x86/boot: Work around broken busybox 'truncate' tool

The GNU coreutils version of truncate, which is the original, accepts a
% prefix for the -s size argument which means the file in question
should

x86/boot: Work around broken busybox 'truncate' tool

The GNU coreutils version of truncate, which is the original, accepts a
% prefix for the -s size argument which means the file in question
should be padded to a multiple of the given size. This is currently used
to pad the setup block of bzImage to a multiple of 4k before appending
the decompressor.

busybox reimplements truncate but does not support this idiom, and
therefore fails the build since commit

9c54baab4401 ("x86/boot: Drop CRC-32 checksum and the build tool that generates it")

Since very little build code within the kernel depends on the 'truncate'
utility, work around this incompatibility by avoiding truncate altogether,
and relying on dd to perform the padding.

Fixes: 9c54baab4401 ("x86/boot: Drop CRC-32 checksum and the build tool that generates it")
Reported-by: <[email protected]>
Tested-by: Philipp Stanner <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Linus Torvalds <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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x86: drop unnecessary prefix map configuration

The toplevel Makefile already provides -fmacro-prefix-map as part of
KBUILD_CPPFLAGS. In contrast to the KBUILD_CFLAGS and KBUILD_AFLAGS
variables, KBU

x86: drop unnecessary prefix map configuration

The toplevel Makefile already provides -fmacro-prefix-map as part of
KBUILD_CPPFLAGS. In contrast to the KBUILD_CFLAGS and KBUILD_AFLAGS
variables, KBUILD_CPPFLAGS is not redefined in the architecture specific
Makefiles. Therefore the toplevel KBUILD_CPPFLAGS do apply just fine, to
both C and ASM sources.

The custom configuration was necessary when it was added in
commit 9e2276fa6eb3 ("arch/x86/boot: Use prefix map to avoid embedded
paths") but has since become unnecessary in commit a716bd743210
("kbuild: use -fmacro-prefix-map for .S sources").

Drop the now unnecessary custom prefix map configuration.

Signed-off-by: Thomas Weißschuh <[email protected]>
Signed-off-by: Masahiro Yamada <[email protected]>

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x86/boot: Drop CRC-32 checksum and the build tool that generates it

Apart from some sanity checks on the size of setup.bin, the only
remaining task carried out by the arch/x86/boot/tools/build.c bui

x86/boot: Drop CRC-32 checksum and the build tool that generates it

Apart from some sanity checks on the size of setup.bin, the only
remaining task carried out by the arch/x86/boot/tools/build.c build tool
is generating the CRC-32 checksum of the bzImage. This feature was added
in commit

7d6e737c8d2698b6 ("x86: add a crc32 checksum to the kernel image.")

without any motivation (or any commit log text, for that matter). This
checksum is not verified by any known bootloader, and given that

a) the checksum of the entire bzImage is reported by most tools (zlib,
rhash) as 0xffffffff and not 0x0 as documented,

b) the checksum is corrupted when the image is signed for secure boot,
which means that no distro ships x86 images with valid CRCs,

it seems quite unlikely that this checksum is being used, so let's just
drop it, along with the tool that generates it.

Instead, use simple file concatenation and truncation to combine the two
pieces into bzImage, and replace the checks on the size of the setup
block with a couple of ASSERT()s in the linker script.

Signed-off-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ian Campbell <[email protected]>
Cc: Linus Torvalds <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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x86/boot: Add a fallthrough annotation

Add implicit fallthrough checking to the decompressor code and fix this
warning:

arch/x86/boot/printf.c: In function ‘vsprintf’:
arch/x86/boot/printf.c:24

x86/boot: Add a fallthrough annotation

Add implicit fallthrough checking to the decompressor code and fix this
warning:

arch/x86/boot/printf.c: In function ‘vsprintf’:
arch/x86/boot/printf.c:248:10: warning: this statement may fall through [-Wimplicit-fallthrough=]
248 | flags |= SMALL;
| ^
arch/x86/boot/printf.c:249:3: note: here
249 | case 'X':
| ^~~~

This is a patch from three years ago which I found in my trees, thus the
SUSE authorship still.

Signed-off-by: Borislav Petkov <[email protected]>
Signed-off-by: Borislav Petkov (AMD) <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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Makefile: remove redundant tool coverage variables

Now Kbuild provides reasonable defaults for objtool, sanitizers, and
profilers.

Remove redundant variables.

Note:

This commit changes the covera

Makefile: remove redundant tool coverage variables

Now Kbuild provides reasonable defaults for objtool, sanitizers, and
profilers.

