target/arm/tcg/tlb_helper.c - qemu - Git at Google

 /*
  * ARM TLB (Translation lookaside buffer) helpers.
  *
  * This code is licensed under the GNU GPL v2 or later.
  *
  * SPDX-License-Identifier: GPL-2.0-or-later
  */
 #include "qemu/osdep.h"
 #include "cpu.h"
 #include "internals.h"
 #include "cpu-features.h"
 #include "exec/exec-all.h"
 #include "exec/helper-proto.h"


 /*
  * Returns true if the stage 1 translation regime is using LPAE format page
  * tables. Used when raising alignment exceptions, whose FSR changes depending
  * on whether the long or short descriptor format is in use.
  */
 bool arm_s1_regime_using_lpae_format(CPUARMState *env, ARMMMUIdx mmu_idx)
 {
     mmu_idx = stage_1_mmu_idx(mmu_idx);
     return regime_using_lpae_format(env, mmu_idx);
 }

 static inline uint32_t merge_syn_data_abort(uint32_t template_syn,
                                             ARMMMUFaultInfo *fi,
                                             unsigned int target_el,
                                             bool same_el, bool is_write,
                                             int fsc)
 {
     uint32_t syn;

     /*
      * ISV is only set for stage-2 data aborts routed to EL2 and
      * never for stage-1 page table walks faulting on stage 2
      * or for stage-1 faults.
      *
      * Furthermore, ISV is only set for certain kinds of load/stores.
      * If the template syndrome does not have ISV set, we should leave
      * it cleared.
      *
      * See ARMv8 specs, D7-1974:
      * ISS encoding for an exception from a Data Abort, the
      * ISV field.
      *
      * TODO: FEAT_LS64/FEAT_LS64_V/FEAT_SL64_ACCDATA: Translation,
      * Access Flag, and Permission faults caused by LD64B, ST64B,
      * ST64BV, or ST64BV0 insns report syndrome info even for stage-1
      * faults and regardless of the target EL.
      */
     if (template_syn & ARM_EL_VNCR) {
         /*
          * FEAT_NV2 faults on accesses via VNCR_EL2 are a special case:
          * they are always reported as "same EL", even though we are going
          * from EL1 to EL2.
          */
         assert(!fi->stage2);
         syn = syn_data_abort_vncr(fi->ea, is_write, fsc);
     } else if (!(template_syn & ARM_EL_ISV) || target_el != 2
         || fi->s1ptw || !fi->stage2) {
         syn = syn_data_abort_no_iss(same_el, 0,
                                     fi->ea, 0, fi->s1ptw, is_write, fsc);
     } else {
         /*
          * Fields: IL, ISV, SAS, SSE, SRT, SF and AR come from the template
          * syndrome created at translation time.
          * Now we create the runtime syndrome with the remaining fields.
          */
         syn = syn_data_abort_with_iss(same_el,
                                       0, 0, 0, 0, 0,
                                       fi->ea, 0, fi->s1ptw, is_write, fsc,
                                       true);
         /* Merge the runtime syndrome with the template syndrome.  */
         syn |= template_syn;
     }
     return syn;
 }

 static uint32_t compute_fsr_fsc(CPUARMState *env, ARMMMUFaultInfo *fi,
                                 int target_el, int mmu_idx, uint32_t *ret_fsc)
 {
     ARMMMUIdx arm_mmu_idx = core_to_arm_mmu_idx(env, mmu_idx);
     uint32_t fsr, fsc;

     /*
      * For M-profile there is no guest-facing FSR. We compute a
      * short-form value for env->exception.fsr which we will then
      * examine in arm_v7m_cpu_do_interrupt(). In theory we could
      * use the LPAE format instead as long as both bits of code agree
      * (and arm_fi_to_lfsc() handled the M-profile specific
      * ARMFault_QEMU_NSCExec and ARMFault_QEMU_SFault cases).
      */
     if (!arm_feature(env, ARM_FEATURE_M) &&
         (target_el == 2 || arm_el_is_aa64(env, target_el) ||
          arm_s1_regime_using_lpae_format(env, arm_mmu_idx))) {
         /*
          * LPAE format fault status register : bottom 6 bits are
          * status code in the same form as needed for syndrome
          */
         fsr = arm_fi_to_lfsc(fi);
         fsc = extract32(fsr, 0, 6);
     } else {
         fsr = arm_fi_to_sfsc(fi);
         /*
          * Short format FSR : this fault will never actually be reported
          * to an EL that uses a syndrome register. Use a (currently)
          * reserved FSR code in case the constructed syndrome does leak
          * into the guest somehow.
          */
         fsc = 0x3f;
     }

