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Simplify gen_btf logic to make it work with llvm-objcopy. The existing
'file format' and 'architecture' parsing logic is brittle and does not
work with llvm-objcopy/llvm-objdump.
'file format' output of llvm-objdump>=11 will match GNU objdump, but
'architecture' (bfdarch) may not.
.BTF in .tmp_vmlinux.btf is non-SHF_ALLOC. Add the SHF_ALLOC flag
because it is part of vmlinux image used for introspection. C code
can reference the section via linker script defined __start_BTF and
__stop_BTF. This fixes a small problem that previous .BTF had the
SHF_WRITE flag (objcopy -I binary -O elf* synthesized .data).
Additionally, `objcopy -I binary` synthesized symbols
_binary__btf_vmlinux_bin_start and _binary__btf_vmlinux_bin_stop (not
used elsewhere) are replaced with more commonplace __start_BTF and
__stop_BTF.
Add 2>/dev/null because GNU objcopy (but not llvm-objcopy) warns
"empty loadable segment detected at vaddr=0xffffffff81000000, is this intentional?"
We use a dd command to change the e_type field in the ELF header from
ET_EXEC to ET_REL so that lld will accept .btf.vmlinux.bin.o. Accepting
ET_EXEC as an input file is an extremely rare GNU ld feature that lld
does not intend to support, because this is error-prone.
The output section description .BTF in include/asm-generic/vmlinux.lds.h
avoids potential subtle orphan section placement issues and suppresses
--orphan-handling=warn warnings.
Fixes: df786c9b9476 ("bpf: Force .BTF section start to zero when dumping from vmlinux")
Fixes: cb0cc635c7a9 ("powerpc: Include .BTF section")
Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Fangrui Song <maskray@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Stanislav Fomichev <sdf@google.com>
Tested-by: Andrii Nakryiko <andriin@fb.com>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Link: https://github.com/ClangBuiltLinux/linux/issues/871
Link: https://lore.kernel.org/bpf/20200318222746.173648-1-maskray@google.com
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When CONFIG_DEBUG_INFO is enabled, the two kallsyms linking steps spend
time collecting and writing the dwarf sections to the temporary output
files. kallsyms does not need this information, and leaving it off
halves their linking time. This is especially noticeable without
CONFIG_DEBUG_INFO_REDUCED. The BTF linking stage, however, does still
need those details.
Refactor the BTF and kallsyms generation stages slightly for more
regularized temporary names. Skip debug during kallsyms links.
Additionally move "info BTF" to the correct place since commit
8959e39272d6 ("kbuild: Parameterize kallsyms generation and correct
reporting"), which added "info LD ..." to vmlinux_link calls.
For a full debug info build with BTF, my link time goes from 1m06s to
0m54s, saving about 12 seconds, or 18%.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/202003031814.4AEA3351@keescook
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Since commit 56d589361572 ("kbuild: do not create orphan built-in.a or
obj-y objects"), scripts/link-vmlinux.sh does nothing when descending
into init/.
Once the version number becomes out of sync between .version and
include/generated/compile.h, it is not self-healing.
[How to reproduce]
$ echo 100 > .version
$ make
You will see the number in the .version is always bigger than that in
compile.h by one. After this, every time you run 'make', the vmlinux is
re-linked even when none of source files is updated.
Fixes: 56d589361572 ("kbuild: do not create orphan built-in.a or obj-y objects")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
- detect missing include guard in UAPI headers
- do not create orphan built-in.a or obj-y objects
- generate modules.builtin more simply, and drop tristate.conf
- simplify built-in initramfs creation
- make linux-headers deb package thinner
- optimize the deb package build script
- misc cleanups
* tag 'kbuild-v5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (34 commits)
builddeb: split libc headers deployment out into a function
builddeb: split kernel headers deployment out into a function
builddeb: remove redundant make for ARCH=um
builddeb: avoid invoking sub-shells where possible
builddeb: remove redundant $objtree/
builddeb: match temporary directory name to the package name
builddeb: remove unneeded files in hdrobjfiles for headers package
kbuild: use -S instead of -E for precise cc-option test in Kconfig
builddeb: allow selection of .deb compressor
kbuild: remove 'Building modules, stage 2.' log
kbuild: remove *.tmp file when filechk fails
kbuild: remove PYTHON2 variable
modpost: assume STT_SPARC_REGISTER is defined
gen_initramfs.sh: remove intermediate cpio_list on errors
initramfs: refactor the initramfs build rules
gen_initramfs.sh: always output cpio even without -o option
initramfs: add default_cpio_list, and delete -d option support
initramfs: generate dependency list and cpio at the same time
initramfs: specify $(src)/gen_initramfs.sh as a prerequisite in Makefile
initramfs: make initramfs compression choice non-optional
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Pull networking updates from David Miller:
1) Add WireGuard
2) Add HE and TWT support to ath11k driver, from John Crispin.
3) Add ESP in TCP encapsulation support, from Sabrina Dubroca.
4) Add variable window congestion control to TIPC, from Jon Maloy.
5) Add BCM84881 PHY driver, from Russell King.
6) Start adding netlink support for ethtool operations, from Michal
Kubecek.
7) Add XDP drop and TX action support to ena driver, from Sameeh
Jubran.
8) Add new ipv4 route notifications so that mlxsw driver does not have
to handle identical routes itself. From Ido Schimmel.
9) Add BPF dynamic program extensions, from Alexei Starovoitov.
10) Support RX and TX timestamping in igc, from Vinicius Costa Gomes.
11) Add support for macsec HW offloading, from Antoine Tenart.
