[safe/jmp/linux-2.6] / arch / x86 / kernel / process.c

#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/module.h>
#include <linux/pm.h>
#include <linux/clockchips.h>
#include <linux/random.h>
#include <trace/events/power.h>
#include <asm/system.h>
#include <asm/apic.h>
#include <asm/syscalls.h>
#include <asm/idle.h>
#include <asm/uaccess.h>
#include <asm/i387.h>
#include <asm/ds.h>
#include <asm/debugreg.h>
#include <asm/hw_breakpoint.h>

unsigned long idle_halt;
EXPORT_SYMBOL(idle_halt);
unsigned long idle_nomwait;
EXPORT_SYMBOL(idle_nomwait);

struct kmem_cache *task_xstate_cachep;

int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
        *dst = *src;
        if (src->thread.xstate) {
                dst->thread.xstate = kmem_cache_alloc(task_xstate_cachep,
                                                      GFP_KERNEL);
                if (!dst->thread.xstate)
                        return -ENOMEM;
                WARN_ON((unsigned long)dst->thread.xstate & 15);
                memcpy(dst->thread.xstate, src->thread.xstate, xstate_size);
        }
        return 0;
}

void free_thread_xstate(struct task_struct *tsk)
{
        if (tsk->thread.xstate) {
                kmem_cache_free(task_xstate_cachep, tsk->thread.xstate);
                tsk->thread.xstate = NULL;
        }
        if (unlikely(test_tsk_thread_flag(tsk, TIF_DEBUG)))
                flush_thread_hw_breakpoint(tsk);

        WARN(tsk->thread.ds_ctx, "leaking DS context\n");
}

void free_thread_info(struct thread_info *ti)
{
        free_thread_xstate(ti->task);
        free_pages((unsigned long)ti, get_order(THREAD_SIZE));
}

void arch_task_cache_init(void)
{
        task_xstate_cachep =
                kmem_cache_create("task_xstate", xstate_size,
                                  __alignof__(union thread_xstate),
                                  SLAB_PANIC | SLAB_NOTRACK, NULL);
}

/*
 * Free current thread data structures etc..
 */
void exit_thread(void)
{
        struct task_struct *me = current;
        struct thread_struct *t = &me->thread;
        unsigned long *bp = t->io_bitmap_ptr;

        if (bp) {
                struct tss_struct *tss = &per_cpu(init_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);
        }
}

void flush_thread(void)
{
        struct task_struct *tsk = current;

#ifdef CONFIG_X86_64
        if (test_tsk_thread_flag(tsk, TIF_ABI_PENDING)) {
                clear_tsk_thread_flag(tsk, TIF_ABI_PENDING);
                if (test_tsk_thread_flag(tsk, TIF_IA32)) {
                        clear_tsk_thread_flag(tsk, TIF_IA32);
                } else {
                        set_tsk_thread_flag(tsk, TIF_IA32);
                        current_thread_info()->status |= TS_COMPAT;
                }
        }
#endif

        if (unlikely(test_tsk_thread_flag(tsk, TIF_DEBUG)))
                flush_thread_hw_breakpoint(tsk);
        memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
        /*
         * Forget coprocessor state..
         */
        tsk->fpu_counter = 0;
        clear_fpu(tsk);
        clear_used_math();
}

static void hard_disable_TSC(void)
{
        write_cr4(read_cr4() | 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)
{
        write_cr4(read_cr4() & ~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(next_p, TIF_DS_AREA_MSR) ||
            test_tsk_thread_flag(prev_p, TIF_DS_AREA_MSR))
                ds_switch_to(prev_p, next_p);
        else if (next->debugctlmsr != prev->debugctlmsr)
                update_debugctlmsr(next->debugctlmsr);

        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);
        }
}

int sys_fork(struct pt_regs *regs)
{
        return do_fork(SIGCHLD, regs->sp, regs, 0, NULL, NULL);
}

/*
 * This is trivial, and on the face of it looks like it
 * could equally well be done in user mode.
 *
 * Not so, for quite unobvious reasons - register pressure.
 * In user mode vfork() cannot have a stack frame, and if
 * done by calling the "clone()" system call directly, you
 * do not have enough call-clobbered registers to hold all
 * the information you need.
 */
int sys_vfork(struct pt_regs *regs)
{
        return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->sp, regs, 0,
                       NULL, NULL);
}


/*
 * Idle related variables and functions
 */
unsigned long boot_option_idle_override = 0;
EXPORT_SYMBOL(boot_option_idle_override);

