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Filename Latest commit message Latest commit date
Baoquan He 00e5a2bbcc x86/mm/KASLR: Compute the size of the vmemmap section properly
The size of the vmemmap section is hardcoded to 1 TB to support the
maximum amount of system RAM in 4-level paging mode - 64 TB.

However, 1 TB is not enough for vmemmap in 5-level paging mode. Assuming
the size of struct page is 64 Bytes, to support 4 PB system RAM in 5-level,
64 TB of vmemmap area is needed:

  4 * 1000^5 PB / 4096 bytes page size * 64 bytes per page struct / 1000^4 TB = 62.5 TB.

This hardcoding may cause vmemmap to corrupt the following
cpu_entry_area section, if KASLR puts vmemmap very close to it and the
actual vmemmap size is bigger than 1 TB.

So calculate the actual size of the vmemmap region needed and then align
it up to 1 TB boundary.

In 4-level paging mode it is always 1 TB. In 5-level it's adjusted on
demand. The current code reserves 0.5 PB for vmemmap on 5-level. With
this change, the space can be saved and thus used to increase entropy
for the randomization.

 [ bp: Spell out how the 64 TB needed for vmemmap is computed and massage commit
   message. ]

Fixes: eedb92abb9 ("x86/mm: Make virtual memory layout dynamic for CONFIG_X86_5LEVEL=y")
Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Kirill A. Shutemov <kirill@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: kirill.shutemov@linux.intel.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable <stable@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190523025744.3756-1-bhe@redhat.com
2019-06-07 23:12:13 +02:00
arch x86/mm/KASLR: Compute the size of the vmemmap section properly 2019-06-07 23:12:13 +02:00
block block: print offending values when cloned rq limits are exceeded 2019-05-31 15:12:34 -06:00
certs treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36 2019-05-24 17:27:11 +02:00
crypto treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174 2019-05-30 11:26:41 -07:00
Documentation mm, memcg: consider subtrees in memory.events 2019-06-01 15:51:31 -07:00
drivers Merge branch 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-06-02 11:06:13 -07:00
fs for-linus-20190601 2019-06-02 09:27:44 -07:00
include Merge branch 'akpm' (patches from Andrew) 2019-06-02 08:51:30 -07:00
init treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 167 2019-05-30 11:26:39 -07:00
ipc treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 52 2019-05-24 17:36:42 +02:00
kernel Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-06-02 11:08:12 -07:00
lib SPDX fixes for 5.2-rc3, round 2 2019-06-02 10:22:38 -07:00
LICENSES
mm mm/vmalloc: Avoid rare case of flushing TLB with weird arguments 2019-06-03 11:47:25 +02:00
net SPDX update for 5.2-rc3, round 1 2019-05-31 08:34:32 -07:00
samples treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 206 2019-05-30 11:29:53 -07:00
scripts Merge branch 'akpm' (patches from Andrew) 2019-06-02 08:51:30 -07:00
security Merge branch 'next-fixes-for-5.2-rc' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity 2019-05-31 11:08:44 -07:00
sound treewide: fix typos of SPDX-License-Identifier 2019-06-01 18:29:58 +02:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-06-02 11:08:12 -07:00
usr
virt Fixes for PPC and s390. 2019-06-02 10:19:39 -07:00
.clang-format
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes
.gitignore .gitignore: exclude .get_maintainer.ignore and .gitattributes 2019-05-18 11:49:54 +09:00
.mailmap A reasonably busy cycle for docs, including: 2019-05-08 12:42:50 -07:00
COPYING
CREDITS MAINTAINERS: Farewell Martin Schwidefsky 2019-05-31 10:14:11 +02:00
Kbuild
Kconfig
MAINTAINERS Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2019-06-02 10:18:11 -07:00
Makefile Linux 5.2-rc3 2019-06-02 13:55:33 -07:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.