source: libcfa/src/exception.c @ 04b73b6

ADTarm-ehast-experimentalenumforall-pointer-decayjacob/cs343-translationnew-astnew-ast-unique-exprpthread-emulationqualifiedEnum
Last change on this file since 04b73b6 was 381132b, checked in by Andrew Beach <ajbeach@…>, 4 years ago

Default handlers for uncaught exceptions are now run at the top of the stack. There was an error but it seemed to disappear when I recompiled the code.

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[fa4805f]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
[3090127]11// Last Modified By : Andrew Beach
[8ad5752]12// Last Modified On : Thr May 21 12:18:00 2020
13// Update Count     : 20
[fa4805f]14//
15
[9640813]16// Normally we would get this from the CFA prelude.
[cbce272]17#include <stddef.h> // for size_t
18
[fa4805f]19#include "exception.h"
20
[9640813]21// Implementation of the secret header is hardware dependent.
22#if !( defined( __x86_64 ) || defined( __i386 ) )
23#error Exception Handling: No known architecture detected.
24#endif
[fa4805f]25
26#include <stdlib.h>
27#include <stdio.h>
28#include <unwind.h>
[73abe95]29#include <bits/debug.hfa>
[a201f7b]30#include "stdhdr/assert.h"
[fa4805f]31
[b947fb2]32// FIX ME: temporary hack to keep ARM build working
33#ifndef _URC_FATAL_PHASE1_ERROR
[73530d9]34#define _URC_FATAL_PHASE1_ERROR 3
[b947fb2]35#endif // ! _URC_FATAL_PHASE1_ERROR
36#ifndef _URC_FATAL_PHASE2_ERROR
37#define _URC_FATAL_PHASE2_ERROR 2
38#endif // ! _URC_FATAL_PHASE2_ERROR
39
[fa4805f]40#include "lsda.h"
41
[73530d9]42/* The exception class for our exceptions. Because of the vendor component
43 * its value would not be standard.
44 * Vendor: UWPL
45 * Language: CFA\0
46 */
47const _Unwind_Exception_Class __cfaehm_exception_class = 0x4c50575500414643;
[cbce272]48
49// Base exception vtable is abstract, you should not have base exceptions.
[3090127]50struct __cfaehm_base_exception_t_vtable
51                ___cfaehm_base_exception_t_vtable_instance = {
[cbce272]52        .parent = NULL,
53        .size = 0,
54        .copy = NULL,
55        .free = NULL,
56        .msg = NULL
57};
58
59
[fa4805f]60// Temperary global exception context. Does not work with concurency.
[86d5ba7c]61struct exception_context_t {
[3eb5a478]62        struct __cfaehm_try_resume_node * top_resume;
[fa4805f]63
[3eb5a478]64        exception_t * current_exception;
65        int current_handler_index;
66} static shared_stack = {NULL, NULL, 0};
[86d5ba7c]67
68// Get the current exception context.
69// There can be a single global until multithreading occurs, then each stack
70// needs its own. It will have to be updated to handle that.
[9cb89b87]71struct exception_context_t * this_exception_context() {
[86d5ba7c]72        return &shared_stack;
73}
[fa4805f]74
75
76// RESUMPTION ================================================================
77
[f1b6671]78static void reset_top_resume(struct __cfaehm_try_resume_node ** store) {
79        this_exception_context()->top_resume = *store;
80}
81
[046a890]82void __cfaehm_throw_resume(exception_t * except, void (*defaultHandler)(exception_t *)) {
[2a3b019]83        struct exception_context_t * context = this_exception_context();
[fa4805f]84
[851fd92]85        __cfadbg_print_safe(exception, "Throwing resumption exception\n");
[fa4805f]86
[381132b]87        {
88                __attribute__((cleanup(reset_top_resume)))
89                struct __cfaehm_try_resume_node * original_head = context->top_resume;
90                struct __cfaehm_try_resume_node * current = context->top_resume;
91
92                for ( ; current ; current = current->next) {
93                        context->top_resume = current->next;
94                        if (current->handler(except)) {
95                                return;
96                        }
[fa4805f]97                }
[381132b]98        } // End the search and return to the top of the stack.
[fa4805f]99
[046a890]100        // No handler found, fall back to the default operation.
