| 1 | /* _longjmp_unwind -- Clean up stack frames unwound by longjmp. Hurd version. |
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| 2 | Copyright (C) 1995-2022 Free Software Foundation, Inc. |
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| 3 | This file is part of the GNU C Library. |
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| 4 | |
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| 5 | The GNU C Library is free software; you can redistribute it and/or |
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| 6 | modify it under the terms of the GNU Lesser General Public |
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| 7 | License as published by the Free Software Foundation; either |
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| 8 | version 2.1 of the License, or (at your option) any later version. |
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| 9 | |
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| 10 | The GNU C Library is distributed in the hope that it will be useful, |
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 13 | Lesser General Public License for more details. |
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| 14 | |
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| 15 | You should have received a copy of the GNU Lesser General Public |
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| 16 | License along with the GNU C Library; if not, see |
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| 17 | <https://www.gnu.org/licenses/>. */ |
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| 18 | |
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| 19 | #include <jmpbuf-unwind.h> |
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| 20 | #include <hurd/userlink.h> |
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| 21 | #include <hurd/signal.h> |
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| 22 | #include <hurd/sigpreempt.h> |
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| 23 | #include <assert.h> |
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| 24 | #include <stdint.h> |
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| 25 | |
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| 26 | |
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| 27 | #ifndef _JMPBUF_UNWINDS |
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| 28 | #error "<jmpbuf-unwind.h> fails to define _JMPBUF_UNWINDS" |
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| 29 | #endif |
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| 30 | |
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| 31 | static inline uintptr_t |
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| 32 | demangle_ptr (uintptr_t x) |
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| 33 | { |
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| 34 | # ifdef PTR_DEMANGLE |
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| 35 | PTR_DEMANGLE (x); |
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| 36 | # endif |
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| 37 | return x; |
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| 38 | } |
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| 39 | |
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| 40 | /* This function is called by `longjmp' (with its arguments) to restore |
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| 41 | active resources to a sane state before the frames code using them are |
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| 42 | jumped out of. */ |
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| 43 | |
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| 44 | void |
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| 45 | _longjmp_unwind (jmp_buf env, int val) |
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| 46 | { |
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| 47 | struct hurd_sigstate *ss = _hurd_self_sigstate (); |
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| 48 | struct hurd_userlink *link; |
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| 49 | |
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| 50 | /* All access to SS->active_resources must take place inside a critical |
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| 51 | section where signal handlers cannot run. */ |
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| 52 | __spin_lock (&ss->lock); |
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| 53 | assert (! __spin_lock_locked (&ss->critical_section_lock)); |
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| 54 | __spin_lock (&ss->critical_section_lock); |
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| 55 | |
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| 56 | /* Remove local signal preemptors being unwound past. */ |
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| 57 | while (ss->preemptors |
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| 58 | && _JMPBUF_UNWINDS (env[0].__jmpbuf, ss->preemptors, demangle_ptr)) |
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| 59 | ss->preemptors = ss->preemptors->next; |
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| 60 | |
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| 61 | __spin_unlock (&ss->lock); |
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| 62 | |
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| 63 | /* Iterate over the current thread's list of active resources. |
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| 64 | Process the head portion of the list whose links reside |
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| 65 | in stack frames being unwound by this jump. */ |
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| 66 | |
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| 67 | for (link = ss->active_resources; |
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| 68 | link && _JMPBUF_UNWINDS (env[0].__jmpbuf, link, demangle_ptr); |
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| 69 | link = link->thread.next) |
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| 70 | /* Remove this link from the resource's users list, |
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| 71 | since the frame using the resource is being unwound. |
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| 72 | This call returns nonzero if that was the last user. */ |
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| 73 | if (_hurd_userlink_unlink (link)) |
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| 74 | /* One of the frames being unwound by the longjmp was the last user |
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| 75 | of its resource. Call the cleanup function to deallocate it. */ |
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| 76 | (*link->cleanup) (link->cleanup_data, env, val); |
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| 77 | |
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| 78 | _hurd_critical_section_unlock (ss); |
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| 79 | } |
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| 80 | |
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