powerpc/watchpoint/xmon: Support 2nd DAWR

Add support for 2nd DAWR in xmon. With this, we can have two
simultaneous breakpoints from xmon.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Michael Neuling <mikey@neuling.org>
Link: https://lore.kernel.org/r/20200514111741.97993-17-ravi.bangoria@linux.ibm.com

arch/powerpc/xmon/xmon.c

@@ -112,7 +112,7 @@ struct bpt {
 #define BP_DABR		4
 
 static struct bpt bpts[NBPTS];
-static struct bpt dabr;
+static struct bpt dabr[HBP_NUM_MAX];
 static struct bpt *iabr;
 static unsigned bpinstr = 0x7fe00008;	/* trap */
 
@@ -784,10 +784,17 @@ static int xmon_sstep(struct pt_regs *regs)
 
 static int xmon_break_match(struct pt_regs *regs)
 {
+	int i;
+
 	if ((regs->msr & (MSR_IR|MSR_PR|MSR_64BIT)) != (MSR_IR|MSR_64BIT))
 		return 0;
-	if (dabr.enabled == 0)
+	for (i = 0; i < nr_wp_slots(); i++) {
+		if (dabr[i].enabled)
+			goto found;
+	}
 	return 0;
+
+found:
 	xmon_core(regs, 0);
 	return 1;
 }
@@ -948,13 +955,16 @@ static void insert_bpts(void)
 
 static void insert_cpu_bpts(void)
 {
+	int i;
 	struct arch_hw_breakpoint brk;
 
-	if (dabr.enabled) {
-		brk.address = dabr.address;
-		brk.type = (dabr.enabled & HW_BRK_TYPE_DABR) | HW_BRK_TYPE_PRIV_ALL;
-		brk.len = DABR_MAX_LEN;
-		__set_breakpoint(0, &brk);
+	for (i = 0; i < nr_wp_slots(); i++) {
+		if (dabr[i].enabled) {
+			brk.address = dabr[i].address;
+			brk.type = (dabr[i].enabled & HW_BRK_TYPE_DABR) | HW_BRK_TYPE_PRIV_ALL;
+			brk.len = 8;
+			__set_breakpoint(i, &brk);
+		}
 	}
 
 	if (iabr)
@@ -1366,6 +1376,35 @@ static long check_bp_loc(unsigned long addr)
 	return 1;
 }
 
+static int find_free_data_bpt(void)
+{
+	int i;
+
+	for (i = 0; i < nr_wp_slots(); i++) {
+		if (!dabr[i].enabled)
+			return i;
+	}
+	printf("Couldn't find free breakpoint register\n");
+	return -1;
+}
+
+static void print_data_bpts(void)
+{
+	int i;
+
+	for (i = 0; i < nr_wp_slots(); i++) {
+		if (!dabr[i].enabled)
+			continue;
+
+		printf("   data   "REG"  [", dabr[i].address);
+		if (dabr[i].enabled & 1)
+			printf("r");
+		if (dabr[i].enabled & 2)
+			printf("w");
+		printf("]\n");
+	}
+}
+
 static char *breakpoint_help_string =
     "Breakpoint command usage:\n"
     "b                show breakpoints\n"
@@ -1399,10 +1438,9 @@ bpt_cmds(void)
 			printf("Hardware data breakpoint not supported on this cpu\n");
 			break;
 		}
-		if (dabr.enabled) {
-			printf("Couldn't find free breakpoint register\n");
+		i = find_free_data_bpt();
+		if (i < 0)
 			break;
-		}
 		mode = 7;
 		cmd = inchar();
 		if (cmd == 'r')
@@ -1411,15 +1449,15 @@ bpt_cmds(void)
 			mode = 6;
 		else
 			termch = cmd;
-		dabr.address = 0;
-		dabr.enabled = 0;
-		if (scanhex(&dabr.address)) {
-			if (!is_kernel_addr(dabr.address)) {
+		dabr[i].address = 0;
+		dabr[i].enabled = 0;
+		if (scanhex(&dabr[i].address)) {
+			if (!is_kernel_addr(dabr[i].address)) {
 				printf(badaddr);
 				break;
 			}
-			dabr.address &= ~HW_BRK_TYPE_DABR;
-			dabr.enabled = mode | BP_DABR;
+			dabr[i].address &= ~HW_BRK_TYPE_DABR;
+			dabr[i].enabled = mode | BP_DABR;
 		}
 
 		force_enable_xmon();
@@ -1458,7 +1496,9 @@ bpt_cmds(void)
 			for (i = 0; i < NBPTS; ++i)
 				bpts[i].enabled = 0;
 			iabr = NULL;
-			dabr.enabled = 0;
+			for (i = 0; i < nr_wp_slots(); i++)
+				dabr[i].enabled = 0;
+
 			printf("All breakpoints cleared\n");
 			break;
 		}
@@ -1492,14 +1532,7 @@ bpt_cmds(void)
 		if (xmon_is_ro || !scanhex(&a)) {
 			/* print all breakpoints */
 			printf("   type            address\n");
-			if (dabr.enabled) {
-				printf("   data   "REG"  [", dabr.address);
-				if (dabr.enabled & 1)
-					printf("r");
-				if (dabr.enabled & 2)
-					printf("w");
-				printf("]\n");
-			}
+			print_data_bpts();
 			for (bp = bpts; bp < &bpts[NBPTS]; ++bp) {
 				if (!bp->enabled)
 					continue;
@@ -1959,8 +1992,13 @@ static void dump_207_sprs(void)
 
 	printf("hfscr  = %.16lx  dhdes = %.16lx rpr    = %.16lx\n",
 		mfspr(SPRN_HFSCR), mfspr(SPRN_DHDES), mfspr(SPRN_RPR));
-	printf("dawr   = %.16lx  dawrx = %.16lx ciabr  = %.16lx\n",
-		mfspr(SPRN_DAWR0), mfspr(SPRN_DAWRX0), mfspr(SPRN_CIABR));
+	printf("dawr0  = %.16lx dawrx0 = %.16lx\n",
+	       mfspr(SPRN_DAWR0), mfspr(SPRN_DAWRX0));
+	if (nr_wp_slots() > 1) {
+		printf("dawr1  = %.16lx dawrx1 = %.16lx\n",
+		       mfspr(SPRN_DAWR1), mfspr(SPRN_DAWRX1));
+	}
+	printf("ciabr  = %.16lx\n", mfspr(SPRN_CIABR));
 #endif
 }
 
@@ -3909,10 +3947,9 @@ static void clear_all_bpt(void)
 		bpts[i].enabled = 0;
 
 	/* Clear any data or iabr breakpoints */
-	if (iabr || dabr.enabled) {
 	iabr = NULL;
-		dabr.enabled = 0;
-	}
+	for (i = 0; i < nr_wp_slots(); i++)
+		dabr[i].enabled = 0;
 }
 
 #ifdef CONFIG_DEBUG_FS