     *ret_fsc = fsc;
     return fsr;
 }

 static bool report_as_gpc_exception(ARMCPU *cpu, int current_el,
                                     ARMMMUFaultInfo *fi)
 {
     bool ret;

     switch (fi->gpcf) {
     case GPCF_None:
         return false;
     case GPCF_AddressSize:
     case GPCF_Walk:
     case GPCF_EABT:
         /* R_PYTGX: GPT faults are reported as GPC. */
         ret = true;
         break;
     case GPCF_Fail:
         /*
          * R_BLYPM: A GPF at EL3 is reported as insn or data abort.
          * R_VBZMW, R_LXHQR: A GPF at EL[0-2] is reported as a GPC
          * if SCR_EL3.GPF is set, otherwise an insn or data abort.
          */
         ret = (cpu->env.cp15.scr_el3 & SCR_GPF) && current_el != 3;
         break;
     default:
         g_assert_not_reached();
     }

     assert(cpu_isar_feature(aa64_rme, cpu));
     assert(fi->type == ARMFault_GPCFOnWalk ||
            fi->type == ARMFault_GPCFOnOutput);
     if (fi->gpcf == GPCF_AddressSize) {
         assert(fi->level == 0);
     } else {
         assert(fi->level >= 0 && fi->level <= 1);
     }

     return ret;
 }

 static unsigned encode_gpcsc(ARMMMUFaultInfo *fi)
 {
     static uint8_t const gpcsc[] = {
         [GPCF_AddressSize] = 0b000000,
         [GPCF_Walk]        = 0b000100,
         [GPCF_Fail]        = 0b001100,
         [GPCF_EABT]        = 0b010100,
     };

     /* Note that we've validated fi->gpcf and fi->level above. */
     return gpcsc[fi->gpcf] | fi->level;
 }

 static G_NORETURN
 void arm_deliver_fault(ARMCPU *cpu, vaddr addr,
                        MMUAccessType access_type,
                        int mmu_idx, ARMMMUFaultInfo *fi)
 {
     CPUARMState *env = &cpu->env;
     int target_el = exception_target_el(env);
     int current_el = arm_current_el(env);
     bool same_el;
     uint32_t syn, exc, fsr, fsc;
     /*
      * We know this must be a data or insn abort, and that
      * env->exception.syndrome contains the template syndrome set
      * up at translate time. So we can check only the VNCR bit
      * (and indeed syndrome does not have the EC field in it,
      * because we masked that out in disas_set_insn_syndrome())
      */
     bool is_vncr = (access_type != MMU_INST_FETCH) &&
         (env->exception.syndrome & ARM_EL_VNCR);

     if (is_vncr) {
         /* FEAT_NV2 faults on accesses via VNCR_EL2 go to EL2 */
         target_el = 2;
     }

     if (report_as_gpc_exception(cpu, current_el, fi)) {
         target_el = 3;

         fsr = compute_fsr_fsc(env, fi, target_el, mmu_idx, &fsc);

         syn = syn_gpc(fi->stage2 && fi->type == ARMFault_GPCFOnWalk,
                       access_type == MMU_INST_FETCH,
                       encode_gpcsc(fi), is_vncr,
                       0, fi->s1ptw,
                       access_type == MMU_DATA_STORE, fsc);

         env->cp15.mfar_el3 = fi->paddr;
         switch (fi->paddr_space) {
         case ARMSS_Secure:
             break;
         case ARMSS_NonSecure:
             env->cp15.mfar_el3 |= R_MFAR_NS_MASK;
             break;
         case ARMSS_Root:
             env->cp15.mfar_el3 |= R_MFAR_NSE_MASK;
             break;
         case ARMSS_Realm:
             env->cp15.mfar_el3 |= R_MFAR_NSE_MASK | R_MFAR_NS_MASK;
             break;
         default:
             g_assert_not_reached();
         }

