In 22f26f21774f8 awk was added to deduplicate *.mod files. The awk
invocation passes -v RS='( |\n)' to match a space or newline character
as the record separator. Unfortunately, POSIX states[1]
> If RS contains more than one character, the results are unspecified.
Some implementations (such as the One True Awk[2] used by the BSDs) do
not treat RS as a regular expression. When awk does not support regex
RS, build failures such as the following are produced (first error using
allmodconfig):
CC [M] arch/x86/events/intel/uncore.o
CC [M] arch/x86/events/intel/uncore_nhmex.o
CC [M] arch/x86/events/intel/uncore_snb.o
CC [M] arch/x86/events/intel/uncore_snbep.o
CC [M] arch/x86/events/intel/uncore_discovery.o
LD [M] arch/x86/events/intel/intel-uncore.o
ld: cannot find uncore_nhmex.o: No such file or directory
ld: cannot find uncore_snb.o: No such file or directory
ld: cannot find uncore_snbep.o: No such file or directory
ld: cannot find uncore_discovery.o: No such file or directory
make[3]: *** [scripts/Makefile.build:422: arch/x86/events/intel/intel-uncore.o] Error 1
make[2]: *** [scripts/Makefile.build:487: arch/x86/events/intel] Error 2
make[1]: *** [scripts/Makefile.build:487: arch/x86/events] Error 2
make: *** [Makefile:1839: arch/x86] Error 2
To avoid this, use printf(1) to produce a newline between each object
path, instead of the space produced by echo(1), so that the default RS
can be used by awk.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/awk.html
[2]: https://github.com/onetrueawk/awk
Bug: 254441685
Fixes: 22f26f21774f ("kbuild: get rid of duplication in *.mod files")
Signed-off-by: Kevin Locke <kevin@kevinlocke.name>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
(cherry picked from commit 7bf179de5b2dfae54a6839eaf7caba44a888ee2e)
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: I1428c191e239a73016237cd762af3ab3af551def
Changes in 5.15.57
x86/traps: Use pt_regs directly in fixup_bad_iret()
x86/entry: Switch the stack after error_entry() returns
x86/entry: Move PUSH_AND_CLEAR_REGS out of error_entry()
x86/entry: Don't call error_entry() for XENPV
objtool: Classify symbols
objtool: Explicitly avoid self modifying code in .altinstr_replacement
objtool: Shrink struct instruction
objtool,x86: Replace alternatives with .retpoline_sites
objtool: Introduce CFI hash
x86/retpoline: Remove unused replacement symbols
x86/asm: Fix register order
x86/asm: Fixup odd GEN-for-each-reg.h usage
x86/retpoline: Move the retpoline thunk declarations to nospec-branch.h
x86/retpoline: Create a retpoline thunk array
x86/alternative: Implement .retpoline_sites support
x86/alternative: Handle Jcc __x86_indirect_thunk_\reg
x86/alternative: Try inline spectre_v2=retpoline,amd
x86/alternative: Add debug prints to apply_retpolines()
bpf,x86: Simplify computing label offsets
bpf,x86: Respect X86_FEATURE_RETPOLINE*
objtool: Default ignore INT3 for unreachable
x86/entry: Remove skip_r11rcx
x86/realmode: build with -D__DISABLE_EXPORTS
x86/kvm/vmx: Make noinstr clean
x86/cpufeatures: Move RETPOLINE flags to word 11
x86/retpoline: Cleanup some #ifdefery
x86/retpoline: Swizzle retpoline thunk
x86/retpoline: Use -mfunction-return
x86: Undo return-thunk damage
x86,objtool: Create .return_sites
objtool: skip non-text sections when adding return-thunk sites
x86,static_call: Use alternative RET encoding
x86/ftrace: Use alternative RET encoding
