linux-kernel - Re: [PATCH v2] x86/boot: Use EFI setup data if provided

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]

Message-ID: <20190325123229.GL12016@zn.tnic>
Date:   Mon, 25 Mar 2019 13:32:29 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Dave Young <dyoung@...hat.com>,
        Junichi Nomura <j-nomura@...jp.nec.com>
Cc:     "fanc.fnst@...fujitsu.com" <fanc.fnst@...fujitsu.com>,
        "bhe@...hat.com" <bhe@...hat.com>,
        "kasong@...hat.com" <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 v2] x86/boot: Use EFI setup data if provided

On Mon, Mar 25, 2019 at 08:23:02PM +0800, Dave Young wrote:
> efi_enter_virtual_mode() can only run once because of efi firmware/spec
> limitation,  and after entered virtual mode, efi firmware just updated

I should remember that - I did it at the time.

> Kexec saved the original physical addresses, and pass them to kexeced
> kernel via x86 setup_data, so  both the early parsing or efi init code
> need to get those physical values from setup_data.

So efi_get_rsdp_addr() needs to be refactored in such a way so that at
least the loop towards the end gets carved out into a separate function
- __efi_get_rsdp_addr() or so - which gets config_tables, nr_tables and
size as arguments and finds the RSDP address in the kexec-ed kernel.

So we'd need something like that:

acpi_physical_address get_rsdp_addr(void)
{
        acpi_physical_address pa;

        pa = get_acpi_rsdp();

        if (!pa)
                pa = boot_params->acpi_rsdp_addr;

        if (!pa)
                pa = efi_get_rsdp_addr();

	if (!pa)
		pa = kexec_get_rdsp_addr();		<--- new function

        if (!pa)
                pa = bios_get_rsdp_addr();

        return pa;
}

which would get config_tables from setup_data and call
__efi_get_rsdp_addr() to dig it out in the kexec'ed kernel.

Junichi, ask if it is still unclear what needs to be done.

Thx.

-- 
Regards/Gruss,
    Boris.

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