powerpc: Extended ptrace interface

powerpc: Extended ptrace interface

From: Dave Kleikamp <shaggy@linux.vnet.ibm.com>

Based on patches originally written by Torez Smith.

Add a new extended ptrace interface so that user-space has a single
interface for powerpc, without having to know the specific layout
of the debug registers.

Implement:
PPC_PTRACE_GETHWDEBUGINFO
PPC_PTRACE_SETHWDEBUG
PPC_PTRACE_DELHWDEBUG

Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Acked-by: David Gibson <dwg@au1.ibm.com>
Cc: Torez Smith  <lnxtorez@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: Sergio Durigan Junior <sergiodj@br.ibm.com>
Cc: Thiago Jung Bauermann <bauerman@br.ibm.com>
Cc: linuxppc-dev list <Linuxppc-dev@ozlabs.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 90 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 292c81432014..8847bd618cec 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -835,6 +835,52 @@ void ptrace_disable(struct task_struct *child)
         user_disable_single_step(child);
 }
 
+static long ppc_set_hwdebug(struct task_struct *child,
+                     struct ppc_hw_breakpoint *bp_info)
+{
+        /*
+         * We currently support one data breakpoint
+         */
+        if (((bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_RW) == 0) ||
+            ((bp_info->trigger_type & ~PPC_BREAKPOINT_TRIGGER_RW) != 0) ||
+            (bp_info->trigger_type != PPC_BREAKPOINT_TRIGGER_WRITE) ||
+            (bp_info->addr_mode != PPC_BREAKPOINT_MODE_EXACT) ||
+            (bp_info->condition_mode != PPC_BREAKPOINT_CONDITION_NONE))
+                return -EINVAL;
+
+        if (child->thread.dabr)
+                return -ENOSPC;
+
+        if ((unsigned long)bp_info->addr >= TASK_SIZE)
+                return -EIO;
+
+        child->thread.dabr = (unsigned long)bp_info->addr;
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+        child->thread.dbcr0 = DBCR0_IDM;
+        if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_READ)
+                child->thread.dbcr0 |= DBSR_DAC1R;
+        if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_WRITE)
+                child->thread.dbcr0 |= DBSR_DAC1W;
+        child->thread.regs->msr |= MSR_DE;
+#endif
+        return 1;
+}
+
+static long ppc_del_hwdebug(struct task_struct *child, long addr, long data)
+{
+        if (data != 1)
+                return -EINVAL;
+        if (child->thread.dabr == 0)
+                return -ENOENT;
+
+        child->thread.dabr = 0;
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+        child->thread.dbcr0 &= ~(DBSR_DAC1R | DBSR_DAC1W | DBCR0_IDM);
+        child->thread.regs->msr &= ~MSR_DE;
+#endif
+        return 0;
+}
+
 /*
  * Here are the old "legacy" powerpc specific getregs/setregs ptrace calls,
  * we mark them as obsolete now, they will be removed in a future version
@@ -928,6 +974,50 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
                 break;
         }
 
+        case PPC_PTRACE_GETHWDBGINFO: {
+                struct ppc_debug_info dbginfo;
+
+                dbginfo.version = 1;
+                dbginfo.num_instruction_bps = 0;
+                dbginfo.num_data_bps = 1;
+                dbginfo.num_condition_regs = 0;
+#ifdef CONFIG_PPC64
+                dbginfo.data_bp_alignment = 8;
+#else
+                dbginfo.data_bp_alignment = 4;
+#endif
+                dbginfo.sizeof_condition = 0;
+                dbginfo.features = 0;
+
+                if (!access_ok(VERIFY_WRITE, data,
+                               sizeof(struct ppc_debug_info)))
+                        return -EFAULT;
+                ret = __copy_to_user((struct ppc_debug_info __user *)data,
+                                     &dbginfo, sizeof(struct ppc_debug_info)) ?
+                      -EFAULT : 0;
+                break;
+        }
+
+        case PPC_PTRACE_SETHWDEBUG: {
+                struct ppc_hw_breakpoint bp_info;
+
+                if (!access_ok(VERIFY_READ, data,
+                               sizeof(struct ppc_hw_breakpoint)))
+                        return -EFAULT;
+                ret = __copy_from_user(&bp_info,
+                                       (struct ppc_hw_breakpoint __user *)data,
+                                       sizeof(struct ppc_hw_breakpoint)) ?
+                      -EFAULT : 0;
+                if (!ret)
+                        ret = ppc_set_hwdebug(child, &bp_info);
+                break;
+        }
+
+        case PPC_PTRACE_DELHWDEBUG: {
+                ret = ppc_del_hwdebug(child, addr, data);
+                break;
+        }
+
         case PTRACE_GET_DEBUGREG: {
                 ret = -EINVAL;
                 /* We only support one DABR and no IABRS at the moment */