| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| |
| #include <linux/errno.h> |
| #include <linux/kernel.h> |
| #include <linux/mm.h> |
| #include <linux/smp.h> |
| #include <linux/prctl.h> |
| #include <linux/slab.h> |
| #include <linux/sched.h> |
| #include <linux/init.h> |
| #include <linux/export.h> |
| #include <linux/pm.h> |
| #include <linux/tick.h> |
| #include <linux/random.h> |
| #include <linux/user-return-notifier.h> |
| #include <linux/dmi.h> |
| #include <linux/utsname.h> |
| #include <linux/stackprotector.h> |
| #include <linux/tick.h> |
| #include <linux/cpuidle.h> |
| #include <trace/events/power.h> |
| #include <linux/hw_breakpoint.h> |
| #include <asm/cpu.h> |
| #include <asm/apic.h> |
| #include <asm/syscalls.h> |
| #include <asm/idle.h> |
| #include <asm/uaccess.h> |
| #include <asm/mwait.h> |
| #include <asm/fpu/internal.h> |
| #include <asm/debugreg.h> |
| #include <asm/nmi.h> |
| #include <asm/tlbflush.h> |
| #include <asm/mce.h> |
| #include <asm/vm86.h> |
| #include <asm/switch_to.h> |
| |
| /* |
| * per-CPU TSS segments. Threads are completely 'soft' on Linux, |
| * no more per-task TSS's. The TSS size is kept cacheline-aligned |
| * so they are allowed to end up in the .data..cacheline_aligned |
| * section. Since TSS's are completely CPU-local, we want them |
| * on exact cacheline boundaries, to eliminate cacheline ping-pong. |
| */ |
| __visible DEFINE_PER_CPU_SHARED_ALIGNED_USER_MAPPED(struct tss_struct, cpu_tss) = { |
| .x86_tss = { |
| .sp0 = TOP_OF_INIT_STACK, |
| #ifdef CONFIG_X86_32 |
| .ss0 = __KERNEL_DS, |
| .ss1 = __KERNEL_CS, |
| .io_bitmap_base = INVALID_IO_BITMAP_OFFSET, |
| #endif |
| }, |
| #ifdef CONFIG_X86_32 |
| /* |
| * Note that the .io_bitmap member must be extra-big. This is because |
| * the CPU will access an additional byte beyond the end of the IO |
| * permission bitmap. The extra byte must be all 1 bits, and must |
| * be within the limit. |
| */ |
| .io_bitmap = { [0 ... IO_BITMAP_LONGS] = ~0 }, |
| #endif |
| #ifdef CONFIG_X86_32 |
| .SYSENTER_stack_canary = STACK_END_MAGIC, |
| #endif |
| }; |
| EXPORT_PER_CPU_SYMBOL(cpu_tss); |
| |
| #ifdef CONFIG_X86_64 |
| static DEFINE_PER_CPU(unsigned char, is_idle); |
| #endif |
| |
| /* |
| * this gets called so that we can store lazy state into memory and copy the |
| * current task into the new thread. |
| */ |
| int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) |
| { |
| memcpy(dst, src, arch_task_struct_size); |
| #ifdef CONFIG_VM86 |
| dst->thread.vm86 = NULL; |
| #endif |
| |
| return fpu__copy(&dst->thread.fpu, &src->thread.fpu); |
| } |
| |
| /* |
| * Free current thread data structures etc.. |
| */ |
| void exit_thread(struct task_struct *tsk) |
| { |
| struct thread_struct *t = &tsk->thread; |
| unsigned long *bp = t->io_bitmap_ptr; |
| struct fpu *fpu = &t->fpu; |
| |
| if (bp) { |
| struct tss_struct *tss = &per_cpu(cpu_tss, get_cpu()); |
| |
| t->io_bitmap_ptr = NULL; |
| clear_thread_flag(TIF_IO_BITMAP); |
| /* |
| * Careful, clear this in the TSS too: |
| */ |
| memset(tss->io_bitmap, 0xff, t->io_bitmap_max); |
| t->io_bitmap_max = 0; |
| put_cpu(); |
| kfree(bp); |
| } |
| |
| free_vm86(t); |
| |
| fpu__drop(fpu); |
| } |
| |
| void flush_thread(void) |
| { |
| struct task_struct *tsk = current; |
| |
| flush_ptrace_hw_breakpoint(tsk); |
| memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array)); |
| |
| fpu__clear(&tsk->thread.fpu); |
| } |
| |
| static void hard_disable_TSC(void) |
| { |
| cr4_set_bits(X86_CR4_TSD); |
| } |
| |
| void disable_TSC(void) |
| { |
| preempt_disable(); |
| if (!test_and_set_thread_flag(TIF_NOTSC)) |
| /* |
| * Must flip the CPU state synchronously with |
| * TIF_NOTSC in the current running context. |
| */ |
| hard_disable_TSC(); |
