1 files changed, 66 insertions, 6 deletions

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 8feb93e7890c..a5d0e78779c8 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -703,7 +703,7 @@ void user_enable_single_step(struct task_struct *task)
 
         if (regs != NULL) {
 #if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
-                task->thread.dbcr0 = DBCR0_IDM | DBCR0_IC;
+                task->thread.dbcr0 |= DBCR0_IDM | DBCR0_IC;
                 regs->msr |= MSR_DE;
 #else
                 regs->msr |= MSR_SE;
@@ -716,9 +716,16 @@ void user_disable_single_step(struct task_struct *task)
 {
         struct pt_regs *regs = task->thread.regs;
 
+
+#if defined(CONFIG_44x) || defined(CONFIG_BOOKE)
+        /* If DAC then do not single step, skip */
+        if (task->thread.dabr)
+                return;
+#endif
+
         if (regs != NULL) {
 #if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
-                task->thread.dbcr0 = 0;
+                task->thread.dbcr0 &= ~(DBCR0_IC | DBCR0_IDM);
                 regs->msr &= ~MSR_DE;
 #else
                 regs->msr &= ~MSR_SE;
@@ -727,22 +734,75 @@ void user_disable_single_step(struct task_struct *task)
         clear_tsk_thread_flag(task, TIF_SINGLESTEP);
 }
 
-static int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
+int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
                                unsigned long data)
 {
-        /* We only support one DABR and no IABRS at the moment */
+        /* For ppc64 we support one DABR and no IABR's at the moment (ppc64).
+         *  For embedded processors we support one DAC and no IAC's at the
+         *  moment.
+         */
         if (addr > 0)
                 return -EINVAL;
 
-        /* The bottom 3 bits are flags */
         if ((data & ~0x7UL) >= TASK_SIZE)
                 return -EIO;
 
-        /* Ensure translation is on */
+#ifdef CONFIG_PPC64
+
+        /* For processors using DABR (i.e. 970), the bottom 3 bits are flags.
+         *  It was assumed, on previous implementations, that 3 bits were
+         *  passed together with the data address, fitting the design of the
+         *  DABR register, as follows:
+         *
+         *  bit 0: Read flag
+         *  bit 1: Write flag
+         *  bit 2: Breakpoint translation
+         *
+         *  Thus, we use them here as so.
+         */
+
+        /* Ensure breakpoint translation bit is set */
         if (data && !(data & DABR_TRANSLATION))
                 return -EIO;
 
+        /* Move contents to the DABR register */
         task->thread.dabr = data;
+
+#endif
+#if defined(CONFIG_44x) || defined(CONFIG_BOOKE)
+
+        /* As described above, it was assumed 3 bits were passed with the data
+         *  address, but we will assume only the mode bits will be passed
+         *  as to not cause alignment restrictions for DAC-based processors.
+         */
+
+        /* DAC's hold the whole address without any mode flags */
+        task->thread.dabr = data & ~0x3UL;
+
+        if (task->thread.dabr == 0) {
+                task->thread.dbcr0 &= ~(DBSR_DAC1R | DBSR_DAC1W | DBCR0_IDM);
+                task->thread.regs->msr &= ~MSR_DE;
+                return 0;
+        }
+
+        /* Read or Write bits must be set */
+
+        if (!(data & 0x3UL))
+                return -EINVAL;
+
+        /* Set the Internal Debugging flag (IDM bit 1) for the DBCR0
+           register */
+        task->thread.dbcr0 = DBCR0_IDM;
+
+        /* Check for write and read flags and set DBCR0
+           accordingly */
+        if (data & 0x1UL)
+                task->thread.dbcr0 |= DBSR_DAC1R;
+        if (data & 0x2UL)
+                task->thread.dbcr0 |= DBSR_DAC1W;
+
+        task->thread.regs->msr |= MSR_DE;
+#endif
         return 0;
 }