user/sven/linux.git/scripts/link-vmlinux.sh, branch v5.4.38

bpf, btf: Always output invariant hit in pahole DWARF to BTF transform

2020-02-24T07:36:55Z

[ Upstream commit 2a67a6ccb01f21b854715d86ff6432a18b97adb3 ] 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 Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20200122000110.GA310073@chrisdown.name Signed-off-by: Sasha Levin

bpf: Force .BTF section start to zero when dumping from vmlinux

2020-01-26T09:00:58Z

commit df786c9b947639aedbc7bb44b5dae2a7824af360 upstream. 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 Signed-off-by: Daniel Borkmann Acked-by: John Fastabend Cc: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20191127225759.39923-1-sdf@google.com Signed-off-by: Greg Kroah-Hartman

bpf: Support pre-2.25-binutils objcopy for vmlinux BTF

2020-01-17T18:48:41Z

commit da5fb18225b49b97bb37c51bcbbb2990a507c364 upstream. 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 Signed-off-by: Alexei Starovoitov Tested-by: Andrii Nakryiko Acked-by: Andrii Nakryiko Cc: John Fastabend Link: https://lore.kernel.org/bpf/20191127161410.57327-1-sdf@google.com Signed-off-by: Greg Kroah-Hartman

Merge tag 'kbuild-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2019-09-20T15:36:47Z

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_.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_.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 ...

kbuild: replace BASH-specific ${@:2} with shift and ${@}

2019-09-06T16:51:55Z

${@: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 Fixes: 341dfcf8d78e ("btf: expose BTF info through sysfs") Cc: Stephen Rothwell Cc: Masahiro Yamada Signed-off-by: Andrii Nakryiko Acked-by: Yonghong Song Reviewed-by: Masahiro Yamada Signed-off-by: Alexei Starovoitov

btf: do not use CONFIG_OUTPUT_FORMAT

2019-08-21T12:57:17Z

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 Signed-off-by: Daniel Borkmann

kbuild: Parameterize kallsyms generation and correct reporting

2019-08-21T12:05:21Z

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 Signed-off-by: Masahiro Yamada

Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

2019-08-13T23:24:57Z

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

btf: rename /sys/kernel/btf/kernel into /sys/kernel/btf/vmlinux

2019-08-13T21:19:42Z

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 Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann

btf: expose BTF info through sysfs

2019-08-13T14:14:15Z

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/ 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 Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann