MIPS: Loongson64: Test register availability before use

commit c04366b upstream.

Some global register address variable may be missing on
specific CPU type, test them before use them.

Cc: stable@vger.kernel.org
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/mips/loongson64/smp.c

@@ -466,12 +466,25 @@ static void loongson3_smp_finish(void)
 static void __init loongson3_smp_setup(void)
 {
 	int i = 0, num = 0; /* i: physical id, num: logical id */
+	int max_cpus = 0;
 
 	init_cpu_possible(cpu_none_mask);
 
+	for (i = 0; i < ARRAY_SIZE(smp_group); i++) {
+		if (!smp_group[i])
+			break;
+		max_cpus += loongson_sysconf.cores_per_node;
+	}
+
+	if (max_cpus < loongson_sysconf.nr_cpus) {
+		pr_err("SMP Groups are less than the number of CPUs\n");
+		loongson_sysconf.nr_cpus = max_cpus ? max_cpus : 1;
+	}
+
 	/* For unified kernel, NR_CPUS is the maximum possible value,
 	 * loongson_sysconf.nr_cpus is the really present value
 	 */
+	i = 0;
 	while (i < loongson_sysconf.nr_cpus) {
 		if (loongson_sysconf.reserved_cpus_mask & (1<<i)) {
 			/* Reserved physical CPU cores */
@@ -492,14 +505,14 @@ static void __init loongson3_smp_setup(void)
 		__cpu_logical_map[num] = -1;
 		num++;
 	}
-
 	csr_ipi_probe();
 	ipi_set0_regs_init();
 	ipi_clear0_regs_init();
 	ipi_status0_regs_init();
 	ipi_en0_regs_init();
 	ipi_mailbox_buf_init();
-	ipi_write_enable(0);
+	if (smp_group[0])
+		ipi_write_enable(0);
 
 	cpu_set_core(&cpu_data[0],
 		     cpu_logical_map(0) % loongson_sysconf.cores_per_package);
@@ -818,6 +831,9 @@ static int loongson3_disable_clock(unsigned int cpu)
 	uint64_t core_id = cpu_core(&cpu_data[cpu]);
 	uint64_t package_id = cpu_data[cpu].package;
 
+	if (!loongson_chipcfg[package_id] || !loongson_freqctrl[package_id])
+		return 0;
+
 	if ((read_c0_prid() & PRID_REV_MASK) == PRID_REV_LOONGSON3A_R1) {
 		LOONGSON_CHIPCFG(package_id) &= ~(1 << (12 + core_id));
 	} else {
@@ -832,6 +848,9 @@ static int loongson3_enable_clock(unsigned int cpu)
 	uint64_t core_id = cpu_core(&cpu_data[cpu]);
 	uint64_t package_id = cpu_data[cpu].package;
 
+	if (!loongson_chipcfg[package_id] || !loongson_freqctrl[package_id])
+		return 0;
+
 	if ((read_c0_prid() & PRID_REV_MASK) == PRID_REV_LOONGSON3A_R1) {
 		LOONGSON_CHIPCFG(package_id) |= 1 << (12 + core_id);
 	} else {