Fix the problem with the C++ exception handling for the multithreaded
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 <an at atrn org> Reviewed by: kan MFC after: 2 weeks
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=178807
@ -2129,9 +2129,10 @@ dl_iterate_phdr(__dl_iterate_hdr_callback callback, void *param)
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{
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struct dl_phdr_info phdr_info;
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const Obj_Entry *obj;
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int error, lockstate;
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int error, bind_lockstate, phdr_lockstate;
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lockstate = rlock_acquire(rtld_bind_lock);
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phdr_lockstate = wlock_acquire(rtld_phdr_lock);
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bind_lockstate = rlock_acquire(rtld_bind_lock);
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error = 0;
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@ -2150,7 +2151,8 @@ dl_iterate_phdr(__dl_iterate_hdr_callback callback, void *param)
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break;
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}
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rlock_release(rtld_bind_lock, lockstate);
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rlock_release(rtld_bind_lock, bind_lockstate);
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wlock_release(rtld_phdr_lock, phdr_lockstate);
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return (error);
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}
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@ -171,7 +171,7 @@ thread_mask_clear(int mask)
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lockinfo.thread_clr_flag(mask);
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}
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#define RTLD_LOCK_CNT 2
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#define RTLD_LOCK_CNT 3
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struct rtld_lock {
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void *handle;
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int mask;
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@ -179,6 +179,7 @@ struct rtld_lock {
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rtld_lock_t rtld_bind_lock = &rtld_locks[0];
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rtld_lock_t rtld_libc_lock = &rtld_locks[1];
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rtld_lock_t rtld_phdr_lock = &rtld_locks[2];
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int
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rlock_acquire(rtld_lock_t lock)
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@ -52,6 +52,7 @@ typedef struct rtld_lock *rtld_lock_t;
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extern rtld_lock_t rtld_bind_lock;
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extern rtld_lock_t rtld_libc_lock;
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extern rtld_lock_t rtld_phdr_lock;
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int rlock_acquire(rtld_lock_t);
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int wlock_acquire(rtld_lock_t);
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