That's probably worth a shot. Static linking will work anyway because libc.a in effect embeds libsys to retain compatability.
-- Brooks On Wed, Feb 21, 2024 at 09:12:41PM +0100, Dimitry Andric wrote: > Can't we just add libsys.so to the /usr/lib/libc.so linker script? That would > work for everything except static linking? > > -Dimitry > > > On 21 Feb 2024, at 21:00, Brooks Davis <bro...@freebsd.org> wrote: > > > > TL;DR: you can work around this by adding -lsys to the link line and I > > aim to improve the situation soon. > > > > The sanitizers reach somewhat questionably into libc internals that are > > exported to allow rtld to update them. I was unable to find an solution > > that didn't break this and I felt that fixing things like closefrom() > > using non-deprecated syscalls was more important than avoiding changes > > to the sanitizer interface. > > > > I'm trying to find a way to better solution to the sanitizer. A few > > ideas I'm considering: > > - Teach clang to add -lsys when linking with sanitizers on sufficently > > new systems (con: doesn't fix gcc). > > - Make the symbol weak in the sanitizer and complain when it's not > > found or call back to using environ. The latter migth have > > limitations around direct exec with rtld. > > - Relocate __elf_aux_vector to csu so the symbol is always available. > > - Adding a new interface to access __elf_aux_vector directly. > > > > I'll continue to work on this. > > > > -- Brooks > > > > On Wed, Feb 21, 2024 at 09:52:23AM +0000, hartmut.bra...@dlr.de wrote: > >> Hi, > >> > >> I updated yesterday and now event a minimal program with > >> > >> cc -fsanitize=address > >> > >> produces > >> > >> ld: error: undefined symbol: __elf_aux_vector > >>>>> referenced by sanitizer_linux_libcdep.cpp:950 > >>>>> (/usr/src/contrib/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp:950) > >>>>> sanitizer_linux_libcdep.o:(__sanitizer::ReExec()) in > >>>>> archive /usr/lib/clang/17/lib/freebsd/libclang_rt.asan-x86_64.a > >> cc: error: linker command failed with exit code 1 (use -v to see > >> invocation) > >> > >> I think this is caused by the libsys split. > >> > >> Cheers, > >> Harti > >> > >> -----Original Message----- > >> From: owner-freebsd-curr...@freebsd.org > >> <owner-freebsd-curr...@freebsd.org> On Behalf Of Brooks Davis > >> Sent: Friday, February 2, 2024 11:32 PM > >> To: curr...@freebsd.org > >> Subject: libc/libsys split coming soon > >> > >> TL;DR: The implementation of system calls is moving to a seperate library > >> (libsys). No changes are required to existing software (except to ensure > >> that libsys is present when building custom disk images). > >> > >> Code: https://github.com/freebsd/freebsd-src/pull/908 > >> > >> After nearly a decade of intermittent work, I'm about to land a series of > >> patches which moves system calls, vdso support, and libc's parsing of the > >> ELF auxiliary argument vector into a separate library (libsys). I plan to > >> do this early next week (February 5th). > >> > >> This change serves three primary purposes: > >> 1. It's easier to completely replace system call implementations for > >> tracing or compartmentalization purposes. > >> 2. It simplifies the implementation of restrictions on system calls such > >> as those implemented by OpenBSD's msyscall(2) > >> (https://man.openbsd.org/msyscall.2). > >> 3. It allows language runtimes to link with libsys for system call > >> implementations without requiring libc. > >> > >> libsys is an auxiliary filter for libc. This means that for any symbol > >> defined by both, the libsys version takes precedence at runtime. For > >> system call implementations, libc contains empty stubs. For others it > >> contains copies of the functions (this could be further refined at a later > >> date). The statically linked libc contains the full implementations so > >> linking libsys is not required. > >> > >> Additionally, libthr is now linked with libsys to provide _umtx_op_err(). > >> > >> The overall implementation follows https://reviews.freebsd.org/D14609, > >> but is redone from scratch as multiple commits to facilitate review and > >> assist git's rename detection. > >> > >> Testing: > >> - Boot testing on amd64, aarch64, and riscv > >> - make tinderbox (prior version, final run in progress) > >> - exp-run: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=276391 > >> - Kyua tests in poudriere amd64 jails: same 359 failures as with the > >> latest freebsdci build > >> > >> Thanks to Ali Mashtizadeh and Tal Garfinkel for D14609 and many apologies > >> for not landing this in a timely manner. Additional thanks to kib@ for > >> many rounds of review, markj@ and kib@ for debugging rtld issues exposed > >> by this patch, and antoine@ for exp-runs. > >> > >> Future work: > >> - Purely functional interfaces to system calls (no errorno). > >> Unfortunately there isn't an obvious way to do this without > >> significant (possibly generated) assembly code. > >> - Investigate msyscall(2) and pinsyscalls(2). > >> - Reduce the size of stubs in libc. I????????ve errored on the > >> side of not touching the copies that end up in libc to keep diff > >> size down. We might want to generate empty stubs instead. > >> > >> See also: > >> - Solaris Linker and Libraries Guide: > >> https://docs.oracle.com/cd/E23824_01/html/819-0690/chapter4-4.html > >> > >> -- Brooks > >