         exc = EXCP_GPC;
         goto do_raise;
     }

     /* If SCR_EL3.GPF is unset, GPF may still be routed to EL2. */
     if (fi->gpcf == GPCF_Fail && target_el < 2) {
         if (arm_hcr_el2_eff(env) & HCR_GPF) {
             target_el = 2;
         }
     }

     if (fi->stage2) {
         target_el = 2;
         env->cp15.hpfar_el2 = extract64(fi->s2addr, 12, 47) << 4;
         if (arm_is_secure_below_el3(env) && fi->s1ns) {
             env->cp15.hpfar_el2 |= HPFAR_NS;
         }
     }

     same_el = current_el == target_el;
     fsr = compute_fsr_fsc(env, fi, target_el, mmu_idx, &fsc);

     if (access_type == MMU_INST_FETCH) {
         syn = syn_insn_abort(same_el, fi->ea, fi->s1ptw, fsc);
         exc = EXCP_PREFETCH_ABORT;
     } else {
         syn = merge_syn_data_abort(env->exception.syndrome, fi, target_el,
                                    same_el, access_type == MMU_DATA_STORE,
                                    fsc);
         if (access_type == MMU_DATA_STORE
             && arm_feature(env, ARM_FEATURE_V6)) {
             fsr |= (1 << 11);
         }
         exc = EXCP_DATA_ABORT;
     }

  do_raise:
     env->exception.vaddress = addr;
     env->exception.fsr = fsr;
     raise_exception(env, exc, syn, target_el);
 }

 /* Raise a data fault alignment exception for the specified virtual address */
 void arm_cpu_do_unaligned_access(CPUState *cs, vaddr vaddr,
                                  MMUAccessType access_type,
                                  int mmu_idx, uintptr_t retaddr)
 {
     ARMCPU *cpu = ARM_CPU(cs);
     ARMMMUFaultInfo fi = {};

     /* now we have a real cpu fault */
     cpu_restore_state(cs, retaddr);

     fi.type = ARMFault_Alignment;
     arm_deliver_fault(cpu, vaddr, access_type, mmu_idx, &fi);
 }

 void helper_exception_pc_alignment(CPUARMState *env, target_ulong pc)
 {
     ARMMMUFaultInfo fi = { .type = ARMFault_Alignment };
     int target_el = exception_target_el(env);
     int mmu_idx = arm_env_mmu_index(env);
     uint32_t fsc;

     env->exception.vaddress = pc;

     /*
      * Note that the fsc is not applicable to this exception,
      * since any syndrome is pcalignment not insn_abort.
      */
     env->exception.fsr = compute_fsr_fsc(env, &fi, target_el, mmu_idx, &fsc);
     raise_exception(env, EXCP_PREFETCH_ABORT, syn_pcalignment(), target_el);
 }

 #if !defined(CONFIG_USER_ONLY)

 /*
  * arm_cpu_do_transaction_failed: handle a memory system error response
  * (eg "no device/memory present at address") by raising an external abort
  * exception
  */
 void arm_cpu_do_transaction_failed(CPUState *cs, hwaddr physaddr,
                                    vaddr addr, unsigned size,
                                    MMUAccessType access_type,
                                    int mmu_idx, MemTxAttrs attrs,
                                    MemTxResult response, uintptr_t retaddr)
 {
     ARMCPU *cpu = ARM_CPU(cs);
     ARMMMUFaultInfo fi = {};

     /* now we have a real cpu fault */
     cpu_restore_state(cs, retaddr);

     fi.ea = arm_extabort_type(response);
     fi.type = ARMFault_SyncExternal;
     arm_deliver_fault(cpu, addr, access_type, mmu_idx, &fi);
 }

 bool arm_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
                       MMUAccessType access_type, int mmu_idx,
                       bool probe, uintptr_t retaddr)
 {
     ARMCPU *cpu = ARM_CPU(cs);
     GetPhysAddrResult res = {};
     ARMMMUFaultInfo local_fi, *fi;
     int ret;

     /*
      * Allow S1_ptw_translate to see any fault generated here.
      * Since this may recurse, read and clear.
      */
     fi = cpu->env.tlb_fi;
     if (fi) {
         cpu->env.tlb_fi = NULL;
     } else {
         fi = memset(&local_fi, 0, sizeof(local_fi));
     }

