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) 175 176 /* 177 * macros/functions for gaining access to the thread information structure 178 * 179 * preempt_count needs to be 1 initially, until the scheduler is functional. 180 */ 181 #ifndef __ASSEMBLY__ 182 183 DECLARE_PER_CPU(unsigned long, kernel_stack); 184 185 static inline struct thread_info *current_thread_info(void) 186 { 187 return (struct thread_info *)(current_top_of_stack() - THREAD_SIZE); 188 } 189 190 static inline unsigned long current_stack_pointer(void) 191 { 192 unsigned long sp; 193 #ifdef CONFIG_X86_64 194 asm("mov %%rsp,%0" : "=g" (sp)); 195 #else 196 asm("mov %%esp,%0" : "=g" (sp)); 197 #endif 198 return sp; 199 } 200 201 #else /* !__ASSEMBLY__ */ 202 203 /* Load thread_info address into "reg" */ 204 #define GET_THREAD_INFO(reg) \ 205 _ASM_MOV PER_CPU_VAR(kernel_stack),reg ; \ 206 _ASM_SUB $(THREAD_SIZE),reg ; 207 208 /* 209 * ASM operand which evaluates to a 'thread_info' address of 210 * the current task, if it is known that "reg" is exactly "off" 211 * bytes below the top of the stack currently. 212 * 213 * ( The kernel stack's size is known at build time, it is usually 214 * 2 or 4 pages, and the bottom of the kernel stack contains 215 * the thread_info structure. So to access the thread_info very 216 * quickly from assembly code we can calculate down from the 217 * top of the kernel stack to the bottom, using constant, 218 * build-time calculations only. ) 219 * 220 * For example, to fetch the current thread_info->flags value into %eax 221 * on x86-64 defconfig kernels, in syscall entry code where RSP is 222 * currently at exactly SIZEOF_PTREGS bytes away from the top of the 223 * stack: 224 * 225 * mov THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS), %eax 226 * 227 * will translate to: 228 * 229 * 8b 84 24 b8 c0 ff ff mov -0x3f48(%rsp), %eax 230 * 231 * which is below the current RSP by almost 16K. 232 */ 233 #define THREAD_INFO(field, reg, off) ((field)+(off)-THREAD_SIZE)(reg) 234 235 #endif 236 237 /* 238 * Thread-synchronous status. 239 * 240 * This is different from the flags in that nobody else 241 * ever touches our thread-synchronous status, so we don't 242 * have to worry about atomic accesses. 243 */ 244 #define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/ 245 #define TS_RESTORE_SIGMASK 0x0008 /* restore signal mask in do_signal() */ 246 247 #ifndef __ASSEMBLY__ 248 #define HAVE_SET_RESTORE_SIGMASK 1 249 static inline void set_restore_sigmask(void) 250 { 251 struct thread_info *ti = current_thread_info(); 252 ti->status |= TS_RESTORE_SIGMASK; 253 WARN_ON(!test_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags)); 254 } 255 static inline void clear_restore_sigmask(void) 256 { 257 current_thread_info()->status &= ~TS_RESTORE_SIGMASK; 258 } 259 static inline bool test_restore_sigmask(void) 260 { 261 return current_thread_info()->status & TS_RESTORE_SIGMASK; 262 } 263 static inline bool test_and_clear_restore_sigmask(void) 264 { 265 struct thread_info *ti = current_thread_info(); 266 if (!(ti->status & TS_RESTORE_SIGMASK)) 267 return false; 268 ti->status &= ~TS_RESTORE_SIGMASK; 269 return true; 270 } 271 272 static inline bool is_ia32_task(void) 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 } 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) 292 293 #endif /* !__ASSEMBLY__ */ 294 295 #ifndef __ASSEMBLY__ 296 extern void arch_task_cache_init(void); 297 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); 298 extern void arch_release_task_struct(struct task_struct *tsk); 299 #endif 300 #endif /* _ASM_X86_THREAD_INFO_H */ 301