thread_info.h

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/* thread_info.h: low-level thread information
 *
 * Copyright (C) 2002  David Howells ([email protected])
 * - Incorporating suggestions made by Linus Torvalds and Dave Miller
 */

#ifndef _ASM_X86_THREAD_INFO_H
#define _ASM_X86_THREAD_INFO_H

#include <linux/compiler.h>
#include <asm/page.h>
#include <asm/types.h>

/*
 * low level task data that entry.S needs immediate access to
 * - this struct should fit entirely inside of one cache line
 * - this struct shares the supervisor stack pages
 */
#ifndef __ASSEMBLY__
struct task_struct;
struct exec_domain;
#include <asm/processor.h>
#include <asm/ftrace.h>
#include <linux/atomic.h>

struct thread_info {
    struct task_struct  *task;      /* main task structure */
    struct exec_domain  *exec_domain;   /* execution domain */
    __u32           flags;      /* low level flags */
    __u32           status;     /* thread synchronous flags */
    __u32           cpu;        /* current CPU */
    int         preempt_count;  /* 0 => preemptable,
                           <0 => BUG */
    mm_segment_t        addr_limit;
    struct restart_block    restart_block;
    void __user     *sysenter_return;
#ifdef CONFIG_X86_32
    unsigned long           previous_esp;   /* ESP of the previous stack in
                           case of nested (IRQ) stacks
                        */
    __u8            supervisor_stack[0];
#endif
    unsigned int        sig_on_uaccess_error:1;
    unsigned int        uaccess_err:1;  /* uaccess failed */
};

#define INIT_THREAD_INFO(tsk)           \
{                       \
    .task       = &tsk,         \
    .exec_domain    = &default_exec_domain, \
    .flags      = 0,            \
    .cpu        = 0,            \
    .preempt_count  = INIT_PREEMPT_COUNT,   \
    .addr_limit = KERNEL_DS,        \
    .restart_block = {          \
        .fn = do_no_restart_syscall,    \
    },                  \
}

#define init_thread_info    (init_thread_union.thread_info)
#define init_stack      (init_thread_union.stack)

#else /* !__ASSEMBLY__ */

#include <asm/asm-offsets.h>

#endif

/*
 * thread information flags
 * - these are process state flags that various assembly files
 *   may need to access
 * - pending work-to-be-done flags are in LSW
 * - other flags in MSW
 * Warning: layout of LSW is hardcoded in entry.S
 */
#define TIF_SYSCALL_TRACE   0   /* syscall trace active */
#define TIF_NOTIFY_RESUME   1   /* callback before returning to user */
#define TIF_SIGPENDING      2   /* signal pending */
#define TIF_NEED_RESCHED    3   /* rescheduling necessary */
#define TIF_SINGLESTEP      4   /* reenable singlestep on user return*/
#define TIF_SYSCALL_EMU     6   /* syscall emulation active */
#define TIF_SYSCALL_AUDIT   7   /* syscall auditing active */
#define TIF_SECCOMP     8   /* secure computing */
#define TIF_MCE_NOTIFY      10  /* notify userspace of an MCE */
#define TIF_USER_RETURN_NOTIFY  11  /* notify kernel of userspace return */
#define TIF_UPROBE      12  /* breakpointed or singlestepping */
#define TIF_NOTSC       16  /* TSC is not accessible in userland */
#define TIF_IA32        17  /* IA32 compatibility process */
#define TIF_FORK        18  /* ret_from_fork */
#define TIF_NOHZ        19  /* in adaptive nohz mode */
#define TIF_MEMDIE      20  /* is terminating due to OOM killer */
#define TIF_DEBUG       21  /* uses debug registers */
#define TIF_IO_BITMAP       22  /* uses I/O bitmap */
#define TIF_FORCED_TF       24  /* true if TF in eflags artificially */
#define TIF_BLOCKSTEP       25  /* set when we want DEBUGCTLMSR_BTF */
#define TIF_LAZY_MMU_UPDATES    27  /* task is updating the mmu lazily */
#define TIF_SYSCALL_TRACEPOINT  28  /* syscall tracepoint instrumentation */
#define TIF_ADDR32      29  /* 32-bit address space on 64 bits */
#define TIF_X32         30  /* 32-bit native x86-64 binary */

#define _TIF_SYSCALL_TRACE  (1 << TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME  (1 << TIF_NOTIFY_RESUME)
#define _TIF_SIGPENDING     (1 << TIF_SIGPENDING)
#define _TIF_SINGLESTEP     (1 << TIF_SINGLESTEP)
#define _TIF_NEED_RESCHED   (1 << TIF_NEED_RESCHED)
#define _TIF_SYSCALL_EMU    (1 << TIF_SYSCALL_EMU)
#define _TIF_SYSCALL_AUDIT  (1 << TIF_SYSCALL_AUDIT)
#define _TIF_SECCOMP        (1 << TIF_SECCOMP)
#define _TIF_MCE_NOTIFY     (1 << TIF_MCE_NOTIFY)
#define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
#define _TIF_UPROBE     (1 << TIF_UPROBE)
#define _TIF_NOTSC      (1 << TIF_NOTSC)
#define _TIF_IA32       (1 << TIF_IA32)
#define _TIF_FORK       (1 << TIF_FORK)
#define _TIF_NOHZ       (1 << TIF_NOHZ)
#define _TIF_DEBUG      (1 << TIF_DEBUG)
#define _TIF_IO_BITMAP      (1 << TIF_IO_BITMAP)
#define _TIF_FORCED_TF      (1 << TIF_FORCED_TF)
#define _TIF_BLOCKSTEP      (1 << TIF_BLOCKSTEP)
#define _TIF_LAZY_MMU_UPDATES   (1 << TIF_LAZY_MMU_UPDATES)
#define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
#define _TIF_ADDR32     (1 << TIF_ADDR32)
#define _TIF_X32        (1 << TIF_X32)