x86/bpf: Use alternative RET encoding
x86/kvm: Fix SETcc emulation for return thunks
x86/vsyscall_emu/64: Don't use RET in vsyscall emulation
x86/sev: Avoid using __x86_return_thunk
x86: Use return-thunk in asm code
x86/entry: Avoid very early RET
objtool: Treat .text.__x86.* as noinstr
x86: Add magic AMD return-thunk
x86/bugs: Report AMD retbleed vulnerability
x86/bugs: Add AMD retbleed= boot parameter
x86/bugs: Enable STIBP for JMP2RET
x86/bugs: Keep a per-CPU IA32_SPEC_CTRL value
x86/entry: Add kernel IBRS implementation
x86/bugs: Optimize SPEC_CTRL MSR writes
x86/speculation: Add spectre_v2=ibrs option to support Kernel IBRS
x86/bugs: Split spectre_v2_select_mitigation() and spectre_v2_user_select_mitigation()
x86/bugs: Report Intel retbleed vulnerability
intel_idle: Disable IBRS during long idle
objtool: Update Retpoline validation
x86/xen: Rename SYS* entry points
x86/xen: Add UNTRAIN_RET
x86/bugs: Add retbleed=ibpb
x86/bugs: Do IBPB fallback check only once
objtool: Add entry UNRET validation
x86/cpu/amd: Add Spectral Chicken
x86/speculation: Fix RSB filling with CONFIG_RETPOLINE=n
x86/speculation: Fix firmware entry SPEC_CTRL handling
x86/speculation: Fix SPEC_CTRL write on SMT state change
x86/speculation: Use cached host SPEC_CTRL value for guest entry/exit
x86/speculation: Remove x86_spec_ctrl_mask
objtool: Re-add UNWIND_HINT_{SAVE_RESTORE}
KVM: VMX: Flatten __vmx_vcpu_run()
KVM: VMX: Convert launched argument to flags
KVM: VMX: Prevent guest RSB poisoning attacks with eIBRS
KVM: VMX: Fix IBRS handling after vmexit
x86/speculation: Fill RSB on vmexit for IBRS
x86/common: Stamp out the stepping madness
x86/cpu/amd: Enumerate BTC_NO
x86/retbleed: Add fine grained Kconfig knobs
x86/bugs: Add Cannon lake to RETBleed affected CPU list
x86/entry: Move PUSH_AND_CLEAR_REGS() back into error_entry
x86/bugs: Do not enable IBPB-on-entry when IBPB is not supported
x86/kexec: Disable RET on kexec
x86/speculation: Disable RRSBA behavior
x86/static_call: Serialize __static_call_fixup() properly
x86/xen: Fix initialisation in hypercall_page after rethunk
x86/asm/32: Fix ANNOTATE_UNRET_SAFE use on 32-bit
x86/speculation: Use DECLARE_PER_CPU for x86_spec_ctrl_current
efi/x86: use naked RET on mixed mode call wrapper
x86/kvm: fix FASTOP_SIZE when return thunks are enabled
KVM: emulate: do not adjust size of fastop and setcc subroutines
tools arch x86: Sync the msr-index.h copy with the kernel sources
tools headers cpufeatures: Sync with the kernel sources
x86/bugs: Remove apostrophe typo
um: Add missing apply_returns()
x86: Use -mindirect-branch-cs-prefix for RETPOLINE builds
Linux 5.15.57
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I41605a6dc38163a964d921f2d4ec8a1a316a5cbc
commit f43b9876e857c739d407bc56df288b0ebe1a9164 upstream.
Do fine-grained Kconfig for all the various retbleed parts.
NOTE: if your compiler doesn't support return thunks this will
silently 'upgrade' your mitigation to IBPB, you might not like this.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
[cascardo: there is no CONFIG_OBJTOOL]
[cascardo: objtool calling and option parsing has changed]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 8f0c32c788fffa8e88f995372415864039347c8a ]
Commit b1a1a1a09b ("kbuild: lto: postpone objtool") moved objtool_args
to Makefile.lib, so the arguments can be used in Makefile.modfinal as
well as Makefile.build.
