source: libcfa/src/exception.c @ 915aa11

arm-ehjacob/cs343-translationnew-ast-unique-expr
Last change on this file since 915aa11 was 915aa11, checked in by Peter A. Buhr <pabuhr@…>, 15 months ago

start ARM stubs for exception handling

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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 : Peter A. Buhr
12// Last Modified On : Sat Aug 29 15:52:22 2020
13// Update Count     : 34
14//
15
16// Normally we would get this from the CFA prelude.
17#include <stddef.h> // for size_t
18
19#include "exception.h"
20
21#include <stdlib.h>
22#include <stdio.h>
23#include <unwind.h>
24#include <bits/debug.hfa>
25#include "concurrency/invoke.h"
26#include "stdhdr/assert.h"
27
28#if defined( __ARM_ARCH )
29#warning FIX ME: temporary hack to keep ARM build working
30#ifndef _URC_FATAL_PHASE1_ERROR
31#define _URC_FATAL_PHASE1_ERROR 3
32#endif // ! _URC_FATAL_PHASE1_ERROR
33#ifndef _URC_FATAL_PHASE2_ERROR
34#define _URC_FATAL_PHASE2_ERROR 2
35#endif // ! _URC_FATAL_PHASE2_ERROR
36#endif // __ARM_ARCH
37
38#include "lsda.h"
39
40/* The exception class for our exceptions. Because of the vendor component
41 * its value would not be standard.
42 * Vendor: UWPL
43 * Language: CFA\0
44 */
45const _Unwind_Exception_Class __cfaehm_exception_class = 0x4c50575500414643;
46
47// Base exception vtable is abstract, you should not have base exceptions.
48struct __cfaehm_base_exception_t_vtable
49                ___cfaehm_base_exception_t_vtable_instance = {
50        .parent = NULL,
51        .size = 0,
52        .copy = NULL,
53        .free = NULL,
54        .msg = NULL
55};
56
57
58// Get the current exception context.
59// There can be a single global until multithreading occurs, then each stack
60// needs its own. We get this from libcfathreads (no weak attribute).
61__attribute__((weak)) struct exception_context_t * this_exception_context() {
62        static struct exception_context_t shared_stack = {NULL, NULL};
63        return &shared_stack;
64}
65
66
67// RESUMPTION ================================================================
68
69static void reset_top_resume(struct __cfaehm_try_resume_node ** store) {
70        this_exception_context()->top_resume = *store;
71}
72
73void __cfaehm_throw_resume(exception_t * except, void (*defaultHandler)(exception_t *)) {
74        struct exception_context_t * context = this_exception_context();
75
76        __cfadbg_print_safe(exception, "Throwing resumption exception\n");
77
78        {
79                __attribute__((cleanup(reset_top_resume)))
80                struct __cfaehm_try_resume_node * original_head = context->top_resume;
81                struct __cfaehm_try_resume_node * current = context->top_resume;
82
83                for ( ; current ; current = current->next) {
84                        context->top_resume = current->next;
85                        if (current->handler(except)) {
86                                return;
87                        }
88                }
89        } // End the search and return to the top of the stack.
90
91        // No handler found, fall back to the default operation.
92        __cfadbg_print_safe(exception, "Unhandled exception\n");
93        defaultHandler(except);
94}
95
96// Do we control where exceptions get thrown even with concurency?
97// If not these are not quite thread safe, the cleanup hook has to
98// be added after the node is built but before it is made the top node.
99
100void __cfaehm_try_resume_setup(struct __cfaehm_try_resume_node * node,
101                        _Bool (*handler)(exception_t * except)) {
102        struct exception_context_t * context = this_exception_context();
103        node->next = context->top_resume;
104        node->handler = handler;
105        context->top_resume = node;
106}
107
108void __cfaehm_try_resume_cleanup(struct __cfaehm_try_resume_node * node) {
109        struct exception_context_t * context = this_exception_context();
110        context->top_resume = node->next;
111}
112
113
114// MEMORY MANAGEMENT =========================================================
115
116struct __cfaehm_node {
117        struct _Unwind_Exception unwind_exception;
118        struct __cfaehm_node * next;
119        int handler_index;
120};
121
122#define NODE_TO_EXCEPT(node) ((exception_t *)(1 + (node)))
123#define EXCEPT_TO_NODE(except) ((struct __cfaehm_node *)(except) - 1)
124#define UNWIND_TO_NODE(unwind) ((struct __cfaehm_node *)(unwind))
125#define NULL_MAP(map, ptr) ((ptr) ? (map(ptr)) : NULL)
126
127// How to clean up an exception in various situations.
128static void __cfaehm_exception_cleanup(
129                _Unwind_Reason_Code reason,
130                struct _Unwind_Exception * exception) {
131        switch (reason) {
132        case _URC_FOREIGN_EXCEPTION_CAUGHT:
133                // This one we could clean-up to allow cross-language exceptions.
134        case _URC_FATAL_PHASE1_ERROR:
135        case _URC_FATAL_PHASE2_ERROR:
136        default:
137                abort();
138        }
139}
140
141// Creates a copy of the indicated exception and sets current_exception to it.
142static void __cfaehm_allocate_exception( exception_t * except ) {
143        struct exception_context_t * context = this_exception_context();
144
145        // Allocate memory for the exception.
146        struct __cfaehm_node * store = malloc(
147                sizeof( struct __cfaehm_node ) + except->virtual_table->size );
148
149        if ( ! store ) {
150                // Failure: cannot allocate exception. Terminate thread.
151                abort(); // <- Although I think it might be the process.
152        }
153
154        // Initialize the node:
155        exception_t * except_store = NODE_TO_EXCEPT(store);
156        store->unwind_exception.exception_class = __cfaehm_exception_class;
157        store->unwind_exception.exception_cleanup = __cfaehm_exception_cleanup;
158        store->handler_index = 0;
159        except->virtual_table->copy( except_store, except );
160
161        // Add the node to the list:
162        store->next = NULL_MAP(EXCEPT_TO_NODE, context->current_exception);
163        context->current_exception = except_store;
164}
165
166// Delete the provided exception, unsetting current_exception if relivant.
167static void __cfaehm_delete_exception( exception_t * except ) {
168        struct exception_context_t * context = this_exception_context();
169
170        __cfadbg_print_safe(exception, "Deleting Exception\n");
171
172        // Remove the exception from the list.
173        struct __cfaehm_node * to_free = EXCEPT_TO_NODE(except);
174        struct __cfaehm_node * node;
175
176        if ( context->current_exception == except ) {
177                node = to_free->next;
178                context->current_exception = NULL_MAP(NODE_TO_EXCEPT, node);
179        } else {
180                node = EXCEPT_TO_NODE(context->current_exception);
181                // It may always be in the first or second position.
182                while ( to_free != node->next ) {
183                        node = node->next;
184                }
185                node->next = to_free->next;
186        }
187
188        // Free the old exception node.
189        except->virtual_table->free( except );
190        free( to_free );
191}
192
193// CANCELLATION ==============================================================
194
195// Function needed by force unwind
196// It basically says to unwind the whole stack and then exit when we reach the end of the stack
197static _Unwind_Reason_Code _Stop_Fn(
198                int version,
199                _Unwind_Action actions,
200                _Unwind_Exception_Class exception_class,
201                struct _Unwind_Exception * unwind_exception,
202                struct _Unwind_Context * unwind_context,
203                void * stop_param) {
204        // Verify actions follow the rules we expect.
205        verify(actions & _UA_CLEANUP_PHASE);
206        verify(actions & _UA_FORCE_UNWIND);
207        verify(!(actions & _UA_SEARCH_PHASE));
208        verify(!(actions & _UA_HANDLER_FRAME));
209
210        if ( actions & _UA_END_OF_STACK ) {
211                abort();
212        } else {
213                return _URC_NO_REASON;
214        }
215}
216
217__attribute__((weak)) _Unwind_Reason_Code
218__cfaehm_cancellation_unwind( struct _Unwind_Exception * exception ) {
219        return _Unwind_ForcedUnwind( exception, _Stop_Fn, (void*)0x22 );
220}
221
222// Cancel the current stack, prefroming approprate clean-up and messaging.
223void __cfaehm_cancel_stack( exception_t * exception ) {
224        __cfaehm_allocate_exception( exception );
225
226        struct exception_context_t * context = this_exception_context();
227        struct __cfaehm_node * node = EXCEPT_TO_NODE(context->current_exception);
228
229        // Preform clean-up of any extra active exceptions.
230        while ( node->next ) {
231                struct __cfaehm_node * to_free = node->next;
232                node->next = to_free->next;
233                exception_t * except = NODE_TO_EXCEPT( to_free );
234                except->virtual_table->free( except );
235            free( to_free );
236        }
237
238        _Unwind_Reason_Code ret;
239        ret = __cfaehm_cancellation_unwind( &node->unwind_exception );
240        printf("UNWIND ERROR %d after force unwind\n", ret);
241        abort();
242}
243
244
245// TERMINATION ===============================================================
246
247// If this isn't a rethrow (*except==0), delete the provided exception.
248void __cfaehm_cleanup_terminate( void * except ) {
249        if ( *(void**)except ) __cfaehm_delete_exception( *(exception_t **)except );
250}
251
252static void __cfaehm_cleanup_default( exception_t ** except ) {
253        __cfaehm_delete_exception( *except );
254        *except = NULL;
255}
256
257// The exception that is being thrown must already be stored.
258static void __cfaehm_begin_unwind(void(*defaultHandler)(exception_t *)) {
259        struct exception_context_t * context = this_exception_context();
260        if ( NULL == context->current_exception ) {
261                printf("UNWIND ERROR missing exception in begin unwind\n");
262                abort();
263        }
264        struct _Unwind_Exception * storage =
265                &EXCEPT_TO_NODE(context->current_exception)->unwind_exception;
266
267        // Call stdlibc to raise the exception
268        __cfadbg_print_safe(exception, "Begin unwinding (storage &p, context %p)\n", storage, context);
269        _Unwind_Reason_Code ret = _Unwind_RaiseException( storage );
270
271        // If we reach here it means something happened. For resumption to work we need to find a way
272        // to return back to here. Most of them will probably boil down to setting a global flag and
273        // making the phase 1 either stop or fail. Causing an error on purpose may help avoiding
274        // unnecessary work but it might have some weird side effects. If we just pretend no handler
275        // was found that would work but may be expensive for no reason since we will always search
276        // the whole stack.
277
278        // We did not simply reach the end of the stack without finding a handler. This is an error.
279        if ( ret != _URC_END_OF_STACK ) {
280                printf("UNWIND ERROR %d after raise exception\n", ret);
281                abort();
282        }
283
284        // No handler found, go to the default operation.
285        __cfadbg_print_safe(exception, "Uncaught exception %p\n", storage);
286
287        __attribute__((cleanup(__cfaehm_cleanup_default)))
288        exception_t * exception = context->current_exception;
289        defaultHandler( exception );
290}
291
292void __cfaehm_throw_terminate( exception_t * val, void (*defaultHandler)(exception_t *) ) {
293        __cfadbg_print_safe(exception, "Throwing termination exception\n");
294
295        __cfaehm_allocate_exception( val );
296        __cfaehm_begin_unwind( defaultHandler );
297}
298
299static __attribute__((noreturn)) void __cfaehm_rethrow_adapter( exception_t * except ) {
300        // TODO: Print some error message.