| preempt_enable(); |
| } |
| |
| static void hard_enable_TSC(void) |
| { |
| cr4_clear_bits(X86_CR4_TSD); |
| } |
| |
| static void enable_TSC(void) |
| { |
| preempt_disable(); |
| if (test_and_clear_thread_flag(TIF_NOTSC)) |
| /* |
| * Must flip the CPU state synchronously with |
| * TIF_NOTSC in the current running context. |
| */ |
| hard_enable_TSC(); |
| preempt_enable(); |
| } |
| |
| int get_tsc_mode(unsigned long adr) |
| { |
| unsigned int val; |
| |
| if (test_thread_flag(TIF_NOTSC)) |
| val = PR_TSC_SIGSEGV; |
| else |
| val = PR_TSC_ENABLE; |
| |
| return put_user(val, (unsigned int __user *)adr); |
| } |
| |
| int set_tsc_mode(unsigned int val) |
| { |
| if (val == PR_TSC_SIGSEGV) |
| disable_TSC(); |
| else if (val == PR_TSC_ENABLE) |
| enable_TSC(); |
| else |
| return -EINVAL; |
| |
| return 0; |
| } |
| |
| void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, |
| struct tss_struct *tss) |
| { |
| struct thread_struct *prev, *next; |
| |
| prev = &prev_p->thread; |
| next = &next_p->thread; |
| |
| if (test_tsk_thread_flag(prev_p, TIF_BLOCKSTEP) ^ |
| test_tsk_thread_flag(next_p, TIF_BLOCKSTEP)) { |
| unsigned long debugctl = get_debugctlmsr(); |
| |
| debugctl &= ~DEBUGCTLMSR_BTF; |
| if (test_tsk_thread_flag(next_p, TIF_BLOCKSTEP)) |
| debugctl |= DEBUGCTLMSR_BTF; |
| |
| update_debugctlmsr(debugctl); |
| } |
| |
| if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^ |
| test_tsk_thread_flag(next_p, TIF_NOTSC)) { |
| /* prev and next are different */ |
| if (test_tsk_thread_flag(next_p, TIF_NOTSC)) |
| hard_disable_TSC(); |
| else |
| hard_enable_TSC(); |
| } |
| |
| if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) { |
| /* |
| * Copy the relevant range of the IO bitmap. |
| * Normally this is 128 bytes or less: |
| */ |
| memcpy(tss->io_bitmap, next->io_bitmap_ptr, |
| max(prev->io_bitmap_max, next->io_bitmap_max)); |
| } else if (test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)) { |
| /* |
| * Clear any possible leftover bits: |
| */ |
| memset(tss->io_bitmap, 0xff, prev->io_bitmap_max); |
| } |
| propagate_user_return_notify(prev_p, next_p); |
| } |
| |
| /* |
| * Idle related variables and functions |
| */ |
| unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE; |
| EXPORT_SYMBOL(boot_option_idle_override); |
| |
| static void (*x86_idle)(void); |
| |
| #ifndef CONFIG_SMP |
| static inline void play_dead(void) |
| { |
| BUG(); |
| } |
| #endif |
| |
| #ifdef CONFIG_X86_64 |
| void enter_idle(void) |
| { |
| this_cpu_write(is_idle, 1); |
| idle_notifier_call_chain(IDLE_START); |
| } |
| |
| static void __exit_idle(void) |
| { |
| if (x86_test_and_clear_bit_percpu(0, is_idle) == 0) |
| return; |
| idle_notifier_call_chain(IDLE_END); |
| } |
| |
| /* Called from interrupts to signify idle end */ |
| void exit_idle(void) |
| { |
| /* idle loop has pid 0 */ |
| if (current->pid) |
| return; |
| __exit_idle(); |
| } |
| #endif |
| |
| void arch_cpu_idle_enter(void) |
| { |
| local_touch_nmi(); |
| enter_idle(); |
| } |
| |
| void arch_cpu_idle_exit(void) |
| { |
| __exit_idle(); |
| } |
| |
| void arch_cpu_idle_dead(void) |
| { |
| play_dead(); |
| } |
| |
| /* |
| * Called from the generic idle code. |
| */ |
| void arch_cpu_idle(void) |
| { |
| x86_idle(); |
| } |
| |
| /* |
| * We use this if we don't have any better idle routine.. |
| */ |
| void __cpuidle default_idle(void) |
| { |
| trace_cpu_idle_rcuidle(1, smp_processor_id()); |
| safe_halt(); |
| trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id()); |
| } |
| #ifdef CONFIG_APM_MODULE |
| EXPORT_SYMBOL(default_idle); |
| #endif |
| |
| #ifdef CONFIG_XEN |
| bool xen_set_default_idle(void) |
| { |
| bool ret = !!x86_idle; |
| |
| x86_idle = default_idle; |
| |
| return ret; |
| } |
