Patchwork [2/2] Add guest debug support

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Submitter Bharat Bhushan
Date July 26, 2012, 5:22 a.m.
Message ID <1343280157-3077-2-git-send-email-Bharat.Bhushan@freescale.com>
Download mbox | patch
Permalink /patch/173340/
State New
Headers show

Comments

Bharat Bhushan - July 26, 2012, 5:22 a.m.
This patch add support for guest debugging with qemu gdbstub.
Now hardware breakpoint and watchpoint can be set/unset. This
patch also support for software beakpoint.

Signed-off-by: Bharat Bhushan <bharat.bhushan@freescale.com>
---
 hw/ppc/e500.c        |    3 +
 target-ppc/kvm.c     |  242 ++++++++++++++++++++++++++++++++++++++++++++++++++
 target-ppc/kvm_ppc.h |    1 +
 3 files changed, 246 insertions(+), 0 deletions(-)

Patch

diff --git a/hw/ppc/e500.c b/hw/ppc/e500.c
index f07be08..83a2972 100644
--- a/hw/ppc/e500.c
+++ b/hw/ppc/e500.c
@@ -588,5 +588,8 @@  void ppce500_init(PPCE500Params *params)
 
     if (kvm_enabled()) {
         kvmppc_init();
+#ifdef KVM_CAP_SET_GUEST_DEBUG
+        kvmppc_e500_hw_breakpoint_init();
+#endif
     }
 }
diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index f70e7a6..f980700 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -33,6 +33,7 @@ 
 #include "hw/sysbus.h"
 #include "hw/spapr.h"
 #include "hw/watchdog.h"
+#include "gdbstub.h"
 
 #include "hw/sysbus.h"
 #include "hw/spapr.h"
@@ -805,6 +806,236 @@  static int kvmppc_handle_dcr_write(CPUPPCState *env, uint32_t dcrn, uint32_t dat
     return 0;
 }
 