301        (void)except;
302        abort();
303}
304
305void __cfaehm_rethrow_terminate(void) {
306        __cfadbg_print_safe(exception, "Rethrowing termination exception\n");
307
308        __cfaehm_begin_unwind( __cfaehm_rethrow_adapter );
309        abort();
310}
311
312#if defined( __x86_64 ) || defined( __i386 )
313// This is our personality routine. For every stack frame annotated with
314// ".cfi_personality 0x3,__gcfa_personality_v0" this function will be called twice when unwinding.
315//  Once in the search phase and once in the cleanup phase.
316_Unwind_Reason_Code __gcfa_personality_v0(
317                int version,
318                _Unwind_Action actions,
319                unsigned long long exception_class,
320                struct _Unwind_Exception * unwind_exception,
321                struct _Unwind_Context * unwind_context)
322{
323
324        //__cfadbg_print_safe(exception, "CFA: 0x%lx\n", _Unwind_GetCFA(context));
325        __cfadbg_print_safe(exception, "Personality function (%d, %x, %llu, %p, %p):",
326                        version, actions, exception_class, unwind_exception, unwind_context);
327
328        // Verify that actions follow the rules we expect.
329        // This function should never be called at the end of the stack.
330        verify(!(actions & _UA_END_OF_STACK));
331        // Either only the search phase flag is set or...
332        if (actions & _UA_SEARCH_PHASE) {
333                verify(actions == _UA_SEARCH_PHASE);
334                __cfadbg_print_safe(exception, " lookup phase");
335        // ... we are in clean-up phase.
336        } else {
337                verify(actions & _UA_CLEANUP_PHASE);
338                __cfadbg_print_safe(exception, " cleanup phase");
339                // We shouldn't be the handler frame during forced unwind.
340                if (actions & _UA_HANDLER_FRAME) {
341                        verify(!(actions & _UA_FORCE_UNWIND));
342                        __cfadbg_print_safe(exception, " (handler frame)");
343                } else if (actions & _UA_FORCE_UNWIND) {
344                        __cfadbg_print_safe(exception, " (force unwind)");
345                }
346        }
347
348        // Get a pointer to the language specific data from which we will read what we need
349        const unsigned char * lsd = _Unwind_GetLanguageSpecificData( unwind_context );
350
351        if ( !lsd ) {   //Nothing to do, keep unwinding
352                printf(" no LSD");
353                goto UNWIND;
354        }
355
356        // Get the instuction pointer and a reading pointer into the exception table
357        lsda_header_info lsd_info;
358        const unsigned char * cur_ptr = parse_lsda_header(unwind_context, lsd, &lsd_info);
359        _Unwind_Ptr instruction_ptr = _Unwind_GetIP(unwind_context);
360
361        struct exception_context_t * context = this_exception_context();
362
363        // Linearly search the table for stuff to do
364        while ( cur_ptr < lsd_info.action_table ) {
365                _Unwind_Ptr callsite_start;
366                _Unwind_Ptr callsite_len;
367                _Unwind_Ptr callsite_landing_pad;
368                _uleb128_t  callsite_action;
369
370                // Decode the common stuff we have in here
371                cur_ptr = read_encoded_value(0, lsd_info.call_site_encoding, cur_ptr, &callsite_start);
372                cur_ptr = read_encoded_value(0, lsd_info.call_site_encoding, cur_ptr, &callsite_len);
373                cur_ptr = read_encoded_value(0, lsd_info.call_site_encoding, cur_ptr, &callsite_landing_pad);
374                cur_ptr = read_uleb128(cur_ptr, &callsite_action);
375
376                // Have we reach the correct frame info yet?
