Initial import of abandoned HQEMU version 2.5.2HEADmaster

1 files changed, 1016 insertions, 0 deletions

diff --git a/src/target-arm/op_helper.c b/src/target-arm/op_helper.c
new file mode 100644
index 0000000..fdea907
--- /dev/null
+++ b/src/target-arm/op_helper.c
@@ -0,0 +1,1016 @@
+/*
+ *  ARM helper routines
+ *
+ *  Copyright (c) 2005-2007 CodeSourcery, LLC
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+#include "cpu.h"
+#include "exec/helper-proto.h"
+#include "internals.h"
+#include "exec/cpu_ldst.h"
+
+#define SIGNBIT (uint32_t)0x80000000
+#define SIGNBIT64 ((uint64_t)1 << 63)
+
+static void raise_exception(CPUARMState *env, uint32_t excp,
+                            uint32_t syndrome, uint32_t target_el)
+{
+    CPUState *cs = CPU(arm_env_get_cpu(env));
+
+    assert(!excp_is_internal(excp));
+    cs->exception_index = excp;
+    env->exception.syndrome = syndrome;
+    env->exception.target_el = target_el;
+    cpu_loop_exit(cs);
+}
+
+static int exception_target_el(CPUARMState *env)
+{
+    int target_el = MAX(1, arm_current_el(env));
+
+    /* No such thing as secure EL1 if EL3 is aarch32, so update the target EL
+     * to EL3 in this case.
+     */
+    if (arm_is_secure(env) && !arm_el_is_aa64(env, 3) && target_el == 1) {
+        target_el = 3;
+    }
+
+    return target_el;
+}
+
+uint32_t HELPER(neon_tbl)(CPUARMState *env, uint32_t ireg, uint32_t def,
+                          uint32_t rn, uint32_t maxindex)
+{
+    uint32_t val;
+    uint32_t tmp;
+    int index;
+    int shift;
+    uint64_t *table;
+    table = (uint64_t *)&env->vfp.regs[rn];
+    val = 0;
+    for (shift = 0; shift < 32; shift += 8) {
+        index = (ireg >> shift) & 0xff;
+        if (index < maxindex) {
+            tmp = (table[index >> 3] >> ((index & 7) << 3)) & 0xff;
+            val |= tmp << shift;
+        } else {
+            val |= def & (0xff << shift);
+        }
+    }
+    return val;
+}
+
+#if !defined(CONFIG_USER_ONLY)
+
+/* try to fill the TLB and return an exception if error. If retaddr is
+ * NULL, it means that the function was called in C code (i.e. not
+ * from generated code or from helper.c)
+ */
+void tlb_fill(CPUState *cs, target_ulong addr, int is_write, int mmu_idx,
+              uintptr_t retaddr)
+{
+    bool ret;
+    uint32_t fsr = 0;
+    ARMMMUFaultInfo fi = {};
+
+    ret = arm_tlb_fill(cs, addr, is_write, mmu_idx, &fsr, &fi);
+    if (unlikely(ret)) {
+        ARMCPU *cpu = ARM_CPU(cs);
+        CPUARMState *env = &cpu->env;
+        uint32_t syn, exc;
+        unsigned int target_el;
+        bool same_el;
+
+        if (retaddr) {
+            /* now we have a real cpu fault */
+            cpu_restore_state(cs, retaddr);
+        }
+
+        target_el = exception_target_el(env);
+        if (fi.stage2) {
+            target_el = 2;
+            env->cp15.hpfar_el2 = extract64(fi.s2addr, 12, 47) << 4;
+        }
+        same_el = arm_current_el(env) == target_el;
+        /* AArch64 syndrome does not have an LPAE bit */
+        syn = fsr & ~(1 << 9);
+
+        /* For insn and data aborts we assume there is no instruction syndrome
+         * information; this is always true for exceptions reported to EL1.
