/* * ARM generic 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 "qemu/units.h" #include "target/arm/idau.h" #include "trace.h" #include "cpu.h" #include "internals.h" #include "exec/gdbstub.h" #include "exec/helper-proto.h" #include "qemu/host-utils.h" #include "qemu/main-loop.h" #include "qemu/bitops.h" #include "qemu/crc32c.h" #include "qemu/qemu-print.h" #include "exec/exec-all.h" #include /* For crc32 */ #include "hw/semihosting/semihost.h" #include "sysemu/cpus.h" #include "sysemu/kvm.h" #include "qemu/range.h" #include "qapi/qapi-commands-machine-target.h" #include "qapi/error.h" #include "qemu/guest-random.h" #ifdef CONFIG_TCG #include "arm_ldst.h" #include "exec/cpu_ldst.h" #endif static void v7m_msr_xpsr(CPUARMState *env, uint32_t mask, uint32_t reg, uint32_t val) { /* Only APSR is actually writable */ if (!(reg & 4)) { uint32_t apsrmask = 0; if (mask & 8) { apsrmask |= XPSR_NZCV | XPSR_Q; } if ((mask & 4) && arm_feature(env, ARM_FEATURE_THUMB_DSP)) { apsrmask |= XPSR_GE; } xpsr_write(env, val, apsrmask); } } static uint32_t v7m_mrs_xpsr(CPUARMState *env, uint32_t reg, unsigned el) { uint32_t mask = 0; if ((reg & 1) && el) { mask |= XPSR_EXCP; /* IPSR (unpriv. reads as zero) */ } if (!(reg & 4)) { mask |= XPSR_NZCV | XPSR_Q; /* APSR */ if (arm_feature(env, ARM_FEATURE_THUMB_DSP)) { mask |= XPSR_GE; } } /* EPSR reads as zero */ return xpsr_read(env) & mask; } static uint32_t v7m_mrs_control(CPUARMState *env, uint32_t secure) { uint32_t value = env->v7m.control[secure]; if (!secure) { /* SFPA is RAZ/WI from NS; FPCA is stored in the M_REG_S bank */ value |= env->v7m.control[M_REG_S] & R_V7M_CONTROL_FPCA_MASK; } return value; } #ifdef CONFIG_USER_ONLY void HELPER(v7m_msr)(CPUARMState *env, uint32_t maskreg, uint32_t val) { uint32_t mask = extract32(maskreg, 8, 4); uint32_t reg = extract32(maskreg, 0, 8); switch (reg) { case 0 ... 7: /* xPSR sub-fields */ v7m_msr_xpsr(env, mask, reg, val); break; case 20: /* CONTROL */ /* There are no sub-fields that are actually writable from EL0. */ break; default: /* Unprivileged writes to other registers are ignored */ break; } } uint32_t HELPER(v7m_mrs)(CPUARMState *env, uint32_t reg) { switch (reg) { case 0 ... 7: /* xPSR sub-fields */ return v7m_mrs_xpsr(env, reg, 0); case 20: /* CONTROL */ return v7m_mrs_control(env, 0); default: /* Unprivileged reads others as zero. */ return 0; } } void HELPER(v7m_bxns)(CPUARMState *env, uint32_t dest) { /* translate.c should never generate calls here in user-only mode */ g_assert_not_reached(); } void HELPER(v7m_blxns)(CPUARMState *env, uint32_t dest) { /* translate.c should never generate calls here in user-only mode */ g_assert_not_reached(); } void HELPER(v7m_preserve_fp_state)(CPUARMState *env) { /* translate.c should never generate calls here in user-only mode */ g_assert_not_reached(); } void HELPER(v7m_vlstm)(CPUARMState *env, uint32_t fptr) { /* translate.c should never generate calls here in user-only mode */ g_assert_not_reached(); } void HELPER(v7m_vlldm)(CPUARMState *env, uint32_t fptr) { /* translate.c should never generate calls here in user-only mode */ g_assert_not_reached(); } uint32_t HELPER(v7m_tt)(CPUARMState *env, uint32_t addr, uint32_t op) { /* * The TT instructions can be used by unprivileged code, but in * user-only emulation we don't have the MPU. * Luckily since we know we are NonSecure unprivileged (and that in * turn means that the A flag wasn't specified), all the bits in the * register must be zero: * IREGION: 0 because IRVALID is 0 * IRVALID: 0 because NS * S: 0 because NS * NSRW: 0 because NS * NSR: 0 because NS * RW: 0 because unpriv and A flag not set * R: 0 because unpriv and A flag not set * SRVALID: 0 because NS * MRVALID: 0 because unpriv and A flag not set * SREGION: 0 becaus SRVALID is 0 * MREGION: 0 because MRVALID is 0 */ return 0; } #else /* * What kind of stack write are we doing? This affects how exceptions * generated during the stacking are treated. */ typedef enum StackingMode { STACK_NORMAL, STACK_IGNFAULTS, STACK_LAZYFP, } StackingMode; static bool v7m_stack_write(ARMCPU *cpu, uint32_t addr, uint32_t value, ARMMMUIdx mmu_idx, StackingMode mode) { CPUState *cs = CPU(cpu); CPUARMState *env = &cpu->env; MemTxAttrs attrs = {}; MemTxResult txres; target_ulong page_size; hwaddr physaddr; int prot; ARMMMUFaultInfo fi = {}; bool secure = mmu_idx & ARM_MMU_IDX_M_S; int exc; bool exc_secure; if (get_phys_addr(env, addr, MMU_DATA_STORE, mmu_idx, &physaddr, &attrs, &prot, &page_size, &fi, NULL)) { /* MPU/SAU lookup failed */ if (fi.type == ARMFault_QEMU_SFault) { if (mode == STACK_LAZYFP) { qemu_log_mask(CPU_LOG_INT, "...SecureFault with SFSR.LSPERR " "during lazy stacking\n"); env->v7m.sfsr |= R_V7M_SFSR_LSPERR_MASK; } else { qemu_log_mask(CPU_LOG_INT, "...SecureFault with SFSR.AUVIOL " "during stacking\n"); env->v7m.sfsr |= R_V7M_SFSR_AUVIOL_MASK; } env->v7m.sfsr |= R_V7M_SFSR_SFARVALID_MASK; env->v7m.sfar = addr; exc = ARMV7M_EXCP_SECURE; exc_secure = false; } else { if (mode == STACK_LAZYFP) { qemu_log_mask(CPU_LOG_INT, "...MemManageFault with CFSR.MLSPERR\n"); env->v7m.cfsr[secure] |= R_V7M_CFSR_MLSPERR_MASK; } else { qemu_log_mask(CPU_LOG_INT, "...MemManageFault with CFSR.MSTKERR\n"); env->v7m.cfsr[secure] |= R_V7M_CFSR_MSTKERR_MASK; } exc = ARMV7M_EXCP_MEM; exc_secure = secure; } goto pend_fault; } address_space_stl_le(arm_addressspace(cs, attrs), physaddr, value, attrs, &txres); if (txres != MEMTX_OK) { /* BusFault trying to write the data */ if (mode == STACK_LAZYFP) { qemu_log_mask(CPU_LOG_INT, "...BusFault with BFSR.LSPERR\n"); env->v7m.cfsr[M_REG_NS] |= R_V7M_CFSR_LSPERR_MASK; } else { qemu_log_mask(CPU_LOG_INT, "...BusFault with BFSR.STKERR\n"); env->v7m.cfsr[M_REG_NS] |= R_V7M_CFSR_STKERR_MASK; } exc = ARMV7M_EXCP_BUS; exc_secure = false; goto pend_fault; } return true; pend_fault: /* * By pending the exception at this point we are making * the IMPDEF choice "overridden exceptions pended" (see the * MergeExcInfo() pseudocode). The other choice would be to not * pend them now and then make a choice about which to throw away * later if we have two derived exceptions. * The only case when we must not pend the exception but instead * throw it away is if we are doing the push of the callee registers * and we've already generated a derived exception (this is indicated * by the caller passing STACK_IGNFAULTS). Even in this case we will * still update the fault status registers. */ switch (mode) { case STACK_NORMAL: armv7m_nvic_set_pending_derived(env->nvic, exc, exc_secure); break; case STACK_LAZYFP: armv7m_nvic_set_pending_lazyfp(env->nvic, exc, exc_secure); break; case STACK_IGNFAULTS: break; } return false; } static bool v7m_stack_read(ARMCPU *cpu, uint32_t *dest, uint32_t addr, ARMMMUIdx mmu_idx) { CPUState *cs = CPU(cpu); CPUARMState *env = &cpu->env; MemTxAttrs attrs = {}; MemTxResult txres; target_ulong page_size; hwaddr physaddr; int prot; ARMMMUFaultInfo fi = {}; bool secure = mmu_idx & ARM_MMU_IDX_M_S; int exc; bool exc_secure; uint32_t value; if (get_phys_addr(env, addr, MMU_DATA_LOAD, mmu_idx, &physaddr, &attrs, &prot, &page_size, &fi, NULL)) { /* MPU/SAU lookup failed */ if (fi.type == ARMFault_QEMU_SFault) { qemu_log_mask(CPU_LOG_INT, "...SecureFault with SFSR.AUVIOL during unstack\n"); env->v7m.sfsr |= R_V7M_SFSR_AUVIOL_MASK | R_V7M_SFSR_SFARVALID_MASK; env->v7m.sfar = addr; exc = ARMV7M_EXCP_SECURE; exc_secure = false; } else { qemu_log_mask(CPU_LOG_INT, "...MemManageFault with CFSR.MUNSTKERR\n"); env->v7m.cfsr[secure] |= R_V7M_CFSR_MUNSTKERR_MASK; exc = ARMV7M_EXCP_MEM; exc_secure = secure; } goto pend_fault; } value = address_space_ldl(arm_addressspace(cs, attrs), physaddr, attrs, &txres); if (txres != MEMTX_OK) { /* BusFault trying to read the data */ qemu_log_mask(CPU_LOG_INT, "...BusFault with BFSR.UNSTKERR\n"); env->v7m.cfsr[M_REG_NS] |= R_V7M_CFSR_UNSTKERR_MASK; exc = ARMV7M_EXCP_BUS; exc_secure = false; goto pend_fault; } *dest = value; return true; pend_fault: /* * By pending the exception at this point we are making * the IMPDEF choice "overridden exceptions pended" (see the * MergeExcInfo() pseudocode). The other choice would be to not * pend them now and then make a choice about which to throw away * later if we have two derived exceptions. */ armv7m_nvic_set_pending(env->nvic, exc, exc_secure); return false; } void HELPER(v7m_preserve_fp_state)(CPUARMState *env) { /* * Preserve FP state (because LSPACT was set and we are about * to execute an FP instruction). This corresponds to the * PreserveFPState() pseudocode. * We may throw an exception if the stacking fails. */ ARMCPU *cpu = env_archcpu(env); bool is_secure = env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_S_MASK; bool negpri = !(env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_HFRDY_MASK); bool is_priv = !(env->v7m.fpccr[is_secure] & R_V7M_FPCCR_USER_MASK); bool splimviol = env->v7m.fpccr[is_secure] & R_V7M_FPCCR_SPLIMVIOL_MASK; uint32_t fpcar = env->v7m.fpcar[is_secure]; bool stacked_ok = true; bool ts = is_secure && (env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_TS_MASK); bool take_exception; /* Take the iothread lock as we are going to touch the NVIC */ qemu_mutex_lock_iothread(); /* Check the background context had access to the FPU */ if (!v7m_cpacr_pass(env, is_secure, is_priv)) { armv7m_nvic_set_pending_lazyfp(env->nvic, ARMV7M_EXCP_USAGE, is_secure); env->v7m.cfsr[is_secure] |= R_V7M_CFSR_NOCP_MASK; stacked_ok = false; } else if (!is_secure && !extract32(env->v7m.nsacr, 10, 1)) { armv7m_nvic_set_pending_lazyfp(env->nvic, ARMV7M_EXCP_USAGE, M_REG_S); env->v7m.cfsr[M_REG_S] |= R_V7M_CFSR_NOCP_MASK; stacked_ok = false; } if (!splimviol && stacked_ok) { /* We only stack if the stack limit wasn't violated */ int i; ARMMMUIdx mmu_idx; mmu_idx = arm_v7m_mmu_idx_all(env, is_secure, is_priv, negpri); for (i = 0; i < (ts ? 