Remove redundant variables.

Note:

This commit changes the coverage for some objects:

- include arch/mips/vdso/vdso-image.o into UBSAN, GCOV, KCOV
- include arch/sparc/vdso/vdso-image-*.o into UBSAN
- include arch/sparc/vdso/vma.o into UBSAN
- include arch/x86/entry/vdso/extable.o into KASAN, KCSAN, UBSAN, GCOV, KCOV
- include arch/x86/entry/vdso/vdso-image-*.o into KASAN, KCSAN, UBSAN, GCOV, KCOV
- include arch/x86/entry/vdso/vdso32-setup.o into KASAN, KCSAN, UBSAN, GCOV, KCOV
- include arch/x86/entry/vdso/vma.o into GCOV, KCOV
- include arch/x86/um/vdso/vma.o into KASAN, GCOV, KCOV

I believe these are positive effects because all of them are kernel
space objects.

Signed-off-by: Masahiro Yamada <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Tested-by: Roberto Sassu <[email protected]>

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kbuild: use $(src) instead of $(srctree)/$(src) for source directory

Kbuild conventionally uses $(obj)/ for generated files, and $(src)/ for
checked-in source files. It is merely a convention withou

kbuild: use $(src) instead of $(srctree)/$(src) for source directory

Kbuild conventionally uses $(obj)/ for generated files, and $(src)/ for
checked-in source files. It is merely a convention without any functional
difference. In fact, $(obj) and $(src) are exactly the same, as defined
in scripts/Makefile.build:

src := $(obj)

When the kernel is built in a separate output directory, $(src) does
not accurately reflect the source directory location. While Kbuild
resolves this discrepancy by specifying VPATH=$(srctree) to search for
source files, it does not cover all cases. For example, when adding a
header search path for local headers, -I$(srctree)/$(src) is typically
passed to the compiler.

This introduces inconsistency between upstream and downstream Makefiles
because $(src) is used instead of $(srctree)/$(src) for the latter.

To address this inconsistency, this commit changes the semantics of
$(src) so that it always points to the directory in the source tree.

Going forward, the variables used in Makefiles will have the following
meanings:

$(obj) - directory in the object tree
$(src) - directory in the source tree (changed by this commit)
$(objtree) - the top of the kernel object tree
$(srctree) - the top of the kernel source tree

Consequently, $(srctree)/$(src) in upstream Makefiles need to be replaced
with $(src).

Signed-off-by: Masahiro Yamada <[email protected]>
Reviewed-by: Nicolas Schier <[email protected]>

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x86/boot: Split off PE/COFF .data section

Describe the code and data of the decompressor binary using separate
.text and .data PE/COFF sections, so that we will be able to map them
using restricted

x86/boot: Split off PE/COFF .data section

Describe the code and data of the decompressor binary using separate
.text and .data PE/COFF sections, so that we will be able to map them
using restricted permissions once we increase the section and file
alignment sufficiently. This avoids the need for memory mappings that
are writable and executable at the same time, which is something that
is best avoided for security reasons.

Signed-off-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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x86/boot: Derive file size from _edata symbol

Tweak the linker script so that the value of _edata represents the
decompressor binary's file size rounded up to the appropriate alignment.
This removes

x86/boot: Derive file size from _edata symbol

Tweak the linker script so that the value of _edata represents the
decompressor binary's file size rounded up to the appropriate alignment.
This removes the need to calculate it in the build tool, and will make
it easier to refer to the file size from the header directly in
subsequent changes to the PE header layout.

While adding _edata to the sed regex that parses the compressed
vmlinux's symbol list, tweak the regex a bit for conciseness.

This change has no impact on the resulting bzImage binary when
configured with CONFIG_EFI_STUB=y.

Signed-off-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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x86/boot: Drop references to startup_64

The x86 boot image generation tool assign a default value to startup_64
and subsequently parses the actual value from zoffset.h but it never
actually uses the

x86/boot: Drop references to startup_64

The x86 boot image generation tool assign a default value to startup_64
and subsequently parses the actual value from zoffset.h but it never
actually uses the value anywhere. So remove this code.

This change has no impact on the resulting bzImage binary.