377                if ( lsd_info.Start + callsite_start + callsite_len < instruction_ptr ) {
378#ifdef __CFA_DEBUG_PRINT__
379                        void * ls = (void*)lsd_info.Start;
380                        void * cs = (void*)callsite_start;
381                        void * cl = (void*)callsite_len;
382                        void * bp = (void*)lsd_info.Start + callsite_start;
383                        void * ep = (void*)lsd_info.Start + callsite_start + callsite_len;
384                        void * ip = (void*)instruction_ptr;
385                        __cfadbg_print_safe(exception, "\nfound %p - %p (%p, %p, %p), looking for %p\n",
386                                        bp, ep, ls, cs, cl, ip);
387#endif // __CFA_DEBUG_PRINT__
388                        continue;
389                }
390
391                // Have we gone too far?
392                if ( lsd_info.Start + callsite_start > instruction_ptr ) {
393                        printf(" gone too far");
394                        break;
395                }
396
397                // Check for what we must do:
398                if ( 0 == callsite_landing_pad ) {
399                        // Nothing to do, move along
400                        __cfadbg_print_safe(exception, " no landing pad");
401                } else if (actions & _UA_SEARCH_PHASE) {
402                        // In search phase, these means we found a potential handler we must check.
403
404                        // We have arbitrarily decided that 0 means nothing to do and 1 means there is
405                        // a potential handler. This doesn't seem to conflict the gcc default behavior.
406                        if (callsite_action != 0) {
407                                // Now we want to run some code to see if the handler matches
408                                // This is the tricky part where we want to the power to run arbitrary code
409                                // However, generating a new exception table entry and try routine every time
410                                // is way more expansive than we might like
411                                // The information we have is :
412                                //  - The GR (Series of registers)
413                                //    GR1=GP Global Pointer of frame ref by context
414                                //  - The instruction pointer
415                                //  - The instruction pointer info (???)
416                                //  - The CFA (Canonical Frame Address)
417                                //  - The BSP (Probably the base stack pointer)
418
419                                // The current apprach uses one exception table entry per try block
420                                _uleb128_t imatcher;
421                                // Get the relative offset to the {...}?
422                                cur_ptr = read_uleb128(cur_ptr, &imatcher);
423
424                                _Unwind_Word match_pos =
425#                               if defined( __x86_64 )
426                                    _Unwind_GetCFA(unwind_context) + 8;
427#                               elif defined( __i386 )
428                                    _Unwind_GetCFA(unwind_context) + 24;
429#                               elif defined( __ARM_ARCH )
430#                                   warning FIX ME: check if anything needed for ARM
431                                    42;
432#                               endif
433                                int (*matcher)(exception_t *) = *(int(**)(exception_t *))match_pos;
434
435                                int index = matcher(context->current_exception);
436                                _Unwind_Reason_Code ret = (0 == index)
437                                        ? _URC_CONTINUE_UNWIND : _URC_HANDLER_FOUND;
438                                UNWIND_TO_NODE(unwind_exception)->handler_index = index;
439
440                                // Based on the return value, check if we matched the exception
441                                if (ret == _URC_HANDLER_FOUND) {
442                                        __cfadbg_print_safe(exception, " handler found\n");
443                                } else {
444                                        // TODO: Continue the search if there is more in the table.
445                                        __cfadbg_print_safe(exception, " no handler\n");
446                                }
447                                return ret;
448                        }
449
450                        // This is only a cleanup handler, ignore it
451                        __cfadbg_print_safe(exception, " no action");
452                } else {
453                        // In clean-up phase, no destructors here but this could be the handler.