32 : 16); i += 2) { uint64_t dn = *aa32_vfp_dreg(env, i / 2); uint32_t faddr = fpcar + 4 * i; uint32_t slo = extract64(dn, 0, 32); uint32_t shi = extract64(dn, 32, 32); if (i >= 16) { faddr += 8; /* skip the slot for the FPSCR */ } stacked_ok = stacked_ok && v7m_stack_write(cpu, faddr, slo, mmu_idx, STACK_LAZYFP) && v7m_stack_write(cpu, faddr + 4, shi, mmu_idx, STACK_LAZYFP); } stacked_ok = stacked_ok && v7m_stack_write(cpu, fpcar + 0x40, vfp_get_fpscr(env), mmu_idx, STACK_LAZYFP); } /* * We definitely pended an exception, but it's possible that it * might not be able to be taken now. If its priority permits us * to take it now, then we must not update the LSPACT or FP regs, * but instead jump out to take the exception immediately. * If it's just pending and won't be taken until the current * handler exits, then we do update LSPACT and the FP regs. */ take_exception = !stacked_ok && armv7m_nvic_can_take_pending_exception(env->nvic); qemu_mutex_unlock_iothread(); if (take_exception) { raise_exception_ra(env, EXCP_LAZYFP, 0, 1, GETPC()); } env->v7m.fpccr[is_secure] &= ~R_V7M_FPCCR_LSPACT_MASK; if (ts) { /* Clear s0 to s31 and the FPSCR */ int i; for (i = 0; i < 32; i += 2) { *aa32_vfp_dreg(env, i / 2) = 0; } vfp_set_fpscr(env, 0); } /* * Otherwise s0 to s15 and FPSCR are UNKNOWN; we choose to leave them * unchanged. */ } /* * Write to v7M CONTROL.SPSEL bit for the specified security bank. * This may change the current stack pointer between Main and Process * stack pointers if it is done for the CONTROL register for the current * security state. */ static void write_v7m_control_spsel_for_secstate(CPUARMState *env, bool new_spsel, bool secstate) { bool old_is_psp = v7m_using_psp(env); env->v7m.control[secstate] = deposit32(env->v7m.control[secstate], R_V7M_CONTROL_SPSEL_SHIFT, R_V7M_CONTROL_SPSEL_LENGTH, new_spsel); if (secstate == env->v7m.secure) { bool new_is_psp = v7m_using_psp(env); uint32_t tmp; if (old_is_psp != new_is_psp) { tmp = env->v7m.other_sp; env->v7m.other_sp = env->regs[13]; env->regs[13] = tmp; } } } /* * Write to v7M CONTROL.SPSEL bit. This may change the current * stack pointer between Main and Process stack pointers. */ static void write_v7m_control_spsel(CPUARMState *env, bool new_spsel) { write_v7m_control_spsel_for_secstate(env, new_spsel, env->v7m.secure); } void write_v7m_exception(CPUARMState *env, uint32_t new_exc) { /* * Write a new value to v7m.exception, thus transitioning into or out * of Handler mode; this may result in a change of active stack pointer. */ bool new_is_psp, old_is_psp = v7m_using_psp(env); uint32_t tmp; env->v7m.exception = new_exc; new_is_psp = v7m_using_psp(env); if (old_is_psp != new_is_psp) { tmp = env->v7m.other_sp; env->v7m.other_sp = env->regs[13]; env->regs[13] = tmp; } } /* Switch M profile security state between NS and S */ static void switch_v7m_security_state(CPUARMState *env, bool new_secstate) { uint32_t new_ss_msp, new_ss_psp; if (env->v7m.secure == new_secstate) { return; } /* * All the banked state is accessed by looking at env->v7m.secure * except for the stack pointer; rearrange the SP appropriately. */ new_ss_msp = env->v7m.other_ss_msp; new_ss_psp = env->v7m.other_ss_psp; if (v7m_using_psp(env)) { env->v7m.other_ss_psp = env->regs[13]; env->v7m.other_ss_msp = env->v7m.other_sp; } else { env->v7m.other_ss_msp = env->regs[13]; env->v7m.other_ss_psp = env->v7m.other_sp; } env->v7m.secure = new_secstate; if (v7m_using_psp(env)) { env->regs[13] = new_ss_psp; env->v7m.other_sp = new_ss_msp; } else { env->regs[13] = new_ss_msp; env->v7m.other_sp = new_ss_psp; } } void HELPER(v7m_bxns)(CPUARMState *env, uint32_t dest) { /* * Handle v7M BXNS: * - if the return value is a magic value, do exception return (like BX) * - otherwise bit 0 of the return value is the target security state */ uint32_t min_magic; if (arm_feature(env, ARM_FEATURE_M_SECURITY)) { /* Covers FNC_RETURN and EXC_RETURN magic */ min_magic = FNC_RETURN_MIN_MAGIC; } else { /* EXC_RETURN magic only */ min_magic = EXC_RETURN_MIN_MAGIC; } if (dest >= min_magic) { /* * This is an exception return magic value; put it where * do_v7m_exception_exit() expects and raise EXCEPTION_EXIT. * Note that if we ever add gen_ss_advance() singlestep support to * M profile this should count as an "instruction execution complete" * event (compare gen_bx_excret_final_code()). */ env->regs[15] = dest & ~1; env->thumb = dest & 1; HELPER(exception_internal)(env, EXCP_EXCEPTION_EXIT); /* notreached */ } /* translate.c should have made BXNS UNDEF unless we're secure */ assert(env->v7m.secure); if (!(dest & 1)) { env->v7m.control[M_REG_S] &= ~R_V7M_CONTROL_SFPA_MASK; } switch_v7m_security_state(env, dest & 1); env->thumb = 1; env->regs[15] = dest & ~1; arm_rebuild_hflags(env); } void HELPER(v7m_blxns)(CPUARMState *env, uint32_t dest) { /* * Handle v7M BLXNS: * - bit 0 of the destination address is the target security state */ /* At this point regs[15] is the address just after the BLXNS */ uint32_t nextinst = env->regs[15] | 1; uint32_t sp = env->regs[13] - 8; uint32_t saved_psr; /* translate.c will have made BLXNS UNDEF unless we're secure */ assert(env->v7m.secure); if (dest & 1) { /* * Target is Secure, so this is just a normal BLX, * except that the low bit doesn't indicate Thumb/not. */ env->regs[14] = nextinst; env->thumb = 1; env->regs[15] = dest & ~1; return; } /* Target is non-secure: first push a stack frame */ if (!QEMU_IS_ALIGNED(sp, 8)) { qemu_log_mask(LOG_GUEST_ERROR, "BLXNS with misaligned SP is UNPREDICTABLE\n"); } if (sp < v7m_sp_limit(env)) { raise_exception(env, EXCP_STKOF, 0, 1); } saved_psr = env->v7m.exception; if (env->v7m.control[M_REG_S] & R_V7M_CONTROL_SFPA_MASK) { saved_psr |= XPSR_SFPA; } /* Note that these stores can throw exceptions on MPU faults */ cpu_stl_data_ra(env, sp, nextinst, GETPC()); cpu_stl_data_ra(env, sp + 4, saved_psr, GETPC()); env->regs[13] = sp; env->regs[14] = 0xfeffffff; if (arm_v7m_is_handler_mode(env)) { /* * Write a dummy value to IPSR, to avoid leaking the current secure * exception number to non-secure code. This is guaranteed not * to cause write_v7m_exception() to actually change stacks. */ write_v7m_exception(env, 1); } env->v7m.control[M_REG_S] &= ~R_V7M_CONTROL_SFPA_MASK; switch_v7m_security_state(env, 0); env->thumb = 1; env->regs[15] = dest; arm_rebuild_hflags(env); } static uint32_t *get_v7m_sp_ptr(CPUARMState *env, bool secure, bool threadmode, bool spsel) { /* * Return a pointer to the location where we currently store the * stack pointer for the requested security state and thread mode. * This pointer will become invalid if the CPU state is updated * such that the stack pointers are switched around (eg changing * the SPSEL control bit). * Compare the v8M ARM ARM pseudocode LookUpSP_with_security_mode(). * Unlike that pseudocode, we require the caller to pass us in the * SPSEL control bit value; this is because we also use this * function in handling of pushing of the callee-saves registers * part of the v8M stack frame (pseudocode PushCalleeStack()), * and in the tailchain codepath the SPSEL bit comes from the exception * return magic LR value from the previous exception. The pseudocode * opencodes the stack-selection in PushCalleeStack(), but we prefer * to make this utility function generic enough to do the job. */ bool want_psp = threadmode && spsel; if (secure == env->v7m.secure) { if (want_psp == v7m_using_psp(env)) { return &env->regs[13]; } else { return &env->v7m.other_sp; } } else { if (want_psp) { return &env->v7m.other_ss_psp; } else { return &env->v7m.other_ss_msp; } } } static bool arm_v7m_load_vector(ARMCPU *cpu, int exc, bool targets_secure, uint32_t *pvec) { CPUState *cs = CPU(cpu); CPUARMState *env = &cpu->env; MemTxResult result; uint32_t addr = env->v7m.vecbase[targets_secure] + exc * 4; uint32_t vector_entry; MemTxAttrs attrs = {}; ARMMMUIdx mmu_idx; bool exc_secure; mmu_idx = arm_v7m_mmu_idx_for_secstate_and_priv(env, targets_secure, true); /* * We don't do a get_phys_addr() here because the rules for vector * loads are special: they always use the default memory map, and * the default memory map permits reads from all addresses. * Since there's no easy way to pass through to pmsav8_mpu_lookup() * that we want this special case which would always say "yes", * we just do the SAU lookup here followed by a direct physical load. */ attrs.secure = targets_secure; attrs.user = false; if (arm_feature(env, ARM_FEATURE_M_SECURITY)) { V8M_SAttributes sattrs = {}; v8m_security_lookup(env, addr, MMU_DATA_LOAD, mmu_idx, &sattrs); if (sattrs.ns) { attrs.secure = false; } else if (!targets_secure) { /* * NS access to S memory: the underlying exception which we escalate * to HardFault is SecureFault, which always targets Secure. */ exc_secure = true; goto load_fail; } } vector_entry = address_space_ldl(arm_addressspace(cs, attrs), addr, attrs, &result); if (result != MEMTX_OK) { /* * Underlying exception is BusFault: its target security state * depends on BFHFNMINS. */ exc_secure = !