With commit 850ded46c6 ("kbuild: Fix TRIM_UNUSED_KSYMS with
LTO_CLANG"), module LTO linking came back to scripts/Makefile.build
again.
So, there is no more reason to keep objtool_args in a separate file.
Get it back to the original place, close to the objtool command.
Remove the stale comment too.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ld and ar support @file, which command-line options are read from.
Now that *.mod lists the member objects in the correct order, without
duplication, it is ready to be passed to ld and ar.
By using the @file syntax, people will not be worried about the pitfall
described in the NOTE.
Bug: 175420575
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
(cherry picked from commit 9170b27757d21460755254045bad4933cb631776
https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git kbuild)
[eberman: Fix conflicts with commit 557054d]
Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
Change-Id: Id5bbd99ce940dc5eb40e2f9e75182a50a2eeff47
The dependency
$(obj)/%.mod: $(obj)/%$(mod-prelink-ext).o
... exists because *.mod files previously contained undefined symbols,
which are computed from *.o files when CONFIG_TRIM_UNUSED_KSYMS=y.
Now that the undefined symbols are put into separate *.usyms files,
there is no reason to make *.mod depend on *.o files.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Bug: 175420575
(cherry picked from commit 21b526ad634448369bbadc2f112ed2c716805e63
https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git kbuild)
Change-Id: I7f0e7872ccb54467a33c951d0551fe49be9a36fd
Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
It is allowed to add the same objects multiple times to obj-y / obj-m:
obj-y += foo.o foo.o foo.o
obj-m += bar.o bar.o bar.o
It is also allowed to add the same objects multiple times to a composite
module:
obj-m += foo.o
foo-y := foo1.o foo2.o foo2.o foo1.o
This flexibility is useful because the same object might be selected by
different CONFIG options, like this:
obj-m += foo.o
foo-y := foo1.o
foo-$(CONFIG_FOO_X) += foo2.o
foo-$(CONFIG_FOO_Y) += foo2.o
The duplicated objects are omitted at link time. It works naturally in
Makefiles because GNU Make removes duplication in $^ without changing
the order.
It is working well, almost...
A small flaw I notice is, *.mod contains duplication in such a case.
This is probably not a big deal. As far as I know, the only small
problem is scripts/mod/sumversion.c parses the same file multiple
times.
I am fixing this because I plan to reuse *.mod for other purposes,
where the duplication can be problematic.
The code change is quite simple. We already use awk to drop duplicated
lines in modules.order (see cmd_modules_order in the same file).
I copied the code, but changed RS to use spaces as record separators.
I also changed the file format to list one object per line.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Bug: 175420575
(cherry picked from commit 62d88fd6ef3e52c355ec82e1aef530e72cf690e5
https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git kbuild)
Change-Id: Icd83764f7064c7abf4f8bcf9cf784c8c25c52192
Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
The *.mod files have two lines; the first line lists the member objects
of the module, and the second line, if CONFIG_TRIM_UNUSED_KSYMS=y, lists
the undefined symbols.
Currently, we generate *.mod after constructing composite modules,
otherwise, we cannot compute the second line. No prerequisite is
required to print the first line.
They are orthogonal. Splitting them into separate commands will ease
further cleanups.
This commit splits the list of undefined symbols out to *.usyms files.
Previously, the list of undefined symbols ended up with a very long
line, but now it has one symbol per line.
Use sed like we did before commit 7d32358be8 ("kbuild: avoid split
lines in .mod files").
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Bug: 175420575
(cherry picked from commit 2f6b64906adf99b4c5ea9356df793766d290cfb4
https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git kbuild)
Change-Id: Ic801d2bf085aff6e50d15d196c43da4df3aa88c8
Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
Permit the use of AR archives in .a format as input to the partial link
that produces a kernel module. This permits a set of builtin objects to
be bundled with a module object, to create a single module carrying the
payload of several modules. This is used by the FIPS 140 module.
