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 #include <asm/processor.h> 50 #include <linux/atomic.h> 51 52 struct thread_info { 53 struct task_struct *task; /* main task structure */ 54 __u32 flags; /* low level flags */ 55 __u32 status; /* thread synchronous flags */ 56 __u32 cpu; /* current CPU */ 57 int saved_preempt_count; 58 mm_segment_t addr_limit; 59 void __user *sysenter_return; 60 unsigned int sig_on_uaccess_error:1; 61 unsigned int uaccess_err:1; /* uaccess failed */ 62 }; 63 64 #define INIT_THREAD_INFO(tsk) \ 65 { \ 66 .task = &tsk, \ 67 .flags = 0, \ 68 .cpu = 0, \ 69 .saved_preempt_count = INIT_PREEMPT_COUNT, \ 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 in syscall_trace_leave() */ 144 #define _TIF_WORK_SYSCALL_EXIT \ 145 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SINGLESTEP | \ 146 _TIF_SYSCALL_TRACEPOINT | _TIF_NOHZ) 147 148 /* work to do on interrupt/exception return */ 149 #define _TIF_WORK_MASK \ 150 (0x0000FFFF & \ 151 ~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT| \ 152 _TIF_SINGLESTEP|_TIF_SECCOMP|_TIF_SYSCALL_EMU)) 153 154 /* work to do on any return to user space */ 155 #define _TIF_ALLWORK_MASK \ 156 ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT | \ 157 _TIF_NOHZ) 158 159 /* Only used for 64 bit */ 160 #define _TIF_DO_NOTIFY_MASK \ 161 (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | \ 162 _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE) 163 164 /* flags to check in __switch_to() */ 165 #define _TIF_WORK_CTXSW \ 166 (_TIF_IO_BITMAP|_TIF_NOTSC|_TIF_BLOCKSTEP) 167 168 #define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY) 169 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW) 170 171 #define STACK_WARN (THREAD_SIZE/8) 172 173 /* 174 * macros/functions for gaining access to the thread information structure 175 * 176 * preempt_count needs to be 1 initially, until the scheduler is functional. 177 */ 178 #ifndef __ASSEMBLY__ 179 180 DECLARE_PER_CPU(unsigned long, kernel_stack); 181 182 static inline struct thread_info *current_thread_info(void) 183 { 184 return (struct thread_info *)(current_top_of_stack() - THREAD_SIZE); 185 } 186 187 static inline unsigned long current_stack_pointer(void) 188 { 189 unsigned long sp; 190 #ifdef CONFIG_X86_64 191 asm("mov %%rsp,%0" : "=g" (sp)); 192 #else 193 asm("mov %%esp,%0" : "=g" (sp)); 194 #endif 195 return sp; 196 } 197 198 #else /* !__ASSEMBLY__ */ 199 200 /* Load thread_info address into "reg" */ 201 #define GET_THREAD_INFO(reg) \ 202 _ASM_MOV PER_CPU_VAR(kernel_stack),reg ; \ 203 _ASM_SUB $(THREAD_SIZE),reg ; 204 205 /* 206 * ASM operand which evaluates to a 'thread_info' address of 207 * the current task, if it is known that "reg" is exactly "off" 208 * bytes below the top of the stack currently. 209 * 210 * ( The kernel stack's size is known at build time, it is usually 211 * 2 or 4 pages, and the bottom of the kernel stack contains 212 * the thread_info structure. So to access the thread_info very 213 * quickly from assembly code we can calculate down from the 214 * top of the kernel stack to the bottom, using constant, 215 * build-time calculations only. ) 216 * 217 * For example, to fetch the current thread_info->flags value into %eax 218 * on x86-64 defconfig kernels, in syscall entry code where RSP is 219 * currently at exactly SIZEOF_PTREGS bytes away from the top of the 220 * stack: 221 * 222 * mov ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS), %eax 223 * 224 * will translate to: 225 * 226 * 8b 84 24 b8 c0 ff ff mov -0x3f48(%rsp), %eax 227 * 228 * which is below the current RSP by almost 16K. 229 */ 230 #define ASM_THREAD_INFO(field, reg, off) ((field)+(off)-THREAD_SIZE)(reg) 231 232 #endif 233 234 /* 235 * Thread-synchronous status. 236 * 237 * This is different from the flags in that nobody else 238 * ever touches our thread-synchronous status, so we don't 239 * have to worry about atomic accesses. 240 */ 241 #define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/ 242 #define TS_RESTORE_SIGMASK 0x0008 /* restore signal mask in do_signal() */ 243 244 #ifndef __ASSEMBLY__ 245 #define HAVE_SET_RESTORE_SIGMASK 1 246 static inline void set_restore_sigmask(void) 247 { 248 struct thread_info *ti = current_thread_info(); 249 ti->status |= TS_RESTORE_SIGMASK; 250 WARN_ON(!test_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags)); 251 } 252 static inline void clear_restore_sigmask(void) 253 { 254 current_thread_info()->status &= ~TS_RESTORE_SIGMASK; 255 } 256 static inline bool test_restore_sigmask(void) 257 { 258 return current_thread_info()->status & TS_RESTORE_SIGMASK; 259 } 260 static inline bool test_and_clear_restore_sigmask(void) 261 { 262 struct thread_info *ti = current_thread_info(); 263 if (!(ti->status & TS_RESTORE_SIGMASK)) 264 return false; 265 ti->status &= ~TS_RESTORE_SIGMASK; 266 return true; 267 } 268 269 static inline bool is_ia32_task(void) 270 { 271 #ifdef CONFIG_X86_32 272 return true; 273 #endif 274 #ifdef CONFIG_IA32_EMULATION 275 if (current_thread_info()->status & TS_COMPAT) 276 return true; 277 #endif 278 return false; 279 } 280 281 /* 282 * Force syscall return via IRET by making it look as if there was 283 * some work pending. IRET is our most capable (but slowest) syscall 284 * return path, which is able to restore modified SS, CS and certain 285 * EFLAGS values that other (fast) syscall return instructions 286 * are not able to restore properly. 287 */ 288 #define force_iret() set_thread_flag(TIF_NOTIFY_RESUME) 289 290 #endif /* !__ASSEMBLY__ */ 291 292 #ifndef __ASSEMBLY__ 293 extern void arch_task_cache_init(void); 294 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); 295 extern void arch_release_task_struct(struct task_struct *tsk); 296 #endif 297 #endif /* _ASM_X86_THREAD_INFO_H */ 298