(cpu->env.v7m.aircr & R_V7M_AIRCR_BFHFNMINS_MASK); goto load_fail; } *pvec = vector_entry; return true; load_fail: /* * All vector table fetch fails are reported as HardFault, with * HFSR.VECTTBL and .FORCED set. (FORCED is set because * technically the underlying exception is a SecureFault or BusFault * that is escalated to HardFault.) This is a terminal exception, * so we will either take the HardFault immediately or else enter * lockup (the latter case is handled in armv7m_nvic_set_pending_derived()). * The HardFault is Secure if BFHFNMINS is 0 (meaning that all HFs are * secure); otherwise it targets the same security state as the * underlying exception. */ if (!(cpu->env.v7m.aircr & R_V7M_AIRCR_BFHFNMINS_MASK)) { exc_secure = true; } env->v7m.hfsr |= R_V7M_HFSR_VECTTBL_MASK | R_V7M_HFSR_FORCED_MASK; armv7m_nvic_set_pending_derived(env->nvic, ARMV7M_EXCP_HARD, exc_secure); return false; } static uint32_t v7m_integrity_sig(CPUARMState *env, uint32_t lr) { /* * Return the integrity signature value for the callee-saves * stack frame section. @lr is the exception return payload/LR value * whose FType bit forms bit 0 of the signature if FP is present. */ uint32_t sig = 0xfefa125a; if (!arm_feature(env, ARM_FEATURE_VFP) || (lr & R_V7M_EXCRET_FTYPE_MASK)) { sig |= 1; } return sig; } static bool v7m_push_callee_stack(ARMCPU *cpu, uint32_t lr, bool dotailchain, bool ignore_faults) { /* * For v8M, push the callee-saves register part of the stack frame. * Compare the v8M pseudocode PushCalleeStack(). * In the tailchaining case this may not be the current stack. */ CPUARMState *env = &cpu->env; uint32_t *frame_sp_p; uint32_t frameptr; ARMMMUIdx mmu_idx; bool stacked_ok; uint32_t limit; bool want_psp; uint32_t sig; StackingMode smode = ignore_faults ? STACK_IGNFAULTS : STACK_NORMAL; if (dotailchain) { bool mode = lr & R_V7M_EXCRET_MODE_MASK; bool priv = !(env->v7m.control[M_REG_S] & R_V7M_CONTROL_NPRIV_MASK) || !mode; mmu_idx = arm_v7m_mmu_idx_for_secstate_and_priv(env, M_REG_S, priv); frame_sp_p = get_v7m_sp_ptr(env, M_REG_S, mode, lr & R_V7M_EXCRET_SPSEL_MASK); want_psp = mode && (lr & R_V7M_EXCRET_SPSEL_MASK); if (want_psp) { limit = env->v7m.psplim[M_REG_S]; } else { limit = env->v7m.msplim[M_REG_S]; } } else { mmu_idx = arm_mmu_idx(env); frame_sp_p = &env->regs[13]; limit = v7m_sp_limit(env); } frameptr = *frame_sp_p - 0x28; if (frameptr < limit) { /* * Stack limit failure: set SP to the limit value, and generate * STKOF UsageFault. Stack pushes below the limit must not be * performed. It is IMPDEF whether pushes above the limit are * performed; we choose not to. */ qemu_log_mask(CPU_LOG_INT, "...STKOF during callee-saves register stacking\n"); env->v7m.cfsr[env->v7m.secure] |= R_V7M_CFSR_STKOF_MASK; armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE, env->v7m.secure); *frame_sp_p = limit; return true; } /* * Write as much of the stack frame as we can. A write failure may * cause us to pend a derived exception. */ sig = v7m_integrity_sig(env, lr); stacked_ok = v7m_stack_write(cpu, frameptr, sig, mmu_idx, smode) && v7m_stack_write(cpu, frameptr + 0x8, env->regs[4], mmu_idx, smode) && v7m_stack_write(cpu, frameptr + 0xc, env->regs[5], mmu_idx, smode) && v7m_stack_write(cpu, frameptr + 0x10, env->regs[6], mmu_idx, smode) && v7m_stack_write(cpu, frameptr + 0x14, env->regs[7], mmu_idx, smode) && v7m_stack_write(cpu, frameptr + 0x18, env->regs[8], mmu_idx, smode) && v7m_stack_write(cpu, frameptr + 0x1c, env->regs[9], mmu_idx, smode) && v7m_stack_write(cpu, frameptr + 0x20, env->regs[10], mmu_idx, smode) && v7m_stack_write(cpu, frameptr + 0x24, env->regs[11], mmu_idx, smode); /* Update SP regardless of whether any of the stack accesses failed. */ *frame_sp_p = frameptr; return !stacked_ok; } static void v7m_exception_taken(ARMCPU *cpu, uint32_t lr, bool dotailchain, bool ignore_stackfaults) { /* * Do the "take the exception" parts of exception entry, * but not the pushing of state to the stack. This is * similar to the pseudocode ExceptionTaken() function. */ CPUARMState *env = &cpu->env; uint32_t addr; bool targets_secure; int exc; bool push_failed = false; armv7m_nvic_get_pending_irq_info(env->nvic, &exc, &targets_secure); qemu_log_mask(CPU_LOG_INT, "...taking pending %s exception %d\n", targets_secure ? "secure" : "nonsecure", exc); if (dotailchain) { /* Sanitize LR FType and PREFIX bits */ if (!arm_feature(env, ARM_FEATURE_VFP)) { lr |= R_V7M_EXCRET_FTYPE_MASK; } lr = deposit32(lr, 24, 8, 0xff); } if (arm_feature(env, ARM_FEATURE_V8)) { if (arm_feature(env, ARM_FEATURE_M_SECURITY) && (lr & R_V7M_EXCRET_S_MASK)) { /* * The background code (the owner of the registers in the * exception frame) is Secure. This means it may either already * have or now needs to push callee-saves registers. */ if (targets_secure) { if (dotailchain && !(lr & R_V7M_EXCRET_ES_MASK)) { /* * We took an exception from Secure to NonSecure * (which means the callee-saved registers got stacked) * and are now tailchaining to a Secure exception. * Clear DCRS so eventual return from this Secure * exception unstacks the callee-saved registers. */ lr &= ~R_V7M_EXCRET_DCRS_MASK; } } else { /* * We're going to a non-secure exception; push the * callee-saves registers to the stack now, if they're * not already saved. */ if (lr & R_V7M_EXCRET_DCRS_MASK && !(dotailchain && !(lr & R_V7M_EXCRET_ES_MASK))) { push_failed = v7m_push_callee_stack(cpu, lr, dotailchain, ignore_stackfaults); } lr |= R_V7M_EXCRET_DCRS_MASK; } } lr &= ~R_V7M_EXCRET_ES_MASK; if (targets_secure || !arm_feature(env, ARM_FEATURE_M_SECURITY)) { lr |= R_V7M_EXCRET_ES_MASK; } lr &= ~R_V7M_EXCRET_SPSEL_MASK; if (env->v7m.control[targets_secure] & R_V7M_CONTROL_SPSEL_MASK) { lr |= R_V7M_EXCRET_SPSEL_MASK; } /* * Clear registers if necessary to prevent non-secure exception * code being able to see register values from secure code. * Where register values become architecturally UNKNOWN we leave * them with their previous values. */ if (arm_feature(env, ARM_FEATURE_M_SECURITY)) { if (!targets_secure) { /* * Always clear the caller-saved registers (they have been * pushed to the stack earlier in v7m_push_stack()). * Clear callee-saved registers if the background code is * Secure (in which case these regs were saved in * v7m_push_callee_stack()). */ int i; for (i = 0; i < 13; i++) { /* r4..r11 are callee-saves, zero only if EXCRET.S == 1 */ if (i < 4 || i > 11 || (lr & R_V7M_EXCRET_S_MASK)) { env->regs[i] = 0; } } /* Clear EAPSR */ xpsr_write(env, 0, XPSR_NZCV | XPSR_Q | XPSR_GE | XPSR_IT); } } } if (push_failed && !ignore_stackfaults) { /* * Derived exception on callee-saves register stacking: * we might now want to take a different exception which * targets a different security state, so try again from the top. */ qemu_log_mask(CPU_LOG_INT, "...derived exception on callee-saves register stacking"); v7m_exception_taken(cpu, lr, true, true); return; } if (!arm_v7m_load_vector(cpu, exc, targets_secure, &addr)) { /* Vector load failed: derived exception */ qemu_log_mask(CPU_LOG_INT, "...derived exception on vector table load"); v7m_exception_taken(cpu, lr, true, true); return; } /* * Now we've done everything that might cause a derived exception * we can go ahead and activate whichever exception we're going to * take (which might now be the derived exception). */ armv7m_nvic_acknowledge_irq(env->nvic); /* Switch to target security state -- must do this before writing SPSEL */ switch_v7m_security_state(env, targets_secure); write_v7m_control_spsel(env, 0); arm_clear_exclusive(env); /* Clear SFPA and FPCA (has no effect if no FPU) */ env->v7m.control[M_REG_S] &= ~(R_V7M_CONTROL_FPCA_MASK | R_V7M_CONTROL_SFPA_MASK); /* Clear IT bits */ env->condexec_bits = 0; env->regs[14] = lr; env->regs[15] = addr & 0xfffffffe; env->thumb = addr & 1; arm_rebuild_hflags(env); } static void v7m_update_fpccr(CPUARMState *env, uint32_t frameptr, bool apply_splim) { /* * Like the pseudocode UpdateFPCCR: save state in FPCAR and FPCCR * that we will need later in order to do lazy FP reg stacking. */ bool is_secure = env->v7m.secure; void *nvic = env->nvic; /* * Some bits are unbanked and live always in fpccr[M_REG_S]; some bits * are banked and we want to update the bit in the bank for the * current security state; and in one case we want to specifically * update the NS banked version of a bit even if we are secure. */ uint32_t *fpccr_s = &env->v7m.fpccr[M_REG_S]; uint32_t *fpccr_ns = &env->v7m.fpccr[M_REG_NS]; uint32_t *fpccr = &env->v7m.fpccr[is_secure]; bool hfrdy, bfrdy, mmrdy, ns_ufrdy, s_ufrdy, sfrdy, monrdy; env->v7m.fpcar[is_secure] = frameptr & ~0x7; if (apply_splim && arm_feature(env, ARM_FEATURE_V8)) { bool splimviol; uint32_t splim = v7m_sp_limit(env); bool ign = armv7m_nvic_neg_prio_requested(nvic, is_secure) && (env->v7m.ccr[is_secure] & R_V7M_CCR_STKOFHFNMIGN_MASK); splimviol = !ign && frameptr < splim; *fpccr = FIELD_DP32(*fpccr, V7M_FPCCR, SPLIMVIOL, splimviol); } *fpccr = FIELD_DP32(*fpccr, V7M_FPCCR, LSPACT, 1); *fpccr_s = FIELD_DP32(*fpccr_s, V7M_FPCCR, S, is_secure); *fpccr = FIELD_DP32(*fpccr, V7M_FPCCR, USER, arm_current_el(env) == 0); *fpccr = FIELD_DP32(*fpccr, V7M_FPCCR, THREAD, !arm_v7m_is_handler_mode(env)); hfrdy = armv7m_nvic_get_ready_status(nvic, ARMV7M_EXCP_HARD, false); *fpccr_s = FIELD_DP32(*fpccr_s, V7M_FPCCR, HFRDY, hfrdy); bfrdy = armv7m_nvic_get_ready_status(nvic, ARMV7M_EXCP_BUS, false); *fpccr_s = FIELD_DP32(*fpccr_s, V7M_FPCCR, BFRDY, bfrdy); mmrdy = armv7m_nvic_get_ready_status(nvic, ARMV7M_EXCP_MEM, is_secure); *fpccr = FIELD_DP32(*fpccr, V7M_FPCCR, MMRDY, mmrdy); ns_ufrdy = armv7m_nvic_get_ready_status(nvic, ARMV7M_EXCP_USAGE, false); *fpccr_ns = FIELD_DP32(*fpccr_ns, V7M_FPCCR, UFRDY, ns_ufrdy); monrdy = armv7m_nvic_get_ready_status(nvic, ARMV7M_EXCP_DEBUG, false); *fpccr_s = FIELD_DP32(*fpccr_s, V7M_FPCCR, MONRDY, monrdy); if (arm_feature(env, ARM_FEATURE_M_SECURITY)) { s_ufrdy = armv7m_nvic_get_ready_status(nvic, ARMV7M_EXCP_USAGE, true); *fpccr_s = FIELD_DP32(*fpccr_s, V7M_FPCCR, UFRDY, s_ufrdy); sfrdy = armv7m_nvic_get_ready_status(nvic, ARMV7M_EXCP_SECURE, false); *fpccr_s = FIELD_DP32(*fpccr_s, V7M_FPCCR, SFRDY, sfrdy); } } void HELPER(v7m_vlstm)(CPUARMState *env, uint32_t fptr) { /* fptr is the value of Rn, the frame pointer we store the FP regs to */ bool s = env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_S_MASK; bool lspact = env->v7m.fpccr[s] & R_V7M_FPCCR_LSPACT_MASK; uintptr_t ra = GETPC(); assert(env->v7m.secure); if (!