Bug: 153614920
Bug: 188620248
Change-Id: I7183e6922a03aed498f947062bf0d36709371294
Signed-off-by: Ard Biesheuvel <ardb@google.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
This reverts commit a2480b4d7e.
LibELF is now linkable from the Android Kernel build infra thanks to a
recent patch making hermetic the default for all builds.
Bug: 191637574
Fixes: a2480b4d7e ("Revert "kbuild: remove libelf checks from top Makefile"")
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Change-Id: I6eb8aced5766ea759780d27e82b34256971fdf50
Steps on the way to 5.15-rc1
Fixed up merge conflicts in:
scripts/Makefile.modfinal
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I3a916b7267fc2e4ed2f2bd308b9cff8ca9430660
cmd_update_lto_symversions merges all the existing *.symversions, but
some of them might be stale.
If the last EXPORT_SYMBOL is removed from a C file, the *.symversions
file is not deleted or updated. It contains stale CRCs, but still they
will be used for linking the vmlinux or modules.
It is not a big deal when the EXPORT_SYMBOL is really removed. However,
when the EXPORT_SYMBOL is moved to another file, the same __crc_<symbol>
will appear twice in the merged *.symversions, possibly with different
CRCs if the function argument is changed at the same time. It would
confuse module versioning.
If no EXPORT_SYMBOL is found, let's remove *.symversions explicitly.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
This is not used anywhere because the short log is displayed when
it is used through a $(call cmd,...) invocation.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
With CONFIG_LTO_CLANG, we currently link modules into native
code just before modpost, which means with TRIM_UNUSED_KSYMS
enabled, we still look at the LLVM bitcode in the .o files when
generating the list of used symbols. As the bitcode doesn't
yet have calls to compiler intrinsics and llvm-nm doesn't see
function references that only exist in function-level inline
assembly, we currently need a whitelist for TRIM_UNUSED_KSYMS to
work with LTO.
This change moves module LTO linking to happen earlier, and
thus avoids the issue with LLVM bitcode and TRIM_UNUSED_KSYMS
entirely, allowing us to also drop the whitelist from
gen_autoksyms.sh.
Link: https://github.com/ClangBuiltLinux/linux/issues/1369
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Alexander Lobakin <alobakin@pm.me>
Tested-by: Alexander Lobakin <alobakin@pm.me>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
When building modules(CONFIG_...=m), I found some of module versions
are incorrect and set to 0.
This can be found in build log for first clean build which shows
WARNING: EXPORT symbol "XXXX" [drivers/XXX/XXX.ko] version generation failed,
symbol will not be versioned.
But in second build(incremental build), the WARNING disappeared and the
module version becomes valid CRC and make someone who want to change
modules without updating kernel image can't insert their modules.
The problematic code is
+ $(foreach n, $(filter-out FORCE,$^), \
+ $(if $(wildcard $(n).symversions), \
+ ; cat $(n).symversions >> $@.symversions))
For example:
rm -f fs/notify/built-in.a.symversions ; rm -f fs/notify/built-in.a; \
llvm-ar cDPrST fs/notify/built-in.a fs/notify/fsnotify.o \
fs/notify/notification.o fs/notify/group.o ...
`foreach n` shows nothing to `cat` into $(n).symversions because
`if $(wildcard $(n).symversions)` return nothing, but actually
they do exist during this line was executed.
-rw-r--r-- 1 root root 168580 Jun 13 19:10 fs/notify/fsnotify.o
-rw-r--r-- 1 root root 111 Jun 13 19:10 fs/notify/fsnotify.o.symversions
The reason is the $(n).symversions are generated at runtime, but
Makefile wildcard function expends and checks the file exist or not
during parsing the Makefile.
Thus fix this by use `test` shell command to check the file
existence in runtime.
Rebase from both:
1. [https://lore.kernel.org/lkml/20210616080252.32046-1-lecopzer.chen@mediatek.com/]
2. [https://lore.kernel.org/lkml/20210702032943.7865-1-lecopzer.chen@mediatek.com/]
Fixes: 38e8918490 ("kbuild: lto: fix module versioning")
Co-developed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
This reverts commit 0d989ac2c9.
