diff options
Diffstat (limited to 'target/arm/helper.c')
-rw-r--r-- | target/arm/helper.c | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/target/arm/helper.c b/target/arm/helper.c index 41531390..b11f8aa 100644 --- a/target/arm/helper.c +++ b/target/arm/helper.c @@ -7378,6 +7378,12 @@ void HELPER(v7m_blxns)(CPUARMState *env, uint32_t dest) 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(); +} + uint32_t HELPER(v7m_tt)(CPUARMState *env, uint32_t addr, uint32_t op) { /* The TT instructions can be used by unprivileged code, but in @@ -7737,6 +7743,97 @@ pend_fault: 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 = arm_env_get_cpu(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 @@ -9062,6 +9159,7 @@ static void arm_log_exception(int idx) [EXCP_NOCP] = "v7M NOCP UsageFault", [EXCP_INVSTATE] = "v7M INVSTATE UsageFault", [EXCP_STKOF] = "v8M STKOF UsageFault", + [EXCP_LAZYFP] = "v7M exception during lazy FP stacking", }; if (idx >= 0 && idx < ARRAY_SIZE(excnames)) { @@ -9355,6 +9453,12 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs) 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. */ @@ -13483,6 +13587,14 @@ void cpu_get_tb_cpu_state(CPUARMState *env, target_ulong *pc, flags = FIELD_DP32(flags, TBFLAG_A32, NEW_FP_CTXT_NEEDED, 1); } + if (arm_feature(env, ARM_FEATURE_M)) { + bool is_secure = env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_S_MASK; + + if (env->v7m.fpccr[is_secure] & R_V7M_FPCCR_LSPACT_MASK) { + flags = FIELD_DP32(flags, TBFLAG_A32, LSPACT, 1); + } + } + *pflags = flags; *cs_base = 0; } |