(env->v7m.control[M_REG_S] & R_V7M_CONTROL_SFPA_MASK)) { return; } /* Check access to the coprocessor is permitted */ if (!v7m_cpacr_pass(env, true, arm_current_el(env) != 0)) { raise_exception_ra(env, EXCP_NOCP, 0, 1, GETPC()); } if (lspact) { /* LSPACT should not be active when there is active FP state */ raise_exception_ra(env, EXCP_LSERR, 0, 1, GETPC()); } if (fptr & 7) { raise_exception_ra(env, EXCP_UNALIGNED, 0, 1, GETPC()); } /* * Note that we do not use v7m_stack_write() here, because the * accesses should not set the FSR bits for stacking errors if they * fail. (In pseudocode terms, they are AccType_NORMAL, not AccType_STACK * or AccType_LAZYFP). Faults in cpu_stl_data_ra() will throw exceptions * and longjmp out. */ if (!(env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_LSPEN_MASK)) { bool ts = env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_TS_MASK; int i; for (i = 0; i < (ts ? 32 : 16); i += 2) { uint64_t dn = *aa32_vfp_dreg(env, i / 2); uint32_t faddr = fptr + 4 * i; uint32_t slo = extract64(dn, 0, 32); uint32_t shi = extract64(dn, 32, 32); if (i >= 16) { faddr += 8; /* skip the slot for the FPSCR */ } cpu_stl_data_ra(env, faddr, slo, ra); cpu_stl_data_ra(env, faddr + 4, shi, ra); } cpu_stl_data_ra(env, fptr + 0x40, vfp_get_fpscr(env), ra); /* * If TS is 0 then s0 to s15 and FPSCR are UNKNOWN; we choose to * leave them unchanged, matching our choice in v7m_preserve_fp_state. */ if (ts) { for (i = 0; i < 32; i += 2) { *aa32_vfp_dreg(env, i / 2) = 0; } vfp_set_fpscr(env, 0); } } else { v7m_update_fpccr(env, fptr, false); } env->v7m.control[M_REG_S] &= ~R_V7M_CONTROL_FPCA_MASK; } void HELPER(v7m_vlldm)(CPUARMState *env, uint32_t fptr) { uintptr_t ra = GETPC(); /* fptr is the value of Rn, the frame pointer we load the FP regs from */ assert(env->v7m.secure); if (!(env->v7m.control[M_REG_S] & R_V7M_CONTROL_SFPA_MASK)) { return; } /* Check access to the coprocessor is permitted */ if (!v7m_cpacr_pass(env, true, arm_current_el(env) != 0)) { raise_exception_ra(env, EXCP_NOCP, 0, 1, GETPC()); } if (env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_LSPACT_MASK) { /* State in FP is still valid */ env->v7m.fpccr[M_REG_S] &= ~R_V7M_FPCCR_LSPACT_MASK; } else { bool ts = env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_TS_MASK; int i; uint32_t fpscr; if (fptr & 7) { raise_exception_ra(env, EXCP_UNALIGNED, 0, 1, GETPC()); } for (i = 0; i < (ts ? 32 : 16); i += 2) { uint32_t slo, shi; uint64_t dn; uint32_t faddr = fptr + 4 * i; if (i >= 16) { faddr += 8; /* skip the slot for the FPSCR */ } slo = cpu_ldl_data_ra(env, faddr, ra); shi = cpu_ldl_data_ra(env, faddr + 4, ra); dn = (uint64_t) shi << 32 | slo; *aa32_vfp_dreg(env, i / 2) = dn; } fpscr = cpu_ldl_data_ra(env, fptr + 0x40, ra); vfp_set_fpscr(env, fpscr); } env->v7m.control[M_REG_S] |= R_V7M_CONTROL_FPCA_MASK; } static bool v7m_push_stack(ARMCPU *cpu) { /* * Do the "set up stack frame" part of exception entry, * similar to pseudocode PushStack(). * Return true if we generate a derived exception (and so * should ignore further stack faults trying to process * that derived exception.) */ bool stacked_ok = true, limitviol = false; CPUARMState *env = &cpu->env; uint32_t xpsr = xpsr_read(env); uint32_t frameptr = env->regs[13]; ARMMMUIdx mmu_idx = arm_mmu_idx(env); uint32_t framesize; bool nsacr_cp10 = extract32(env->v7m.nsacr, 10, 1); if ((env->v7m.control[M_REG_S] & R_V7M_CONTROL_FPCA_MASK) && (env->v7m.secure || nsacr_cp10)) { if (env->v7m.secure && env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_TS_MASK) { framesize = 0xa8; } else { framesize = 0x68; } } else { framesize = 0x20; } /* Align stack pointer if the guest wants that */ if ((frameptr & 4) && (env->v7m.ccr[env->v7m.secure] & R_V7M_CCR_STKALIGN_MASK)) { frameptr -= 4; xpsr |= XPSR_SPREALIGN; } xpsr &= ~XPSR_SFPA; if (env->v7m.secure && (env->v7m.control[M_REG_S] & R_V7M_CONTROL_SFPA_MASK)) { xpsr |= XPSR_SFPA; } frameptr -= framesize; if (arm_feature(env, ARM_FEATURE_V8)) { uint32_t limit = v7m_sp_limit(env); if (frameptr < limit) { /* * Stack limit failure: set SP to the limit value, and generate * STKOF UsageFault. Stack pushes below the limit must not be * performed. It is IMPDEF whether pushes above the limit are * performed; we choose not to. */ qemu_log_mask(CPU_LOG_INT, "...STKOF during stacking\n"); env->v7m.cfsr[env->v7m.secure] |= R_V7M_CFSR_STKOF_MASK; armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE, env->v7m.secure); env->regs[13] = limit; /* * We won't try to perform any further memory accesses but * we must continue through the following code to check for * permission faults during FPU state preservation, and we * must update FPCCR if lazy stacking is enabled. */ limitviol = true; stacked_ok = false; } } /* * Write as much of the stack frame as we can. If we fail a stack * write this will result in a derived exception being pended * (which may be taken in preference to the one we started with * if it has higher priority). */ stacked_ok = stacked_ok && v7m_stack_write(cpu, frameptr, env->regs[0], mmu_idx, STACK_NORMAL) && v7m_stack_write(cpu, frameptr + 4, env->regs[1], mmu_idx, STACK_NORMAL) && v7m_stack_write(cpu, frameptr + 8, env->regs[2], mmu_idx, STACK_NORMAL) && v7m_stack_write(cpu, frameptr + 12, env->regs[3], mmu_idx, STACK_NORMAL) && v7m_stack_write(cpu, frameptr + 16, env->regs[12], mmu_idx, STACK_NORMAL) && v7m_stack_write(cpu, frameptr + 20, env->regs[14], mmu_idx, STACK_NORMAL) && v7m_stack_write(cpu, frameptr + 24, env->regs[15], mmu_idx, STACK_NORMAL) && v7m_stack_write(cpu, frameptr + 28, xpsr, mmu_idx, STACK_NORMAL); if (env->v7m.control[M_REG_S] & R_V7M_CONTROL_FPCA_MASK) { /* FPU is active, try to save its registers */ bool fpccr_s = env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_S_MASK; bool lspact = env->v7m.fpccr[fpccr_s] & R_V7M_FPCCR_LSPACT_MASK; if (lspact && arm_feature(env, ARM_FEATURE_M_SECURITY)) { qemu_log_mask(CPU_LOG_INT, "...SecureFault because LSPACT and FPCA both set\n"); env->v7m.sfsr |= R_V7M_SFSR_LSERR_MASK; armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_SECURE, false); } else if (!env->v7m.secure && !nsacr_cp10) { qemu_log_mask(CPU_LOG_INT, "...Secure UsageFault with CFSR.NOCP because " "NSACR.CP10 prevents stacking FP regs\n"); armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE, M_REG_S); env->v7m.cfsr[M_REG_S] |= R_V7M_CFSR_NOCP_MASK; } else { if (!(env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_LSPEN_MASK)) { /* Lazy stacking disabled, save registers now */ int i; bool cpacr_pass = v7m_cpacr_pass(env, env->v7m.secure, arm_current_el(env) != 0); if (stacked_ok && !cpacr_pass) { /* * Take UsageFault if CPACR forbids access. The pseudocode * here does a full CheckCPEnabled() but we know the NSACR * check can never fail as we have already handled that. */ qemu_log_mask(CPU_LOG_INT, "...UsageFault with CFSR.NOCP because " "CPACR.CP10 prevents stacking FP regs\n"); armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE, env->v7m.secure); env->v7m.cfsr[env->v7m.secure] |= R_V7M_CFSR_NOCP_MASK; stacked_ok = false; } for (i = 0; i < ((framesize == 0xa8) ? 32 : 16); i += 2) { uint64_t dn = *aa32_vfp_dreg(env, i / 2); uint32_t faddr = frameptr + 0x20 + 4 * i; uint32_t slo = extract64(dn, 0, 32); uint32_t shi = extract64(dn, 32, 32); if (i >= 16) { faddr += 8; /* skip the slot for the FPSCR */ } stacked_ok = stacked_ok && v7m_stack_write(cpu, faddr, slo, mmu_idx, STACK_NORMAL) && v7m_stack_write(cpu, faddr + 4, shi, mmu_idx, STACK_NORMAL); } stacked_ok = stacked_ok && v7m_stack_write(cpu, frameptr + 0x60, vfp_get_fpscr(env), mmu_idx, STACK_NORMAL); if (cpacr_pass) { for (i = 0; i < ((framesize == 0xa8) ? 32 : 16); i += 2) { *aa32_vfp_dreg(env, i / 2) = 0; } vfp_set_fpscr(env, 0); } } else { /* Lazy stacking enabled, save necessary info to stack later */ v7m_update_fpccr(env, frameptr + 0x20, true); } } } /* * If we broke a stack limit then SP was already updated earlier; * otherwise we update SP regardless of whether any of the stack * accesses failed or we took some other kind of fault. */ if (!limitviol) { env->regs[13] = frameptr; } return !stacked_ok; } static void do_v7m_exception_exit(ARMCPU *cpu) { CPUARMState *env = &cpu->env; uint32_t excret; uint32_t xpsr, xpsr_mask; bool ufault = false; bool sfault = false; bool return_to_sp_process; bool return_to_handler; bool rettobase = false; bool exc_secure = false; bool return_to_secure; bool ftype; bool restore_s16_s31; /* * If we're not in Handler mode then jumps to magic exception-exit * addresses don't have magic behaviour. However for the v8M * security extensions the magic secure-function-return has to * work in thread mode too, so to avoid doing an extra check in * the generated code we allow exception-exit magic to also cause the * internal exception and bring us here in thread mode. Correct code * will never try to do this (the following insn fetch will always * fault) so we the overhead of having taken an unnecessary exception * doesn't matter. */ if (!arm_v7m_is_handler_mode(env)) { return; } /* * In the spec pseudocode ExceptionReturn() is called directly * from BXWritePC() and gets the full target PC value including * bit zero. In QEMU's implementation we treat it as a normal * jump-to-register (which is then caught later on), and so split * the target value up between env->regs[15] and env->thumb in * gen_bx(). Reconstitute it. */ excret = env->regs[15]; if (env->thumb) { excret |= 1; } qemu_log_mask(CPU_LOG_INT, "Exception return: magic PC %" PRIx32 " previous exception %d\n", excret, env->v7m.exception); if ((excret & R_V7M_EXCRET_RES1_MASK) != R_V7M_EXCRET_RES1_MASK) { qemu_log_mask(LOG_GUEST_ERROR, "M profile: zero high bits in exception " "exit PC value 0x%" PRIx32 " are UNPREDICTABLE\n", excret); } ftype = excret & R_V7M_EXCRET_FTYPE_MASK; if (!arm_feature(env, ARM_FEATURE_VFP) && !ftype) { qemu_log_mask(LOG_GUEST_ERROR, "M profile: zero FTYPE in exception " "exit PC value 0x%" PRIx32 " is UNPREDICTABLE " "if FPU not present\n", excret); ftype = true; } if (arm_feature(env, ARM_FEATURE_M_SECURITY)) { /* * EXC_RETURN.ES validation check (R_SMFL). We must do this before * we pick which FAULTMASK to clear. */ if (!env->v7m.secure && ((excret & R_V7M_EXCRET_ES_MASK) || !