MCL/sf/os/kernelhwsrv: comparison kernel/eka/compsupp/aehabi/unwind

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--1:000000000000
+:a41df078684a
+/* unwind_pr.c - ARM-defined model personality routines
+*
+* Copyright 2002-2003 ARM Limited.
+*/
+/*
+Licence
+1. Subject to the provisions of clause 2, ARM hereby grants to LICENSEE a
+perpetual, non-exclusive, nontransferable, royalty free, worldwide licence
+to use this Example Implementation of Exception Handling solely for the
+purpose of developing, having developed, manufacturing, having
+manufactured, offering to sell, selling, supplying or otherwise
+distributing products which comply with the Exception Handling ABI for the
+ARM Architecture specification. All other rights are reserved to ARM or its
+licensors.
+2. THIS EXAMPLE IMPLEMENTATION OF EXCEPTION HANDLING  IS PROVIDED "AS IS"
+WITH NO WARRANTIES EXPRESS, IMPLIED OR STATUTORY, INCLUDING BUT NOT LIMITED
+TO ANY WARRANTY OF SATISFACTORY QUALITY, MERCHANTABILITY, NONINFRINGEMENT
+OR FITNESS FOR A PARTICULAR PURPOSE.
+*/
+/*
+* RCS $Revision: 1.20 $
+* Checkin $Date: 2003/11/10 17:13:37 $
+* Revising $Author: achapman $
+*/
+#include <cstdlib>
+/* Environment: */
+#include "unwind_env.h"
+/* Language-independent unwinder declarations: */
+#include "unwinder.h"
+/* Define PR_DIAGNOSTICS for printed diagnostics from the personality routine */
+#ifdef PR_DIAGNOSTICS
+extern int printf(const char *, ...);
+#endif
+/* Forward decl: */
+extern _Unwind_Reason_Code __ARM_unwind_cpp_prcommon(_Unwind_State state,
+_Unwind_Control_Block *ucbp,
+_Unwind_Context *context,
+uint32_t idx);
+/* Personality routines - external entry points.
+* pr0: short unwind description, 16 bit EHT offsets.
+* pr1: long unwind description, 16 bit EHT offsets.
+* pr2: long unwind description, 32 bit EHT offsets.
+*/
+#ifdef pr0_c
+_Unwind_Reason_Code __aeabi_unwind_cpp_pr0(_Unwind_State state,
+_Unwind_Control_Block *ucbp,
+_Unwind_Context *context) {
+return __ARM_unwind_cpp_prcommon(state, ucbp, context, 0);
+}
+#endif
+#ifdef pr1_c
+_Unwind_Reason_Code __aeabi_unwind_cpp_pr1(_Unwind_State state,
+_Unwind_Control_Block *ucbp,
+_Unwind_Context *context) {
+return __ARM_unwind_cpp_prcommon(state, ucbp, context, 1);
+}
+#endif
+#ifdef pr2_c
+_Unwind_Reason_Code __aeabi_unwind_cpp_pr2(_Unwind_State state,
+_Unwind_Control_Block *ucbp,
+_Unwind_Context *context) {
+return __ARM_unwind_cpp_prcommon(state, ucbp, context, 2);
+}
+#endif
+/* The rest of the file deals with the common routine */
+#ifdef prcommon_c
+/* C++ exceptions ABI required here:
+* Declare protocol routines called by the personality routine.
+* These are weak references so that referencing them here is
+* insufficient to pull them into the image - they will only be
+* included if application code uses a __cxa routine.
+*/
+typedef unsigned char bool;
+static const bool false = 0;
+static const bool true = !false;
+typedef struct _ZSt9type_info type_info; /* This names C++ type_info type */
+WEAKDECL void __cxa_call_unexpected(_Unwind_Control_Block *ucbp);
+WEAKDECL bool __cxa_begin_cleanup(_Unwind_Control_Block *ucbp);
+WEAKDECL bool __cxa_type_match(_Unwind_Control_Block *ucbp,
+const type_info *rttip,
+void **matched_object);
+/* ----- Address manipulation: ----- */
+/* The following helper function is never called and is present simply
+* for ease of packaging. The constant word within is used by
+* ER_RO_offset_to_addr to compute the RO segment base.
+* The zero word named W is relocated relative to the base B of the
+* segment which includes it, hence B is recoverable at runtime by
+* computing &W - W.
