[deliverable/linux.git] / arch / x86 / include / asm / thread_info.h

/* thread_info.h: low-level thread information
 *
 * Copyright (C) 2002  David Howells (dhowells@redhat.com)
 * - 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/percpu.h>
#include <asm/types.h>

/*
 * TOP_OF_KERNEL_STACK_PADDING is a number of unused bytes that we
 * reserve at the top of the kernel stack.  We do it because of a nasty
 * 32-bit corner case.  On x86_32, the hardware stack frame is
 * variable-length.  Except for vm86 mode, struct pt_regs assumes a
 * maximum-length frame.  If we enter from CPL 0, the top 8 bytes of
 * pt_regs don't actually exist.  Ordinarily this doesn't matter, but it
 * does in at least one case:
 *
 * If we take an NMI early enough in SYSENTER, then we can end up with
 * pt_regs that extends above sp0.  On the way out, in the espfix code,
 * we can read the saved SS value, but that value will be above sp0.
 * Without this offset, that can result in a page fault.  (We are
 * careful that, in this case, the value we read doesn't matter.)
 *
 * In vm86 mode, the hardware frame is much longer still, so add 16
 * bytes to make room for the real-mode segments.
 *
 * x86_64 has a fixed-length stack frame.
 */
#ifdef CONFIG_X86_32
# ifdef CONFIG_VM86
#  define TOP_OF_KERNEL_STACK_PADDING 16
# else
#  define TOP_OF_KERNEL_STACK_PADDING 8
# endif
#else
# define TOP_OF_KERNEL_STACK_PADDING 0
#endif

/*
 * 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;
#include <asm/cpufeature.h>
#include <linux/atomic.h>

struct thread_info {
	struct task_struct	*task;		/* main task structure */
	__u32			flags;		/* low level flags */
	__u32			status;		/* thread synchronous flags */
	__u32			cpu;		/* current CPU */
};

#define INIT_THREAD_INFO(tsk)			\
{						\
	.task		= &tsk,			\
	.flags		= 0,			\
	.cpu		= 0,			\
}

#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_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_POLLING_NRFLAG	21	/* idle is polling for TIF_NEED_RESCHED */
#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_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_POLLING_NRFLAG	(1 << TIF_POLLING_NRFLAG)
#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().  Also includes TIF_NOHZ for
 * enter_from_user_mode()
 */
#define _TIF_WORK_SYSCALL_ENTRY	\
	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT |	\
	 _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT |	\
	 _TIF_NOHZ)

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

/* 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)

#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__

static inline struct thread_info *current_thread_info(void)
{
	return (struct thread_info *)(current_top_of_stack() - THREAD_SIZE);
}

static inline unsigned long current_stack_pointer(void)
{
	unsigned long sp;
#ifdef CONFIG_X86_64
	asm("mov %%rsp,%0" : "=g" (sp));
#else
	asm("mov %%esp,%0" : "=g" (sp));
#endif
	return sp;
}

/*
 * Walks up the stack frames to make sure that the specified object is
 * entirely contained by a single stack frame.
 *
 * Returns:
 *		 1 if within a frame
 *		-1 if placed across a frame boundary (or outside stack)
 *		 0 unable to determine (no frame pointers, etc)
 */
static inline int arch_within_stack_frames(const void * const stack,
					   const void * const stackend,
					   const void *obj, unsigned long len)
{
#if defined(CONFIG_FRAME_POINTER)
	const void *frame = NULL;
	const void *oldframe;

	oldframe = __builtin_frame_address(1);
	if (oldframe)
		frame = __builtin_frame_address(2);
	/*
	 * low ----------------------------------------------> high
	 * [saved bp][saved ip][args][local vars][saved bp][saved ip]
	 *                     ^----------------^
	 *               allow copies only within here
	 */
	while (stack <= frame && frame < stackend) {
		/*
		 * If obj + len extends past the last frame, this
		 * check won't pass and the next frame will be 0,
		 * causing us to bail out and correctly report
		 * the copy as invalid.
		 */
		if (obj + len <= frame)
			return obj >= oldframe + 2 * sizeof(void *) ? 1 : -1;
		oldframe = frame;
		frame = *(const void * const *)frame;
	}
	return -1;
#else
	return 0;
#endif
}