+         */
+        if (is_write == 2) {
+            syn = syn_insn_abort(same_el, 0, fi.s1ptw, syn);
+            exc = EXCP_PREFETCH_ABORT;
+        } else {
+            syn = syn_data_abort(same_el, 0, 0, fi.s1ptw, is_write == 1, syn);
+            if (is_write == 1 && arm_feature(env, ARM_FEATURE_V6)) {
+                fsr |= (1 << 11);
+            }
+            exc = EXCP_DATA_ABORT;
+        }
+
+        env->exception.vaddress = addr;
+        env->exception.fsr = fsr;
+        raise_exception(env, exc, syn, target_el);
+    }
+}
+#endif
+
+uint32_t HELPER(add_setq)(CPUARMState *env, uint32_t a, uint32_t b)
+{
+    uint32_t res = a + b;
+    if (((res ^ a) & SIGNBIT) && !((a ^ b) & SIGNBIT))
+        env->QF = 1;
+    return res;
+}
+
+uint32_t HELPER(add_saturate)(CPUARMState *env, uint32_t a, uint32_t b)
+{
+    uint32_t res = a + b;
+    if (((res ^ a) & SIGNBIT) && !((a ^ b) & SIGNBIT)) {
+        env->QF = 1;
+        res = ~(((int32_t)a >> 31) ^ SIGNBIT);
+    }
+    return res;
+}
+
+uint32_t HELPER(sub_saturate)(CPUARMState *env, uint32_t a, uint32_t b)
+{
+    uint32_t res = a - b;
+    if (((res ^ a) & SIGNBIT) && ((a ^ b) & SIGNBIT)) {
+        env->QF = 1;
+        res = ~(((int32_t)a >> 31) ^ SIGNBIT);
+    }
+    return res;
+}
+
+uint32_t HELPER(double_saturate)(CPUARMState *env, int32_t val)
+{
+    uint32_t res;
+    if (val >= 0x40000000) {
+        res = ~SIGNBIT;
+        env->QF = 1;
+    } else if (val <= (int32_t)0xc0000000) {
+        res = SIGNBIT;
+        env->QF = 1;
+    } else {
+        res = val << 1;
+    }
+    return res;
+}
+
+uint32_t HELPER(add_usaturate)(CPUARMState *env, uint32_t a, uint32_t b)
+{
+    uint32_t res = a + b;
+    if (res < a) {
+        env->QF = 1;
+        res = ~0;
+    }
+    return res;
+}
+
+uint32_t HELPER(sub_usaturate)(CPUARMState *env, uint32_t a, uint32_t b)
+{
+    uint32_t res = a - b;
+    if (res > a) {
+        env->QF = 1;
+        res = 0;
+    }
+    return res;
+}
+
+/* Signed saturation.  */
+static inline uint32_t do_ssat(CPUARMState *env, int32_t val, int shift)
+{
+    int32_t top;
+    uint32_t mask;
+
+    top = val >> shift;
+    mask = (1u << shift) - 1;
+    if (top > 0) {
+        env->QF = 1;
+        return mask;
+    } else if (top < -1) {
+        env->QF = 1;
+        return ~mask;
+    }
+    return val;
+}
+
+/* Unsigned saturation.  */
+static inline uint32_t do_usat(CPUARMState *env, int32_t val, int shift)
+{
+    uint32_t max;
+
+    max = (1u << shift) - 1;
+    if (val < 0) {
+        env->QF = 1;
+        return 0;
+    } else if (val > max) {
+        env->QF = 1;
+        return max;
+    }
+    return val;
+}
+
+/* Signed saturate.  */
+uint32_t HELPER(ssat)(CPUARMState *env, uint32_t x, uint32_t shift)
+{
+    return do_ssat(env, x, shift);
+}
+
+/* Dual halfword signed saturate.  */
+uint32_t HELPER(ssat16)(CPUARMState *env, uint32_t x, uint32_t shift)
+{
+    uint32_t res;
+
+    res = (uint16_t)do_ssat(env, (int16_t)x, shift);
+    res |= do_ssat(env, ((int32_t)x) >> 16, shift) << 16;
+    return res;
+}
+
+/* Unsigned saturate.  */
+uint32_t HELPER(usat)(CPUARMState *env, uint32_t x, uint32_t shift)
+{
+    return do_usat(env, x, shift);
+}
+
+/* Dual halfword unsigned saturate.  */
+uint32_t HELPER(usat16)(CPUARMState *env, uint32_t x, uint32_t shift)
+{
+    uint32_t res;
+
+    res = (uint16_t)do_usat(env, (int16_t)x, shift);
+    res |= do_usat(env, ((int32_t)x) >> 16, shift) << 16;
+    return res;
+}
+
+/* Function checks whether WFx (WFI/WFE) instructions are set up to be trapped.
+ * The function returns the target EL (1-3) if the instruction is to be trapped;
+ * otherwise it returns 0 indicating it is not trapped.
+ */
+static inline int check_wfx_trap(CPUARMState *env, bool is_wfe)
+{
+    int cur_el = arm_current_el(env);
+    uint64_t mask;
+
+    /* If we are currently in EL0 then we need to check if SCTLR is set up for
+     * WFx instructions being trapped to EL1. These trap bits don't exist in v7.
