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2020-03-19bpf: Support llvm-objcopy for vmlinux BTFFangrui Song
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
2020-03-04kbuild: Remove debug info from kallsyms linkingKees Cook
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
2020-02-11kbuild: fix mismatch between .version and include/generated/compile.hMasahiro Yamada
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>
2020-02-01Merge tag 'kbuild-v5.6' of ↵Linus Torvalds
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 ...
2020-01-28Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextLinus Torvalds
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 ...
2020-01-22bpf, btf: Always output invariant hit in pahole DWARF to BTF transformChris Down
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
2020-01-07kbuild: create modules.builtin without Makefile.modbuiltin or tristate.confMasahiro Yamada
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>
2019-12-13x86/unwind/orc: Remove boot-time ORC unwind tables sortingShile Zhang
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>
2019-12-13scripts/sorttable: Rename 'sortextable' to 'sorttable'Shile Zhang
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>
2019-11-29bpf: Force .BTF section start to zero when dumping from vmlinuxStanislav Fomichev
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
2019-11-27bpf: Support pre-2.25-binutils objcopy for vmlinux BTFStanislav Fomichev
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
2019-09-20Merge tag 'kbuild-v5.4' of ↵Linus Torvalds
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 ...
2019-09-06kbuild: replace BASH-specific ${@:2} with shift and ${@}Andrii Nakryiko
${@: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>
2019-08-21btf: do not use CONFIG_OUTPUT_FORMATIlya Leoshkevich
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>
2019-08-21kbuild: Parameterize kallsyms generation and correct reportingKees Cook
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>
2019-08-13Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-nextJakub Kicinski
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>
2019-08-13btf: rename /sys/kernel/btf/kernel into /sys/kernel/btf/vmlinuxAndrii Nakryiko
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>
2019-08-13btf: expose BTF info through sysfsAndrii Nakryiko
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>
2019-08-01kbuild: modpost: do not parse unnecessary rules for vmlinux modpostMasahiro Yamada
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 $(MODVERDIR)/*.mod") Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-05-08Merge tag 'kbuild-v5.2' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull Kbuild updates from Masahiro Yamada: - allow users to invoke 'make' out of the source tree - refactor scripts/mkmakefile - deprecate KBUILD_SRC, which was used to track the source tree location for O= build. - fix recordmcount.pl in case objdump output is localized - turn unresolved symbols in external modules to errors from warnings by default; pass KBUILD_MODPOST_WARN=1 to get them back to warnings - generate modules.builtin.modinfo to collect .modinfo data from built-in modules - misc Makefile cleanups * tag 'kbuild-v5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (21 commits) .gitignore: add more all*.config patterns moduleparam: Save information about built-in modules in separate file Remove MODULE_ALIAS() calls that take undefined macro .gitignore: add leading and trailing slashes to generated directories scripts/tags.sh: fix direct execution of scripts/tags.sh scripts: override locale from environment when running recordmcount.pl samples: kobject: allow CONFIG_SAMPLE_KOBJECT to become y samples: seccomp: turn CONFIG_SAMPLE_SECCOMP into a bool option kbuild: move Documentation to vmlinux-alldirs kbuild: move samples/ to KBUILD_VMLINUX_OBJS modpost: make KBUILD_MODPOST_WARN also configurable for external modules kbuild: check arch/$(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'" ...
2019-05-07moduleparam: Save information about built-in modules in separate fileAlexey Gladkov
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>
2019-05-06kbuild: tolerate missing pahole when generating BTFAndrii Nakryiko
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>
2019-04-16kbuild: handle old pahole more gracefully when generating BTFAndrii Nakryiko
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>
2019-04-03kbuild: add ability to generate BTF type info for vmlinuxAndrii Nakryiko
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>
2019-03-14kbuild: source include/config/auto.conf instead of ${KCONFIG_CONFIG}Masahiro Yamada
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>
2019-01-28kbuild: merge KBUILD_VMLINUX_{INIT,MAIN} into KBUILD_VMLINUX_OBJSMasahiro Yamada
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>
2019-01-28kbuild: remove top-level built-in.aMasahiro Yamada
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>
2018-08-24kbuild: rename LDFLAGS to KBUILD_LDFLAGSMasahiro Yamada
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>
2018-05-17kallsyms: remove symbol prefix supportMasahiro Yamada
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>
2018-03-26kbuild: Use ls(1) instead of stat(1) to obtain file sizeMichael Forney
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>
2018-03-26kbuild: rename built-in.o to built-in.aNicholas Piggin
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>
2018-03-26kbuild: remove incremental linking optionNicholas Piggin
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>
2018-03-02kbuild: drop superfluous GCC_PLUGINS_CFLAGS assignmentCao jin
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>
2017-11-17Merge tag 'kbuild-v4.15' of ↵Linus Torvalds
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 ...
2017-11-02License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman
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>
2017-10-09kbuild: link-vmlinux.sh: simplify .version incrementMasahiro Yamada
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>
2017-06-30kbuild: handle libs-y archives separately from built-in.o archivesNicholas Piggin
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>
2017-06-30kbuild: thin archives use P option to arNicholas Piggin
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>
2017-06-30kbuild: thin archives final link close --whole-archives optionNicholas Piggin
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>
2016-11-29kbuild: minor improvement for thin archives buildNicholas Piggin
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>
2016-11-29kbuild: kallsyms allow 3-pass generation if symbols size has changedNicholas Piggin
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>
2016-09-09kbuild: allow architectures to use thin archives instead of ld -rStephen Rothwell
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>
2016-06-07GCC plugin infrastructureEmese Revfy
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>
2016-04-07ARM: 8552/1: kallsyms: remove special lower address limit for CONFIG_ARMArd Biesheuvel
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>
2016-03-24Merge branch 'kbuild' of ↵Linus Torvalds
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
2016-03-15kallsyms: add support for relative offsets in kallsyms address tableArd Biesheuvel
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>
2016-03-15x86: kallsyms: disable absolute percpu symbols on !SMPArd Biesheuvel
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>
2016-02-08scripts/link-vmlinux.sh: force error on kallsyms failureArd Biesheuvel
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>
2016-01-10um: link with -lpthreadVegard Nossum
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>
2015-12-08arch: um: fix error when linking vmlinux.Lorenzo Colitti
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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