12) Add initial support for MPTCP protocol, from Christoph Paasch,
Matthieu Baerts, Florian Westphal, Peter Krystad, and many others.
13) Add Octeontx2 PF support, from Sunil Goutham, Geetha sowjanya, Linu
Cherian, and others.
* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1469 commits)
net: phy: add default ARCH_BCM_IPROC for MDIO_BCM_IPROC
udp: segment looped gso packets correctly
netem: change mailing list
qed: FW 8.42.2.0 debug features
qed: rt init valid initialization changed
qed: Debug feature: ilt and mdump
qed: FW 8.42.2.0 Add fw overlay feature
qed: FW 8.42.2.0 HSI changes
qed: FW 8.42.2.0 iscsi/fcoe changes
qed: Add abstraction for different hsi values per chip
qed: FW 8.42.2.0 Additional ll2 type
qed: Use dmae to write to widebus registers in fw_funcs
qed: FW 8.42.2.0 Parser offsets modified
qed: FW 8.42.2.0 Queue Manager changes
qed: FW 8.42.2.0 Expose new registers and change windows
qed: FW 8.42.2.0 Internal ram offsets modifications
MAINTAINERS: Add entry for Marvell OcteonTX2 Physical Function driver
Documentation: net: octeontx2: Add RVU HW and drivers overview
octeontx2-pf: ethtool RSS config support
octeontx2-pf: Add basic ethtool support
...
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When trying to compile with CONFIG_DEBUG_INFO_BTF enabled, I got this
error:
% make -s
Failed to generate BTF for vmlinux
Try to disable CONFIG_DEBUG_INFO_BTF
make[3]: *** [vmlinux] Error 1
Compiling again without -s shows the true error (that pahole is
missing), but since this is fatal, we should show the error
unconditionally on stderr as well, not silence it using the `info`
function. With this patch:
% make -s
BTF: .tmp_vmlinux.btf: pahole (pahole) is not available
Failed to generate BTF for vmlinux
Try to disable CONFIG_DEBUG_INFO_BTF
make[3]: *** [vmlinux] Error 1
Signed-off-by: Chris Down <chris@chrisdown.name>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200122000110.GA310073@chrisdown.name
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Commit bc081dd6e9f6 ("kbuild: generate modules.builtin") added
infrastructure to generate modules.builtin, the list of all
builtin modules.
Basically, it works like this:
- Kconfig generates include/config/tristate.conf, the list of
tristate CONFIG options with a value in a capital letter.
- scripts/Makefile.modbuiltin makes Kbuild descend into
directories to collect the information of builtin modules.
I am not a big fan of it because Kbuild ends up with traversing
the source tree twice.
I am not sure how perfectly it should work, but this approach cannot
avoid false positives; even if the relevant CONFIG option is tristate,
some Makefiles forces obj-m to obj-y.
Some examples are:
arch/powerpc/platforms/powermac/Makefile:
obj-$(CONFIG_NVRAM:m=y) += nvram.o
net/ipv6/Makefile:
obj-$(subst m,y,$(CONFIG_IPV6)) += inet6_hashtables.o
net/netlabel/Makefile:
obj-$(subst m,y,$(CONFIG_IPV6)) += netlabel_calipso.o
Nobody has complained about (or noticed) it, so it is probably fine to
have false positives in modules.builtin.
This commit simplifies the implementation. Let's exploit the fact
that every module has MODULE_LICENSE(). (modpost shows a warning if
MODULE_LICENSE is missing. If so, 0-day bot would already have blocked
such a module.)
I added MODULE_FILE to <linux/module.h>. When the code is being compiled
as builtin, it will be filled with the file path of the module, and
collected into modules.builtin.info. Then, scripts/link-vmlinux.sh
extracts the list of builtin modules out of it.
This new approach fixes the false-positives above, but adds another
type of false-positives; non-modular code may have MODULE_LICENSE()
by mistake. This is not a big deal, it is just the code is always
orphan. We can clean it up if we like. You can see cleanup examples by:
$ git log --grep='make.* explicitly non-modular'
To sum up, this commits deletes lots of code, but still produces almost
equivalent results. Please note it does not increase the vmlinux size at
all. As you can see in include/asm-generic/vmlinux.lds.h, the .modinfo
section is discarded in the link stage.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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Now that the orc_unwind and orc_unwind_ip tables are sorted at build time,
remove the boot time sorting pass.
No change in functionality.
[ mingo: Rewrote the changelog and code comments. ]
Signed-off-by: Shile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kbuild@vger.kernel.org
Link: https://lkml.kernel.org/r/20191204004633.88660-8-shile.zhang@linux.alibaba.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Use a more generic name for additional table sorting usecases,
such as the upcoming ORC table sorting feature. This tool is
not tied to exception table sorting anymore.
No functional changes intended.
[ mingo: Rewrote the changelog. ]
Signed-off-by: Shile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: linux-kbuild@vger.kernel.org
Link: https://lkml.kernel.org/r/20191204004633.88660-6-shile.zhang@linux.alibaba.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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While trying to figure out why fentry_fexit selftest doesn't pass for me
(old pahole, broken BTF), I found out that my latest patch can break vmlinux
.BTF generation. objcopy preserves section start when doing --only-section,
so there is a chance (depending on where pahole inserts .BTF section) to
have leading empty zeroes. Let's explicitly force section offset to zero.
Before:
$ objcopy --set-section-flags .BTF=alloc -O binary \
--only-section=.BTF vmlinux .btf.vmlinux.bin
$ xxd .btf.vmlinux.bin | head -n1
00000000: 0000 0000 0000 0000 0000 0000 0000 0000 ................
