source: libcfa/src/exception.c @ 8108ba8

ADTast-experimentalpthread-emulationqualifiedEnum
Last change on this file since 8108ba8 was 8108ba8, checked in by Thierry Delisle <tdelisle@…>, 22 months ago

Started to add basic visibility control to libcfa

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File size: 21.7 KB
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1//
2// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
3//
4// The contents of this file are covered under the licence agreement in the
5// file "LICENCE" distributed with Cforall.
6//
7// exception.c --
8//
9// Author           : Andrew Beach
10// Created On       : Mon Jun 26 15:13:00 2017
11// Last Modified By : Andrew Beach
12// Last Modified On : Wed Feb 24 13:40:00 2021
13// Update Count     : 36
14//
15
16// Normally we would get this from the CFA prelude.
17#include <stddef.h> // for size_t
18
19#include <unwind.h> // for struct _Unwind_Exception {...};
20
21#include "exception.h"
22
23#include <stdlib.h>
24#include <stdio.h>
25#include <bits/debug.hfa>
26#include "concurrency/invoke.h"
27#include "stdhdr/assert.h"
28#include "virtual.h"
29
30#pragma GCC visibility push(default)
31
32#include "lsda.h"
33
34/* The exception class for our exceptions. Because of the vendor component
35 * its value would not be standard.
36 * Vendor: UWPL
37 * Language: CFA\0
38 */
39const _Unwind_Exception_Class __cfaehm_exception_class = 0x4c50575500414643;
40
41// Base Exception type id:
42struct __cfavir_type_info __cfatid_exception_t = {
43        NULL,
44};
45
46
47// Get the current exception context.
48// There can be a single global until multithreading occurs, then each stack
49// needs its own. We get this from libcfathreads (no weak attribute).
50__attribute__((weak)) struct exception_context_t * this_exception_context() {
51        static struct exception_context_t shared_stack = {NULL, NULL};
52        return &shared_stack;
53}
54
55
56// RESUMPTION ================================================================
57
58static void reset_top_resume(struct __cfaehm_try_resume_node ** store) {
59        this_exception_context()->top_resume = *store;
60}
61
62void __cfaehm_throw_resume(exception_t * except, void (*defaultHandler)(exception_t *)) {
63        struct exception_context_t * context = this_exception_context();
64
65        __cfadbg_print_safe(exception, "Throwing resumption exception\n");
66
67        {
68                __attribute__((cleanup(reset_top_resume)))
69                struct __cfaehm_try_resume_node * original_head = context->top_resume;
70                struct __cfaehm_try_resume_node * current = context->top_resume;
71
72                for ( ; current ; current = current->next) {
73                        context->top_resume = current->next;
74                        if (current->handler(except)) {
75                                return;
76                        }
77                }
78        } // End the search and return to the top of the stack.
79
80        // No handler found, fall back to the default operation.
81        __cfadbg_print_safe(exception, "Unhandled exception\n");
82        defaultHandler(except);
83}
84
85// Do we control where exceptions get thrown even with concurency?
86// If not these are not quite thread safe, the cleanup hook has to
87// be added after the node is built but before it is made the top node.
88
89void __cfaehm_try_resume_setup(struct __cfaehm_try_resume_node * node,
90                        _Bool (*handler)(exception_t * except)) {
91        struct exception_context_t * context = this_exception_context();
92        node->next = context->top_resume;
93        node->handler = handler;
94        context->top_resume = node;
95}
96
97void __cfaehm_try_resume_cleanup(struct __cfaehm_try_resume_node * node) {
98        struct exception_context_t * context = this_exception_context();
99        context->top_resume = node->next;
100}
101
102
103// MEMORY MANAGEMENT =========================================================
104
105#define NODE_TO_EXCEPT(node) ((exception_t *)(1 + (node)))
106#define EXCEPT_TO_NODE(except) ((struct __cfaehm_node *)(except) - 1)
107#define UNWIND_TO_NODE(unwind) ((struct __cfaehm_node *)(unwind))
108#define NULL_MAP(map, ptr) ((ptr) ? (map(ptr)) : NULL)
109
110// How to clean up an exception in various situations.
