src/libexec/rtld-elf/rtld_lock.c, branch releng/10.2

MFC r280816:

2015-04-12T06:45:40Z

Change default visibility for rtld to hidden, on x86.

MFC r266609:

2014-06-07T02:45:24Z

Change the _rtld_atfork() to lock the bind lock in write mode.

Rtld links with the specially built pic static libc library to get some

2011-08-24T20:05:13Z

C runtime services, like printf(). Unfortunately, the multithread-safeness measures in the libc do not work in rtld environment. Rip the kernel printf() implementation and use it in the rtld instead of libc version. This printf does not require any shared global data and thus is mt-safe. Systematically use rtld_printf() and related functions, remove the calls to err(3). Note that stdio is still pulled from libc due to libmap implementaion using fopen(). This is safe but unoptimal, and can be changed later. Reported and tested by: pgj Diagnosed and reviewed by: kan (previous version) Approved by: re (bz)

Use sigsetjmp/siglongjmp with disabled signal mask access for

2011-02-09T09:20:27Z

lock upgrade in rtld. There is no need to care about the mask, which causes a lot of unneeded sigprocmask(2) calls during each symbol lookup.

Implement support for ELF filters in rtld. Both normal and auxillary

2010-12-25T08:51:20Z

filters are implemented. Filtees are loaded on demand, unless LD_LOADFLTR environment variable is set or -z loadfltr was specified during the linking. This forces rtld to upgrade read-locked rtld_bind_lock to write lock when it encounters an object with filter during symbol lookup. Consolidate common arguments of the symbol lookup functions in the SymLook structure. Track the state of the rtld locks in the RtldLockState structure. Pass local RtldLockState through the rtld symbol lookup calls to allow lock upgrades. Reviewed by: kan Tested by: Mykola Dzham , nwhitehorn (powerpc)

Prefer to for the definition of

2009-04-20T10:35:50Z
CACHE_LINE_SIZE. Submitted by: bde MFC after: 2 weeks

Explicitly include machine/param.h for CACHE_LINE_SIZE.

2009-04-19T23:03:57Z
MFC after: 2 weeks

Add two rtld exported symbols, _rtld_atfork_pre and _rtld_atfork_post.

2008-11-27T11:27:59Z
Threading library calls _pre before the fork, allowing the rtld to lock itself to ensure that other threads of the process are out of dynamic linker. _post releases the locks. This allows the rtld to have consistent state in the child. Although child may legitimately call only async-safe functions, the call may need plt relocation resolution, and this requires working rtld. Reported and debugging help by: rink Reviewed by: kan, davidxu MFC after: 1 month (anyway, not before 7.1 is out)

Allow multiple locks to be acquired by detecting corresponding

2008-09-16T01:46:11Z
bit flag, otherwise if a thread acquired a lock, another thread or the current thread itself can no longer acquire another lock because thread_mask_set() return whole flag word, this results bit leaking in the word and misbehavior in later locking and unlocking.

Fix the problem with the C++ exception handling for the multithreaded

2008-05-06T09:27:41Z
programs. From the PR description: The gcc runtime's _Unwind_Find_FDE function, invoked during exception handling's stack unwinding, is not safe to execute from within multiple threads. FreeBSD' s dl_iterate_phdr() however permits multiple threads to pass through it though. The result is surprisingly reliable infinite looping of one or more threads if they just happen to be unwinding at the same time. Introduce the new lock that is write locked around the dl_iterate_pdr, thus providing required exclusion for the stack unwinders. PR: threads/123062 Submitted by: Andy Newman Reviewed by: kan MFC after: 2 weeks