[851fd92]101        __cfadbg_print_safe(exception, "Unhandled exception\n");
[046a890]102        defaultHandler(except);
[fa4805f]103}
104
[eb46fdf]105// Do we control where exceptions get thrown even with concurency?
106// If not these are not quite thread safe, the cleanup hook has to
107// be added after the node is built but before it is made the top node.
[b947fb2]108
[3090127]109void __cfaehm_try_resume_setup(struct __cfaehm_try_resume_node * node,
[0304215a]110                        _Bool (*handler)(exception_t * except)) {
[2a3b019]111        struct exception_context_t * context = this_exception_context();
112        node->next = context->top_resume;
[307a732]113        node->handler = handler;
[2a3b019]114        context->top_resume = node;
[fa4805f]115}
116
[3090127]117void __cfaehm_try_resume_cleanup(struct __cfaehm_try_resume_node * node) {
[2a3b019]118        struct exception_context_t * context = this_exception_context();
119        context->top_resume = node->next;
[fa4805f]120}
121
122
[2922871]123// MEMORY MANAGEMENT =========================================================
[ff7ff14a]124
[73530d9]125// How to clean up an exception in various situations.
126static void __cfaehm_exception_cleanup(
127                _Unwind_Reason_Code reason,
128                struct _Unwind_Exception * exception) {
129        switch (reason) {
130        case _URC_FOREIGN_EXCEPTION_CAUGHT:
131                // This one we could clean-up to allow cross-language exceptions.
132        case _URC_FATAL_PHASE1_ERROR:
133        case _URC_FATAL_PHASE2_ERROR:
134        default:
135                abort();
136        }
137}
138
139// We need a piece of storage to raise the exception, for now its a single
140// piece.
141static struct _Unwind_Exception this_exception_storage;
142
[3090127]143struct __cfaehm_node {
144        struct __cfaehm_node * next;
[ff7ff14a]145};
146
[0304215a]147#define NODE_TO_EXCEPT(node) ((exception_t *)(1 + (node)))
[3090127]148#define EXCEPT_TO_NODE(except) ((struct __cfaehm_node *)(except) - 1)
[86d5ba7c]149
150// Creates a copy of the indicated exception and sets current_exception to it.
[3090127]151static void __cfaehm_allocate_exception( exception_t * except ) {
[86d5ba7c]152        struct exception_context_t * context = this_exception_context();
153
[ff7ff14a]154        // Allocate memory for the exception.
[3090127]155        struct __cfaehm_node * store = malloc(
156                sizeof( struct __cfaehm_node ) + except->virtual_table->size );
[ff7ff14a]157
158        if ( ! store ) {
159                // Failure: cannot allocate exception. Terminate thread.
160                abort(); // <- Although I think it might be the process.
[86d5ba7c]161        }
162
[ff7ff14a]163        // Add the node to the list:
164        store->next = EXCEPT_TO_NODE(context->current_exception);
165        context->current_exception = NODE_TO_EXCEPT(store);
166
[86d5ba7c]167        // Copy the exception to storage.
[cbce272]168        except->virtual_table->copy( context->current_exception, except );
[73530d9]169
170        // Set up the exception storage.
171        this_exception_storage.exception_class = __cfaehm_exception_class;
172        this_exception_storage.exception_cleanup = __cfaehm_exception_cleanup;
[86d5ba7c]173}
174
175// Delete the provided exception, unsetting current_exception if relivant.
[3090127]176static void __cfaehm_delete_exception( exception_t * except ) {
[86d5ba7c]177        struct exception_context_t * context = this_exception_context();
178
[851fd92]179        __cfadbg_print_safe(exception, "Deleting Exception\n");
[ff7ff14a]180
181        // Remove the exception from the list.
[3090127]182        struct __cfaehm_node * to_free = EXCEPT_TO_NODE(except);
183        struct __cfaehm_node * node;
[86d5ba7c]184
185        if ( context->current_exception == except ) {
[ff7ff14a]186                node = to_free->next;
187                context->current_exception = (node) ? NODE_TO_EXCEPT(node) : 0;
[86d5ba7c]188        } else {
[ff7ff14a]189                node = EXCEPT_TO_NODE(context->current_exception);
190                // It may always be in the first or second position.
