linux-kernel - Re: [PATCH v4] x86/boot: Use efi_setup_data for searching RSDP on kexec-ed kernel

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Message-ID: <DFC5B552-9B44-422B-8EAE-A32C24BB7A88@alien8.de>
Date:   Thu, 11 Apr 2019 11:21:28 +0200
From:   Boris Petkov <bp@...en8.de>
To:     Junichi Nomura <j-nomura@...jp.nec.com>
CC:     Dave Young <dyoung@...hat.com>,
        Chao Fan <fanc.fnst@...fujitsu.com>,
        Baoquan He <bhe@...hat.com>, Kairui Song <kasong@...hat.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4] x86/boot: Use efi_setup_data for searching RSDP on kexec-ed kernel

On April 11, 2019 11:13:03 AM GMT+02:00, Junichi Nomura <j-nomura@...jp.nec.com> wrote:
>On 4/11/19 5:37 PM, Borislav Petkov wrote:
>> On Thu, Apr 11, 2019 at 08:16:45AM +0000, Junichi Nomura wrote:
>>> kexec_get_rsdp_addr() might fail on kexec-booted kernel, e.g. if the
>>> setup_data was invalid. In such a case, falling back to
>efi_get_rsdp_addr()
>>> will hit the problem of accessing invalid table pointer again.
>> 
>> Then you need to do this:
>> 
>> 	if (kexeced kernel) {
>> 		addr = kexec_get_rsdp_addr();
>> 		if (!addr) {
>> 			/* cannot get address */
>> 			return -1;
>> 		}
>> 
>> 		return addr;
>> 	}
>> 
>> and the calling function get_rsdp_addr() must check the return value
>and
>> if it is not 0, return immediately.
>
>Do you mean making get_rsdp_addr() like this?

Does that look like what I've typed above?

-- 
Sent from a small device: formatting sux and brevity is inevitable.