     /*
      * Walk the page table and (if the mapping exists) add the page
      * to the TLB.  On success, return true.  Otherwise, if probing,
      * return false.  Otherwise populate fsr with ARM DFSR/IFSR fault
      * register format, and signal the fault.
      */
     ret = get_phys_addr(&cpu->env, address, access_type,
                         core_to_arm_mmu_idx(&cpu->env, mmu_idx),
                         &res, fi);
     if (likely(!ret)) {
         /*
          * Map a single [sub]page. Regions smaller than our declared
          * target page size are handled specially, so for those we
          * pass in the exact addresses.
          */
         if (res.f.lg_page_size >= TARGET_PAGE_BITS) {
             res.f.phys_addr &= TARGET_PAGE_MASK;
             address &= TARGET_PAGE_MASK;
         }

         res.f.extra.arm.pte_attrs = res.cacheattrs.attrs;
         res.f.extra.arm.shareability = res.cacheattrs.shareability;

         tlb_set_page_full(cs, mmu_idx, address, &res.f);
         return true;
     } else if (probe) {
         return false;
     } else {
         /* now we have a real cpu fault */
         cpu_restore_state(cs, retaddr);
         arm_deliver_fault(cpu, address, access_type, mmu_idx, fi);
     }
 }
 #else
 void arm_cpu_record_sigsegv(CPUState *cs, vaddr addr,
                             MMUAccessType access_type,
                             bool maperr, uintptr_t ra)
 {
     ARMMMUFaultInfo fi = {
         .type = maperr ? ARMFault_Translation : ARMFault_Permission,
         .level = 3,
     };
     ARMCPU *cpu = ARM_CPU(cs);

     /*
      * We report both ESR and FAR to signal handlers.
      * For now, it's easiest to deliver the fault normally.
      */
     cpu_restore_state(cs, ra);
     arm_deliver_fault(cpu, addr, access_type, MMU_USER_IDX, &fi);
 }

 void arm_cpu_record_sigbus(CPUState *cs, vaddr addr,
                            MMUAccessType access_type, uintptr_t ra)
 {
     arm_cpu_do_unaligned_access(cs, addr, access_type, MMU_USER_IDX, ra);
 }
 #endif /* !defined(CONFIG_USER_ONLY) */
	/*
	* ARM TLB (Translation lookaside buffer) helpers.
	*
	* This code is licensed under the GNU GPL v2 or later.
	*
	* SPDX-License-Identifier: GPL-2.0-or-later
	*/
	#include "qemu/osdep.h"
	#include "cpu.h"
	#include "internals.h"
	#include "cpu-features.h"
	#include "exec/exec-all.h"
	#include "exec/helper-proto.h"


	/*
	* Returns true if the stage 1 translation regime is using LPAE format page
	* tables. Used when raising alignment exceptions, whose FSR changes depending
	* on whether the long or short descriptor format is in use.
	*/
	bool arm_s1_regime_using_lpae_format(CPUARMState *env, ARMMMUIdx mmu_idx)
	{
	mmu_idx = stage_1_mmu_idx(mmu_idx);
	return regime_using_lpae_format(env, mmu_idx);
	}

	static inline uint32_t merge_syn_data_abort(uint32_t template_syn,
	ARMMMUFaultInfo *fi,
	unsigned int target_el,
	bool same_el, bool is_write,
	int fsc)
	{
	uint32_t syn;

	/*
	* ISV is only set for stage-2 data aborts routed to EL2 and
	* never for stage-1 page table walks faulting on stage 2
	* or for stage-1 faults.
	*
	* Furthermore, ISV is only set for certain kinds of load/stores.
	* If the template syndrome does not have ISV set, we should leave
	* it cleared.
	*
	* See ARMv8 specs, D7-1974:
	* ISS encoding for an exception from a Data Abort, the
	* ISV field.
	*
	* TODO: FEAT_LS64/FEAT_LS64_V/FEAT_SL64_ACCDATA: Translation,
	* Access Flag, and Permission faults caused by LD64B, ST64B,
	* ST64BV, or ST64BV0 insns report syndrome info even for stage-1
	* faults and regardless of the target EL.
	*/
	if (template_syn & ARM_EL_VNCR) {
	/*
	* FEAT_NV2 faults on accesses via VNCR_EL2 are a special case:
	* they are always reported as "same EL", even though we are going
	* from EL1 to EL2.
	*/
	assert(!fi->stage2);
	syn = syn_data_abort_vncr(fi->ea, is_write, fsc);
	} else if (!(template_syn & ARM_EL_ISV) \|\| target_el != 2
	\|\| fi->s1ptw \|\| !fi->stage2) {
	syn = syn_data_abort_no_iss(same_el, 0,
	fi->ea, 0, fi->s1ptw, is_write, fsc);
	} else {
	/*
	* Fields: IL, ISV, SAS, SSE, SRT, SF and AR come from the template
	* syndrome created at translation time.
	* Now we create the runtime syndrome with the remaining fields.
	*/
	syn = syn_data_abort_with_iss(same_el,
	0, 0, 0, 0, 0,
	fi->ea, 0, fi->s1ptw, is_write, fsc,
	true);
	/* Merge the runtime syndrome with the template syndrome. */
	syn \|= template_syn;
	}
	return syn;
	}