111static void __cfaehm_exception_cleanup(
112                _Unwind_Reason_Code reason,
113                struct _Unwind_Exception * exception) {
114        switch (reason) {
115        case _URC_FOREIGN_EXCEPTION_CAUGHT:
116                // This one we could clean-up to allow cross-language exceptions.
117        case _URC_FATAL_PHASE1_ERROR:
118        case _URC_FATAL_PHASE2_ERROR:
119        default:
120                abort();
121        }
122}
123
124// Creates a copy of the indicated exception and sets current_exception to it.
125static void __cfaehm_allocate_exception( exception_t * except ) {
126        struct exception_context_t * context = this_exception_context();
127
128        // Allocate memory for the exception.
129        struct __cfaehm_node * store = malloc(
130                sizeof( struct __cfaehm_node ) + except->virtual_table->size );
131
132        if ( ! store ) {
133                // Failure: cannot allocate exception. Terminate thread.
134                abort(); // <- Although I think it might be the process.
135        }
136
137        // Initialize the node:
138        exception_t * except_store = NODE_TO_EXCEPT(store);
139        store->unwind_exception.exception_class = __cfaehm_exception_class;
140        store->unwind_exception.exception_cleanup = __cfaehm_exception_cleanup;
141        store->handler_index = 0;
142        except->virtual_table->copy( except_store, except );
143
144        // Add the node to the list:
145        store->next = NULL_MAP(EXCEPT_TO_NODE, context->current_exception);
146        context->current_exception = except_store;
147}
148
149// Delete the provided exception, unsetting current_exception if relivant.
150static void __cfaehm_delete_exception( exception_t * except ) {
151        struct exception_context_t * context = this_exception_context();
152
153        __cfadbg_print_safe(exception, "Deleting Exception\n");
154
155        // Remove the exception from the list.
156        struct __cfaehm_node * to_free = EXCEPT_TO_NODE(except);
157        struct __cfaehm_node * node;
158
159        if ( context->current_exception == except ) {
160                node = to_free->next;
161                context->current_exception = NULL_MAP(NODE_TO_EXCEPT, node);
162        } else {
163                node = EXCEPT_TO_NODE(context->current_exception);
164                // It may always be in the first or second position.
165                while ( to_free != node->next ) {
166                        node = node->next;
167                }
168                node->next = to_free->next;
169        }
170
171        // Free the old exception node.
172        except->virtual_table->free( except );
173        free( to_free );
174}
175
176// CANCELLATION ==============================================================
177
178// Function needed by force unwind
179// It basically says to unwind the whole stack and then exit when we reach the end of the stack
180static _Unwind_Reason_Code _Stop_Fn(
181                int version,
182                _Unwind_Action actions,
183                _Unwind_Exception_Class exception_class,
184                struct _Unwind_Exception * unwind_exception,
185                struct _Unwind_Context * unwind_context,
186                void * stop_param) {
187        // Verify actions follow the rules we expect.
188        verify(actions & _UA_CLEANUP_PHASE);
189        verify(actions & _UA_FORCE_UNWIND);
190        verify(!(actions & _UA_SEARCH_PHASE));
191        verify(!(actions & _UA_HANDLER_FRAME));
192
193        if ( actions & _UA_END_OF_STACK ) {
194                abort();
195        } else {
196                return _URC_NO_REASON;
197        }
198}
199
200__attribute__((weak)) _Unwind_Reason_Code
201__cfaehm_cancellation_unwind( struct _Unwind_Exception * exception ) {
202        return _Unwind_ForcedUnwind( exception, _Stop_Fn, (void*)0x22 );
203}
204
205// Cancel the current stack, prefroming approprate clean-up and messaging.