Android kernel isn't ready for this change yet. Here's why:
There are a couple of different methods for linking the Android
kernel presently, hermetically and not. When *not* building
hermetically, the kernel is linked against locally installed
libraries (OpenSSL, LibElf, etc), usually installed by the distro.
Since these are usually fully fledged versions, they're usually
sufficient for any possible combination of build options.
However, when building hermetically (the intended default), the kernel
is linked against libraries contained in the `repo` controlled AOSP
repositories. This is not a problem for the vast majority of the
important builds, but x86 allmodconfig builds require more
functionality than is presently provided.
This revert changes the presence of LibElf to be voluntary again.
Meaning that we do not have to insist on the presence of a locally
installed instance.
Once OpenSSL (currently provided via BoringSSL) is upgraded to a more
featureful offering, we can consider re-inclusion of this patch.
Change-Id: I810139b034e1a6c2db4dc9fa8871279f5edf215d
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Pull Kbuild updates from Masahiro Yamada:
- Increase the -falign-functions alignment for the debug option.
- Remove ugly libelf checks from the top Makefile.
- Make the silent build (-s) more silent.
- Re-compile the kernel if KBUILD_BUILD_TIMESTAMP is specified.
- Various script cleanups
* tag 'kbuild-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (27 commits)
scripts: add generic syscallnr.sh
scripts: check duplicated syscall number in syscall table
sparc: syscalls: use pattern rules to generate syscall headers
parisc: syscalls: use pattern rules to generate syscall headers
nds32: add arch/nds32/boot/.gitignore
kbuild: mkcompile_h: consider timestamp if KBUILD_BUILD_TIMESTAMP is set
kbuild: modpost: Explicitly warn about unprototyped symbols
kbuild: remove trailing slashes from $(KBUILD_EXTMOD)
kconfig.h: explain IS_MODULE(), IS_ENABLED()
kconfig: constify long_opts
scripts/setlocalversion: simplify the short version part
scripts/setlocalversion: factor out 12-chars hash construction
scripts/setlocalversion: add more comments to -dirty flag detection
scripts/setlocalversion: remove workaround for old make-kpkg
scripts/setlocalversion: remove mercurial, svn and git-svn supports
kbuild: clean up ${quiet} checks in shell scripts
kbuild: sink stdout from cmd for silent build
init: use $(call cmd,) for generating include/generated/compile.h
kbuild: merge scripts/mkmakefile to top Makefile
sh: move core-y in arch/sh/Makefile to arch/sh/Kbuild
...
I do not see a good reason why only the libelf development package must
be so carefully checked.
Kbuild generally does not check host tools or libraries.
For example, x86_64 defconfig fails to build with no libssl development
package installed.
scripts/extract-cert.c:21:10: fatal error: openssl/bio.h: No such file or directory
21 | #include <openssl/bio.h>
| ^~~~~~~~~~~~~~~
To solve the build error, you need to install libssl-dev or openssl-devel
package, depending on your distribution.
'apt-file search', 'dnf provides', etc. is your frined to find a proper
package to install.
This commit removes all the libelf checks from the top Makefile.
If libelf is missing, objtool will fail to build in a similar pattern:
.../linux/tools/objtool/include/objtool/elf.h:10:10: fatal error: gelf.h: No such file or directory
10 | #include <gelf.h>
You need to install libelf-dev, libelf-devel, or elfutils-libelf-devel
to proceed.
Another remarkable change is, CONFIG_STACK_VALIDATION (without
CONFIG_UNWINDER_ORC) previously continued to build with a warning,
but now it will treat missing libelf as an error.
This is just a one-time installation, so it should not hurt to break
a build and make a user install the package.
BTW, the traditional way to handle such checks is autotool, but according
to [1], I do not expect the kernel build would have similar scripting
like './configure' does.