| #endif |
| void stop_this_cpu(void *dummy) |
| { |
| local_irq_disable(); |
| /* |
| * Remove this CPU: |
| */ |
| set_cpu_online(smp_processor_id(), false); |
| disable_local_APIC(); |
| mcheck_cpu_clear(this_cpu_ptr(&cpu_info)); |
| |
| for (;;) |
| halt(); |
| } |
| |
| bool amd_e400_c1e_detected; |
| EXPORT_SYMBOL(amd_e400_c1e_detected); |
| |
| static cpumask_var_t amd_e400_c1e_mask; |
| |
| void amd_e400_remove_cpu(int cpu) |
| { |
| if (amd_e400_c1e_mask != NULL) |
| cpumask_clear_cpu(cpu, amd_e400_c1e_mask); |
| } |
| |
| /* |
| * AMD Erratum 400 aware idle routine. We check for C1E active in the interrupt |
| * pending message MSR. If we detect C1E, then we handle it the same |
| * way as C3 power states (local apic timer and TSC stop) |
| */ |
| static void amd_e400_idle(void) |
| { |
| if (!amd_e400_c1e_detected) { |
| u32 lo, hi; |
| |
| rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi); |
| |
| if (lo & K8_INTP_C1E_ACTIVE_MASK) { |
| amd_e400_c1e_detected = true; |
| if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC)) |
| mark_tsc_unstable("TSC halt in AMD C1E"); |
| pr_info("System has AMD C1E enabled\n"); |
| } |
| } |
| |
| if (amd_e400_c1e_detected) { |
| int cpu = smp_processor_id(); |
| |
| if (!cpumask_test_cpu(cpu, amd_e400_c1e_mask)) { |
| cpumask_set_cpu(cpu, amd_e400_c1e_mask); |
| /* Force broadcast so ACPI can not interfere. */ |
| tick_broadcast_force(); |
| pr_info("Switch to broadcast mode on CPU%d\n", cpu); |
| } |
| tick_broadcast_enter(); |
| |
| default_idle(); |
| |
| /* |
| * The switch back from broadcast mode needs to be |
| * called with interrupts disabled. |
| */ |
| local_irq_disable(); |
| tick_broadcast_exit(); |
| local_irq_enable(); |
| } else |
| default_idle(); |
| } |
| |
| /* |
| * Intel Core2 and older machines prefer MWAIT over HALT for C1. |
| * We can't rely on cpuidle installing MWAIT, because it will not load |
| * on systems that support only C1 -- so the boot default must be MWAIT. |
| * |
| * Some AMD machines are the opposite, they depend on using HALT. |
| * |
| * So for default C1, which is used during boot until cpuidle loads, |
| * use MWAIT-C1 on Intel HW that has it, else use HALT. |
| */ |
| static int prefer_mwait_c1_over_halt(const struct cpuinfo_x86 *c) |
| { |
| if (c->x86_vendor != X86_VENDOR_INTEL) |
| return 0; |
| |
| if (!cpu_has(c, X86_FEATURE_MWAIT) || static_cpu_has_bug(X86_BUG_MONITOR)) |
| return 0; |
| |
| return 1; |
| } |
| |
| /* |
| * MONITOR/MWAIT with no hints, used for default C1 state. This invokes MWAIT |
| * with interrupts enabled and no flags, which is backwards compatible with the |
| * original MWAIT implementation. |
| */ |
| static __cpuidle void mwait_idle(void) |
| { |
| if (!current_set_polling_and_test()) { |
| trace_cpu_idle_rcuidle(1, smp_processor_id()); |
| if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR)) { |
| mb(); /* quirk */ |
| clflush((void *)¤t_thread_info()->flags); |
| mb(); /* quirk */ |
| } |
| |
| __monitor((void *)¤t_thread_info()->flags, 0, 0); |
| if (!need_resched()) |
| __sti_mwait(0, 0); |
| else |
| local_irq_enable(); |
| trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id()); |
| } else { |
| local_irq_enable(); |
| } |
| __current_clr_polling(); |
| } |
| |
| void select_idle_routine(const struct cpuinfo_x86 *c) |
| { |
| #ifdef CONFIG_SMP |
| if (boot_option_idle_override == IDLE_POLL && smp_num_siblings > 1) |
| pr_warn_once("WARNING: polling idle and HT enabled, performance may degrade\n"); |
| #endif |
| if (x86_idle || boot_option_idle_override == IDLE_POLL) |
| return; |
| |
| if (boot_cpu_has_bug(X86_BUG_AMD_E400)) { |
| pr_info("using AMD E400 aware idle routine\n"); |
| x86_idle = amd_e400_idle; |
| } else if (prefer_mwait_c1_over_halt(c)) { |
