hvf: add breakpoint handlers

Required for guest debugging. The code has been structured like the KVM
counterpart.

Signed-off-by: Francesco Cagnin <fcagnin@quarkslab.com>
Message-id: 20230601153107.81955-4-fcagnin@quarkslab.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

accel/hvf/hvf-accel-ops.c

@@ -52,6 +52,7 @@
 #include "qemu/main-loop.h"
 #include "exec/address-spaces.h"
 #include "exec/exec-all.h"
+#include "exec/gdbstub.h"
 #include "sysemu/cpus.h"
 #include "sysemu/hvf.h"
 #include "sysemu/hvf_int.h"
@@ -334,6 +335,8 @@ static int hvf_accel_init(MachineState *ms)
         s->slots[x].slot_id = x;
     }
 
+    QTAILQ_INIT(&s->hvf_sw_breakpoints);
+
     hvf_state = s;
     memory_listener_register(&hvf_memory_listener, &address_space_memory);
 
@@ -462,6 +465,108 @@ static void hvf_start_vcpu_thread(CPUState *cpu)
                        cpu, QEMU_THREAD_JOINABLE);
 }
 
+static int hvf_insert_breakpoint(CPUState *cpu, int type, hwaddr addr, hwaddr len)
+{
+    struct hvf_sw_breakpoint *bp;
+    int err;
+
+    if (type == GDB_BREAKPOINT_SW) {
+        bp = hvf_find_sw_breakpoint(cpu, addr);
+        if (bp) {
+            bp->use_count++;
+            return 0;
+        }
+
+        bp = g_new(struct hvf_sw_breakpoint, 1);
+        bp->pc = addr;
+        bp->use_count = 1;
+        err = hvf_arch_insert_sw_breakpoint(cpu, bp);
+        if (err) {
+            g_free(bp);
+            return err;
+        }
+
+        QTAILQ_INSERT_HEAD(&hvf_state->hvf_sw_breakpoints, bp, entry);
+    } else {
+        err = hvf_arch_insert_hw_breakpoint(addr, len, type);
+        if (err) {
+            return err;
+        }
+    }
+
+    CPU_FOREACH(cpu) {
+        err = hvf_update_guest_debug(cpu);
+        if (err) {
+            return err;
+        }
+    }
+    return 0;
+}
+
+static int hvf_remove_breakpoint(CPUState *cpu, int type, hwaddr addr, hwaddr len)
+{
+    struct hvf_sw_breakpoint *bp;
+    int err;
+
+    if (type == GDB_BREAKPOINT_SW) {
+        bp = hvf_find_sw_breakpoint(cpu, addr);
+        if (!bp) {
+            return -ENOENT;
+        }
+
+        if (bp->use_count > 1) {
+            bp->use_count--;
+            return 0;
+        }
+
+        err = hvf_arch_remove_sw_breakpoint(cpu, bp);
+        if (err) {
+            return err;
+        }
+
+        QTAILQ_REMOVE(&hvf_state->hvf_sw_breakpoints, bp, entry);
+        g_free(bp);
+    } else {
+        err = hvf_arch_remove_hw_breakpoint(addr, len, type);
+        if (err) {
+            return err;
+        }
+    }
+
+    CPU_FOREACH(cpu) {
+        err = hvf_update_guest_debug(cpu);
+        if (err) {
+            return err;
+        }
+    }
+    return 0;
+}
+
+static void hvf_remove_all_breakpoints(CPUState *cpu)
+{
+    struct hvf_sw_breakpoint *bp, *next;
+    CPUState *tmpcpu;
+
+    QTAILQ_FOREACH_SAFE(bp, &hvf_state->hvf_sw_breakpoints, entry, next) {
+        if (hvf_arch_remove_sw_breakpoint(cpu, bp) != 0) {
+            /* Try harder to find a CPU that currently sees the breakpoint. */
+            CPU_FOREACH(tmpcpu)
+            {
+                if (hvf_arch_remove_sw_breakpoint(tmpcpu, bp) == 0) {
+                    break;
+                }
+            }
+        }
+        QTAILQ_REMOVE(&hvf_state->hvf_sw_breakpoints, bp, entry);
+        g_free(bp);
+    }
+    hvf_arch_remove_all_hw_breakpoints();
+
+    CPU_FOREACH(cpu) {
+        hvf_update_guest_debug(cpu);
+    }
+}
+
 static void hvf_accel_ops_class_init(ObjectClass *oc, void *data)
 {
     AccelOpsClass *ops = ACCEL_OPS_CLASS(oc);
@@ -473,6 +578,10 @@ static void hvf_accel_ops_class_init(ObjectClass *oc, void *data)
     ops->synchronize_post_init = hvf_cpu_synchronize_post_init;
     ops->synchronize_state = hvf_cpu_synchronize_state;
     ops->synchronize_pre_loadvm = hvf_cpu_synchronize_pre_loadvm;
+
+    ops->insert_breakpoint = hvf_insert_breakpoint;
+    ops->remove_breakpoint = hvf_remove_breakpoint;
+    ops->remove_all_breakpoints = hvf_remove_all_breakpoints;
 };
 static const TypeInfo hvf_accel_ops_type = {
     .name = ACCEL_OPS_NAME("hvf"),

