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__ 51struct task_struct; 52#include <asm/cpufeature.h> 53#include <linux/atomic.h> 54 55struct thread_info { 56 unsigned long flags; /* low level flags */ 57}; 58 59#define INIT_THREAD_INFO(tsk) \ 60{ \ 61 .flags = 0, \ 62} 63 64#define init_stack (init_thread_union.stack) 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_SYSCALL_EMU 6 /* syscall emulation active */ 83#define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */ 84#define TIF_SECCOMP 8 /* secure computing */ 85#define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */ 86#define TIF_UPROBE 12 /* breakpointed or singlestepping */ 87#define TIF_PATCH_PENDING 13 /* pending live patching update */ 88#define TIF_NOCPUID 15 /* CPUID is not accessible in userland */ 89#define TIF_NOTSC 16 /* TSC is not accessible in userland */ 90#define TIF_IA32 17 /* IA32 compatibility process */ 91#define TIF_NOHZ 19 /* in adaptive nohz mode */ 92#define TIF_MEMDIE 20 /* is terminating due to OOM killer */ 93#define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */ 94#define TIF_IO_BITMAP 22 /* uses I/O bitmap */ 95#define TIF_FORCED_TF 24 /* true if TF in eflags artificially */ 96#define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */ 97#define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */ 98#define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */ 99#define TIF_ADDR32 29 /* 32-bit address space on 64 bits */ 100#define TIF_X32 30 /* 32-bit native x86-64 binary */ 101 102#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) 103#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) 104#define _TIF_SIGPENDING (1 << TIF_SIGPENDING) 105#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) 106#define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP) 107#define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU) 108#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) 109#define _TIF_SECCOMP (1 << TIF_SECCOMP) 110#define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY) 111#define _TIF_UPROBE (1 << TIF_UPROBE) 112#define _TIF_PATCH_PENDING (1 << TIF_PATCH_PENDING) 113#define _TIF_NOCPUID (1 << TIF_NOCPUID) 114#define _TIF_NOTSC (1 << TIF_NOTSC) 115#define _TIF_IA32 (1 << TIF_IA32) 116#define _TIF_NOHZ (1 << TIF_NOHZ) 117#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG) 118#define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP) 119#define _TIF_FORCED_TF (1 << TIF_FORCED_TF) 120#define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP) 121#define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES) 122#define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT) 123#define _TIF_ADDR32 (1 << TIF_ADDR32) 124#define _TIF_X32 (1 << TIF_X32) 125 126/* 127 * work to do in syscall_trace_enter(). Also includes TIF_NOHZ for 128 * enter_from_user_mode() 129 */ 130#define _TIF_WORK_SYSCALL_ENTRY \ 131 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \ 132 _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \ 133 _TIF_NOHZ) 134 135/* work to do on any return to user space */ 136#define _TIF_ALLWORK_MASK \ 137 (_TIF_SYSCALL_TRACE | _TIF_NOTIFY_RESUME | _TIF_SIGPENDING | \ 138 _TIF_NEED_RESCHED | _TIF_SINGLESTEP | _TIF_SYSCALL_EMU | \ 139 _TIF_SYSCALL_AUDIT | _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE | \ 140 _TIF_PATCH_PENDING | _TIF_NOHZ | _TIF_SYSCALL_TRACEPOINT) 141 142/* flags to check in __switch_to() */ 143#define _TIF_WORK_CTXSW \ 144 (_TIF_IO_BITMAP|_TIF_NOCPUID|_TIF_NOTSC|_TIF_BLOCKSTEP) 145 146#define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY) 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 158static inline unsigned long current_stack_pointer(void) 159{ 160 unsigned long sp; 161#ifdef CONFIG_X86_64 162 asm("mov %%rsp,%0" : "=g" (sp)); 163#else 164 asm("mov %%esp,%0" : "=g" (sp)); 165#endif 166 return sp; 167} 168 169/* 170 * Walks up the stack frames to make sure that the specified object is 171 * entirely contained by a single stack frame. 172 * 173 * Returns: 174 * GOOD_FRAME if within a frame 175 * BAD_STACK if placed across a frame boundary (or outside stack) 176 * NOT_STACK unable to determine (no frame pointers, etc) 177 */ 178static inline int arch_within_stack_frames(const void * const stack, 179 const void * const stackend, 180 const void *obj, unsigned long len) 181{ 182#if defined(CONFIG_FRAME_POINTER) 183 const void *frame = NULL; 184 const void *oldframe; 185 186 oldframe = __builtin_frame_address(1); 187 if (oldframe) 188 frame = __builtin_frame_address(2); 189 /* 190 * low ----------------------------------------------> high 191 * [saved bp][saved ip][args][local vars][saved bp][saved ip] 192 * ^----------------^ 193 * allow copies only within here 194 */ 195 while (stack <= frame && frame < stackend) { 196 /* 197 * If obj + len extends past the last frame, this 198 * check won't pass and the next frame will be 0, 199 * causing us to bail out and correctly report 200 * the copy as invalid. 201 */ 202 if (obj + len <= frame) 203 return obj >= oldframe + 2 * sizeof(void *) ? 204 GOOD_FRAME : BAD_STACK; 205 oldframe = frame; 206 frame = *(const void * const *)frame; 207 } 208 return BAD_STACK; 209#else 210 return NOT_STACK; 211#endif 212} 213 214#else /* !__ASSEMBLY__ */ 215 216#ifdef CONFIG_X86_64 217# define cpu_current_top_of_stack (cpu_tss + TSS_sp0) 218#endif 219 220#endif 221 222#ifdef CONFIG_COMPAT 223#define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */ 224#endif 225#ifndef __ASSEMBLY__ 226 227#ifdef CONFIG_X86_32 228#define in_ia32_syscall() true 229#else 230#define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \ 231 current->thread.status & TS_COMPAT) 232#endif 233 234/* 235 * Force syscall return via IRET by making it look as if there was 236 * some work pending. IRET is our most capable (but slowest) syscall 237 * return path, which is able to restore modified SS, CS and certain 238 * EFLAGS values that other (fast) syscall return instructions 239 * are not able to restore properly. 240 */ 241#define force_iret() set_thread_flag(TIF_NOTIFY_RESUME) 242 243extern void arch_task_cache_init(void); 244extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); 245extern void arch_release_task_struct(struct task_struct *tsk); 246extern void arch_setup_new_exec(void); 247#define arch_setup_new_exec arch_setup_new_exec 248#endif /* !__ASSEMBLY__ */ 249 250#endif /* _ASM_X86_THREAD_INFO_H */ 251