powerpc: Hardware breakpoints rewrite to handle non DABR breakpoint registers

This is a rewrite so that we don't assume we are using the DABR throughout the
code.  We now use the arch_hw_breakpoint to store the breakpoint in a generic
manner in the thread_struct, rather than storing the raw DABR value.

The ptrace GET/SET_DEBUGREG interface currently passes the raw DABR in from
userspace.  We keep this functionality, so that future changes (like the POWER8
DAWR), will still fake the DABR to userspace.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 30 insertions, 42 deletions

diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c
index a89cae481b04..c7483d09fdd0 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -73,7 +73,7 @@ int arch_install_hw_breakpoint(struct perf_event *bp)
 	 * 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, info->dabrx);
+		set_break(info);
 
 	return 0;
 }
@@ -97,7 +97,7 @@ void arch_uninstall_hw_breakpoint(struct perf_event *bp)
 	}
 
 	*slot = NULL;
-	set_dabr(0, 0);
+	hw_breakpoint_disable();
 }
 
 /*
@@ -127,19 +127,13 @@ int arch_check_bp_in_kernelspace(struct perf_event *bp)
 
 int arch_bp_generic_fields(int type, int *gen_bp_type)
 {
-	switch (type) {
-	case DABR_DATA_READ:
-		*gen_bp_type = HW_BREAKPOINT_R;
-		break;
-	case DABR_DATA_WRITE:
-		*gen_bp_type = HW_BREAKPOINT_W;
-		break;
-	case (DABR_DATA_WRITE | DABR_DATA_READ):
-		*gen_bp_type = (HW_BREAKPOINT_W | HW_BREAKPOINT_R);
-		break;
-	default:
+	*gen_bp_type = 0;
+	if (type & HW_BRK_TYPE_READ)
+		*gen_bp_type |= HW_BREAKPOINT_R;
+	if (type & HW_BRK_TYPE_WRITE)
+		*gen_bp_type |= HW_BREAKPOINT_W;
+	if (*gen_bp_type == 0)
 		return -EINVAL;
-	}
 	return 0;
 }
 
@@ -154,29 +148,22 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
 	if (!bp)
 		return ret;
 
-	switch (bp->attr.bp_type) {
-	case HW_BREAKPOINT_R:
-		info->type = DABR_DATA_READ;
-		break;
-	case HW_BREAKPOINT_W:
-		info->type = DABR_DATA_WRITE;
-		break;
-	case HW_BREAKPOINT_R | HW_BREAKPOINT_W:
-		info->type = (DABR_DATA_READ | DABR_DATA_WRITE);
-		break;
-	default:
+	info->type = HW_BRK_TYPE_TRANSLATE;
+	if (bp->attr.bp_type & HW_BREAKPOINT_R)
+		info->type |= HW_BRK_TYPE_READ;
+	if (bp->attr.bp_type & HW_BREAKPOINT_W)
+		info->type |= HW_BRK_TYPE_WRITE;
+	if (info->type == HW_BRK_TYPE_TRANSLATE)
+		/* must set alteast read or write */
 		return ret;
-	}
-
+	if (!(bp->attr.exclude_user))
+		info->type |= HW_BRK_TYPE_USER;
+	if (!(bp->attr.exclude_kernel))
+		info->type |= HW_BRK_TYPE_KERNEL;
+	if (!(bp->attr.exclude_hv))
+		info->type |= HW_BRK_TYPE_HYP;
 	info->address = bp->attr.bp_addr;
 	info->len = bp->attr.bp_len;
-	info->dabrx = DABRX_ALL;
-	if (bp->attr.exclude_user)
-		info->dabrx &= ~DABRX_USER;
-	if (bp->attr.exclude_kernel)
-		info->dabrx &= ~DABRX_KERNEL;
-	if (bp->attr.exclude_hv)
-		info->dabrx &= ~DABRX_HYP;
 
 	/*
 	 * Since breakpoint length can be a maximum of HW_BREAKPOINT_LEN(8)
@@ -204,7 +191,7 @@ void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs)
 
 	info = counter_arch_bp(tsk->thread.last_hit_ubp);
 	regs->msr &= ~MSR_SE;
-	set_dabr(info->address | info->type | DABR_TRANSLATION, info->dabrx);
+	set_break(info);
 	tsk->thread.last_hit_ubp = NULL;
 }
 
@@ -222,7 +209,7 @@ int __kprobes hw_breakpoint_handler(struct die_args *args)
 	unsigned long dar = regs->dar;
 
 	/* Disable breakpoints during exception handling */
-	set_dabr(0, 0);
+	hw_breakpoint_disable();
 
 	/*
 	 * The counter may be concurrently released but that can only
@@ -255,8 +242,9 @@ int __kprobes hw_breakpoint_handler(struct die_args *args)
 	 * we still need to single-step the instruction, but we don't
 	 * generate an event.
 	 */
-	info->extraneous_interrupt = !((bp->attr.bp_addr <= dar) &&
-			(dar - bp->attr.bp_addr < bp->attr.bp_len));
+	if (!((bp->attr.bp_addr <= dar) &&
+	      (dar - bp->attr.bp_addr < bp->attr.bp_len)))
+		info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;
 
 	/* Do not emulate user-space instructions, instead single-step them */
 	if (user_mode(regs)) {
@@ -285,10 +273,10 @@ int __kprobes hw_breakpoint_handler(struct die_args *args)
 	 * As a policy, the callback is invoked in a 'trigger-after-execute'
 	 * fashion
 	 */
-	if (!info->extraneous_interrupt)
+	if (!(info->type & HW_BRK_TYPE_EXTRANEOUS_IRQ))
 		perf_bp_event(bp, regs);
 
-	set_dabr(info->address | info->type | DABR_TRANSLATION, info->dabrx);
+	set_break(info);
 out:
 	rcu_read_unlock();
 	return rc;
@@ -317,10 +305,10 @@ int __kprobes single_step_dabr_instruction(struct die_args *args)
 	 * We shall invoke the user-defined callback function in the single
 	 * stepping handler to confirm to 'trigger-after-execute' semantics
 	 */
-	if (!info->extraneous_interrupt)
+	if (!(info->type & HW_BRK_TYPE_EXTRANEOUS_IRQ))
 		perf_bp_event(bp, regs);
 
-	set_dabr(info->address | info->type | DABR_TRANSLATION, info->dabrx);
+	set_break(info);
 	current->thread.last_hit_ubp = NULL;
 
 	/*