accel/hvf/hvf-all.c

@@ -44,3 +44,20 @@ void assert_hvf_ok(hv_return_t ret)
 
     abort();
 }
+
+struct hvf_sw_breakpoint *hvf_find_sw_breakpoint(CPUState *cpu, target_ulong pc)
+{
+    struct hvf_sw_breakpoint *bp;
+
+    QTAILQ_FOREACH(bp, &hvf_state->hvf_sw_breakpoints, entry) {
+        if (bp->pc == pc) {
+            return bp;
+        }
+    }
+    return NULL;
+}
+
+int hvf_sw_breakpoints_active(CPUState *cpu)
+{
+    return !QTAILQ_EMPTY(&hvf_state->hvf_sw_breakpoints);
+}

include/sysemu/hvf.h

@@ -17,6 +17,7 @@
 #include "qom/object.h"
 
 #ifdef NEED_CPU_H
+#include "cpu.h"
 
 #ifdef CONFIG_HVF
 uint32_t hvf_get_supported_cpuid(uint32_t func, uint32_t idx,
@@ -36,4 +37,25 @@ typedef struct HVFState HVFState;
 DECLARE_INSTANCE_CHECKER(HVFState, HVF_STATE,
                          TYPE_HVF_ACCEL)
 
+#ifdef NEED_CPU_H
+struct hvf_sw_breakpoint {
+    target_ulong pc;
+    target_ulong saved_insn;
+    int use_count;
+    QTAILQ_ENTRY(hvf_sw_breakpoint) entry;
+};
+
+struct hvf_sw_breakpoint *hvf_find_sw_breakpoint(CPUState *cpu,
+                                                 target_ulong pc);
+int hvf_sw_breakpoints_active(CPUState *cpu);
+
+int hvf_arch_insert_sw_breakpoint(CPUState *cpu, struct hvf_sw_breakpoint *bp);
+int hvf_arch_remove_sw_breakpoint(CPUState *cpu, struct hvf_sw_breakpoint *bp);
+int hvf_arch_insert_hw_breakpoint(target_ulong addr, target_ulong len,
+                                  int type);
+int hvf_arch_remove_hw_breakpoint(target_ulong addr, target_ulong len,
+                                  int type);
+void hvf_arch_remove_all_hw_breakpoints(void);
+#endif /* NEED_CPU_H */
+
 #endif

include/sysemu/hvf_int.h

@@ -45,6 +45,7 @@ struct HVFState {
 
     hvf_vcpu_caps *hvf_caps;
     uint64_t vtimer_offset;
+    QTAILQ_HEAD(, hvf_sw_breakpoint) hvf_sw_breakpoints;
 };
 extern HVFState *hvf_state;
 

target/arm/hvf/hvf.c

@@ -31,6 +31,8 @@
 #include "trace/trace-target_arm_hvf.h"
 #include "migration/vmstate.h"
 