Signed-off-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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x86/cpu: Remove X86_FEATURE_NAMES

While discussing to change the visibility of X86_FEATURE_NAMES (see Link)
in order to remove CONFIG_EMBEDDED, Boris suggested to simply make the
X86_FEATURE_NAMES f

x86/cpu: Remove X86_FEATURE_NAMES

While discussing to change the visibility of X86_FEATURE_NAMES (see Link)
in order to remove CONFIG_EMBEDDED, Boris suggested to simply make the
X86_FEATURE_NAMES functionality unconditional.

As the need for really tiny kernel images has gone away and kernel images
with !X86_FEATURE_NAMES are hardly tested, remove this config and the whole
ifdeffery in the source code.

Suggested-by: Borislav Petkov <[email protected]>
Signed-off-by: Lukas Bulwahn <[email protected]>
Signed-off-by: Borislav Petkov (AMD) <[email protected]>
Link: https://lore.kernel.org/all/[email protected]/
Link: https://lore.kernel.org/r/[email protected]

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kbuild: fix "cat: .version: No such file or directory"

Since commit 2df8220cc511 ("kbuild: build init/built-in.a just once"),
the .version file is not touched at all when KBUILD_BUILD_VERSION is
giv

kbuild: fix "cat: .version: No such file or directory"

Since commit 2df8220cc511 ("kbuild: build init/built-in.a just once"),
the .version file is not touched at all when KBUILD_BUILD_VERSION is
given.

If KBUILD_BUILD_VERSION is specified and the .version file is missing
(for example right after 'make mrproper'), "No such file or director"
is shown. Even if the .version exists, it is irrelevant to the version
of the current build.

$ make -j$(nproc) KBUILD_BUILD_VERSION=100 mrproper defconfig all
[ snip ]
BUILD arch/x86/boot/bzImage
cat: .version: No such file or directory
Kernel: arch/x86/boot/bzImage is ready (#)

Show KBUILD_BUILD_VERSION if it is given.

Fixes: 2df8220cc511 ("kbuild: build init/built-in.a just once")
Signed-off-by: Masahiro Yamada <[email protected]>
Reviewed-by: Nicolas Schier <[email protected]>

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x86: kmsan: disable instrumentation of unsupported code

Instrumenting some files with KMSAN will result in kernel being unable to
link, boot or crashing at runtime for various reasons (e.g. infinit

x86: kmsan: disable instrumentation of unsupported code

Instrumenting some files with KMSAN will result in kernel being unable to
link, boot or crashing at runtime for various reasons (e.g. infinite
recursion caused by instrumentation hooks calling instrumented code
again).

Completely omit KMSAN instrumentation in the following places:
- arch/x86/boot and arch/x86/realmode/rm, as KMSAN doesn't work for i386;
- arch/x86/entry/vdso, which isn't linked with KMSAN runtime;
- three files in arch/x86/kernel - boot problems;
- arch/x86/mm/cpu_entry_area.c - recursion.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Alexander Potapenko <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Eric Biggers <[email protected]>
Cc: Eric Biggers <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Herbert Xu <[email protected]>
Cc: Ilya Leoshkevich <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michael S. Tsirkin <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Vegard Nossum <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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x86: link vdso and boot with -z noexecstack --no-warn-rwx-segments

Users of GNU ld (BFD) from binutils 2.39+ will observe multiple
instances of a new warning when linking kernels in the form:

ld:

x86: link vdso and boot with -z noexecstack --no-warn-rwx-segments

Users of GNU ld (BFD) from binutils 2.39+ will observe multiple
instances of a new warning when linking kernels in the form:

ld: warning: arch/x86/boot/pmjump.o: missing .note.GNU-stack section implies executable stack
ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
ld: warning: arch/x86/boot/compressed/vmlinux has a LOAD segment with RWX permissions

Generally, we would like to avoid the stack being executable. Because
there could be a need for the stack to be executable, assembler sources
have to opt-in to this security feature via explicit creation of the
.note.GNU-stack feature (which compilers create by default) or command
line flag --noexecstack. Or we can simply tell the linker the
production of such sections is irrelevant and to link the stack as
--noexecstack.

LLVM's LLD linker defaults to -z noexecstack, so this flag isn't
strictly necessary when linking with LLD, only BFD, but it doesn't hurt
to be explicit here for all linkers IMO. --no-warn-rwx-segments is
currently BFD specific and only available in the current latest release,
so it's wrapped in an ld-option check.

While the kernel makes extensive usage of ELF sections, it doesn't use
permissions from ELF segments.

