cdrom: Fix info leak/OOB read in cdrom_ioctl_drive_status

[mirror_ubuntu-bionic-kernel.git] / kernel / cpu.c

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 55471c3e1eac343eb52a7e834a2056c018015d70..f760063fb1647b73ccd91635d2b9dc3c1fb9578f 100644 (file)
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -351,23 +351,67 @@ EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
 enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED;
 EXPORT_SYMBOL_GPL(cpu_smt_control);
 
-static int __init smt_cmdline_disable(char *str)
+static bool cpu_smt_available __read_mostly;
+
+void __init cpu_smt_disable(bool force)
 {
-       cpu_smt_control = CPU_SMT_DISABLED;
-       if (str && !strcmp(str, "force")) {
+       if (cpu_smt_control == CPU_SMT_FORCE_DISABLED ||
+               cpu_smt_control == CPU_SMT_NOT_SUPPORTED)
+               return;
+
+       if (force) {
                pr_info("SMT: Force disabled\n");
                cpu_smt_control = CPU_SMT_FORCE_DISABLED;
+       } else {
+               cpu_smt_control = CPU_SMT_DISABLED;
        }
+}
+
+/*
+ * The decision whether SMT is supported can only be done after the full
+ * CPU identification. Called from architecture code before non boot CPUs
+ * are brought up.
+ */
+void __init cpu_smt_check_topology_early(void)
+{
+       if (!topology_smt_supported())
+               cpu_smt_control = CPU_SMT_NOT_SUPPORTED;
+}
+
+/*
+ * If SMT was disabled by BIOS, detect it here, after the CPUs have been
+ * brought online. This ensures the smt/l1tf sysfs entries are consistent
+ * with reality. cpu_smt_available is set to true during the bringup of non
+ * boot CPUs when a SMT sibling is detected. Note, this may overwrite
+ * cpu_smt_control's previous setting.
+ */
+void __init cpu_smt_check_topology(void)
+{
+       if (!cpu_smt_available)
+               cpu_smt_control = CPU_SMT_NOT_SUPPORTED;
+}
+
+static int __init smt_cmdline_disable(char *str)
+{
+       cpu_smt_disable(str && !strcmp(str, "force"));
        return 0;
 }
 early_param("nosmt", smt_cmdline_disable);
 
 static inline bool cpu_smt_allowed(unsigned int cpu)
 {
-       if (cpu_smt_control == CPU_SMT_ENABLED)
+       if (topology_is_primary_thread(cpu))
                return true;
 
-       if (topology_is_primary_thread(cpu))
+       /*
+        * If the CPU is not a 'primary' thread and the booted_once bit is
+        * set then the processor has SMT support. Store this information
+        * for the late check of SMT support in cpu_smt_check_topology().
+        */
+       if (per_cpu(cpuhp_state, cpu).booted_once)
+               cpu_smt_available = true;
+
+       if (cpu_smt_control == CPU_SMT_ENABLED)
                return true;
 
        /*
@@ -1991,6 +2035,15 @@ static void cpuhp_offline_cpu_device(unsigned int cpu)
        kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
 }
 
+static void cpuhp_online_cpu_device(unsigned int cpu)
+{
+       struct device *dev = get_cpu_device(cpu);
+
+       dev->offline = false;
+       /* Tell user space about the state change */
+       kobject_uevent(&dev->kobj, KOBJ_ONLINE);
+}
+
 static int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval)
 {
        int cpu, ret = 0;
@@ -2023,11 +2076,24 @@ static int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval)
        return ret;
 }
 
-static void cpuhp_smt_enable(void)
+static int cpuhp_smt_enable(void)
 {
+       int cpu, ret = 0;
+
        cpu_maps_update_begin();
        cpu_smt_control = CPU_SMT_ENABLED;
+       for_each_present_cpu(cpu) {
+               /* Skip online CPUs and CPUs on offline nodes */
+               if (cpu_online(cpu) || !node_online(cpu_to_node(cpu)))
+                       continue;
+               ret = _cpu_up(cpu, 0, CPUHP_ONLINE);
+               if (ret)
+                       break;
+               /* See comment in cpuhp_smt_disable() */
+               cpuhp_online_cpu_device(cpu);
+       }
        cpu_maps_update_done();
+       return ret;
 }
 
 static ssize_t
@@ -2058,7 +2124,7 @@ store_smt_control(struct device *dev, struct device_attribute *attr,
        if (ctrlval != cpu_smt_control) {
                switch (ctrlval) {
                case CPU_SMT_ENABLED:
-                       cpuhp_smt_enable();
+                       ret = cpuhp_smt_enable();
                        break;
                case CPU_SMT_DISABLED:
                case CPU_SMT_FORCE_DISABLED:
@@ -2095,9 +2161,6 @@ static const struct attribute_group cpuhp_smt_attr_group = {
 
 static int __init cpu_smt_state_init(void)
 {
-       if (!topology_smt_supported())
-               cpu_smt_control = CPU_SMT_NOT_SUPPORTED;
-
        return sysfs_create_group(&cpu_subsys.dev_root->kobj,
                                  &cpuhp_smt_attr_group);
 }
@@ -2216,6 +2279,6 @@ void __init boot_cpu_init(void)
  */
 void __init boot_cpu_state_init(void)
 {
-       this_cpu_write(cpuhp_state.booted_once, true);
-       this_cpu_write(cpuhp_state.state, CPUHP_ONLINE);
+       per_cpu_ptr(&cpuhp_state, smp_processor_id())->booted_once = true;
+       per_cpu_ptr(&cpuhp_state, smp_processor_id())->state = CPUHP_ONLINE;
 }