+#include "exec/gdbstub.h"
+
 #define HVF_SYSREG(crn, crm, op0, op1, op2) \
         ENCODE_AA64_CP_REG(CP_REG_ARM64_SYSREG_CP, crn, crm, op0, op1, op2)
 #define PL1_WRITE_MASK 0x4
@@ -1711,3 +1713,64 @@ int hvf_arch_init(void)
     qemu_add_vm_change_state_handler(hvf_vm_state_change, &vtimer);
     return 0;
 }
+
+static const uint32_t brk_insn = 0xd4200000;
+
+int hvf_arch_insert_sw_breakpoint(CPUState *cpu, struct hvf_sw_breakpoint *bp)
+{
+    if (cpu_memory_rw_debug(cpu, bp->pc, (uint8_t *)&bp->saved_insn, 4, 0) ||
+        cpu_memory_rw_debug(cpu, bp->pc, (uint8_t *)&brk_insn, 4, 1)) {
+        return -EINVAL;
+    }
+    return 0;
+}
+
+int hvf_arch_remove_sw_breakpoint(CPUState *cpu, struct hvf_sw_breakpoint *bp)
+{
+    static uint32_t brk;
+
+    if (cpu_memory_rw_debug(cpu, bp->pc, (uint8_t *)&brk, 4, 0) ||
+        brk != brk_insn ||
+        cpu_memory_rw_debug(cpu, bp->pc, (uint8_t *)&bp->saved_insn, 4, 1)) {
+        return -EINVAL;
+    }
+    return 0;
+}
+
+int hvf_arch_insert_hw_breakpoint(target_ulong addr, target_ulong len, int type)
+{
+    switch (type) {
+    case GDB_BREAKPOINT_HW:
+        return insert_hw_breakpoint(addr);
+    case GDB_WATCHPOINT_READ:
+    case GDB_WATCHPOINT_WRITE:
+    case GDB_WATCHPOINT_ACCESS:
+        return insert_hw_watchpoint(addr, len, type);
+    default:
+        return -ENOSYS;
+    }
+}
+
+int hvf_arch_remove_hw_breakpoint(target_ulong addr, target_ulong len, int type)
+{
+    switch (type) {
+    case GDB_BREAKPOINT_HW:
+        return delete_hw_breakpoint(addr);
+    case GDB_WATCHPOINT_READ:
+    case GDB_WATCHPOINT_WRITE:
+    case GDB_WATCHPOINT_ACCESS:
+        return delete_hw_watchpoint(addr, len, type);
+    default:
+        return -ENOSYS;
+    }
+}
+
+void hvf_arch_remove_all_hw_breakpoints(void)
+{
+    if (cur_hw_wps > 0) {
+        g_array_remove_range(hw_watchpoints, 0, cur_hw_wps);
+    }
+    if (cur_hw_bps > 0) {
+        g_array_remove_range(hw_breakpoints, 0, cur_hw_bps);
+    }
+}

target/i386/hvf/hvf.c

@@ -679,3 +679,27 @@ int hvf_vcpu_exec(CPUState *cpu)
 
     return ret;
 }
+
+int hvf_arch_insert_sw_breakpoint(CPUState *cpu, struct hvf_sw_breakpoint *bp)
+{
+    return -ENOSYS;
+}
+
+int hvf_arch_remove_sw_breakpoint(CPUState *cpu, struct hvf_sw_breakpoint *bp)
+{
+    return -ENOSYS;
+}
+
+int hvf_arch_insert_hw_breakpoint(target_ulong addr, target_ulong len, int type)
+{
+    return -ENOSYS;
+}
+
+int hvf_arch_remove_hw_breakpoint(target_ulong addr, target_ulong len, int type)
+{
+    return -ENOSYS;
+}
+
+void hvf_arch_remove_all_hw_breakpoints(void)
+{
+}