5 files changed, 136 insertions, 10 deletions

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index da52269aec1e..81c8324a4a3c 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -148,7 +148,7 @@ transfer_to_handler:
         /* Check to see if the dbcr0 register is set up to debug.  Use the
            internal debug mode bit to do this. */
         lwz     r12,THREAD_DBCR0(r12)
-        andis.  r12,r12,DBCR0_IDM@h
+        andis.  r12,r12,(DBCR0_IDM  | DBSR_DAC1R | DBSR_DAC1W)@h
         beq+    3f
         /* From user and task is ptraced - load up global dbcr0 */
         li      r12,-1                  /* clear all pending debug events */
@@ -292,7 +292,7 @@ syscall_exit_cont:
         /* If the process has its own DBCR0 value, load it up.  The internal
            debug mode bit tells us that dbcr0 should be loaded. */
         lwz     r0,THREAD+THREAD_DBCR0(r2)
-        andis.  r10,r0,DBCR0_IDM@h
+        andis.  r10,r0,(DBCR0_IDM  | DBSR_DAC1R | DBSR_DAC1W)@h
         bnel-   load_dbcr0
 #endif
 #ifdef CONFIG_44x
@@ -720,7 +720,7 @@ restore_user:
         /* Check whether this process has its own DBCR0 value.  The internal
            debug mode bit tells us that dbcr0 should be loaded. */
         lwz     r0,THREAD+THREAD_DBCR0(r2)
-        andis.  r10,r0,DBCR0_IDM@h
+        andis.  r10,r0,(DBCR0_IDM  | DBSR_DAC1R | DBSR_DAC1W)@h
         bnel-   load_dbcr0
 #endif
 
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 219f3634115e..db2497ccc111 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -47,6 +47,8 @@
 #ifdef CONFIG_PPC64
 #include <asm/firmware.h>
 #endif
+#include <linux/kprobes.h>
+#include <linux/kdebug.h>
 
 extern unsigned long _get_SP(void);
 
@@ -239,6 +241,35 @@ void discard_lazy_cpu_state(void)
 }
 #endif /* CONFIG_SMP */
 
+void do_dabr(struct pt_regs *regs, unsigned long address,
+                    unsigned long error_code)
+{
+        siginfo_t info;
+
+        if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,
+                        11, SIGSEGV) == NOTIFY_STOP)
+                return;
+
+        if (debugger_dabr_match(regs))
+                return;
+
+        /* Clear the DAC and struct entries.  One shot trigger */
+#if (defined(CONFIG_44x) || defined(CONFIG_BOOKE))
+        mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) & ~(DBSR_DAC1R | DBSR_DAC1W
+                                                        | DBCR0_IDM));
+#endif
+
+        /* Clear the DABR */
+        set_dabr(0);
+
+        /* Deliver the signal to userspace */
+        info.si_signo = SIGTRAP;
+        info.si_errno = 0;
+        info.si_code = TRAP_HWBKPT;
+        info.si_addr = (void __user *)address;
+        force_sig_info(SIGTRAP, &info, current);
+}
+
 static DEFINE_PER_CPU(unsigned long, current_dabr);
 
 int set_dabr(unsigned long dabr)
@@ -254,6 +285,11 @@ int set_dabr(unsigned long dabr)
 #if defined(CONFIG_PPC64) || defined(CONFIG_6xx)
         mtspr(SPRN_DABR, dabr);
 #endif
+
+#if defined(CONFIG_44x) || defined(CONFIG_BOOKE)
+        mtspr(SPRN_DAC1, dabr);
+#endif
+
         return 0;
 }
 
@@ -337,6 +373,12 @@ struct task_struct *__switch_to(struct task_struct *prev,
         if (unlikely(__get_cpu_var(current_dabr) != new->thread.dabr))
                 set_dabr(new->thread.dabr);
 
+#if defined(CONFIG_44x) || defined(CONFIG_BOOKE)
+        /* If new thread DAC (HW breakpoint) is the same then leave it */
+        if (new->thread.dabr)
+                set_dabr(new->thread.dabr);
+#endif
+
         new_thread = &new->thread;
         old_thread = &current->thread;
 
@@ -525,6 +567,10 @@ void flush_thread(void)
         if (current->thread.dabr) {
                 current->thread.dabr = 0;
                 set_dabr(0);
+
+#if defined(CONFIG_44x) || defined(CONFIG_BOOKE)
+                current->thread.dbcr0 &= ~(DBSR_DAC1R | DBSR_DAC1W);
+#endif
         }
 }
 
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;
 }
 
diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
index ad55488939c3..7aada783ec6a 100644
--- a/arch/powerpc/kernel/signal.c
+++ b/arch/powerpc/kernel/signal.c
@@ -145,8 +145,12 @@ int do_signal(sigset_t *oldset, struct pt_regs *regs)
          * user space. The DABR will have been cleared if it
          * triggered inside the kernel.
          */
-        if (current->thread.dabr)
+        if (current->thread.dabr) {
                 set_dabr(current->thread.dabr);
+#if defined(CONFIG_44x) || defined(CONFIG_BOOKE)
+                mtspr(SPRN_DBCR0, current->thread.dbcr0);
+#endif
+        }
 
         if (is32) {
                 if (ka.sa.sa_flags & SA_SIGINFO)
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 878fbddb6ae1..81ccb8dd1a54 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1067,6 +1067,22 @@ void __kprobes DebugException(struct pt_regs *regs, unsigned long debug_status)
                 }
 
                 _exception(SIGTRAP, regs, TRAP_TRACE, regs->nip);
+        } else if (debug_status & (DBSR_DAC1R | DBSR_DAC1W)) {
+                regs->msr &= ~MSR_DE;
+
+                if (user_mode(regs)) {
+                        current->thread.dbcr0 &= ~(DBSR_DAC1R | DBSR_DAC1W |
+                                                                DBCR0_IDM);
+                } else {
+                        /* Disable DAC interupts */
+                        mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) & ~(DBSR_DAC1R |
+                                                DBSR_DAC1W | DBCR0_IDM));
+
+                        /* Clear the DAC event */
+                        mtspr(SPRN_DBSR, (DBSR_DAC1R | DBSR_DAC1W));
+                }
+                /* Setup and send the trap to the handler */
+                do_dabr(regs, mfspr(SPRN_DAC1), debug_status);
         }
 }
 #endif /* CONFIG_4xx || CONFIG_BOOKE */