#else /* !__ASSEMBLY__ */

#ifdef CONFIG_X86_64
# define cpu_current_top_of_stack (cpu_tss + TSS_sp0)
#endif

/*
 * ASM operand which evaluates to a 'thread_info' address of
 * the current task, if it is known that "reg" is exactly "off"
 * bytes below the top of the stack currently.
 *
 * ( The kernel stack's size is known at build time, it is usually
 *   2 or 4 pages, and the bottom  of the kernel stack contains
 *   the thread_info structure. So to access the thread_info very
 *   quickly from assembly code we can calculate down from the
 *   top of the kernel stack to the bottom, using constant,
 *   build-time calculations only. )
 *
 * For example, to fetch the current thread_info->flags value into %eax
 * on x86-64 defconfig kernels, in syscall entry code where RSP is
 * currently at exactly SIZEOF_PTREGS bytes away from the top of the
 * stack:
 *
 *      mov ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS), %eax
 *
 * will translate to:
 *
 *      8b 84 24 b8 c0 ff ff      mov    -0x3f48(%rsp), %eax
 *
 * which is below the current RSP by almost 16K.
 */
#define ASM_THREAD_INFO(field, reg, off) ((field)+(off)-THREAD_SIZE)(reg)

#endif

/*
 * 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)*/
#ifdef CONFIG_COMPAT
#define TS_I386_REGS_POKED	0x0004	/* regs poked by 32-bit ptracer */
#endif

#ifndef __ASSEMBLY__

static inline bool in_ia32_syscall(void)
{
#ifdef CONFIG_X86_32
	return true;
#endif
#ifdef CONFIG_IA32_EMULATION
	if (current_thread_info()->status & TS_COMPAT)
		return true;
#endif
	return false;
}

/*
 * Force syscall return via IRET by making it look as if there was
 * some work pending. IRET is our most capable (but slowest) syscall
 * return path, which is able to restore modified SS, CS and certain
 * EFLAGS values that other (fast) syscall return instructions
 * are not able to restore properly.
 */
#define force_iret() set_thread_flag(TIF_NOTIFY_RESUME)

