linux/scripts/link-vmlinux.sh, branch v6.3

kallsyms: Correctly sequence symbols when CONFIG_LTO_CLANG=y

2022-11-13T02:47:36Z

LLVM appends various suffixes for local functions and variables, suffixes observed: - foo.llvm.[0-9a-f]+ - foo.[0-9a-f]+ Therefore, when CONFIG_LTO_CLANG=y, kallsyms_lookup_name() needs to truncate the suffix of the symbol name before comparing the local function or variable name. Old implementation code: - if (strcmp(namebuf, name) == 0) - return kallsyms_sym_address(i); - if (cleanup_symbol_name(namebuf) && strcmp(namebuf, name) == 0) - return kallsyms_sym_address(i); The preceding process is traversed by address from low to high. That is, for those with the same name after the suffix is removed, the one with the smallest address is returned first. Therefore, when sorting in the tool, if the raw names are the same, they should be sorted by address in ascending order. ASCII[.] = 2e ASCII[0-9] = 30,39 ASCII[A-Z] = 41,5a ASCII[_] = 5f ASCII[a-z] = 61,7a According to the preceding ASCII code values, the following sorting result is strictly followed. --------------------------------- | main-key | sub-key | |---------------------------------| | | addr_lowest | | | ... | | . | ... | | | addr_highest | |---------------------------------| | ? | | //? is [_A-Za-z0-9] --------------------------------- Signed-off-by: Zhen Lei Signed-off-by: Luis Chamberlain

kbuild: rebuild .vmlinux.export.o when its prerequisite is updated

2022-10-02T18:52:58Z

When include/linux/export-internal.h is updated, .vmlinux.export.o must be rebuilt, but it does not happen because its rule is hidden behind scripts/link-vmlinux.sh. Move it out of the shell script, so that Make can see the dependency between vmlinux and .vmlinux.export.o. Move the vmlinux rule to scripts/Makefile.vmlinux. Signed-off-by: Masahiro Yamada

kbuild: move modules.builtin(.modinfo) rules to Makefile.vmlinux_o

2022-10-02T18:52:58Z

Do not build modules.builtin(.modinfo) as a side-effect of vmlinux. There are no good reason to rebuild them just because any of vmlinux's prerequistes (vmlinux.lds, .vmlinux.export.c, etc.) has been updated. Signed-off-by: Masahiro Yamada

kallsyms: take the input file instead of reading stdin

2022-10-02T09:06:05Z

This gets rid of the pipe operator connected with 'cat'. Also use getopt_long() to parse the command line. Signed-off-by: Masahiro Yamada

kbuild: reuse mksysmap output for kallsyms

2022-10-02T09:06:05Z

scripts/mksysmap internally runs ${NM} (dropping some symbols). When CONFIG_KALLSYMS=y, mksysmap creates .tmp_System.map, but it is almost the same as the output from the ${NM} invocation in kallsyms(). It is true scripts/mksysmap drops some symbols, but scripts/kallsyms.c ignores more anyway. Keep the mksysmap output as *.syms, and reuse it for kallsyms and 'cmp -s'. It saves one ${NM} invocation. Signed-off-by: Masahiro Yamada

kbuild: use obj-y instead extra-y for objects placed at the head

2022-10-02T09:04:05Z

The objects placed at the head of vmlinux need special treatments: - arch/$(SRCARCH)/Makefile adds them to head-y in order to place them before other archives in the linker command line. - arch/$(SRCARCH)/kernel/Makefile adds them to extra-y instead of obj-y to avoid them going into built-in.a. This commit gets rid of the latter. Create vmlinux.a to collect all the objects that are unconditionally linked to vmlinux. The objects listed in head-y are moved to the head of vmlinux.a by using 'ar m'. With this, arch/$(SRCARCH)/kernel/Makefile can consistently use obj-y for builtin objects. There is no *.o that is directly linked to vmlinux. Drop unneeded code in scripts/clang-tools/gen_compile_commands.py. $(AR) mPi needs 'T' to workaround the llvm-ar bug. The fix was suggested by Nathan Chancellor [1]. [1]: https://lore.kernel.org/llvm/YyjjT5gQ2hGMH0ni@dev-arch.thelio-3990X/ Signed-off-by: Masahiro Yamada Tested-by: Nick Desaulniers Reviewed-by: Nicolas Schier

kbuild: unify two modpost invocations

2022-09-28T21:07:58Z

Currently, modpost is executed twice; first for vmlinux, second for modules. This commit merges them. Current build flow ================== 1) build obj-y and obj-m objects 2) link vmlinux.o 3) modpost for vmlinux 4) link vmlinux 5) modpost for modules 6) link modules (*.ko) The build steps 1) through 6) are serialized, that is, modules are built after vmlinux. You do not get benefits of parallel builds when scripts/link-vmlinux.sh is being run. New build flow ============== 1) build obj-y and obj-m objects 2) link vmlinux.o 3) modpost for vmlinux and modules 4a) link vmlinux 4b) link modules (*.ko) In the new build flow, modpost is invoked just once. vmlinux and modules are built in parallel. One exception is CONFIG_DEBUG_INFO_BTF_MODULES=y, where modules depend on vmlinux. Signed-off-by: Masahiro Yamada Tested-by: Nick Desaulniers Reviewed-by: Nicolas Schier

kbuild: move vmlinux.o rule to the top Makefile

2022-09-28T19:42:34Z

Move the build rules of vmlinux.o out of scripts/link-vmlinux.sh to clearly separate 1) pre-modpost, 2) modpost, 3) post-modpost stages. This will make further refactoring possible. Signed-off-by: Masahiro Yamada Tested-by: Nick Desaulniers Reviewed-by: Nicolas Schier

kbuild: move .vmlinux.objs rule to Makefile.modpost

2022-09-28T19:42:00Z

.vmlinux.objs is used by modpost, so scripts/Makefile.modpost is a better place to generate it. It is used only when CONFIG_MODVERSIONS=y. It should be guarded by "ifdef CONFIG_MODVERSIONS". Signed-off-by: Masahiro Yamada Tested-by: Nick Desaulniers Reviewed-by: Nicolas Schier

kbuild: build init/built-in.a just once

2022-09-28T19:40:15Z

Kbuild builds init/built-in.a twice; first during the ordinary directory descending, second from scripts/link-vmlinux.sh. We do this because UTS_VERSION contains the build version and the timestamp. We cannot update it during the normal directory traversal since we do not yet know if we need to update vmlinux. UTS_VERSION is temporarily calculated, but omitted from the update check. Otherwise, vmlinux would be rebuilt every time. When Kbuild results in running link-vmlinux.sh, it increments the version number in the .version file and takes the timestamp at that time to really fix UTS_VERSION. However, updating the same file twice is a footgun. To avoid nasty timestamp issues, all build artifacts that depend on init/built-in.a are atomically generated in link-vmlinux.sh, where some of them do not need rebuilding. To fix this issue, this commit changes as follows: [1] Split UTS_VERSION out to include/generated/utsversion.h from include/generated/compile.h include/generated/utsversion.h is generated just before the vmlinux link. It is generated under include/generated/ because some decompressors (s390, x86) use UTS_VERSION. [2] Split init_uts_ns and linux_banner out to init/version-timestamp.c from init/version.c init_uts_ns and linux_banner contain UTS_VERSION. During the ordinary directory descending, they are compiled with __weak and used to determine if vmlinux needs relinking. Just before the vmlinux link, they are compiled without __weak to embed the real version and timestamp. Signed-off-by: Masahiro Yamada