powerpc: Dynamically calculate the dabrx based on kernel/user/hypervisor

Currently we mark the DABRX to interrupt on all matches
(hypervisor/kernel/user and then filter in software.  We can be a lot
smarter now that we can set the DABRX dynamically.

This sets the DABRX based on the flags passed by the user.

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

arch/powerpc/include/asm/hw_breakpoint.h

@@ -28,6 +28,7 @@
 
 struct arch_hw_breakpoint {
 	unsigned long	address;
+	unsigned long	dabrx;
 	int		type;
 	u8		len; /* length of the target data symbol */
 	bool		extraneous_interrupt;

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, DABRX_ALL);
+		set_dabr(info->address | info->type | DABR_TRANSLATION, info->dabrx);
 
 	return 0;
 }
@@ -170,6 +170,13 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
 
 	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)
@@ -197,7 +204,7 @@ 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, DABRX_ALL);
+	set_dabr(info->address | info->type | DABR_TRANSLATION, info->dabrx);
 	tsk->thread.last_hit_ubp = NULL;
 }
 
@@ -281,7 +288,7 @@ int __kprobes hw_breakpoint_handler(struct die_args *args)
 	if (!info->extraneous_interrupt)
 		perf_bp_event(bp, regs);
 
-	set_dabr(info->address | info->type | DABR_TRANSLATION, DABRX_ALL);
+	set_dabr(info->address | info->type | DABR_TRANSLATION, info->dabrx);
 out:
 	rcu_read_unlock();
 	return rc;
@@ -313,7 +320,7 @@ int __kprobes single_step_dabr_instruction(struct die_args *args)
 	if (!info->extraneous_interrupt)
 		perf_bp_event(bp, regs);
 
-	set_dabr(info->address | info->type | DABR_TRANSLATION, DABRX_ALL);
+	set_dabr(info->address | info->type | DABR_TRANSLATION, info->dabrx);
 	current->thread.last_hit_ubp = NULL;
 
 	/*

arch/powerpc/platforms/pseries/setup.c

@@ -425,7 +425,7 @@ static int pseries_set_xdabr(unsigned long dabr, unsigned long dabrx)
 	if (dabrx == 0 && dabr == 0)
 		dabrx = DABRX_USER;
 	/* PAPR says we can only set kernel and user bits */
-	dabrx &= H_DABRX_KERNEL | H_DABRX_USER;
+	dabrx &= DABRX_KERNEL | DABRX_USER;
 
 	return plpar_hcall_norets(H_SET_XDABR, dabr, dabrx);
 }