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071c44e427
Before commit 076cbf5d2163 ("x86/xen: don't let xen_pv_play_dead()
return"), in Xen, when a previously offlined CPU was brought back
online, it unexpectedly resumed execution where it left off in the
middle of the idle loop.
There were some hacks to make that work, but the behavior was surprising
as do_idle() doesn't expect an offlined CPU to return from the dead (in
arch_cpu_idle_dead()).
Now that Xen has been fixed, and the arch-specific implementations of
arch_cpu_idle_dead() also don't return, give it a __noreturn attribute.
This will cause the compiler to complain if an arch-specific
implementation might return. It also improves code generation for both
caller and callee.
Also fixes the following warning:
vmlinux.o: warning: objtool: do_idle+0x25f: unreachable instruction
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/r/60d527353da8c99d4cf13b6473131d46719ed16d.1676358308.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
232 lines
7.4 KiB
C
232 lines
7.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* include/linux/cpu.h - generic cpu definition
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*
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* This is mainly for topological representation. We define the
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* basic 'struct cpu' here, which can be embedded in per-arch
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* definitions of processors.
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*
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* Basic handling of the devices is done in drivers/base/cpu.c
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*
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* CPUs are exported via sysfs in the devices/system/cpu
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* directory.
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*/
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#ifndef _LINUX_CPU_H_
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#define _LINUX_CPU_H_
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#include <linux/node.h>
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#include <linux/compiler.h>
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#include <linux/cpumask.h>
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#include <linux/cpuhotplug.h>
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struct device;
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struct device_node;
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struct attribute_group;
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struct cpu {
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int node_id; /* The node which contains the CPU */
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int hotpluggable; /* creates sysfs control file if hotpluggable */
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struct device dev;
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};
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extern void boot_cpu_init(void);
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extern void boot_cpu_hotplug_init(void);
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extern void cpu_init(void);
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extern void trap_init(void);
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extern int register_cpu(struct cpu *cpu, int num);
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extern struct device *get_cpu_device(unsigned cpu);
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extern bool cpu_is_hotpluggable(unsigned cpu);
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extern bool arch_match_cpu_phys_id(int cpu, u64 phys_id);
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extern bool arch_find_n_match_cpu_physical_id(struct device_node *cpun,
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int cpu, unsigned int *thread);
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extern int cpu_add_dev_attr(struct device_attribute *attr);
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extern void cpu_remove_dev_attr(struct device_attribute *attr);
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extern int cpu_add_dev_attr_group(struct attribute_group *attrs);
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extern void cpu_remove_dev_attr_group(struct attribute_group *attrs);
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extern ssize_t cpu_show_meltdown(struct device *dev,
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struct device_attribute *attr, char *buf);
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extern ssize_t cpu_show_spectre_v1(struct device *dev,
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struct device_attribute *attr, char *buf);
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extern ssize_t cpu_show_spectre_v2(struct device *dev,
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struct device_attribute *attr, char *buf);
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extern ssize_t cpu_show_spec_store_bypass(struct device *dev,
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struct device_attribute *attr, char *buf);
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extern ssize_t cpu_show_l1tf(struct device *dev,
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struct device_attribute *attr, char *buf);
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extern ssize_t cpu_show_mds(struct device *dev,
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struct device_attribute *attr, char *buf);
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extern ssize_t cpu_show_tsx_async_abort(struct device *dev,
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struct device_attribute *attr,
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char *buf);
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extern ssize_t cpu_show_itlb_multihit(struct device *dev,
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struct device_attribute *attr, char *buf);
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extern ssize_t cpu_show_srbds(struct device *dev, struct device_attribute *attr, char *buf);
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extern ssize_t cpu_show_mmio_stale_data(struct device *dev,
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struct device_attribute *attr,
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char *buf);
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extern ssize_t cpu_show_retbleed(struct device *dev,
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struct device_attribute *attr, char *buf);
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extern __printf(4, 5)
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struct device *cpu_device_create(struct device *parent, void *drvdata,
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const struct attribute_group **groups,
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const char *fmt, ...);
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#ifdef CONFIG_HOTPLUG_CPU
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extern void unregister_cpu(struct cpu *cpu);
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extern ssize_t arch_cpu_probe(const char *, size_t);
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extern ssize_t arch_cpu_release(const char *, size_t);
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#endif
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/*
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* These states are not related to the core CPU hotplug mechanism. They are
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* used by various (sub)architectures to track internal state
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*/
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#define CPU_ONLINE 0x0002 /* CPU is up */
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#define CPU_UP_PREPARE 0x0003 /* CPU coming up */
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#define CPU_DEAD 0x0007 /* CPU dead */
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#define CPU_DEAD_FROZEN 0x0008 /* CPU timed out on unplug */
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#define CPU_POST_DEAD 0x0009 /* CPU successfully unplugged */
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#define CPU_BROKEN 0x000B /* CPU did not die properly */
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#ifdef CONFIG_SMP
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extern bool cpuhp_tasks_frozen;
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int add_cpu(unsigned int cpu);
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int cpu_device_up(struct device *dev);
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void notify_cpu_starting(unsigned int cpu);
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extern void cpu_maps_update_begin(void);
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extern void cpu_maps_update_done(void);
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int bringup_hibernate_cpu(unsigned int sleep_cpu);
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void bringup_nonboot_cpus(unsigned int setup_max_cpus);