206void __cfaehm_cancel_stack( exception_t * exception ) {
207        __cfaehm_allocate_exception( exception );
208
209        struct exception_context_t * context = this_exception_context();
210        struct __cfaehm_node * node = EXCEPT_TO_NODE(context->current_exception);
211
212        // Preform clean-up of any extra active exceptions.
213        while ( node->next ) {
214                struct __cfaehm_node * to_free = node->next;
215                node->next = to_free->next;
216                exception_t * except = NODE_TO_EXCEPT( to_free );
217                except->virtual_table->free( except );
218            free( to_free );
219        }
220
221        _Unwind_Reason_Code ret;
222        ret = __cfaehm_cancellation_unwind( &node->unwind_exception );
223        printf("UNWIND ERROR %d after force unwind\n", ret);
224        abort();
225}
226
227
228// TERMINATION ===============================================================
229
230// If this isn't a rethrow (*except==0), delete the provided exception.
231void __cfaehm_cleanup_terminate( void * except ) {
232        if ( *(void**)except ) __cfaehm_delete_exception( *(exception_t **)except );
233}
234
235static void __cfaehm_cleanup_default( exception_t ** except ) {
236        __cfaehm_delete_exception( *except );
237        *except = NULL;
238}
239
240// The exception that is being thrown must already be stored.
241static void __cfaehm_begin_unwind(void(*defaultHandler)(exception_t *)) {
242        struct exception_context_t * context = this_exception_context();
243        if ( NULL == context->current_exception ) {
244                printf("UNWIND ERROR missing exception in begin unwind\n");
245                abort();
246        }
247        struct _Unwind_Exception * storage =
248                &EXCEPT_TO_NODE(context->current_exception)->unwind_exception;
249
250        // Call stdlibc to raise the exception
251        __cfadbg_print_safe(exception, "Begin unwinding (storage &p, context %p)\n", storage, context);
252        _Unwind_Reason_Code ret = _Unwind_RaiseException( storage );
253
254        // If we reach here it means something happened. For resumption to work we need to find a way
255        // to return back to here. Most of them will probably boil down to setting a global flag and
256        // making the phase 1 either stop or fail. Causing an error on purpose may help avoiding
257        // unnecessary work but it might have some weird side effects. If we just pretend no handler
258        // was found that would work but may be expensive for no reason since we will always search
259        // the whole stack.
260
261#if defined( __x86_64 ) || defined( __i386 )
262        // We did not simply reach the end of the stack without finding a handler. This is an error.
263        if ( ret != _URC_END_OF_STACK ) {
264#else // defined( __ARM_ARCH )
265        // The return code from _Unwind_RaiseException seems to be corrupt on ARM at end of stack.
266        // This workaround tries to keep default exception handling working.
267        if ( ret == _URC_FATAL_PHASE1_ERROR || ret == _URC_FATAL_PHASE2_ERROR ) {
268#endif
269                printf("UNWIND ERROR %d after raise exception\n", ret);
270                abort();
271        }
272
273        // No handler found, go to the default operation.
274        __cfadbg_print_safe(exception, "Uncaught exception %p\n", storage);
275
276        __attribute__((cleanup(__cfaehm_cleanup_default)))
277        exception_t * exception = context->current_exception;
278        defaultHandler( exception );
279}
280
281void __cfaehm_throw_terminate( exception_t * val, void (*defaultHandler)(exception_t *) ) {
282        __cfadbg_print_safe(exception, "Throwing termination exception\n");
283
284        __cfaehm_allocate_exception( val );
285        __cfaehm_begin_unwind( defaultHandler );
286}
287
288static __attribute__((noreturn)) void __cfaehm_rethrow_adapter( exception_t * except ) {
289        // TODO: Print some error message.