After:
$ objcopy --change-section-address .BTF=0 \
--set-section-flags .BTF=alloc -O binary \
--only-section=.BTF vmlinux .btf.vmlinux.bin
$ xxd .btf.vmlinux.bin | head -n1
00000000: 9feb 0100 1800 0000 0000 0000 80e1 1c00 ................
^BTF magic
As part of this change, I'm also dropping '2>/dev/null' from objcopy
invocation to be able to catch possible other issues (objcopy doesn't
produce any warnings for me anymore, it did before with --dump-section).
Fixes: da5fb18225b4 ("bpf: Support pre-2.25-binutils objcopy for vmlinux BTF")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Cc: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20191127225759.39923-1-sdf@google.com
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If vmlinux BTF generation fails, but CONFIG_DEBUG_INFO_BTF is set,
.BTF section of vmlinux is empty and kernel will prohibit
BPF loading and return "in-kernel BTF is malformed".
--dump-section argument to binutils' objcopy was added in version 2.25.
When using pre-2.25 binutils, BTF generation silently fails. Convert
to --only-section which is present on pre-2.25 binutils.
Documentation/process/changes.rst states that binutils 2.21+
is supported, not sure those standards apply to BPF subsystem.
v2:
* exit and print an error if gen_btf fails (John Fastabend)
v3:
* resend with Andrii's Acked-by/Tested-by tags
Fixes: 341dfcf8d78ea ("btf: expose BTF info through sysfs")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20191127161410.57327-1-sdf@google.com
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git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
- add modpost warn exported symbols marked as 'static' because 'static'
and EXPORT_SYMBOL is an odd combination
- break the build early if gold linker is used
- optimize the Bison rule to produce .c and .h files by a single
pattern rule
- handle PREEMPT_RT in the module vermagic and UTS_VERSION
- warn CONFIG options leaked to the user-space except existing ones
- make single targets work properly
- rebuild modules when module linker scripts are updated
- split the module final link stage into scripts/Makefile.modfinal
- fix the missed error code in merge_config.sh
- improve the error message displayed on the attempt of the O= build in
unclean source tree
- remove 'clean-dirs' syntax
- disable -Wimplicit-fallthrough warning for Clang
- add CONFIG_CC_OPTIMIZE_FOR_SIZE_O3 for ARC
- remove ARCH_{CPP,A,C}FLAGS variables
- add $(BASH) to run bash scripts
- change *CFLAGS_<basetarget>.o to take the relative path to $(obj)
instead of the basename
- stop suppressing Clang's -Wunused-function warnings when W=1
- fix linux/export.h to avoid genksyms calculating CRC of trimmed
exported symbols
- misc cleanups
* tag 'kbuild-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (63 commits)
genksyms: convert to SPDX License Identifier for lex.l and parse.y
modpost: use __section in the output to *.mod.c
modpost: use MODULE_INFO() for __module_depends
export.h, genksyms: do not make genksyms calculate CRC of trimmed symbols
export.h: remove defined(__KERNEL__), which is no longer needed
kbuild: allow Clang to find unused static inline functions for W=1 build
kbuild: rename KBUILD_ENABLE_EXTRA_GCC_CHECKS to KBUILD_EXTRA_WARN
kbuild: refactor scripts/Makefile.extrawarn
merge_config.sh: ignore unwanted grep errors
kbuild: change *FLAGS_<basetarget>.o to take the path relative to $(obj)
modpost: add NOFAIL to strndup
modpost: add guid_t type definition
kbuild: add $(BASH) to run scripts with bash-extension
kbuild: remove ARCH_{CPP,A,C}FLAGS
kbuild,arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC
kbuild: Do not enable -Wimplicit-fallthrough for clang for now
kbuild: clean up subdir-ymn calculation in Makefile.clean
kbuild: remove unneeded '+' marker from cmd_clean
kbuild: remove clean-dirs syntax
kbuild: check clean srctree even earlier
...
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${@:2} is BASH-specific extension, which makes link-vmlinux.sh rely on
BASH. Use shift and ${@} instead to fix this issue.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: 341dfcf8d78e ("btf: expose BTF info through sysfs")
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Building s390 kernel with CONFIG_DEBUG_INFO_BTF fails, because
CONFIG_OUTPUT_FORMAT is not defined. As a matter of fact, this variable
appears to be x86-only, so other arches might be affected as well.
Fix by obtaining this value from objdump output, just like it's already
done for bin_arch. The exact objdump invocation is "inspired" by
arch/powerpc/boot/wrapper.
Also, use LANG=C for the existing bin_arch objdump invocation to avoid
potential build issues on systems with non-English locale.
Fixes: 341dfcf8d78e ("btf: expose BTF info through sysfs")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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When kallsyms generation happens, temporary vmlinux outputs are linked
but the quiet make output didn't report it, giving the impression that
the prior command is taking longer than expected.
Instead, report the linking step explicitly. While at it, this
consolidates the repeated "kallsyms generation step" into a single
function and removes the existing copy/pasting.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Daniel Borkmann says:
====================
The following pull-request contains BPF updates for your *net-next* tree.