454
455                        if ( (callsite_action != 0) && !(actions & _UA_HANDLER_FRAME) ){
456                                // If this is a potential exception handler
457                                // but not the one that matched the exception in the seach phase,
458                                // just ignore it
459                                goto UNWIND;
460                        }
461
462                        // We need to run some clean-up or a handler
463                        // These statment do the right thing but I don't know any specifics at all
464                        _Unwind_SetGR( unwind_context, __builtin_eh_return_data_regno(0),
465                                (_Unwind_Ptr)unwind_exception );
466                        _Unwind_SetGR( unwind_context, __builtin_eh_return_data_regno(1), 0 );
467
468                        // I assume this sets the instruction pointer to the adress of the landing pad
469                        // It doesn't actually set it, it only state the value that needs to be set once we
470                        // return _URC_INSTALL_CONTEXT
471                        _Unwind_SetIP( unwind_context, ((lsd_info.LPStart) + (callsite_landing_pad)) );
472
473                        __cfadbg_print_safe(exception, " action\n");
474
475                        // Return have some action to run
476                        return _URC_INSTALL_CONTEXT;
477                }
478        }
479        // No handling found
480        __cfadbg_print_safe(exception, " table end reached");
481
482        UNWIND:
483        __cfadbg_print_safe(exception, " unwind\n");
484
485        // Keep unwinding the stack
486        return _URC_CONTINUE_UNWIND;
487}
488
489#pragma GCC push_options
490#pragma GCC optimize(0)
491
492// Try statements are hoisted out see comments for details. While this could probably be unique
493// and simply linked from libcfa but there is one problem left, see the exception table for details
494__attribute__((noinline))
495void __cfaehm_try_terminate(void (*try_block)(),
496                void (*catch_block)(int index, exception_t * except),
497                __attribute__((unused)) int (*match_block)(exception_t * except)) {
498        //! volatile int xy = 0;
499        //! printf("%p %p %p %p\n", &try_block, &catch_block, &match_block, &xy);
500
501        // Setup the personality routine and exception table.
502        // Unforturnately these clobber gcc cancellation support which means we can't get access to
503        // the attribute cleanup tables at the same time. We would have to inspect the assembly to
504        // create a new set ourselves.
505#ifdef __PIC__
506        asm volatile (".cfi_personality 0x9b,CFA.ref.__gcfa_personality_v0");
507        asm volatile (".cfi_lsda 0x1b, .LLSDACFA2");
508#else
509        asm volatile (".cfi_personality 0x3,__gcfa_personality_v0");
510        asm volatile (".cfi_lsda 0x3, .LLSDACFA2");
511#endif
512
513        // Label which defines the start of the area for which the handler is setup.
514        asm volatile (".TRYSTART:");
515
516        // The actual statements of the try blocks
517        try_block();
518
519        // asm statement to prevent deadcode removal
520        asm volatile goto ("" : : : : CATCH );
521
522        // Normal return for when there is no throw.
523        return;
524
525        // Exceptionnal path
526        CATCH : __attribute__(( unused ));
527        // Label which defines the end of the area for which the handler is setup.
528        asm volatile (".TRYEND:");
529        // Label which defines the start of the exception landing pad. Basically what is called when
530        // the exception is caught. Note, if multiple handlers are given, the multiplexing should be
531        // done by the generated code, not the exception runtime.
532        asm volatile (".CATCH:");
533
534        // Exception handler
535        // Note: Saving the exception context on the stack breaks termination exceptions.
536        catch_block( EXCEPT_TO_NODE( this_exception_context()->current_exception )->handler_index,
537                     this_exception_context()->current_exception );
538}
539
540// Exception table data we need to generate. While this is almost generic, the custom data refers
541// to {*}try_terminate, which is no way generic. Some more works need to be done if we want to
542// have a single call to the try routine.
543
544#ifdef __PIC__
545asm (
546        // HEADER
547        ".LFECFA1:\n"
548        "       .globl  __gcfa_personality_v0\n"
549        "       .section        .gcc_except_table,\"a\",@progbits\n"
550        // TABLE HEADER (important field is the BODY length at the end)
551        ".LLSDACFA2:\n"
552        "       .byte   0xff\n"
553        "       .byte   0xff\n"
554        "       .byte   0x1\n"
555        "       .uleb128 .LLSDACSECFA2-.LLSDACSBCFA2\n"
556        // BODY (language specific data)
557        // This uses language specific data and can be modified arbitrarily
558        // We use handled area offset, handled area length,
559        // handler landing pad offset and 1 (action code, gcc seems to use 0).