+     */
+    if (cur_el < 1 && arm_feature(env, ARM_FEATURE_V8)) {
+        int target_el;
+
+        mask = is_wfe ? SCTLR_nTWE : SCTLR_nTWI;
+        if (arm_is_secure_below_el3(env) && !arm_el_is_aa64(env, 3)) {
+            /* Secure EL0 and Secure PL1 is at EL3 */
+            target_el = 3;
+        } else {
+            target_el = 1;
+        }
+
+        if (!(env->cp15.sctlr_el[target_el] & mask)) {
+            return target_el;
+        }
+    }
+
+    /* We are not trapping to EL1; trap to EL2 if HCR_EL2 requires it
+     * No need for ARM_FEATURE check as if HCR_EL2 doesn't exist the
+     * bits will be zero indicating no trap.
+     */
+    if (cur_el < 2 && !arm_is_secure(env)) {
+        mask = (is_wfe) ? HCR_TWE : HCR_TWI;
+        if (env->cp15.hcr_el2 & mask) {
+            return 2;
+        }
+    }
+
+    /* We are not trapping to EL1 or EL2; trap to EL3 if SCR_EL3 requires it */
+    if (cur_el < 3) {
+        mask = (is_wfe) ? SCR_TWE : SCR_TWI;
+        if (env->cp15.scr_el3 & mask) {
+            return 3;
+        }
+    }
+
+    return 0;
+}
+
+void HELPER(wfi)(CPUARMState *env)
+{
+    CPUState *cs = CPU(arm_env_get_cpu(env));
+    int target_el = check_wfx_trap(env, false);
+
+    if (cpu_has_work(cs)) {
+        /* Don't bother to go into our "low power state" if
+         * we would just wake up immediately.
+         */
+        return;
+    }
+
+    if (target_el) {
+        env->pc -= 4;
+        raise_exception(env, EXCP_UDEF, syn_wfx(1, 0xe, 0), target_el);
+    }
+
+    cs->exception_index = EXCP_HLT;
+    cs->halted = 1;
+    cpu_loop_exit(cs);
+}
+
+void HELPER(wfe)(CPUARMState *env)
+{
+    /* This is a hint instruction that is semantically different
+     * from YIELD even though we currently implement it identically.
+     * Don't actually halt the CPU, just yield back to top
+     * level loop. This is not going into a "low power state"
+     * (ie halting until some event occurs), so we never take
+     * a configurable trap to a different exception level.
+     */
+    HELPER(yield)(env);
+}
+
+void HELPER(yield)(CPUARMState *env)
+{
+    ARMCPU *cpu = arm_env_get_cpu(env);
+    CPUState *cs = CPU(cpu);
+
+    /* This is a non-trappable hint instruction that generally indicates
+     * that the guest is currently busy-looping. Yield control back to the
+     * top level loop so that a more deserving VCPU has a chance to run.
+     */
+    cs->exception_index = EXCP_YIELD;
+    cpu_loop_exit(cs);
+}
+
+/* Raise an internal-to-QEMU exception. This is limited to only
+ * those EXCP values which are special cases for QEMU to interrupt
+ * execution and not to be used for exceptions which are passed to
+ * the guest (those must all have syndrome information and thus should
+ * use exception_with_syndrome).