There is a small merge conflict in libbpf (Cc Andrii so he's in the loop
as well):
for (i = 1; i <= btf__get_nr_types(btf); i++) {
t = (struct btf_type *)btf__type_by_id(btf, i);
if (!has_datasec && btf_is_var(t)) {
/* replace VAR with INT */
t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
<<<<<<< HEAD
/*
* using size = 1 is the safest choice, 4 will be too
* big and cause kernel BTF validation failure if
* original variable took less than 4 bytes
*/
t->size = 1;
*(int *)(t+1) = BTF_INT_ENC(0, 0, 8);
} else if (!has_datasec && kind == BTF_KIND_DATASEC) {
=======
t->size = sizeof(int);
*(int *)(t + 1) = BTF_INT_ENC(0, 0, 32);
} else if (!has_datasec && btf_is_datasec(t)) {
>>>>>>> 72ef80b5ee131e96172f19e74b4f98fa3404efe8
/* replace DATASEC with STRUCT */
Conflict is between the two commits 1d4126c4e119 ("libbpf: sanitize VAR to
conservative 1-byte INT") and b03bc6853c0e ("libbpf: convert libbpf code to
use new btf helpers"), so we need to pick the sanitation fixup as well as
use the new btf_is_datasec() helper and the whitespace cleanup. Looks like
the following:
[...]
if (!has_datasec && btf_is_var(t)) {
/* replace VAR with INT */
t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
/*
* using size = 1 is the safest choice, 4 will be too
* big and cause kernel BTF validation failure if
* original variable took less than 4 bytes
*/
t->size = 1;
*(int *)(t + 1) = BTF_INT_ENC(0, 0, 8);
} else if (!has_datasec && btf_is_datasec(t)) {
/* replace DATASEC with STRUCT */
[...]
The main changes are:
1) Addition of core parts of compile once - run everywhere (co-re) effort,
that is, relocation of fields offsets in libbpf as well as exposure of
kernel's own BTF via sysfs and loading through libbpf, from Andrii.
More info on co-re: http://vger.kernel.org/bpfconf2019.html#session-2
and http://vger.kernel.org/lpc-bpf2018.html#session-2
2) Enable passing input flags to the BPF flow dissector to customize parsing
and allowing it to stop early similar to the C based one, from Stanislav.
3) Add a BPF helper function that allows generating SYN cookies from XDP and
tc BPF, from Petar.
4) Add devmap hash-based map type for more flexibility in device lookup for
redirects, from Toke.
5) Improvements to XDP forwarding sample code now utilizing recently enabled
devmap lookups, from Jesper.
6) Add support for reporting the effective cgroup progs in bpftool, from Jakub
and Takshak.
7) Fix reading kernel config from bpftool via /proc/config.gz, from Peter.
8) Fix AF_XDP umem pages mapping for 32 bit architectures, from Ivan.
9) Follow-up to add two more BPF loop tests for the selftest suite, from Alexei.
10) Add perf event output helper also for other skb-based program types, from Allan.
11) Fix a co-re related compilation error in selftests, from Yonghong.
====================
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
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Expose kernel's BTF under the name vmlinux to be more uniform with using
kernel module names as file names in the future.
Fixes: 341dfcf8d78e ("btf: expose BTF info through sysfs")
Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Make .BTF section allocated and expose its contents through sysfs.
/sys/kernel/btf directory is created to contain all the BTFs present
inside kernel. Currently there is only kernel's main BTF, represented as
/sys/kernel/btf/kernel file. Once kernel modules' BTFs are supported,
each module will expose its BTF as /sys/kernel/btf/<module-name> file.
Current approach relies on a few pieces coming together:
1. pahole is used to take almost final vmlinux image (modulo .BTF and
kallsyms) and generate .BTF section by converting DWARF info into
BTF. This section is not allocated and not mapped to any segment,
though, so is not yet accessible from inside kernel at runtime.
2. objcopy dumps .BTF contents into binary file and subsequently
convert binary file into linkable object file with automatically
generated symbols _binary__btf_kernel_bin_start and
_binary__btf_kernel_bin_end, pointing to start and end, respectively,
of BTF raw data.
3. final vmlinux image is generated by linking this object file (and
kallsyms, if necessary). sysfs_btf.c then creates
/sys/kernel/btf/kernel file and exposes embedded BTF contents through
it. This allows, e.g., libbpf and bpftool access BTF info at
well-known location, without resorting to searching for vmlinux image
on disk (location of which is not standardized and vmlinux image
might not be even available in some scenarios, e.g., inside qemu
during testing).
Alternative approach using .incbin assembler directive to embed BTF
contents directly was attempted but didn't work, because sysfs_proc.o is
not re-compiled during link-vmlinux.sh stage. This is required, though,
to update embedded BTF data (initially empty data is embedded, then
pahole generates BTF info and we need to regenerate sysfs_btf.o with
updated contents, but it's too late at that point).
If BTF couldn't be generated due to missing or too old pahole,
sysfs_btf.c handles that gracefully by detecting that
_binary__btf_kernel_bin_start (weak symbol) is 0 and not creating
/sys/kernel/btf at all.
v2->v3:
- added Documentation/ABI/testing/sysfs-kernel-btf (Greg K-H);
- created proper kobject (btf_kobj) for btf directory (Greg K-H);
- undo v2 change of reusing vmlinux, as it causes extra kallsyms pass
due to initially missing __binary__btf_kernel_bin_{start/end} symbols;
v1->v2:
- allow kallsyms stage to re-use vmlinux generated by gen_btf();
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
|
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Since commit ff9b45c55b26 ("kbuild: modpost: read modules.order instead
of $(MODVERDIR)/*.mod"), 'make vmlinux' emits a warning, like this:
$ make defconfig vmlinux
[ snip ]
LD vmlinux.o
cat: modules.order: No such file or directory
MODPOST vmlinux.o
MODINFO modules.builtin.modinfo
KSYM .tmp_kallsyms1.o
KSYM .tmp_kallsyms2.o
LD vmlinux
SORTEX vmlinux
SYSMAP System.map
When building only vmlinux, KBUILD_MODULES is not set. Hence, the
modules.order is not generated. For the vmlinux modpost, it is not
necessary at all.
