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Will Deacon 7c116db24d efi/libstub/arm64: Retain 2MB kernel Image alignment if !KASLR
Since commit 82046702e2 ("efi/libstub/arm64: Replace 'preferred' offset
with alignment check"), loading a relocatable arm64 kernel at a physical
address which is not 2MB aligned and subsequently booting with EFI will
leave the Image in-place, relying on the kernel to relocate itself early
during boot. In conjunction with commit dd4bc60765 ("arm64: warn on
incorrect placement of the kernel by the bootloader"), which enables
CONFIG_RELOCATABLE by default, this effectively means that entering an
arm64 kernel loaded at an alignment smaller than 2MB with EFI (e.g. using
QEMU) will result in silent relocation at runtime.

Unfortunately, this has a subtle but confusing affect for developers
trying to inspect the PC value during a crash and comparing it to the
symbol addresses in vmlinux using tools such as 'nm' or 'addr2line';
all text addresses will be displaced by a sub-2MB offset, resulting in
the wrong symbol being identified in many cases. Passing "nokaslr" on
the command line or disabling "CONFIG_RANDOMIZE_BASE" does not help,
since the EFI stub only copies the kernel Image to a 2MB boundary if it
is not relocatable.

Adjust the EFI stub for arm64 so that the minimum Image alignment is 2MB
unless KASLR is in use.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: David Brazdil <dbrazdil@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
2020-07-13 14:08:07 +01:00
arch arm64/alternatives: don't patch up internal branches 2020-07-09 14:57:59 +01:00
block Kbuild updates for v5.8 (2nd) 2020-06-13 13:29:16 -07:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto Merge branch 'rwonce/rework' of git://git.kernel.org/pub/scm/linux/kernel/git/will/linux 2020-06-10 14:46:54 -07:00
Documentation arm64: Documentation: Fix broken table in generated HTML 2020-07-08 22:20:41 +01:00
drivers efi/libstub/arm64: Retain 2MB kernel Image alignment if !KASLR 2020-07-13 14:08:07 +01:00
fs for-5.8-part2-tag 2020-06-14 09:47:25 -07:00
include Add additional LSM hooks for SafeSetID 2020-06-14 11:39:31 -07:00
init Kbuild updates for v5.8 (2nd) 2020-06-13 13:29:16 -07:00
ipc mmap locking API: use coccinelle to convert mmap_sem rwsem call sites 2020-06-09 09:39:14 -07:00
kernel Add additional LSM hooks for SafeSetID 2020-06-14 11:39:31 -07:00
lib Kbuild updates for v5.8 (2nd) 2020-06-13 13:29:16 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm Kbuild updates for v5.8 (2nd) 2020-06-13 13:29:16 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-06-13 16:27:13 -07:00
samples binderfs: add gitignore for generated sample program 2020-06-13 13:41:24 -07:00
scripts Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-06-13 16:27:13 -07:00
security Add additional LSM hooks for SafeSetID 2020-06-14 11:39:31 -07:00
sound Kbuild updates for v5.8 (2nd) 2020-06-13 13:29:16 -07:00
tools kselftest: arm64: Remove redundant clean target 2020-06-24 14:25:59 +01:00
usr bpfilter: match bit size of bpfilter_umh to that of the kernel 2020-05-17 18:52:01 +09:00
virt MIPS: 2020-06-12 11:05:52 -07:00
.clang-format block: add bio_for_each_bvec_all() 2020-05-25 11:25:24 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore modpost: generate vmlinux.symvers and reuse it for the second modpost 2020-06-06 23:38:12 +09:00
.mailmap A fair amount of stuff this time around, dominated by yet another massive 2020-06-01 15:45:27 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS mailmap: change email for Ricardo Ribalda 2020-05-25 18:59:59 -06:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Merge branch 'i2c/for-5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2020-06-13 13:12:38 -07:00
Makefile Linux 5.8-rc1 2020-06-14 12:45:04 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.