From 15f4eae70d365bba26854c90b6002aaabb18c8aa Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Tue, 13 Sep 2016 14:29:25 -0700 Subject: [PATCH] x86: Move thread_info into task_struct Now that most of the thread_info users have been cleaned up, this is straightforward. Most of this code was written by Linus. Originally-from: Linus Torvalds Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jann Horn Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/a50eab40abeaec9cb9a9e3cbdeafd32190206654.1473801993.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/Kconfig | 1 + arch/x86/entry/entry_64.S | 7 +++-- arch/x86/include/asm/thread_info.h | 46 ------------------------------ arch/x86/kernel/asm-offsets.c | 4 +-- arch/x86/kernel/irq_64.c | 3 +- arch/x86/kernel/process.c | 6 ++-- 6 files changed, 10 insertions(+), 57 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 4c3972847c2a..2a83bc8b24c6 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -157,6 +157,7 @@ config X86 select SPARSE_IRQ select SRCU select SYSCTL_EXCEPTION_TRACE + select THREAD_INFO_IN_TASK select USER_STACKTRACE_SUPPORT select VIRT_TO_BUS select X86_DEV_DMA_OPS if X86_64 diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index e7fba58f4d9c..2b46384b4a4f 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -179,7 +179,8 @@ GLOBAL(entry_SYSCALL_64_after_swapgs) * If we need to do entry work or if we guess we'll need to do * exit work, go straight to the slow path. */ - testl $_TIF_WORK_SYSCALL_ENTRY|_TIF_ALLWORK_MASK, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) + movq PER_CPU_VAR(current_task), %r11 + testl $_TIF_WORK_SYSCALL_ENTRY|_TIF_ALLWORK_MASK, TASK_TI_flags(%r11) jnz entry_SYSCALL64_slow_path entry_SYSCALL_64_fastpath: @@ -217,7 +218,8 @@ entry_SYSCALL_64_fastpath: */ DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF - testl $_TIF_ALLWORK_MASK, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) + movq PER_CPU_VAR(current_task), %r11 + testl $_TIF_ALLWORK_MASK, TASK_TI_flags(%r11) jnz 1f LOCKDEP_SYS_EXIT @@ -370,6 +372,7 @@ END(ptregs_\func) /* * %rdi: prev task * %rsi: next task + * rsi: task we're switching to */ ENTRY(__switch_to_asm) /* diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index c9dcfe7c7e4b..2aaca53c0974 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -52,20 +52,6 @@ struct task_struct; #include #include -struct thread_info { - struct task_struct *task; /* main task structure */ - __u32 flags; /* low level 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__ */ @@ -157,11 +143,6 @@ struct thread_info { */ #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; @@ -223,33 +204,6 @@ static inline int arch_within_stack_frames(const void * const stack, # 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 #ifdef CONFIG_COMPAT diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c index add5f90b93d4..c62e015b126c 100644 --- a/arch/x86/kernel/asm-offsets.c +++ b/arch/x86/kernel/asm-offsets.c @@ -35,9 +35,7 @@ void common(void) { #endif BLANK(); - OFFSET(TI_flags, thread_info, flags); - - BLANK(); + OFFSET(TASK_TI_flags, task_struct, thread_info.flags); OFFSET(TASK_addr_limit, task_struct, thread.addr_limit); BLANK(); diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c index 4a7903714065..9ebd0b0e73d9 100644 --- a/arch/x86/kernel/irq_64.c +++ b/arch/x86/kernel/irq_64.c @@ -40,8 +40,7 @@ static inline void stack_overflow_check(struct pt_regs *regs) if (user_mode(regs)) return; - if (regs->sp >= curbase + sizeof(struct thread_info) + - sizeof(struct pt_regs) + STACK_TOP_MARGIN && + if (regs->sp >= curbase + sizeof(struct pt_regs) + STACK_TOP_MARGIN && regs->sp <= curbase + THREAD_SIZE) return; diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index c1fa790c81cd..0b9ed8ec5226 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -549,9 +549,7 @@ unsigned long get_wchan(struct task_struct *p) * PADDING * ----------- top = topmax - TOP_OF_KERNEL_STACK_PADDING * stack - * ----------- bottom = start + sizeof(thread_info) - * thread_info - * ----------- start + * ----------- bottom = start * * The tasks stack pointer points at the location where the * framepointer is stored. The data on the stack is: @@ -562,7 +560,7 @@ unsigned long get_wchan(struct task_struct *p) */ top = start + THREAD_SIZE - TOP_OF_KERNEL_STACK_PADDING; top -= 2 * sizeof(unsigned long); - bottom = start + sizeof(struct thread_info); + bottom = start; sp = READ_ONCE(p->thread.sp); if (sp < bottom || sp > top) -- 2.20.1