/* work to do in syscall_trace_enter() */
#define _TIF_WORK_SYSCALL_ENTRY \
    (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT |   \
     _TIF_SECCOMP | _TIF_SINGLESTEP | _TIF_SYSCALL_TRACEPOINT | \
     _TIF_NOHZ)

/* work to do in syscall_trace_leave() */
#define _TIF_WORK_SYSCALL_EXIT  \
    (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SINGLESTEP |    \
     _TIF_SYSCALL_TRACEPOINT | _TIF_NOHZ)

/* work to do on interrupt/exception return */
#define _TIF_WORK_MASK                          \
    (0x0000FFFF &                           \
     ~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|           \
       _TIF_SINGLESTEP|_TIF_SECCOMP|_TIF_SYSCALL_EMU))

/* work to do on any return to user space */
#define _TIF_ALLWORK_MASK                       \
    ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT |   \
    _TIF_NOHZ)

/* Only used for 64 bit */
#define _TIF_DO_NOTIFY_MASK                     \
    (_TIF_SIGPENDING | _TIF_MCE_NOTIFY | _TIF_NOTIFY_RESUME |   \
     _TIF_USER_RETURN_NOTIFY)

/* flags to check in __switch_to() */
#define _TIF_WORK_CTXSW                         \
    (_TIF_IO_BITMAP|_TIF_NOTSC|_TIF_BLOCKSTEP)

#define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY)
#define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW|_TIF_DEBUG)

#define PREEMPT_ACTIVE      0x10000000

#ifdef CONFIG_X86_32

#define STACK_WARN  (THREAD_SIZE/8)
/*
 * macros/functions for gaining access to the thread information structure
 *
 * preempt_count needs to be 1 initially, until the scheduler is functional.
 */
#ifndef __ASSEMBLY__


/* how to get the current stack pointer from C */
register unsigned long current_stack_pointer asm("esp") __used;

/* how to get the thread information struct from C */
static inline struct thread_info *current_thread_info(void)
{
    return (struct thread_info *)
        (current_stack_pointer & ~(THREAD_SIZE - 1));
}

#else /* !__ASSEMBLY__ */

/* how to get the thread information struct from ASM */
#define GET_THREAD_INFO(reg)     \
    movl $-THREAD_SIZE, reg; \
    andl %esp, reg

/* use this one if reg already contains %esp */
#define GET_THREAD_INFO_WITH_ESP(reg) \
    andl $-THREAD_SIZE, reg

#endif

#else /* X86_32 */

#include <asm/percpu.h>
#define KERNEL_STACK_OFFSET (5*8)

/*
 * macros/functions for gaining access to the thread information structure
 * preempt_count needs to be 1 initially, until the scheduler is functional.
 */
#ifndef __ASSEMBLY__
DECLARE_PER_CPU(unsigned long, kernel_stack);

static inline struct thread_info *current_thread_info(void)
{
    struct thread_info *ti;
    ti = (void *)(this_cpu_read_stable(kernel_stack) +
              KERNEL_STACK_OFFSET - THREAD_SIZE);
    return ti;
}

#else /* !__ASSEMBLY__ */

/* how to get the thread information struct from ASM */
#define GET_THREAD_INFO(reg) \
    movq PER_CPU_VAR(kernel_stack),reg ; \
    subq $(THREAD_SIZE-KERNEL_STACK_OFFSET),reg

/*
 * Same if PER_CPU_VAR(kernel_stack) is, perhaps with some offset, already in
 * a certain register (to be used in assembler memory operands).
 */
#define THREAD_INFO(reg, off) KERNEL_STACK_OFFSET+(off)-THREAD_SIZE(reg)

#endif

#endif /* !X86_32 */

/*
 * Thread-synchronous status.
 *
 * This is different from the flags in that nobody else
 * ever touches our thread-synchronous status, so we don't
 * have to worry about atomic accesses.
 */
#define TS_COMPAT       0x0002  /* 32bit syscall active (64BIT)*/
#define TS_POLLING      0x0004  /* idle task polling need_resched,
                       skip sending interrupt */
#define TS_RESTORE_SIGMASK  0x0008  /* restore signal mask in do_signal() */

#define tsk_is_polling(t) (task_thread_info(t)->status & TS_POLLING)

#ifndef __ASSEMBLY__
#define HAVE_SET_RESTORE_SIGMASK    1
static inline void set_restore_sigmask(void)
{
    struct thread_info *ti = current_thread_info();
    ti->status |= TS_RESTORE_SIGMASK;
    WARN_ON(!test_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags));
}
static inline void clear_restore_sigmask(void)
{
    current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
}
static inline bool test_restore_sigmask(void)
{
    return current_thread_info()->status & TS_RESTORE_SIGMASK;
}
static inline bool test_and_clear_restore_sigmask(void)
{
    struct thread_info *ti = current_thread_info();
    if (!(ti->status & TS_RESTORE_SIGMASK))
        return false;
    ti->status &= ~TS_RESTORE_SIGMASK;
    return true;
}

static inline bool is_ia32_task(void)
{
#ifdef CONFIG_X86_32
    return true;
#endif
#ifdef CONFIG_IA32_EMULATION
    if (current_thread_info()->status & TS_COMPAT)
        return true;
#endif
    return false;
}
#endif  /* !__ASSEMBLY__ */

#ifndef __ASSEMBLY__
extern void arch_task_cache_init(void);
extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
extern void arch_release_task_struct(struct task_struct *tsk);
#endif
#endif /* _ASM_X86_THREAD_INFO_H */