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 #define init_stack (init_thread_union.stack) 56 57 #else /* !__ASSEMBLY__ */ 58 59 #include <asm/asm-offsets.h> 60 61 #endif 62 63 /* 64 * thread information flags 65 * - these are process state flags that various assembly files 66 * may need to access 67 * - pending work-to-be-done flags are in LSW 68 * - other flags in MSW 69 * Warning: layout of LSW is hardcoded in entry.S 70 */ 71 #define TIF_SYSCALL_TRACE 0 /* syscall trace active */ 72 #define TIF_NOTIFY_RESUME 1 /* callback before returning to user */ 73 #define TIF_SIGPENDING 2 /* signal pending */ 74 #define TIF_NEED_RESCHED 3 /* rescheduling necessary */ 75 #define TIF_SINGLESTEP 4 /* reenable singlestep on user return*/ 76 #define TIF_SYSCALL_EMU 6 /* syscall emulation active */ 77 #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */ 78 #define TIF_SECCOMP 8 /* secure computing */ 79 #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */ 80 #define TIF_UPROBE 12 /* breakpointed or singlestepping */ 81 #define TIF_NOTSC 16 /* TSC is not accessible in userland */ 82 #define TIF_IA32 17 /* IA32 compatibility process */ 83 #define TIF_NOHZ 19 /* in adaptive nohz mode */ 84 #define TIF_MEMDIE 20 /* is terminating due to OOM killer */ 85 #define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */ 86 #define TIF_IO_BITMAP 22 /* uses I/O bitmap */ 87 #define TIF_FORCED_TF 24 /* true if TF in eflags artificially */ 88 #define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */ 89 #define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */ 90 #define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */ 91 #define TIF_ADDR32 29 /* 32-bit address space on 64 bits */ 92 #define TIF_X32 30 /* 32-bit native x86-64 binary */ 93 94 #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) 95 #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) 96 #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) 97 #define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP) 98 #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) 99 #define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU) 100 #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) 101 #define _TIF_SECCOMP (1 << TIF_SECCOMP) 102 #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY) 103 #define _TIF_UPROBE (1 << TIF_UPROBE) 104 #define _TIF_NOTSC (1 << TIF_NOTSC) 105 #define _TIF_IA32 (1 << TIF_IA32) 106 #define _TIF_NOHZ (1 << TIF_NOHZ) 107 #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG) 108 #define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP) 109 #define _TIF_FORCED_TF (1 << TIF_FORCED_TF) 110 #define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP) 111 #define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES) 112 #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT) 113 #define _TIF_ADDR32 (1 << TIF_ADDR32) 114 #define _TIF_X32 (1 << TIF_X32) 115 116 /* 117 * work to do in syscall_trace_enter(). Also includes TIF_NOHZ for 118 * enter_from_user_mode() 119 */ 120 #define _TIF_WORK_SYSCALL_ENTRY \ 121 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \ 122 _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \ 123 _TIF_NOHZ) 124 125 /* work to do on any return to user space */ 126 #define _TIF_ALLWORK_MASK \ 127 ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT | \ 128 _TIF_NOHZ) 129 130 /* flags to check in __switch_to() */ 131 #define _TIF_WORK_CTXSW \ 132 (_TIF_IO_BITMAP|_TIF_NOTSC|_TIF_BLOCKSTEP) 133 134 #define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY) 135 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW) 136 137 #define STACK_WARN (THREAD_SIZE/8) 138 139 /* 140 * macros/functions for gaining access to the thread information structure 141 * 142 * preempt_count needs to be 1 initially, until the scheduler is functional. 143 */ 144 #ifndef __ASSEMBLY__ 145 146 static inline unsigned long current_stack_pointer(void) 147 { 148 unsigned long sp; 149 #ifdef CONFIG_X86_64 150 asm("mov %%rsp,%0" : "=g" (sp)); 151 #else 152 asm("mov %%esp,%0" : "=g" (sp)); 153 #endif 154 return sp; 155 } 156 157 /* 158 * Walks up the stack frames to make sure that the specified object is 159 * entirely contained by a single stack frame. 160 * 161 * Returns: 162 * 1 if within a frame 163 * -1 if placed across a frame boundary (or outside stack) 164 * 0 unable to determine (no frame pointers, etc) 165 */ 166 static inline int arch_within_stack_frames(const void * const stack, 167 const void * const stackend, 168 const void *obj, unsigned long len) 169 { 170 #if defined(CONFIG_FRAME_POINTER) 171 const void *frame = NULL; 172 const void *oldframe; 173 174 oldframe = __builtin_frame_address(1); 175 if (oldframe) 176 frame = __builtin_frame_address(2); 177 /* 178 * low ----------------------------------------------> high 179 * [saved bp][saved ip][args][local vars][saved bp][saved ip] 180 * ^----------------^ 181 * allow copies only within here 182 */ 183 while (stack <= frame && frame < stackend) { 184 /* 185 * If obj + len extends past the last frame, this 186 * check won't pass and the next frame will be 0, 187 * causing us to bail out and correctly report 188 * the copy as invalid. 189 */ 190 if (obj + len <= frame) 191 return obj >= oldframe + 2 * sizeof(void *) ? 1 : -1; 192 oldframe = frame; 193 frame = *(const void * const *)frame; 194 } 195 return -1; 196 #else 197 return 0; 198 #endif 199 } 200 201 #else /* !__ASSEMBLY__ */ 202 203 #ifdef CONFIG_X86_64 204 # define cpu_current_top_of_stack (cpu_tss + TSS_sp0) 205 #endif 206 207 #endif 208 209 #ifdef CONFIG_COMPAT 210 #define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */ 211 #endif 212 #ifndef __ASSEMBLY__ 213 214 #ifdef CONFIG_X86_32 215 #define in_ia32_syscall() true 216 #else 217 #define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \ 218 current->thread.status & TS_COMPAT) 219 #endif 220 221 /* 222 * Force syscall return via IRET by making it look as if there was 223 * some work pending. IRET is our most capable (but slowest) syscall 224 * return path, which is able to restore modified SS, CS and certain 225 * EFLAGS values that other (fast) syscall return instructions 226 * are not able to restore properly. 227 */ 228 #define force_iret() set_thread_flag(TIF_NOTIFY_RESUME) 229 230 extern void arch_task_cache_init(void); 231 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); 232 extern void arch_release_task_struct(struct task_struct *tsk); 233 #endif /* !__ASSEMBLY__ */ 234 235 #endif /* _ASM_X86_THREAD_INFO_H */ 236