+#ifdef KVM_CAP_SET_GUEST_DEBUG
+int kvm_arch_insert_sw_breakpoint(CPUPPCState *env,
+                                  struct kvm_sw_breakpoint *bp)
+{
+    uint32_t sc = tswap32(KVM_INST_GUESTGDB);
+
+    if (cpu_memory_rw_debug(env, bp->pc, (uint8_t *)&bp->saved_insn, 4, 0) ||
+        cpu_memory_rw_debug(env, bp->pc, (uint8_t *)&sc, 4, 1)) {
+        return -EINVAL;
+    }
+
+    return 0;
+}
+
+int kvm_arch_remove_sw_breakpoint(CPUPPCState *env,
+                                  struct kvm_sw_breakpoint *bp)
+{
+    uint32_t sc;
+
+    if (cpu_memory_rw_debug(env, bp->pc, (uint8_t *)&sc, 4, 0) ||
+        sc != tswap32(KVM_INST_GUESTGDB) ||
+        cpu_memory_rw_debug(env, bp->pc, (uint8_t *)&bp->saved_insn, 4, 1)) {
+        return -EINVAL;
+    }
+
+    return 0;
+}
+
+static struct HWBreakpoint {
+    target_ulong addr;
+    int type;
+} hw_breakpoint[6];
+
+static int nb_hw_breakpoint;
+static int nb_hw_watchpoint;
+static int max_hw_breakpoint = 4;
+static int max_hw_watchpoint = 2;
+
+void kvmppc_e500_hw_breakpoint_init(void)
+{
+    max_hw_breakpoint = 2;
+    max_hw_watchpoint = 2;
+}
+
+static int find_hw_breakpoint(target_ulong addr, int type)
+{
+    int n;
+
+    for (n = 0; n < nb_hw_breakpoint + nb_hw_watchpoint; n++) {
+        if (hw_breakpoint[n].addr == addr && hw_breakpoint[n].type == type) {
+            return n;
+        }
+    }
+
+    return -1;
+}
+
+static int find_hw_watchpoint(target_ulong addr, int *flag)
+{
+    int n;
+
+    n = find_hw_breakpoint(addr, GDB_WATCHPOINT_ACCESS);
+    if (n >= 0) {
+        *flag = BP_MEM_ACCESS;
+        return n;
+    }
+
+    n = find_hw_breakpoint(addr, KVMPPC_DEBUG_WATCH_WRITE);
+    if (n >= 0) {
+        *flag = BP_MEM_WRITE;
+        return n;
+    }
+
+    n = find_hw_breakpoint(addr, KVMPPC_DEBUG_WATCH_READ);
+    if (n >= 0) {
+        *flag = BP_MEM_READ;
+        return n;
+    }
+
+    return -1;
+}
+
+int kvm_arch_insert_hw_breakpoint(target_ulong addr,
+                                  target_ulong len, int type)
+{
+    hw_breakpoint[nb_hw_breakpoint + nb_hw_watchpoint].addr = addr;
+    hw_breakpoint[nb_hw_breakpoint + nb_hw_watchpoint].type = type;
+
+    switch (type) {
+    case GDB_BREAKPOINT_HW:
+        if (nb_hw_breakpoint >= max_hw_breakpoint) {
+            return -ENOBUFS;
+        }
+
+        if (find_hw_breakpoint(addr, type) >= 0) {
+            return -EEXIST;
+        }
+
+        nb_hw_breakpoint++;
+        break;
+
+    case GDB_WATCHPOINT_WRITE:
+    case GDB_WATCHPOINT_READ:
+    case GDB_WATCHPOINT_ACCESS:
+        if (nb_hw_watchpoint >= max_hw_watchpoint) {
+            return -ENOBUFS;
+        }
+
+        if (find_hw_breakpoint(addr, type) >= 0) {
+            return -EEXIST;
+        }
+
+        nb_hw_watchpoint++;
+        break;
+
+    default:
+        return -ENOSYS;
+    }
+
+    return 0;
+}
+
+int kvm_arch_remove_hw_breakpoint(target_ulong addr,
+                                  target_ulong len, int type)
+{
+    int n;
+
+    n = find_hw_breakpoint(addr, type);
+    if (n < 0) {
+        return -ENOENT;
+    }
+
+    switch (type) {
+    case GDB_BREAKPOINT_HW:
+        nb_hw_breakpoint--;
+        break;
+
+    case GDB_WATCHPOINT_WRITE:
+    case GDB_WATCHPOINT_READ:
+    case GDB_WATCHPOINT_ACCESS:
+        nb_hw_watchpoint--;
+        break;
+
+    default:
+        return -ENOSYS;
+    }
+    hw_breakpoint[n] = hw_breakpoint[nb_hw_breakpoint + nb_hw_watchpoint];
+
+    return 0;
+}
+
+void kvm_arch_remove_all_hw_breakpoints(void)
+{
+    nb_hw_breakpoint = nb_hw_watchpoint = 0;
+}
+
+static CPUWatchpoint hw_watchpoint;
+
+
+static int kvm_handle_debug(struct kvm_debug_exit_arch *arch_info)
+{
+    int handle = 0;
+    int n;
+    int flag = 0;
+
+    if (cpu_single_env->singlestep_enabled) {
+        handle = 1;
+    } else if (arch_info->status) {
+        if (arch_info->status & KVMPPC_DEBUG_BREAKPOINT) {
+            n = find_hw_breakpoint(arch_info->pc, GDB_BREAKPOINT_HW);
+            if (n >= 0) {
+                handle = 1;
+            }
+        } else if (arch_info->status & (KVMPPC_DEBUG_WATCH_READ |
+                                        KVMPPC_DEBUG_WATCH_WRITE)) {
+            n = find_hw_watchpoint(arch_info->pc,  &flag);
+            if (n >= 0) {
+                handle = 1;
+                cpu_single_env->watchpoint_hit = &hw_watchpoint;
+                hw_watchpoint.vaddr = hw_breakpoint[n].addr;
+                hw_watchpoint.flags = flag;
+            }
+        }
+    } else if (kvm_find_sw_breakpoint(cpu_single_env, arch_info->pc)) {
+        handle = 1;
+    }
+
+    /* XXX inject guest debug exception */
+    if (!handle) {
+        fprintf(stderr, "Unhandled debug exception!\n");
+    }
+
+    return handle;
+}
+
+void kvm_arch_update_guest_debug(CPUPPCState *env, struct kvm_guest_debug *dbg)
+{
+    if (kvm_sw_breakpoints_active(env)) {
+        dbg->control |= KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP;
+    }
+
+    if (nb_hw_breakpoint + nb_hw_watchpoint > 0) {
+        int n;
+
+        dbg->control |= KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_HW_BP;
+        memset(dbg->arch.bp, 0, sizeof(dbg->arch.bp));
+        for (n = 0; n < nb_hw_breakpoint + nb_hw_watchpoint; n++) {
+            switch (hw_breakpoint[n].type) {
+            case GDB_BREAKPOINT_HW:
+                dbg->arch.bp[n].type = KVMPPC_DEBUG_BREAKPOINT;
+                break;
+            case GDB_WATCHPOINT_WRITE:
+                dbg->arch.bp[n].type = KVMPPC_DEBUG_WATCH_WRITE;
+                break;
+            case GDB_WATCHPOINT_READ:
+                dbg->arch.bp[n].type = KVMPPC_DEBUG_WATCH_READ;
+                break;
+            case GDB_WATCHPOINT_ACCESS:
+                dbg->arch.bp[n].type = KVMPPC_DEBUG_WATCH_WRITE |
+                                        KVMPPC_DEBUG_WATCH_READ;
+                break;
+            default:
+                cpu_abort(env, "Unsupported breakpoint type\n");
+            }
+            dbg->arch.bp[n].addr = hw_breakpoint[n].addr;
+        }
+    }
+}
+#endif /* KVM_CAP_SET_GUEST_DEBUG */
+
 int kvm_arch_handle_exit(CPUPPCState *env, struct kvm_run *run)
 {
     int ret;
@@ -838,6 +1069,17 @@  int kvm_arch_handle_exit(CPUPPCState *env, struct kvm_run *run)
         ret = 0;
         break;
 #endif
+#ifdef KVM_CAP_SET_GUEST_DEBUG
+    case KVM_EXIT_DEBUG:
+        dprintf("kvm_exit_debug\n");
+        if (kvm_handle_debug(&run->debug.arch)) {
+            ret = EXCP_DEBUG;
+            break;
+        }
+        /* re-enter, this exception was guest-internal */
+        ret = 0;
+        break;
+#endif
     default:
         fprintf(stderr, "KVM: unknown exit reason %d\n", run->exit_reason);
         ret = -1;
diff --git a/target-ppc/kvm_ppc.h b/target-ppc/kvm_ppc.h
index e2f8703..6e34cf3 100644
--- a/target-ppc/kvm_ppc.h
+++ b/target-ppc/kvm_ppc.h
@@ -30,6 +30,7 @@  int kvmppc_remove_spapr_tce(void *table, int pfd, uint32_t window_size);
 #endif /* !CONFIG_USER_ONLY */
 const ppc_def_t *kvmppc_host_cpu_def(void);
 int kvmppc_fixup_cpu(CPUPPCState *env);
+void kvmppc_e500_hw_breakpoint_init(void);
 
 #else