powerpc: Rework set_dabr so it can take a DABRX value as well

Rework set_dabr to take a DABRX value as well.

Both the pseries and PS3 hypervisors do some checks on the DABRX
values that are passed in the hcall.  This patch stops bogus values
from being passed to hypervisor.  Also, in the case where we are
clearing the breakpoint, where DABR and DABRX are zero, we modify the
DABRX value to make it valid so that the hcall won't fail.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index 6767445..6891d79 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -73,7 +73,7 @@
 	 * If so, DABR will be populated in single_step_dabr_instruction().
 	 */
 	if (current->thread.last_hit_ubp != bp)
-		set_dabr(info->address | info->type | DABR_TRANSLATION);
+		set_dabr(info->address | info->type | DABR_TRANSLATION, DABRX_ALL);
 
 	return 0;
 }
@@ -97,7 +97,7 @@
 	}
 
 	*slot = NULL;
-	set_dabr(0);
+	set_dabr(0, 0);
 }
 
 /*
@@ -197,7 +197,7 @@
 
 	info = counter_arch_bp(tsk->thread.last_hit_ubp);
 	regs->msr &= ~MSR_SE;
-	set_dabr(info->address | info->type | DABR_TRANSLATION);
+	set_dabr(info->address | info->type | DABR_TRANSLATION, DABRX_ALL);
 	tsk->thread.last_hit_ubp = NULL;
 }
 
@@ -215,7 +215,7 @@
 	unsigned long dar = regs->dar;
 
 	/* Disable breakpoints during exception handling */
-	set_dabr(0);
+	set_dabr(0, 0);
 
 	/*
 	 * The counter may be concurrently released but that can only
@@ -281,7 +281,7 @@
 	if (!info->extraneous_interrupt)
 		perf_bp_event(bp, regs);
 
-	set_dabr(info->address | info->type | DABR_TRANSLATION);
+	set_dabr(info->address | info->type | DABR_TRANSLATION, DABRX_ALL);
 out:
 	rcu_read_unlock();
 	return rc;
@@ -313,7 +313,7 @@
 	if (!info->extraneous_interrupt)
 		perf_bp_event(bp, regs);
 
-	set_dabr(info->address | info->type | DABR_TRANSLATION);
+	set_dabr(info->address | info->type | DABR_TRANSLATION, DABRX_ALL);
 	current->thread.last_hit_ubp = NULL;
 
 	/*
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 2e743de..50e504c 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -285,7 +285,7 @@
 		return;
 
 	/* Clear the DABR */
-	set_dabr(0);
+	set_dabr(0, 0);
 
 	/* Deliver the signal to userspace */
 	info.si_signo = SIGTRAP;
@@ -366,18 +366,19 @@
 {
 	if (thread->dabr) {
 		thread->dabr = 0;
-		set_dabr(0);
+		thread->dabrx = 0;
+		set_dabr(0, 0);
 	}
 }
 #endif /* !CONFIG_HAVE_HW_BREAKPOINT */
 #endif	/* CONFIG_PPC_ADV_DEBUG_REGS */
 
-int set_dabr(unsigned long dabr)
+int set_dabr(unsigned long dabr, unsigned long dabrx)
 {
 	__get_cpu_var(current_dabr) = dabr;
 
 	if (ppc_md.set_dabr)
-		return ppc_md.set_dabr(dabr);
+		return ppc_md.set_dabr(dabr, dabrx);
 
 	/* XXX should we have a CPU_FTR_HAS_DABR ? */
 #ifdef CONFIG_PPC_ADV_DEBUG_REGS
@@ -387,9 +388,8 @@
 #endif
 #elif defined(CONFIG_PPC_BOOK3S)
 	mtspr(SPRN_DABR, dabr);
+	mtspr(SPRN_DABRX, dabrx);
 #endif
-
-
 	return 0;
 }
 
@@ -482,7 +482,7 @@
  */
 #ifndef CONFIG_HAVE_HW_BREAKPOINT
 	if (unlikely(__get_cpu_var(current_dabr) != new->thread.dabr))
-		set_dabr(new->thread.dabr);
+		set_dabr(new->thread.dabr, new->thread.dabrx);
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
 #endif
 
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index c10fc28..79d8e56 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -960,6 +960,7 @@
 		thread->ptrace_bps[0] = bp;
 		ptrace_put_breakpoints(task);
 		thread->dabr = data;
+		thread->dabrx = DABRX_ALL;
 		return 0;
 	}
 
@@ -983,6 +984,7 @@
 
 	/* Move contents to the DABR register */
 	task->thread.dabr = data;
+	task->thread.dabrx = DABRX_ALL;
 #else /* CONFIG_PPC_ADV_DEBUG_REGS */
 	/* 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
@@ -1397,6 +1399,7 @@
 		dabr |= DABR_DATA_WRITE;
 
 	child->thread.dabr = dabr;
+	child->thread.dabrx = DABRX_ALL;
 
 	return 1;
 #endif /* !CONFIG_PPC_ADV_DEBUG_DVCS */
diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
index 29be271..a2dc757 100644
--- a/arch/powerpc/kernel/signal.c
+++ b/arch/powerpc/kernel/signal.c
@@ -131,7 +131,7 @@
 	 * triggered inside the kernel.
 	 */
 	if (current->thread.dabr)
-		set_dabr(current->thread.dabr);
+		set_dabr(current->thread.dabr, current->thread.dabrx);
 #endif
 	/* Re-enable the breakpoints for the signal stack */
 	thread_change_pc(current, regs);