Link: https://lore.kernel.org/linux-block/[email protected]/
Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=ba951afb99912da01a6e8434126b8fac7aa75107
Link: https://github.com/llvm/llvm-project/issues/57009
Reported-and-tested-by: Jens Axboe <[email protected]>
Suggested-by: Fangrui Song <[email protected]>
Signed-off-by: Nick Desaulniers <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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x86/build: Move the install rule to arch/x86/Makefile

Currently, the install target in arch/x86/Makefile descends into
arch/x86/boot/Makefile to invoke the shell script, but there is no
good reason

x86/build: Move the install rule to arch/x86/Makefile

Currently, the install target in arch/x86/Makefile descends into
arch/x86/boot/Makefile to invoke the shell script, but there is no
good reason to do so.

arch/x86/Makefile can run the shell script directly.

Signed-off-by: Masahiro Yamada <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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x86/boot: Modernize genimage script; hdimage+EFI support

The image generation scripts in arch/x86/boot are pretty out of date,
except for the isoimage target. Update and clean up the
genimage.sh scr

x86/boot: Modernize genimage script; hdimage+EFI support

The image generation scripts in arch/x86/boot are pretty out of date,
except for the isoimage target. Update and clean up the
genimage.sh script, and make it support an arbitrary number of
initramfs files in the image.

Add a "hdimage" target, which can be booted by either BIOS or
EFI (if the kernel is compiled with the EFI stub.) For EFI to be able
to pass the command line to the kernel, we need the EFI shell, but the
firmware builtin EFI shell, if it even exists, is pretty much always
the last resort boot option, so search for OVMF or EDK2 and explicitly
include a copy of the EFI shell.

To make this all work, use bash features in the script. Furthermore,
this version of the script makes use of some mtools features,
especially mpartition, that might not exist in very old version of
mtools, but given all the other dependencies on this script this
doesn't seem such a big deal.

Finally, put a volume label ("LINUX_BOOT") on all generated images.

Signed-off-by: H. Peter Anvin (Intel) <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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x86/boot/build: Add phony targets in arch/x86/boot/Makefile to PHONY

These targets are correctly added to PHONY in arch/x86/Makefile, but
not in arch/x86/boot/Makefile. Thus, with a file 'install' i

x86/boot/build: Add phony targets in arch/x86/boot/Makefile to PHONY

These targets are correctly added to PHONY in arch/x86/Makefile, but
not in arch/x86/boot/Makefile. Thus, with a file 'install' in the top
directory, 'make install' does nothing:

$ touch install
$ make install
make[1]: 'install' is up to date.

Add them to the PHONY targets in the boot Makefile too.

[ bp: Massage. ]

Signed-off-by: Masahiro Yamada <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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x86/boot/build: Make 'make bzlilo' not depend on vmlinux or $(obj)/bzImage

bzlilo is an installation target because it copies files to
$(INSTALL_PATH)/, then runs 'lilo'. However, arch/x86/Makefile

x86/boot/build: Make 'make bzlilo' not depend on vmlinux or $(obj)/bzImage

bzlilo is an installation target because it copies files to
$(INSTALL_PATH)/, then runs 'lilo'. However, arch/x86/Makefile and
arch/x86/boot/Makefile have it depend on vmlinux and $(obj)/bzImage,
respectively.

'make bzlilo' may update some build artifacts in the source tree.

As commit

19514fc665ff ("arm, kbuild: make "make install" not depend on vmlinux")

explained, this should not happen.

Make 'bzlilo' not depend on any build artifact.

Signed-off-by: Masahiro Yamada <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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x86/boot/build: Add cpustr.h to targets and remove clean-files

Files in $(targets) are always cleaned up. Move the 'targets' assignment
out of the ifdef and remove 'clean-files'.

Signed-off-by: Mas

x86/boot/build: Add cpustr.h to targets and remove clean-files

Files in $(targets) are always cleaned up. Move the 'targets' assignment
out of the ifdef and remove 'clean-files'.

Signed-off-by: Masahiro Yamada <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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x86/*/Makefile: Use -fno-asynchronous-unwind-tables to suppress .eh_frame sections

While discussing a patch to discard .eh_frame from the compressed
vmlinux using the linker script, Fangrui Song poi

x86/*/Makefile: Use -fno-asynchronous-unwind-tables to suppress .eh_frame sections

While discussing a patch to discard .eh_frame from the compressed
vmlinux using the linker script, Fangrui Song pointed out [1] that these
sections shouldn't exist in the first place because arch/x86/Makefile
uses -fno-asynchronous-unwind-tables.

It turns out this is because the Makefiles used to build the compressed
kernel redefine KBUILD_CFLAGS, dropping this flag.