+*/
+extern const uint32_t __ARM_unwind_cpp_ROSegBase_SelfOffset;
+__asm void __ARM_unwind_cpp_basehelper(void)
+{
+export __ARM_unwind_cpp_ROSegBase_SelfOffset;
+R_ARM_ROSEGREL32        EQU 39
+__ARM_unwind_cpp_ROSegBase_SelfOffset;
+dcd 0;
+__RELOC R_ARM_ROSEGREL32,__ARM_unwind_cpp_ROSegBase_SelfOffset;
+}
+#define ER_RO_SegBase ((uint32_t)&__ARM_unwind_cpp_ROSegBase_SelfOffset - \
+__ARM_unwind_cpp_ROSegBase_SelfOffset)
+/* And now the function used to convert segment-relative offsets
+* to absolute addresses.
+*/
+static __inline uint32_t ER_RO_offset_to_addr(uint32_t offset)
+{
+return offset + ER_RO_SegBase;
+}
+/* --------- VRS manipulation: --------- */
+#define R_SP 13
+#define R_LR 14
+#define R_PC 15
+static __inline uint32_t core_get(_Unwind_Context *context, uint32_t regno)
+{
+uint32_t val;
+/* This call is required to never fail if given a valid regno */
+_Unwind_VRS_Get(context, _UVRSC_CORE, regno, _UVRSD_UINT32, &val);
+return val;
+}
+static __inline void core_set(_Unwind_Context *context, uint32_t regno, uint32_t newval)
+{
+/* This call is required to never fail if given a valid regno */
+_Unwind_VRS_Set(context, _UVRSC_CORE, regno, _UVRSD_UINT32, &newval);
+}
+static __inline uint32_t count_to_mask(uint32_t count) {
+return (1 << count) - 1;
+}
+/* --------- Support for unwind instruction stream: --------- */
+#define CODE_FINISH (0xb0)
+typedef struct uwdata {
+uint32_t unwind_word;                  /* current word of unwind description */
+uint32_t *unwind_word_pointer;         /* ptr to next word */
+uint8_t unwind_word_bytes_remaining;   /* count of bytes left in current word */
+uint8_t unwind_words_remaining;        /* count of words left, at ptr onwards */
+} uwdata;
+static __inline uint8_t next_unwind_byte(uwdata *u) {
+uint8_t ub;
+if (u->unwind_word_bytes_remaining == 0) {  /* Load another word */
+if (u->unwind_words_remaining == 0) return CODE_FINISH; /* nothing left - yield NOP */
+u->unwind_words_remaining--;
+u->unwind_word = *(u->unwind_word_pointer++);
+u->unwind_word_bytes_remaining = 4;
+}
+u->unwind_word_bytes_remaining--;
+ub = (u->unwind_word & 0xff000000) >> 24;
+u->unwind_word <<= 8;
+return ub;
+}
+/* --------- Personality routines: --------- */
+/* The C++ Standard is silent on what is supposed to happen if an internal
+* inconsistency occurs during unwinding. In our design, we return to the
+* caller with _URC_FAILURE. During phase 1 this causes a return from the
+* language-independent unwinder to its caller (__cxa_throw or __cxa_rethrow)
+* which will then call terminate(). If an error occurs during phase 2, the
+* caller will call abort().