/*
 * Powermanagement idle function, if any..
 */
void (*pm_idle)(void);
EXPORT_SYMBOL(pm_idle);

#ifdef CONFIG_X86_32
/*
 * This halt magic was a workaround for ancient floppy DMA
 * wreckage. It should be safe to remove.
 */
static int hlt_counter;
void disable_hlt(void)
{
        hlt_counter++;
}
EXPORT_SYMBOL(disable_hlt);

void enable_hlt(void)
{
        hlt_counter--;
}
EXPORT_SYMBOL(enable_hlt);

static inline int hlt_use_halt(void)
{
        return (!hlt_counter && boot_cpu_data.hlt_works_ok);
}
#else
static inline int hlt_use_halt(void)
{
        return 1;
}
#endif

/*
 * We use this if we don't have any better
 * idle routine..
 */
void default_idle(void)
{
        if (hlt_use_halt()) {
                trace_power_start(POWER_CSTATE, 1);
                current_thread_info()->status &= ~TS_POLLING;
                /*
                 * TS_POLLING-cleared state must be visible before we
                 * test NEED_RESCHED:
                 */
                smp_mb();

                if (!need_resched())
                        safe_halt();    /* enables interrupts racelessly */
                else
                        local_irq_enable();
                current_thread_info()->status |= TS_POLLING;
        } else {
                local_irq_enable();
                /* loop is done by the caller */
                cpu_relax();
        }
}
#ifdef CONFIG_APM_MODULE
EXPORT_SYMBOL(default_idle);
#endif

void stop_this_cpu(void *dummy)
{
        local_irq_disable();
        /*
         * Remove this CPU:
         */
        set_cpu_online(smp_processor_id(), false);
        disable_local_APIC();

        for (;;) {
                if (hlt_works(smp_processor_id()))
                        halt();
        }
}

static void do_nothing(void *unused)
{
}

/*
 * cpu_idle_wait - Used to ensure that all the CPUs discard old value of
 * pm_idle and update to new pm_idle value. Required while changing pm_idle
 * handler on SMP systems.
 *
 * Caller must have changed pm_idle to the new value before the call. Old
 * pm_idle value will not be used by any CPU after the return of this function.
 */
void cpu_idle_wait(void)
{
        smp_mb();
        /* kick all the CPUs so that they exit out of pm_idle */
        smp_call_function(do_nothing, NULL, 1);
}
EXPORT_SYMBOL_GPL(cpu_idle_wait);

/*
 * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
 * which can obviate IPI to trigger checking of need_resched.
 * We execute MONITOR against need_resched and enter optimized wait state
 * through MWAIT. Whenever someone changes need_resched, we would be woken
 * up from MWAIT (without an IPI).
 *
 * New with Core Duo processors, MWAIT can take some hints based on CPU
 * capability.
 */
void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
{
        trace_power_start(POWER_CSTATE, (ax>>4)+1);
        if (!need_resched()) {
                if (cpu_has(&current_cpu_data, X86_FEATURE_CLFLUSH_MONITOR))
                        clflush((void *)&current_thread_info()->flags);

                __monitor((void *)&current_thread_info()->flags, 0, 0);
                smp_mb();
                if (!need_resched())
                        __mwait(ax, cx);
        }
}

/* Default MONITOR/MWAIT with no hints, used for default C1 state */
static void mwait_idle(void)
{
        if (!need_resched()) {
                trace_power_start(POWER_CSTATE, 1);
                if (cpu_has(&current_cpu_data, X86_FEATURE_CLFLUSH_MONITOR))
                        clflush((void *)&current_thread_info()->flags);

                __monitor((void *)&current_thread_info()->flags, 0, 0);
                smp_mb();
                if (!need_resched())
                        __sti_mwait(0, 0);
                else
                        local_irq_enable();
        } else
                local_irq_enable();
}

/*
 * On SMP it's slightly faster (but much more power-consuming!)
 * to poll the ->work.need_resched flag instead of waiting for the
 * cross-CPU IPI to arrive. Use this option with caution.
 */
static void poll_idle(void)
{
        trace_power_start(POWER_CSTATE, 0);
        local_irq_enable();
        while (!need_resched())
                cpu_relax();
        trace_power_end(0);
}

/*
 * mwait selection logic:
 *
 * It depends on the CPU. For AMD CPUs that support MWAIT this is
 * wrong. Family 0x10 and 0x11 CPUs will enter C1 on HLT. Powersavings
 * then depend on a clock divisor and current Pstate of the core. If
 * all cores of a processor are in halt state (C1) the processor can
 * enter the C1E (C1 enhanced) state. If mwait is used this will never
 * happen.
 *
 * idle=mwait overrides this decision and forces the usage of mwait.
 */
static int __cpuinitdata force_mwait;