Separate scripts/Makefile.modpost for the vmlinux/modules stages.
This works more efficiently because the vmlinux modpost does not
need to include .*.cmd files.
Fixes: ff9b45c55b26 ("kbuild: modpost: read modules.order instead of $(MODVERDIR)/*.mod")
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
- allow users to invoke 'make' out of the source tree
- refactor scripts/mkmakefile
- deprecate KBUILD_SRC, which was used to track the source tree
location for O= build.
- fix recordmcount.pl in case objdump output is localized
- turn unresolved symbols in external modules to errors from warnings
by default; pass KBUILD_MODPOST_WARN=1 to get them back to warnings
- generate modules.builtin.modinfo to collect .modinfo data from
built-in modules
- misc Makefile cleanups
* tag 'kbuild-v5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (21 commits)
.gitignore: add more all*.config patterns
moduleparam: Save information about built-in modules in separate file
Remove MODULE_ALIAS() calls that take undefined macro
.gitignore: add leading and trailing slashes to generated directories
scripts/tags.sh: fix direct execution of scripts/tags.sh
scripts: override locale from environment when running recordmcount.pl
samples: kobject: allow CONFIG_SAMPLE_KOBJECT to become y
samples: seccomp: turn CONFIG_SAMPLE_SECCOMP into a bool option
kbuild: move Documentation to vmlinux-alldirs
kbuild: move samples/ to KBUILD_VMLINUX_OBJS
modpost: make KBUILD_MODPOST_WARN also configurable for external modules
kbuild: check arch/$(SRCARCH)/include/generated before out-of-tree build
kbuild: remove unneeded dependency for include/config/kernel.release
memory: squash drivers/memory/Makefile.asm-offsets
kbuild: use $(srctree) instead of KBUILD_SRC to check out-of-tree build
kbuild: mkmakefile: generate a simple wrapper of top Makefile
kbuild: mkmakefile: do not check the generated Makefile marker
kbuild: allow Kbuild to start from any directory
kbuild: pass $(MAKECMDGOALS) to sub-make as is
kbuild: fix warning "overriding recipe for target 'Makefile'"
...
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Problem:
When a kernel module is compiled as a separate module, some important
information about the kernel module is available via .modinfo section of
the module. In contrast, when the kernel module is compiled into the
kernel, that information is not available.
Information about built-in modules is necessary in the following cases:
1. When it is necessary to find out what additional parameters can be
passed to the kernel at boot time.
2. When you need to know which module names and their aliases are in
the kernel. This is very useful for creating an initrd image.
Proposal:
The proposed patch does not remove .modinfo section with module
information from the vmlinux at the build time and saves it into a
separate file after kernel linking. So, the kernel does not increase in
size and no additional information remains in it. Information is stored
in the same format as in the separate modules (null-terminated string
array). Because the .modinfo section is already exported with a separate
modules, we are not creating a new API.
It can be easily read in the userspace:
$ tr '\0' '\n' < modules.builtin.modinfo
ext4.softdep=pre: crc32c
ext4.license=GPL
ext4.description=Fourth Extended Filesystem
ext4.author=Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others
ext4.alias=fs-ext4
ext4.alias=ext3
ext4.alias=fs-ext3
ext4.alias=ext2
ext4.alias=fs-ext2
md_mod.alias=block-major-9-*
md_mod.alias=md
md_mod.description=MD RAID framework
md_mod.license=GPL
md_mod.parmtype=create_on_open:bool
md_mod.parmtype=start_dirty_degraded:int
...
Co-Developed-by: Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
Signed-off-by: Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com>
Acked-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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When BTF generation is enabled through CONFIG_DEBUG_INFO_BTF,
scripts/link-vmlinux.sh detects if pahole version is too old and
gracefully continues build process, skipping BTF generation build step.
But if pahole is not available, build will still fail. This patch adds
check for whether pahole exists at all and bails out gracefully, if not.
Cc: Alexei Starovoitov <ast@fb.com>
Reported-by: Yonghong Song <yhs@fb.com>
Fixes: e83b9f55448a ("kbuild: add ability to generate BTF type info for vmlinux")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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When CONFIG_DEBUG_INFO_BTF is enabled but available version of pahole is too
old to support BTF generation, build script is supposed to emit warning and
proceed with the build. Due to using exit instead of return from BASH function,
existing handling code prematurely exits exit code 0, not completing some of
the build steps. This patch fixes issue by correctly returning just from
gen_btf() function only.
Fixes: e83b9f55448a ("kbuild: add ability to generate BTF type info for vmlinux")
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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This patch adds new config option to trigger generation of BTF type
information from DWARF debuginfo for vmlinux and kernel modules through
pahole, which in turn relies on libbpf for btf_dedup() algorithm.
The intent is to record compact type information of all types used
inside kernel, including all the structs/unions/typedefs/etc. This
enables BPF's compile-once-run-everywhere ([0]) approach, in which
tracing programs that are inspecting kernel's internal data (e.g.,
struct task_struct) can be compiled on a system running some kernel
version, but would be possible to run on other kernel versions (and
configurations) without recompilation, even if the layout of structs
changed and/or some of the fields were added, removed, or renamed.
This is only possible if BPF loader can get kernel type info to adjust
all the offsets correctly. This patch is a first time in this direction,
making sure that BTF type info is part of Linux kernel image in
non-loadable ELF section.
BTF deduplication ([1]) algorithm typically provides 100x savings
compared to DWARF data, so resulting .BTF section is not big as is
typically about 2MB in size.