+*/
+/* Types to assist with reading EHT's */
+typedef struct {
+uint16_t length;
+uint16_t offset;
+} EHT16;
+typedef struct {
+uint32_t length;
+uint32_t offset;
+} EHT32;
+typedef uint32_t landingpad_t;
+typedef struct {
+landingpad_t landingpad;
+} EHT_cleanup_tail;
+typedef struct {
+landingpad_t landingpad;
+uint32_t rtti_offset;
+} EHT_catch_tail;
+typedef struct {
+uint32_t rtti_count;           /* table count (possibly 0) */
+uint32_t (rtti_offsets[1]);    /* variable length table, possibly followed by landing pad */
+} EHT_fnspec_tail;
+/* Macros: */
+/* Barrier cache: */
+/* Requirement imposed by C++ semantics module - match object in slot 0: */
+#define BARRIER_HANDLEROBJECT (0)
+/* Requirement imposed by C++ semantics module - function exception spec info */
+#define BARRIER_FNSPECCOUNT  (1)
+#define BARRIER_FNSPECBASE   (2)
+#define BARRIER_FNSPECSTRIDE (3)
+#define BARRIER_FNSPECARRAY  (4)
+/* Private use for us between phase 1 & 2: */
+#define BARRIER_EHTP (1)
+#define SAVE_PROPAGATION_BARRIER(UCB_PTR,VSP,EHTP,HANDLEROBJECT) \
+(UCB_PTR)->barrier_cache.sp = (VSP);    \
+(UCB_PTR)->barrier_cache.bitpattern[BARRIER_EHTP] = (uint32_t)(EHTP); \
+(UCB_PTR)->barrier_cache.bitpattern[BARRIER_HANDLEROBJECT] = (uint32_t)(HANDLEROBJECT);
+#define CHECK_FOR_PROPAGATION_BARRIER(UCB_PTR,VSP,EHTP) \
+((UCB_PTR)->barrier_cache.sp == (VSP) &&    \
+(UCB_PTR)->barrier_cache.bitpattern[BARRIER_EHTP] == (uint32_t)(EHTP))
+/* Cleanup cache: We only use one field */
+#define CLEANUP_EHTP (0)
+/* Special catch rtti values */
+#define CATCH_ALL               (0xffffffff)
+#define CATCH_ALL_AND_TERMINATE (0xfffffffe)
+/* Common personality routine: receives pr index as an argument.
+*
+* Note this implementation contains no explicit check against attempting to
+* unwind off the top of the stack. Instead it relies (in cooperation with
+* the language-independent unwinder) on there being a propagation barrier
+* somewhere on the stack, perhaps the caller to main being not
+* unwindable. An alternative would be to check for the stack pointer
+* addressing a stack limit symbol.
+*/
+_Unwind_Reason_Code __ARM_unwind_cpp_prcommon(_Unwind_State state,
+_Unwind_Control_Block *ucbp,
+_Unwind_Context *context,
+uint32_t idx)
+{
+_Unwind_EHT_Header *eht_startp;  /* EHT start pointer */
+uint8_t *ehtp; /* EHT pointer, incremented as required */
+/* Flag for fnspec violations in which the frame should be unwound before calling unexpected() */
+bool phase2_call_unexpected_after_unwind;
+/* Flag for whether we have loaded r15 (pc) with a return address while executing
+* unwind instructions.
+* Set this on any write to r15 while executing the unwind instructions.
+*/
+bool wrote_pc = false;
+/* Flag for whether we loaded r15 from r14 while executing the unwind instructions */
+bool wrote_pc_from_lr = false;
+uwdata ud;
+/* Mark all as well and extract the EHT pointer */
+eht_startp = ucbp->pr_cache.ehtp;
+#ifdef PR_DIAGNOSTICS
+printf("PR entered: state=%d, r15=0x%x, fnstart=0x%x\n",
+state, core_get(context, R_PC), ucbp->pr_cache.fnstart);
+#endif
+/* What are we supposed to do? */
+if (state != _US_VIRTUAL_UNWIND_FRAME &&
+state != _US_UNWIND_FRAME_STARTING &&
+state != _US_UNWIND_FRAME_RESUME) {
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_ENDING, _UAARG_ENDING_UNSPECIFIED);
+return _URC_FAILURE;
+}
+phase2_call_unexpected_after_unwind = false;
+/* Traverse the current EHT, if there is one.
+* The required behaviours are:
+* _US_VIRTUAL_UNWIND_FRAME: search for a propagation barrier in this frame.
+* otherwise look for the propagation barrier we found in phase 1,
+* performing cleanups on the way. In this case if state will be one of:
+*   _US_UNWIND_FRAME_STARTING  first time with this frame
+*   _US_UNWIND_FRAME_RESUME    not first time, we are part-way through the EHT.
+*/
+if ((ucbp->pr_cache.additional & 1) == 0) { /* EHT inline in index table? */
+/* No: thus there is a real EHT */
+if (state == _US_UNWIND_FRAME_RESUME) {
+/* Recover saved pointer to next EHT entry */
+ehtp = (uint8_t *)ucbp->cleanup_cache.bitpattern[CLEANUP_EHTP];
+#ifdef PR_DIAGNOSTICS
+printf("PR EHT recovered pointer 0x%x\n", (int)ehtp);
+#endif
+} else {
+/* Point at the first EHT entry.
+* For pr0, the unwind description is entirely within the header word.
