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7c68af6e32
Add a general per-cpu notifier that is called whenever the kernel is about to return to userspace. The notifier uses a thread_info flag and existing checks, so there is no impact on user return or context switch fast paths. This will be used initially to speed up KVM task switching by lazily updating MSRs. Signed-off-by: Avi Kivity <avi@redhat.com> LKML-Reference: <1253342422-13811-1-git-send-email-avi@redhat.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
270 lines
8.4 KiB
C
270 lines
8.4 KiB
C
/* thread_info.h: low-level thread information
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*
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* Copyright (C) 2002 David Howells (dhowells@redhat.com)
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* - Incorporating suggestions made by Linus Torvalds and Dave Miller
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*/
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#ifndef _ASM_X86_THREAD_INFO_H
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#define _ASM_X86_THREAD_INFO_H
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#include <linux/compiler.h>
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#include <asm/page.h>
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#include <asm/types.h>
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/*
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* low level task data that entry.S needs immediate access to
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* - this struct should fit entirely inside of one cache line
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* - this struct shares the supervisor stack pages
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*/
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#ifndef __ASSEMBLY__
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struct task_struct;
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struct exec_domain;
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#include <asm/processor.h>
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#include <asm/ftrace.h>
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#include <asm/atomic.h>
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struct thread_info {
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struct task_struct *task; /* main task structure */
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struct exec_domain *exec_domain; /* execution domain */
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__u32 flags; /* low level flags */
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__u32 status; /* thread synchronous flags */
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__u32 cpu; /* current CPU */
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int preempt_count; /* 0 => preemptable,
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<0 => BUG */
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mm_segment_t addr_limit;
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struct restart_block restart_block;
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void __user *sysenter_return;
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#ifdef CONFIG_X86_32
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unsigned long previous_esp; /* ESP of the previous stack in
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case of nested (IRQ) stacks
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*/
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__u8 supervisor_stack[0];
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#endif
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int uaccess_err;
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};
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#define INIT_THREAD_INFO(tsk) \
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{ \
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.task = &tsk, \
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.exec_domain = &default_exec_domain, \
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.flags = 0, \
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.cpu = 0, \
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.preempt_count = INIT_PREEMPT_COUNT, \
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.addr_limit = KERNEL_DS, \
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.restart_block = { \
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.fn = do_no_restart_syscall, \
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}, \
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}
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#define init_thread_info (init_thread_union.thread_info)
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#define init_stack (init_thread_union.stack)
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#else /* !__ASSEMBLY__ */
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#include <asm/asm-offsets.h>
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#endif
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/*
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* thread information flags
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* - these are process state flags that various assembly files
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* may need to access
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* - pending work-to-be-done flags are in LSW
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* - other flags in MSW
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* Warning: layout of LSW is hardcoded in entry.S
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*/
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#define TIF_SYSCALL_TRACE 0 /* syscall trace active */
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#define TIF_NOTIFY_RESUME 1 /* callback before returning to user */
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#define TIF_SIGPENDING 2 /* signal pending */
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#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
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#define TIF_SINGLESTEP 4 /* reenable singlestep on user return*/
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#define TIF_IRET 5 /* force IRET */
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#define TIF_SYSCALL_EMU 6 /* syscall emulation active */
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#define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
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#define TIF_SECCOMP 8 /* secure computing */
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#define TIF_MCE_NOTIFY 10 /* notify userspace of an MCE */
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#define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */
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#define TIF_NOTSC 16 /* TSC is not accessible in userland */
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#define TIF_IA32 17 /* 32bit process */
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#define TIF_FORK 18 /* ret_from_fork */
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#define TIF_ABI_PENDING 19
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#define TIF_MEMDIE 20
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#define TIF_DEBUG 21 /* uses debug registers */
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#define TIF_IO_BITMAP 22 /* uses I/O bitmap */
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#define TIF_FREEZE 23 /* is freezing for suspend */
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#define TIF_FORCED_TF 24 /* true if TF in eflags artificially */
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#define TIF_DEBUGCTLMSR 25 /* uses thread_struct.debugctlmsr */
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#define TIF_DS_AREA_MSR 26 /* uses thread_struct.ds_area_msr */
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#define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */
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#define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */
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#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
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#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
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#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
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#define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
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#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
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#define _TIF_IRET (1 << TIF_IRET)
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#define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU)
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#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
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#define _TIF_SECCOMP (1 << TIF_SECCOMP)
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#define _TIF_MCE_NOTIFY (1 << TIF_MCE_NOTIFY)
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#define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
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#define _TIF_NOTSC (1 << TIF_NOTSC)
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#define _TIF_IA32 (1 << TIF_IA32)
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#define _TIF_FORK (1 << TIF_FORK)
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#define _TIF_ABI_PENDING (1 << TIF_ABI_PENDING)
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#define _TIF_DEBUG (1 << TIF_DEBUG)
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#define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
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#define _TIF_FREEZE (1 << TIF_FREEZE)
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#define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
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#define _TIF_DEBUGCTLMSR (1 << TIF_DEBUGCTLMSR)
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#define _TIF_DS_AREA_MSR (1 << TIF_DS_AREA_MSR)