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	/* !__ASSEMBLY__ */

#endif /* _ASM_X86_THREAD_INFO_H */
Commit	Line	Data
2052e8d4 CL	1	/* thread_info.h: low-level thread information
	2	*
	3	* Copyright (C) 2002 David Howells (dhowells@redhat.com)
	4	* - Incorporating suggestions made by Linus Torvalds and Dave Miller
	5	*/
	6
1965aae3 PA	7	#ifndef _ASM_X86_THREAD_INFO_H
1965aae3 PA	8	#define _ASM_X86_THREAD_INFO_H
2052e8d4	9
2052e8d4 CL	10	#include <linux/compiler.h>
2052e8d4 CL	11	#include <asm/page.h>
198d208d	12	#include <asm/percpu.h>
12a638e1 CL	13	#include <asm/types.h>
12a638e1 CL	14
3ee4298f AL	15	/*
	16	* TOP_OF_KERNEL_STACK_PADDING is a number of unused bytes that we
	17	* reserve at the top of the kernel stack. We do it because of a nasty
	18	* 32-bit corner case. On x86_32, the hardware stack frame is
	19	* variable-length. Except for vm86 mode, struct pt_regs assumes a
	20	* maximum-length frame. If we enter from CPL 0, the top 8 bytes of
	21	* pt_regs don't actually exist. Ordinarily this doesn't matter, but it
	22	* does in at least one case:
	23	*
	24	* If we take an NMI early enough in SYSENTER, then we can end up with
	25	* pt_regs that extends above sp0. On the way out, in the espfix code,
	26	* we can read the saved SS value, but that value will be above sp0.
	27	* Without this offset, that can result in a page fault. (We are
	28	* careful that, in this case, the value we read doesn't matter.)
	29	*
5ed92a8a BG	30	* In vm86 mode, the hardware frame is much longer still, so add 16
5ed92a8a BG	31	* bytes to make room for the real-mode segments.
3ee4298f AL	32	*
	33	* x86_64 has a fixed-length stack frame.
	34	*/
	35	#ifdef CONFIG_X86_32
5ed92a8a BG	36	# ifdef CONFIG_VM86
	37	# define TOP_OF_KERNEL_STACK_PADDING 16
	38	# else
	39	# define TOP_OF_KERNEL_STACK_PADDING 8
	40	# endif
3ee4298f AL	41	#else
	42	# define TOP_OF_KERNEL_STACK_PADDING 0
	43	#endif
	44
2052e8d4 CL	45	/*
	46	* low level task data that entry.S needs immediate access to
	47	* - this struct should fit entirely inside of one cache line
	48	* - this struct shares the supervisor stack pages
2052e8d4 CL	49	*/
2052e8d4 CL	50	#ifndef __ASSEMBLY__
006c484b	51	struct task_struct;
cd4d09ec	52	#include <asm/cpufeature.h>
60063497	53	#include <linux/atomic.h>
2052e8d4 CL	54
	55	struct thread_info {
	56	struct task_struct task; / main task structure */
affa219b	57	__u32 flags; /* low level flags */
006c484b	58	__u32 status; /* thread synchronous flags */
2052e8d4	59	__u32 cpu; /* current CPU */
2052e8d4	60	};
3351cc03 CL	61
	62	#define INIT_THREAD_INFO(tsk) \
	63	{ \
	64	.task = &tsk, \
3351cc03 CL	65	.flags = 0, \
3351cc03 CL	66	.cpu = 0, \
3351cc03 CL	67	}
	68
	69	#define init_thread_info (init_thread_union.thread_info)
	70	#define init_stack (init_thread_union.stack)
	71
2052e8d4 CL	72	#else /* !__ASSEMBLY__ */
	73
	74	#include <asm/asm-offsets.h>
	75
	76	#endif
	77
e57549b0 CL	78	/*
	79	* thread information flags
	80	* - these are process state flags that various assembly files
	81	* may need to access
	82	* - pending work-to-be-done flags are in LSW
	83	* - other flags in MSW
	84	* Warning: layout of LSW is hardcoded in entry.S
	85	*/
	86	#define TIF_SYSCALL_TRACE 0 /* syscall trace active */
59e52130	87	#define TIF_NOTIFY_RESUME 1 /* callback before returning to user */
e57549b0 CL	88	#define TIF_SIGPENDING 2 /* signal pending */
	89	#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
	90	#define TIF_SINGLESTEP 4 /* reenable singlestep on user return*/
e57549b0	91	#define TIF_SYSCALL_EMU 6 /* syscall emulation active */
e57549b0 CL	92	#define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
e57549b0 CL	93	#define TIF_SECCOMP 8 /* secure computing */
7c68af6e	94	#define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */
0326f5a9	95	#define TIF_UPROBE 12 /* breakpointed or singlestepping */
e57549b0	96	#define TIF_NOTSC 16 /* TSC is not accessible in userland */
6bd33008	97	#define TIF_IA32 17 /* IA32 compatibility process */
e57549b0	98	#define TIF_FORK 18 /* ret_from_fork */
