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Date:   Fri, 30 Nov 2018 09:15:13 +0800
From:   Chao Fan <fanc.fnst@cn.fujitsu.com>
To:     Masayoshi Mizuma <msys.mizuma@gmail.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: <20181130011513.GA1527@localhost.localdomain>
References: <20181129081631.11139-1-fanc.fnst@cn.fujitsu.com>
 <20181129173245.etpt52om2b5qpdeq@gabell>
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On Thu, Nov 29, 2018 at 12:32:46PM -0500, Masayoshi Mizuma wrote:
>Hi Chao,
>
>Thank you for your continued working.

Thanks for your test.

>
>Could you please build your patches before sending?

Sorry for the mistake, I build it with the whole patches.
I found there are some problems with the method to splite patch.
I will rework on it and build every commit.

Thanks,
Chao Fan

>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
>> 
>> 
>> 
>
>