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#define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES)
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#define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
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/* work to do in syscall_trace_enter() */
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#define _TIF_WORK_SYSCALL_ENTRY \
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(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \
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_TIF_SECCOMP | _TIF_SINGLESTEP | _TIF_SYSCALL_TRACEPOINT)
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/* work to do in syscall_trace_leave() */
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#define _TIF_WORK_SYSCALL_EXIT \
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(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SINGLESTEP | \
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_TIF_SYSCALL_TRACEPOINT)
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/* work to do on interrupt/exception return */
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#define _TIF_WORK_MASK \
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(0x0000FFFF & \
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~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT| \
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_TIF_SINGLESTEP|_TIF_SECCOMP|_TIF_SYSCALL_EMU))
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/* work to do on any return to user space */
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#define _TIF_ALLWORK_MASK \
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((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT)
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/* Only used for 64 bit */
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#define _TIF_DO_NOTIFY_MASK \
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(_TIF_SIGPENDING | _TIF_MCE_NOTIFY | _TIF_NOTIFY_RESUME | \
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_TIF_USER_RETURN_NOTIFY)
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/* flags to check in __switch_to() */
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#define _TIF_WORK_CTXSW \
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(_TIF_IO_BITMAP|_TIF_DEBUGCTLMSR|_TIF_DS_AREA_MSR|_TIF_NOTSC)
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#define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY)
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#define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW|_TIF_DEBUG)
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#define PREEMPT_ACTIVE 0x10000000
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/* thread information allocation */
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#ifdef CONFIG_DEBUG_STACK_USAGE
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#define THREAD_FLAGS (GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO)
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#else
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#define THREAD_FLAGS (GFP_KERNEL | __GFP_NOTRACK)
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#endif
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#define __HAVE_ARCH_THREAD_INFO_ALLOCATOR
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#define alloc_thread_info(tsk) \
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((struct thread_info *)__get_free_pages(THREAD_FLAGS, THREAD_ORDER))
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#ifdef CONFIG_X86_32
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#define STACK_WARN (THREAD_SIZE/8)
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/*
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* macros/functions for gaining access to the thread information structure
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*
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* preempt_count needs to be 1 initially, until the scheduler is functional.
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*/
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#ifndef __ASSEMBLY__
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/* how to get the current stack pointer from C */
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register unsigned long current_stack_pointer asm("esp") __used;
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/* how to get the thread information struct from C */
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static inline struct thread_info *current_thread_info(void)
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{
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return (struct thread_info *)
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(current_stack_pointer & ~(THREAD_SIZE - 1));
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}
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#else /* !__ASSEMBLY__ */
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/* how to get the thread information struct from ASM */
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#define GET_THREAD_INFO(reg) \
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movl $-THREAD_SIZE, reg; \
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andl %esp, reg
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/* use this one if reg already contains %esp */
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#define GET_THREAD_INFO_WITH_ESP(reg) \
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andl $-THREAD_SIZE, reg
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#endif
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#else /* X86_32 */
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#include <asm/percpu.h>
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#define KERNEL_STACK_OFFSET (5*8)
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/*
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* macros/functions for gaining access to the thread information structure
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* preempt_count needs to be 1 initially, until the scheduler is functional.
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*/
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#ifndef __ASSEMBLY__
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DECLARE_PER_CPU(unsigned long, kernel_stack);
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static inline struct thread_info *current_thread_info(void)
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{
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struct thread_info *ti;
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ti = (void *)(percpu_read_stable(kernel_stack) +
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KERNEL_STACK_OFFSET - THREAD_SIZE);
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return ti;
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}
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#else /* !__ASSEMBLY__ */
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/* how to get the thread information struct from ASM */
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#define GET_THREAD_INFO(reg) \
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movq PER_CPU_VAR(kernel_stack),reg ; \
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subq $(THREAD_SIZE-KERNEL_STACK_OFFSET),reg
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#endif
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#endif /* !X86_32 */
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/*
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* Thread-synchronous status.
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*
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* This is different from the flags in that nobody else
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* ever touches our thread-synchronous status, so we don't
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* have to worry about atomic accesses.
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*/
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#define TS_USEDFPU 0x0001 /* FPU was used by this task
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this quantum (SMP) */
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#define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/
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#define TS_POLLING 0x0004 /* true if in idle loop
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and not sleeping */
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#define TS_RESTORE_SIGMASK 0x0008 /* restore signal mask in do_signal() */
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#define TS_XSAVE 0x0010 /* Use xsave/xrstor */
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#define tsk_is_polling(t) (task_thread_info(t)->status & TS_POLLING)
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#ifndef __ASSEMBLY__
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#define HAVE_SET_RESTORE_SIGMASK 1
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static inline void set_restore_sigmask(void)
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{
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struct thread_info *ti = current_thread_info();
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ti->status |= TS_RESTORE_SIGMASK;
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set_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags);
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}
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#endif /* !__ASSEMBLY__ */
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#ifndef __ASSEMBLY__
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extern void arch_task_cache_init(void);
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extern void free_thread_info(struct thread_info *ti);
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extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
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#define arch_task_cache_init arch_task_cache_init
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#endif
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#endif /* _ASM_X86_THREAD_INFO_H */
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