arch/x86/include/asm/thread_info.h - kernel/common - Git at Google

 /* 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/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 */
 	mm_segment_t		addr_limit;
 	unsigned int		sig_on_uaccess_error:1;
 	unsigned int		uaccess_err:1;	/* uaccess failed */
 };

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

 #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;
 }

 #else /* !__ASSEMBLY__ */

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

 /* Load thread_info address into "reg" */
 #define GET_THREAD_INFO(reg) \
 	_ASM_MOV PER_CPU_VAR(cpu_current_top_of_stack),reg ; \
 	_ASM_SUB $(THREAD_SIZE),reg ;

 /*
  * 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)*/
 #define TS_RESTORE_SIGMASK	0x0008	/* restore signal mask in do_signal() */

 #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 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 */
	/* 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/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 */
	mm_segment_t addr_limit;
	unsigned int sig_on_uaccess_error:1;
	unsigned int uaccess_err:1; /* uaccess failed */
	};

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

	#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;
	}

	#else /* !__ASSEMBLY__ */

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

	/* Load thread_info address into "reg" */
	#define GET_THREAD_INFO(reg) \
	_ASM_MOV PER_CPU_VAR(cpu_current_top_of_stack),reg ; \
	_ASM_SUB $(THREAD_SIZE),reg ;

	/*
	* 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)*/
	#define TS_RESTORE_SIGMASK 0x0008 /* restore signal mask in do_signal() */

	#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 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 */