+ */
+void HELPER(exception_internal)(CPUARMState *env, uint32_t excp)
+{
+    CPUState *cs = CPU(arm_env_get_cpu(env));
+
+    assert(excp_is_internal(excp));
+    cs->exception_index = excp;
+    cpu_loop_exit(cs);
+}
+
+/* Raise an exception with the specified syndrome register value */
+void HELPER(exception_with_syndrome)(CPUARMState *env, uint32_t excp,
+                                     uint32_t syndrome, uint32_t target_el)
+{
+    raise_exception(env, excp, syndrome, target_el);
+}
+
+uint32_t HELPER(cpsr_read)(CPUARMState *env)
+{
+    return cpsr_read(env) & ~(CPSR_EXEC | CPSR_RESERVED);
+}
+
+void HELPER(cpsr_write)(CPUARMState *env, uint32_t val, uint32_t mask)
+{
+    cpsr_write(env, val, mask);
+}
+
+void HELPER(cpsr_write_nzcv)(CPUARMState *env, uint32_t val, uint32_t mask)
+{
+    if (mask & CPSR_NZCV) {
+        env->ZF = (~val) & CPSR_Z;
+        env->NF = val;
+        env->CF = (val >> 29) & 1;
+        env->VF = (val << 3) & 0x80000000;
+    }
+}
+
+/* Access to user mode registers from privileged modes.  */
+uint32_t HELPER(get_user_reg)(CPUARMState *env, uint32_t regno)
+{
+    uint32_t val;
+
+    if (regno == 13) {
+        val = env->banked_r13[BANK_USRSYS];
+    } else if (regno == 14) {
+        val = env->banked_r14[BANK_USRSYS];
+    } else if (regno >= 8
+               && (env->uncached_cpsr & 0x1f) == ARM_CPU_MODE_FIQ) {
+        val = env->usr_regs[regno - 8];
+    } else {
+        val = env->regs[regno];
+    }
+    return val;
+}
+
+void HELPER(set_user_reg)(CPUARMState *env, uint32_t regno, uint32_t val)
+{
+    if (regno == 13) {
+        env->banked_r13[BANK_USRSYS] = val;
+    } else if (regno == 14) {
+        env->banked_r14[BANK_USRSYS] = val;
+    } else if (regno >= 8
+               && (env->uncached_cpsr & 0x1f) == ARM_CPU_MODE_FIQ) {
+        env->usr_regs[regno - 8] = val;
+    } else {
+        env->regs[regno] = val;
+    }
+}
+
+void HELPER(access_check_cp_reg)(CPUARMState *env, void *rip, uint32_t syndrome)
+{
+    const ARMCPRegInfo *ri = rip;
+    int target_el;
+
+    if (arm_feature(env, ARM_FEATURE_XSCALE) && ri->cp < 14
+        && extract32(env->cp15.c15_cpar, ri->cp, 1) == 0) {
+        raise_exception(env, EXCP_UDEF, syndrome, exception_target_el(env));
+    }
+
+    if (!ri->accessfn) {
+        return;
+    }
+
+    switch (ri->accessfn(env, ri)) {
+    case CP_ACCESS_OK:
+        return;
+    case CP_ACCESS_TRAP:
+        target_el = exception_target_el(env);
+        break;
+    case CP_ACCESS_TRAP_EL2:
+        /* Requesting a trap to EL2 when we're in EL3 or S-EL0/1 is
+         * a bug in the access function.
+         */
+        assert(!arm_is_secure(env) && arm_current_el(env) != 3);
+        target_el = 2;
+        break;
+    case CP_ACCESS_TRAP_EL3:
+        target_el = 3;
+        break;
+    case CP_ACCESS_TRAP_UNCATEGORIZED:
+        target_el = exception_target_el(env);
+        syndrome = syn_uncategorized();
+        break;
+    case CP_ACCESS_TRAP_UNCATEGORIZED_EL2:
+        target_el = 2;
+        syndrome = syn_uncategorized();
+        break;
+    case CP_ACCESS_TRAP_UNCATEGORIZED_EL3:
+        target_el = 3;
+        syndrome = syn_uncategorized();
+        break;
+    default:
+        g_assert_not_reached();
+    }
+
+    raise_exception(env, EXCP_UDEF, syndrome, target_el);
+}
+
+void HELPER(set_cp_reg)(CPUARMState *env, void *rip, uint32_t value)
+{
+    const ARMCPRegInfo *ri = rip;
+
+    ri->writefn(env, ri, value);
+}
+
+uint32_t HELPER(get_cp_reg)(CPUARMState *env, void *rip)
+{
+    const ARMCPRegInfo *ri = rip;
+
+    return ri->readfn(env, ri);
+}
+
+void HELPER(set_cp_reg64)(CPUARMState *env, void *rip, uint64_t value)
+{
+    const ARMCPRegInfo *ri = rip;
+
+    ri->writefn(env, ri, value);
+}
+
+uint64_t HELPER(get_cp_reg64)(CPUARMState *env, void *rip)
+{
+    const ARMCPRegInfo *ri = rip;
+
+    return ri->readfn(env, ri);
+}
+
+void HELPER(msr_i_pstate)(CPUARMState *env, uint32_t op, uint32_t imm)
+{
+    /* MSR_i to update PSTATE. This is OK from EL0 only if UMA is set.
+     * Note that SPSel is never OK from EL0; we rely on handle_msr_i()
+     * to catch that case at translate time.
