alistair23-linux/include/asm-x86_64/thread_info.h

/* thread_info.h: x86_64 low-level thread information
 *
 * Copyright (C) 2002  David Howells (dhowells@redhat.com)
 * - Incorporating suggestions made by Linus Torvalds and Dave Miller
 */

#ifndef _ASM_THREAD_INFO_H
#define _ASM_THREAD_INFO_H

#ifdef __KERNEL__

#include <asm/page.h>
#include <asm/types.h>
#include <asm/pda.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/mmsegment.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;
};
#endif

/*
 * macros/functions for gaining access to the thread information structure
 * preempt_count needs to be 1 initially, until the scheduler is functional.
 */
#ifndef __ASSEMBLY__
#define INIT_THREAD_INFO(tsk)			\
{						\
	.task	       = &tsk,			\
	.exec_domain   = &default_exec_domain,	\
	.flags	       = 0,			\
	.cpu	       = 0,			\
	.preempt_count = 1,			\
	.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)

static inline struct thread_info *current_thread_info(void)
{ 
	struct thread_info *ti;
	ti = (void *)(read_pda(kernelstack) + PDA_STACKOFFSET - THREAD_SIZE);
	return ti; 
}

/* do not use in interrupt context */
static inline struct thread_info *stack_thread_info(void)
{
	struct thread_info *ti;
	__asm__("andq %%rsp,%0; ":"=r" (ti) : "0" (~(THREAD_SIZE - 1)));
	return ti;
}

/* thread information allocation */
#ifdef CONFIG_DEBUG_STACK_USAGE
#define alloc_thread_info(tsk)					\
    ({								\
	struct thread_info *ret;				\
								\
	ret = ((struct thread_info *) __get_free_pages(GFP_KERNEL,THREAD_ORDER)); \
	if (ret)						\
		memset(ret, 0, THREAD_SIZE);			\
	ret;							\
    })
#else
#define alloc_thread_info(tsk) \
	((struct thread_info *) __get_free_pages(GFP_KERNEL,THREAD_ORDER))
#endif

#define free_thread_info(ti) free_pages((unsigned long) (ti), THREAD_ORDER)

#else /* !__ASSEMBLY__ */

/* how to get the thread information struct from ASM */
#define GET_THREAD_INFO(reg) \
	movq %gs:pda_kernelstack,reg ; \
	subq $(THREAD_SIZE-PDA_STACKOFFSET),reg

#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	/* resumption notification requested */
#define TIF_SIGPENDING		2	/* signal pending */
#define TIF_NEED_RESCHED	3	/* rescheduling necessary */
#define TIF_SINGLESTEP		4	/* reenable singlestep on user return*/
#define TIF_IRET		5	/* force IRET */
#define TIF_SYSCALL_AUDIT	7	/* syscall auditing active */
#define TIF_SECCOMP		8	/* secure computing */
#define TIF_RESTORE_SIGMASK	9	/* restore signal mask in do_signal */
/* 16 free */
#define TIF_IA32		17	/* 32bit process */ 
#define TIF_FORK		18	/* ret_from_fork */
#define TIF_ABI_PENDING		19
#define TIF_MEMDIE		20
#define TIF_DEBUG		21	/* uses debug registers */
#define TIF_IO_BITMAP		22	/* uses I/O bitmap */
#define TIF_FREEZE		23	/* is freezing for suspend */

#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_IRET		(1<<TIF_IRET)
#define _TIF_SYSCALL_AUDIT	(1<<TIF_SYSCALL_AUDIT)
#define _TIF_SECCOMP		(1<<TIF_SECCOMP)
#define _TIF_RESTORE_SIGMASK	(1<<TIF_RESTORE_SIGMASK)
#define _TIF_IA32		(1<<TIF_IA32)
#define _TIF_FORK		(1<<TIF_FORK)
#define _TIF_ABI_PENDING	(1<<TIF_ABI_PENDING)
#define _TIF_DEBUG		(1<<TIF_DEBUG)
#define _TIF_IO_BITMAP		(1<<TIF_IO_BITMAP)
#define _TIF_FREEZE		(1<<TIF_FREEZE)

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

/* flags to check in __switch_to() */
#define _TIF_WORK_CTXSW (_TIF_DEBUG|_TIF_IO_BITMAP)

#define PREEMPT_ACTIVE     0x10000000

/*
 * 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_USEDFPU		0x0001	/* FPU was used by this task this quantum (SMP) */
#define TS_COMPAT		0x0002	/* 32bit syscall active */
#define TS_POLLING		0x0004	/* true if in idle loop and not sleeping */

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

#endif /* __KERNEL__ */

#endif /* _ASM_THREAD_INFO_H */