LXR linux/arch/x86/include/asm/thread

   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
   7#ifndef _ASM_X86_THREAD_INFO_H
   8#define _ASM_X86_THREAD_INFO_H
   9
  10#include <linux/compiler.h>
  11#include <asm/page.h>
  12#include <asm/percpu.h>
  13#include <asm/types.h>
  14
  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 *
  30 * In vm86 mode, the hardware frame is much longer still, so add 16
  31 * bytes to make room for the real-mode segments.
  32 *
  33 * x86_64 has a fixed-length stack frame.
  34 */
  35#ifdef CONFIG_X86_32
  36# ifdef CONFIG_VM86
  37#  define TOP_OF_KERNEL_STACK_PADDING 16
  38# else
  39#  define TOP_OF_KERNEL_STACK_PADDING 8
  40# endif
  41#else
  42# define TOP_OF_KERNEL_STACK_PADDING 0
  43#endif
  44
  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
  49 */
  50#ifndef __ASSEMBLY__
  51struct task_struct;
  52#include <asm/processor.h>
  53#include <linux/atomic.h>
  54
  55struct thread_info {
  56        struct task_struct      *task;          /* main task structure */
  57        __u32                   flags;          /* low level flags */
  58        __u32                   status;         /* thread synchronous flags */
  59        __u32                   cpu;            /* current CPU */
  60        mm_segment_t            addr_limit;
  61        unsigned int            sig_on_uaccess_error:1;
  62        unsigned int            uaccess_err:1;  /* uaccess failed */
  63};
  64
  65#define INIT_THREAD_INFO(tsk)                   \
  66{                                               \
  67        .task           = &tsk,                 \
  68        .flags          = 0,                    \
  69        .cpu            = 0,                    \
  70        .addr_limit     = KERNEL_DS,            \
  71}
  72
  73#define init_thread_info        (init_thread_union.thread_info)
  74#define init_stack              (init_thread_union.stack)
  75
  76#else /* !__ASSEMBLY__ */
  77
  78#include <asm/asm-offsets.h>
  79
  80#endif
  81
  82/*
  83 * thread information flags
  84 * - these are process state flags that various assembly files
  85 *   may need to access
  86 * - pending work-to-be-done flags are in LSW
  87 * - other flags in MSW
  88 * Warning: layout of LSW is hardcoded in entry.S
  89 */
  90#define TIF_SYSCALL_TRACE       0       /* syscall trace active */
  91#define TIF_NOTIFY_RESUME       1       /* callback before returning to user */
  92#define TIF_SIGPENDING          2       /* signal pending */
  93#define TIF_NEED_RESCHED        3       /* rescheduling necessary */
  94#define TIF_SINGLESTEP          4       /* reenable singlestep on user return*/
  95#define TIF_SYSCALL_EMU         6       /* syscall emulation active */
  96#define TIF_SYSCALL_AUDIT       7       /* syscall auditing active */
  97#define TIF_SECCOMP             8       /* secure computing */
  98#define TIF_USER_RETURN_NOTIFY  11      /* notify kernel of userspace return */
  99#define TIF_UPROBE              12      /* breakpointed or singlestepping */
 100#define TIF_NOTSC               16      /* TSC is not accessible in userland */
 101#define TIF_IA32                17      /* IA32 compatibility process */
 102#define TIF_FORK                18      /* ret_from_fork */
 103#define TIF_NOHZ                19      /* in adaptive nohz mode */
 104#define TIF_MEMDIE              20      /* is terminating due to OOM killer */
 105#define TIF_POLLING_NRFLAG      21      /* idle is polling for TIF_NEED_RESCHED */
 106#define TIF_IO_BITMAP           22      /* uses I/O bitmap */
 107#define TIF_FORCED_TF           24      /* true if TF in eflags artificially */