+     */
+    if (arm_current_el(env) == 0 && !(env->cp15.sctlr_el[1] & SCTLR_UMA)) {
+        uint32_t syndrome = syn_aa64_sysregtrap(0, extract32(op, 0, 3),
+                                                extract32(op, 3, 3), 4,
+                                                imm, 0x1f, 0);
+        raise_exception(env, EXCP_UDEF, syndrome, exception_target_el(env));
+    }
+
+    switch (op) {
+    case 0x05: /* SPSel */
+        update_spsel(env, imm);
+        break;
+    case 0x1e: /* DAIFSet */
+        env->daif |= (imm << 6) & PSTATE_DAIF;
+        break;
+    case 0x1f: /* DAIFClear */
+        env->daif &= ~((imm << 6) & PSTATE_DAIF);
+        break;
+    default:
+        g_assert_not_reached();
+    }
+}
+
+void HELPER(clear_pstate_ss)(CPUARMState *env)
+{
+    env->pstate &= ~PSTATE_SS;
+}
+
+void HELPER(pre_hvc)(CPUARMState *env)
+{
+    ARMCPU *cpu = arm_env_get_cpu(env);
+    int cur_el = arm_current_el(env);
+    /* FIXME: Use actual secure state.  */
+    bool secure = false;
+    bool undef;
+
+    if (arm_is_psci_call(cpu, EXCP_HVC)) {
+        /* If PSCI is enabled and this looks like a valid PSCI call then
+         * that overrides the architecturally mandated HVC behaviour.
+         */
+        return;
+    }
+
+    if (!arm_feature(env, ARM_FEATURE_EL2)) {
+        /* If EL2 doesn't exist, HVC always UNDEFs */
+        undef = true;
+    } else if (arm_feature(env, ARM_FEATURE_EL3)) {
+        /* EL3.HCE has priority over EL2.HCD. */
+        undef = !(env->cp15.scr_el3 & SCR_HCE);
+    } else {
+        undef = env->cp15.hcr_el2 & HCR_HCD;
+    }
+
+    /* In ARMv7 and ARMv8/AArch32, HVC is undef in secure state.
+     * For ARMv8/AArch64, HVC is allowed in EL3.
+     * Note that we've already trapped HVC from EL0 at translation
+     * time.
+     */
+    if (secure && (!is_a64(env) || cur_el == 1)) {
+        undef = true;
+    }
+
+    if (undef) {
+        raise_exception(env, EXCP_UDEF, syn_uncategorized(),
+                        exception_target_el(env));
+    }
+}
+
+void HELPER(pre_smc)(CPUARMState *env, uint32_t syndrome)
+{
+    ARMCPU *cpu = arm_env_get_cpu(env);
+    int cur_el = arm_current_el(env);
+    bool secure = arm_is_secure(env);
+    bool smd = env->cp15.scr_el3 & SCR_SMD;
+    /* On ARMv8 AArch32, SMD only applies to NS state.
+     * On ARMv7 SMD only applies to NS state and only if EL2 is available.
+     * For ARMv7 non EL2, we force SMD to zero so we don't need to re-check
+     * the EL2 condition here.
+     */
+    bool undef = is_a64(env) ? smd : (!secure && smd);
+
+    if (arm_is_psci_call(cpu, EXCP_SMC)) {
+        /* If PSCI is enabled and this looks like a valid PSCI call then
+         * that overrides the architecturally mandated SMC behaviour.
+         */
+        return;
+    }
+
+    if (!arm_feature(env, ARM_FEATURE_EL3)) {
+        /* If we have no EL3 then SMC always UNDEFs */
+        undef = true;
+    } else if (!secure && cur_el == 1 && (env->cp15.hcr_el2 & HCR_TSC)) {
+        /* In NS EL1, HCR controlled routing to EL2 has priority over SMD. */
+        raise_exception(env, EXCP_HYP_TRAP, syndrome, 2);
+    }
+
+    if (undef) {
+        raise_exception(env, EXCP_UDEF, syn_uncategorized(),
+                        exception_target_el(env));
+    }
+}
+
+void HELPER(exception_return)(CPUARMState *env)
+{
+    int cur_el = arm_current_el(env);
+    unsigned int spsr_idx = aarch64_banked_spsr_index(cur_el);
+    uint32_t spsr = env->banked_spsr[spsr_idx];
+    int new_el;
+
+    aarch64_save_sp(env, cur_el);
+
+    env->exclusive_addr = -1;
+
+    /* We must squash the PSTATE.SS bit to zero unless both of the
+     * following hold:
+     *  1. debug exceptions are currently disabled
+     *  2. singlestep will be active in the EL we return to
+     * We check 1 here and 2 after we've done the pstate/cpsr write() to
+     * transition to the EL we're going to.