290        (void)except;
291        abort();
292}
293
294void __cfaehm_rethrow_terminate(void) {
295        __cfadbg_print_safe(exception, "Rethrowing termination exception\n");
296
297        __cfaehm_begin_unwind( __cfaehm_rethrow_adapter );
298        abort();
299}
300
301#if defined( __x86_64 ) || defined( __i386 ) || defined( __ARM_ARCH )
302// This is our personality routine. For every stack frame annotated with
303// ".cfi_personality 0x3,__gcfa_personality_v0" this function will be called twice when unwinding.
304//  Once in the search phase and once in the cleanup phase.
305_Unwind_Reason_Code __gcfa_personality_v0(
306                int version,
307                _Unwind_Action actions,
308                unsigned long long exception_class,
309                struct _Unwind_Exception * unwind_exception,
310                struct _Unwind_Context * unwind_context)
311{
312
313        //__cfadbg_print_safe(exception, "CFA: 0x%lx\n", _Unwind_GetCFA(context));
314        __cfadbg_print_safe(exception, "Personality function (%d, %x, %llu, %p, %p):",
315                        version, actions, exception_class, unwind_exception, unwind_context);
316
317        // Verify that actions follow the rules we expect.
318        // This function should never be called at the end of the stack.
319        verify(!(actions & _UA_END_OF_STACK));
320        // Either only the search phase flag is set or...
321        if (actions & _UA_SEARCH_PHASE) {
322                verify(actions == _UA_SEARCH_PHASE);
323                __cfadbg_print_safe(exception, " lookup phase");
324        // ... we are in clean-up phase.
325        } else {
326                verify(actions & _UA_CLEANUP_PHASE);
327                __cfadbg_print_safe(exception, " cleanup phase");
328                // We shouldn't be the handler frame during forced unwind.
329                if (actions & _UA_HANDLER_FRAME) {
330                        verify(!(actions & _UA_FORCE_UNWIND));
331                        __cfadbg_print_safe(exception, " (handler frame)");
332                } else if (actions & _UA_FORCE_UNWIND) {
333                        __cfadbg_print_safe(exception, " (force unwind)");
334                }
335        }
336
337        // Get a pointer to the language specific data from which we will read what we need
338        const unsigned char * lsd = _Unwind_GetLanguageSpecificData( unwind_context );
339
340        if ( !lsd ) {   //Nothing to do, keep unwinding
341                printf(" no LSD");
342                goto UNWIND;
343        }
344
345        // Get the instuction pointer and a reading pointer into the exception table
346        lsda_header_info lsd_info;
347        const unsigned char * cur_ptr = parse_lsda_header(unwind_context, lsd, &lsd_info);
348        _Unwind_Ptr instruction_ptr = _Unwind_GetIP(unwind_context);
349
350        struct exception_context_t * context = this_exception_context();
351
352        // Linearly search the table for stuff to do
353        while ( cur_ptr < lsd_info.action_table ) {
354                _Unwind_Ptr callsite_start;
355                _Unwind_Ptr callsite_len;
356                _Unwind_Ptr callsite_landing_pad;
357                _uleb128_t  callsite_action;
358
359                // Decode the common stuff we have in here
360                cur_ptr = read_encoded_value(0, lsd_info.call_site_encoding, cur_ptr, &callsite_start);
361                cur_ptr = read_encoded_value(0, lsd_info.call_site_encoding, cur_ptr, &callsite_len);
362                cur_ptr = read_encoded_value(0, lsd_info.call_site_encoding, cur_ptr, &callsite_landing_pad);
363                cur_ptr = read_uleb128(cur_ptr, &callsite_action);
364
365                // Have we reach the correct frame info yet?