(excret & R_V7M_EXCRET_DCRS_MASK))) { sfault = 1; /* For all other purposes, treat ES as 0 (R_HXSR) */ excret &= ~R_V7M_EXCRET_ES_MASK; } exc_secure = excret & R_V7M_EXCRET_ES_MASK; } if (env->v7m.exception != ARMV7M_EXCP_NMI) { /* * Auto-clear FAULTMASK on return from other than NMI. * If the security extension is implemented then this only * happens if the raw execution priority is >= 0; the * value of the ES bit in the exception return value indicates * which security state's faultmask to clear. (v8M ARM ARM R_KBNF.) */ if (arm_feature(env, ARM_FEATURE_M_SECURITY)) { if (armv7m_nvic_raw_execution_priority(env->nvic) >= 0) { env->v7m.faultmask[exc_secure] = 0; } } else { env->v7m.faultmask[M_REG_NS] = 0; } } switch (armv7m_nvic_complete_irq(env->nvic, env->v7m.exception, exc_secure)) { case -1: /* attempt to exit an exception that isn't active */ ufault = true; break; case 0: /* still an irq active now */ break; case 1: /* * We returned to base exception level, no nesting. * (In the pseudocode this is written using "NestedActivation != 1" * where we have 'rettobase == false'.) */ rettobase = true; break; default: g_assert_not_reached(); } return_to_handler = !(excret & R_V7M_EXCRET_MODE_MASK); return_to_sp_process = excret & R_V7M_EXCRET_SPSEL_MASK; return_to_secure = arm_feature(env, ARM_FEATURE_M_SECURITY) && (excret & R_V7M_EXCRET_S_MASK); if (arm_feature(env, ARM_FEATURE_V8)) { if (!arm_feature(env, ARM_FEATURE_M_SECURITY)) { /* * UNPREDICTABLE if S == 1 or DCRS == 0 or ES == 1 (R_XLCP); * we choose to take the UsageFault. */ if ((excret & R_V7M_EXCRET_S_MASK) || (excret & R_V7M_EXCRET_ES_MASK) || !(excret & R_V7M_EXCRET_DCRS_MASK)) { ufault = true; } } if (excret & R_V7M_EXCRET_RES0_MASK) { ufault = true; } } else { /* For v7M we only recognize certain combinations of the low bits */ switch (excret & 0xf) { case 1: /* Return to Handler */ break; case 13: /* Return to Thread using Process stack */ case 9: /* Return to Thread using Main stack */ /* * We only need to check NONBASETHRDENA for v7M, because in * v8M this bit does not exist (it is RES1). */ if (!rettobase && !(env->v7m.ccr[env->v7m.secure] & R_V7M_CCR_NONBASETHRDENA_MASK)) { ufault = true; } break; default: ufault = true; } } /* * Set CONTROL.SPSEL from excret.SPSEL. Since we're still in * Handler mode (and will be until we write the new XPSR.Interrupt * field) this does not switch around the current stack pointer. * We must do this before we do any kind of tailchaining, including * for the derived exceptions on integrity check failures, or we will * give the guest an incorrect EXCRET.SPSEL value on exception entry. */ write_v7m_control_spsel_for_secstate(env, return_to_sp_process, exc_secure); /* * Clear scratch FP values left in caller saved registers; this * must happen before any kind of tail chaining. */ if ((env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_CLRONRET_MASK) && (env->v7m.control[M_REG_S] & R_V7M_CONTROL_FPCA_MASK)) { if (env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_LSPACT_MASK) { env->v7m.sfsr |= R_V7M_SFSR_LSERR_MASK; armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_SECURE, false); qemu_log_mask(CPU_LOG_INT, "...taking SecureFault on existing " "stackframe: error during lazy state deactivation\n"); v7m_exception_taken(cpu, excret, true, false); return; } else { /* Clear s0..s15 and FPSCR */ int i; for (i = 0; i < 16; i += 2) { *aa32_vfp_dreg(env, i / 2) = 0; } vfp_set_fpscr(env, 0); } } if (sfault) { env->v7m.sfsr |= R_V7M_SFSR_INVER_MASK; armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_SECURE, false); qemu_log_mask(CPU_LOG_INT, "...taking SecureFault on existing " "stackframe: failed EXC_RETURN.ES validity check\n"); v7m_exception_taken(cpu, excret, true, false); return; } if (ufault) { /* * Bad exception return: instead of popping the exception * stack, directly take a usage fault on the current stack. */ env->v7m.cfsr[env->v7m.secure] |= R_V7M_CFSR_INVPC_MASK; armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE, env->v7m.secure); qemu_log_mask(CPU_LOG_INT, "...taking UsageFault on existing " "stackframe: failed exception return integrity check\n"); v7m_exception_taken(cpu, excret, true, false); return; } /* * Tailchaining: if there is currently a pending exception that * is high enough priority to preempt execution at the level we're * about to return to, then just directly take that exception now, * avoiding an unstack-and-then-stack. Note that now we have * deactivated the previous exception by calling armv7m_nvic_complete_irq() * our current execution priority is already the execution priority we are * returning to -- none of the state we would unstack or set based on * the EXCRET value affects it. */ if (armv7m_nvic_can_take_pending_exception(env->nvic)) { qemu_log_mask(CPU_LOG_INT, "...tailchaining to pending exception\n"); v7m_exception_taken(cpu, excret, true, false); return; } switch_v7m_security_state(env, return_to_secure); { /* * The stack pointer we should be reading the exception frame from * depends on bits in the magic exception return type value (and * for v8M isn't necessarily the stack pointer we will eventually * end up resuming execution with). Get a pointer to the location * in the CPU state struct where the SP we need is currently being * stored; we will use and modify it in place. * We use this limited C variable scope so we don't accidentally * use 'frame_sp_p' after we do something that makes it invalid. */ uint32_t *frame_sp_p = get_v7m_sp_ptr(env, return_to_secure, !return_to_handler, return_to_sp_process); uint32_t frameptr = *frame_sp_p; bool pop_ok = true; ARMMMUIdx mmu_idx; bool return_to_priv = return_to_handler || !(env->v7m.control[return_to_secure] & R_V7M_CONTROL_NPRIV_MASK); mmu_idx = arm_v7m_mmu_idx_for_secstate_and_priv(env, return_to_secure, return_to_priv); if (!QEMU_IS_ALIGNED(frameptr, 8) && arm_feature(env, ARM_FEATURE_V8)) { qemu_log_mask(LOG_GUEST_ERROR, "M profile exception return with non-8-aligned SP " "for destination state is UNPREDICTABLE\n"); } /* Do we need to pop callee-saved registers? */ if (return_to_secure && ((excret & R_V7M_EXCRET_ES_MASK) == 0 || (excret & R_V7M_EXCRET_DCRS_MASK) == 0)) { uint32_t actual_sig; pop_ok = v7m_stack_read(cpu, &actual_sig, frameptr, mmu_idx); if (pop_ok && v7m_integrity_sig(env, excret) != actual_sig) { /* Take a SecureFault on the current stack */ env->v7m.sfsr |= R_V7M_SFSR_INVIS_MASK; armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_SECURE, false); qemu_log_mask(CPU_LOG_INT, "...taking SecureFault on existing " "stackframe: failed exception return integrity " "signature check\n"); v7m_exception_taken(cpu, excret, true, false); return; } pop_ok = pop_ok && v7m_stack_read(cpu, &env->regs[4], frameptr + 0x8, mmu_idx) && v7m_stack_read(cpu, &env->regs[5], frameptr + 0xc, mmu_idx) && v7m_stack_read(cpu, &env->regs[6], frameptr + 0x10, mmu_idx) && v7m_stack_read(cpu, &env->regs[7], frameptr + 0x14, mmu_idx) && v7m_stack_read(cpu, &env->regs[8], frameptr + 0x18, mmu_idx) && v7m_stack_read(cpu, &env->regs[9], frameptr + 0x1c, mmu_idx) && v7m_stack_read(cpu, &env->regs[10], frameptr + 0x20, mmu_idx) && v7m_stack_read(cpu, &env->regs[11], frameptr + 0x24, mmu_idx); frameptr += 0x28; } /* Pop registers */ pop_ok = pop_ok && v7m_stack_read(cpu, &env->regs[0], frameptr, mmu_idx) && v7m_stack_read(cpu, &env->regs[1], frameptr + 0x4, mmu_idx) && v7m_stack_read(cpu, &env->regs[2], frameptr + 0x8, mmu_idx) && v7m_stack_read(cpu, &env->regs[3], frameptr + 0xc, mmu_idx) && v7m_stack_read(cpu, &env->regs[12], frameptr + 0x10, mmu_idx) && v7m_stack_read(cpu, &env->regs[14], frameptr + 0x14, mmu_idx) && v7m_stack_read(cpu, &env->regs[15], frameptr + 0x18, mmu_idx) && v7m_stack_read(cpu, &xpsr, frameptr + 0x1c, mmu_idx); if (!pop_ok) { /* * v7m_stack_read() pended a fault, so take it (as a tail * chained exception on the same stack frame) */ qemu_log_mask(CPU_LOG_INT, "...derived exception on unstacking\n"); v7m_exception_taken(cpu, excret, true, false); return; } /* * Returning from an exception with a PC with bit 0 set is defined * behaviour on v8M (bit 0 is ignored), but for v7M it was specified * to be UNPREDICTABLE. In practice actual v7M hardware seems to ignore * the lsbit, and there are several RTOSes out there which incorrectly * assume the r15 in the stack frame should be a Thumb-style "lsbit * indicates ARM/Thumb" value, so