+     */
+    if (arm_generate_debug_exceptions(env)) {
+        spsr &= ~PSTATE_SS;
+    }
+
+    if (spsr & PSTATE_nRW) {
+        /* TODO: We currently assume EL1/2/3 are running in AArch64.  */
+        env->aarch64 = 0;
+        new_el = 0;
+        env->uncached_cpsr = 0x10;
+        cpsr_write(env, spsr, ~0);
+        if (!arm_singlestep_active(env)) {
+            env->uncached_cpsr &= ~PSTATE_SS;
+        }
+        aarch64_sync_64_to_32(env);
+
+        env->regs[15] = env->elr_el[1] & ~0x1;
+    } else {
+        new_el = extract32(spsr, 2, 2);
+        if (new_el > cur_el
+            || (new_el == 2 && !arm_feature(env, ARM_FEATURE_EL2))) {
+            /* Disallow return to an EL which is unimplemented or higher
+             * than the current one.
+             */
+            goto illegal_return;
+        }
+        if (extract32(spsr, 1, 1)) {
+            /* Return with reserved M[1] bit set */
+            goto illegal_return;
+        }
+        if (new_el == 0 && (spsr & PSTATE_SP)) {
+            /* Return to EL0 with M[0] bit set */
+            goto illegal_return;
+        }
+        env->aarch64 = 1;
+        pstate_write(env, spsr);
+        if (!arm_singlestep_active(env)) {
+            env->pstate &= ~PSTATE_SS;
+        }
+        aarch64_restore_sp(env, new_el);
+        env->pc = env->elr_el[cur_el];
+    }
+
+    return;
+
+illegal_return:
+    /* Illegal return events of various kinds have architecturally
+     * mandated behaviour:
+     * restore NZCV and DAIF from SPSR_ELx
+     * set PSTATE.IL
+     * restore PC from ELR_ELx
+     * no change to exception level, execution state or stack pointer
+     */
+    env->pstate |= PSTATE_IL;
+    env->pc = env->elr_el[cur_el];
+    spsr &= PSTATE_NZCV | PSTATE_DAIF;
+    spsr |= pstate_read(env) & ~(PSTATE_NZCV | PSTATE_DAIF);
+    pstate_write(env, spsr);
+    if (!arm_singlestep_active(env)) {
+        env->pstate &= ~PSTATE_SS;
+    }
+}
+
+/* Return true if the linked breakpoint entry lbn passes its checks */
+static bool linked_bp_matches(ARMCPU *cpu, int lbn)
+{
+    CPUARMState *env = &cpu->env;
+    uint64_t bcr = env->cp15.dbgbcr[lbn];
+    int brps = extract32(cpu->dbgdidr, 24, 4);
+    int ctx_cmps = extract32(cpu->dbgdidr, 20, 4);
+    int bt;
+    uint32_t contextidr;
+
+    /* Links to unimplemented or non-context aware breakpoints are
+     * CONSTRAINED UNPREDICTABLE: either behave as if disabled, or
+     * as if linked to an UNKNOWN context-aware breakpoint (in which
+     * case DBGWCR<n>_EL1.LBN must indicate that breakpoint).
+     * We choose the former.
+     */
+    if (lbn > brps || lbn < (brps - ctx_cmps)) {
+        return false;
+    }
+
+    bcr = env->cp15.dbgbcr[lbn];
+
+    if (extract64(bcr, 0, 1) == 0) {
+        /* Linked breakpoint disabled : generate no events */
+        return false;
+    }
+
+    bt = extract64(bcr, 20, 4);
+
+    /* We match the whole register even if this is AArch32 using the
+     * short descriptor format (in which case it holds both PROCID and ASID),
+     * since we don't implement the optional v7 context ID masking.
+     */
+    contextidr = extract64(env->cp15.contextidr_el[1], 0, 32);
+
+    switch (bt) {
+    case 3: /* linked context ID match */
+        if (arm_current_el(env) > 1) {
+            /* Context matches never fire in EL2 or (AArch64) EL3 */
+            return false;
+        }
+        return (contextidr == extract64(env->cp15.dbgbvr[lbn], 0, 32));
+    case 5: /* linked address mismatch (reserved in AArch64) */
+    case 9: /* linked VMID match (reserved if no EL2) */
+    case 11: /* linked context ID and VMID match (reserved if no EL2) */
+    default:
+        /* Links to Unlinked context breakpoints must generate no
+         * events; we choose to do the same for reserved values too.