[9cb89b87]191                while ( to_free != node->next ) {
[ff7ff14a]192                        node = node->next;
193                }
194                node->next = to_free->next;
[86d5ba7c]195        }
[ff7ff14a]196
197        // Free the old exception node.
[cbce272]198        except->virtual_table->free( except );
[ff7ff14a]199        free( to_free );
[86d5ba7c]200}
201
[2922871]202// CANCELLATION ==============================================================
[fa4805f]203
204// Function needed by force unwind
205// It basically says to unwind the whole stack and then exit when we reach the end of the stack
206static _Unwind_Reason_Code _Stop_Fn(
207                int version,
208                _Unwind_Action actions,
[3090127]209                _Unwind_Exception_Class exception_class,
[fa4805f]210                struct _Unwind_Exception * unwind_exception,
[2a3b019]211                struct _Unwind_Context * unwind_context,
212                void * stop_param) {
[a201f7b]213        // Verify actions follow the rules we expect.
[851fd92]214        verify((actions & _UA_CLEANUP_PHASE) && (actions & _UA_FORCE_UNWIND));
[a201f7b]215        verify(!(actions & (_UA_SEARCH_PHASE | _UA_HANDER_FRAME)));
[fa4805f]216
[a201f7b]217        if ( actions & _UA_END_OF_STACK ) {
218                exit(1);
219        } else {
220                return _URC_NO_REASON;
221        }
[fa4805f]222}
223
[2922871]224// Cancel the current stack, prefroming approprate clean-up and messaging.
[979df46]225void __cfaehm_cancel_stack( exception_t * exception ) {
[2922871]226        // TODO: Detect current stack and pick a particular stop-function.
227        _Unwind_Reason_Code ret;
228        ret = _Unwind_ForcedUnwind( &this_exception_storage, _Stop_Fn, (void*)0x22 );
229        printf("UNWIND ERROR %d after force unwind\n", ret);
230        abort();
231}
232
233
234// TERMINATION ===============================================================
235
236// If this isn't a rethrow (*except==0), delete the provided exception.
237void __cfaehm_cleanup_terminate( void * except ) {
238        if ( *(void**)except ) __cfaehm_delete_exception( *(exception_t **)except );
239}
240
[8ad5752]241static void __cfaehm_cleanup_default( exception_t ** except ) {
242        __cfaehm_delete_exception( *except );
243        *except = NULL;
244}
245
[86d5ba7c]246// The exception that is being thrown must already be stored.
[046a890]247static void __cfaehm_begin_unwind(void(*defaultHandler)(exception_t *)) {
[8ad5752]248        struct exception_context_t * context = this_exception_context();
249        struct _Unwind_Exception * storage = &this_exception_storage;
250        if ( NULL == context->current_exception ) {
[86d5ba7c]251                printf("UNWIND ERROR missing exception in begin unwind\n");
252                abort();
253        }
[fa4805f]254
255        // Call stdlibc to raise the exception
[8ad5752]256        __cfadbg_print_safe(exception, "Begin unwinding (storage &p, context %p)\n", storage, context);
257        _Unwind_Reason_Code ret = _Unwind_RaiseException( storage );
[fa4805f]258
[eb46fdf]259        // If we reach here it means something happened. For resumption to work we need to find a way
260        // to return back to here. Most of them will probably boil down to setting a global flag and
261        // making the phase 1 either stop or fail. Causing an error on purpose may help avoiding
262        // unnecessary work but it might have some weird side effects. If we just pretend no handler
263        // was found that would work but may be expensive for no reason since we will always search
264        // the whole stack.
[fa4805f]265
[8ad5752]266        // We did not simply reach the end of the stack without finding a handler. This is an error.
267        if ( ret != _URC_END_OF_STACK ) {
268                printf("UNWIND ERROR %d after raise exception\n", ret);
269                abort();
[fa4805f]270        }
271
[8ad5752]272        // No handler found, go to the default operation.
273        __cfadbg_print_safe(exception, "Uncaught exception %p\n", storage);
274
275        __attribute__((cleanup(__cfaehm_cleanup_default)))
276        exception_t * exception = context->current_exception;
277        defaultHandler( exception );
[fa4805f]278}
279
[046a890]280void __cfaehm_throw_terminate( exception_t * val, void (*defaultHandler)(exception_t *) ) {
[851fd92]281        __cfadbg_print_safe(exception, "Throwing termination exception\n");
[86d5ba7c]282
[3090127]283        __cfaehm_allocate_exception( val );
[046a890]284        __cfaehm_begin_unwind( defaultHandler );
285}
286
287static __attribute__((noreturn)) void __cfaehm_rethrow_adapter( exception_t * except ) {
288        // TODO: Print some error message.
