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 unsigned long syscall_work; /* SYSCALL_WORK_ flags */ 59 u32 status; /* thread synchronous flags */ 60 #ifdef CONFIG_SMP 61 u32 cpu; /* current CPU */ 62 #endif 63 }; 64 65 #define INIT_THREAD_INFO(tsk) \ 66 { \ 67 .flags = 0, \ 68 } 69 70 #else /* !__ASSEMBLY__ */ 71 72 #include <asm/asm-offsets.h> 73 74 #endif 75 76 /* 77 * thread information flags 78 * - these are process state flags that various assembly files 79 * may need to access 80 */ 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_SSBD 5 /* Speculative store bypass disable */ 86 #define TIF_SPEC_IB 9 /* Indirect branch speculation mitigation */ 87 #define TIF_SPEC_L1D_FLUSH 10 /* Flush L1D on mm switches (processes) */ 88 #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */ 89 #define TIF_UPROBE 12 /* breakpointed or singlestepping */ 90 #define TIF_PATCH_PENDING 13 /* pending live patching update */ 91 #define TIF_NEED_FPU_LOAD 14 /* load FPU on return to userspace */ 92 #define TIF_NOCPUID 15 /* CPUID is not accessible in userland */ 93 #define TIF_NOTSC 16 /* TSC is not accessible in userland */ 94 #define TIF_NOTIFY_SIGNAL 17 /* signal notifications exist */ 95 #define TIF_MEMDIE 20 /* is terminating due to OOM killer */ 96 #define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */ 97 #define TIF_IO_BITMAP 22 /* uses I/O bitmap */ 98 #define TIF_SPEC_FORCE_UPDATE 23 /* Force speculation MSR update in context switch */ 99 #define TIF_FORCED_TF 24 /* true if TF in eflags artificially */ 100 #define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */ 101 #define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */ 102 #define TIF_ADDR32 29 /* 32-bit address space on 64 bits */ 103 104 #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) 105 #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) 106 #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) 107 #define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP) 108 #define _TIF_SSBD (1 << TIF_SSBD) 109 #define _TIF_SPEC_IB (1 << TIF_SPEC_IB) 110 #define _TIF_SPEC_L1D_FLUSH (1 << TIF_SPEC_L1D_FLUSH) 111 #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY) 112 #define _TIF_UPROBE (1 << TIF_UPROBE) 113 #define _TIF_PATCH_PENDING (1 << TIF_PATCH_PENDING) 114 #define _TIF_NEED_FPU_LOAD (1 << TIF_NEED_FPU_LOAD) 115 #define _TIF_NOCPUID (1 << TIF_NOCPUID) 116 #define _TIF_NOTSC (1 << TIF_NOTSC) 117 #define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL) 118 #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG) 119 #define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP) 120 #define _TIF_SPEC_FORCE_UPDATE (1 << TIF_SPEC_FORCE_UPDATE) 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_ADDR32 (1 << TIF_ADDR32) 125 126 /* flags to check in __switch_to() */ 127 #define _TIF_WORK_CTXSW_BASE \ 128 (_TIF_NOCPUID | _TIF_NOTSC | _TIF_BLOCKSTEP | \ 129 _TIF_SSBD | _TIF_SPEC_FORCE_UPDATE) 130 131 /* 132 * Avoid calls to __switch_to_xtra() on UP as STIBP is not evaluated. 133 */ 134 #ifdef CONFIG_SMP 135 # define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE | _TIF_SPEC_IB) 136 #else 137 # define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE) 138 #endif 139 140 #ifdef CONFIG_X86_IOPL_IOPERM 141 # define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY | \ 142 _TIF_IO_BITMAP) 143 #else 144 # define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY) 145 #endif 146 147 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW) 148 149 #define STACK_WARN (THREAD_SIZE/8) 150 151 /* 152 * macros/functions for gaining access to the thread information structure 153 * 154 * preempt_count needs to be 1 initially, until the scheduler is functional. 155 */ 156 #ifndef __ASSEMBLY__ 157 158 /* 159 * Walks up the stack frames to make sure that the specified object is 160 * entirely contained by a single stack frame. 161 * 162 * Returns: 163 * GOOD_FRAME if within a frame 164 * BAD_STACK if placed across a frame boundary (or outside stack) 165 * NOT_STACK unable to determine (no frame pointers, etc) 166 * 167 * This function reads pointers from the stack and dereferences them. The 168 * pointers may not have their KMSAN shadow set up properly, which may result 169 * in false positive reports. Disable instrumentation to avoid those. 170 */ 171 __no_kmsan_checks 172 static inline int arch_within_stack_frames(const void * const stack, 173 const void * const stackend, 174 const void *obj, unsigned long len) 175 { 176 #if defined(CONFIG_FRAME_POINTER) 177 const void *frame = NULL; 178 const void *oldframe; 179 180 oldframe = __builtin_frame_address(1); 181 if (oldframe) 182 frame = __builtin_frame_address(2); 183 /* 184 * low ----------------------------------------------> high 185 * [saved bp][saved ip][args][local vars][saved bp][saved ip] 186 * ^----------------^ 187 * allow copies only within here 188 */ 189 while (stack <= frame && frame < stackend) { 190 /* 191 * If obj + len extends past the last frame, this 192 * check won't pass and the next frame will be 0, 193 * causing us to bail out and correctly report 194 * the copy as invalid. 195 */ 196 if (obj + len <= frame) 197 return obj >= oldframe + 2 * sizeof(void *) ? 198 GOOD_FRAME : BAD_STACK; 199 oldframe = frame; 200 frame = *(const void * const *)frame; 201 } 202 return BAD_STACK; 203 #else 204 return NOT_STACK; 205 #endif 206 } 207 208 #endif /* !__ASSEMBLY__ */ 209 210 /* 211 * Thread-synchronous status. 212 * 213 * This is different from the flags in that nobody else 214 * ever touches our thread-synchronous status, so we don't 215 * have to worry about atomic accesses. 216 */ 217 #define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/ 218 219 #ifndef __ASSEMBLY__ 220 #ifdef CONFIG_COMPAT 221 #define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */ 222 223 #define arch_set_restart_data(restart) \ 224 do { restart->arch_data = current_thread_info()->status; } while (0) 225 226 #endif 227 228 #ifdef CONFIG_X86_32 229 #define in_ia32_syscall() true 230 #else 231 #define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \ 232 current_thread_info()->status & TS_COMPAT) 233 #endif 234 235 extern void arch_setup_new_exec(void); 236 #define arch_setup_new_exec arch_setup_new_exec 237 #endif /* !__ASSEMBLY__ */ 238 239 #endif /* _ASM_X86_THREAD_INFO_H */ 240