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Ard Biesheuvel bc7c9d6205 efi/libstub/x86: Force 'hidden' visibility for extern declarations
Commit c3710de506 ("efi/libstub/x86: Drop __efi_early() export and
efi_config struct") introduced a reference from C code in eboot.c to
the startup_32 symbol defined in the .S startup code. This results in
a GOT based reference to startup_32, and since GOT entries carry
absolute addresses, they need to be fixed up before they can be used.

On modern toolchains (binutils 2.26 or later), this reference is
relaxed into a R_386_GOTOFF relocation (or the analogous X86_64 one)
which never uses the absolute address in the entry, and so we get
away with not fixing up the GOT table before calling the EFI entry
point. However, GCC 4.6 combined with a binutils of the era (2.24)
will produce a true GOT indirected reference, resulting in a wrong
value to be returned for the address of startup_32() if the boot
code is not running at the address it was linked at.

Fortunately, we can easily override this behavior, and force GCC to
emit the GOTOFF relocations explicitly, by setting the visibility
pragma 'hidden'.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Matthew Garrett <mjg59@google.com>
Cc: linux-efi@vger.kernel.org
Link: https://lkml.kernel.org/r/20200103113953.9571-3-ardb@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-01-10 18:55:01 +01:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-01-09 10:34:07 -08:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
arch efi/libstub/x86: Force 'hidden' visibility for extern declarations 2020-01-10 18:55:01 +01:00
block block: fix splitting segments on boundary masks 2019-12-30 08:51:18 -07:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto tpmdd fixes for Linux v5.5-rc3 2019-12-18 17:17:36 -08:00
drivers Merge branch 'x86/mm' into efi/core, to pick up dependencies 2020-01-10 18:53:14 +01:00
fs pstore fix for rare error path 2020-01-09 21:42:05 -08:00
include Merge branch 'x86/mm' into efi/core, to pick up dependencies 2020-01-10 18:53:14 +01:00
init Revert "fs: remove ksys_dup()" 2020-01-02 16:15:33 -08:00
ipc treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-01-09 10:34:07 -08:00
lib Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-12-22 17:00:04 -08:00
mm Merge branch 'x86/mm' into efi/core, to pick up dependencies 2020-01-10 18:53:14 +01:00
net tipc: fix wrong connect() return code 2020-01-08 15:57:35 -08:00
samples samples/seccomp: Zero out members based on seccomp_notif_sizes 2020-01-02 13:03:39 -08:00
scripts Kbuild fixes for v5.5 (2nd) 2020-01-03 11:21:25 -08:00
security + Bug fixes 2020-01-04 19:28:30 -08:00
sound sound fixes for 5.5-rc5 2020-01-03 11:10:31 -08:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-01-09 10:34:07 -08:00
usr gen_initramfs_list.sh: fix 'bad variable name' error 2020-01-04 00:00:48 +09:00
virt PPC KVM fix for 5.5 2019-12-22 13:18:15 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
.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: dump missing namespaces into a single modules.nsdeps file 2019-11-11 20:10:01 +09:00
.mailmap Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-12-22 09:54:33 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Linux 5.4-rc4 2019-10-29 04:43:29 -06:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-01-09 10:34:07 -08:00
Makefile Linux 5.5-rc5 2020-01-05 14:23:27 -08:00
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.