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__ 52struct task_struct; 53#include <asm/cpufeature.h> 54#include <linux/atomic.h> 55 56struct thread_info { 57 unsigned long flags; /* low level flags */ 58 u32 status; /* thread synchronous flags */ 59}; 60 61#define INIT_THREAD_INFO(tsk) \ 62{ \ 63 .flags = 0, \ 64} 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 */ 77#define TIF_SYSCALL_TRACE 0 /* syscall trace active */ 78#define TIF_NOTIFY_RESUME 1 /* callback before returning to user */ 79#define TIF_SIGPENDING 2 /* signal pending */ 80#define TIF_NEED_RESCHED 3 /* rescheduling necessary */ 81#define TIF_SINGLESTEP 4 /* reenable singlestep on user return*/ 82#define TIF_SSBD 5 /* Speculative store bypass disable */ 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_SPEC_IB 9 /* Indirect branch speculation mitigation */ 87#define TIF_SPEC_FORCE_UPDATE 10 /* Force speculation MSR update in context switch */ 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_IA32 17 /* IA32 compatibility process */ 95#define TIF_SLD 18 /* Restore split lock detection on context switch */ 96#define TIF_NOHZ 19 /* in adaptive nohz mode */ 97#define TIF_MEMDIE 20 /* is terminating due to OOM killer */ 98#define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */ 99#define TIF_IO_BITMAP 22 /* uses I/O bitmap */ 100#define TIF_FORCED_TF 24 /* true if TF in eflags artificially */ 101#define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */ 102#define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */ 103#define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */ 104#define TIF_ADDR32 29 /* 32-bit address space on 64 bits */ 105#define TIF_X32 30 /* 32-bit native x86-64 binary */ 106#define TIF_FSCHECK 31 /* Check FS is USER_DS on return */ 107 108#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) 109#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) 110#define _TIF_SIGPENDING (1 << TIF_SIGPENDING) 111#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) 112#define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP) 113#define _TIF_SSBD (1 << TIF_SSBD) 114#define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU) 115#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) 116#define _TIF_SECCOMP (1 << TIF_SECCOMP) 117#define _TIF_SPEC_IB (1 << TIF_SPEC_IB) 118#define _TIF_SPEC_FORCE_UPDATE (1 << TIF_SPEC_FORCE_UPDATE) 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_IA32 (1 << TIF_IA32) 126#define _TIF_SLD (1 << TIF_SLD) 127#define _TIF_NOHZ (1 << TIF_NOHZ) 128#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG) 129#define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP) 130#define _TIF_FORCED_TF (1 << TIF_FORCED_TF) 131#define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP) 132#define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES) 133#define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT) 134#define _TIF_ADDR32 (1 << TIF_ADDR32) 135#define _TIF_X32 (1 << TIF_X32) 136#define _TIF_FSCHECK (1 << TIF_FSCHECK) 137 138/* 139 * work to do in syscall_trace_enter(). Also includes TIF_NOHZ for 140 * enter_from_user_mode() 141 */ 142#define _TIF_WORK_SYSCALL_ENTRY \ 143 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \ 144 _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \ 145 _TIF_NOHZ) 146 147/* work to do on any return to user space */ 148#define _TIF_ALLWORK_MASK \ 149 (_TIF_SYSCALL_TRACE | _TIF_NOTIFY_RESUME | _TIF_SIGPENDING | \ 150 _TIF_NEED_RESCHED | _TIF_SINGLESTEP | _TIF_SYSCALL_EMU | \ 151 _TIF_SYSCALL_AUDIT | _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE | \ 152 _TIF_PATCH_PENDING | _TIF_NOHZ | _TIF_SYSCALL_TRACEPOINT | \ 153 _TIF_FSCHECK) 154 155/* flags to check in __switch_to() */ 156#define _TIF_WORK_CTXSW_BASE \ 157 (_TIF_IO_BITMAP|_TIF_NOCPUID|_TIF_NOTSC|_TIF_BLOCKSTEP| \ 158 _TIF_SSBD | _TIF_SPEC_FORCE_UPDATE | _TIF_SLD) 159 160/* 161 * Avoid calls to __switch_to_xtra() on UP as STIBP is not evaluated. 162 */ 163#ifdef CONFIG_SMP 164# define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE | _TIF_SPEC_IB) 165#else 166# define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE) 167#endif 168 169#define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY) 170#define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW) 171 172#define STACK_WARN (THREAD_SIZE/8) 173 174/* 175 * macros/functions for gaining access to the thread information structure 176 * 177 * preempt_count needs to be 1 initially, until the scheduler is functional. 178 */ 179#ifndef __ASSEMBLY__ 180 181/* 182 * Walks up the stack frames to make sure that the specified object is 183 * entirely contained by a single stack frame. 184 * 185 * Returns: 186 * GOOD_FRAME if within a frame 187 * BAD_STACK if placed across a frame boundary (or outside stack) 188 * NOT_STACK unable to determine (no frame pointers, etc) 189 */ 190static inline int arch_within_stack_frames(const void * const stack, 191 const void * const stackend, 192 const void *obj, unsigned long len) 193{ 194#if defined(CONFIG_FRAME_POINTER) 195 const void *frame = NULL; 196 const void *oldframe; 197 198 oldframe = __builtin_frame_address(1); 199 if (oldframe) 200 frame = __builtin_frame_address(2); 201 /* 202 * low ----------------------------------------------> high 203 * [saved bp][saved ip][args][local vars][saved bp][saved ip] 204 * ^----------------^ 205 * allow copies only within here 206 */ 207 while (stack <= frame && frame < stackend) { 208 /* 209 * If obj + len extends past the last frame, this 210 * check won't pass and the next frame will be 0, 211 * causing us to bail out and correctly report 212 * the copy as invalid. 213 */ 214 if (obj + len <= frame) 215 return obj >= oldframe + 2 * sizeof(void *) ? 216 GOOD_FRAME : BAD_STACK; 217 oldframe = frame; 218 frame = *(const void * const *)frame; 219 } 220 return BAD_STACK; 221#else 222 return NOT_STACK; 223#endif 224} 225 226#else /* !__ASSEMBLY__ */ 227 228#ifdef CONFIG_X86_64 229# define cpu_current_top_of_stack (cpu_tss_rw + TSS_sp1) 230#endif 231 232#endif 233 234#ifdef CONFIG_COMPAT 235#define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */ 236#endif 237#ifndef __ASSEMBLY__ 238 239#ifdef CONFIG_X86_32 240#define in_ia32_syscall() true 241#else 242#define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \ 243 current_thread_info()->status & TS_COMPAT) 244#endif 245 246/* 247 * Force syscall return via IRET by making it look as if there was 248 * some work pending. IRET is our most capable (but slowest) syscall 249 * return path, which is able to restore modified SS, CS and certain 250 * EFLAGS values that other (fast) syscall return instructions 251 * are not able to restore properly. 252 */ 253#define force_iret() set_thread_flag(TIF_NOTIFY_RESUME) 254 255extern void arch_task_cache_init(void); 256extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); 257extern void arch_release_task_struct(struct task_struct *tsk); 258extern void arch_setup_new_exec(void); 259#define arch_setup_new_exec arch_setup_new_exec 260#endif /* !__ASSEMBLY__ */ 261 262#endif /* _ASM_X86_THREAD_INFO_H */ 263