[0] http://vger.kernel.org/lpc-bpf2018.html#session-2
[1] https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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As commit 423a8155facf ("kbuild: Fix reading of .config in
link-vmlinux.sh") addressed, some shells fail to perform '.' if
${KCONFIG_CONFIG} does not contain a slash at all.
Instead, we can source include/config/auto.conf, which obviously
contain slashes, and we do not expect its file path overridden by
a user. Perhaps, the performance might be slightly better since
unset CONFIG options are stripped from include/config/auto.conf.
scripts/setlocalversion already works this way.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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The top Makefile does not need to export KBUILD_VMLINUX_INIT and
KBUILD_VMLINUX_MAIN separately.
Put every built-in.a into KBUILD_VMLINUX_OBJS. The order of
$(head-y), $(init-y), $(core-y), ... is still retained.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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The symbol table in the final archive is unneeded; the linker does not
require the symbol table after the --whole-archive option. Every object
file in the archive is included in the link anyway.
Pass thin archives from subdirectories directly to the linker, and
remove the final archiving step.
Fix up the document and comments as well.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Nicholas Piggin <npiggin@gmail.com>
|
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Commit a0f97e06a43c ("kbuild: enable 'make CFLAGS=...' to add
additional options to CC") renamed CFLAGS to KBUILD_CFLAGS.
Commit 222d394d30e7 ("kbuild: enable 'make AFLAGS=...' to add
additional options to AS") renamed AFLAGS to KBUILD_AFLAGS.
Commit 06c5040cdb13 ("kbuild: enable 'make CPPFLAGS=...' to add
additional options to CPP") renamed CPPFLAGS to KBUILD_CPPFLAGS.
For some reason, LDFLAGS was not renamed.
Using a well-known variable like LDFLAGS may result in accidental
override of the variable.
Kbuild generally uses KBUILD_ prefixed variables for the internally
appended options, so here is one more conversion to sanitize the
naming convention.
I did not touch Makefiles under tools/ since the tools build system
is a different world.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
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CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX was selected by BLACKFIN, METAG.
They were removed by commit 4ba66a976072 ("arch: remove blackfin port"),
commit bb6fb6dfcc17 ("metag: Remove arch/metag/"), respectively.
No more architecture enables CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX,
hence the --symbol-prefix option is unnecessary.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
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stat(1) is not standardized and different implementations have their own
(conflicting) flags for querying the size of a file.
ls(1) provides the same information (value of st.st_size) in the 5th
column, except when the file is a character or block device. This output
is standardized[0]. The -n option turns on -l, which writes lines
formatted like
"%s %u %s %s %u %s %s\n", <file mode>, <number of links>,
<owner name>, <group name>, <size>, <date and time>,
<pathname>
but instead of writing the <owner name> and <group name>, it writes the
numeric owner and group IDs (this avoids /etc/passwd and /etc/group
lookups as well as potential field splitting issues).
The <size> field is specified as "the value that would be returned for
the file in the st_size field of struct stat".
To avoid duplicating logic in several locations in the tree, create
scripts/file-size.sh and update callers to use that instead of stat(1).
[0] http://pubs.opengroup.org/onlinepubs/9699919799/utilities/ls.html#tag_20_73_10
Signed-off-by: Michael Forney <forney@google.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Incremental linking is gone, so rename built-in.o to built-in.a, which
is the usual extension for archive files.
This patch does two things, first is a simple search/replace:
git grep -l 'built-in\.o' | xargs sed -i 's/built-in\.o/built-in\.a/g'
The second is to invert nesting of nested text manipulations to avoid
filtering built-in.a out from libs-y2:
-libs-y2 := $(filter-out %.a, $(patsubst %/, %/built-in.a, $(libs-y)))
+libs-y2 := $(patsubst %/, %/built-in.a, $(filter-out %.a, $(libs-y)))
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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This removes the old `ld -r` incremental link option, which has not
been selected by any architecture since June 2017.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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GCC_PLUGINS_CFLAGS is already in the environment, so it is superfluous
to add it in commandline of final build of init/.
Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
"One of the most remarkable improvements in this cycle is, Kbuild is
now able to cache the result of shell commands. Some variables are
expensive to compute, for example, $(call cc-option,...) invokes the
compiler. It is not efficient to redo this computation every time,
even when we are not actually building anything. Kbuild creates a
hidden file ".cache.mk" that contains invoked shell commands and their
results. The speed-up should be noticeable.
Summary:
- Fix arch build issues (hexagon, sh)
- Clean up various Makefiles and scripts
- Fix wrong usage of {CFLAGS,LDFLAGS}_MODULE in arch Makefiles
- Cache variables that are expensive to compute
- Improve cc-ldopton and ld-option for Clang
- Optimize output directory creation"
* tag 'kbuild-v4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (30 commits)
kbuild: move coccicheck help from scripts/Makefile.help to top Makefile
sh: decompressor: add shipped files to .gitignore
frv: .gitignore: ignore vmlinux.lds
selinux: remove unnecessary assignment to subdir-
kbuild: specify FORCE in Makefile.headersinst as .PHONY target
kbuild: remove redundant mkdir from ./Kbuild
kbuild: optimize object directory creation for incremental build
kbuild: create object directories simpler and faster
kbuild: filter-out PHONY targets from "targets"
kbuild: remove redundant $(wildcard ...) for cmd_files calculation
kbuild: create directory for make cache only when necessary
sh: select KBUILD_DEFCONFIG depending on ARCH
kbuild: fix linker feature test macros when cross compiling with Clang
kbuild: shrink .cache.mk when it exceeds 1000 lines
kbuild: do not call cc-option before KBUILD_CFLAGS initialization
kbuild: Cache a few more calls to the compiler
kbuild: Add a cache for generated variables
kbuild: add forward declaration of default target to Makefile.asm-generic
kbuild: remove KBUILD_SUBDIR_ASFLAGS and KBUILD_SUBDIR_CCFLAGS
hexagon/kbuild: replace CFLAGS_MODULE with KBUILD_CFLAGS_MODULE
...
