powerpc: Extended ptrace interface

From: Torez Smith <lnxto...@linux.vnet.ibm.com>

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 <sha...@linux.vnet.ibm.com>
Signed-off-by: Torez Smith  <lnxto...@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org>
Cc: Thiago Jung Bauermann <bauer...@br.ibm.com>
Cc: Sergio Durigan Junior <sergi...@br.ibm.com>
Cc: David Gibson <d...@au1.ibm.com>
Cc: linuxppc-dev list <linuxppc-...@ozlabs.org>
---

 arch/powerpc/include/asm/ptrace.h |   75 ++++++++++++++++++++++++++++++++
 arch/powerpc/kernel/ptrace.c      |   88 +++++++++++++++++++++++++++++++++++++
 2 files changed, 163 insertions(+), 0 deletions(-)


diff --git a/arch/powerpc/include/asm/ptrace.h 
b/arch/powerpc/include/asm/ptrace.h
index 8c34149..7ae887b 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -24,6 +24,12 @@
  * 2 of the License, or (at your option) any later version.
  */
 
+#ifdef __KERNEL__
+#include <linux/types.h>
+#else
+#include <stdint.h>
+#endif
+
 #ifndef __ASSEMBLY__
 
 struct pt_regs {
@@ -292,4 +298,73 @@ extern void user_disable_single_step(struct task_struct *);
 
 #define PTRACE_SINGLEBLOCK     0x100   /* resume execution until next branch */
 
+#define PPC_PTRACE_GETHWDBGINFO        0x89
+#define PPC_PTRACE_SETHWDEBUG  0x88
+#define PPC_PTRACE_DELHWDEBUG  0x87
+
+#ifndef __ASSEMBLY__
+
+struct ppc_debug_info {
+       uint32_t version;               /* Only version 1 exists to date */
+       uint32_t num_instruction_bps;
+       uint32_t num_data_bps;
+       uint32_t num_condition_regs;
+       uint32_t data_bp_alignment;
+       uint32_t sizeof_condition;      /* size of the DVC register */
+       uint64_t features;
+};
+
+#endif /* __ASSEMBLY__ */
+
+/*
+ * features will have bits indication whether there is support for:
+ */
+#define PPC_DEBUG_FEATURE_INSN_BP_RANGE                0x1
+#define PPC_DEBUG_FEATURE_INSN_BP_MASK         0x2
+#define PPC_DEBUG_FEATURE_DATA_BP_RANGE                0x4
+#define PPC_DEBUG_FEATURE_DATA_BP_MASK         0x8
+
+#ifndef __ASSEMBLY__
+
+struct ppc_hw_breakpoint {
+       uint32_t version;               /* currently, version must be 1 */
+       uint32_t trigger_type;          /* only some combinations allowed */
+       uint32_t addr_mode;             /* address match mode */
+       uint32_t condition_mode;        /* break/watchpoint condition flags */
+       uint64_t addr;                  /* break/watchpoint address */
+       uint64_t addr2;                 /* range end or mask */
+       uint64_t condition_value;       /* contents of the DVC register */
+};
+
+#endif /* __ASSEMBLY__ */
+
+/*
+ * Trigger Type
+ */
+#define PPC_BREAKPOINT_TRIGGER_EXECUTE 0x1
+#define PPC_BREAKPOINT_TRIGGER_READ    0x2
+#define PPC_BREAKPOINT_TRIGGER_WRITE   0x4
+#define PPC_BREAKPOINT_TRIGGER_RW      0x6
+
+/*
+ * Address Mode
+ */
+#define PPC_BREAKPOINT_MODE_EXACT              0x0
+#define PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE    0x1
+#define PPC_BREAKPOINT_MODE_RANGE_EXCLUSIVE    0x2
+#define PPC_BREAKPOINT_MODE_MASK               0x3
+
+/*
+ * Condition Mode
+ */
+#define PPC_BREAKPOINT_CONDITION_NONE  0x0
+#define PPC_BREAKPOINT_CONDITION_AND   0x1
+#define PPC_BREAKPOINT_CONDITION_EXACT 0x1
+#define PPC_BREAKPOINT_CONDITION_OR    0x2
+#define PPC_BREAKPOINT_CONDITION_AND_OR        0x3
+#define PPC_BREAKPOINT_CONDITION_BE_ALL        0x00ff0000
+#define PPC_BREAKPOINT_CONDITION_BE_SHIFT      16
+#define PPC_BREAKPOINT_CONDITION_BE(n) \
+       (1<<((n)+PPC_BREAKPOINT_CONDITION_BE_SHIFT))
+
 #endif /* _ASM_POWERPC_PTRACE_H */
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index ef14988..6be2ce0 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -839,6 +839,50 @@ 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_BOOKE
+       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) || (child->thread.dabr == 0))
+               return -EINVAL;
+
+       child->thread.dabr = 0;
+#ifdef CONFIG_BOOKE
+       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
@@ -932,6 +976,50 @@ 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 = 0;
+#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 */

-- 
Dave Kleikamp
IBM Linux Technology Center
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