bf5a3c13	99	#define TIF_NOHZ 19 /* in adaptive nohz mode */
0ddc9324	100	#define TIF_MEMDIE 20 /* is terminating due to OOM killer */
f80c5b39	101	#define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */
e57549b0	102	#define TIF_IO_BITMAP 22 /* uses I/O bitmap */
e57549b0	103	#define TIF_FORCED_TF 24 /* true if TF in eflags artificially */
ea8e61b7	104	#define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */
b407fc57	105	#define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */
66700001	106	#define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */
6bd33008	107	#define TIF_ADDR32 29 /* 32-bit address space on 64 bits */
bb212724	108	#define TIF_X32 30 /* 32-bit native x86-64 binary */
e57549b0 CL	109
e57549b0 CL	110	#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
59e52130	111	#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
e57549b0 CL	112	#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
	113	#define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
	114	#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
e57549b0	115	#define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU)
e57549b0 CL	116	#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
e57549b0 CL	117	#define _TIF_SECCOMP (1 << TIF_SECCOMP)
7c68af6e	118	#define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
0326f5a9	119	#define _TIF_UPROBE (1 << TIF_UPROBE)
e57549b0 CL	120	#define _TIF_NOTSC (1 << TIF_NOTSC)
	121	#define _TIF_IA32 (1 << TIF_IA32)
	122	#define _TIF_FORK (1 << TIF_FORK)
bf5a3c13	123	#define _TIF_NOHZ (1 << TIF_NOHZ)
f80c5b39	124	#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
e57549b0	125	#define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
e57549b0	126	#define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
ea8e61b7	127	#define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP)
b407fc57	128	#define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES)
66700001	129	#define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
6bd33008	130	#define _TIF_ADDR32 (1 << TIF_ADDR32)
bb212724	131	#define _TIF_X32 (1 << TIF_X32)
e57549b0	132
9999c8c0 AL	133	/*
	134	* work to do in syscall_trace_enter(). Also includes TIF_NOHZ for
	135	* enter_from_user_mode()
	136	*/
d4d67150	137	#define _TIF_WORK_SYSCALL_ENTRY \
66700001	138	(_TIF_SYSCALL_TRACE \| _TIF_SYSCALL_EMU \| _TIF_SYSCALL_AUDIT \| \
392a6254	139	_TIF_SECCOMP \| _TIF_SYSCALL_TRACEPOINT \| \
bf5a3c13	140	_TIF_NOHZ)
d4d67150	141
00c1bb13	142	/* work to do on any return to user space */
66700001	143	#define _TIF_ALLWORK_MASK \
bf5a3c13 FW	144	((0x0000FFFF & ~_TIF_SECCOMP) \| _TIF_SYSCALL_TRACEPOINT \| \
bf5a3c13 FW	145	_TIF_NOHZ)
00c1bb13	146
00c1bb13 CL	147	/* flags to check in __switch_to() */
00c1bb13 CL	148	#define _TIF_WORK_CTXSW \
ea8e61b7	149	(_TIF_IO_BITMAP\|_TIF_NOTSC\|_TIF_BLOCKSTEP)
00c1bb13	150
7c68af6e	151	#define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW\|_TIF_USER_RETURN_NOTIFY)
37f07655	152	#define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)
00c1bb13	153
198d208d	154	#define STACK_WARN (THREAD_SIZE/8)
b84200b3	155
2052e8d4 CL	156	/*
	157	* macros/functions for gaining access to the thread information structure
	158	*
	159	* preempt_count needs to be 1 initially, until the scheduler is functional.
	160	*/
	161	#ifndef __ASSEMBLY__
	162
9af45651	163	static inline struct thread_info *current_thread_info(void)
2052e8d4	164	{
a7fcf28d	165	return (struct thread_info *)(current_top_of_stack() - THREAD_SIZE);
2052e8d4 CL	166	}
2052e8d4 CL	167
83653c16 AL	168	static inline unsigned long current_stack_pointer(void)
	169	{
	170	unsigned long sp;
	171	#ifdef CONFIG_X86_64
	172	asm("mov %%rsp,%0" : "=g" (sp));
	173	#else
	174	asm("mov %%esp,%0" : "=g" (sp));
	175	#endif
	176	return sp;
	177	}
	178
0f60a8ef KC	179	/*
	180	* Walks up the stack frames to make sure that the specified object is
	181	* entirely contained by a single stack frame.
	182	*
	183	* Returns:
	184	* 1 if within a frame
	185	* -1 if placed across a frame boundary (or outside stack)
