src/lib/libc/sys/interposing_table.c, branch release/13.1.0

libthr: wrap pdfork(2), same as fork(2).

2021-01-11T20:59:52Z

Without wrapping, rtld services and malloc(3) are not guaranteed to operate correctly in the forked child. Reviewed by: markj MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D28088

Fix initial exec TLS mode for dynamically loaded shared objects.

2019-03-29T17:52:57Z

If dso uses initial exec TLS mode, rtld tries to allocate TLS in static space. If there is no space left, the dlopen(3) fails. If space if allocated, initial content from PT_TLS segment is distributed to all threads' pcbs, which was missed and caused un-initialized TLS segment for such dso after dlopen(3). The mode is auto-detected either due to the relocation used, or if the DF_STATIC_TLS dynamic flag is set. In the later case, the TLS segment is tried to allocate earlier, which increases chance of the dlopen(3) to succeed. LLD was recently fixed to properly emit the flag, ld.bdf did it always. Initial test by: dumbbell Tested by: emaste (amd64), ian (arm) Tested by: Gerald Aryeetey (arm64) Sponsored by: The FreeBSD Foundation MFC after: 2 weeks Differential revision: https://reviews.freebsd.org/D19072

Add clock_nanosleep()

2017-03-19T00:51:12Z

Add a clock_nanosleep() syscall, as specified by POSIX. Make nanosleep() a wrapper around it. Attach the clock_nanosleep test from NetBSD. Adjust it for the FreeBSD behavior of updating rmtp only when interrupted by a signal. I believe this to be POSIX-compliant, since POSIX mentions the rmtp parameter only in the paragraph about EINTR. This is also what Linux does. (NetBSD updates rmtp unconditionally.) Copy the whole nanosleep.2 man page from NetBSD because it is complete and closely resembles the POSIX description. Edit, polish, and reword it a bit, being sure to keep any relevant text from the FreeBSD page. Reviewed by: kib, ngie, jilles MFC after: 3 weeks Relnotes: yes Sponsored by: Dell EMC Differential Revision: https://reviews.freebsd.org/D10020

The fdatasync(2) call must be cancellation point.

2016-08-16T08:27:03Z

Sponsored by: The FreeBSD Foundation MFC after: 13 days

If libthr.so is dlopened without RTLD_GLOBAL flag, the libthr symbols

2016-02-08T19:24:13Z

do not participate in the global symbols namespace, but rtld locks are still replaced and functions are interposed. In particular, __pthread_map_stacks_exec is resolved to the libc version. If a library is loaded later, which requires adjustment of the stack protection mode, rtld calls into libc __pthread_map_stacks_exec due to the symbols scope. The libc version might recurse into binder and recursively acquire rtld bind lock, causing the hang. Make libc __pthread_map_stacks_exec() interposed, which synchronizes rtld locks and version of the stack exec hook when libthr loaded, regardless of the symbol scope control or symbol resolution order. The __pthread_map_stacks_exec() symbol is removed from the private version in libthr since libc symbol now operates correctly in presence of libthr. Reported and tested by: markj Sponsored by: The FreeBSD Foundation MFC after: 2 weeks

The lseek(2), mmap(2), truncate(2), ftruncate(2), pread(2), and

2015-04-18T21:50:13Z

pwrite(2) syscalls are wrapped to provide compatibility with pre-7.x kernels which required padding before the off_t parameter. The fcntl(2) contains compatibility code to handle kernels before the struct flock was changed during the 8.x CURRENT development. The shims were reasonable to allow easier revert to the older kernel at that time. Now, two or three major releases later, shims do not serve any purpose. Such old kernels cannot handle current libc, so revert the compatibility code. Make padded syscalls support conditional under the COMPAT6 config option. For COMPAT32, the syscalls were under COMPAT6 already. Remove WITHOUT_SYSCALL_COMPAT build option, which only purpose was to (partially) disable the removed shims. Reviewed by: jhb, imp (previous versions) Discussed with: peter Sponsored by: The FreeBSD Foundation MFC after: 1 week

Make wait6(2), waitid(3) and ppoll(2) cancellation points. The

2015-04-18T21:35:41Z

waitid() function is required to be cancellable by the standard. The wait6() and ppoll() follow the other syscalls in their groups. Reviewed by: jhb, jilles (previous versions) Sponsored by: The FreeBSD Foundation MFC after: 1 week

Make kevent(2) a cancellation point.

2015-03-29T19:14:41Z

Note that to cancel blocked kevent(2) call, changelist must be empty, since we cannot cancel a call which already made changes to the process state. And in reverse, call which only makes changes to the kqueue state, without waiting for an event, is not cancellable. This makes a natural usage model to migrate kqueue loop to support cancellation, where existing single kevent(2) call must be split into two: first uncancellable update of kqueue, then cancellable wait for events. Note that this is ABI-incompatible change, but it is believed that there is no cancel-safe code that relies on kevent(2) not being a cancellation point. Option to preserve the ABI would be to keep kevent(2) as is, but add new call with flags to specify cancellation behaviour, which only value seems to add complications. Suggested and reviewed by: jilles Sponsored by: The FreeBSD Foundation MFC after: 2 weeks

Properly interpose libc spinlocks, was missed in r276630. In

2015-02-14T11:47:40Z

particular, stdio locking was affected. Reported and tested by: "Matthew D. Fuller" Sponsored by: The FreeBSD Foundation MFC after: 3 days

Reduce the size of the interposing table and amount of

2015-01-11T22:16:31Z

cancellation-handling code in the libthr. Translate some syscalls into their more generic counterpart, and remove translated syscalls from the table. List of the affected syscalls: creat, open -> openat raise -> thr_kill sleep, usleep -> nanosleep pause -> sigsuspend wait, wait3, waitpid -> wait4 Suggested and reviewed by: jilles (previous version) Sponsored by: The FreeBSD Foundation MFC after: 1 week