linux-kernel - Re: [PATCH] x86/efi: Add EFI_PGT_DUMP support for x86_32, kexec and efi=old

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 for Android: free password hash cracker in your pocket

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

Message-ID: <20170511111828.pu2i3pn6lyiukgaf@pd.tnic>
Date:   Thu, 11 May 2017 13:18:28 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Sai Praneeth Prakhya <sai.praneeth.prakhya@...el.com>
Cc:     linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Ricardo Neri <ricardo.neri@...el.com>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Ravi Shankar <ravi.v.shankar@...el.com>
Subject: Re: [PATCH] x86/efi: Add EFI_PGT_DUMP support for x86_32, kexec and
 efi=old_map

On Wed, May 10, 2017 at 03:49:05PM -0700, Sai Praneeth Prakhya wrote:
> From: Sai Praneeth <sai.praneeth.prakhya@...el.com>
> 
> EFI_PGT_DUMP, as the name suggests dumps efi page tables to dmesg during
> kernel boot. This feature is very useful while debugging page
> faults/null pointer dereferences to efi related addresses. Presently,
> this feature is limited only to x86_64, so let's extend it to other efi
> configurations like kexec kernel, efi=old_map and to x86_32 as well.
> This doesn't effect normal boot path because this config option should
> be used only for debug purposes.
> 
> Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@...el.com>
> Cc: Borislav Petkov <bp@...en8.de>
> Cc: Ricardo Neri <ricardo.neri@...el.com>
> Cc: Matt Fleming <matt@...eblueprint.co.uk>
> Cc: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> Cc: Ravi Shankar <ravi.v.shankar@...el.com>
> ---
>  arch/x86/platform/efi/efi.c    | 2 ++
>  arch/x86/platform/efi/efi_32.c | 9 ++++++++-
>  arch/x86/platform/efi/efi_64.c | 5 ++++-
>  3 files changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
> index 217dc166c649..a6d6cd8fe78a 100644
> --- a/arch/x86/platform/efi/efi.c
> +++ b/arch/x86/platform/efi/efi.c
> @@ -890,6 +890,8 @@ static void __init kexec_enter_virtual_mode(void)
>  	if (efi_enabled(EFI_OLD_MEMMAP) && (__supported_pte_mask & _PAGE_NX))
>  		runtime_code_page_mkexec();
>  
> +	efi_dump_pagetable();

You can call that only once at the end of efi_enter_virtual_mode()
instead of adding it here and leaving it in __efi_enter_virtual_mode().

-- 
Regards/Gruss,
    Boris.

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