+         */
+        return false;
+    }
+
+    return false;
+}
+
+static bool bp_wp_matches(ARMCPU *cpu, int n, bool is_wp)
+{
+    CPUARMState *env = &cpu->env;
+    uint64_t cr;
+    int pac, hmc, ssc, wt, lbn;
+    /* Note that for watchpoints the check is against the CPU security
+     * state, not the S/NS attribute on the offending data access.
+     */
+    bool is_secure = arm_is_secure(env);
+    int access_el = arm_current_el(env);
+
+    if (is_wp) {
+        CPUWatchpoint *wp = env->cpu_watchpoint[n];
+
+        if (!wp || !(wp->flags & BP_WATCHPOINT_HIT)) {
+            return false;
+        }
+        cr = env->cp15.dbgwcr[n];
+        if (wp->hitattrs.user) {
+            /* The LDRT/STRT/LDT/STT "unprivileged access" instructions should
+             * match watchpoints as if they were accesses done at EL0, even if
+             * the CPU is at EL1 or higher.
+             */
+            access_el = 0;
+        }
+    } else {
+        uint64_t pc = is_a64(env) ? env->pc : env->regs[15];
+
+        if (!env->cpu_breakpoint[n] || env->cpu_breakpoint[n]->pc != pc) {
+            return false;
+        }
+        cr = env->cp15.dbgbcr[n];
+    }
+    /* The WATCHPOINT_HIT flag guarantees us that the watchpoint is
+     * enabled and that the address and access type match; for breakpoints
+     * we know the address matched; check the remaining fields, including
+     * linked breakpoints. We rely on WCR and BCR having the same layout
+     * for the LBN, SSC, HMC, PAC/PMC and is-linked fields.
+     * Note that some combinations of {PAC, HMC, SSC} are reserved and
+     * must act either like some valid combination or as if the watchpoint
+     * were disabled. We choose the former, and use this together with
+     * the fact that EL3 must always be Secure and EL2 must always be
+     * Non-Secure to simplify the code slightly compared to the full
+     * table in the ARM ARM.
+     */
+    pac = extract64(cr, 1, 2);
+    hmc = extract64(cr, 13, 1);
+    ssc = extract64(cr, 14, 2);
+
+    switch (ssc) {
+    case 0:
+        break;
+    case 1:
+    case 3:
+        if (is_secure) {
+            return false;
+        }
+        break;
+    case 2:
+        if (!is_secure) {
+            return false;
+        }
+        break;
+    }
+
+    switch (access_el) {
+    case 3:
+    case 2:
+        if (!hmc) {
+            return false;
+        }
+        break;
+    case 1:
+        if (extract32(pac, 0, 1) == 0) {
+            return false;
+        }
+        break;
+    case 0:
+        if (extract32(pac, 1, 1) == 0) {
+            return false;
+        }
+        break;
+    default:
+        g_assert_not_reached();
+    }
+
+    wt = extract64(cr, 20, 1);
+    lbn = extract64(cr, 16, 4);
+
+    if (wt && !linked_bp_matches(cpu, lbn)) {
+        return false;
+    }
+
+    return true;
+}
+
+static bool check_watchpoints(ARMCPU *cpu)
+{
+    CPUARMState *env = &cpu->env;
+    int n;
+
+    /* If watchpoints are disabled globally or we can't take debug
+     * exceptions here then watchpoint firings are ignored.
+     */
+    if (extract32(env->cp15.mdscr_el1, 15, 1) == 0
+        || !arm_generate_debug_exceptions(env)) {
+        return false;
+    }
+
+    for (n = 0; n < ARRAY_SIZE(env->cpu_watchpoint); n++) {
+        if (bp_wp_matches(cpu, n, true)) {
+            return true;
+        }
+    }
+    return false;
+}
+
+static bool check_breakpoints(ARMCPU *cpu)
+{
+    CPUARMState *env = &cpu->env;
+    int n;
+
+    /* If breakpoints are disabled globally or we can't take debug
+     * exceptions here then breakpoint firings are ignored.
+     */
+    if (extract32(env->cp15.mdscr_el1, 15, 1) == 0
+        || !arm_generate_debug_exceptions(env)) {
+        return false;
+    }
+
+    for (n = 0; n < ARRAY_SIZE(env->cpu_breakpoint); n++) {
+        if (bp_wp_matches(cpu, n, false)) {
+            return true;
+        }
+    }
+    return false;
+}
+
+void HELPER(check_breakpoints)(CPUARMState *env)
+{
+    ARMCPU *cpu = arm_env_get_cpu(env);
+
+    if (check_breakpoints(cpu)) {
+        HELPER(exception_internal(env, EXCP_DEBUG));
+    }
+}
+
+void arm_debug_excp_handler(CPUState *cs)
+{
+    /* Called by core code when a watchpoint or breakpoint fires;
+     * need to check which one and raise the appropriate exception.