	static uint32_t compute_fsr_fsc(CPUARMState env, ARMMMUFaultInfo fi,
	int target_el, int mmu_idx, uint32_t *ret_fsc)
	{
	ARMMMUIdx arm_mmu_idx = core_to_arm_mmu_idx(env, mmu_idx);
	uint32_t fsr, fsc;

	/*
	* For M-profile there is no guest-facing FSR. We compute a
	* short-form value for env->exception.fsr which we will then
	* examine in arm_v7m_cpu_do_interrupt(). In theory we could
	* use the LPAE format instead as long as both bits of code agree
	* (and arm_fi_to_lfsc() handled the M-profile specific
	* ARMFault_QEMU_NSCExec and ARMFault_QEMU_SFault cases).
	*/
	if (!arm_feature(env, ARM_FEATURE_M) &&
	(target_el == 2 \|\| arm_el_is_aa64(env, target_el) \|\|
	arm_s1_regime_using_lpae_format(env, arm_mmu_idx))) {
	/*
	* LPAE format fault status register : bottom 6 bits are
	* status code in the same form as needed for syndrome
	*/
	fsr = arm_fi_to_lfsc(fi);
	fsc = extract32(fsr, 0, 6);
	} else {
	fsr = arm_fi_to_sfsc(fi);
	/*
	* Short format FSR : this fault will never actually be reported
	* to an EL that uses a syndrome register. Use a (currently)
	* reserved FSR code in case the constructed syndrome does leak
	* into the guest somehow.
	*/
	fsc = 0x3f;
	}

	*ret_fsc = fsc;
	return fsr;
	}

	static bool report_as_gpc_exception(ARMCPU *cpu, int current_el,
	ARMMMUFaultInfo *fi)
	{
	bool ret;

	switch (fi->gpcf) {
	case GPCF_None:
	return false;
	case GPCF_AddressSize:
	case GPCF_Walk:
	case GPCF_EABT:
	/* R_PYTGX: GPT faults are reported as GPC. */
	ret = true;
	break;
	case GPCF_Fail:
	/*
	* R_BLYPM: A GPF at EL3 is reported as insn or data abort.
	* R_VBZMW, R_LXHQR: A GPF at EL[0-2] is reported as a GPC
	* if SCR_EL3.GPF is set, otherwise an insn or data abort.
	*/
	ret = (cpu->env.cp15.scr_el3 & SCR_GPF) && current_el != 3;
	break;
	default:
	g_assert_not_reached();
	}

	assert(cpu_isar_feature(aa64_rme, cpu));
	assert(fi->type == ARMFault_GPCFOnWalk \|\|
	fi->type == ARMFault_GPCFOnOutput);
	if (fi->gpcf == GPCF_AddressSize) {
	assert(fi->level == 0);
	} else {
	assert(fi->level >= 0 && fi->level <= 1);
	}

	return ret;
	}

	static unsigned encode_gpcsc(ARMMMUFaultInfo *fi)
	{
	static uint8_t const gpcsc[] = {
	[GPCF_AddressSize] = 0b000000,
	[GPCF_Walk] = 0b000100,
	[GPCF_Fail] = 0b001100,
	[GPCF_EABT] = 0b010100,
	};