[1]: https://lore.kernel.org/lkml/CA+55aFzr2HTZVOuzpHYDwmtRJLsVzE-yqg2DHpHi_9ePsYp5ug@mail.gmail.com/
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
"OBJECT_FILES_NON_STANDARD_vma.o := n" has a dependency bug. When
objtool source is updated, the affected object doesn't get re-analyzed
by objtool.
Peter's new variable-sized jump label feature relies on objtool
rewriting the object file. Otherwise the system can fail to boot. That
effectively upgrades this minor dependency issue to a major bug.
The problem is that variables in prerequisites are expanded early,
during the read-in phase. The '$(objtool_dep)' variable indirectly uses
'$@', which isn't yet available when the target prerequisites are
evaluated.
Use '.SECONDEXPANSION:' which causes '$(objtool_dep)' to be expanded in
a later phase, after the target-specific '$@' variable has been defined.
Fixes: b9ab5ebb14 ("objtool: Add CONFIG_STACK_VALIDATION option")
Fixes: ab3257042c ("jump_label, x86: Allow short NOPs")
Reported-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Rename overlay-y to multi-dtb-y, which is a consistent name with
multi-obj-y. Also, use multi-search to avoid code duplication.
Introduce real-dtb-y, which is a consistent name with real-obj-y,
to contain primitive blobs compiled from *.dts. This is used to
calculate the list of *.dt.yaml files.
Set -@ to base DTB without using $(eval ).
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
I think multi-obj-* is clearer, and more consistent with real-obj-*.
Rename as follows:
multi-used-y -> multi-obj-y
multi-used-m -> multi-obj-m
multi-used -> multi-obj-ym
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
scripts/Kbuild.include is included everywhere, but macros such as
cc-option are needed by build targets only.
For example, when 'make clean' traverses the tree, it does not need
to evaluate $(call cc-option,).
Split cc-option, ld-option, etc. to scripts/Makefile.compiler, which
is only included from the top Makefile and scripts/Makefile.build.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
VPATH is used in Kbuild to make pattern rules search for prerequisites
in both $(objtree) and $(srctree). Some of *.c, *.S files are not real
sources, but generated by tools such as flex, bison, perl.
In contrast, I doubt the benefit of --include-dir=$(abs_srctree) because
it is always clear which Makefiles are real sources, and which are not.
So, my hope is to add $(srctree)/ prefix to all check-in Makefiles,
then remove --include-dir=$(abs_srctree) flag in the future.
I am touching only some Kbuild core parts for now. Treewide fixes will
be needed to achieve this goal.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Pull Kbuild updates from Masahiro Yamada:
- Fix false-positive build warnings for ARCH=ia64 builds
- Optimize dictionary size for module compression with xz
- Check the compiler and linker versions in Kconfig
- Fix misuse of extra-y
- Support DWARF v5 debug info
- Clamp SUBLEVEL to 255 because stable releases 4.4.x and 4.9.x
exceeded the limit
- Add generic syscall{tbl,hdr}.sh for cleanups across arches
- Minor cleanups of genksyms
- Minor cleanups of Kconfig
* tag 'kbuild-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (38 commits)
initramfs: Remove redundant dependency of RD_ZSTD on BLK_DEV_INITRD
kbuild: remove deprecated 'always' and 'hostprogs-y/m'
kbuild: parse C= and M= before changing the working directory
kbuild: reuse this-makefile to define abs_srctree
kconfig: unify rule of config, menuconfig, nconfig, gconfig, xconfig
kconfig: omit --oldaskconfig option for 'make config'
kconfig: fix 'invalid option' for help option
kconfig: remove dead code in conf_askvalue()
kconfig: clean up nested if-conditionals in check_conf()
kconfig: Remove duplicate call to sym_get_string_value()
Makefile: Remove # characters from compiler string
Makefile: reuse CC_VERSION_TEXT
kbuild: check the minimum linker version in Kconfig
kbuild: remove ld-version macro
scripts: add generic syscallhdr.sh
scripts: add generic syscalltbl.sh
arch: syscalls: remove $(srctree)/ prefix from syscall tables
arch: syscalls: add missing FORCE and fix 'targets' to make if_changed work
gen_compile_commands: prune some directories
kbuild: simplify access to the kernel's version
...