289        (void)except;
290        abort();
[86d5ba7c]291}
292
[3090127]293void __cfaehm_rethrow_terminate(void) {
[851fd92]294        __cfadbg_print_safe(exception, "Rethrowing termination exception\n");
[fa4805f]295
[046a890]296        __cfaehm_begin_unwind( __cfaehm_rethrow_adapter );
297        abort();
[fa4805f]298}
299
[eb46fdf]300// This is our personality routine. For every stack frame annotated with
301// ".cfi_personality 0x3,__gcfa_personality_v0" this function will be called twice when unwinding.
302//  Once in the search phase and once in the cleanup phase.
[3090127]303_Unwind_Reason_Code __gcfa_personality_v0(
304                int version,
305                _Unwind_Action actions,
306                unsigned long long exception_class,
307                struct _Unwind_Exception * unwind_exception,
308                struct _Unwind_Context * unwind_context)
[fa4805f]309{
310
[851fd92]311        //__cfadbg_print_safe(exception, "CFA: 0x%lx\n", _Unwind_GetCFA(context));
312        __cfadbg_print_safe(exception, "Personality function (%d, %x, %llu, %p, %p):",
[3090127]313                        version, actions, exception_class, unwind_exception, unwind_context);
[fa4805f]314
[a201f7b]315        // Verify that actions follow the rules we expect.
316        // This function should never be called at the end of the stack.
317        verify(!(actions & _UA_END_OF_STACK));
318        // Either only the search phase flag is set or...
[fa4805f]319        if (actions & _UA_SEARCH_PHASE) {
[a201f7b]320                verify(actions == _UA_SEARCH_PHASE);
[851fd92]321                __cfadbg_print_safe(exception, " lookup phase");
[a201f7b]322        // ... we are in clean-up phase.
323        } else {
324                verify(actions & _UA_CLEANUP_PHASE);
[851fd92]325                __cfadbg_print_safe(exception, " cleanup phase");
[a201f7b]326                // We shouldn't be the handler frame during forced unwind.
327                if (actions & _UA_HANDLER_FRAME) {
328                        verify(!(actions & _UA_FORCE_UNWIND));
[851fd92]329                        __cfadbg_print_safe(exception, " (handler frame)");
[a201f7b]330                } else if (actions & _UA_FORCE_UNWIND) {
[851fd92]331                        __cfadbg_print_safe(exception, " (force unwind)");
[a201f7b]332                }
[fa4805f]333        }
334
335        // Get a pointer to the language specific data from which we will read what we need
[9cb89b87]336        const unsigned char * lsd = _Unwind_GetLanguageSpecificData( unwind_context );
[fa4805f]337
[9cb89b87]338        if ( !lsd ) {   //Nothing to do, keep unwinding
[fa4805f]339                printf(" no LSD");
340                goto UNWIND;
341        }
342
343        // Get the instuction pointer and a reading pointer into the exception table
344        lsda_header_info lsd_info;
[2a3b019]345        const unsigned char * cur_ptr = parse_lsda_header(unwind_context, lsd, &lsd_info);
346        _Unwind_Ptr instruction_ptr = _Unwind_GetIP(unwind_context);
347
348        struct exception_context_t * context = this_exception_context();
[fa4805f]349
350        // Linearly search the table for stuff to do
[9cb89b87]351        while ( cur_ptr < lsd_info.action_table ) {
[fa4805f]352                _Unwind_Ptr callsite_start;
353                _Unwind_Ptr callsite_len;
354                _Unwind_Ptr callsite_landing_pad;
355                _uleb128_t  callsite_action;
356
357                // Decode the common stuff we have in here
[eb46fdf]358                cur_ptr = read_encoded_value(0, lsd_info.call_site_encoding, cur_ptr, &callsite_start);
359                cur_ptr = read_encoded_value(0, lsd_info.call_site_encoding, cur_ptr, &callsite_len);
360                cur_ptr = read_encoded_value(0, lsd_info.call_site_encoding, cur_ptr, &callsite_landing_pad);
361                cur_ptr = read_uleb128(cur_ptr, &callsite_action);
[fa4805f]362
363                // Have we reach the correct frame info yet?
