--- zzzz-none-000/linux-3.10.107/arch/x86/include/asm/thread_info.h 2017-06-27 09:49:32.000000000 +0000 +++ scorpion-7490-727/linux-3.10.107/arch/x86/include/asm/thread_info.h 2021-02-04 17:41:59.000000000 +0000 @@ -9,36 +9,55 @@ #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; -struct exec_domain; #include #include struct thread_info { struct task_struct *task; /* main task structure */ - struct exec_domain *exec_domain; /* execution domain */ __u32 flags; /* low level flags */ __u32 status; /* thread synchronous flags */ __u32 cpu; /* current CPU */ - int preempt_count; /* 0 => preemptable, - <0 => BUG */ mm_segment_t addr_limit; - struct restart_block restart_block; - void __user *sysenter_return; -#ifdef CONFIG_X86_32 - unsigned long previous_esp; /* ESP of the previous stack in - case of nested (IRQ) stacks - */ - __u8 supervisor_stack[0]; -#endif unsigned int sig_on_uaccess_error:1; unsigned int uaccess_err:1; /* uaccess failed */ }; @@ -46,14 +65,9 @@ #define INIT_THREAD_INFO(tsk) \ { \ .task = &tsk, \ - .exec_domain = &default_exec_domain, \ .flags = 0, \ .cpu = 0, \ - .preempt_count = INIT_PREEMPT_COUNT, \ .addr_limit = KERNEL_DS, \ - .restart_block = { \ - .fn = do_no_restart_syscall, \ - }, \ } #define init_thread_info (init_thread_union.thread_info) @@ -81,7 +95,6 @@ #define TIF_SYSCALL_EMU 6 /* syscall emulation active */ #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */ #define TIF_SECCOMP 8 /* secure computing */ -#define TIF_MCE_NOTIFY 10 /* notify userspace of an MCE */ #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 */ @@ -89,7 +102,7 @@ #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_DEBUG 21 /* uses debug registers */ +#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 */ @@ -106,14 +119,13 @@ #define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU) #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) #define _TIF_SECCOMP (1 << TIF_SECCOMP) -#define _TIF_MCE_NOTIFY (1 << TIF_MCE_NOTIFY) #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_DEBUG (1 << TIF_DEBUG) +#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) @@ -128,39 +140,20 @@ _TIF_SECCOMP | _TIF_SINGLESTEP | _TIF_SYSCALL_TRACEPOINT | \ _TIF_NOHZ) -/* work to do in syscall_trace_leave() */ -#define _TIF_WORK_SYSCALL_EXIT \ - (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SINGLESTEP | \ - _TIF_SYSCALL_TRACEPOINT | _TIF_NOHZ) - -/* work to do on interrupt/exception return */ -#define _TIF_WORK_MASK \ - (0x0000FFFF & \ - ~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT| \ - _TIF_SINGLESTEP|_TIF_SECCOMP|_TIF_SYSCALL_EMU)) - /* work to do on any return to user space */ #define _TIF_ALLWORK_MASK \ ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT | \ _TIF_NOHZ) -/* Only used for 64 bit */ -#define _TIF_DO_NOTIFY_MASK \ - (_TIF_SIGPENDING | _TIF_MCE_NOTIFY | _TIF_NOTIFY_RESUME | \ - _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE) - /* 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|_TIF_DEBUG) - -#define PREEMPT_ACTIVE 0x10000000 +#define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW) -#ifdef CONFIG_X86_32 +#define STACK_WARN (THREAD_SIZE/8) -#define STACK_WARN (THREAD_SIZE/8) /* * macros/functions for gaining access to the thread information structure * @@ -168,67 +161,62 @@ */ #ifndef __ASSEMBLY__ - -/* how to get the current stack pointer from C */ -register unsigned long current_stack_pointer asm("esp") __used; - -/* how to get the thread information struct from C */ static inline struct thread_info *current_thread_info(void) { - return (struct thread_info *) - (current_stack_pointer & ~(THREAD_SIZE - 1)); + return (struct thread_info *)(current_top_of_stack() - THREAD_SIZE); } -#else /* !__ASSEMBLY__ */ - -/* how to get the thread information struct from ASM */ -#define GET_THREAD_INFO(reg) \ - movl $-THREAD_SIZE, reg; \ - andl %esp, reg - -/* use this one if reg already contains %esp */ -#define GET_THREAD_INFO_WITH_ESP(reg) \ - andl $-THREAD_SIZE, reg - -#endif - -#else /* X86_32 */ - -#include -#define KERNEL_STACK_OFFSET (5*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__ -DECLARE_PER_CPU(unsigned long, kernel_stack); - -static inline struct thread_info *current_thread_info(void) +static inline unsigned long current_stack_pointer(void) { - struct thread_info *ti; - ti = (void *)(this_cpu_read_stable(kernel_stack) + - KERNEL_STACK_OFFSET - THREAD_SIZE); - return ti; + 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__ */ -/* how to get the thread information struct from ASM */ +#ifdef CONFIG_X86_64 +# define cpu_current_top_of_stack (cpu_tss + TSS_sp0) +#endif + +/* Load thread_info address into "reg" */ #define GET_THREAD_INFO(reg) \ - movq PER_CPU_VAR(kernel_stack),reg ; \ - subq $(THREAD_SIZE-KERNEL_STACK_OFFSET),reg + _ASM_MOV PER_CPU_VAR(cpu_current_top_of_stack),reg ; \ + _ASM_SUB $(THREAD_SIZE),reg ; /* - * Same if PER_CPU_VAR(kernel_stack) is, perhaps with some offset, already in - * a certain register (to be used in assembler memory operands). + * 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 THREAD_INFO(reg, off) KERNEL_STACK_OFFSET+(off)-THREAD_SIZE(reg) +#define ASM_THREAD_INFO(field, reg, off) ((field)+(off)-THREAD_SIZE)(reg) #endif -#endif /* !X86_32 */ - /* * Thread-synchronous status. * @@ -237,8 +225,6 @@ * have to worry about atomic accesses. */ #define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/ -#define TS_POLLING 0x0004 /* idle task polling need_resched, - skip sending interrupt */ #define TS_RESTORE_SIGMASK 0x0008 /* restore signal mask in do_signal() */ #ifndef __ASSEMBLY__ @@ -277,6 +263,16 @@ #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) + #endif /* !__ASSEMBLY__ */ #ifndef __ASSEMBLY__