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, but we neither 31 * access the extra members from NMI context, nor do we write such a 32 * frame at sp0 at all. 33 * 34 * x86_64 has a fixed-length stack frame. 35 */ 36 #ifdef CONFIG_X86_32 37 # define TOP_OF_KERNEL_STACK_PADDING 8 38 #else 39 # define TOP_OF_KERNEL_STACK_PADDING 0 40 #endif 41 42 /* 43 * low level task data that entry.S needs immediate access to 44 * - this struct should fit entirely inside of one cache line 45 * - this struct shares the supervisor stack pages 46 */ 47 #ifndef __ASSEMBLY__ 48 struct task_struct; 49 struct exec_domain; 50 #include <asm/processor.h> 51 #include <linux/atomic.h> 52 53 struct thread_info { 54 struct task_struct *task; /* main task structure */ 55 struct exec_domain *exec_domain; /* execution domain */ 56 __u32 flags; /* low level flags */ 57 __u32 status; /* thread synchronous flags */ 58 __u32 cpu; /* current CPU */ 59 int saved_preempt_count; 60 mm_segment_t addr_limit; 61 void __user *sysenter_return; 62 unsigned int sig_on_uaccess_error:1; 63 unsigned int uaccess_err:1; /* uaccess failed */ 64 }; 65 66 #define INIT_THREAD_INFO(tsk) \ 67 { \ 68 .task = &tsk, \ 69 .exec_domain = &default_exec_domain, \ 70 .flags = 0, \ 71 .cpu = 0, \ 72 .saved_preempt_count = INIT_PREEMPT_COUNT, \ 73 .addr_limit = KERNEL_DS, \ 74 } 75 76 #define init_thread_info (init_thread_union.thread_info) 77 #define init_stack (init_thread_union.stack) 78 79 #else /* !__ASSEMBLY__ */ 80 81 #include <asm/asm-offsets.h> 82 83 #endif 84 85 /* 86 * thread information flags 87 * - these are process state flags that various assembly files 88 * may need to access 89 * - pending work-to-be-done flags are in LSW 90 * - other flags in MSW 91 * Warning: layout of LSW is hardcoded in entry.S 92 */ 93 #define TIF_SYSCALL_TRACE 0 /* syscall trace active */ 94 #define TIF_NOTIFY_RESUME 1 /* callback before returning to user */ 95 #define TIF_SIGPENDING 2 /* signal pending */ 96 #define TIF_NEED_RESCHED 3 /* rescheduling necessary */ 97 #define TIF_SINGLESTEP 4 /* reenable singlestep on user return*/ 98 #define TIF_SYSCALL_EMU 6 /* syscall emulation active */ 99 #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */ 100 #define TIF_SECCOMP 8 /* secure computing */ 101 #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */ 102 #define TIF_UPROBE 12 /* breakpointed or singlestepping */ 103 #define TIF_NOTSC 16 /* TSC is not accessible in userland */ 104 #define TIF_IA32 17 /* IA32 compatibility process */ 105 #define TIF_FORK 18 /* ret_from_fork */ 106 #define TIF_NOHZ 19 /* in adaptive nohz mode */ 107 #define TIF_MEMDIE 20 /* is terminating due to OOM killer */ 108 #define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */ 109 #define TIF_IO_BITMAP 22 /* uses I/O bitmap */ 110 #define TIF_FORCED_TF 24 /* true if TF in eflags artificially */ 111 #define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */ 112 #define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */ 113 #define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */ 114 #define TIF_ADDR32 29 /* 32-bit address space on 64 bits */ 115 #define TIF_X32 30 /* 32-bit native x86-64 binary */ 116 117 #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) 118 #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) 119 #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) 120 #define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP) 121 #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) 122 #define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU) 123 #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) 124 #define _TIF_SECCOMP (1 << TIF_SECCOMP) 125 #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY) 126 #define _TIF_UPROBE (1 << TIF_UPROBE) 127 #define _TIF_NOTSC (1 << TIF_NOTSC) 128 #define _TIF_IA32 (1 << TIF_IA32) 129 #define _TIF_FORK (1 << TIF_FORK) 130 #define _TIF_NOHZ (1 << TIF_NOHZ) 131 #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG) 132 #define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP) 133 #define _TIF_FORCED_TF (1 << TIF_FORCED_TF) 134 #define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP) 135 #define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES) 136 #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT) 137 #define _TIF_ADDR32 (1 << TIF_ADDR32) 138 #define _TIF_X32 (1 << TIF_X32) 139 140 /* work to do in syscall_trace_enter() */ 141 #define _TIF_WORK_SYSCALL_ENTRY \ 142 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \ 143 _TIF_SECCOMP | _TIF_SINGLESTEP | _TIF_SYSCALL_TRACEPOINT | \ 144 _TIF_NOHZ) 145 146 /* work to do in syscall_trace_leave() */ 147 #define _TIF_WORK_SYSCALL_EXIT \ 148 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SINGLESTEP | \ 149 _TIF_SYSCALL_TRACEPOINT | _TIF_NOHZ) 150 151 /* work to do on interrupt/exception return */ 152 #define _TIF_WORK_MASK \ 153 (0x0000FFFF & \ 154 ~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT| \ 155 _TIF_SINGLESTEP|_TIF_SECCOMP|_TIF_SYSCALL_EMU)) 156 157 /* work to do on any return to user space */ 158 #define _TIF_ALLWORK_MASK \ 159 ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT | \ 160 _TIF_NOHZ) 161 162 /* Only used for 64 bit */ 163 #define _TIF_DO_NOTIFY_MASK \ 164 (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | \ 165 _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE) 166 167 /* flags to check in __switch_to() */ 168 #define _TIF_WORK_CTXSW \ 169 (_TIF_IO_BITMAP|_TIF_NOTSC|_TIF_BLOCKSTEP) 170 171 #define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY) 172 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW) 173 174 #define STACK_WARN (THREAD_SIZE/8) 175 #define KERNEL_STACK_OFFSET (5*(BITS_PER_LONG/8)) 176 177 /* 178 * macros/functions for gaining access to the thread information structure 179 * 180 * preempt_count needs to be 1 initially, until the scheduler is functional. 181 */ 182 #ifndef __ASSEMBLY__ 183 184 DECLARE_PER_CPU(unsigned long, kernel_stack); 185 186 static inline struct thread_info *current_thread_info(void) 187 { 188 return (struct thread_info *)(current_top_of_stack() - THREAD_SIZE); 189 } 190 191 static inline unsigned long current_stack_pointer(void) 192 { 193 unsigned long sp; 194 #ifdef CONFIG_X86_64 195 asm("mov %%rsp,%0" : "=g" (sp)); 196 #else 197 asm("mov %%esp,%0" : "=g" (sp)); 198 #endif 199 return sp; 200 } 201 202 #else /* !__ASSEMBLY__ */ 203 204 /* how to get the thread information struct from ASM */ 205 #define GET_THREAD_INFO(reg) \ 206 _ASM_MOV PER_CPU_VAR(kernel_stack),reg ; \ 207 _ASM_SUB $(THREAD_SIZE-KERNEL_STACK_OFFSET),reg ; 208 209 /* 210 * ASM operand which evaluates to thread_info address 211 * if it is known that "reg" is exactly "off" bytes below stack top. 212 * Example (fetch thread_info->fieldname): 213 * mov TI_fieldname+THREAD_INFO(reg, off),%eax 214 */ 215 #define THREAD_INFO(reg, off) ((off)-THREAD_SIZE)(reg) 216 217 #endif 218 219 /* 220 * Thread-synchronous status. 221 * 222 * This is different from the flags in that nobody else 223 * ever touches our thread-synchronous status, so we don't 224 * have to worry about atomic accesses. 225 */ 226 #define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/ 227 #define TS_RESTORE_SIGMASK 0x0008 /* restore signal mask in do_signal() */ 228 229 #ifndef __ASSEMBLY__ 230 #define HAVE_SET_RESTORE_SIGMASK 1 231 static inline void set_restore_sigmask(void) 232 { 233 struct thread_info *ti = current_thread_info(); 234 ti->status |= TS_RESTORE_SIGMASK; 235 WARN_ON(!test_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags)); 236 } 237 static inline void clear_restore_sigmask(void) 238 { 239 current_thread_info()->status &= ~TS_RESTORE_SIGMASK; 240 } 241 static inline bool test_restore_sigmask(void) 242 { 243 return current_thread_info()->status & TS_RESTORE_SIGMASK; 244 } 245 static inline bool test_and_clear_restore_sigmask(void) 246 { 247 struct thread_info *ti = current_thread_info(); 248 if (!(ti->status & TS_RESTORE_SIGMASK)) 249 return false; 250 ti->status &= ~TS_RESTORE_SIGMASK; 251 return true; 252 } 253 254 static inline bool is_ia32_task(void) 255 { 256 #ifdef CONFIG_X86_32 257 return true; 258 #endif 259 #ifdef CONFIG_IA32_EMULATION 260 if (current_thread_info()->status & TS_COMPAT) 261 return true; 262 #endif 263 return false; 264 } 265 266 /* 267 * Force syscall return via IRET by making it look as if there was 268 * some work pending. IRET is our most capable (but slowest) syscall 269 * return path, which is able to restore modified SS, CS and certain 270 * EFLAGS values that other (fast) syscall return instructions 271 * are not able to restore properly. 272 */ 273 #define force_iret() set_thread_flag(TIF_NOTIFY_RESUME) 274 275 #endif /* !__ASSEMBLY__ */ 276 277 #ifndef __ASSEMBLY__ 278 extern void arch_task_cache_init(void); 279 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); 280 extern void arch_release_task_struct(struct task_struct *tsk); 281 #endif 282 #endif /* _ASM_X86_THREAD_INFO_H */ 283