[9cb89b87]364                if ( lsd_info.Start + callsite_start + callsite_len < instruction_ptr ) {
[e9145a3]365#ifdef __CFA_DEBUG_PRINT__
[fa4805f]366                        void * ls = (void*)lsd_info.Start;
367                        void * cs = (void*)callsite_start;
368                        void * cl = (void*)callsite_len;
369                        void * bp = (void*)lsd_info.Start + callsite_start;
370                        void * ep = (void*)lsd_info.Start + callsite_start + callsite_len;
371                        void * ip = (void*)instruction_ptr;
[851fd92]372                        __cfadbg_print_safe(exception, "\nfound %p - %p (%p, %p, %p), looking for %p\n",
[eb46fdf]373                                        bp, ep, ls, cs, cl, ip);
[e9145a3]374#endif // __CFA_DEBUG_PRINT__
[fa4805f]375                        continue;
376                }
377
[eb46fdf]378                // Have we gone too far?
[9cb89b87]379                if ( lsd_info.Start + callsite_start > instruction_ptr ) {
[fa4805f]380                        printf(" gone too far");
381                        break;
382                }
383
[9cb89b87]384                // Check for what we must do:
[2a3b019]385                if ( 0 == callsite_landing_pad ) {
386                        // Nothing to do, move along
[851fd92]387                        __cfadbg_print_safe(exception, " no landing pad");
[9cb89b87]388                } else if (actions & _UA_SEARCH_PHASE) {
389                        // In search phase, these means we found a potential handler we must check.
390
391                        // We have arbitrarily decided that 0 means nothing to do and 1 means there is
392                        // a potential handler. This doesn't seem to conflict the gcc default behavior.
393                        if (callsite_action != 0) {
394                                // Now we want to run some code to see if the handler matches
395                                // This is the tricky part where we want to the power to run arbitrary code
396                                // However, generating a new exception table entry and try routine every time
397                                // is way more expansive than we might like
398                                // The information we have is :
399                                //  - The GR (Series of registers)
400                                //    GR1=GP Global Pointer of frame ref by context
401                                //  - The instruction pointer
402                                //  - The instruction pointer info (???)
403                                //  - The CFA (Canonical Frame Address)
404                                //  - The BSP (Probably the base stack pointer)
405
406                                // The current apprach uses one exception table entry per try block
407                                _uleb128_t imatcher;
408                                // Get the relative offset to the {...}?
409                                cur_ptr = read_uleb128(cur_ptr, &imatcher);
410
411#                               if defined( __x86_64 )
412                                _Unwind_Word match_pos = _Unwind_GetCFA(unwind_context) + 8;
413#                               elif defined( __i386 )
414                                _Unwind_Word match_pos = _Unwind_GetCFA(unwind_context) + 24;
415#                               endif
416                                int (*matcher)(exception_t *) = *(int(**)(exception_t *))match_pos;
417
418                                int index = matcher(context->current_exception);
419                                _Unwind_Reason_Code ret = (0 == index)
420                                        ? _URC_CONTINUE_UNWIND : _URC_HANDLER_FOUND;
421                                context->current_handler_index = index;
422
423                                // Based on the return value, check if we matched the exception
424                                if (ret == _URC_HANDLER_FOUND) {
[851fd92]425                                        __cfadbg_print_safe(exception, " handler found\n");
[9cb89b87]426                                } else {
[851fd92]427                                        __cfadbg_print_safe(exception, " no handler\n");
[fa4805f]428                                }
[9cb89b87]429                                return ret;
[fa4805f]430                        }
431
[9cb89b87]432                        // This is only a cleanup handler, ignore it
[851fd92]433                        __cfadbg_print_safe(exception, " no action");
[a201f7b]434                } else {
[9cb89b87]435                        // In clean-up phase, no destructors here but this could be the handler.