366                if ( lsd_info.Start + callsite_start + callsite_len < instruction_ptr ) {
367#ifdef __CFA_DEBUG_PRINT__
368                        void * ls = (void*)lsd_info.Start;
369                        void * cs = (void*)callsite_start;
370                        void * cl = (void*)callsite_len;
371                        void * bp = (void*)lsd_info.Start + callsite_start;
372                        void * ep = (void*)lsd_info.Start + callsite_start + callsite_len;
373                        void * ip = (void*)instruction_ptr;
374                        __cfadbg_print_safe(exception, "\nfound %p - %p (%p, %p, %p), looking for %p\n",
375                                        bp, ep, ls, cs, cl, ip);
376#endif // __CFA_DEBUG_PRINT__
377                        continue;
378                }
379
380                // Have we gone too far?
381                if ( lsd_info.Start + callsite_start > instruction_ptr ) {
382                        printf(" gone too far");
383                        break;
384                }
385
386                // Check for what we must do:
387                if ( 0 == callsite_landing_pad ) {
388                        // Nothing to do, move along
389                        __cfadbg_print_safe(exception, " no landing pad");
390                } else if (actions & _UA_SEARCH_PHASE) {
391                        // In search phase, these means we found a potential handler we must check.
392
393                        // We have arbitrarily decided that 0 means nothing to do and 1 means there is
394                        // a potential handler. This doesn't seem to conflict the gcc default behavior.
395                        if (callsite_action != 0) {
396                                // Now we want to run some code to see if the handler matches
397                                // This is the tricky part where we want to the power to run arbitrary code
398                                // However, generating a new exception table entry and try routine every time
399                                // is way more expansive than we might like
400                                // The information we have is :
401                                //  - The GR (Series of registers)
402                                //    GR1=GP Global Pointer of frame ref by context
403                                //  - The instruction pointer
404                                //  - The instruction pointer info (???)
405                                //  - The CFA (Canonical Frame Address)
406                                //  - The BSP (Probably the base stack pointer)
407
408                                // The current apprach uses one exception table entry per try block
409                                _uleb128_t imatcher;
410                                // Get the relative offset to the {...}?
411                                cur_ptr = read_uleb128(cur_ptr, &imatcher);
412
413                                _Unwind_Word match_pos =
414#                               if defined( __x86_64 )
415                                    _Unwind_GetCFA(unwind_context) + 8;
416#                               elif defined( __i386 )
417                                    _Unwind_GetCFA(unwind_context) + 24;
418#                               elif defined( __ARM_ARCH )
419                                    _Unwind_GetCFA(unwind_context) + 40;
420#                               endif
421                                int (*matcher)(exception_t *) = *(int(**)(exception_t *))match_pos;
422
423                                int index = matcher(context->current_exception);
424                                _Unwind_Reason_Code ret = (0 == index)
425                                        ? _URC_CONTINUE_UNWIND : _URC_HANDLER_FOUND;
426                                UNWIND_TO_NODE(unwind_exception)->handler_index = index;
427
428                                // Based on the return value, check if we matched the exception
429                                if (ret == _URC_HANDLER_FOUND) {
430                                        __cfadbg_print_safe(exception, " handler found\n");
431                                } else {
432                                        // TODO: Continue the search if there is more in the table.
433                                        __cfadbg_print_safe(exception, " no handler\n");
434                                }
435                                return ret;
436                        }
437
438                        // This is only a cleanup handler, ignore it
439                        __cfadbg_print_safe(exception, " no action");
440                } else {
441                        // In clean-up phase, no destructors here but this could be the handler.
