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/cpufeature.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 }; 61 62 #define INIT_THREAD_INFO(tsk) \ 63 { \ 64 .task = &tsk, \ 65 .flags = 0, \ 66 .cpu = 0, \ 67 } 68 69 #define init_thread_info (init_thread_union.thread_info) 70 #define init_stack (init_thread_union.stack) 71 72 #else /* !__ASSEMBLY__ */ 73 74 #include <asm/asm-offsets.h> 75 76 #endif 77 78 /* 79 * thread information flags 80 * - these are process state flags that various assembly files 81 * may need to access 82 * - pending work-to-be-done flags are in LSW 83 * - other flags in MSW 84 * Warning: layout of LSW is hardcoded in entry.S 85 */ 86 #define TIF_SYSCALL_TRACE 0 /* syscall trace active */ 87 #define TIF_NOTIFY_RESUME 1 /* callback before returning to user */ 88 #define TIF_SIGPENDING 2 /* signal pending */ 89 #define TIF_NEED_RESCHED 3 /* rescheduling necessary */ 90 #define TIF_SINGLESTEP 4 /* reenable singlestep on user return*/ 91 #define TIF_SYSCALL_EMU 6 /* syscall emulation active */ 92 #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */ 93 #define TIF_SECCOMP 8 /* secure computing */ 94 #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */ 95 #define TIF_UPROBE 12 /* breakpointed or singlestepping */ 96 #define TIF_NOTSC 16 /* TSC is not accessible in userland */ 97 #define TIF_IA32 17 /* IA32 compatibility process */ 98 #define TIF_FORK 18 /* ret_from_fork */ 99 #define TIF_NOHZ 19 /* in adaptive nohz mode */ 100 #define TIF_MEMDIE 20 /* is terminating due to OOM killer */ 101 #define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */ 102 #define TIF_IO_BITMAP 22 /* uses I/O bitmap */ 103 #define TIF_FORCED_TF 24 /* true if TF in eflags artificially */ 104 #define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */ 105 #define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */ 106 #define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */ 107 #define TIF_ADDR32 29 /* 32-bit address space on 64 bits */ 108 #define TIF_X32 30 /* 32-bit native x86-64 binary */ 109 110 #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) 111 #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) 112 #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) 113 #define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP) 114 #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) 115 #define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU) 116 #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) 117 #define _TIF_SECCOMP (1 << TIF_SECCOMP) 118 #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY) 119 #define _TIF_UPROBE (1 << TIF_UPROBE) 120 #define _TIF_NOTSC (1 << TIF_NOTSC) 121 #define _TIF_IA32 (1 << TIF_IA32) 122 #define _TIF_FORK (1 << TIF_FORK) 123 #define _TIF_NOHZ (1 << TIF_NOHZ) 124 #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG) 125 #define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP) 126 #define _TIF_FORCED_TF (1 << TIF_FORCED_TF) 127 #define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP) 128 #define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES) 129 #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT) 130 #define _TIF_ADDR32 (1 << TIF_ADDR32) 131 #define _TIF_X32 (1 << TIF_X32) 132 133 /* 134 * work to do in syscall_trace_enter(). Also includes TIF_NOHZ for 135 * enter_from_user_mode() 136 */ 137 #define _TIF_WORK_SYSCALL_ENTRY \ 138 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \ 139 _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \ 140 _TIF_NOHZ) 141 142 /* work to do on any return to user space */ 143 #define _TIF_ALLWORK_MASK \ 144 ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT | \ 145 _TIF_NOHZ) 146 147 /* flags to check in __switch_to() */ 148 #define _TIF_WORK_CTXSW \ 149 (_TIF_IO_BITMAP|_TIF_NOTSC|_TIF_BLOCKSTEP) 150 151 #define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY) 152 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW) 153 154 #define STACK_WARN (THREAD_SIZE/8) 155 156 /* 157 * macros/functions for gaining access to the thread information structure 158 * 159 * preempt_count needs to be 1 initially, until the scheduler is functional. 160 */ 161 #ifndef __ASSEMBLY__ 162 163 static inline struct thread_info *current_thread_info(void) 164 { 165 return (struct thread_info *)(current_top_of_stack() - THREAD_SIZE); 166 } 167 168 static inline unsigned long current_stack_pointer(void) 169 { 170 unsigned long sp; 171 #ifdef CONFIG_X86_64 172 asm("mov %%rsp,%0" : "=g" (sp)); 173 #else 174 asm("mov %%esp,%0" : "=g" (sp)); 175 #endif 176 return sp; 177 } 178 179 #else /* !__ASSEMBLY__ */ 180 181 #ifdef CONFIG_X86_64 182 # define cpu_current_top_of_stack (cpu_tss + TSS_sp0) 183 #endif 184 185 /* 186 * ASM operand which evaluates to a 'thread_info' address of 187 * the current task, if it is known that "reg" is exactly "off" 188 * bytes below the top of the stack currently. 189 * 190 * ( The kernel stack's size is known at build time, it is usually 191 * 2 or 4 pages, and the bottom of the kernel stack contains 192 * the thread_info structure. So to access the thread_info very 193 * quickly from assembly code we can calculate down from the 194 * top of the kernel stack to the bottom, using constant, 195 * build-time calculations only. ) 196 * 197 * For example, to fetch the current thread_info->flags value into %eax 198 * on x86-64 defconfig kernels, in syscall entry code where RSP is 199 * currently at exactly SIZEOF_PTREGS bytes away from the top of the 200 * stack: 201 * 202 * mov ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS), %eax 203 * 204 * will translate to: 205 * 206 * 8b 84 24 b8 c0 ff ff mov -0x3f48(%rsp), %eax 207 * 208 * which is below the current RSP by almost 16K. 209 */ 210 #define ASM_THREAD_INFO(field, reg, off) ((field)+(off)-THREAD_SIZE)(reg) 211 212 #endif 213 214 /* 215 * Thread-synchronous status. 216 * 217 * This is different from the flags in that nobody else 218 * ever touches our thread-synchronous status, so we don't 219 * have to worry about atomic accesses. 220 */ 221 #define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/ 222 223 #ifndef __ASSEMBLY__ 224 225 static inline bool in_ia32_syscall(void) 226 { 227 #ifdef CONFIG_X86_32 228 return true; 229 #endif 230 #ifdef CONFIG_IA32_EMULATION 231 if (current_thread_info()->status & TS_COMPAT) 232 return true; 233 #endif 234 return false; 235 } 236 237 /* 238 * Force syscall return via IRET by making it look as if there was 239 * some work pending. IRET is our most capable (but slowest) syscall 240 * return path, which is able to restore modified SS, CS and certain 241 * EFLAGS values that other (fast) syscall return instructions 242 * are not able to restore properly. 243 */ 244 #define force_iret() set_thread_flag(TIF_NOTIFY_RESUME) 245 246 extern void arch_task_cache_init(void); 247 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); 248 extern void arch_release_task_struct(struct task_struct *tsk); 249 #endif /* !__ASSEMBLY__ */ 250 251 #endif /* _ASM_X86_THREAD_INFO_H */ 252