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: <20181106222133.lb7674yzszivzihd@gabell>
Date:   Tue, 6 Nov 2018 17:21:34 -0500
From:   Masayoshi Mizuma <msys.mizuma@...il.com>
To:     Borislav Petkov <bp@...en8.de>
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 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.
Am I missing something...?

[1] https://lkml.kernel.org/r/20181022154204.kagmdb55jtoez4ca@gabell

Thanks,
Masa