442
443                        if ( (callsite_action != 0) && !(actions & _UA_HANDLER_FRAME) ){
444                                // If this is a potential exception handler
445                                // but not the one that matched the exception in the seach phase,
446                                // just ignore it
447                                goto UNWIND;
448                        }
449
450                        // We need to run some clean-up or a handler
451                        // These statment do the right thing but I don't know any specifics at all
452                        _Unwind_SetGR( unwind_context, __builtin_eh_return_data_regno(0),
453                                (_Unwind_Ptr)unwind_exception );
454                        _Unwind_SetGR( unwind_context, __builtin_eh_return_data_regno(1), 0 );
455
456                        // I assume this sets the instruction pointer to the adress of the landing pad
457                        // It doesn't actually set it, it only state the value that needs to be set once we
458                        // return _URC_INSTALL_CONTEXT
459                        _Unwind_SetIP( unwind_context, ((lsd_info.LPStart) + (callsite_landing_pad)) );
460
461                        __cfadbg_print_safe(exception, " action\n");
462
463                        // Return have some action to run
464                        return _URC_INSTALL_CONTEXT;
465                }
466        }
467        // No handling found
468        __cfadbg_print_safe(exception, " table end reached");
469
470        UNWIND:
471        __cfadbg_print_safe(exception, " unwind\n");
472
473        // Keep unwinding the stack
474        return _URC_CONTINUE_UNWIND;
475}
476
477#pragma GCC push_options
478#pragma GCC optimize(0)
479
480// Try statements are hoisted out see comments for details. While this could probably be unique
481// and simply linked from libcfa but there is one problem left, see the exception table for details
482__attribute__((noinline))
483void __cfaehm_try_terminate(void (*try_block)(),
484                void (*catch_block)(int index, exception_t * except),
485                __attribute__((unused)) int (*match_block)(exception_t * except)) {
486        //! volatile int xy = 0;
487        //! printf("%p %p %p %p\n", &try_block, &catch_block, &match_block, &xy);
488
489        // Setup the personality routine and exception table.
490        // Unforturnately these clobber gcc cancellation support which means we can't get access to
491        // the attribute cleanup tables at the same time. We would have to inspect the assembly to
492        // create a new set ourselves.
493#ifdef __PIC__
494        asm volatile (".cfi_personality 0x9b,CFA.ref.__gcfa_personality_v0");
495        asm volatile (".cfi_lsda 0x1b, .LLSDACFA2");
496#else
497        asm volatile (".cfi_personality 0x3,__gcfa_personality_v0");
498        asm volatile (".cfi_lsda 0x3, .LLSDACFA2");
499#endif
500
501        // Label which defines the start of the area for which the handler is setup.
502        asm volatile (".TRYSTART:");
503
504        // The actual statements of the try blocks
505        try_block();
506
507        // asm statement to prevent deadcode removal
508        asm volatile goto ("" : : : : CATCH );
509
510        // Normal return for when there is no throw.
511        return;
512
513        // Exceptionnal path
514        CATCH : __attribute__(( unused ));
515        // Label which defines the end of the area for which the handler is setup.
516        asm volatile (".TRYEND:");
517        // Label which defines the start of the exception landing pad. Basically what is called when
518        // the exception is caught. Note, if multiple handlers are given, the multiplexing should be
519        // done by the generated code, not the exception runtime.
520        asm volatile (".CATCH:");
521
522        // Exception handler
523        // Note: Saving the exception context on the stack breaks termination exceptions.
524        catch_block( EXCEPT_TO_NODE( this_exception_context()->current_exception )->handler_index,
525                     this_exception_context()->current_exception );
526}
527
528// Exception table data we need to generate. While this is almost generic, the custom data refers
529// to {*}try_terminate, which is no way generic. Some more works need to be done if we want to
530// have a single call to the try routine.
531
532#ifdef __PIC__
533asm (
534        // HEADER
535        ".LFECFA1:\n"
536#if defined( __x86_64 ) || defined( __i386 )
537        "       .globl  __gcfa_personality_v0\n"
538#else // defined( __ARM_ARCH )
539        "       .global __gcfa_personality_v0\n"
540#endif
541        "       .section        .gcc_except_table,\"a\",@progbits\n"
542        // TABLE HEADER (important field is the BODY length at the end)
543        ".LLSDACFA2:\n"
544        "       .byte   0xff\n"
545        "       .byte   0xff\n"
546        "       .byte   0x1\n"
547        "       .uleb128 .LLSDACSECFA2-.LLSDACSBCFA2\n"
548        // BODY (language specific data)
549        // This uses language specific data and can be modified arbitrarily
550        // We use handled area offset, handled area length,
551        // handler landing pad offset and 1 (action code, gcc seems to use 0).