ignore the bit on v7M as well, but * complain about the badly behaved guest. */ if (env->regs[15] & 1) { env->regs[15] &= ~1U; if (!arm_feature(env, ARM_FEATURE_V8)) { qemu_log_mask(LOG_GUEST_ERROR, "M profile return from interrupt with misaligned " "PC is UNPREDICTABLE on v7M\n"); } } if (arm_feature(env, ARM_FEATURE_V8)) { /* * For v8M we have to check whether the xPSR exception field * matches the EXCRET value for return to handler/thread * before we commit to changing the SP and xPSR. */ bool will_be_handler = (xpsr & XPSR_EXCP) != 0; if (return_to_handler != will_be_handler) { /* * Take an INVPC UsageFault on the current stack. * By this point we will have switched to the security state * for the background state, so this UsageFault will target * that state. */ armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE, env->v7m.secure); env->v7m.cfsr[env->v7m.secure] |= R_V7M_CFSR_INVPC_MASK; qemu_log_mask(CPU_LOG_INT, "...taking UsageFault on existing " "stackframe: failed exception return integrity " "check\n"); v7m_exception_taken(cpu, excret, true, false); return; } } if (!ftype) { /* FP present and we need to handle it */ if (!return_to_secure && (env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_LSPACT_MASK)) { armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_SECURE, false); env->v7m.sfsr |= R_V7M_SFSR_LSERR_MASK; qemu_log_mask(CPU_LOG_INT, "...taking SecureFault on existing stackframe: " "Secure LSPACT set but exception return is " "not to secure state\n"); v7m_exception_taken(cpu, excret, true, false); return; } restore_s16_s31 = return_to_secure && (env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_TS_MASK); if (env->v7m.fpccr[return_to_secure] & R_V7M_FPCCR_LSPACT_MASK) { /* State in FPU is still valid, just clear LSPACT */ env->v7m.fpccr[return_to_secure] &= ~R_V7M_FPCCR_LSPACT_MASK; } else { int i; uint32_t fpscr; bool cpacr_pass, nsacr_pass; cpacr_pass = v7m_cpacr_pass(env, return_to_secure, return_to_priv); nsacr_pass = return_to_secure || extract32(env->v7m.nsacr, 10, 1); if (!cpacr_pass) { armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE, return_to_secure); env->v7m.cfsr[return_to_secure] |= R_V7M_CFSR_NOCP_MASK; qemu_log_mask(CPU_LOG_INT, "...taking UsageFault on existing " "stackframe: CPACR.CP10 prevents unstacking " "FP regs\n"); v7m_exception_taken(cpu, excret, true, false); return; } else if (!nsacr_pass) { armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE, true); env->v7m.cfsr[M_REG_S] |= R_V7M_CFSR_INVPC_MASK; qemu_log_mask(CPU_LOG_INT, "...taking Secure UsageFault on existing " "stackframe: NSACR.CP10 prevents unstacking " "FP regs\n"); v7m_exception_taken(cpu, excret, true, false); return; } for (i = 0; i < (restore_s16_s31 ? 32 : 16); i += 2) { uint32_t slo, shi; uint64_t dn; uint32_t faddr = frameptr + 0x20 + 4 * i; if (i >= 16) { faddr += 8; /* Skip the slot for the FPSCR */ } pop_ok = pop_ok && v7m_stack_read(cpu, &slo, faddr, mmu_idx) && v7m_stack_read(cpu, &shi, faddr + 4, mmu_idx); if (!pop_ok) { break; } dn = (uint64_t)shi << 32 | slo; *aa32_vfp_dreg(env, i / 2) = dn; } pop_ok = pop_ok && v7m_stack_read(cpu, &fpscr, frameptr + 0x60, mmu_idx); if (pop_ok) { vfp_set_fpscr(env, fpscr); } if (!pop_ok) { /* * These regs are 0 if security extension present; * otherwise merely UNKNOWN. We zero always. */ for (i = 0; i < (restore_s16_s31 ? 32 : 16); i += 2) { *aa32_vfp_dreg(env, i / 2) = 0; } vfp_set_fpscr(env, 0); } } } env->v7m.control[M_REG_S] = FIELD_DP32(env->v7m.control[M_REG_S], V7M_CONTROL, FPCA, !ftype); /* Commit to consuming the stack frame */ frameptr += 0x20; if (!ftype) { frameptr += 0x48; if (restore_s16_s31) { frameptr += 0x40; } } /* * Undo stack alignment (the SPREALIGN bit indicates that the original * pre-exception SP was not 8-aligned and we added a padding word to * align it, so we undo this by ORing in the bit that increases it * from the current 8-aligned value to the 8-unaligned value. (Adding 4 * would work too but a logical OR is how the pseudocode specifies it.) */ if (xpsr & XPSR_SPREALIGN) { frameptr |= 4; } *frame_sp_p = frameptr; } xpsr_mask = ~(XPSR_SPREALIGN | XPSR_SFPA); if (!arm_feature(env, ARM_FEATURE_THUMB_DSP)) { xpsr_mask &= ~XPSR_GE; } /* This xpsr_write() will invalidate frame_sp_p as it may switch stack */ xpsr_write(env, xpsr, xpsr_mask); if (env->v7m.secure) { bool sfpa = xpsr & XPSR_SFPA; env->v7m.control[M_REG_S] = FIELD_DP32(env->v7m.control[M_REG_S], V7M_CONTROL, SFPA, sfpa); } /* * The restored xPSR exception field will be zero if we're * resuming in Thread mode. If that doesn't match what the * exception return excret specified then this is a UsageFault. * v7M requires we make this check here; v8M did it earlier. */ if (return_to_handler != arm_v7m_is_handler_mode(env)) { /* * Take an INVPC UsageFault by pushing the stack again; * we know we're v7M so this is never a Secure UsageFault. */ bool ignore_stackfaults; assert(!arm_feature(env, ARM_FEATURE_V8)); armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE, false); env->v7m.cfsr[env->v7m.secure] |= R_V7M_CFSR_INVPC_MASK; ignore_stackfaults = v7m_push_stack(cpu); qemu_log_mask(CPU_LOG_INT, "...taking UsageFault on new stackframe: " "failed exception return integrity check\n"); v7m_exception_taken(cpu, excret, false, ignore_stackfaults); return; } /* Otherwise, we have a successful exception exit. */ arm_clear_exclusive(env); arm_rebuild_hflags(env); qemu_log_mask(CPU_LOG_INT, "...successful exception return\n"); } static bool do_v7m_function_return(ARMCPU *cpu) { /* * v8M security extensions magic function return. * We may either: * (1) throw an exception (longjump) * (2) return true if we successfully handled the function return * (3) return false if we failed a consistency check and have * pended a UsageFault that needs to be taken now * * At this point the magic return value is split between env->regs[15] * and env->thumb. We don't bother to reconstitute it because we don't * need it (all values are handled the same way). */ CPUARMState *env = &cpu->env; uint32_t newpc, newpsr, newpsr_exc; qemu_log_mask(CPU_LOG_INT, "...really v7M secure function return\n"); { bool threadmode, spsel; TCGMemOpIdx oi; ARMMMUIdx mmu_idx; uint32_t *frame_sp_p; uint32_t frameptr; /* Pull the return address and IPSR from the Secure stack */ threadmode = !arm_v7m_is_handler_mode(env); spsel = env->v7m.control[M_REG_S] & R_V7M_CONTROL_SPSEL_MASK; frame_sp_p = get_v7m_sp_ptr(env, true, threadmode, spsel); frameptr = *frame_sp_p; /* * These loads may throw an exception (for MPU faults). We want to * do them as secure, so work out what MMU index that is. */ mmu_idx = arm_v7m_mmu_idx_for_secstate(env, true); oi = make_memop_idx(MO_LE, arm_to_core_mmu_idx(mmu_idx)); newpc = helper_le_ldul_mmu(env, frameptr, oi, 0); newpsr = helper_le_ldul_mmu(env, frameptr + 4, oi, 0); /* Consistency checks on new IPSR */ newpsr_exc = newpsr & XPSR_EXCP; if (!((env->v7m.exception == 0 && newpsr_exc == 0) || (env->v7m.exception == 1 && newpsr_exc != 0))) { /* Pend the fault and tell our caller to take it */ env->v7m.cfsr[env->v7m.secure] |= R_V7M_CFSR_INVPC_MASK; armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE, env->v7m.secure); qemu_log_mask(CPU_LOG_INT, "...taking INVPC UsageFault: " "IPSR consistency check failed\n"); return false; } *frame_sp_p = frameptr + 8; } /* This invalidates frame_sp_p */ switch_v7m_security_state(env, true); env->v7m.exception = newpsr_exc; env->v7m.control[M_REG_S] &= ~R_V7M_CONTROL_SFPA_MASK; if (newpsr & XPSR_SFPA) { env->v7m.control[M_REG_S] |= R_V7M_CONTROL_SFPA_MASK; } xpsr_write(env, 0, XPSR_IT); env->thumb = newpc & 1; env->regs[15] = newpc & ~1; arm_rebuild_hflags(env); qemu_log_mask(CPU_LOG_INT, "...function return successful\n"); return true; } static bool v7m_read_half_insn(ARMCPU *cpu, ARMMMUIdx mmu_idx, uint32_t addr, uint16_t *insn) { /* * Load a 16-bit portion of a v7M instruction, returning true on success, * or false on failure (in which case we will have pended the appropriate * exception). * We need to do the instruction fetch's MPU and SAU checks * like this because there is no MMU index that would allow * doing the load with a single function call. Instead we must * first check that the security attributes permit the load * and that they don't mismatch on the two halves of the instruction, * and then we do the load as a secure load (ie using the security * attributes of the address, not the CPU, as architecturally required). */ CPUState *cs = CPU(cpu); CPUARMState *env = &cpu->env; V8M_SAttributes sattrs = {}; MemTxAttrs attrs = {}; ARMMMUFaultInfo fi = {}; MemTxResult txres; target_ulong page_size; hwaddr physaddr; int prot; v8m_security_lookup(env, addr, MMU_INST_FETCH, mmu_idx, &sattrs); if (!sattrs.nsc || sattrs.ns) { /* * This must be the second half of the insn, and it straddles a * region boundary with the second half not being S&NSC. */ env->v7m.sfsr |= R_V7M_SFSR_INVEP_MASK; armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_SECURE, false); qemu_log_mask(CPU_LOG_INT, "...really SecureFault with SFSR.INVEP\n"); return false; } if (get_phys_addr(env, addr, MMU_INST_FETCH, mmu_idx, &physaddr, &attrs, &prot, &page_size, &fi, NULL)) { /* the MPU lookup failed */ env->v7m.cfsr[env->v7m.secure] |= R_V7M_CFSR_IACCVIOL_MASK; armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_MEM, env->v7m.secure); qemu_log_mask(CPU_LOG_INT, "...really MemManage with CFSR.IACCVIOL\n"); return false; } *insn = address_space_lduw_le(arm_addressspace(cs, attrs), physaddr, attrs, &txres); if (txres != MEMTX_OK) { env->v7m.cfsr[M_REG_NS] |= R_V7M_CFSR_IBUSERR_MASK; armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_BUS, false); qemu_log_mask(CPU_LOG_INT, "...really BusFault with CFSR.IBUSERR\n"); return false; } return true; } static bool v7m_handle_execute_nsc(ARMCPU *cpu) { /* * Check whether this attempt to execute code in a Secure & NS-Callable * memory region is for an SG instruction; if so, then emulate the * effect of the SG instruction and return true. Otherwise pend * the correct kind of exception and return false. */ CPUARMState *env = &cpu->env; ARMMMUIdx mmu_idx; uint16_t insn; /* * We should never get here unless get_phys_addr_pmsav8() caused * an exception for NS executing in S&NSC memory. */ assert(!env->v7m.secure); assert(arm_feature(env, ARM_FEATURE_M_SECURITY)); /* We want to do the MPU lookup as secure; work out what mmu_idx that is */ mmu_idx = arm_v7m_mmu_idx_for_secstate(env, true); if (!v7m_read_half_insn(cpu, mmu_idx, env->regs[15], &insn)) { return false; } if (!env->thumb) { goto gen_invep; } if (insn != 0xe97f) { /* * Not an SG instruction first half (we choose the IMPDEF * early-SG-check option). */ goto gen_invep; } if (!v7m_read_half_insn(cpu, mmu_idx, env->regs[15] + 2, &insn)) { return false; } if (insn != 0xe97f) { /* * Not an SG instruction second half (yes, both halves of the SG * insn have the same hex value) */ goto gen_invep; } /* * OK, we have confirmed that we really have an SG instruction. * We know we're NS in S memory so don't need to repeat those checks. */ qemu_log_mask(CPU_LOG_INT, "...really an SG instruction at 0x%08" PRIx32 ", executing it\n", env->regs[15]); env->regs[14] &= ~1; env->v7m.control[M_REG_S] &= ~R_V7M_CONTROL_SFPA_MASK; switch_v7m_security_state(env, true); xpsr_write(env, 0, XPSR_IT); env->regs[15] += 4; arm_rebuild_hflags(env); return true; gen_invep: env->v7m.sfsr |= R_V7M_SFSR_INVEP_MASK; armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_SECURE, false); qemu_log_mask(CPU_LOG_INT, "...really SecureFault with SFSR.INVEP\n"); return false; } void arm_v7m_cpu_do_interrupt(CPUState *cs) { ARMCPU *cpu = ARM_CPU(cs); CPUARMState *env = &cpu->env; uint32_t lr; bool ignore_stackfaults; arm_log_exception(cs->exception_index); /* * For exceptions we just mark as pending on the NVIC, and let that * handle it. */ switch (cs->exception_index) { case EXCP_UDEF: armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE, env->v7m.secure); env->v7m.cfsr[env->v7m.secure] |= R_V7M_CFSR_UNDEFINSTR_MASK; break; case EXCP_NOCP: { /* * NOCP might be directed to something other than the current * security state if this fault is because of NSACR; we indicate * the target security state using exception.target_el. */ int target_secstate; if (env->exception.target_el == 3) { target_secstate = M_REG_S; } else { target_secstate = env->v7m.secure; } armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE, target_secstate); env->v7m.cfsr[target_secstate] |= R_V7M_CFSR_NOCP_MASK; break; } case EXCP_INVSTATE: armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE, env->v7m.secure); env->v7m.cfsr[env->v7m.secure] |= R_V7M_CFSR_INVSTATE_MASK; break; case EXCP_STKOF: armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE, env->v7m.secure); env->v7m.cfsr[env->v7m.secure] |= R_V7M_CFSR_STKOF_MASK; break; case EXCP_LSERR: armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_SECURE, false); env->v7m.sfsr |= R_V7M_SFSR_LSERR_MASK; break; case EXCP_UNALIGNED: armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE, env->v7m.secure); env->v7m.cfsr[env->v7m.secure] |= R_V7M_CFSR_UNALIGNED_MASK; break; case EXCP_SWI: /* The PC already points to the next instruction. */ armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_SVC, env->v7m.secure); break; case EXCP_PREFETCH_ABORT: case EXCP_DATA_ABORT: /* * Note that for M profile we don't have a guest facing FSR, but * the env->exception.fsr will be populated by the code that * raises the fault, in the A profile short-descriptor format. */ switch (env->exception.fsr & 0xf) { case M_FAKE_FSR_NSC_EXEC: /* * Exception generated when we try to execute code at an address * which is marked as Secure & Non-Secure Callable and the CPU * is in the Non-Secure state. The only instruction which can * be executed like this is SG (and that only if both halves of * the SG instruction have the same security attributes.) * Everything else must generate an INVEP SecureFault, so we * emulate the SG instruction here. */ if (v7m_handle_execute_nsc(cpu)) { return; } break; case M_FAKE_FSR_SFAULT: /* * Various flavours of SecureFault for attempts to execute or * access data in the wrong security state. */ switch (cs->exception_index) { case EXCP_PREFETCH_ABORT: if (env->v7m.secure) { env->v7m.sfsr |= R_V7M_SFSR_INVTRAN_MASK; qemu_log_mask(CPU_LOG_INT, "...really SecureFault with SFSR.INVTRAN\n"); } else { env->v7m.sfsr |= R_V7M_SFSR_INVEP_MASK; qemu_log_mask(CPU_LOG_INT, "...really SecureFault with SFSR.INVEP\n"); } break; case EXCP_DATA_ABORT: /* This must be an NS access to S memory */ env->v7m.sfsr |= R_V7M_SFSR_AUVIOL_MASK; qemu_log_mask(CPU_LOG_INT, "...really SecureFault with SFSR.AUVIOL\n"); break; } armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_SECURE, false); break; case 0x8: /* External Abort */ switch (cs->exception_index) { case EXCP_PREFETCH_ABORT: env->v7m.cfsr[M_REG_NS] |= R_V7M_CFSR_IBUSERR_MASK; qemu_log_mask(CPU_LOG_INT, "...with CFSR.IBUSERR\n"); break; case EXCP_DATA_ABORT: env->v7m.cfsr[M_REG_NS] |= (R_V7M_CFSR_PRECISERR_MASK | R_V7M_CFSR_BFARVALID_MASK); env->v7m.bfar = env->exception.vaddress; qemu_log_mask(CPU_LOG_INT, "...with CFSR.PRECISERR and BFAR 0x%x\n", env->v7m.bfar); break; } armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_BUS, false); break; default: /* * All other FSR values are either MPU faults or "can't happen * for M profile" cases. */ switch (cs->exception_index) { case EXCP_PREFETCH_ABORT: env->v7m.cfsr[env->v7m.secure] |= R_V7M_CFSR_IACCVIOL_MASK; qemu_log_mask(CPU_LOG_INT, "...with CFSR.IACCVIOL\n"); break; case EXCP_DATA_ABORT: env->v7m.cfsr[env->v7m.secure] |= (R_V7M_CFSR_DACCVIOL_MASK | R_V7M_CFSR_MMARVALID_MASK); env->v7m.mmfar[env->v7m.secure] = env->exception.vaddress; qemu_log_mask(CPU_LOG_INT, "...with CFSR.DACCVIOL and MMFAR 0x%x\n", env->v7m.mmfar[env->v7m.secure]); break; } armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_MEM, env->v7m.secure); break; } break; case EXCP_SEMIHOST: qemu_log_mask(CPU_LOG_INT, "...handling as semihosting call 0x%x\n", env->regs[0]); env->regs[0] = do_arm_semihosting(env); env->regs[15] += env->thumb ? 2 : 4; return; case EXCP_BKPT: armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_DEBUG, false); break; case EXCP_IRQ: break; case EXCP_EXCEPTION_EXIT: if (env->regs[15] < EXC_RETURN_MIN_MAGIC) { /* Must be v8M security extension function return */ assert(env->regs[15] >= FNC_RETURN_MIN_MAGIC); assert(arm_feature(env, ARM_FEATURE_M_SECURITY)); if (do_v7m_function_return(cpu)) { return; } } else { do_v7m_exception_exit(cpu); return; } break; case EXCP_LAZYFP: /* * We already pended the specific exception in the NVIC in the * v7m_preserve_fp_state() helper function. */ break; default: cpu_abort(cs, "Unhandled exception 0x%x\n", cs->exception_index); return; /* Never happens. Keep compiler happy. */ } if (arm_feature(env, ARM_FEATURE_V8)) { lr = R_V7M_EXCRET_RES1_MASK | R_V7M_EXCRET_DCRS_MASK; /* * The S bit indicates whether we should return to Secure * or NonSecure (ie our current state). * The ES bit indicates whether we're taking this exception * to Secure or NonSecure (ie our target state). We set it * later, in v7m_exception_taken(). * The SPSEL bit is also set in v7m_exception_taken() for v8M. * This corresponds to the ARM ARM pseudocode for v8M setting * some LR bits in PushStack() and some in ExceptionTaken(); * the distinction matters for the tailchain cases where we * can take an exception without pushing the stack. */ if (env->v7m.secure) { lr |= R_V7M_EXCRET_S_MASK; } } else { lr = R_V7M_EXCRET_RES1_MASK | R_V7M_EXCRET_S_MASK | R_V7M_EXCRET_DCRS_MASK | R_V7M_EXCRET_ES_MASK; if (env->v7m.control[M_REG_NS] & R_V7M_CONTROL_SPSEL_MASK) { lr |= R_V7M_EXCRET_SPSEL_MASK; } } if (!(env->v7m.control[M_REG_S] & R_V7M_CONTROL_FPCA_MASK)) { lr |= R_V7M_EXCRET_FTYPE_MASK; } if (!arm_v7m_is_handler_mode(env)) { lr |= R_V7M_EXCRET_MODE_MASK; } ignore_stackfaults = v7m_push_stack(cpu); v7m_exception_taken(cpu, lr, false, ignore_stackfaults); } uint32_t HELPER(v7m_mrs)(CPUARMState *env, uint32_t reg) { unsigned el = arm_current_el(env); /* First handle registers which unprivileged can read */ switch (reg) { case 0 ... 