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__ 51 struct task_struct; 52 #include <asm/processor.h> 53 #include <linux/atomic.h> 54 55 struct 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__ 163 164 static inline struct thread_info *current_thread_info(void) 165 { 166 return (struct thread_info *)(current_top_of_stack() - THREAD_SIZE); 167 } 168 169 static 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 1 232 static 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 } 238 static inline void clear_restore_sigmask(void) 239 { 240 current_thread_info()->status &= ~TS_RESTORE_SIGMASK; 241 } 242 static inline bool test_restore_sigmask(void) 243 { 244 return current_thread_info()->status & TS_RESTORE_SIGMASK; 245 } 246 static 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 } 254 255 static 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__ 279 extern void arch_task_cache_init(void); 280 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); 281 extern void arch_release_task_struct(struct task_struct *tsk); 282 #endif 283 #endif /* _ASM_X86_THREAD_INFO_H */ 284