linux-kernel - Re: [PATCH v6 1/2] x86/kexec: Build identity mapping for EFI systab and ACPI tables

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 15 May 2019 08:58:43 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Junichi Nomura <j-nomura@...jp.nec.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Baoquan He <bhe@...hat.com>,
        "kasong@...hat.com" <kasong@...hat.com>,
        "dyoung@...hat.com" <dyoung@...hat.com>,
        "fanc.fnst@...fujitsu.com" <fanc.fnst@...fujitsu.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>,
        "hpa@...or.com" <hpa@...or.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>
Subject: Re: [PATCH v6 1/2] x86/kexec: Build identity mapping for EFI systab
 and ACPI tables

On Wed, May 15, 2019 at 05:17:19AM +0000, Junichi Nomura wrote:
> Hi Kairui,
> 
> On 5/13/19 5:02 PM, Baoquan He wrote:
> > On 05/13/19 at 09:50am, Borislav Petkov wrote:
> >> On Mon, May 13, 2019 at 03:32:54PM +0800, Baoquan He wrote:
> >> So we're going to try it again this cycle and if there's no fallout, it
> >> will go upstream. If not, it will have to be fixed. The usual thing.
> >>
> >> And I don't care if Kairui's patch fixes this one problem - judging by
> >> the fragility of this whole thing, it should be hammered on one more
> >> cycle on as many boxes as possible to make sure there's no other SNAFUs.
> >>
> >> So go test it on more machines instead. I've pushed it here:
> >>
> >> https://git.kernel.org/pub/scm/linux/kernel/git/bp/bp.git/log/?h=next-merge-window
> > 
> > Pingfan has got a machine to reproduce the kexec breakage issue, and
> > applying these two patches fix it. He planned to paste the test result.
> > I will ask him to try this branch if he has time, or I can get his
> > machine to test.
> > 
> > Junichi, also have a try on Boris's branch in NEC's test environment?
> 
> while the patch set works on most of the machines I'm testing around,
> I found kexec(1) fails to load kernel on a few machines if this patch
> is applied.  Those machines don't have IORES_DESC_ACPI_TABLES region
> and have ACPI tables in IORES_DESC_ACPI_NV_STORAGE region instead.

Why? What kind of machines are those?

Why are the ACPI tables in NV storage?

Looking at crash_setup_memmap_entries(), it already maps that type so I
guess this is needed.

+ Rafael and leaving in the rest for reference.

 
> So I think map_acpi_tables() should try to map both regions.  I tried
> following change in addition and it worked.
> 
> -- 
> Jun'ichi Nomura, NEC Corporation / NEC Solution Innovators, Ltd.
> 
> 
> diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
> index 3c77bdf..3837c4a 100644
> --- a/arch/x86/kernel/machine_kexec_64.c
> +++ b/arch/x86/kernel/machine_kexec_64.c
> @@ -56,12 +56,22 @@ static int mem_region_callback(struct resource *res, void *arg)
>  {
>  	unsigned long flags = IORESOURCE_MEM | IORESOURCE_BUSY;
>  	struct init_pgtable_data data;
> +	int ret;
>  
>  	data.info = info;
>  	data.level4p = level4p;
>  	flags = IORESOURCE_MEM | IORESOURCE_BUSY;
> -	return walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1,
> -				   &data, mem_region_callback);
> +	ret = walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1,
> +				  &data, mem_region_callback);
> +	if (ret && ret != -EINVAL)
> +		return ret;
> +
> +	ret = walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1,
> +				  &data, mem_region_callback);
> +	if (ret && ret != -EINVAL)
> +		return ret;
> +
> +	return 0;
>  }
>  #else
>  static int map_acpi_tables(struct x86_mapping_info *info, pgd_t *level4p) { return 0; }

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.