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Date:   Thu, 29 Nov 2018 12:32:46 -0500
From:   Masayoshi Mizuma <msys.mizuma@gmail.com>
To:     Chao Fan <fanc.fnst@cn.fujitsu.com>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org, bp@alien8.de,
        tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com,
        keescook@chromium.org, bhe@redhat.com, indou.takao@jp.fujitsu.com,
        caoj.fnst@cn.fujitsu.com
Subject: Re: [PATCH v12 0/5] x86/boot/KASLR: Parse ACPI table and limit KASLR
 to choosing immovable memory
Message-ID: <20181129173245.etpt52om2b5qpdeq@gabell>
References: <20181129081631.11139-1-fanc.fnst@cn.fujitsu.com>
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Hi Chao,

Thank you for your continued working.

Could you please build your patches before sending?
Your patches depend on the following kconfig,
so please build them under the config combination.

RANDOMIZE_BASE
MEMORY_HOTREMOVE
EARLY_PARSE_RSDP
KEXEC
EFI

Thanks,
Masa

On Thu, Nov 29, 2018 at 04:16:26PM +0800, Chao Fan wrote:
> ***Background:
> People reported that KASLR may randomly choose some positions
> which are located in movable memory regions. This will break memory
> hotplug feature and make the movable memory chosen by KASLR can't be
> removed.
> 
> ***Solutions:
> Get the information of memory hot-remove, then KASLR will know the
> right regions. Information about memory hot-remove is in ACPI
> tables, which will be parsed after start_kernel(), so that KASLR
> can't get the information.
> 
> Somebody suggest to add a kernel parameter to specify the
> immovable memory so that limit KASLR in these regions. Then I make
> a patchset. After several versions, Ingo gave a suggestion:
> https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1634024.html
> Follow Ingo's suggestion, imitate the ACPI code to parse the ACPI
> tables, so that the kaslr can get necessary memory information in
> ACPI tables.
> I think ACPI code is an independent part, so imitate the codes
> and functions to 'compressed/' directory, so that kaslr won't
> influence the initialization of ACPI.
> 
> PATCH 1/5 Add get_acpi_rsdp() to parse RSDP in cmdline from KEXEC
> PATCH 2/5 Add efi_get_rsdp_addr() to find RSDP from EFI table when
>           booting from EFI.
> PATCH 3/5 Add bios_get_rsdp_addr() to search RSDP in memory when EFI
>           table not found.
> PATCH 4/5 Compute SRAT table from RSDP and walk SRAT table to store
>           the immovable memory regions.
> PATCH 5/5 Calculate the intersection between memory regions from e820/efi
>           memory table and immovable memory regions. Limit KASLR to
>           choosing these regions for randomization.
> 
> v1->v2:
>  -  Simplify some code.
> Follow Baoquan He's suggestion:
>  - Reuse the head file of acpi code.
> 
> v2->v3:
>  - Test in more conditions, so remove the 'RFC' tag.
>  - Change some comments.
> 
> v3->v4:
> Follow Thomas Gleixner's suggetsion:
>  - Put the whole efi related function into #define CONFIG_EFI and return
>    false in the other stub.
> 
> v4->v5:
> Follow Dou Liyang's suggestion:
>  - Add more comments about some functions based on kernel code.
>  - Change some typo in comments.
>  - Clean useless variable.
>  - Add check for the boundary of array.
>  - Add check for 'movable_node' parameter
> 
> v5->v6:
> Follow Baoquan He's suggestion:
>  - Change some log.
>  - Add the check for acpi_rsdp
>  - Change some code logical to make code clear
> 
> v6->v7:
> Follow Rafael's suggestion:
>  - Add more comments and patch log.
> Follow test robot's suggestion:
>  - Add "static" tag for function
> 
> v7-v8:
> Follow Kees Cook's suggestion:
>  - Use mem_overlaps() to check memory region.
>  - Use #ifdef in the definition of function.
> 
> v8-v9:
> Follow Boris' suggestion:
>  - Change code style.
>  - Splite PATCH 1/3 to more path.
>  - Introduce some new function
>  - Use existing function to rework some code
> Follow Masayoshi's suggetion:
>  - Make code more readable
> 
> v9->v10:
> Follow Baoquan's suggestion:
>  - Change some log
>  - Merge last two patch together.
> 
> v10->v11:
> Follow Boris' suggestion:
>  - Link kstrtoull() instead of copying it.
>  - Drop the useless wrapped function.
> 
> v11->v12:
> Follow Boris' suggestion:
>  - Change patch log and code comments.
>  - Add 'CONFIG_EARLY_PARSE_RSDP' to make code easy to read
>  - Put strtoull() to misc.c
> Follow Masa's suggestion:
>  - Remove the detection for 'movable_node'
>  - Change the code logical about cmdline_find_option()
> 
> Any comments will be welcome.
> 
> 
> Chao Fan (5):
>   x86/boot: Add get_acpi_rsdp() to parse RSDP in cmdline from KEXEC
>   x86/boot: Add efi_get_rsdp_addr() to find RSDP from EFI table
>   x86/boot: Add bios_get_rsdp_addr() to search RSDP in memory
>   x86/boot: Parse SRAT table from RSDP and store immovable memory
>   x86/boot/KASLR: Limit KASLR to extracting kernel in immovable memory
> 
>  arch/x86/Kconfig                  |  10 +
>  arch/x86/boot/compressed/Makefile |   2 +
>  arch/x86/boot/compressed/acpitb.c | 322 ++++++++++++++++++++++++++++++
>  arch/x86/boot/compressed/kaslr.c  |  79 ++++++--
>  arch/x86/boot/compressed/misc.c   |   5 +
>  arch/x86/boot/compressed/misc.h   |  24 +++
>  lib/kstrtox.c                     |   5 +
>  7 files changed, 432 insertions(+), 15 deletions(-)
>  create mode 100644 arch/x86/boot/compressed/acpitb.c
> 
> -- 
> 2.19.1
> 
> 
>