By default, libucontext should build with UNPREFIXED_SYMBOLS := yes, according to the Makefile, however due to Gentoo's override of CFLAGS and an unconventional approach of using -DUNPREFIXED_SYMBOLS to indicate the option, libucontext will not build with these symbols enabled and programs which expect their presence (tbb, mold) will fail to link. The attached patch side-steps the issue by directly adding "-DUNPREFIXED_SYMBOLS" after ${CFLAGS} for each object. An alternative would be to modify the EBUILD to not override the CFLAGS, however this may be undesirable if, for ex. cross-compiling. Reproducible: Always Steps to Reproduce: 1. Build sys-libs/libucontext on a Gentoo musl system (should also occur on glibc, but this is not a target of libucontext). 2. Use objtool -T or alternative on /usr/lib/libucontext.so : note the lack of unprefixed / weak symbols. 3. Attempt to build a package such as sys-devel/mold. Actual Results: Regardless of the status of -lucontext, the ebuild fails, since the weak symbols getcontext and makecontext where never included in the libucontext.so shared object. Expected Results: The ebuild, as long as it is aware of the need for -lucontext (see related musl bug), should succeed, and the linker should find the necessary symbols. Note: this is in a chroot with /var/db/repos shared between the host and chroot to reduce network usage and sync frequency. A patch will be attached shortly after this report is filed. Portage 3.0.30 (python 3.9.9-final-0, default/linux/amd64/17.0/musl, gcc-11.2.0, musl-1.2.2-r6, 5.15.16-gentoo x86_64) ================================================================= System uname: Linux-5.15.16-gentoo-x86_64-Intel-R-_Xeon-R-_E-2176G_CPU_@_3.70GHz-with-libc KiB Mem: 65754876 total, 47896824 free KiB Swap: 67108860 total, 67108860 free Timestamp of repository gentoo: Fri, 04 Feb 2022 00:08:10 +0000 Timestamp of repository guru: Tue, 01 Feb 2022 18:53:09 +0000 Timestamp of repository musl: Tue, 01 Feb 2022 18:38:21 +0000 Head commit of repository musl: cf8d4bb7e03c02a8879bc8b73c8b807ec64d9229 sh bash 5.1_p8 ld GNU ld (Gentoo 2.37_p1 p0) 2.37 app-misc/pax-utils: 1.3.3::gentoo app-shells/bash: 5.1_p8::gentoo dev-lang/perl: 5.34.0-r6::gentoo dev-lang/python: 3.9.9-r1::gentoo, 3.10.0_p1-r1::gentoo dev-lang/rust: 1.58.1::musl dev-util/cmake: 3.21.4::gentoo dev-util/meson: 0.60.3::gentoo sys-apps/baselayout: 2.7-r3::gentoo sys-apps/openrc: 0.44.10::gentoo sys-apps/sandbox: 2.25::gentoo sys-devel/autoconf: 2.13-r1::gentoo, 2.71-r1::gentoo sys-devel/automake: 1.16.4::gentoo sys-devel/binutils: 2.37_p1::gentoo sys-devel/binutils-config: 5.4::gentoo sys-devel/clang: 13.0.0::gentoo sys-devel/gcc: 11.2.0::gentoo sys-devel/gcc-config: 2.5-r1::gentoo sys-devel/libtool: 2.4.6-r6::gentoo sys-devel/lld: 13.0.0::gentoo sys-devel/llvm: 13.0.0::gentoo sys-devel/make: 4.3::gentoo sys-kernel/linux-headers: 5.15-r3::gentoo (virtual/os-headers) sys-libs/musl: 1.2.2-r6::gentoo Repositories: gentoo location: /var/db/repos/gentoo sync-type: rsync sync-uri: rsync://rsync.gentoo.org/gentoo-portage priority: -1000 sync-rsync-extra-opts: sync-rsync-verify-jobs: 1 sync-rsync-verify-max-age: 24 sync-rsync-verify-metamanifest: yes guru location: /var/db/repos/guru masters: gentoo musl location: /var/db/repos/musl sync-type: git sync-uri: https://github.com/gentoo-mirror/musl.git masters: gentoo ACCEPT_KEYWORDS="amd64" ACCEPT_LICENSE="@FREE" CBUILD="x86_64-unknown-linux-musl" CFLAGS="-march=native -O2 -pipe" CHOST="x86_64-unknown-linux-musl" CONFIG_PROTECT="/etc /usr/lib64/libreoffice/program/sofficerc /usr/share/gnupg/qualified.txt" CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/dconf /etc/env.d /etc/fonts/fonts.conf /etc/gconf /etc/gentoo-release /etc/revdep-rebuild /etc/sandbox.d /etc/terminfo" CXXFLAGS="-march=native -O2 -pipe" DISTDIR="/var/cache/distfiles" ENV_UNSET="CARGO_HOME DBUS_SESSION_BUS_ADDRESS DISPLAY GOBIN GOPATH PERL5LIB PERL5OPT PERLPREFIX PERL_CORE PERL_MB_OPT PERL_MM_OPT XAUTHORITY XDG_CACHE_HOME XDG_CONFIG_HOME XDG_DATA_HOME XDG_RUNTIME_DIR" FCFLAGS="-march=native -O2 -pipe" FEATURES="assume-digests binpkg-docompress binpkg-dostrip binpkg-logs buildpkg-live config-protect-if-modified distlocks ebuild-locks fixlafiles ipc-sandbox merge-sync network-sandbox news parallel-fetch pid-sandbox preserve-libs protect-owned qa-unresolved-soname-deps sandbox sfperms strict unknown-features-warn unmerge-logs unmerge-orphans userfetch userpriv usersandbox usersync xattr" FFLAGS="-march=native -O2 -pipe" GENTOO_MIRRORS="http://distfiles.gentoo.org" INSTALL_MASK="charset.alias /usr/share/locale/locale.alias" LANG="ru_RU.utf8" LDFLAGS="-Wl,-O1 -Wl,--as-needed" PKGDIR="/var/cache/binpkgs" PORTAGE_CONFIGROOT="/" PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --omit-dir-times --compress --force --whole-file --delete --stats --human-readable --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages --exclude=/.git" PORTAGE_TMPDIR="/var/tmp" SHELL="/bin/fish" USE="X acl amd64 bzip2 cli crypt dri fortran iconv ipv6 libglvnd libtirpc ncurses nls nptl openmp pam pcre pipewire pulseaudio readline seccomp split-usr ssl unicode wayland xattr zlib" ABI_X86="64" ADA_TARGET="gnat_2020" APACHE2_MODULES="authn_core authz_core socache_shmcb unixd actions alias auth_basic authn_alias authn_anon authn_dbm authn_default authn_file authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user autoindex cache cgi cgid dav dav_fs dav_lock deflate dir disk_cache env expires ext_filter file_cache filter headers include info log_config logio mem_cache mime mime_magic negotiation rewrite setenvif speling status unique_id userdir usertrack vhost_alias" CALLIGRA_FEATURES="karbon sheets words" COLLECTD_PLUGINS="df interface irq load memory rrdtool swap syslog" CPU_FLAGS_X86="mmx mmxext sse sse2" ELIBC="musl" GPSD_PROTOCOLS="ashtech aivdm earthmate evermore fv18 garmin garmintxt gpsclock greis isync itrax mtk3301 nmea ntrip navcom oceanserver oldstyle oncore rtcm104v2 rtcm104v3 sirf skytraq superstar2 timing tsip tripmate tnt ublox ubx" INPUT_DEVICES="libinput" KERNEL="linux" L10N="ru ru-RU fr fr-FR en en-US" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LIBREOFFICE_EXTENSIONS="presenter-console presenter-minimizer" LUA_SINGLE_TARGET="lua5-1" LUA_TARGETS="lua5-1" OFFICE_IMPLEMENTATION="libreoffice" PHP_TARGETS="php7-4 php8-0" POSTGRES_TARGETS="postgres12 postgres13" PYTHON_SINGLE_TARGET="python3_9" PYTHON_TARGETS="python3_9" RUBY_TARGETS="ruby26 ruby27" USERLAND="GNU" VIDEO_CARDS="amdgpu fbdev intel nouveau radeon radeonsi vesa dummy v4l" XTABLES_ADDONS="quota2 psd pknock lscan length2 ipv4options ipset ipp2p iface geoip fuzzy condition tee tarpit sysrq proto steal rawnat logmark ipmark dhcpmac delude chaos account" Unset: ADDR2LINE, AR, ARFLAGS, AS, ASFLAGS, CC, CCLD, CONFIG_SHELL, CPP, CPPFLAGS, CTARGET, CXX, CXXFILT, ELFEDIT, EMERGE_DEFAULT_OPTS, EXTRA_ECONF, F77FLAGS, FC, GCOV, GPROF, LC_ALL, LD, LEX, LFLAGS, LIBTOOL, LINGUAS, MAKE, MAKEFLAGS, MAKEOPTS, NM, OBJCOPY, OBJDUMP, PORTAGE_BINHOST, PORTAGE_BUNZIP2_COMMAND, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS, RANLIB, READELF, RUSTFLAGS, SIZE, STRINGS, STRIP, YACC, YFLAGS
Created attachment 764312 [details, diff] A rudimentary patch to include -DUNPREFIXED_SYMBOLS manually, since CFLAGS is overridden by the ebuild. Signed-off-by: Andrew Athalye
Created attachment 764319 [details, diff] Makefile patch: set CFLAGS only if unset
Created attachment 764322 [details] EBUILD: Specify CFLAGS before emake to prevent the Makefile's logic from being overridden The primary changes made were to invoke make as CFLAGS="${CFLAGS}" emake and to include the set-cflags-if-unset patch.
