Masahiro Yamada 5e9e95cc91 kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursion ... 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: - 5cf0fd591f ("Kbuild: disable TRIM_UNUSED_KSYMS option") - a555bdd0c5 ("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 f73edc8951 ("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 <masahiroy@kernel.org>		2023-06-22 21:21:06 +09:00
..
atomic	locking/atomic: Correct (cmp)xchg() instrumentation	2023-04-29 09:09:31 +02:00
basic	kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursion	2023-06-22 21:21:06 +09:00
clang-tools	scripts: handle BrokenPipeError for python scripts	2023-01-26 12:43:33 +09:00
coccinelle	coccinelle: api/atomic_as_refcounter: include message type in output	2022-12-26 21:47:12 +01:00
dtc	dts: add riscv include prefix link	2023-03-27 22:45:22 +02:00
dummy-tools
gcc-plugins	Merge branch 'for-linus/hardening' into for-next/hardening	2023-02-02 18:43:28 +00:00
gdb	Mainly singleton patches all over the place. Series of note are:	2023-04-27 19:57:00 -07:00
genksyms
kconfig	streamline_config.pl: handle also ${CONFIG_FOO}	2023-06-08 11:11:32 +09:00
ksymoops
mod	kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursion	2023-06-22 21:21:06 +09:00
package	Kbuild updates for v6.4	2023-04-30 11:32:53 -07:00
selinux
tracing	tracing: Always use canonical ftrace path	2023-02-18 14:34:09 -05:00
.gitignore	kbuild: use git-archive for source package creation	2023-03-16 22:46:12 +09:00
as-version.sh	kbuild: Update assembler calls to use proper flags and language target	2023-01-26 12:41:38 +09:00
asn1_compiler.c	ASN.1: Fix check for strdup() success	2023-04-21 08:58:00 -07:00
bloat-o-meter	scripts/bloat-o-meter: use the reverse flag for sort	2023-02-02 22:50:03 -08:00
bootgraph.pl
bpf_doc.py	bpf: Remove extra whitespace in SPDX tag for syscall/helpers man pages	2023-04-11 17:45:57 +02:00
cc-can-link.sh
cc-version.sh	scripts: Remove ICC-related dead code	2023-04-24 10:18:32 -07:00
check_extable.sh
check-git	kbuild: use git-archive for source package creation	2023-03-16 22:46:12 +09:00
check-sysctl-docs	sysctl: remove register_sysctl_paths()	2023-05-02 19:24:16 -07:00
checkdeclares.pl
checkincludes.pl
checkkconfigsymbols.py	scripts: handle BrokenPipeError for python scripts	2023-01-26 12:43:33 +09:00
checkpatch.pl	Mainly singleton patches all over the place. Series of note are:	2023-04-27 19:57:00 -07:00
checkstack.pl	sh: remove sh5/sh64 last fragments	2023-03-23 10:02:02 +01:00
checksyscalls.sh	checksyscalls: ignore fstat to silence build warning on LoongArch	2023-03-23 17:18:32 -07:00
checkversion.pl
cleanfile
cleanpatch
coccicheck	scripts: coccicheck: Use /usr/bin/env	2023-02-25 20:11:06 +01:00
config
const_structs.checkpatch	const_structs.checkpatch.pl: add kobj_type	2023-02-08 13:33:29 +01:00
decode_stacktrace.sh
decodecode	scripts/decodecode: Add support for RISC-V	2023-02-21 16:53:54 -08:00
depmod.sh
dev-needs.sh
diffconfig	scripts: handle BrokenPipeError for python scripts	2023-01-26 12:43:33 +09:00
documentation-file-ref-check
export_report.pl
extract_xc3028.pl
extract-ikconfig
extract-module-sig.pl
extract-sys-certs.pl
extract-vmlinux
faddr2line	scripts/faddr2line: Fix regression in name resolution on ppc64le	2022-11-16 10:42:10 +01:00
file-size.sh
find-unused-docs.sh
gcc-x86_32-has-stack-protector.sh
gcc-x86_64-has-stack-protector.sh
gen-randstruct-seed.sh
generate_initcall_order.pl
generate_rust_analyzer.py	scripts: generate_rust_analyzer: Handle sub-modules with no Makefile	2023-04-07 00:53:34 +02:00
generate_rust_target.rs
get_abi.pl
get_dvb_firmware
get_feat.pl
get_maintainer.pl
gfp-translate
head-object-list.txt	scripts/head-object-list: Remove x86 from the list	2023-01-09 18:22:21 +01:00
headerdep.pl
headers_install.sh	scripts: Update the CONFIG_* ignore list in headers_install.sh	2023-03-10 21:05:16 +01:00
insert-sys-cert.c
install.sh
is_rust_module.sh	rust: fix regexp in scripts/is_rust_module.sh	2023-04-19 19:28:49 +02:00
jobserver-exec	scripts: support GNU make 4.4 in jobserver-exec	2023-01-16 20:15:20 +09:00
kallsyms.c	scripts/kallsyms: remove KSYM_NAME_LEN_BUFFER	2023-06-15 04:47:04 +09:00
Kbuild.include	kbuild: replace $(dot-target).tmp in filechk with $(tmp-target)	2023-01-22 23:43:33 +09:00