+     */
+    ARMCPU *cpu = ARM_CPU(cs);
+    CPUARMState *env = &cpu->env;
+    CPUWatchpoint *wp_hit = cs->watchpoint_hit;
+
+    if (wp_hit) {
+        if (wp_hit->flags & BP_CPU) {
+            cs->watchpoint_hit = NULL;
+            if (check_watchpoints(cpu)) {
+                bool wnr = (wp_hit->flags & BP_WATCHPOINT_HIT_WRITE) != 0;
+                bool same_el = arm_debug_target_el(env) == arm_current_el(env);
+
+                if (extended_addresses_enabled(env)) {
+                    env->exception.fsr = (1 << 9) | 0x22;
+                } else {
+                    env->exception.fsr = 0x2;
+                }
+                env->exception.vaddress = wp_hit->hitaddr;
+                raise_exception(env, EXCP_DATA_ABORT,
+                                syn_watchpoint(same_el, 0, wnr),
+                                arm_debug_target_el(env));
+            } else {
+                cpu_resume_from_signal(cs, NULL);
+            }
+        }
+    } else {
+        uint64_t pc = is_a64(env) ? env->pc : env->regs[15];
+        bool same_el = (arm_debug_target_el(env) == arm_current_el(env));
+
+        /* (1) GDB breakpoints should be handled first.
+         * (2) Do not raise a CPU exception if no CPU breakpoint has fired,
+         * since singlestep is also done by generating a debug internal
+         * exception.
+         */
+        if (cpu_breakpoint_test(cs, pc, BP_GDB)
+            || !cpu_breakpoint_test(cs, pc, BP_CPU)) {
+            return;
+        }
+
+        if (extended_addresses_enabled(env)) {
+            env->exception.fsr = (1 << 9) | 0x22;
+        } else {
+            env->exception.fsr = 0x2;
+        }
+        /* FAR is UNKNOWN, so doesn't need setting */
+        raise_exception(env, EXCP_PREFETCH_ABORT,
+                        syn_breakpoint(same_el),
+                        arm_debug_target_el(env));
+    }
+}
+
+/* ??? Flag setting arithmetic is awkward because we need to do comparisons.
+   The only way to do that in TCG is a conditional branch, which clobbers
+   all our temporaries.  For now implement these as helper functions.  */
+
+/* Similarly for variable shift instructions.  */
+
+uint32_t HELPER(shl_cc)(CPUARMState *env, uint32_t x, uint32_t i)
+{
+    int shift = i & 0xff;
+    if (shift >= 32) {
+        if (shift == 32)
+            env->CF = x & 1;
+        else
+            env->CF = 0;
+        return 0;
+    } else if (shift != 0) {
+        env->CF = (x >> (32 - shift)) & 1;
+        return x << shift;
+    }
+    return x;
+}
+
+uint32_t HELPER(shr_cc)(CPUARMState *env, uint32_t x, uint32_t i)
+{
+    int shift = i & 0xff;
+    if (shift >= 32) {
+        if (shift == 32)
+            env->CF = (x >> 31) & 1;
+        else
+            env->CF = 0;
+        return 0;
+    } else if (shift != 0) {
+        env->CF = (x >> (shift - 1)) & 1;
+        return x >> shift;
+    }
+    return x;
+}
+
+uint32_t HELPER(sar_cc)(CPUARMState *env, uint32_t x, uint32_t i)
+{
+    int shift = i & 0xff;
+    if (shift >= 32) {
+        env->CF = (x >> 31) & 1;
+        return (int32_t)x >> 31;
+    } else if (shift != 0) {
+        env->CF = (x >> (shift - 1)) & 1;
+        return (int32_t)x >> shift;
+    }
+    return x;
+}
+
+uint32_t HELPER(ror_cc)(CPUARMState *env, uint32_t x, uint32_t i)
+{
+    int shift1, shift;
+    shift1 = i & 0xff;
+    shift = shift1 & 0x1f;
+    if (shift == 0) {
+        if (shift1 != 0)
+            env->CF = (x >> 31) & 1;
+        return x;
+    } else {
+        env->CF = (x >> (shift - 1)) & 1;
+        return ((uint32_t)x >> shift) | (x << (32 - shift));
+    }
+}