560        ".LLSDACSBCFA2:\n"
561        "       .uleb128 .TRYSTART-__cfaehm_try_terminate\n"
562        "       .uleb128 .TRYEND-.TRYSTART\n"
563        "       .uleb128 .CATCH-__cfaehm_try_terminate\n"
564        "       .uleb128 1\n"
565        ".LLSDACSECFA2:\n"
566        // TABLE FOOTER
567        "       .text\n"
568        "       .size   __cfaehm_try_terminate, .-__cfaehm_try_terminate\n"
569);
570
571// Somehow this piece of helps with the resolution of debug symbols.
572__attribute__((unused)) static const int dummy = 0;
573
574asm (
575        // Add a hidden symbol which points at the function.
576        "       .hidden CFA.ref.__gcfa_personality_v0\n"
577        "       .weak   CFA.ref.__gcfa_personality_v0\n"
578        // No clue what this does specifically
579        "       .section        .data.rel.local.CFA.ref.__gcfa_personality_v0,\"awG\",@progbits,CFA.ref.__gcfa_personality_v0,comdat\n"
580        "       .align 8\n"
581        "       .type CFA.ref.__gcfa_personality_v0, @object\n"
582        "       .size CFA.ref.__gcfa_personality_v0, 8\n"
583        "CFA.ref.__gcfa_personality_v0:\n"
584#if defined( __x86_64 )
585        "       .quad __gcfa_personality_v0\n"
586#else // then __i386
587        "       .long __gcfa_personality_v0\n"
588#endif
589);
590#else // __PIC__
591asm (
592        // HEADER
593        ".LFECFA1:\n"
594        "       .globl  __gcfa_personality_v0\n"
595        "       .section        .gcc_except_table,\"a\",@progbits\n"
596        // TABLE HEADER (important field is the BODY length at the end)
597        ".LLSDACFA2:\n"
598        "       .byte   0xff\n"
599        "       .byte   0xff\n"
600        "       .byte   0x1\n"
601        "       .uleb128 .LLSDACSECFA2-.LLSDACSBCFA2\n"
602        // BODY (language specific data)
603        ".LLSDACSBCFA2:\n"
604        //      Handled area start (relative to start of function)
605        "       .uleb128 .TRYSTART-__cfaehm_try_terminate\n"
606        //      Handled area length
607        "       .uleb128 .TRYEND-.TRYSTART\n"
608        //      Handler landing pad address (relative to start of function)
609        "       .uleb128 .CATCH-__cfaehm_try_terminate\n"
610        //      Action code, gcc seems to always use 0.
611        "       .uleb128 1\n"
612        // TABLE FOOTER
613        ".LLSDACSECFA2:\n"
614        "       .text\n"
615        "       .size   __cfaehm_try_terminate, .-__cfaehm_try_terminate\n"
616        "       .ident  \"GCC: (Ubuntu 6.2.0-3ubuntu11~16.04) 6.2.0 20160901\"\n"
617        "       .section        .note.GNU-stack,\"x\",@progbits\n"
618);
619#endif // __PIC__
620
621#pragma GCC pop_options
622
623#elif defined( __ARM_ARCH )
624_Unwind_Reason_Code __gcfa_personality_v0(
625                int version,
626                _Unwind_Action actions,
627                unsigned long long exception_class,
628                struct _Unwind_Exception * unwind_exception,
629                struct _Unwind_Context * unwind_context) {
630        return _URC_CONTINUE_UNWIND;
631}
632
633__attribute__((noinline))
634void __cfaehm_try_terminate(void (*try_block)(),
635                void (*catch_block)(int index, exception_t * except),
636                __attribute__((unused)) int (*match_block)(exception_t * except)) {
637}
638#else
639        #error unsupported hardware architecture
640#endif // __x86_64 || __i386
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