These have no more user in the upstream code. The use of them has been
warned for a while for external modules. The migration is finished.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
With LTO, LLVM bitcode won't be compiled into native code until
modpost_link, or modfinal for modules. This change postpones calls
to objtool until after these steps, and moves objtool_args to
Makefile.lib, so the arguments can be reused in Makefile.modfinal.
As we didn't have objects to process earlier, we use --duplicate
when processing vmlinux.o. This change also disables unreachable
instruction warnings with LTO to avoid warnings about the int3
padding between functions.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
With CONFIG_MODVERSIONS, version information is linked into each
compilation unit that exports symbols. With LTO, we cannot use this
method as all C code is compiled into LLVM bitcode instead. This
change collects symbol versions into .symversions files and merges
them in link-vmlinux.sh where they are all linked into vmlinux.o at
the same time.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20201211184633.3213045-4-samitolvanen@google.com
This change adds build system support for Clang's Link Time
Optimization (LTO). With -flto, instead of ELF object files, Clang
produces LLVM bitcode, which is compiled into native code at link
time, allowing the final binary to be optimized globally. For more
details, see:
https://llvm.org/docs/LinkTimeOptimization.html
The Kconfig option CONFIG_LTO_CLANG is implemented as a choice,
which defaults to LTO being disabled. To use LTO, the architecture
must select ARCH_SUPPORTS_LTO_CLANG and support:
- compiling with Clang,
- compiling all assembly code with Clang's integrated assembler,
- and linking with LLD.
While using CONFIG_LTO_CLANG_FULL results in the best runtime
performance, the compilation is not scalable in time or
memory. CONFIG_LTO_CLANG_THIN enables ThinLTO, which allows
parallel optimization and faster incremental builds. ThinLTO is
used by default if the architecture also selects
ARCH_SUPPORTS_LTO_CLANG_THIN:
https://clang.llvm.org/docs/ThinLTO.html
To enable LTO, LLVM tools must be used to handle bitcode files, by
passing LLVM=1 and LLVM_IAS=1 options to make:
$ make LLVM=1 LLVM_IAS=1 defconfig
$ scripts/config -e LTO_CLANG_THIN
$ make LLVM=1 LLVM_IAS=1
To prepare for LTO support with other compilers, common parts are
gated behind the CONFIG_LTO option, and LTO can be disabled for
specific files by filtering out CC_FLAGS_LTO.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20201211184633.3213045-3-samitolvanen@google.com
Move function tracer options to Kconfig to make it easier to add
new methods for generating __mcount_loc, and to make the options
available also when building kernel modules.
Note that FTRACE_MCOUNT_USE_* options are updated on rebuild and
therefore, work even if the .config was generated in a different
environment.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20201211184633.3213045-2-samitolvanen@google.com
"xargs echo" is not a safe way to remove line breaks because the input
may exceed the command line limit and xargs may break it up into
multiple invocations of echo. This should never happen because
scripts/gen_autoksyms.sh expects all undefined symbols are placed in
the second line of .mod files.
One possible way is to replace "xargs echo" with
"sed ':x;N;$!bx;s/\n/ /g'" or something, but I rewrote the code by
using awk because it is more readable.
This issue was reported by Sami Tolvanen; in his Clang LTO patch set,
$(multi-used-m) is no longer an ELF object, but a thin archive that
contains LLVM bitcode files. llvm-nm prints out symbols for each
archive member separately, which results a lot of dupications, in some
places, beyond the system-defined limit.
This problem must be fixed irrespective of LTO, and we must ensure
zero possibility of having this issue.
