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, but it depends on whether 35 * or not FRED is enabled. Future versions of FRED might make this 36 * dynamic, but for now it is always 2 words longer. 37 */ 38 #ifdef CONFIG_X86_32 39 # ifdef CONFIG_VM86 40 # define TOP_OF_KERNEL_STACK_PADDING 16 41 # else 42 # define TOP_OF_KERNEL_STACK_PADDING 8 43 # endif 44 #else /* x86-64 */ 45 # ifdef CONFIG_X86_FRED 46 # define TOP_OF_KERNEL_STACK_PADDING (2 * 8) 47 # else 48 # define TOP_OF_KERNEL_STACK_PADDING 0 49 # endif 50 #endif 51 52 /* 53 * low level task data that entry.S needs immediate access to 54 * - this struct should fit entirely inside of one cache line 55 * - this struct shares the supervisor stack pages 56 */ 57 #ifndef __ASSEMBLY__ 58 struct task_struct; 59 #include <asm/cpufeature.h> 60 #include <linux/atomic.h> 61 62 struct thread_info { 63 unsigned long flags; /* low level flags */ 64 unsigned long syscall_work; /* SYSCALL_WORK_ flags */ 65 u32 status; /* thread synchronous flags */ 66 #ifdef CONFIG_SMP 67 u32 cpu; /* current CPU */ 68 #endif 69 }; 70 71 #define INIT_THREAD_INFO(tsk) \ 72 { \ 73 .flags = 0, \ 74 } 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 */ 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_NEED_RESCHED_LAZY 4 /* Lazy rescheduling needed */ 91 #define TIF_SINGLESTEP 5 /* reenable singlestep on user return*/ 92 #define TIF_SSBD 6 /* Speculative store bypass disable */ 93 #define TIF_SPEC_IB 9 /* Indirect branch speculation mitigation */ 94 #define TIF_SPEC_L1D_FLUSH 10 /* Flush L1D on mm switches (processes) */ 95 #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */ 96 #define TIF_UPROBE 12 /* breakpointed or singlestepping */ 97 #define TIF_PATCH_PENDING 13 /* pending live patching update */ 98 #define TIF_NEED_FPU_LOAD 14 /* load FPU on return to userspace */ 99 #define TIF_NOCPUID 15 /* CPUID is not accessible in userland */ 100 #define TIF_NOTSC 16 /* TSC is not accessible in userland */ 101 #define TIF_NOTIFY_SIGNAL 17 /* signal notifications exist */ 102 #define TIF_MEMDIE 20 /* is terminating due to OOM killer */ 103 #define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */ 104 #define TIF_IO_BITMAP 22 /* uses I/O bitmap */ 105 #define TIF_SPEC_FORCE_UPDATE 23 /* Force speculation MSR update in context switch */ 106 #define TIF_FORCED_TF 24 /* true if TF in eflags artificially */ 107 #define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */ 108 #define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */ 109 #define TIF_ADDR32 29 /* 32-bit address space on 64 bits */ 110 111 #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) 112 #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) 113 #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) 114 #define _TIF_NEED_RESCHED_LAZY (1 << TIF_NEED_RESCHED_LAZY) 115 #define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP) 116 #define _TIF_SSBD (1 << TIF_SSBD) 117 #define _TIF_SPEC_IB (1 << TIF_SPEC_IB) 118 #define _TIF_SPEC_L1D_FLUSH (1 << TIF_SPEC_L1D_FLUSH) 119 #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY) 120 #define _TIF_UPROBE (1 << TIF_UPROBE) 121 #define _TIF_PATCH_PENDING (1 << TIF_PATCH_PENDING) 122 #define _TIF_NEED_FPU_LOAD (1 << TIF_NEED_FPU_LOAD) 123 #define _TIF_NOCPUID (1 << TIF_NOCPUID) 124 #define _TIF_NOTSC (1 << TIF_NOTSC) 125 #define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL) 126 #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG) 127 #define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP) 128 #define _TIF_SPEC_FORCE_UPDATE (1 << TIF_SPEC_FORCE_UPDATE) 129 #define _TIF_FORCED_TF (1 << TIF_FORCED_TF) 130 #define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP) 131 #define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES) 132 #define _TIF_ADDR32 (1 << TIF_ADDR32) 133 134 /* flags to check in __switch_to() */ 135 #define _TIF_WORK_CTXSW_BASE \ 136 (_TIF_NOCPUID | _TIF_NOTSC | _TIF_BLOCKSTEP | \ 137 _TIF_SSBD | _TIF_SPEC_FORCE_UPDATE) 138 139 /* 140 * Avoid calls to __switch_to_xtra() on UP as STIBP is not evaluated. 