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Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
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Since commit 1f2bfbd00e46 ("kbuild: link of vmlinux moved to a
script"), it is easy to increment .version without using a temporary
file .old_version.
I do not see anybody who creates the .tmp_version. Probably it is a
left-over of commit 4e25d8bb9550fb ("[PATCH] kbuild: adjust .version
updating"). Just remove it.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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The thin archives build currently puts all lib.a and built-in.o
files together and links them with --whole-archive.
This works because thin archives can recursively refer to thin
archives. However some architectures include libgcc.a, which may
not be a thin archive, or it may not be constructed with the "P"
option, in which case its contents do not get linked correctly.
So don't pull .a libs into the root built-in.o archive. These
libs should already have symbol tables and indexes built, so they
can be direct linker inputs. Move them out of the --whole-archive
option, which restore the conditional linking behaviour of lib.a
to thin archives builds.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
|
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The P option makes ar do full path name matching and can prevent ar
from discarding files with duplicate names in some cases of creating
thin archives from thin archives. The sh architecture in particular
loses some object files from its kernel/cpu/sh*/ directories without
this option.
This could be a bug in binutils ar, but the P option should not cause
any negative effects so it is safe to use to work around this with.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Close the --whole-archives option with --no-whole-archive. Some
architectures end up including additional .o and files multiple
times after this, and they get duplicate symbols when they are
brought under the --whole-archives option.
This matches more closely with the incremental final link.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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The root built-in.o archive is currently generated before all object
files are built for the final link, due to final build of init/ after
version update. In practice it seems like it doesn't matter because
the archive symbol table does not change, but it is more logical to
create the final archive as the last step.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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kallsyms generation is not foolproof, due to some linkers adding
symbols (e.g., branch trampolines) when a binary size changes.
Have it attempt a 3rd pass automatically if the kallsyms size changes
in the 2nd pass.
This allows powerpc64 allyesconfig to build without adding another
pass when it's not required.
This can be solved other ways by directing the linker not to add labels
on branch stubs, or to move kallsyms near the end of the image. The
former is undesirable for debugging/tracing, and the latter is a more
significant change that requires more testing and review.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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ld -r is an incremental link used to create built-in.o files in build
subdirectories. It produces relocatable object files containing all
its input files, and these are are then pulled together and relocated
in the final link. Aside from the bloat, this constrains the final
link relocations, which has bitten large powerpc builds with
unresolvable relocations in the final link.
Alan Modra has recommended the kernel use thin archives for linking.
This is an alternative and means that the linker has more information
available to it when it links the kernel.
This patch enables a config option architectures can select, which
causes all built-in.o files to be built as thin archives. built-in.o
files in subdirectories do not get symbol table or index attached,
which improves speed and size. The final link pass creates a
built-in.o archive in the root output directory which includes the
symbol table and index. The linker then uses takes this file to link.
The --whole-archive linker option is required, because the linker now
has visibility to every individual object file, and it will otherwise
just completely avoid including those without external references
(consider a file with EXPORT_SYMBOL or initcall or hardware exceptions
as its only entry points). The traditional built works "by luck" as
built-in.o files are large enough that they're going to get external
references. However this optimisation is unpredictable for the kernel
(due to above external references), ineffective at culling unused, and
costly because the .o files have to be searched for references.
Superior alternatives for link-time culling should be used instead.
Build characteristics for inclink vs thinarc, on a small powerpc64le
pseries VM with a modest .config:
inclink thinarc
sizes
vmlinux 15 618 680 15 625 028
sum of all built-in.o 56 091 808 1 054 334
sum excluding root built-in.o 151 430
find -name built-in.o | xargs rm ; time make vmlinux
real 22.772s 21.143s
user 13.280s 13.430s
sys 4.310s 2.750s
- Final kernel pulled in only about 6K more, which shows how
ineffective the object file culling is.
- Build performance looks improved due to less pagecache activity.
On IO constrained systems it could be a bigger win.
- Build size saving is significant.
Side note, the toochain understands archives, so there's some tricks,
$ ar t built-in.o # list all files you linked with
$ size built-in.o # and their sizes
$ objdump -d built-in.o # disassembly (unrelocated) with filenames
Implementation by sfr, minor tweaks by npiggin.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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This patch allows to build the whole kernel with GCC plugins. It was ported from
grsecurity/PaX. The infrastructure supports building out-of-tree modules and
building in a separate directory. Cross-compilation is supported too.
Currently the x86, arm, arm64 and uml architectures enable plugins.
The directory of the gcc plugins is scripts/gcc-plugins. You can use a file or a directory
there. The plugins compile with these options:
* -fno-rtti: gcc is compiled with this option so the plugins must use it too
* -fno-exceptions: this is inherited from gcc too
* -fasynchronous-unwind-tables: this is inherited from gcc too
* -ggdb: it is useful for debugging a plugin (better backtrace on internal
errors)
* -Wno-narrowing: to suppress warnings from gcc headers (ipa-utils.h)
* -Wno-unused-variable: to suppress warnings from gcc headers (gcc_version
variable, plugin-version.h)
The infrastructure introduces a new Makefile target called gcc-plugins. It
supports all gcc versions from 4.5 to 6.0. The scripts/gcc-plugin.sh script
chooses the proper host compiler (gcc-4.7 can be built by either gcc or g++).
