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Ard Biesheuvel d6d9145866 arm64/alternatives: use subsections for replacement sequences [ Upstream commit `f7b93d4294` ] When building very large kernels, the logic that emits replacement sequences for alternatives fails when relative branches are present in the code that is emitted into the .altinstr_replacement section and patched in at the original site and fixed up. The reason is that the linker will insert veneers if relative branches go out of range, and due to the relative distance of the .altinstr_replacement from the .text section where its branch targets usually live, veneers may be emitted at the end of the .altinstr_replacement section, with the relative branches in the sequence pointed at the veneers instead of the actual target. The alternatives patching logic will attempt to fix up the branch to point to its original target, which will be the veneer in this case, but given that the patch site is likely to be far away as well, it will be out of range and so patching will fail. There are other cases where these veneers are problematic, e.g., when the target of the branch is in .text while the patch site is in .init.text, in which case putting the replacement sequence inside .text may not help either. So let's use subsections to emit the replacement code as closely as possible to the patch site, to ensure that veneers are only likely to be emitted if they are required at the patch site as well, in which case they will be in range for the replacement sequence both before and after it is transported to the patch site. This will prevent alternative sequences in non-init code from being released from memory after boot, but this is tolerable given that the entire section is only 512 KB on an allyesconfig build (which weighs in at 500+ MB for the entire Image). Also, note that modules today carry the replacement sequences in non-init sections as well, and any of those that target init code will be emitted into init sections after this change. This fixes an early crash when booting an allyesconfig kernel on a system where any of the alternatives sequences containing relative branches are activated at boot (e.g., ARM64_HAS_PAN on TX2) Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: James Morse <james.morse@arm.com> Cc: Andre Przywara <andre.przywara@arm.com> Cc: Dave P Martin <dave.martin@arm.com> Link: https://lore.kernel.org/r/20200630081921.13443-1-ardb@kernel.org Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>		2020-07-22 09:32:01 +02:00
arch	arm64/alternatives: use subsections for replacement sequences	2020-07-22 09:32:01 +02:00
block	block: release bip in a right way in error path	2020-07-16 08:17:23 +02:00
certs	export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR()	2018-08-22 23:21:44 +09:00
crypto	crypto: af_alg - fix use-after-free in af_alg_accept() due to bh_lock_sock()	2020-07-09 09:37:10 +02:00
Documentation	mtd: rawnand: Pass a nand_chip object to nand_release()	2020-06-25 15:33:08 +02:00
drivers	drm/exynos: fix ref count leak in mic_pre_enable	2020-07-22 09:32:01 +02:00
firmware	Fix built-in early-load Intel microcode alignment	2020-01-23 08:21:29 +01:00
fs	btrfs: fix fatal extent_buffer readahead vs releasepage race	2020-07-16 08:17:27 +02:00
include	vlan: consolidate VLAN parsing code and limit max parsing depth	2020-07-22 09:32:00 +02:00
init	x86: Fix early boot crash on gcc-10, third try	2020-05-20 08:18:49 +02:00
ipc	ipc/util.c: sysvipc_find_ipc() incorrectly updates position index	2020-05-20 08:18:40 +02:00
kernel	cgroup: fix cgroup_sk_alloc() for sk_clone_lock()	2020-07-22 09:32:00 +02:00
lib	lib/zlib: remove outdated and incorrect pre-increment optimization	2020-06-25 15:33:02 +02:00
LICENSES	LICENSES: Remove CC-BY-SA-4.0 license text	2018-10-18 11:28:50 +02:00
mm	mm/slub: fix stack overruns with SLUB_STATS	2020-07-09 09:37:09 +02:00
net	sched: consistently handle layer3 header accesses in the presence of VLANs	2020-07-22 09:32:00 +02:00
samples	samples: bpf: Fix build error	2020-06-03 08:19:31 +02:00
scripts	kbuild: improve cc-option to clean up all temporary files	2020-06-30 23:17:15 -04:00
security	apparmor: don't try to replace stale label in ptraceme check	2020-06-30 23:17:03 -04:00
sound	ALSA: usb-audio: add quirk for MacroSilicon MS2109	2020-07-16 08:17:25 +02:00
tools	perf: Make perf able to build with latest libbfd	2020-07-22 09:31:58 +02:00
usr	initramfs: restore default compression behavior	2020-04-13 10:44:59 +02:00
virt	KVM: arm64: Synchronize sysreg state on injecting an AArch32 exception	2020-06-22 09:05:09 +02:00
.clang-format	clang-format: Set IndentWrappedFunctionNames false	2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap	libnvdimm-for-4.19_misc	2018-08-25 18:13:10 -07:00
COPYING
CREDITS	9p: remove Ron Minnich from MAINTAINERS	2018-08-17 16:20:26 -07:00
Kbuild
Kconfig	kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt	2018-08-02 08:06:55 +09:00
MAINTAINERS	MAINTAINERS: Update drm/i915 bug filing URL	2020-02-28 16:38:49 +01:00
Makefile	Linux 4.19.133	2020-07-16 08:17:28 +02:00
README

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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.