#define MWAIT_INFO                      0x05
#define MWAIT_ECX_EXTENDED_INFO         0x01
#define MWAIT_EDX_C1                    0xf0

static int __cpuinit mwait_usable(const struct cpuinfo_x86 *c)
{
        u32 eax, ebx, ecx, edx;

        if (force_mwait)
                return 1;

        if (c->cpuid_level < MWAIT_INFO)
                return 0;

        cpuid(MWAIT_INFO, &eax, &ebx, &ecx, &edx);
        /* Check, whether EDX has extended info about MWAIT */
        if (!(ecx & MWAIT_ECX_EXTENDED_INFO))
                return 1;

        /*
         * edx enumeratios MONITOR/MWAIT extensions. Check, whether
         * C1  supports MWAIT
         */
        return (edx & MWAIT_EDX_C1);
}

/*
 * Check for AMD CPUs, which have potentially C1E support
 */
static int __cpuinit check_c1e_idle(const struct cpuinfo_x86 *c)
{
        if (c->x86_vendor != X86_VENDOR_AMD)
                return 0;

        if (c->x86 < 0x0F)
                return 0;

        /* Family 0x0f models < rev F do not have C1E */
        if (c->x86 == 0x0f && c->x86_model < 0x40)
                return 0;

        return 1;
}

static cpumask_var_t c1e_mask;
static int c1e_detected;

void c1e_remove_cpu(int cpu)
{
        if (c1e_mask != NULL)
                cpumask_clear_cpu(cpu, c1e_mask);
}

/*
 * C1E 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 c1e_idle(void)
{
        if (need_resched())
                return;

        if (!c1e_detected) {
                u32 lo, hi;

                rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
                if (lo & K8_INTP_C1E_ACTIVE_MASK) {
                        c1e_detected = 1;
                        if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
                                mark_tsc_unstable("TSC halt in AMD C1E");
                        printk(KERN_INFO "System has AMD C1E enabled\n");
                        set_cpu_cap(&boot_cpu_data, X86_FEATURE_AMDC1E);
                }
        }

        if (c1e_detected) {
                int cpu = smp_processor_id();

                if (!cpumask_test_cpu(cpu, c1e_mask)) {
                        cpumask_set_cpu(cpu, c1e_mask);
                        /*
                         * Force broadcast so ACPI can not interfere.
                         */
                        clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_FORCE,
                                           &cpu);
                        printk(KERN_INFO "Switch to broadcast mode on CPU%d\n",
                               cpu);
                }
                clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);

                default_idle();

                /*
                 * The switch back from broadcast mode needs to be
                 * called with interrupts disabled.
                 */
                 local_irq_disable();
                 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
                 local_irq_enable();
        } else
                default_idle();
}

void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
{
#ifdef CONFIG_SMP
        if (pm_idle == poll_idle && smp_num_siblings > 1) {
                printk(KERN_WARNING "WARNING: polling idle and HT enabled,"
                        " performance may degrade.\n");
        }
#endif
        if (pm_idle)
                return;

        if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {
                /*
                 * One CPU supports mwait => All CPUs supports mwait
                 */
                printk(KERN_INFO "using mwait in idle threads.\n");
                pm_idle = mwait_idle;
        } else if (check_c1e_idle(c)) {
                printk(KERN_INFO "using C1E aware idle routine\n");
                pm_idle = c1e_idle;
        } else
                pm_idle = default_idle;
}

void __init init_c1e_mask(void)
{
        /* If we're using c1e_idle, we need to allocate c1e_mask. */
        if (pm_idle == c1e_idle)
                zalloc_cpumask_var(&c1e_mask, GFP_KERNEL);
}

static int __init idle_setup(char *str)
{
        if (!str)
                return -EINVAL;

        if (!strcmp(str, "poll")) {
                printk("using polling idle threads.\n");
                pm_idle = poll_idle;
        } else if (!strcmp(str, "mwait"))
                force_mwait = 1;
        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.
                 */
                pm_idle = default_idle;
                idle_halt = 1;
                return 0;
        } 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.
                 */
                idle_nomwait = 1;
                return 0;
        } else
                return -1;

        boot_option_idle_override = 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)
{
        unsigned long range_end = mm->brk + 0x02000000;
        return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
}