I've made an edited EBUILD and small Makefile patch to hopefully resolve the issue. In my testing it worked as expected and all necessary CFLAGS were passed to the compiler, leading to weak symbols being included. I've opened an issue upstream as well and submitted both this patch and one which simply concatenates the CFLAGS together.
Thanks for your work here. Please do link to upstream bugs here and vice versa though.
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=1d8718303b00e24d21ce70a6891a096e89c96f1d commit 1d8718303b00e24d21ce70a6891a096e89c96f1d Author: Sam James <sam@gentoo.org> AuthorDate: 2022-02-07 03:56:24 +0000 Commit: Sam James <sam@gentoo.org> CommitDate: 2022-02-07 04:00:57 +0000 sys-libs/libucontext: respect CFLAGS without overriding upstream define Fixes musl runtime as the right symbols get defined now (unprefixed). Bug: https://github.com/rui314/mold/issues/281 Bug: https://bugs.gentoo.org/832700 Closes: https://bugs.gentoo.org/832677 Thanks-to: Andrew Athalye <andrewathalye@outlook.com> Signed-off-by: Sam James <sam@gentoo.org> .../libucontext/files/libucontext-1.1-respect-CFLAGS.patch | 13 +++++++++++++ .../{libucontext-1.1.ebuild => libucontext-1.1-r1.ebuild} | 10 +++++++--- 2 files changed, 20 insertions(+), 3 deletions(-)
hey, I don't have a current usecase for libucontext, but with the patch there are still unresolved symbols in libucontext_posix.so.1: ldd /usr/lib/libucontext_posix.so.1 ldd (0x7fbbc5b000) libc.so => ldd (0x7fbbc5b000) Error relocating /usr/lib/libucontext_posix.so.1: libucontext_getcontext: symbol not found Error relocating /usr/lib/libucontext_posix.so.1: libucontext_swapcontext: symbol not found Error relocating /usr/lib/libucontext_posix.so.1: libucontext_setcontext: symbol not found for your information only
(In reply to tt_1 from comment #7) > hey, I don't have a current usecase for libucontext, but with the patch > there are still unresolved symbols in libucontext_posix.so.1: > > ldd /usr/lib/libucontext_posix.so.1 > ldd (0x7fbbc5b000) > libc.so => ldd (0x7fbbc5b000) > Error relocating /usr/lib/libucontext_posix.so.1: libucontext_getcontext: > symbol not found > Error relocating /usr/lib/libucontext_posix.so.1: libucontext_swapcontext: > symbol not found > Error relocating /usr/lib/libucontext_posix.so.1: libucontext_setcontext: > symbol not found > > > for your information only In an Alpine container: ``` / # ldd /lib/libucontext_posix.so.1 /lib/ld-musl-x86_64.so.1 (0x7f63920f2000) libc.musl-x86_64.so.1 => /lib/ld-musl-x86_64.so.1 (0x7f63920f2000) Error relocating /lib/libucontext_posix.so.1: libucontext_getcontext: symbol not found Error relocating /lib/libucontext_posix.so.1: libucontext_swapcontext: symbol not found Error relocating /lib/libucontext_posix.so.1: libucontext_setcontext: symbol not found ``` but libucontext.so is fine for me, so I think this is intended (to do with how the real POSIX symbols are just setcontext, etc, not prefixed).