436
437                        if ( (callsite_action != 0) && !(actions & _UA_HANDLER_FRAME) ){
438                                // If this is a potential exception handler
439                                // but not the one that matched the exception in the seach phase,
440                                // just ignore it
441                                goto UNWIND;
442                        }
[fa4805f]443
[9cb89b87]444                        // We need to run some clean-up or a handler
445                        // These statment do the right thing but I don't know any specifics at all
446                        _Unwind_SetGR( unwind_context, __builtin_eh_return_data_regno(0),
447                                (_Unwind_Ptr)unwind_exception );
448                        _Unwind_SetGR( unwind_context, __builtin_eh_return_data_regno(1), 0 );
[fa4805f]449
[9cb89b87]450                        // I assume this sets the instruction pointer to the adress of the landing pad
451                        // It doesn't actually set it, it only state the value that needs to be set once we
452                        // return _URC_INSTALL_CONTEXT
453                        _Unwind_SetIP( unwind_context, ((lsd_info.LPStart) + (callsite_landing_pad)) );
[fa4805f]454
[851fd92]455                        __cfadbg_print_safe(exception, " action\n");
[fa4805f]456
[9cb89b87]457                        // Return have some action to run
458                        return _URC_INSTALL_CONTEXT;
[fa4805f]459                }
460        }
461        // No handling found
[851fd92]462        __cfadbg_print_safe(exception, " table end reached");
[fa4805f]463
464        UNWIND:
[851fd92]465        __cfadbg_print_safe(exception, " unwind\n");
[fa4805f]466
467        // Keep unwinding the stack
468        return _URC_CONTINUE_UNWIND;
469}
470
[0f6ac828]471#pragma GCC push_options
[f017af6]472#pragma GCC optimize(0)
[0f6ac828]473
[eb46fdf]474// Try statements are hoisted out see comments for details. While this could probably be unique
475// and simply linked from libcfa but there is one problem left, see the exception table for details
[fa4805f]476__attribute__((noinline))
[3090127]477void __cfaehm_try_terminate(void (*try_block)(),
[0304215a]478                void (*catch_block)(int index, exception_t * except),
479                __attribute__((unused)) int (*match_block)(exception_t * except)) {
[fa4805f]480        //! volatile int xy = 0;
481        //! printf("%p %p %p %p\n", &try_block, &catch_block, &match_block, &xy);
482
[eb46fdf]483        // Setup the personality routine and exception table.
[9cb89b87]484        // Unforturnately these clobber gcc cancellation support which means we can't get access to
485        // the attribute cleanup tables at the same time. We would have to inspect the assembly to
486        // create a new set ourselves.
[3b9c674]487#ifdef __PIC__
488        asm volatile (".cfi_personality 0x9b,CFA.ref.__gcfa_personality_v0");
489        asm volatile (".cfi_lsda 0x1b, .LLSDACFA2");
490#else
[fa4805f]491        asm volatile (".cfi_personality 0x3,__gcfa_personality_v0");
492        asm volatile (".cfi_lsda 0x3, .LLSDACFA2");
[3b9c674]493#endif
[fa4805f]494
[b947fb2]495        // Label which defines the start of the area for which the handler is setup.
[fa4805f]496        asm volatile (".TRYSTART:");
497
498        // The actual statements of the try blocks
499        try_block();
500
501        // asm statement to prevent deadcode removal
502        asm volatile goto ("" : : : : CATCH );
503
[eb46fdf]504        // Normal return for when there is no throw.
[fa4805f]505        return;
506
507        // Exceptionnal path
508        CATCH : __attribute__(( unused ));
[b947fb2]509        // Label which defines the end of the area for which the handler is setup.
[fa4805f]510        asm volatile (".TRYEND:");
[9cb89b87]511        // Label which defines the start of the exception landing pad. Basically what is called when
512        // the exception is caught. Note, if multiple handlers are given, the multiplexing should be
513        // done by the generated code, not the exception runtime.
[fa4805f]514        asm volatile (".CATCH:");
515
516        // Exception handler
[2a3b019]517        // Note: Saving the exception context on the stack breaks termination exceptions.
518        catch_block( this_exception_context()->current_handler_index,
519                     this_exception_context()->current_exception );
[fa4805f]520}
521
[eb46fdf]522// Exception table data we need to generate. While this is almost generic, the custom data refers
523// to {*}try_terminate, which is no way generic. Some more works need to be done if we want to
524// have a single call to the try routine.