7: /* xPSR sub-fields */ return v7m_mrs_xpsr(env, reg, el); case 20: /* CONTROL */ return v7m_mrs_control(env, env->v7m.secure); case 0x94: /* CONTROL_NS */ /* * We have to handle this here because unprivileged Secure code * can read the NS CONTROL register. */ if (!env->v7m.secure) { return 0; } return env->v7m.control[M_REG_NS] | (env->v7m.control[M_REG_S] & R_V7M_CONTROL_FPCA_MASK); } if (el == 0) { return 0; /* unprivileged reads others as zero */ } if (arm_feature(env, ARM_FEATURE_M_SECURITY)) { switch (reg) { case 0x88: /* MSP_NS */ if (!env->v7m.secure) { return 0; } return env->v7m.other_ss_msp; case 0x89: /* PSP_NS */ if (!env->v7m.secure) { return 0; } return env->v7m.other_ss_psp; case 0x8a: /* MSPLIM_NS */ if (!env->v7m.secure) { return 0; } return env->v7m.msplim[M_REG_NS]; case 0x8b: /* PSPLIM_NS */ if (!env->v7m.secure) { return 0; } return env->v7m.psplim[M_REG_NS]; case 0x90: /* PRIMASK_NS */ if (!env->v7m.secure) { return 0; } return env->v7m.primask[M_REG_NS]; case 0x91: /* BASEPRI_NS */ if (!env->v7m.secure) { return 0; } return env->v7m.basepri[M_REG_NS]; case 0x93: /* FAULTMASK_NS */ if (!env->v7m.secure) { return 0; } return env->v7m.faultmask[M_REG_NS]; case 0x98: /* SP_NS */ { /* * This gives the non-secure SP selected based on whether we're * currently in handler mode or not, using the NS CONTROL.SPSEL. */ bool spsel = env->v7m.control[M_REG_NS] & R_V7M_CONTROL_SPSEL_MASK; if (!env->v7m.secure) { return 0; } if (!arm_v7m_is_handler_mode(env) && spsel) { return env->v7m.other_ss_psp; } else { return env->v7m.other_ss_msp; } } default: break; } } switch (reg) { case 8: /* MSP */ return v7m_using_psp(env) ? env->v7m.other_sp : env->regs[13]; case 9: /* PSP */ return v7m_using_psp(env) ? env->regs[13] : env->v7m.other_sp; case 10: /* MSPLIM */ if (!arm_feature(env, ARM_FEATURE_V8)) { goto bad_reg; } return env->v7m.msplim[env->v7m.secure]; case 11: /* PSPLIM */ if (!arm_feature(env, ARM_FEATURE_V8)) { goto bad_reg; } return env->v7m.psplim[env->v7m.secure]; case 16: /* PRIMASK */ return env->v7m.primask[env->v7m.secure]; case 17: /* BASEPRI */ case 18: /* BASEPRI_MAX */ return env->v7m.basepri[env->v7m.secure]; case 19: /* FAULTMASK */ return env->v7m.faultmask[env->v7m.secure]; default: bad_reg: qemu_log_mask(LOG_GUEST_ERROR, "Attempt to read unknown special" " register %d\n", reg); return 0; } } void HELPER(v7m_msr)(CPUARMState *env, uint32_t maskreg, uint32_t val) { /* * We're passed bits [11..0] of the instruction; extract * SYSm and the mask bits. * Invalid combinations of SYSm and mask are UNPREDICTABLE; * we choose to treat them as if the mask bits were valid. * NB that the pseudocode 'mask' variable is bits [11..10], * whereas ours is [11..8]. */ uint32_t mask = extract32(maskreg, 8, 4); uint32_t reg = extract32(maskreg, 0, 8); int cur_el = arm_current_el(env); if (cur_el == 0 && reg > 7 && reg != 20) { /* * only xPSR sub-fields and CONTROL.SFPA may be written by * unprivileged code */ return; } if (arm_feature(env, ARM_FEATURE_M_SECURITY)) { switch (reg) { case 0x88: /* MSP_NS */ if (!env->v7m.secure) { return; } env->v7m.other_ss_msp = val; return; case 0x89: /* PSP_NS */ if (!env->v7m.secure) { return; } env->v7m.other_ss_psp = val; return; case 0x8a: /* MSPLIM_NS */ if (!env->v7m.secure) { return; } env->v7m.msplim[M_REG_NS] = val & ~7; return; case 0x8b: /* PSPLIM_NS */ if (!env->v7m.secure) { return; } env->v7m.psplim[M_REG_NS] = val & ~7; return; case 0x90: /* PRIMASK_NS */ if (!env->v7m.secure) { return; } env->v7m.primask[M_REG_NS] = val & 1; return; case 0x91: /* BASEPRI_NS */ if (!env->v7m.secure || !arm_feature(env, ARM_FEATURE_M_MAIN)) { return; } env->v7m.basepri[M_REG_NS] = val & 0xff; return; case 0x93: /* FAULTMASK_NS */ if (!env->v7m.secure || !arm_feature(env, ARM_FEATURE_M_MAIN)) { return; } env->v7m.faultmask[M_REG_NS] = val & 1; return; case 0x94: /* CONTROL_NS */ if (!env->v7m.secure) { return; } write_v7m_control_spsel_for_secstate(env, val & R_V7M_CONTROL_SPSEL_MASK, M_REG_NS); if (arm_feature(env, ARM_FEATURE_M_MAIN)) { env->v7m.control[M_REG_NS] &= ~R_V7M_CONTROL_NPRIV_MASK; env->v7m.control[M_REG_NS] |= val & R_V7M_CONTROL_NPRIV_MASK; } /* * SFPA is RAZ/WI from NS. FPCA is RO if NSACR.CP10 == 0, * RES0 if the FPU is not present, and is stored in the S bank */ if (arm_feature(env, ARM_FEATURE_VFP) && extract32(env->v7m.nsacr, 10, 1)) { env->v7m.control[M_REG_S] &= ~R_V7M_CONTROL_FPCA_MASK; env->v7m.control[M_REG_S] |= val & R_V7M_CONTROL_FPCA_MASK; } return; case 0x98: /* SP_NS */ { /* * This gives the non-secure SP selected based on whether we're * currently in handler mode or not, using the NS CONTROL.SPSEL. */ bool spsel = env->v7m.control[M_REG_NS] & R_V7M_CONTROL_SPSEL_MASK; bool is_psp = !arm_v7m_is_handler_mode(env) && spsel; uint32_t limit; if (!env->v7m.secure) { return; } limit = is_psp ? env->v7m.psplim[false] : env->v7m.msplim[false]; if (val < limit) { CPUState *cs = env_cpu(env); cpu_restore_state(cs, GETPC(), true); raise_exception(env, EXCP_STKOF, 0, 1); } if (is_psp) { env->v7m.other_ss_psp = val; } else { env->v7m.other_ss_msp = val; } return; } default: break; } } switch (reg) { case 0 ... 7: /* xPSR sub-fields */ v7m_msr_xpsr(env, mask, reg, val); break; case 8: /* MSP */ if (v7m_using_psp(env)) { env->v7m.other_sp = val; } else { env->regs[13] = val; } break; case 9: /* PSP */ if (v7m_using_psp(env)) { env->regs[13] = val; } else { env->v7m.other_sp = val; } break; case 10: /* MSPLIM */ if (!arm_feature(env, ARM_FEATURE_V8)) { goto bad_reg; } env->v7m.msplim[env->v7m.secure] = val & ~7; break; case 11: /* PSPLIM */ if (!arm_feature(env, ARM_FEATURE_V8)) { goto bad_reg; } env->v7m.psplim[env->v7m.secure] = val & ~7; break; case 16: /* PRIMASK */ env->v7m.primask[env->v7m.secure] = val & 1; break; case 17: /* BASEPRI */ if (!arm_feature(env, ARM_FEATURE_M_MAIN)) { goto bad_reg; } env->v7m.basepri[env->v7m.secure] = val & 0xff; break; case 18: /* BASEPRI_MAX */ if (!arm_feature(env, ARM_FEATURE_M_MAIN)) { goto bad_reg; } val &= 0xff; if (val != 0 && (val < env->v7m.basepri[env->v7m.secure] || env->v7m.basepri[env->v7m.secure] == 0)) { env->v7m.basepri[env->v7m.secure] = val; } break; case 19: /* FAULTMASK */ if (!arm_feature(env, ARM_FEATURE_M_MAIN)) { goto bad_reg; } env->v7m.faultmask[env->v7m.secure] = val & 1; break; case 20: /* CONTROL */ /* * Writing to the SPSEL bit only has an effect if we are in * thread mode; other bits can be updated by any privileged code. * write_v7m_control_spsel() deals with updating the SPSEL bit in * env->v7m.control, so we only need update the others. * For v7M, we must just ignore explicit writes to SPSEL in handler * mode; for v8M the write is permitted but will have no effect. * All these bits are writes-ignored from non-privileged code, * except for SFPA. */ if (cur_el > 0 && (arm_feature(env, ARM_FEATURE_V8) || !arm_v7m_is_handler_mode(env))) { write_v7m_control_spsel(env, (val & R_V7M_CONTROL_SPSEL_MASK) != 0); } if (cur_el > 0 && arm_feature(env, ARM_FEATURE_M_MAIN)) { env->v7m.control[env->v7m.secure] &= ~R_V7M_CONTROL_NPRIV_MASK; env->v7m.control[env->v7m.secure] |= val & R_V7M_CONTROL_NPRIV_MASK; } if (arm_feature(env, ARM_FEATURE_VFP)) { /* * SFPA is RAZ/WI from NS or if no FPU. * FPCA is RO if NSACR.CP10 == 0, RES0 if the FPU is not present. * Both are stored in the S bank. */ if (env->v7m.secure) { env->v7m.control[M_REG_S] &= ~R_V7M_CONTROL_SFPA_MASK; env->v7m.control[M_REG_S] |= val & R_V7M_CONTROL_SFPA_MASK; } if (cur_el > 0 && (env->v7m.secure || !arm_feature(env, ARM_FEATURE_M_SECURITY) || extract32(env->v7m.nsacr, 10, 1))) { env->v7m.control[M_REG_S] &= ~R_V7M_CONTROL_FPCA_MASK; env->v7m.control[M_REG_S] |= val & R_V7M_CONTROL_FPCA_MASK; } } break; default: bad_reg: qemu_log_mask(LOG_GUEST_ERROR, "Attempt to write unknown special" " register %d\n", reg); return; } } uint32_t HELPER(v7m_tt)(CPUARMState *env, uint32_t addr, uint32_t op) { /* Implement the TT instruction. op is bits [7:6] of the insn. */ bool forceunpriv = op & 1; bool alt = op & 2; V8M_SAttributes sattrs = {}; uint32_t tt_resp; bool r, rw, nsr, nsrw, mrvalid; int prot; ARMMMUFaultInfo fi = {}; MemTxAttrs attrs = {}; hwaddr phys_addr; ARMMMUIdx mmu_idx; uint32_t mregion; bool targetpriv; bool targetsec = env->v7m.secure; bool is_subpage; /* * Work out what the security state and privilege level we're * interested in is... */ if (alt) { targetsec = !targetsec; } if (forceunpriv) { targetpriv = false; } else { targetpriv = arm_v7m_is_handler_mode(env) || !(env->v7m.control[targetsec] & R_V7M_CONTROL_NPRIV_MASK); } /* ...and then figure out which MMU index this is */ mmu_idx = arm_v7m_mmu_idx_for_secstate_and_priv(env, targetsec, targetpriv); /* * We know that the MPU and SAU don't care about the access type * for our purposes beyond that we don't want to claim to be * an insn fetch, so we arbitrarily call this a read. */ /* * MPU region info only available for privileged or if * inspecting the other MPU state. */ if (arm_current_el(env) != 0 || alt) { /* We can ignore the return value as prot is always set */ pmsav8_mpu_lookup(env, addr, MMU_DATA_LOAD, mmu_idx, &phys_addr, &attrs, &prot, &is_subpage, &fi, &mregion); if (mregion == -1) { mrvalid = false; mregion = 0; } else { mrvalid = true; } r = prot & PAGE_READ; rw = prot & PAGE_WRITE; } else { r = false; rw = false; mrvalid = false; mregion = 0; } if (env->v7m.secure) { v8m_security_lookup(env, addr, MMU_DATA_LOAD, mmu_idx, &sattrs); nsr = sattrs.ns && r; nsrw = sattrs.ns && rw; } else { sattrs.ns = true; nsr = false; nsrw = false; } tt_resp = (sattrs.iregion << 24) | (sattrs.irvalid << 23) | ((!sattrs.ns) << 22) | (nsrw << 21) | (nsr << 20) | (rw << 19) | (r << 18) | (sattrs.srvalid << 17) | (mrvalid << 16) | (sattrs.sregion << 8) | mregion; return tt_resp; } #endif /* !CONFIG_USER_ONLY */ ARMMMUIdx arm_v7m_mmu_idx_all(CPUARMState *env, bool secstate, bool priv, bool negpri) { ARMMMUIdx mmu_idx = ARM_MMU_IDX_M; if (priv) { mmu_idx |= ARM_MMU_IDX_M_PRIV; } if (negpri) { mmu_idx |= ARM_MMU_IDX_M_NEGPRI; } if (secstate) { mmu_idx |= ARM_MMU_IDX_M_S; } return mmu_idx; } ARMMMUIdx arm_v7m_mmu_idx_for_secstate_and_priv(CPUARMState *env, bool secstate, bool priv) { bool negpri = armv7m_nvic_neg_prio_requested(env->nvic, secstate); return arm_v7m_mmu_idx_all(env, secstate, priv, negpri); } /* Return the MMU index for a v7M CPU in the specified security state */ ARMMMUIdx arm_v7m_mmu_idx_for_secstate(CPUARMState *env, bool secstate) { bool priv = arm_current_el(env) != 0; return arm_v7m_mmu_idx_for_secstate_and_priv(env, secstate, priv); }