552        ".LLSDACSBCFA2:\n"
553        "       .uleb128 .TRYSTART-__cfaehm_try_terminate\n"
554        "       .uleb128 .TRYEND-.TRYSTART\n"
555        "       .uleb128 .CATCH-__cfaehm_try_terminate\n"
556        "       .uleb128 1\n"
557        ".LLSDACSECFA2:\n"
558        // TABLE FOOTER
559        "       .text\n"
560        "       .size   __cfaehm_try_terminate, .-__cfaehm_try_terminate\n"
561);
562
563// Somehow this piece of helps with the resolution of debug symbols.
564__attribute__((unused)) static const int dummy = 0;
565
566asm (
567        // Add a hidden symbol which points at the function.
568        "       .hidden CFA.ref.__gcfa_personality_v0\n"
569        "       .weak   CFA.ref.__gcfa_personality_v0\n"
570        // No clue what this does specifically
571        "       .section        .data.rel.local.CFA.ref.__gcfa_personality_v0,\"awG\",@progbits,CFA.ref.__gcfa_personality_v0,comdat\n"
572#if defined( __x86_64 ) || defined( __i386 )
573        "       .align 8\n"
574#else // defined( __ARM_ARCH )
575        "       .align 3\n"
576#endif
577        "       .type CFA.ref.__gcfa_personality_v0, @object\n"
578        "       .size CFA.ref.__gcfa_personality_v0, 8\n"
579        "CFA.ref.__gcfa_personality_v0:\n"
580#if defined( __x86_64 )
581        "       .quad __gcfa_personality_v0\n"
582#elif defined( __i386 )
583        "       .long __gcfa_personality_v0\n"
584#else // defined( __ARM_ARCH )
585        "       .xword __gcfa_personality_v0\n"
586#endif
587);
588#else // __PIC__
589asm (
590        // HEADER
591        ".LFECFA1:\n"
592#if defined( __x86_64 ) || defined( __i386 )
593        "       .globl  __gcfa_personality_v0\n"
594#else // defined( __ARM_ARCH )
595        "       .global __gcfa_personality_v0\n"
596#endif
597        "       .section        .gcc_except_table,\"a\",@progbits\n"
598        // TABLE HEADER (important field is the BODY length at the end)
599        ".LLSDACFA2:\n"
600        "       .byte   0xff\n"
601        "       .byte   0xff\n"
602        "       .byte   0x1\n"
603        "       .uleb128 .LLSDACSECFA2-.LLSDACSBCFA2\n"
604        // BODY (language specific data)
605        ".LLSDACSBCFA2:\n"
606        //      Handled area start (relative to start of function)
607        "       .uleb128 .TRYSTART-__cfaehm_try_terminate\n"
608        //      Handled area length
609        "       .uleb128 .TRYEND-.TRYSTART\n"
610        //      Handler landing pad address (relative to start of function)
611        "       .uleb128 .CATCH-__cfaehm_try_terminate\n"
612        //      Action code, gcc seems to always use 0.
613        "       .uleb128 1\n"
614        // TABLE FOOTER
615        ".LLSDACSECFA2:\n"
616        "       .text\n"
617        "       .size   __cfaehm_try_terminate, .-__cfaehm_try_terminate\n"
618        "       .ident  \"GCC: (Ubuntu 6.2.0-3ubuntu11~16.04) 6.2.0 20160901\"\n"
619        "       .section        .note.GNU-stack,\"x\",@progbits\n"
620);
621#endif // __PIC__
622
623#pragma GCC pop_options
624
625#else
626        #error unsupported hardware architecture
627#endif // __x86_64 || __i386 || __ARM_ARCH
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