[b947fb2]525
[3b9c674]526#ifdef __PIC__
527asm (
528        // HEADER
529        ".LFECFA1:\n"
530        "       .globl  __gcfa_personality_v0\n"
531        "       .section        .gcc_except_table,\"a\",@progbits\n"
532        // TABLE HEADER (important field is the BODY length at the end)
533        ".LLSDACFA2:\n"
534        "       .byte   0xff\n"
535        "       .byte   0xff\n"
536        "       .byte   0x1\n"
537        "       .uleb128 .LLSDACSECFA2-.LLSDACSBCFA2\n"
538        // BODY (language specific data)
539        // This uses language specific data and can be modified arbitrarily
540        // We use handled area offset, handled area length,
541        // handler landing pad offset and 1 (action code, gcc seems to use 0).
542        ".LLSDACSBCFA2:\n"
[3090127]543        "       .uleb128 .TRYSTART-__cfaehm_try_terminate\n"
[3b9c674]544        "       .uleb128 .TRYEND-.TRYSTART\n"
[3090127]545        "       .uleb128 .CATCH-__cfaehm_try_terminate\n"
[3b9c674]546        "       .uleb128 1\n"
547        ".LLSDACSECFA2:\n"
548        // TABLE FOOTER
549        "       .text\n"
[3090127]550        "       .size   __cfaehm_try_terminate, .-__cfaehm_try_terminate\n"
[3b9c674]551);
552
553// Somehow this piece of helps with the resolution of debug symbols.
554__attribute__((unused)) static const int dummy = 0;
555
556asm (
557        // Add a hidden symbol which points at the function.
558        "       .hidden CFA.ref.__gcfa_personality_v0\n"
559        "       .weak   CFA.ref.__gcfa_personality_v0\n"
560        // No clue what this does specifically
561        "       .section        .data.rel.local.CFA.ref.__gcfa_personality_v0,\"awG\",@progbits,CFA.ref.__gcfa_personality_v0,comdat\n"
562        "       .align 8\n"
563        "       .type CFA.ref.__gcfa_personality_v0, @object\n"
564        "       .size CFA.ref.__gcfa_personality_v0, 8\n"
565        "CFA.ref.__gcfa_personality_v0:\n"
566#if defined( __x86_64 )
567        "       .quad __gcfa_personality_v0\n"
568#else // then __i386
[e045590]569        "       .long __gcfa_personality_v0\n"
[3b9c674]570#endif
571);
572#else // __PIC__
[fa4805f]573asm (
[eb46fdf]574        // HEADER
[fa4805f]575        ".LFECFA1:\n"
576        "       .globl  __gcfa_personality_v0\n"
577        "       .section        .gcc_except_table,\"a\",@progbits\n"
[eb46fdf]578        // TABLE HEADER (important field is the BODY length at the end)
579        ".LLSDACFA2:\n"
[fa4805f]580        "       .byte   0xff\n"
581        "       .byte   0xff\n"
582        "       .byte   0x1\n"
[eb46fdf]583        "       .uleb128 .LLSDACSECFA2-.LLSDACSBCFA2\n"
584        // BODY (language specific data)
585        ".LLSDACSBCFA2:\n"
586        //      Handled area start (relative to start of function)
[3090127]587        "       .uleb128 .TRYSTART-__cfaehm_try_terminate\n"
[eb46fdf]588        //      Handled area length
589        "       .uleb128 .TRYEND-.TRYSTART\n"
590        //      Handler landing pad address (relative to start of function)
[3090127]591        "       .uleb128 .CATCH-__cfaehm_try_terminate\n"
[eb46fdf]592        //      Action code, gcc seems to always use 0.
593        "       .uleb128 1\n"
594        // TABLE FOOTER
595        ".LLSDACSECFA2:\n"
596        "       .text\n"
[3090127]597        "       .size   __cfaehm_try_terminate, .-__cfaehm_try_terminate\n"
[fa4805f]598        "       .ident  \"GCC: (Ubuntu 6.2.0-3ubuntu11~16.04) 6.2.0 20160901\"\n"
[3b9c674]599        "       .section        .note.GNU-stack,\"x\",@progbits\n"
[fa4805f]600);
[3b9c674]601#endif // __PIC__
602
603#pragma GCC pop_options
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