source: libcfa/src/exception.c

Last change on this file was ed395761, checked in by Henry Xue <y58xue@…>, 6 months ago

Workaround to get default exception handling on ARM working

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