	186	* 0 unable to determine (no frame pointers, etc)
	187	*/
	188	static inline int arch_within_stack_frames(const void * const stack,
	189	const void * const stackend,
	190	const void *obj, unsigned long len)
	191	{
	192	#if defined(CONFIG_FRAME_POINTER)
	193	const void *frame = NULL;
	194	const void *oldframe;
	195
	196	oldframe = __builtin_frame_address(1);
	197	if (oldframe)
	198	frame = __builtin_frame_address(2);
	199	/*
	200	* low ----------------------------------------------> high
	201	* [saved bp][saved ip][args][local vars][saved bp][saved ip]
	202	* ^----------------^
	203	* allow copies only within here
	204	*/
	205	while (stack <= frame && frame < stackend) {
	206	/*
	207	* If obj + len extends past the last frame, this
	208	* check won't pass and the next frame will be 0,
	209	* causing us to bail out and correctly report
	210	* the copy as invalid.
	211	*/
	212	if (obj + len <= frame)
	213	return obj >= oldframe + 2 * sizeof(void *) ? 1 : -1;
	214	oldframe = frame;
	215	frame = (const void const *)frame;
	216	}
	217	return -1;
	218	#else
	219	return 0;
	220	#endif
	221	}
	222
2052e8d4 CL	223	#else /* !__ASSEMBLY__ */
2052e8d4 CL	224
3a23208e DV	225	#ifdef CONFIG_X86_64
	226	# define cpu_current_top_of_stack (cpu_tss + TSS_sp0)
	227	#endif
	228
46db09d3	229	/*
1ddc6f3c IM	230	* ASM operand which evaluates to a 'thread_info' address of
	231	* the current task, if it is known that "reg" is exactly "off"
	232	* bytes below the top of the stack currently.
	233	*
	234	* ( The kernel stack's size is known at build time, it is usually
	235	* 2 or 4 pages, and the bottom of the kernel stack contains
	236	* the thread_info structure. So to access the thread_info very
	237	* quickly from assembly code we can calculate down from the
	238	* top of the kernel stack to the bottom, using constant,
	239	* build-time calculations only. )
	240	*
	241	* For example, to fetch the current thread_info->flags value into %eax
	242	* on x86-64 defconfig kernels, in syscall entry code where RSP is
	243	* currently at exactly SIZEOF_PTREGS bytes away from the top of the
	244	* stack:
	245	*
dca5b52a	246	* mov ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS), %eax
1ddc6f3c IM	247	*
	248	* will translate to:
	249	*
	250	* 8b 84 24 b8 c0 ff ff mov -0x3f48(%rsp), %eax
	251	*
	252	* which is below the current RSP by almost 16K.
46db09d3	253	*/
dca5b52a	254	#define ASM_THREAD_INFO(field, reg, off) ((field)+(off)-THREAD_SIZE)(reg)
46db09d3	255
2052e8d4 CL	256	#endif
2052e8d4 CL	257
2052e8d4 CL	258	/*
	259	* Thread-synchronous status.
	260	*
	261	* This is different from the flags in that nobody else
	262	* ever touches our thread-synchronous status, so we don't
	263	* have to worry about atomic accesses.
	264	*/
f2ea3b1d	265	#define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/
609c19a3 AL	266	#ifdef CONFIG_COMPAT
	267	#define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */
	268	#endif
2052e8d4	269
8a6c160a	270	#ifndef __ASSEMBLY__
ef334a20	271
abfb9498	272	static inline bool in_ia32_syscall(void)
ef334a20 SD	273	{
	274	#ifdef CONFIG_X86_32
	275	return true;
	276	#endif
	277	#ifdef CONFIG_IA32_EMULATION
	278	if (current_thread_info()->status & TS_COMPAT)
	279	return true;
	280	#endif
	281	return false;
	282	}
1daeaa31 BG	283
	284	/*
	285	* Force syscall return via IRET by making it look as if there was
	286	* some work pending. IRET is our most capable (but slowest) syscall
	287	* return path, which is able to restore modified SS, CS and certain
	288	* EFLAGS values that other (fast) syscall return instructions
	289	* are not able to restore properly.
	290	*/
	291	#define force_iret() set_thread_flag(TIF_NOTIFY_RESUME)
	292
61c4628b	293	extern void arch_task_cache_init(void);
61c4628b	294	extern int arch_dup_task_struct(struct task_struct dst, struct task_struct src);
38e7c572	295	extern void arch_release_task_struct(struct task_struct *tsk);
5f870a3f BP	296	#endif /* !__ASSEMBLY__ */
5f870a3f BP	297
1965aae3	298	#endif /* _ASM_X86_THREAD_INFO_H */