+* For pr1 & pr2, an unwind description extension word count is
+* held in bits 16-23 of the header word.
+*/
+uint32_t unwind_extension_word_count = (idx == 0 ? 0 : ((*eht_startp) >> 16) & 0xff);
+ehtp = (uint8_t *)(eht_startp + 1 + unwind_extension_word_count);
+#ifdef PR_DIAGNOSTICS
+printf("PR EHT first entry at 0x%x\n", (int)ehtp);
+#endif
+}
+/* scan ... */
+while (1) {
+/* Extract 32 bit length and offset */
+uint32_t length;
+uint32_t offset;
+if (idx == 2) {
+/* 32 bit offsets */
+length = ((EHT32 *)ehtp)->length;
+if (length == 0) break; /* end of table */
+offset = ((EHT32 *)ehtp)->offset;
+ehtp += sizeof(EHT32);
+} else {
+/* 16 bit offsets */
+length = ((EHT16 *)ehtp)->length;
+if (length == 0) break; /* end of table */
+offset = ((EHT16 *)ehtp)->offset;
+ehtp += sizeof(EHT16);
+}
+#ifdef PR_DIAGNOSTICS
+printf("PR Got entry at 0x%x code=%d, length=0x%x, offset=0x%x\n",
+(int)(ehtp-4), ((offset & 1) << 1) | (length & 1),
+length & ~1, offset & ~1);
+#endif
+/* Dispatch on the kind of entry */
+switch (((offset & 1) << 1) | (length & 1)) {
+case 0: /* cleanup */
+if (state == _US_VIRTUAL_UNWIND_FRAME) {
+/* Not a propagation barrier - skip */
+} else {
+/* Phase 2: call the cleanup if the return address is in range */
+uint32_t padaddress;
+uint32_t rangestartaddr = ucbp->pr_cache.fnstart + offset;
+uint32_t rtn_addr = core_get(context, R_PC);
+if (rangestartaddr <= rtn_addr && rtn_addr < rangestartaddr + length) {
+/* It is in range. */
+landingpad_t landingpad = ((EHT_cleanup_tail *)ehtp)->landingpad;
+ehtp += sizeof(EHT_cleanup_tail);
+/* Dump state into the ECO so we resume correctly after the cleanup. */
+/* We simply save the address of the next EHT entry. */
+ucbp->cleanup_cache.bitpattern[CLEANUP_EHTP] = (uint32_t)ehtp;
+if (!__cxa_begin_cleanup(ucbp)) {
+/* Should be impossible, using ARM's library */
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_ENDING, _UAARG_ENDING_UNSPECIFIED);
+return _URC_FAILURE;
+}
+/* Set up the VRS to enter the landing pad. */
+padaddress = ER_RO_offset_to_addr(landingpad);
+core_set(context, R_PC, padaddress);
+#ifdef PR_DIAGNOSTICS
+printf("PR Got cleanup in range, cleanup addr=0x%x\n", core_get(context, R_PC));
+printf("PR Saving EHT pointer 0x%x\n", (int)ehtp);
+#endif
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_PADENTRY, padaddress);
+/* Exit requesting upload the VRS to the real machine. */
+return _URC_INSTALL_CONTEXT;
+}
+}
+/* Phase 1, or phase 2 and not in range */
+ehtp += sizeof(EHT_cleanup_tail);
+break;
+case 1: /* catch */
+{
+if (state == _US_VIRTUAL_UNWIND_FRAME) {
+/* In range, and with a matching type? */
+uint32_t rangestartaddr = ucbp->pr_cache.fnstart + offset;
+uint32_t rtn_addr = core_get(context, R_PC);
+void *matched_object;
+length -= 1;   /* length had low bit set - clear it */
+if (rangestartaddr <= rtn_addr && rtn_addr < rangestartaddr + length) {
+/* In range */
+uint32_t rtti_val = ((EHT_catch_tail *)ehtp)->rtti_offset;
+if (rtti_val == CATCH_ALL_AND_TERMINATE) {
+/* Always matches and causes propagation failure in phase 1 */
+#ifdef PR_DIAGNOSTICS
+printf("PR Got CATCH_ALL_AND_TERMINATE in phase 1\n");
+#endif
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_ENDING, _UAARG_ENDING_NOUNWIND);
+return _URC_FAILURE;
+}
+if ((rtti_val == CATCH_ALL && ((matched_object = ucbp + 1),1)) ||
+__cxa_type_match(ucbp,
+(type_info *)(rtti_val = ER_RO_offset_to_addr(rtti_val)),
+&matched_object)) {
+/* In range and matches.