Kconfig.include	kbuild: Update assembler calls to use proper flags and language target	2023-01-26 12:41:38 +09:00
kernel-doc	kernel-doc: don't let V=1 change outcome	2023-06-10 16:39:02 +09:00
ld-version.sh
leaking_addresses.pl	leaking_addresses: also skip canonical ftrace path	2023-03-29 06:52:08 -04:00
Lindent
link-vmlinux.sh	Kbuild updates for v6.4	2023-04-30 11:32:53 -07:00
Makefile	kbuild: use git-archive for source package creation	2023-03-16 22:46:12 +09:00
Makefile.asm-generic	kbuild: add kbuild-file macro	2022-11-22 23:40:02 +09:00
Makefile.build	kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursion	2023-06-22 21:21:06 +09:00
Makefile.clang	kbuild: add $(CLANG_FLAGS) to KBUILD_CPPFLAGS	2023-06-05 09:50:44 +09:00
Makefile.clean	kbuild: add kbuild-file macro	2022-11-22 23:40:02 +09:00
Makefile.compiler	kbuild: Add KBUILD_CPPFLAGS to as-option invocation	2023-06-07 22:41:08 +09:00
Makefile.debug	Makefile.debug: support for -gz=zstd	2022-11-21 10:18:39 +09:00
Makefile.defconf	kbuild: Provide a version of merge_into_defconfig without override warnings	2023-02-13 20:18:28 +01:00
Makefile.dtbinst	kbuild: add kbuild-file macro	2022-11-22 23:40:02 +09:00
Makefile.extrawarn	kbuild: add -Wundef to KBUILD_CPPFLAGS for W=1 builds	2022-12-11 17:28:32 +09:00
Makefile.gcc-plugins
Makefile.headersinst
Makefile.host	kbuild: remove sed commands after rustc rules	2023-01-22 23:43:33 +09:00
Makefile.kasan	kasan: remove hwasan-kernel-mem-intrinsic-prefix=1 for clang-14	2023-04-18 16:29:43 -07:00
Makefile.kcov
Makefile.kcsan
Makefile.kmsan
Makefile.lib	kbuild: Disallow DTB overlays to built from .dts named source files	2023-05-22 10:34:37 +09:00
Makefile.modfinal	kbuild: rename cmd_$@ to savedcmd_$@ in *.cmd files	2023-01-22 23:43:33 +09:00
Makefile.modinst	modules-6.3-rc1	2023-02-23 14:05:08 -08:00
Makefile.modpost	kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursion	2023-06-22 21:21:06 +09:00
Makefile.package	Kbuild updates for v6.4	2023-04-30 11:32:53 -07:00
Makefile.randstruct
Makefile.ubsan
Makefile.userprogs
Makefile.vmlinux	kbuild: Fix CFI hash randomization with KASAN	2023-01-13 15:22:03 -08:00
Makefile.vmlinux_o
makelst
markup_oops.pl
min-tool-version.sh	Remove Intel compiler support	2023-03-05 10:49:37 -08:00
misc-check	kbuild: make W=1 warn files that are tracked but ignored by git	2023-01-22 23:43:33 +09:00
mkcompile_h
mksysmap	scripts/mksysmap: Ignore __pi_ local arm64 symbols	2023-06-07 22:41:08 +09:00
mkuboot.sh
module.lds.S	arm64: unwind: add asynchronous unwind tables to kernel and modules	2022-11-09 18:06:35 +00:00
modules-check.sh	kbuild: change module.order to list *.o instead of *.ko	2022-12-14 15:42:40 +09:00
nsdeps
objdiff
objdump-func	scripts/objdump-func: Support multiple functions	2023-04-14 16:08:28 +02:00
pahole-flags.sh	btf, scripts: Exclude Rust CUs with pahole	2023-01-17 17:29:42 +01:00
pahole-version.sh
parse-maintainers.pl
patch-kernel
profile2linkerlist.pl
prune-kernel
recordmcount.c	recordmcount: Fix memory leaks in the uwrite function	2023-04-25 21:10:20 -04:00
recordmcount.h
recordmcount.pl
relocs_check.sh	powerpc: Move script to check relocations at compile time in scripts/	2023-04-19 07:46:31 -07:00
remove-stale-files	kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursion	2023-06-22 21:21:06 +09:00
rust_is_available_bindgen_libclang.h
rust_is_available.sh
setlocalversion	kbuild: use git-archive for source package creation	2023-03-16 22:46:12 +09:00
show_delta
sign-file.c
sorttable.c	LoongArch: extable: Add type and data fields	2022-12-14 08:36:11 +08:00
sorttable.h	x86,objtool: Split UNWIND_HINT_EMPTY in two	2023-03-23 23:18:58 +01:00
spdxcheck-test.sh
spdxcheck.py
spdxexclude
spelling.txt	scripts/spelling.txt: add "exsits" pattern and fix typo instances	2023-02-02 22:50:07 -08:00
sphinx-pre-install	docs: sphinx-pre-install: don't require the RTD theme	2022-10-13 11:14:43 -06:00
split-man.pl
stackdelta
stackusage
subarch.include
syscallhdr.sh
syscallnr.sh
syscalltbl.sh
tags.sh	scripts/tags.sh: Resolve gtags empty index generation	2023-05-22 10:34:38 +09:00
test_fortify.sh
tools-support-relr.sh	Makefile: use -z pack-relative-relocs	2023-04-17 11:23:06 +09:00
unifdef.c
ver_linux
xen-hypercalls.sh
xz_wrap.sh