| pr_info("using mwait in idle threads\n"); |
| x86_idle = mwait_idle; |
| } else |
| x86_idle = default_idle; |
| } |
| |
| void __init init_amd_e400_c1e_mask(void) |
| { |
| /* If we're using amd_e400_idle, we need to allocate amd_e400_c1e_mask. */ |
| if (x86_idle == amd_e400_idle) |
| zalloc_cpumask_var(&amd_e400_c1e_mask, GFP_KERNEL); |
| } |
| |
| static int __init idle_setup(char *str) |
| { |
| if (!str) |
| return -EINVAL; |
| |
| if (!strcmp(str, "poll")) { |
| pr_info("using polling idle threads\n"); |
| boot_option_idle_override = IDLE_POLL; |
| cpu_idle_poll_ctrl(true); |
| } else if (!strcmp(str, "halt")) { |
| /* |
| * When the boot option of idle=halt is added, halt is |
| * forced to be used for CPU idle. In such case CPU C2/C3 |
| * won't be used again. |
| * To continue to load the CPU idle driver, don't touch |
| * the boot_option_idle_override. |
| */ |
| x86_idle = default_idle; |
| boot_option_idle_override = IDLE_HALT; |
| } else if (!strcmp(str, "nomwait")) { |
| /* |
| * If the boot option of "idle=nomwait" is added, |
| * it means that mwait will be disabled for CPU C2/C3 |
| * states. In such case it won't touch the variable |
| * of boot_option_idle_override. |
| */ |
| boot_option_idle_override = IDLE_NOMWAIT; |
| } else |
| return -1; |
| |
| return 0; |
| } |
| early_param("idle", idle_setup); |
| |
| unsigned long arch_align_stack(unsigned long sp) |
| { |
| if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) |
| sp -= get_random_int() % 8192; |
| return sp & ~0xf; |
| } |
| |
| unsigned long arch_randomize_brk(struct mm_struct *mm) |
| { |
| return randomize_page(mm->brk, 0x02000000); |
| } |
| |
| /* |
| * Return saved PC of a blocked thread. |
| * What is this good for? it will be always the scheduler or ret_from_fork. |
| */ |
| unsigned long thread_saved_pc(struct task_struct *tsk) |
| { |
| struct inactive_task_frame *frame = |
| (struct inactive_task_frame *) READ_ONCE(tsk->thread.sp); |
| return READ_ONCE_NOCHECK(frame->ret_addr); |
| } |
| |
| /* |
| * Called from fs/proc with a reference on @p to find the function |
| * which called into schedule(). This needs to be done carefully |
| * because the task might wake up and we might look at a stack |
| * changing under us. |
| */ |
| unsigned long get_wchan(struct task_struct *p) |
| { |
| unsigned long start, bottom, top, sp, fp, ip, ret = 0; |
| int count = 0; |
| |
| if (!p || p == current || p->state == TASK_RUNNING) |
| return 0; |
| |
| if (!try_get_task_stack(p)) |
| return 0; |
| |
| start = (unsigned long)task_stack_page(p); |
| if (!start) |
| goto out; |
| |
| /* |
| * Layout of the stack page: |
| * |
| * ----------- topmax = start + THREAD_SIZE - sizeof(unsigned long) |
| * PADDING |
| * ----------- top = topmax - TOP_OF_KERNEL_STACK_PADDING |
| * stack |
| * ----------- bottom = start |
| * |
| * The tasks stack pointer points at the location where the |
| * framepointer is stored. The data on the stack is: |
| * ... IP FP ... IP FP |
| * |
| * We need to read FP and IP, so we need to adjust the upper |
| * bound by another unsigned long. |
| */ |
| top = start + THREAD_SIZE - TOP_OF_KERNEL_STACK_PADDING; |
| top -= 2 * sizeof(unsigned long); |
| bottom = start; |
| |
| sp = READ_ONCE(p->thread.sp); |
| if (sp < bottom || sp > top) |
| goto out; |
| |
| fp = READ_ONCE_NOCHECK(((struct inactive_task_frame *)sp)->bp); |
| do { |
| if (fp < bottom || fp > top) |
| goto out; |
| ip = READ_ONCE_NOCHECK(*(unsigned long *)(fp + sizeof(unsigned long))); |
| if (!in_sched_functions(ip)) { |
| ret = ip; |
| goto out; |
| } |
| fp = READ_ONCE_NOCHECK(*(unsigned long *)fp); |
| } while (count++ < 16 && p->state != TASK_RUNNING); |
| |
| out: |
| put_task_stack(p); |
| return ret; |
| } |