+* Record the propagation barrier details for ease of detection in phase 2.
+* We save a pointer to the middle of the handler entry -
+* this is fine, so long as we are consistent about it.
+*/
+#ifdef PR_DIAGNOSTICS
+printf("PR Got barrier in phase 1\n");
+printf("PR Matched object address 0x%8.8x\n", matched_object);
+#endif
+SAVE_PROPAGATION_BARRIER(ucbp, core_get(context, R_SP), ehtp, matched_object);
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_BARRIERFOUND,
+ER_RO_offset_to_addr(((EHT_catch_tail *)ehtp)->landingpad));
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_CPP_TYPEINFO, rtti_val);
+return _URC_HANDLER_FOUND;
+}
+}
+/* Not in range or no type match - fall thru to carry on scanning the table */
+} else {
+/* Else this is phase 2: have we encountered the saved barrier? */
+if (CHECK_FOR_PROPAGATION_BARRIER(ucbp, core_get(context, R_SP), ehtp)) {
+/* Yes we have.
+* Set up the VRS to enter the landing pad,
+* and upload the VRS to the real machine.
+*/
+landingpad_t landingpad;
+uint32_t padaddress;
+#ifdef PR_DIAGNOSTICS
+printf("PR Got catch barrier in phase 2\n");
+#endif
+landingpad = ((EHT_catch_tail *)ehtp)->landingpad;
+padaddress = ER_RO_offset_to_addr(landingpad);
+core_set(context, R_PC, padaddress);
+core_set(context, 0, (uint32_t)ucbp);
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_PADENTRY, padaddress);
+/* Exit requesting upload the VRS to the real machine. */
+return _URC_INSTALL_CONTEXT;
+}
+}
+/* Else carry on scanning the table */
+ehtp += sizeof(EHT_catch_tail);
+break;
+}
+case 2: /* function exception specification (fnspec) */
+{
+uint32_t counter_word = ((EHT_fnspec_tail *)ehtp)->rtti_count;
+uint32_t rtti_count = counter_word & 0x7fffffff;   /* Extract offset count */
+if (state == _US_VIRTUAL_UNWIND_FRAME) {
+/* Phase 1 */
+/* In range? Offset had low bit set - clear it */
+uint32_t rangestartaddr = ucbp->pr_cache.fnstart + offset - 1;
+uint32_t rtn_addr = core_get(context, R_PC);
+if (rangestartaddr <= rtn_addr && rtn_addr < rangestartaddr + length) {
+/* See if any type matches */
+uint32_t *rttipp = &((EHT_fnspec_tail *)ehtp)->rtti_offsets[0];
+uint32_t i;
+for (i = 0; i < rtti_count; i++) {
+void *matched_object;
+if (__cxa_type_match(ucbp,
+(type_info *)ER_RO_offset_to_addr(*rttipp),
+&matched_object)) {
+#ifdef PR_DIAGNOSTICS
+printf("PR Fnspec matched in phase 1\n");
+#endif
+break;
+}
+rttipp++;
+}
+if (i == rtti_count) { /* NB case rtti_count==0 forces no match [for throw()] */
+/* No match - fnspec violation is a propagation barrier */
+#ifdef PR_DIAGNOSTICS
+printf("PR Got fnspec barrier in phase 1\n");
+#endif
+SAVE_PROPAGATION_BARRIER(ucbp, core_get(context, R_SP), ehtp, 0); /* save ptr to the count of types */
+/* Even if this is a fnspec with a landing pad, we always end up in
+* __cxa_call_unexpected so tell the debugger thats where we're going
+*/
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_BARRIERFOUND, &__cxa_call_unexpected);
+return _URC_HANDLER_FOUND;
+}
+} /* if (in range...) */
+/* Fall out of the 'if' to continue table scanning */
+} else {
+/* Else this is phase 2: have we encountered the saved barrier? */
+if (CHECK_FOR_PROPAGATION_BARRIER(ucbp, core_get(context, R_SP), ehtp)) {
+/* Yes we have. Fill in the UCB barrier_cache for entry to __cxa_call_unexpected */
+uint32_t *p = (uint32_t *)ehtp; /* ptr to rtti count */
+ucbp->barrier_cache.bitpattern[BARRIER_FNSPECCOUNT] = rtti_count;
+ucbp->barrier_cache.bitpattern[BARRIER_FNSPECBASE] = ER_RO_offset_to_addr(0); /* base address */
+ucbp->barrier_cache.bitpattern[BARRIER_FNSPECSTRIDE] = 4; /* stride */
+ucbp->barrier_cache.bitpattern[BARRIER_FNSPECARRAY]  = (uint32_t)(p + 1); /* address of rtti offset list */
+/* If this is a fnspec with an attached landing pad, we must enter
+* the pad immediately. Otherwise we need to unwind the frame before
+* calling __cxa_call_unexpected() so set a flag to make this happen.
