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 unsigned long flags; /* low level flags */ 57 }; 58 59 #define INIT_THREAD_INFO(tsk) \ 60 { \ 61 .flags = 0, \ 62 } 63 64 #define init_stack (init_thread_union.stack) 65 66 #else /* !__ASSEMBLY__ */ 67 68 #include <asm/asm-offsets.h> 69 70 #endif 71 72 /* 73 * thread information flags 74 * - these are process state flags that various assembly files 75 * may need to access 76 * - pending work-to-be-done flags are in LSW 77 * - other flags in MSW 78 * Warning: layout of LSW is hardcoded in entry.S 79 */ 80 #define TIF_SYSCALL_TRACE 0 /* syscall trace active */ 81 #define TIF_NOTIFY_RESUME 1 /* callback before returning to user */ 82 #define TIF_SIGPENDING 2 /* signal pending */ 83 #define TIF_NEED_RESCHED 3 /* rescheduling necessary */ 84 #define TIF_SINGLESTEP 4 /* reenable singlestep on user return*/ 85 #define TIF_SYSCALL_EMU 6 /* syscall emulation active */ 86 #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */ 87 #define TIF_SECCOMP 8 /* secure computing */ 88 #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */ 89 #define TIF_UPROBE 12 /* breakpointed or singlestepping */ 90 #define TIF_NOTSC 16 /* TSC is not accessible in userland */ 91 #define TIF_IA32 17 /* IA32 compatibility process */ 92 #define TIF_NOHZ 19 /* in adaptive nohz mode */ 93 #define TIF_MEMDIE 20 /* is terminating due to OOM killer */ 94 #define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */ 95 #define TIF_IO_BITMAP 22 /* uses I/O bitmap */ 96 #define TIF_FORCED_TF 24 /* true if TF in eflags artificially */ 97 #define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */ 98 #define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */ 99 #define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */ 100 #define TIF_ADDR32 29 /* 32-bit address space on 64 bits */ 101 #define TIF_X32 30 /* 32-bit native x86-64 binary */ 102 103 #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) 104 #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) 105 #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) 106 #define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP) 107 #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) 108 #define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU) 109 #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) 110 #define _TIF_SECCOMP (1 << TIF_SECCOMP) 111 #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY) 112 #define _TIF_UPROBE (1 << TIF_UPROBE) 113 #define _TIF_NOTSC (1 << TIF_NOTSC) 114 #define _TIF_IA32 (1 << TIF_IA32) 115 #define _TIF_NOHZ (1 << TIF_NOHZ) 116 #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG) 117 #define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP) 118 #define _TIF_FORCED_TF (1 << TIF_FORCED_TF) 119 #define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP) 120 #define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES) 121 #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT) 122 #define _TIF_ADDR32 (1 << TIF_ADDR32) 123 #define _TIF_X32 (1 << TIF_X32) 124 125 /* 126 * work to do in syscall_trace_enter(). Also includes TIF_NOHZ for 127 * enter_from_user_mode() 128 */ 129 #define _TIF_WORK_SYSCALL_ENTRY \ 130 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \ 131 _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \ 132 _TIF_NOHZ) 133 134 /* work to do on any return to user space */ 135 #define _TIF_ALLWORK_MASK \ 136 ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT | \ 137 _TIF_NOHZ) 138 139 /* flags to check in __switch_to() */ 140 #define _TIF_WORK_CTXSW \ 141 (_TIF_IO_BITMAP|_TIF_NOTSC|_TIF_BLOCKSTEP) 142 143 #define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY) 144 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW) 145 146 #define STACK_WARN (THREAD_SIZE/8) 147 148 /* 149 * macros/functions for gaining access to the thread information structure 150 * 151 * preempt_count needs to be 1 initially, until the scheduler is functional. 152 */ 153 #ifndef __ASSEMBLY__ 154 155 static inline unsigned long current_stack_pointer(void) 156 { 157 unsigned long sp; 158 #ifdef CONFIG_X86_64 159 asm("mov %%rsp,%0" : "=g" (sp)); 160 #else 161 asm("mov %%esp,%0" : "=g" (sp)); 162 #endif 163 return sp; 164 } 165 166 /* 167 * Walks up the stack frames to make sure that the specified object is 168 * entirely contained by a single stack frame. 169 * 170 * Returns: 171 * 1 if within a frame 172 * -1 if placed across a frame boundary (or outside stack) 173 * 0 unable to determine (no frame pointers, etc) 174 */ 175 static inline int arch_within_stack_frames(const void * const stack, 176 const void * const stackend, 177 const void *obj, unsigned long len) 178 { 179 #if defined(CONFIG_FRAME_POINTER) 180 const void *frame = NULL; 181 const void *oldframe; 182 183 oldframe = __builtin_frame_address(1); 184 if (oldframe) 185 frame = __builtin_frame_address(2); 186 /* 187 * low ----------------------------------------------> high 188 * [saved bp][saved ip][args][local vars][saved bp][saved ip] 189 * ^----------------^ 190 * allow copies only within here 191 */ 192 while (stack <= frame && frame < stackend) { 193 /* 194 * If obj + len extends past the last frame, this 195 * check won't pass and the next frame will be 0, 196 * causing us to bail out and correctly report 197 * the copy as invalid. 198 */ 199 if (obj + len <= frame) 200 return obj >= oldframe + 2 * sizeof(void *) ? 1 : -1; 201 oldframe = frame; 202 frame = *(const void * const *)frame; 203 } 204 return -1; 205 #else 206 return 0; 207 #endif 208 } 209 210 #else /* !__ASSEMBLY__ */ 211 212 #ifdef CONFIG_X86_64 213 # define cpu_current_top_of_stack (cpu_tss + TSS_sp0) 214 #endif 215 216 #endif 217 218 #ifdef CONFIG_COMPAT 219 #define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */ 220 #endif 221 #ifndef __ASSEMBLY__ 222 223 #ifdef CONFIG_X86_32 224 #define in_ia32_syscall() true 225 #else 226 #define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \ 227 current->thread.status & TS_COMPAT) 228 #endif 229 230 /* 231 * Force syscall return via IRET by making it look as if there was 232 * some work pending. IRET is our most capable (but slowest) syscall 233 * return path, which is able to restore modified SS, CS and certain 234 * EFLAGS values that other (fast) syscall return instructions 235 * are not able to restore properly. 236 */ 237 #define force_iret() set_thread_flag(TIF_NOTIFY_RESUME) 238 239 extern void arch_task_cache_init(void); 240 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); 241 extern void arch_release_task_struct(struct task_struct *tsk); 242 #endif /* !__ASSEMBLY__ */ 243 244 #endif /* _ASM_X86_THREAD_INFO_H */ 245