This script also checks the availability of the included headers in
scripts/gcc-plugins/gcc-common.h.
The gcc-common.h header contains frequently included headers for GCC plugins
and it has a compatibility layer for the supported gcc versions.
The gcc-generate-*-pass.h headers automatically generate the registration
structures for GIMPLE, SIMPLE_IPA, IPA and RTL passes.
Note that 'make clean' keeps the *.so files (only the distclean or mrproper
targets clean all) because they are needed for out-of-tree modules.
Based on work created by the PaX Team.
Signed-off-by: Emese Revfy <re.emese@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Now that we no longer emit .stubs symbols into a section VMA loaded
at absolute address 0x1000, we can drop the ARM-specific override that
sets a lower limit based on CONFIG_PAGE_OFFSET, below which symbols are
filtered from the kallsyms output.
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Chris Brandt <chris.brandt@renesas.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild
Pull kbuild updates from Michal Marek:
- make dtbs_install fix
- Error handling fix fixdep and link-vmlinux.sh
- __UNIQUE_ID fix for clang
- Fix for if_changed_* to suppress the "is up to date." message
- The kernel is built with -Werror=incompatible-pointer-types
* 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild:
kbuild: Add option to turn incompatible pointer check into error
kbuild: suppress annoying "... is up to date." message
kbuild: fixdep: Check fstat(2) return value
scripts/link-vmlinux.sh: force error on kallsyms failure
Kbuild: provide a __UNIQUE_ID for clang
dtbsinstall: don't move target directory out of the way
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Similar to how relative extables are implemented, it is possible to emit
the kallsyms table in such a way that it contains offsets relative to
some anchor point in the kernel image rather than absolute addresses.
On 64-bit architectures, it cuts the size of the kallsyms address table
in half, since offsets between kernel symbols can typically be expressed
in 32 bits. This saves several hundreds of kilobytes of permanent
.rodata on average. In addition, the kallsyms address table is no
longer subject to dynamic relocation when CONFIG_RELOCATABLE is in
effect, so the relocation work done after decompression now doesn't have
to do relocation updates for all these values. This saves up to 24
bytes (i.e., the size of a ELF64 RELA relocation table entry) per value,
which easily adds up to a couple of megabytes of uncompressed __init
data on ppc64 or arm64. Even if these relocation entries typically
compress well, the combined size reduction of 2.8 MB uncompressed for a
ppc64_defconfig build (of which 2.4 MB is __init data) results in a ~500
KB space saving in the compressed image.
Since it is useful for some architectures (like x86) to retain the
ability to emit absolute values as well, this patch also adds support
for capturing both absolute and relative values when
KALLSYMS_ABSOLUTE_PERCPU is in effect, by emitting absolute per-cpu
addresses as positive 32-bit values, and addresses relative to the
lowest encountered relative symbol as negative values, which are
subtracted from the runtime address of this base symbol to produce the
actual address.
Support for the above is enabled by default for all architectures except
IA-64 and Tile-GX, whose symbols are too far apart to capture in this
manner.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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scripts/kallsyms.c has a special --absolute-percpu command line option
which deals with the zero based per cpu offsets that are used when
building for SMP on x86_64. This means that the option should only be
passed in that case, so add a Kconfig symbol with the correct predicate,
and use that instead.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Since the output of the invocation of scripts/kallsyms is piped directly
into the assembler, error messages it emits are visible on stderr, but
a non-zero return code is ignored, and the build simply proceeds in that
case. However, the resulting kernel is most likely broken, and will crash
at boot.
So instead, capture the output of kallsyms in a separate .S file, and pass
that to the assembler in a separate step.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Similarly to commit fb1770aa78a43530940d0c2dd161e77bc705bdac, with gcc 5
on Ubuntu and CONFIG_STATIC_LINK=y I was seeing these linker errors:
/usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu/librt.a(timer_create.o): In function `__timer_create_new':
(.text+0xcd): undefined reference to `pthread_once'
/usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu/librt.a(timer_create.o): In function `__timer_create_new':
(.text+0x126): undefined reference to `pthread_attr_init'
/usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu/librt.a(timer_create.o): In function `__timer_create_new':
(.text+0x168): undefined reference to `pthread_attr_setdetachstate'
[...]
Obviously we also need -lpthread for librt.a.
Cc: stable@vger.kernel.org # 4.4
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
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On gcc Ubuntu 4.8.4-2ubuntu1~14.04, linking vmlinux fails with:
arch/um/os-Linux/built-in.o: In function `os_timer_create':
/android/kernel/android/arch/um/os-Linux/time.c:51: undefined reference to `timer_create'
arch/um/os-Linux/built-in.o: In function `os_timer_set_interval':
/android/kernel/android/arch/um/os-Linux/time.c:84: undefined reference to `timer_settime'
arch/um/os-Linux/built-in.o: In function `os_timer_remain':
/android/kernel/android/arch/um/os-Linux/time.c:109: undefined reference to `timer_gettime'
arch/um/os-Linux/built-in.o: In function `os_timer_one_shot':
/android/kernel/android/arch/um/os-Linux/time.c:132: undefined reference to `timer_settime'
arch/um/os-Linux/built-in.o: In function `os_timer_disable':
/android/kernel/android/arch/um/os-Linux/time.c:145: undefined reference to `timer_settime'
This is because -lrt appears in the generated link commandline
after arch/um/os-Linux/built-in.o. Fix this by removing -lrt from
arch/um/Makefile and adding it to the UM-specific section of
scripts/link-vmlinux.sh.
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
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