	/* Note that we've validated fi->gpcf and fi->level above. */
	return gpcsc[fi->gpcf] \| fi->level;
	}

	static G_NORETURN
	void arm_deliver_fault(ARMCPU *cpu, vaddr addr,
	MMUAccessType access_type,
	int mmu_idx, ARMMMUFaultInfo *fi)
	{
	CPUARMState *env = &cpu->env;
	int target_el = exception_target_el(env);
	int current_el = arm_current_el(env);
	bool same_el;
	uint32_t syn, exc, fsr, fsc;
	/*
	* We know this must be a data or insn abort, and that
	* env->exception.syndrome contains the template syndrome set
	* up at translate time. So we can check only the VNCR bit
	* (and indeed syndrome does not have the EC field in it,
	* because we masked that out in disas_set_insn_syndrome())
	*/
	bool is_vncr = (access_type != MMU_INST_FETCH) &&
	(env->exception.syndrome & ARM_EL_VNCR);

	if (is_vncr) {
	/* FEAT_NV2 faults on accesses via VNCR_EL2 go to EL2 */
	target_el = 2;
	}

	if (report_as_gpc_exception(cpu, current_el, fi)) {
	target_el = 3;

	fsr = compute_fsr_fsc(env, fi, target_el, mmu_idx, &fsc);

	syn = syn_gpc(fi->stage2 && fi->type == ARMFault_GPCFOnWalk,
	access_type == MMU_INST_FETCH,
	encode_gpcsc(fi), is_vncr,
	0, fi->s1ptw,
	access_type == MMU_DATA_STORE, fsc);

	env->cp15.mfar_el3 = fi->paddr;
	switch (fi->paddr_space) {
	case ARMSS_Secure:
	break;
	case ARMSS_NonSecure:
	env->cp15.mfar_el3 \|= R_MFAR_NS_MASK;
	break;
	case ARMSS_Root:
	env->cp15.mfar_el3 \|= R_MFAR_NSE_MASK;
	break;
	case ARMSS_Realm:
	env->cp15.mfar_el3 \|= R_MFAR_NSE_MASK \| R_MFAR_NS_MASK;
	break;
	default:
	g_assert_not_reached();
	}

	exc = EXCP_GPC;
	goto do_raise;
	}

	/* If SCR_EL3.GPF is unset, GPF may still be routed to EL2. */
	if (fi->gpcf == GPCF_Fail && target_el < 2) {
	if (arm_hcr_el2_eff(env) & HCR_GPF) {
	target_el = 2;
	}
	}

	if (fi->stage2) {
	target_el = 2;
	env->cp15.hpfar_el2 = extract64(fi->s2addr, 12, 47) << 4;
	if (arm_is_secure_below_el3(env) && fi->s1ns) {
	env->cp15.hpfar_el2 \|= HPFAR_NS;
	}
	}

	same_el = current_el == target_el;
	fsr = compute_fsr_fsc(env, fi, target_el, mmu_idx, &fsc);

	if (access_type == MMU_INST_FETCH) {
	syn = syn_insn_abort(same_el, fi->ea, fi->s1ptw, fsc);
	exc = EXCP_PREFETCH_ABORT;
	} else {
	syn = merge_syn_data_abort(env->exception.syndrome, fi, target_el,
	same_el, access_type == MMU_DATA_STORE,
	fsc);
	if (access_type == MMU_DATA_STORE
	&& arm_feature(env, ARM_FEATURE_V6)) {
	fsr \|= (1 << 11);
	}
	exc = EXCP_DATA_ABORT;
	}

	do_raise:
	env->exception.vaddress = addr;
	env->exception.fsr = fsr;
	raise_exception(env, exc, syn, target_el);
	}

	/* Raise a data fault alignment exception for the specified virtual address */
	void arm_cpu_do_unaligned_access(CPUState *cs, vaddr vaddr,
	MMUAccessType access_type,
	int mmu_idx, uintptr_t retaddr)
	{
	ARMCPU *cpu = ARM_CPU(cs);
	ARMMMUFaultInfo fi = {};

	/* now we have a real cpu fault */
	cpu_restore_state(cs, retaddr);

	fi.type = ARMFault_Alignment;
	arm_deliver_fault(cpu, vaddr, access_type, mmu_idx, &fi);
	}

	void helper_exception_pc_alignment(CPUARMState *env, target_ulong pc)
	{
	ARMMMUFaultInfo fi = { .type = ARMFault_Alignment };
	int target_el = exception_target_el(env);
	int mmu_idx = arm_env_mmu_index(env);
	uint32_t fsc;

	env->exception.vaddress = pc;

