target/arm: Move debug routines to debug_helper.c

These routines are TCG specific.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20190701194942.10092-2-philmd@redhat.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 311 insertions, 0 deletions

diff --git a/target/arm/debug_helper.c b/target/arm/debug_helper.c
new file mode 100644
index 0000000000..dde80273ff
--- /dev/null
+++ b/target/arm/debug_helper.c
@@ -0,0 +1,311 @@
+/*
+ * ARM debug helpers.
+ *
+ * This code is licensed under the GNU GPL v2 or later.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#include "qemu/osdep.h"
+#include "cpu.h"
+#include "internals.h"
+#include "exec/exec-all.h"
+#include "exec/helper-proto.h"
+
+/* 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 = env_archcpu(env);
+
+    if (check_breakpoints(cpu)) {
+        HELPER(exception_internal(env, EXCP_DEBUG));
+    }
+}
+
+bool arm_debug_check_watchpoint(CPUState *cs, CPUWatchpoint *wp)
+{
+    /*
+     * Called by core code when a CPU watchpoint fires; need to check if this
+     * is also an architectural watchpoint match.
+     */
+    ARMCPU *cpu = ARM_CPU(cs);
+
+    return check_watchpoints(cpu);
+}
+
+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) {
+            bool wnr = (wp_hit->flags & BP_WATCHPOINT_HIT_WRITE) != 0;
+            bool same_el = arm_debug_target_el(env) == arm_current_el(env);
+
+            cs->watchpoint_hit = NULL;
+
+            env->exception.fsr = arm_debug_exception_fsr(env);
+            env->exception.vaddress = wp_hit->hitaddr;
+            raise_exception(env, EXCP_DATA_ABORT,
+                    syn_watchpoint(same_el, 0, wnr),
+                    arm_debug_target_el(env));
+        }
+    } 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;
+        }
+
+        env->exception.fsr = arm_debug_exception_fsr(env);
+        /*
+         * FAR is UNKNOWN: clear vaddress to avoid potentially exposing
+         * values to the guest that it shouldn't be able to see at its
+         * exception/security level.
+         */
+        env->exception.vaddress = 0;
+        raise_exception(env, EXCP_PREFETCH_ABORT,
+                        syn_breakpoint(same_el),
+                        arm_debug_target_el(env));
+    }
+}
+
+#if !defined(CONFIG_USER_ONLY)
+
+vaddr arm_adjust_watchpoint_address(CPUState *cs, vaddr addr, int len)
+{
+    ARMCPU *cpu = ARM_CPU(cs);
+    CPUARMState *env = &cpu->env;
+
+    /*
+     * In BE32 system mode, target memory is stored byteswapped (on a
+     * little-endian host system), and by the time we reach here (via an
+     * opcode helper) the addresses of subword accesses have been adjusted
+     * to account for that, which means that watchpoints will not match.
+     * Undo the adjustment here.
+     */
+    if (arm_sctlr_b(env)) {
+        if (len == 1) {
+            addr ^= 3;
+        } else if (len == 2) {
+            addr ^= 2;
+        }
+    }
+
+    return addr;
+}
+
+#endif