linux/scripts/basic, branch v6.18

integer-wrap: Force full rebuild when .scl file changes

2025-05-08T16:42:06Z

Since the integer wrapping sanitizer's behavior depends on its associated .scl file, we must force a full rebuild if the file changes. If not, instrumentation may differ between targets based on when they were built. Generate a new header file, integer-wrap.h, any time the Clang .scl file changes. Include the header file in compiler-version.h when its associated feature name, INTEGER_WRAP, is defined. This will be picked up by fixdep and force rebuilds where needed. Acked-by: Justin Stitt Link: https://lore.kernel.org/r/20250503184623.2572355-3-kees@kernel.org Reviewed-by: Nicolas Schier Signed-off-by: Kees Cook

fixdep: use xmalloc()

2024-09-01T11:34:49Z

When malloc() fails, there is not much userspace programs can do. xmalloc() is useful to bail out on a memory allocation failure. Signed-off-by: Masahiro Yamada

kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursion

2023-06-22T12:21:06Z

When CONFIG_TRIM_UNUSED_KSYMS is enabled, Kbuild recursively traverses the directory tree to determine which EXPORT_SYMBOL to trim. If an EXPORT_SYMBOL turns out to be unused by anyone, Kbuild begins the second traverse, where some source files are recompiled with their EXPORT_SYMBOL() tuned into a no-op. Linus stated negative opinions about this slowness in commits: - 5cf0fd591f2e ("Kbuild: disable TRIM_UNUSED_KSYMS option") - a555bdd0c58c ("Kbuild: enable TRIM_UNUSED_KSYMS again, with some guarding") We can do this better now. The final data structures of EXPORT_SYMBOL are generated by the modpost stage, so modpost can selectively emit KSYMTAB entries that are really used by modules. Commit f73edc8951b2 ("kbuild: unify two modpost invocations") is another ground-work to do this in a one-pass algorithm. With the list of modules, modpost sets sym->used if it is used by a module. modpost emits KSYMTAB only for symbols with sym->used==true. BTW, Nicolas explained why the trimming was implemented with recursion: https://lore.kernel.org/all/2o2rpn97-79nq-p7s2-nq5-8p83391473r@syhkavp.arg/ Actually, we never achieved that level of optimization where the chain reaction of trimming comes into play because: - CONFIG_LTO_CLANG cannot remove any unused symbols - CONFIG_LD_DEAD_CODE_DATA_ELIMINATION is enabled only for vmlinux, but not modules If deeper trimming is required, we need to revisit this, but I guess that is unlikely to happen. Signed-off-by: Masahiro Yamada

fixdep: do not parse .rlib, .rmeta, *.so

2023-01-22T14:43:33Z

fixdep is designed only for parsing text files. read_file() appends a terminating null byte ('\0') and parse_config_file() calls strstr() to search for CONFIG options. rustc outputs *.rlib, *.rmeta, *.so to dep-info. fixdep needs them in the dependency, but there is no point in parsing such binary files. Signed-off-by: Masahiro Yamada Reviewed-by: Miguel Ojeda Tested-by: Miguel Ojeda

fixdep: avoid parsing the same file over again

2023-01-22T14:43:33Z

The dep files (*.d files) emitted by C compilers usually contain the deduplicated list of included files. One exceptional case is when a header is included by the -include command line option, and also by #include directive. For example, the top Makefile adds the command line option, "-include $(srctree)/include/linux/kconfig.h". You do not need to include in every source file. In fact, include/linux/kconfig.h is listed twice in many .*.cmd files due to include/linux/xarray.h having "#include ". I did not fix that since it is a small redundancy. However, this is more annoying for rustc. rustc emits the dependency for each emission type. For example, cmd_rustc_library emits dep-info, obj, and metadata. So, the emitted *.d file contains the dependency for those 3 targets, which makes fixdep parse the same file 3 times. $ grep rust/alloc/raw_vec.rs rust/.alloc.o.cmd rust/alloc/raw_vec.rs \ rust/alloc/raw_vec.rs \ rust/alloc/raw_vec.rs \ To skip the second parsing, this commit adds a hash table for parsed files, just like we did for CONFIG options. Signed-off-by: Masahiro Yamada Acked-by: Miguel Ojeda Tested-by: Miguel Ojeda Reviewed-by: Vincenzo Palazzo

fixdep: refactor hash table lookup

2023-01-22T14:43:33Z

Change the hash table code so it will be easier to add the second table. Signed-off-by: Masahiro Yamada Reviewed-by: Miguel Ojeda Tested-by: Miguel Ojeda

fixdep: parse Makefile more correctly to handle comments etc.

2023-01-22T14:43:33Z

fixdep parses dependency files (*.d) emitted by the compiler. *.d files are Makefiles describing the dependencies of the main source file. fixdep understands minimal Makefile syntax. It works well enough for GCC and Clang, but not for rustc. This commit improves the parser a little more for better processing comments, escape sequences, etc. My main motivation is to drop comments. rustc may output comments (e.g. env-dep). Currentyly, rustc build rules invoke sed to remove comments, but it is more efficient to do it in fixdep. Signed-off-by: Masahiro Yamada Acked-by: Miguel Ojeda Tested-by: Miguel Ojeda

kbuild: rename cmd_$@ to savedcmd_$@ in *.cmd files

2023-01-22T14:43:33Z

The cmd-check macro compares $(cmd_$@) and $(cmd_$1), but a pitfall is that you cannot use cmd_ as the variable name for the command. For example, the following code will not work in the top Makefile or ./Kbuild. quiet_cmd_foo = GEN $@ cmd_foo = touch $@ targets += foo foo: FORCE $(call if_changed,foo) In this case, both $@ and $1 are expanded to 'foo', so $(cmd_check) is always empty. We do not need to use the same prefix for cmd_$@ and cmd_$1. Rename the former to savedcmd_$@. Signed-off-by: Masahiro Yamada Reviewed-by: Nicolas Schier

fixdep: remove unneeded inclusion

2022-12-30T08:26:19Z

This is unneeded since commit 69304379ff03 ("fixdep: use fflush() and ferror() to ensure successful write to files"). Signed-off-by: Masahiro Yamada

randstruct: Move seed generation into scripts/basic/

2022-05-08T08:33:07Z

To enable Clang randstruct support, move the structure layout randomization seed generation out of scripts/gcc-plugins/ into scripts/basic/ so it happens early enough that it can be used by either compiler implementation. The gcc-plugin still builds its own header file, but now does so from the common "randstruct.seed" file. Cc: linux-hardening@vger.kernel.org Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20220503205503.3054173-6-keescook@chromium.org

linux/scripts/basic, branch v6.18

integer-wrap: Force full rebuild when .scl file changes

fixdep: use xmalloc()

kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursion

fixdep: do not parse *.rlib, *.rmeta, *.so

fixdep: avoid parsing the same file over again

fixdep: refactor hash table lookup

fixdep: parse Makefile more correctly to handle comments etc.

kbuild: rename cmd_$@ to savedcmd_$@ in *.cmd files

fixdep: remove unneeded inclusion

randstruct: Move seed generation into scripts/basic/

fixdep: do not parse .rlib, .rmeta, *.so