1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* thread_info.h: low-level thread information 3 * 4 * Copyright (C) 2002 David Howells (dhowells@redhat.com) 5 * - Incorporating suggestions made by Linus Torvalds and Dave Miller 6 */ 7 8 #ifndef _ASM_X86_THREAD_INFO_H 9 #define _ASM_X86_THREAD_INFO_H 10 11 #include <linux/compiler.h> 12 #include <asm/page.h> 13 #include <asm/percpu.h> 14 #include <asm/types.h> 15 16 /* 17 * TOP_OF_KERNEL_STACK_PADDING is a number of unused bytes that we 18 * reserve at the top of the kernel stack. We do it because of a nasty 19 * 32-bit corner case. On x86_32, the hardware stack frame is 20 * variable-length. Except for vm86 mode, struct pt_regs assumes a 21 * maximum-length frame. If we enter from CPL 0, the top 8 bytes of 22 * pt_regs don't actually exist. Ordinarily this doesn't matter, but it 23 * does in at least one case: 24 * 25 * If we take an NMI early enough in SYSENTER, then we can end up with 26 * pt_regs that extends above sp0. On the way out, in the espfix code, 27 * we can read the saved SS value, but that value will be above sp0. 28 * Without this offset, that can result in a page fault. (We are 29 * careful that, in this case, the value we read doesn't matter.) 30 * 31 * In vm86 mode, the hardware frame is much longer still, so add 16 32 * bytes to make room for the real-mode segments. 33 * 34 * x86_64 has a fixed-length stack frame. 35 */ 36 #ifdef CONFIG_X86_32 37 # ifdef CONFIG_VM86 38 # define TOP_OF_KERNEL_STACK_PADDING 16 39 # else 40 # define TOP_OF_KERNEL_STACK_PADDING 8 41 # endif 42 #else 43 # define TOP_OF_KERNEL_STACK_PADDING 0 44 #endif 45 46 /* 47 * low level task data that entry.S needs immediate access to 48 * - this struct should fit entirely inside of one cache line 49 * - this struct shares the supervisor stack pages 50 */ 51 #ifndef __ASSEMBLY__ 52 struct task_struct; 53 #include <asm/cpufeature.h> 54 #include <linux/atomic.h> 55 56 struct thread_info { 57 unsigned long flags; /* low level flags */ 58 }; 59 60 #define INIT_THREAD_INFO(tsk) \ 61 { \ 62 .flags = 0, \ 63 } 64 65 #define init_stack (init_thread_union.stack) 66 67 #else /* !__ASSEMBLY__ */ 68 69 #include <asm/asm-offsets.h> 70 71 #endif 72 73 /* 74 * thread information flags 75 * - these are process state flags that various assembly files 76 * may need to access 77 */ 78 #define TIF_SYSCALL_TRACE 0 /* syscall trace active */ 79 #define TIF_NOTIFY_RESUME 1 /* callback before returning to user */ 80 #define TIF_SIGPENDING 2 /* signal pending */ 81 #define TIF_NEED_RESCHED 3 /* rescheduling necessary */ 82 #define TIF_SINGLESTEP 4 /* reenable singlestep on user return*/ 83 #define TIF_SYSCALL_EMU 6 /* syscall emulation active */ 84 #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */ 85 #define TIF_SECCOMP 8 /* secure computing */ 86 #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */ 87 #define TIF_UPROBE 12 /* breakpointed or singlestepping */ 88 #define TIF_PATCH_PENDING 13 /* pending live patching update */ 89 #define TIF_NOCPUID 15 /* CPUID is not accessible in userland */ 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 #define TIF_FSCHECK 31 /* Check FS is USER_DS on return */ 103 104 #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) 105 #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) 106 #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) 107 #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) 108 #define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP) 109 #define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU) 110 #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) 111 #define _TIF_SECCOMP (1 << TIF_SECCOMP) 112 #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY) 113 #define _TIF_UPROBE (1 << TIF_UPROBE) 114 #define _TIF_PATCH_PENDING (1 << TIF_PATCH_PENDING) 115 #define _TIF_NOCPUID (1 << TIF_NOCPUID) 116 #define _TIF_NOTSC (1 << TIF_NOTSC) 117 #define _TIF_IA32 (1 << TIF_IA32) 118 #define _TIF_NOHZ (1 << TIF_NOHZ) 119 #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG) 120 #define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP) 121 #define _TIF_FORCED_TF (1 << TIF_FORCED_TF) 122 #define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP) 123 #define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES) 124 #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT) 125 #define _TIF_ADDR32 (1 << TIF_ADDR32) 126 #define _TIF_X32 (1 << TIF_X32) 127 #define _TIF_FSCHECK (1 << TIF_FSCHECK) 128 129 /* 130 * work to do in syscall_trace_enter(). Also includes TIF_NOHZ for 131 * enter_from_user_mode() 132 */ 133 #define _TIF_WORK_SYSCALL_ENTRY \ 134 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \ 135 _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \ 136 _TIF_NOHZ) 137 138 /* work to do on any return to user space */ 139 #define _TIF_ALLWORK_MASK \ 140 (_TIF_SYSCALL_TRACE | _TIF_NOTIFY_RESUME | _TIF_SIGPENDING | \ 141 _TIF_NEED_RESCHED | _TIF_SINGLESTEP | _TIF_SYSCALL_EMU | \ 142 _TIF_SYSCALL_AUDIT | _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE | \ 143 _TIF_PATCH_PENDING | _TIF_NOHZ | _TIF_SYSCALL_TRACEPOINT | \ 144 _TIF_FSCHECK) 145 146 /* flags to check in __switch_to() */ 147 #define _TIF_WORK_CTXSW \ 148 (_TIF_IO_BITMAP|_TIF_NOCPUID|_TIF_NOTSC|_TIF_BLOCKSTEP) 149 150 #define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY) 151 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW) 152 153 #define STACK_WARN (THREAD_SIZE/8) 154 155 /* 156 * macros/functions for gaining access to the thread information structure 157 * 158 * preempt_count needs to be 1 initially, until the scheduler is functional. 159 */ 160 #ifndef __ASSEMBLY__ 161 162 /* 163 * Walks up the stack frames to make sure that the specified object is 164 * entirely contained by a single stack frame. 165 * 166 * Returns: 167 * GOOD_FRAME if within a frame 168 * BAD_STACK if placed across a frame boundary (or outside stack) 169 * NOT_STACK unable to determine (no frame pointers, etc) 170 */ 171 static inline int arch_within_stack_frames(const void * const stack, 172 const void * const stackend, 173 const void *obj, unsigned long len) 174 { 175 #if defined(CONFIG_FRAME_POINTER) 176 const void *frame = NULL; 177 const void *oldframe; 178 179 oldframe = __builtin_frame_address(1); 180 if (oldframe) 181 frame = __builtin_frame_address(2); 182 /* 183 * low ----------------------------------------------> high 184 * [saved bp][saved ip][args][local vars][saved bp][saved ip] 185 * ^----------------^ 186 * allow copies only within here 187 */ 188 while (stack <= frame && frame < stackend) { 189 /* 190 * If obj + len extends past the last frame, this 191 * check won't pass and the next frame will be 0, 192 * causing us to bail out and correctly report 193 * the copy as invalid. 194 */ 195 if (obj + len <= frame) 196 return obj >= oldframe + 2 * sizeof(void *) ? 197 GOOD_FRAME : BAD_STACK; 198 oldframe = frame; 199 frame = *(const void * const *)frame; 200 } 201 return BAD_STACK; 202 #else 203 return NOT_STACK; 204 #endif 205 } 206 207 #else /* !__ASSEMBLY__ */ 208 209 #ifdef CONFIG_X86_64 210 # define cpu_current_top_of_stack (cpu_tss + TSS_sp0) 211 #endif 212 213 #endif 214 215 #ifdef CONFIG_COMPAT 216 #define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */ 217 #endif 218 #ifndef __ASSEMBLY__ 219 220 #ifdef CONFIG_X86_32 221 #define in_ia32_syscall() true 222 #else 223 #define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \ 224 current->thread.status & TS_COMPAT) 225 #endif 226 227 /* 228 * Force syscall return via IRET by making it look as if there was 229 * some work pending. IRET is our most capable (but slowest) syscall 230 * return path, which is able to restore modified SS, CS and certain 231 * EFLAGS values that other (fast) syscall return instructions 232 * are not able to restore properly. 233 */ 234 #define force_iret() set_thread_flag(TIF_NOTIFY_RESUME) 235 236 extern void arch_task_cache_init(void); 237 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); 238 extern void arch_release_task_struct(struct task_struct *tsk); 239 extern void arch_setup_new_exec(void); 240 #define arch_setup_new_exec arch_setup_new_exec 241 #endif /* !__ASSEMBLY__ */ 242 243 #endif /* _ASM_X86_THREAD_INFO_H */ 244