Add the flag to the Makefile for the compressed kernel, as well as the
EFI stub Makefile to fix this.

Also add the flag to boot/Makefile and realmode/rm/Makefile so that the
kernel's boot code (boot/setup.elf) and realmode trampoline
(realmode/rm/realmode.elf) won't be compiled with .eh_frame sections,
since their linker scripts also just discard them.

[1] https://lore.kernel.org/lkml/[email protected]/

Suggested-by: Fangrui Song <[email protected]>
Signed-off-by: Arvind Sankar <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Nathan Chancellor <[email protected]>
Reviewed-by: Nick Desaulniers <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Tested-by: Nathan Chancellor <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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efi/x86: Add true mixed mode entry point into .compat section

Currently, mixed mode is closely tied to the EFI handover protocol
and relies on intimate knowledge of the bootparams structure, setup
h

efi/x86: Add true mixed mode entry point into .compat section

Currently, mixed mode is closely tied to the EFI handover protocol
and relies on intimate knowledge of the bootparams structure, setup
header etc, all of which are rather byzantine and entirely specific
to x86.

Even though no other EFI supported architectures are currently known
that could support something like mixed mode, it still makes sense to
abstract a bit from this, and make it part of a generic Linux on EFI
boot protocol.

To that end, add a .compat section to the mixed mode binary, and populate
it with the PE machine type and entry point address, allowing firmware
implementations to match it to their native machine type, and invoke
non-native binaries using a secondary entry point.

Signed-off-by: Ard Biesheuvel <[email protected]>

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kbuild: rename hostprogs-y/always to hostprogs/always-y

In old days, the "host-progs" syntax was used for specifying host
programs. It was renamed to the current "hostprogs-y" in 2004.

It is typica

kbuild: rename hostprogs-y/always to hostprogs/always-y

In old days, the "host-progs" syntax was used for specifying host
programs. It was renamed to the current "hostprogs-y" in 2004.

It is typically useful in scripts/Makefile because it allows Kbuild to
selectively compile host programs based on the kernel configuration.

This commit renames like follows:

always -> always-y
hostprogs-y -> hostprogs

So, scripts/Makefile will look like this:

always-$(CONFIG_BUILD_BIN2C) += ...
always-$(CONFIG_KALLSYMS) += ...
...
hostprogs := $(always-y) $(always-m)

I think this makes more sense because a host program is always a host
program, irrespective of the kernel configuration. We want to specify
which ones to compile by CONFIG options, so always-y will be handier.

The "always", "hostprogs-y", "hostprogs-m" will be kept for backward
compatibility for a while.

Signed-off-by: Masahiro Yamada <[email protected]>

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x86/boot/compressed: Relax sed symbol type regex for LLVM ld.lld

The final build stage of the x86 kernel captures some symbol
addresses from the decompressor binary and copies them into zoffset.h.
I

x86/boot/compressed: Relax sed symbol type regex for LLVM ld.lld

The final build stage of the x86 kernel captures some symbol
addresses from the decompressor binary and copies them into zoffset.h.
It uses sed with a regular expression that matches the address, symbol
type and symbol name, and mangles the captured addresses and the names
of symbols of interest into #define directives that are added to
zoffset.h

The symbol type is indicated by a single letter, which we match
strictly: only letters in the set 'ABCDGRSTVW' are matched, even
though the actual symbol type is relevant and therefore ignored.

Commit bc7c9d620 ("efi/libstub/x86: Force 'hidden' visibility for
extern declarations") made a change to the way external symbol
references are classified, resulting in 'startup_32' now being
emitted as a hidden symbol. This prevents the use of GOT entries to
refer to this symbol via its absolute address, which recent toolchains
(including Clang based ones) already avoid by default, making this
change a no-op in the majority of cases.

However, as it turns out, the LLVM linker classifies such hidden
symbols as symbols with static linkage in fully linked ELF binaries,
causing tools such as NM to output a lowercase 't' rather than an upper
case 'T' for the type of such symbols. Since our sed expression only
matches upper case letters for the symbol type, the line describing
startup_32 is disregarded, resulting in a build error like the following

arch/x86/boot/header.S:568:18: error: symbol 'ZO_startup_32' can not be
undefined in a subtraction expression
init_size: .long (0x00000000008fd000 - ZO_startup_32 +
(((0x0000000001f6361c + ((0x0000000001f6361c >> 8) + 65536)
- 0x00000000008c32e5) + 4095) & ~4095)) # kernel initialization size

Given that we are only interested in the value of the symbol, let's match
any character in the set 'a-zA-Z' instead.