 108#define TIF_BLOCKSTEP           25      /* set when we want DEBUGCTLMSR_BTF */
 109#define TIF_LAZY_MMU_UPDATES    27      /* task is updating the mmu lazily */
 110#define TIF_SYSCALL_TRACEPOINT  28      /* syscall tracepoint instrumentation */
 111#define TIF_ADDR32              29      /* 32-bit address space on 64 bits */
 112#define TIF_X32                 30      /* 32-bit native x86-64 binary */
 113
 114#define _TIF_SYSCALL_TRACE      (1 << TIF_SYSCALL_TRACE)
 115#define _TIF_NOTIFY_RESUME      (1 << TIF_NOTIFY_RESUME)
 116#define _TIF_SIGPENDING         (1 << TIF_SIGPENDING)
 117#define _TIF_SINGLESTEP         (1 << TIF_SINGLESTEP)
 118#define _TIF_NEED_RESCHED       (1 << TIF_NEED_RESCHED)
 119#define _TIF_SYSCALL_EMU        (1 << TIF_SYSCALL_EMU)
 120#define _TIF_SYSCALL_AUDIT      (1 << TIF_SYSCALL_AUDIT)
 121#define _TIF_SECCOMP            (1 << TIF_SECCOMP)
 122#define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
 123#define _TIF_UPROBE             (1 << TIF_UPROBE)
 124#define _TIF_NOTSC              (1 << TIF_NOTSC)
 125#define _TIF_IA32               (1 << TIF_IA32)
 126#define _TIF_FORK               (1 << TIF_FORK)
 127#define _TIF_NOHZ               (1 << TIF_NOHZ)
 128#define _TIF_POLLING_NRFLAG     (1 << TIF_POLLING_NRFLAG)
 129#define _TIF_IO_BITMAP          (1 << TIF_IO_BITMAP)
 130#define _TIF_FORCED_TF          (1 << TIF_FORCED_TF)
 131#define _TIF_BLOCKSTEP          (1 << TIF_BLOCKSTEP)
 132#define _TIF_LAZY_MMU_UPDATES   (1 << TIF_LAZY_MMU_UPDATES)
 133#define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
 134#define _TIF_ADDR32             (1 << TIF_ADDR32)
 135#define _TIF_X32                (1 << TIF_X32)
 136
 137/* work to do in syscall_trace_enter() */
 138#define _TIF_WORK_SYSCALL_ENTRY \
 139        (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT |   \
 140         _TIF_SECCOMP | _TIF_SINGLESTEP | _TIF_SYSCALL_TRACEPOINT |     \
 141         _TIF_NOHZ)
 142
 143/* work to do on any return to user space */
 144#define _TIF_ALLWORK_MASK                                               \
 145        ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT |       \
 146        _TIF_NOHZ)
 147
 148/* flags to check in __switch_to() */
 149#define _TIF_WORK_CTXSW                                                 \
 150        (_TIF_IO_BITMAP|_TIF_NOTSC|_TIF_BLOCKSTEP)
 151
 152#define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY)
 153#define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)
 154
 155#define STACK_WARN              (THREAD_SIZE/8)
 156
 157/*
 158 * macros/functions for gaining access to the thread information structure
 159 *
 160 * preempt_count needs to be 1 initially, until the scheduler is functional.
 161 */
 162#ifndef __ASSEMBLY__
 163
 164static inline struct thread_info *current_thread_info(void)
 165{
 166        return (struct thread_info *)(current_top_of_stack() - THREAD_SIZE);
 167}
 168
 169static inline unsigned long current_stack_pointer(void)
 170{
 171        unsigned long sp;
 172#ifdef CONFIG_X86_64
 173        asm("mov %%rsp,%0" : "=g" (sp));
 174#else
 175        asm("mov %%esp,%0" : "=g" (sp));
 176#endif
 177        return sp;
 178}
 179
 180#else /* !__ASSEMBLY__ */
 181
 182#ifdef CONFIG_X86_64
 183# define cpu_current_top_of_stack (cpu_tss + TSS_sp0)
 184#endif
 185
 186/* Load thread_info address into "reg" */
 187#define GET_THREAD_INFO(reg) \
 188        _ASM_MOV PER_CPU_VAR(cpu_current_top_of_stack),reg ; \
 189        _ASM_SUB $(THREAD_SIZE),reg ;
 190
 191/*
 192 * ASM operand which evaluates to a 'thread_info' address of
 193 * the current task, if it is known that "reg" is exactly "off"
 194 * bytes below the top of the stack currently.