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#else /* CONFIG_SMP */
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#define cpuhp_tasks_frozen 0
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static inline void cpu_maps_update_begin(void)
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{
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}
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static inline void cpu_maps_update_done(void)
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{
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}
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static inline int add_cpu(unsigned int cpu) { return 0;}
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#endif /* CONFIG_SMP */
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extern struct bus_type cpu_subsys;
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extern int lockdep_is_cpus_held(void);
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#ifdef CONFIG_HOTPLUG_CPU
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extern void cpus_write_lock(void);
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extern void cpus_write_unlock(void);
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extern void cpus_read_lock(void);
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extern void cpus_read_unlock(void);
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extern int cpus_read_trylock(void);
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extern void lockdep_assert_cpus_held(void);
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extern void cpu_hotplug_disable(void);
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extern void cpu_hotplug_enable(void);
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void clear_tasks_mm_cpumask(int cpu);
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int remove_cpu(unsigned int cpu);
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int cpu_device_down(struct device *dev);
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extern void smp_shutdown_nonboot_cpus(unsigned int primary_cpu);
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#else /* CONFIG_HOTPLUG_CPU */
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static inline void cpus_write_lock(void) { }
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static inline void cpus_write_unlock(void) { }
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static inline void cpus_read_lock(void) { }
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static inline void cpus_read_unlock(void) { }
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static inline int cpus_read_trylock(void) { return true; }
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static inline void lockdep_assert_cpus_held(void) { }
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static inline void cpu_hotplug_disable(void) { }
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static inline void cpu_hotplug_enable(void) { }
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static inline int remove_cpu(unsigned int cpu) { return -EPERM; }
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static inline void smp_shutdown_nonboot_cpus(unsigned int primary_cpu) { }
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#endif /* !CONFIG_HOTPLUG_CPU */
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#ifdef CONFIG_PM_SLEEP_SMP
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extern int freeze_secondary_cpus(int primary);
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extern void thaw_secondary_cpus(void);
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static inline int suspend_disable_secondary_cpus(void)
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{
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int cpu = 0;
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if (IS_ENABLED(CONFIG_PM_SLEEP_SMP_NONZERO_CPU))
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cpu = -1;
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return freeze_secondary_cpus(cpu);
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}
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static inline void suspend_enable_secondary_cpus(void)
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{
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return thaw_secondary_cpus();
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}
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#else /* !CONFIG_PM_SLEEP_SMP */
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static inline void thaw_secondary_cpus(void) {}
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static inline int suspend_disable_secondary_cpus(void) { return 0; }
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static inline void suspend_enable_secondary_cpus(void) { }
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#endif /* !CONFIG_PM_SLEEP_SMP */
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void __noreturn cpu_startup_entry(enum cpuhp_state state);
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void cpu_idle_poll_ctrl(bool enable);
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bool cpu_in_idle(unsigned long pc);
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void arch_cpu_idle(void);
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void arch_cpu_idle_prepare(void);
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void arch_cpu_idle_enter(void);
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void arch_cpu_idle_exit(void);
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void __noreturn arch_cpu_idle_dead(void);
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int cpu_report_state(int cpu);
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int cpu_check_up_prepare(int cpu);
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void cpu_set_state_online(int cpu);
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void play_idle_precise(u64 duration_ns, u64 latency_ns);
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static inline void play_idle(unsigned long duration_us)
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{
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play_idle_precise(duration_us * NSEC_PER_USEC, U64_MAX);
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}
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#ifdef CONFIG_HOTPLUG_CPU
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bool cpu_wait_death(unsigned int cpu, int seconds);
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bool cpu_report_death(void);
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void cpuhp_report_idle_dead(void);
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#else
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static inline void cpuhp_report_idle_dead(void) { }
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#endif /* #ifdef CONFIG_HOTPLUG_CPU */
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enum cpuhp_smt_control {
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CPU_SMT_ENABLED,
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CPU_SMT_DISABLED,
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CPU_SMT_FORCE_DISABLED,
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CPU_SMT_NOT_SUPPORTED,
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CPU_SMT_NOT_IMPLEMENTED,
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};
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#if defined(CONFIG_SMP) && defined(CONFIG_HOTPLUG_SMT)
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extern enum cpuhp_smt_control cpu_smt_control;
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extern void cpu_smt_disable(bool force);
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extern void cpu_smt_check_topology(void);
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extern bool cpu_smt_possible(void);
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extern int cpuhp_smt_enable(void);
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extern int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval);
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#else
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# define cpu_smt_control (CPU_SMT_NOT_IMPLEMENTED)
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static inline void cpu_smt_disable(bool force) { }
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static inline void cpu_smt_check_topology(void) { }
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static inline bool cpu_smt_possible(void) { return false; }
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static inline int cpuhp_smt_enable(void) { return 0; }
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static inline int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval) { return 0; }
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#endif
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extern bool cpu_mitigations_off(void);
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extern bool cpu_mitigations_auto_nosmt(void);
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#endif /* _LINUX_CPU_H_ */
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