+*/
+if (counter_word == rtti_count)
+phase2_call_unexpected_after_unwind = true; /* no pad, enter later */
+else { /* pad */
+landingpad_t landingpad;
+uint32_t padaddress;
+#ifdef PR_DIAGNOSTICS
+printf("PR Got fnspec barrier in phase 2 (immediate entry)\n");
+#endif
+ehtp += (sizeof(((EHT_fnspec_tail *)ehtp)->rtti_count) +
+sizeof(uint32_t) * rtti_count);  /* point at pad offset */
+landingpad = *(landingpad_t *)ehtp;
+padaddress = ER_RO_offset_to_addr(landingpad);
+core_set(context, 0, (uint32_t)ucbp);
+core_set(context, R_PC, padaddress);
+/* Even if this is a fnspec with a landing pad, in phase 1 we said we'd
+* end up in __cxa_call_unexpected so show the same thing now
+*/
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_PADENTRY, &__cxa_call_unexpected);
+return _URC_INSTALL_CONTEXT;
+}
+} /* endif (barrier match) */
+} /* endif (which phase) */
+/* Advance to the next item, remembering to skip the landing pad if present */
+ehtp += (sizeof(((EHT_fnspec_tail *)ehtp)->rtti_count) +
+sizeof(uint32_t) * rtti_count +
+(counter_word == rtti_count ? 0 : sizeof(landingpad_t)));
+break;
+}
+case 3: /* unallocated */
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_ENDING, _UAARG_ENDING_TABLECORRUPT);
+return _URC_FAILURE;
+} /* switch */
+} /* while (1) */
+#ifdef PR_DIAGNOSTICS
+printf("PR Reached end of EHT\n");
+#endif
+} /* if out-of-line EHT */
+/* Do a virtual unwind of this frame - load the first unwind bytes then loop.
+* Loop exit is by executing opcode CODE_FINISH.
+*/
+ud.unwind_word = *(uint32_t *)eht_startp;             /* first word */
+ud.unwind_word_pointer = (uint32_t *)eht_startp + 1;  /* ptr to extension words, if any */
+if (idx == 0) {                  /* short description */
+ud.unwind_words_remaining = 0; /* no further words */
+ud.unwind_word <<= 8;          /* 3 explicit unwind bytes in this word */
+ud.unwind_word_bytes_remaining = 3;
+} else {                         /* long description: extension word count in bits 16-23 */
+ud.unwind_words_remaining = ((ud.unwind_word) >> 16) & 0xff;
+ud.unwind_word <<= 16;         /* 2 explicit unwind bytes in this word */
+ud.unwind_word_bytes_remaining = 2;
+}
+#ifdef PR_DIAGNOSTICS
+/*  debug_print_vrs(context); */
+#endif
+while (1) {
+uint8_t ub = next_unwind_byte(&ud);
+#ifdef PR_DIAGNOSTICS
+printf("PR Unwind byte 0x%x\n", ub);
+#endif
+/* decode and execute the current byte ... */
+if (ub == CODE_FINISH) { /* finished unwinding */
+if (!wrote_pc) {
+uint32_t lr;
+_Unwind_VRS_Get(context, _UVRSC_CORE, R_LR, _UVRSD_UINT32, &lr);
+core_set(context, R_PC, lr);
+wrote_pc_from_lr = true;
+}
+#ifdef PR_DIAGNOSTICS
+{
+uint32_t nextpc;
+_Unwind_VRS_Get(context, _UVRSC_CORE, R_PC, _UVRSD_UINT32, &nextpc);
+printf("PR Next PC is  0x%x\n", nextpc);
+}
+#endif
+break;
+}
+if (ub <= 0x3f) { /* 00nnnnnn: vsp += (nnnnnn << 2) + 4 */
+uint32_t increment = ((ub & 0x3f) << 2) + 4;
+core_set(context, R_SP, core_get(context, R_SP) + increment);
+continue;
+}
+if (ub <= 0x7f) { /* 01xxxxxx: vsp -= (xxxxxx << 2) + 4 */
+uint32_t decrement = ((ub & 0x3f) << 2) + 4;
