linux-kernel - Re: [PATCH v8 0/3] x86/boot/KASLR: Parse ACPI table and limit kaslr in immovable memory

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Message-ID: <20181108105129.GA7543@zn.tnic>
Date:   Thu, 8 Nov 2018 11:51:29 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Masayoshi Mizuma <msys.mizuma@...il.com>,
        "H. Peter Anvin" <hpa@...or.com>
Cc:     Baoquan He <bhe@...hat.com>, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Chao Fan <fanc.fnst@...fujitsu.com>,
        linux-kernel@...r.kernel.org, x86@...nel.org,
        linux-efi@...r.kernel.org, linux-acpi@...r.kernel.org,
        mingo@...hat.com, hpa@...or.com, keescook@...omium.org,
        rjw@...ysocki.net, lenb@...nel.org, ard.biesheuvel@...aro.org,
        indou.takao@...fujitsu.com, caoj.fnst@...fujitsu.com
Subject: Re: [PATCH v8 0/3] x86/boot/KASLR: Parse ACPI table and limit kaslr
 in immovable memory

On Tue, Nov 06, 2018 at 05:21:34PM -0500, Masayoshi Mizuma wrote:
> On Tue, Nov 06, 2018 at 09:45:11PM +0100, Borislav Petkov wrote:
> > On Tue, Nov 06, 2018 at 02:36:38PM -0500, Masayoshi Mizuma wrote:
> > > Yes, I think I can see what you are saying. However, I'm not sure how
> > > I use the setup_data in legacy BIOS environment.
> > 
> > What is "legacy BIOS environment" and what does that have to do with
> > setup_data?
> 
> My proposed patch [1] is useful only for EFI environment. The patch
> allocates a setup_date structure by efi_call_early() and store the
> KASLR data into the memory area.
> 
> +static void setup_kaslr(struct boot_params *params)
> +{
> +	struct setup_data *kaslr_data = NULL;
> +	struct setup_data *data;
> +	unsigned long size;
> +	efi_status_t status;
> +
> +	size = sizeof(struct setup_data) + sizeof(unsigned long long);
> +
> +	status = efi_call_early(allocate_pool, EFI_LOADER_DATA,
> +			size, (void **)&kaslr_data);
> 
> I'm not sure how I allocate such memory on no EFI environment.

A global definition which doesn't need allocation?

Maybe hpa would have another, better idea...

-- 
Regards/Gruss,
    Boris.

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