141 */ 142 #ifdef CONFIG_SMP 143 # define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE | _TIF_SPEC_IB) 144 #else 145 # define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE) 146 #endif 147 148 #ifdef CONFIG_X86_IOPL_IOPERM 149 # define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY | \ 150 _TIF_IO_BITMAP) 151 #else 152 # define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY) 153 #endif 154 155 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW) 156 157 #define STACK_WARN (THREAD_SIZE/8) 158 159 /* 160 * macros/functions for gaining access to the thread information structure 161 * 162 * preempt_count needs to be 1 initially, until the scheduler is functional. 163 */ 164 #ifndef __ASSEMBLY__ 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 * GOOD_FRAME if within a frame 172 * BAD_STACK if placed across a frame boundary (or outside stack) 173 * NOT_STACK unable to determine (no frame pointers, etc) 174 * 175 * This function reads pointers from the stack and dereferences them. The 176 * pointers may not have their KMSAN shadow set up properly, which may result 177 * in false positive reports. Disable instrumentation to avoid those. 178 */ 179 __no_kmsan_checks 180 static inline int arch_within_stack_frames(const void * const stack, 181 const void * const stackend, 182 const void *obj, unsigned long len) 183 { 184 #if defined(CONFIG_FRAME_POINTER) 185 const void *frame = NULL; 186 const void *oldframe; 187 188 oldframe = __builtin_frame_address(1); 189 if (oldframe) 190 frame = __builtin_frame_address(2); 191 /* 192 * low ----------------------------------------------> high 193 * [saved bp][saved ip][args][local vars][saved bp][saved ip] 194 * ^----------------^ 195 * allow copies only within here 196 */ 197 while (stack <= frame && frame < stackend) { 198 /* 199 * If obj + len extends past the last frame, this 200 * check won't pass and the next frame will be 0, 201 * causing us to bail out and correctly report 202 * the copy as invalid. 203 */ 204 if (obj + len <= frame) 205 return obj >= oldframe + 2 * sizeof(void *) ? 206 GOOD_FRAME : BAD_STACK; 207 oldframe = frame; 208 frame = *(const void * const *)frame; 209 } 210 return BAD_STACK; 211 #else 212 return NOT_STACK; 213 #endif 214 } 215 216 #endif /* !__ASSEMBLY__ */ 217 218 /* 219 * Thread-synchronous status. 220 * 221 * This is different from the flags in that nobody else 222 * ever touches our thread-synchronous status, so we don't 223 * have to worry about atomic accesses. 224 */ 225 #define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/ 226 227 #ifndef __ASSEMBLY__ 228 #ifdef CONFIG_COMPAT 229 #define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */ 230 231 #define arch_set_restart_data(restart) \ 232 do { restart->arch_data = current_thread_info()->status; } while (0) 233 234 #endif 235 236 #ifdef CONFIG_X86_32 237 #define in_ia32_syscall() true 238 #else 239 #define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \ 240 current_thread_info()->status & TS_COMPAT) 241 #endif 242 243 extern void arch_setup_new_exec(void); 244 #define arch_setup_new_exec arch_setup_new_exec 245 #endif /* !__ASSEMBLY__ */ 246 247 #endif /* _ASM_X86_THREAD_INFO_H */ 248