 195 *
 196 * ( The kernel stack's size is known at build time, it is usually
 197 *   2 or 4 pages, and the bottom  of the kernel stack contains
 198 *   the thread_info structure. So to access the thread_info very
 199 *   quickly from assembly code we can calculate down from the
 200 *   top of the kernel stack to the bottom, using constant,
 201 *   build-time calculations only. )
 202 *
 203 * For example, to fetch the current thread_info->flags value into %eax
 204 * on x86-64 defconfig kernels, in syscall entry code where RSP is
 205 * currently at exactly SIZEOF_PTREGS bytes away from the top of the
 206 * stack:
 207 *
 208 *      mov ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS), %eax
 209 *
 210 * will translate to:
 211 *
 212 *      8b 84 24 b8 c0 ff ff      mov    -0x3f48(%rsp), %eax
 213 *
 214 * which is below the current RSP by almost 16K.
 215 */
 216#define ASM_THREAD_INFO(field, reg, off) ((field)+(off)-THREAD_SIZE)(reg)
 217
 218#endif
 219
 220/*
 221 * Thread-synchronous status.
 222 *
 223 * This is different from the flags in that nobody else
 224 * ever touches our thread-synchronous status, so we don't
 225 * have to worry about atomic accesses.
 226 */
 227#define TS_COMPAT               0x0002  /* 32bit syscall active (64BIT)*/
 228#define TS_RESTORE_SIGMASK      0x0008  /* restore signal mask in do_signal() */
 229
 230#ifndef __ASSEMBLY__
 231#define HAVE_SET_RESTORE_SIGMASK        1
 232static inline void set_restore_sigmask(void)
 233{
 234        struct thread_info *ti = current_thread_info();
 235        ti->status |= TS_RESTORE_SIGMASK;
 236        WARN_ON(!test_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags));
 237}
 238static inline void clear_restore_sigmask(void)
 239{
 240        current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 241}
 242static inline bool test_restore_sigmask(void)
 243{
 244        return current_thread_info()->status & TS_RESTORE_SIGMASK;
 245}
 246static inline bool test_and_clear_restore_sigmask(void)
 247{
 248        struct thread_info *ti = current_thread_info();
 249        if (!(ti->status & TS_RESTORE_SIGMASK))
 250                return false;
 251        ti->status &= ~TS_RESTORE_SIGMASK;
 252        return true;
 253}
 254
 255static inline bool is_ia32_task(void)
 256{
 257#ifdef CONFIG_X86_32
 258        return true;
 259#endif
 260#ifdef CONFIG_IA32_EMULATION
 261        if (current_thread_info()->status & TS_COMPAT)
 262                return true;
 263#endif
 264        return false;
 265}
 266
 267/*
 268 * Force syscall return via IRET by making it look as if there was
 269 * some work pending. IRET is our most capable (but slowest) syscall
 270 * return path, which is able to restore modified SS, CS and certain
 271 * EFLAGS values that other (fast) syscall return instructions
 272 * are not able to restore properly.
 273 */
 274#define force_iret() set_thread_flag(TIF_NOTIFY_RESUME)
 275
 276#endif  /* !__ASSEMBLY__ */
 277
 278#ifndef __ASSEMBLY__
 279extern void arch_task_cache_init(void);
 280extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
 281extern void arch_release_task_struct(struct task_struct *tsk);
 282#endif
 283#endif /* _ASM_X86_THREAD_INFO_H */
 284