+core_set(context, R_SP, core_get(context, R_SP) - decrement);
+continue;
+}
+if (ub <= 0x8f) { /* 100000000 00000000: refuse, 1000rrrr rrrrrrrr: pop integer regs */
+uint32_t mask = (ub & 0xf) << 12;
+ub = next_unwind_byte(&ud);
+mask |= ub << 4;
+if (mask == 0) { /* 10000000 00000000 refuse to unwind */
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_ENDING, _UAARG_ENDING_NOUNWIND);
+return _URC_FAILURE;
+}
+if (_Unwind_VRS_Pop(context, _UVRSC_CORE, mask, _UVRSD_UINT32) != _UVRSR_OK) {
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_ENDING, _UAARG_ENDING_VRSFAILED);
+return _URC_FAILURE;
+}
+if (mask & (1 << R_PC)) wrote_pc = true;
+continue;
+}
+if (ub <= 0x9f) { /* 1001nnnn: vsp = r[nnnn] if not 13,15 */
+uint8_t regno = ub & 0xf;
+if (regno == 13 || regno == R_PC) {  /* reserved */
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_ENDING, _UAARG_ENDING_CPP_BADOPCODE);
+return _URC_FAILURE;
+}
+core_set(context, R_SP, core_get(context, regno));
+continue;
+}
+if (ub <= 0xaf) { /* 1010xnnn: pop r4-r[4+nnn], +r14 if x */
+uint32_t mask = count_to_mask((ub & 0x7) + 1) << 4;
+if (ub & 0x8) mask |= (1 << R_LR);
+if (_Unwind_VRS_Pop(context, _UVRSC_CORE, mask, _UVRSD_UINT32) != _UVRSR_OK) {
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_ENDING, _UAARG_ENDING_VRSFAILED);
+return _URC_FAILURE;
+}
+continue;
+}
+if (ub <= 0xb7) {
+/* if (ub == 0xb0) is CODE_FINISH, handled earlier */
+if (ub == 0xb1) { /* 10110001 0000iiii pop integer regs, others reserved */
+uint32_t mask = next_unwind_byte(&ud);
+if (mask == 0 || mask > 0xf) { /* reserved */
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_ENDING, _UAARG_ENDING_CPP_BADOPCODE);
+return _URC_FAILURE;
+}
+if (_Unwind_VRS_Pop(context, _UVRSC_CORE, mask, _UVRSD_UINT32) != _UVRSR_OK) {
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_ENDING, _UAARG_ENDING_VRSFAILED);
+return _URC_FAILURE;
+}
+continue;
+}
+if (ub == 0xb2) { /* 10110010 uleb128 : vsp += (uleb128 << 2) + 0x204 */
+uint32_t u = 0;
+uint32_t n = 0;
+/* decode */
+while (1) {
+ub = next_unwind_byte(&ud);
+u |= (ub & 0x7f) << n;
+if ((ub & 0x80) == 0) break;
+n += 7;
+}
+core_set(context, R_SP, core_get(context, R_SP) + (u << 2) + 0x204);
+continue;
+}
+if (ub == 0xb3) { /* 10110011: pop vfp */
+uint32_t discriminator = next_unwind_byte(&ud);
+discriminator = ((discriminator & 0xf0) << 12) | ((discriminator & 0x0f) + 1);
+if (_Unwind_VRS_Pop(context, _UVRSC_VFP, discriminator, _UVRSD_VFPX) != _UVRSR_OK) {
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_ENDING, _UAARG_ENDING_VRSFAILED);
+return _URC_FAILURE;
+}
+continue;
+}
+{ /* 101101nn: pop fpa */
+uint32_t discriminator = 0x40000 | ((ub & 0x3) + 1);
+if (_Unwind_VRS_Pop(context, _UVRSC_FPA, discriminator, _UVRSD_FPAX) != _UVRSR_OK) {
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_ENDING, _UAARG_ENDING_VRSFAILED);
+return _URC_FAILURE;
+}
+continue;
+}
+} /* if (ub <= 0xb7) ... */
+if (ub <= 0xbf) { /* 10111nnn: pop vfp */
+uint32_t discriminator = 0x80000 | ((ub & 0x7) + 1);