Signed-off-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Tested-by: Nathan Chancellor <[email protected]>

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x86, kcsan: Enable KCSAN for x86

This patch enables KCSAN for x86, with updates to build rules to not use
KCSAN for several incompatible compilation units.

Signed-off-by: Marco Elver <elver@google.

x86, kcsan: Enable KCSAN for x86

This patch enables KCSAN for x86, with updates to build rules to not use
KCSAN for several incompatible compilation units.

Signed-off-by: Marco Elver <[email protected]>
Acked-by: Paul E. McKenney <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

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x86/boot: Introduce kernel_info

The relationships between the headers are analogous to the various data
sections:

setup_header = .data
boot_params/setup_data = .bss

What is missing from the ab

x86/boot: Introduce kernel_info

The relationships between the headers are analogous to the various data
sections:

setup_header = .data
boot_params/setup_data = .bss

What is missing from the above list? That's right:

kernel_info = .rodata

We have been (ab)using .data for things that could go into .rodata or .bss for
a long time, for lack of alternatives and -- especially early on -- inertia.
Also, the BIOS stub is responsible for creating boot_params, so it isn't
available to a BIOS-based loader (setup_data is, though).

setup_header is permanently limited to 144 bytes due to the reach of the
2-byte jump field, which doubles as a length field for the structure, combined
with the size of the "hole" in struct boot_params that a protected-mode loader
or the BIOS stub has to copy it into. It is currently 119 bytes long, which
leaves us with 25 very precious bytes. This isn't something that can be fixed
without revising the boot protocol entirely, breaking backwards compatibility.

boot_params proper is limited to 4096 bytes, but can be arbitrarily extended
by adding setup_data entries. It cannot be used to communicate properties of
the kernel image, because it is .bss and has no image-provided content.

kernel_info solves this by providing an extensible place for information about
the kernel image. It is readonly, because the kernel cannot rely on a
bootloader copying its contents anywhere, but that is OK; if it becomes
necessary it can still contain data items that an enabled bootloader would be
expected to copy into a setup_data chunk.

Do not bump setup_header version in arch/x86/boot/header.S because it
will be followed by additional changes coming into the Linux/x86 boot
protocol.

Suggested-by: H. Peter Anvin (Intel) <[email protected]>
Signed-off-by: Daniel Kiper <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Konrad Rzeszutek Wilk <[email protected]>
Reviewed-by: Ross Philipson <[email protected]>
Reviewed-by: H. Peter Anvin (Intel) <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: [email protected]
Cc: Boris Ostrovsky <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Ingo Molnar <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: linux-efi <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Thomas Gleixner <[email protected]>
Cc: x86-ml <[email protected]>
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]

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arch/x86/boot: Use prefix map to avoid embedded paths

It was observed that the kernel embeds the absolute build path in the
x86 boot image when the __FILE__ macro is expanded.

> From https://bugzil

arch/x86/boot: Use prefix map to avoid embedded paths

It was observed that the kernel embeds the absolute build path in the
x86 boot image when the __FILE__ macro is expanded.

> From https://bugzilla.yoctoproject.org/show_bug.cgi?id=13458:

If you turn on the buildpaths QA test, or try a reproducible build, you
discover that the kernel image contains build paths.

$ strings bzImage-5.0.19-yocto-standard |grep tmp/
out of pgt_buf in
/data/poky-tmp/reproducible/tmp/work-shared/qemux86-64/kernel-source/arch/x86/boot/compressed/kaslr_64.c!?

But what's this in the top-level Makefile:

$ git grep prefix-map
Makefile:KBUILD_CFLAGS += $(call
cc-option,-fmacro-prefix-map=$(srctree)/=)

So the __FILE__ shouldn't be using the full path. However
arch/x86/boot/compressed/Makefile has this:

KBUILD_CFLAGS := -m$(BITS) -O2

So that clears KBUILD_FLAGS, removing the -fmacro-prefix-map option.

Use -fmacro-prefix-map to have relative paths in the boot image too.

[ bp: Massage commit message and put the KBUILD_CFLAGS addition in
..boot/Makefile after the KBUILD_AFLAGS assignment because gas
doesn't support -fmacro-prefix-map. ]

Signed-off-by: Bruce Ashfield <[email protected]>
Signed-off-by: Ross Burton <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: George Rimar <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: x86-ml <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Link: https://bugzilla.kernel.org/show_bug.cgi?id=204333

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