Link: https://lkml.org/lkml/2020/12/1/1658
Reported-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
This change removes all instances of DISABLE_LTO from
Makefiles, as they are currently unused, and the preferred
method of disabling LTO is to filter out the flags instead.
Note added by Masahiro Yamada:
DISABLE_LTO was added as preparation for GCC LTO, but GCC LTO was
not pulled into the mainline. (https://lkml.org/lkml/2014/4/8/272)
Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
The conditional:
ifneq ($(hostprogs),)
... is evaluated to true if $(hostprogs) does not contain any word but
whitespace characters.
ifneq ($(strip $(hostprogs)),)
... is a safe way to avoid interpreting whitespace as a non-empty value,
but I'd rather want to use the side-effect of $(sort ...) to do the
equivalent.
$(sort ...) is used in scripts/Makefile.host in order to drop duplication
in $(hostprogs). It is also useful to strip excessive spaces.
Move $(sort ...) before evaluating the ifneq.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
The host shared library rules are currently implemented in
scripts/Makefile.host, but actually GCC-plugin is the only user of
them. (The VDSO .so files are built for the target by different
build rules) Hence, they do not need to be treewide available.
Move all the relevant build rules to scripts/gcc-plugins/Makefile.
I also optimized the build steps so *.so is directly built from .c
because every upstream plugin is compiled from a single source file.
I am still keeping the multi-file plugin support, which Kees Cook
mentioned might be needed by out-of-tree plugins.
(https://lkml.org/lkml/2019/1/11/1107)
If the plugin, foo.so, is compiled from two files foo.c and foo2.c,
then you can do like follows:
foo-objs := foo.o foo2.o
Single-file plugins do not need the *-objs notation.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
Currently, the directories of objects are automatically created
only for O= builds.
It should not hurt to cater to this for in-tree builds too.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Since the pre-git time the checker is run first, before the compiler.
But if the source file contains some syntax error, the warnings from
the compiler are more useful than those from sparse (and other
checker most probably too).
So move the 'check' command to run after the compiler.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Make modules.order depend on $(obj-m), and use if_changed to build it.
This will avoid unneeded update of modules.order, which will be useful
to optimize the modpost stage.
Currently, the second pass of modpost is always invoked. By checking the
timestamp of modules.order, we can avoid the unneeded modpost.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
built-in.a contains the built-in object paths from the current and sub
directories.
module.order collects the module paths from the current and sub
directories.
Make their build rules look more symmetrical.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Kbuild supports the infrastructure to build host programs, but there
was no support to build userspace programs for the target architecture
(i.e. the same architecture as the kernel).
Sam Ravnborg worked on this in 2014 (https://lkml.org/lkml/2014/7/13/154),
but it was not merged. One problem at that time was, there was no good way
to know whether $(CC) can link standalone programs. In fact, pre-built
kernel.org toolchains [1] are often used for building the kernel, but they
do not provide libc.
Now, we can handle this cleanly because the compiler capability is
evaluated at the Kconfig time. If $(CC) cannot link standalone programs,
the relevant options are hidden by 'depends on CC_CAN_LINK'.
The implementation just mimics scripts/Makefile.host
The userspace programs are compiled with the same flags as the host
programs. In addition, it uses -m32 or -m64 if it is found in
$(KBUILD_CFLAGS).
This new syntax has two usecases.
- Sample programs
Several userspace programs under samples/ include UAPI headers
installed in usr/include. Most of them were previously built for
the host architecture just to use the 'hostprogs' syntax.
However, 'make headers' always works for the target architecture.
This caused the arch mismatch in cross-compiling. To fix this
distortion, sample code should be built for the target architecture.
- Bpfilter
net/bpfilter/Makefile compiles bpfilter_umh as the user mode helper,
and embeds it into the kernel. Currently, it overrides HOSTCC with
CC to use the 'hostprogs' syntax. This hack should go away.
[1]: https://mirrors.edge.kernel.org/pub/tools/crosstool/
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