	/*
	* Note that the fsc is not applicable to this exception,
	* since any syndrome is pcalignment not insn_abort.
	*/
	env->exception.fsr = compute_fsr_fsc(env, &fi, target_el, mmu_idx, &fsc);
	raise_exception(env, EXCP_PREFETCH_ABORT, syn_pcalignment(), target_el);
	}

	#if !defined(CONFIG_USER_ONLY)

	/*
	* arm_cpu_do_transaction_failed: handle a memory system error response
	* (eg "no device/memory present at address") by raising an external abort
	* exception
	*/
	void arm_cpu_do_transaction_failed(CPUState *cs, hwaddr physaddr,
	vaddr addr, unsigned size,
	MMUAccessType access_type,
	int mmu_idx, MemTxAttrs attrs,
	MemTxResult response, uintptr_t retaddr)
	{
	ARMCPU *cpu = ARM_CPU(cs);
	ARMMMUFaultInfo fi = {};

	/* now we have a real cpu fault */
	cpu_restore_state(cs, retaddr);

	fi.ea = arm_extabort_type(response);
	fi.type = ARMFault_SyncExternal;
	arm_deliver_fault(cpu, addr, access_type, mmu_idx, &fi);
	}

	bool arm_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
	MMUAccessType access_type, int mmu_idx,
	bool probe, uintptr_t retaddr)
	{
	ARMCPU *cpu = ARM_CPU(cs);
	GetPhysAddrResult res = {};
	ARMMMUFaultInfo local_fi, *fi;
	int ret;

	/*
	* Allow S1_ptw_translate to see any fault generated here.
	* Since this may recurse, read and clear.
	*/
	fi = cpu->env.tlb_fi;
	if (fi) {
	cpu->env.tlb_fi = NULL;
	} else {
	fi = memset(&local_fi, 0, sizeof(local_fi));
	}

	/*
	* Walk the page table and (if the mapping exists) add the page
	* to the TLB. On success, return true. Otherwise, if probing,
	* return false. Otherwise populate fsr with ARM DFSR/IFSR fault
	* register format, and signal the fault.
	*/
	ret = get_phys_addr(&cpu->env, address, access_type,
	core_to_arm_mmu_idx(&cpu->env, mmu_idx),
	&res, fi);
	if (likely(!ret)) {
	/*
	* Map a single [sub]page. Regions smaller than our declared
	* target page size are handled specially, so for those we
	* pass in the exact addresses.
	*/
	if (res.f.lg_page_size >= TARGET_PAGE_BITS) {
	res.f.phys_addr &= TARGET_PAGE_MASK;
	address &= TARGET_PAGE_MASK;
	}

	res.f.extra.arm.pte_attrs = res.cacheattrs.attrs;
	res.f.extra.arm.shareability = res.cacheattrs.shareability;

	tlb_set_page_full(cs, mmu_idx, address, &res.f);
	return true;
	} else if (probe) {
	return false;
	} else {
	/* now we have a real cpu fault */
	cpu_restore_state(cs, retaddr);
	arm_deliver_fault(cpu, address, access_type, mmu_idx, fi);
	}
	}
	#else
	void arm_cpu_record_sigsegv(CPUState *cs, vaddr addr,
	MMUAccessType access_type,
	bool maperr, uintptr_t ra)
	{
	ARMMMUFaultInfo fi = {
	.type = maperr ? ARMFault_Translation : ARMFault_Permission,
	.level = 3,
	};
	ARMCPU *cpu = ARM_CPU(cs);

	/*
	* We report both ESR and FAR to signal handlers.
	* For now, it's easiest to deliver the fault normally.
	*/
	cpu_restore_state(cs, ra);
	arm_deliver_fault(cpu, addr, access_type, MMU_USER_IDX, &fi);
	}

	void arm_cpu_record_sigbus(CPUState *cs, vaddr addr,
	MMUAccessType access_type, uintptr_t ra)
	{
	arm_cpu_do_unaligned_access(cs, addr, access_type, MMU_USER_IDX, ra);
	}
	#endif /* !defined(CONFIG_USER_ONLY) */