

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