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Alexander Lobakin 7734a0f31e x86/boot: Robustify calling startup_{32,64}() from the decompressor code 
After commit ce697ccee1 ("kbuild: remove head-y syntax"), I
started digging whether x86 is ready for removing this old cruft.
Removing its objects from the list makes the kernel unbootable.
This applies only to bzImage, vmlinux still works correctly.
The reason is that with no strict object order determined by the
linker arguments, not the linker script, startup_64 can be placed
not right at the beginning of the kernel.
Here's vmlinux.map's beginning before removing:

  ffffffff81000000         vmlinux.o:(.head.text)
  ffffffff81000000                 startup_64
  ffffffff81000070                 secondary_startup_64
  ffffffff81000075                 secondary_startup_64_no_verify
  ffffffff81000160                 verify_cpu

and after:

  ffffffff81000000         vmlinux.o:(.head.text)
  ffffffff81000000                 pvh_start_xen
  ffffffff81000080                 startup_64
  ffffffff810000f0                 secondary_startup_64
  ffffffff810000f5                 secondary_startup_64_no_verify

Not a problem itself, but the self-extractor code has the address of
that function hardcoded the beginning, not looking onto the ELF
header, which always contains the address of startup_{32,64}().

So, instead of doing an "act of blind faith", just take the address
from the ELF header and extract a relative offset to the entry
point. The decompressor function already returns a pointer to the
beginning of the kernel to the Asm code, which then jumps to it,
so add that offset to the return value.
This doesn't change anything for now, but allows to resign from the
"head object list" for x86 and makes sure valid Kbuild or any other
improvements won't break anything here in general.

Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Jiri Slaby <jirislaby@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20230109170403.4117105-2-alexandr.lobakin@intel.com
 		2023-01-09 18:22:21 +01:00
Documentation Devicetree fixes for v6.2: 2023-01-07 10:20:33 -08:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
arch x86/boot: Robustify calling startup_{32,64}() from the decompressor code 2023-01-09 18:22:21 +01:00
block block-2023-01-06 2023-01-06 13:12:42 -08:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto This update includes the following changes: 2022-12-14 12:31:09 -08:00
drivers Devicetree fixes for v6.2: 2023-01-07 10:20:33 -08:00
fs NFS client fixes for Linux 6.2 2023-01-07 10:38:11 -08:00
include NFS client fixes for Linux 6.2 2023-01-07 10:38:11 -08:00
init Kbuild updates for v6.2 2022-12-19 12:33:32 -06:00
io_uring io_uring: fix CQ waiting timeout handling 2023-01-05 08:04:47 -07:00
ipc Non-MM patches for 6.2-rc1. 2022-12-12 17:28:58 -08:00
kernel Including fixes from bpf, wifi, and netfilter. 2023-01-05 12:40:50 -08:00
lib v6.2 first rc pull request 2023-01-07 10:06:47 -08:00
mm memblock: Fix doc for memblock_phys_free 2023-01-04 12:31:22 +02:00
net NFS client fixes for Linux 6.2 2023-01-07 10:38:11 -08:00
rust rust: types: add `Opaque` type 2022-12-04 01:59:16 +01:00
samples Char/Misc driver changes for 6.2-rc1 2022-12-16 03:49:24 -08:00
scripts kbuild: readd -w option when vmlinux.o or Module.symver is missing 2023-01-05 16:53:48 +09:00
security kernel hardening fixes for v6.2-rc1 2022-12-23 12:00:24 -08:00
sound ALSA: hda/hdmi: Static PCM mapping again with AMD HDMI codecs 2022-12-28 14:05:06 +01:00
tools memblock: small fixes in kernel-doc and tests 2023-01-08 02:54:24 -08:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt Merge branch 'kvm-late-6.1-fixes' into HEAD 2022-12-28 07:19:14 -05:00
.clang-format iommufd for 6.2 2022-12-14 09:15:43 -08:00
.cocciconfig
…
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore *.rpm 2022-12-30 17:22:14 +09:00
.mailmap Non-MM patches for 6.2-rc1. 2022-12-12 17:28:58 -08:00
.rustfmt.toml rust: add `.rustfmt.toml` 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: zram: zsmalloc: Add an additional co-maintainer 2022-12-15 16:37:49 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS block-2023-01-06 2023-01-06 13:12:42 -08:00
Makefile Linux 6.2-rc3 2023-01-08 11:49:43 -06:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.