/* thread_info.h: low-level thread information * * Copyright (C) 2002 David Howells (dhowells@redhat.com) * - Incorporating suggestions made by Linus Torvalds and Dave Miller */ #ifndef _ASM_X86_THREAD_INFO_H #define _ASM_X86_THREAD_INFO_H #include #include #include #include /* * TOP_OF_KERNEL_STACK_PADDING is a number of unused bytes that we * reserve at the top of the kernel stack. We do it because of a nasty * 32-bit corner case. On x86_32, the hardware stack frame is * variable-length. Except for vm86 mode, struct pt_regs assumes a * maximum-length frame. If we enter from CPL 0, the top 8 bytes of * pt_regs don't actually exist. Ordinarily this doesn't matter, but it * does in at least one case: * * If we take an NMI early enough in SYSENTER, then we can end up with * pt_regs that extends above sp0. On the way out, in the espfix code, * we can read the saved SS value, but that value will be above sp0. * Without this offset, that can result in a page fault. (We are * careful that, in this case, the value we read doesn't matter.) * * In vm86 mode, the hardware frame is much longer still, so add 16 * bytes to make room for the real-mode segments. * * x86_64 has a fixed-length stack frame. */ #ifdef CONFIG_X86_32 # ifdef CONFIG_VM86 # define TOP_OF_KERNEL_STACK_PADDING 16 # else # define TOP_OF_KERNEL_STACK_PADDING 8 # endif #else # define TOP_OF_KERNEL_STACK_PADDING 0 #endif /* * low level task data that entry.S needs immediate access to * - this struct should fit entirely inside of one cache line * - this struct shares the supervisor stack pages */ #ifndef __ASSEMBLY__ struct task_struct; #include #include struct thread_info { struct task_struct *task; /* main task structure */ __u32 flags; /* low level flags */ __u32 status; /* thread synchronous flags */ __u32 cpu; /* current CPU */ }; #define INIT_THREAD_INFO(tsk) \ { \ .task = &tsk, \ .flags = 0, \ .cpu = 0, \ } #define init_thread_info (init_thread_union.thread_info) #define init_stack (init_thread_union.stack) #else /* !__ASSEMBLY__ */ #include #endif /* * thread information flags * - these are process state flags that various assembly files * may need to access * - pending work-to-be-done flags are in LSW * - other flags in MSW * Warning: layout of LSW is hardcoded in entry.S */ #define TIF_SYSCALL_TRACE 0 /* syscall trace active */ #define TIF_NOTIFY_RESUME 1 /* callback before returning to user */ #define TIF_SIGPENDING 2 /* signal pending */ #define TIF_NEED_RESCHED 3 /* rescheduling necessary */ #define TIF_SINGLESTEP 4 /* reenable singlestep on user return*/ #define TIF_SYSCALL_EMU 6 /* syscall emulation active */ #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */ #define TIF_SECCOMP 8 /* secure computing */ #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */ #define TIF_UPROBE 12 /* breakpointed or singlestepping */ #define TIF_NOTSC 16 /* TSC is not accessible in userland */ #define TIF_IA32 17 /* IA32 compatibility process */ #define TIF_FORK 18 /* ret_from_fork */ #define TIF_NOHZ 19 /* in adaptive nohz mode */ #define TIF_MEMDIE 20 /* is terminating due to OOM killer */ #define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */ #define TIF_IO_BITMAP 22 /* uses I/O bitmap */ #define TIF_FORCED_TF 24 /* true if TF in eflags artificially */ #define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */ #define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */ #define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */ #define TIF_ADDR32 29 /* 32-bit address space on 64 bits */ #define TIF_X32 30 /* 32-bit native x86-64 binary */ #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) #define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP) #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) #define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU) #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) #define _TIF_SECCOMP (1 << TIF_SECCOMP) #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY) #define _TIF_UPROBE (1 << TIF_UPROBE) #define _TIF_NOTSC (1 << TIF_NOTSC) #define _TIF_IA32 (1 << TIF_IA32) #define _TIF_FORK (1 << TIF_FORK) #define _TIF_NOHZ (1 << TIF_NOHZ) #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG) #define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP) #define _TIF_FORCED_TF (1 << TIF_FORCED_TF) #define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP) #define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES) #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT) #define _TIF_ADDR32 (1 << TIF_ADDR32) #define _TIF_X32 (1 << TIF_X32) /* * work to do in syscall_trace_enter(). Also includes TIF_NOHZ for * enter_from_user_mode() */ #define _TIF_WORK_SYSCALL_ENTRY \ (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \ _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \ _TIF_NOHZ) /* work to do on any return to user space */ #define _TIF_ALLWORK_MASK \ ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT | \ _TIF_NOHZ) /* flags to check in __switch_to() */ #define _TIF_WORK_CTXSW \ (_TIF_IO_BITMAP|_TIF_NOTSC|_TIF_BLOCKSTEP) #define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY) #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW) #define STACK_WARN (THREAD_SIZE/8) /* * macros/functions for gaining access to the thread information structure * * preempt_count needs to be 1 initially, until the scheduler is functional. */ #ifndef __ASSEMBLY__ static inline struct thread_info *current_thread_info(void) { return (struct thread_info *)(current_top_of_stack() - THREAD_SIZE); } static inline unsigned long current_stack_pointer(void) { unsigned long sp; #ifdef CONFIG_X86_64 asm("mov %%rsp,%0" : "=g" (sp)); #else asm("mov %%esp,%0" : "=g" (sp)); #endif return sp; } #else /* !__ASSEMBLY__ */ #ifdef CONFIG_X86_64 # define cpu_current_top_of_stack (cpu_tss + TSS_sp0) #endif /* * ASM operand which evaluates to a 'thread_info' address of * the current task, if it is known that "reg" is exactly "off" * bytes below the top of the stack currently. * * ( The kernel stack's size is known at build time, it is usually * 2 or 4 pages, and the bottom of the kernel stack contains * the thread_info structure. So to access the thread_info very * quickly from assembly code we can calculate down from the * top of the kernel stack to the bottom, using constant, * build-time calculations only. ) * * For example, to fetch the current thread_info->flags value into %eax * on x86-64 defconfig kernels, in syscall entry code where RSP is * currently at exactly SIZEOF_PTREGS bytes away from the top of the * stack: * * mov ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS), %eax * * will translate to: * * 8b 84 24 b8 c0 ff ff mov -0x3f48(%rsp), %eax * * which is below the current RSP by almost 16K. */ #define ASM_THREAD_INFO(field, reg, off) ((field)+(off)-THREAD_SIZE)(reg) #endif /* * Thread-synchronous status. * * This is different from the flags in that nobody else * ever touches our thread-synchronous status, so we don't * have to worry about atomic accesses. */ #define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/ #ifdef CONFIG_COMPAT #define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */ #endif #ifndef __ASSEMBLY__ static inline bool in_ia32_syscall(void) { #ifdef CONFIG_X86_32 return true; #endif #ifdef CONFIG_IA32_EMULATION if (current_thread_info()->status & TS_COMPAT) return true; #endif return false; } /* * Force syscall return via IRET by making it look as if there was * some work pending. IRET is our most capable (but slowest) syscall * return path, which is able to restore modified SS, CS and certain * EFLAGS values that other (fast) syscall return instructions * are not able to restore properly. */ #define force_iret() set_thread_flag(TIF_NOTIFY_RESUME) extern void arch_task_cache_init(void); extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); extern void arch_release_task_struct(struct task_struct *tsk); #endif /* !__ASSEMBLY__ */ #endif /* _ASM_X86_THREAD_INFO_H */