[PATCH] ppc64: Add PTRACE_{GET|SET}VRREGS

The ptrace get and set methods for VMX/Altivec registers present in the
ppc tree were missing for ppc64.  This patch adds the 32-bit and
64-bit methods.  Updated with the suggestions from Anton following the lines
of his code snippet.

Added:
 - flush_altivec_to_thread calls as suggested by Anton
 - piecewise copy of structure to preserve 32-bit vrsave data as per
   Anton

(I consolidated the 32 and 64bit versions with 2 helper macros - Anton)
Signed-off-by: Robert C Jennings <rcjenn@austin.ibm.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/ppc64/kernel/ptrace.c

@@ -17,6 +17,7 @@
  * this archive for more details.
  */
 
+#include <linux/config.h>
 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/mm.h>
@@ -274,6 +275,20 @@ int sys_ptrace(long request, long pid, long addr, long data)
 		break;
 	}
 
+#ifdef CONFIG_ALTIVEC
+	case PTRACE_GETVRREGS:
+		/* Get the child altivec register state. */
+		flush_altivec_to_thread(child);
+		ret = get_vrregs((unsigned long __user *)data, child);
+		break;
+
+	case PTRACE_SETVRREGS:
+		/* Set the child altivec register state. */
+		flush_altivec_to_thread(child);
+		ret = set_vrregs(child, (unsigned long __user *)data);
+		break;
+#endif
+
 	default:
 		ret = ptrace_request(child, request, addr, data);
 		break;

arch/ppc64/kernel/ptrace32.c

@@ -17,6 +17,7 @@
  * this archive for more details.
  */
 
+#include <linux/config.h>
 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/mm.h>
@@ -409,6 +410,20 @@ int sys32_ptrace(long request, long pid, unsigned long addr, unsigned long data)
                 ret = put_user(child->ptrace_message, (unsigned int __user *) data);
                 break;
 
+#ifdef CONFIG_ALTIVEC
+	case PTRACE_GETVRREGS:
+		/* Get the child altivec register state. */
+		flush_altivec_to_thread(child);
+		ret = get_vrregs((unsigned long __user *)data, child);
+		break;
+
+	case PTRACE_SETVRREGS:
+		/* Set the child altivec register state. */
+		flush_altivec_to_thread(child);
+		ret = set_vrregs(child, (unsigned long __user *)data);
+		break;
+#endif
+
 	default:
 		ret = ptrace_request(child, request, addr, data);
 		break;

include/asm-ppc64/ptrace-common.h

@@ -11,6 +11,9 @@
 
 #ifndef _PPC64_PTRACE_COMMON_H
 #define _PPC64_PTRACE_COMMON_H
+
+#include <linux/config.h>
+
 /*
  * Set of msr bits that gdb can change on behalf of a process.
  */
@@ -69,4 +72,73 @@ static inline void clear_single_step(struct task_struct *task)
 	clear_ti_thread_flag(task->thread_info, TIF_SINGLESTEP);
 }
 
+#ifdef CONFIG_ALTIVEC
+/*
+ * Get/set all the altivec registers vr0..vr31, vscr, vrsave, in one go.
+ * The transfer totals 34 quadword.  Quadwords 0-31 contain the
+ * corresponding vector registers.  Quadword 32 contains the vscr as the
+ * last word (offset 12) within that quadword.  Quadword 33 contains the
+ * vrsave as the first word (offset 0) within the quadword.
+ *
+ * This definition of the VMX state is compatible with the current PPC32
+ * ptrace interface.  This allows signal handling and ptrace to use the
+ * same structures.  This also simplifies the implementation of a bi-arch
+ * (combined (32- and 64-bit) gdb.
+ */
+
+/*
+ * Get contents of AltiVec register state in task TASK
+ */
+static inline int get_vrregs(unsigned long __user *data,
+			     struct task_struct *task)
+{
+	unsigned long regsize;
+
+	/* copy AltiVec registers VR[0] .. VR[31] */
+	regsize = 32 * sizeof(vector128);
+	if (copy_to_user(data, task->thread.vr, regsize))
+		return -EFAULT;
+	data += (regsize / sizeof(unsigned long));
+
+	/* copy VSCR */
+	regsize = 1 * sizeof(vector128);
+	if (copy_to_user(data, &task->thread.vscr, regsize))
+		return -EFAULT;
+	data += (regsize / sizeof(unsigned long));
+
+	/* copy VRSAVE */
+	if (put_user(task->thread.vrsave, (u32 __user *)data))
+		return -EFAULT;
+
+	return 0;
+}
+
+/*
+ * Write contents of AltiVec register state into task TASK.
+ */
+static inline int set_vrregs(struct task_struct *task,
+			     unsigned long __user *data)
+{
+	unsigned long regsize;
+
+	/* copy AltiVec registers VR[0] .. VR[31] */
+	regsize = 32 * sizeof(vector128);
+	if (copy_from_user(task->thread.vr, data, regsize))
+		return -EFAULT;
+	data += (regsize / sizeof(unsigned long));
+
+	/* copy VSCR */
+	regsize = 1 * sizeof(vector128);
+	if (copy_from_user(&task->thread.vscr, data, regsize))
+		return -EFAULT;
+	data += (regsize / sizeof(unsigned long));
+
+	/* copy VRSAVE */
+	if (get_user(task->thread.vrsave, (u32 __user *)data))
+		return -EFAULT;
+
+	return 0;
+}
+#endif
+
 #endif /* _PPC64_PTRACE_COMMON_H */