+if (_Unwind_VRS_Pop(context, _UVRSC_VFP, discriminator, _UVRSD_VFPX) != _UVRSR_OK) {
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_ENDING, _UAARG_ENDING_VRSFAILED);
+return _URC_FAILURE;
+}
+continue;
+}
+if (ub <= 0xc7) {
+if (ub == 0xc7) { /* 11000111: WMMX C regs */
+uint32_t mask = next_unwind_byte(&ud);
+if (mask == 0 || mask > 0xf) { /* reserved */
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_ENDING, _UAARG_ENDING_CPP_BADOPCODE);
+return _URC_FAILURE;
+}
+if (_Unwind_VRS_Pop(context, _UVRSC_WMMXC, mask, _UVRSD_UINT32) != _UVRSR_OK) {
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_ENDING, _UAARG_ENDING_VRSFAILED);
+return _URC_FAILURE;
+}
+continue;
+} else if (ub == 0xc6) { /* 11000110: WMMX D regs */
+uint32_t discriminator = next_unwind_byte(&ud);
+discriminator = ((discriminator & 0xf0) << 4) | ((discriminator & 0x0f) + 1);
+if (_Unwind_VRS_Pop(context, _UVRSC_WMMXD, discriminator, _UVRSD_UINT64) != _UVRSR_OK) {
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_ENDING, _UAARG_ENDING_VRSFAILED);
+return _URC_FAILURE;
+}
+continue;
+} else {
+/* 11000nnn (nnn != 6, 7): WMMX D regs */
+uint32_t discriminator = 0xa00 | ((ub & 0x7) + 1);
+if (_Unwind_VRS_Pop(context, _UVRSC_WMMXD, discriminator, _UVRSD_UINT64) != _UVRSR_OK) {
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_ENDING, _UAARG_ENDING_VRSFAILED);
+return _URC_FAILURE;
+}
+continue;
+}
+} /* if (ub <= 0xc7) ... */
+if (ub == 0xc8) { /* 11001000: pop fpa */
+uint32_t discriminator = next_unwind_byte(&ud);
+discriminator = ((discriminator & 0x70) << 12) | ((discriminator & 0x03) + 1);
+if (_Unwind_VRS_Pop(context, _UVRSC_FPA, discriminator, _UVRSD_FPAX) != _UVRSR_OK) {
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_ENDING, _UAARG_ENDING_VRSFAILED);
+return _URC_FAILURE;
+}
+continue;
+}
+/* and in fact everything else is currently reserved or spare */
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_ENDING, _UAARG_ENDING_CPP_BADOPCODE);
+return _URC_FAILURE;
+}
+#ifdef PR_DIAGNOSTICS
+/* debug_print_vrs(context); */
+#endif
+/* The VRS has now been updated to reflect the virtual unwind.
+* If we are dealing with an unmatched fnspec, pop intervening frames
+* and call unexpected(). Else return to our caller with an
+* indication to continue unwinding.
+*/
+if (phase2_call_unexpected_after_unwind) {
+/* Set up the VRS to enter __cxa_call_unexpected,
+* and upload the VRS to the real machine.
+* The barrier_cache was initialised earlier.
+*/
+#ifdef PR_DIAGNOSTICS
+printf("PR Got fnspec barrier in phase 2 (unwinding completed)\n");
+#endif
+core_set(context, 0, (uint32_t)ucbp);
+if (!wrote_pc_from_lr) {
+uint32_t pc;
+/* Move the return address to lr to simulate a call */
+_Unwind_VRS_Get(context, _UVRSC_CORE, R_PC, _UVRSD_UINT32, &pc);
+core_set(context, R_LR, pc);
+}
+core_set(context, R_PC, (uint32_t)&__cxa_call_unexpected);
+DEBUGGER_BOTTLENECK(ucbp, _UASUBSYS_CPP, _UAACT_PADENTRY, &__cxa_call_unexpected);
+return _URC_INSTALL_CONTEXT;
+}
+/* Else continue with next frame */
+return _URC_CONTINUE_UNWIND;
+}
+#endif
+/* end ifdef prcommon_c */