diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/current.h | 2 | ||||
| -rw-r--r-- | arch/x86/include/asm/percpu.h | 26 | ||||
| -rw-r--r-- | arch/x86/include/asm/thread_info.h | 2 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 18 | ||||
| -rw-r--r-- | arch/x86/kernel/process_32.c | 3 | ||||
| -rw-r--r-- | arch/x86/kernel/process_64.c | 3 |
6 files changed, 35 insertions, 19 deletions
diff --git a/arch/x86/include/asm/current.h b/arch/x86/include/asm/current.h index c68c361697e..4d447b732d8 100644 --- a/arch/x86/include/asm/current.h +++ b/arch/x86/include/asm/current.h @@ -11,7 +11,7 @@ DECLARE_PER_CPU(struct task_struct *, current_task); static __always_inline struct task_struct *get_current(void) { - return percpu_read(current_task); + return percpu_read_stable(current_task); } #define current get_current() diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h index 103f1ddb0d8..04eacefcfd2 100644 --- a/arch/x86/include/asm/percpu.h +++ b/arch/x86/include/asm/percpu.h @@ -49,7 +49,7 @@ #define __percpu_arg(x) "%%"__stringify(__percpu_seg)":%P" #x #define __my_cpu_offset percpu_read(this_cpu_off) #else -#define __percpu_arg(x) "%" #x +#define __percpu_arg(x) "%P" #x #endif /* @@ -104,36 +104,48 @@ do { \ } \ } while (0) -#define percpu_from_op(op, var) \ +#define percpu_from_op(op, var, constraint) \ ({ \ typeof(var) ret__; \ switch (sizeof(var)) { \ case 1: \ asm(op "b "__percpu_arg(1)",%0" \ : "=q" (ret__) \ - : "m" (var)); \ + : constraint); \ break; \ case 2: \ asm(op "w "__percpu_arg(1)",%0" \ : "=r" (ret__) \ - : "m" (var)); \ + : constraint); \ break; \ case 4: \ asm(op "l "__percpu_arg(1)",%0" \ : "=r" (ret__) \ - : "m" (var)); \ + : constraint); \ break; \ case 8: \ asm(op "q "__percpu_arg(1)",%0" \ : "=r" (ret__) \ - : "m" (var)); \ + : constraint); \ break; \ default: __bad_percpu_size(); \ } \ ret__; \ }) -#define percpu_read(var) percpu_from_op("mov", per_cpu__##var) +/* + * percpu_read() makes gcc load the percpu variable every time it is + * accessed while percpu_read_stable() allows the value to be cached. + * percpu_read_stable() is more efficient and can be used if its value + * is guaranteed to be valid across cpus. The current users include + * get_current() and get_thread_info() both of which are actually + * per-thread variables implemented as per-cpu variables and thus + * stable for the duration of the respective task. + */ +#define percpu_read(var) percpu_from_op("mov", per_cpu__##var, \ + "m" (per_cpu__##var)) +#define percpu_read_stable(var) percpu_from_op("mov", per_cpu__##var, \ + "p" (&per_cpu__##var)) #define percpu_write(var, val) percpu_to_op("mov", per_cpu__##var, val) #define percpu_add(var, val) percpu_to_op("add", per_cpu__##var, val) #define percpu_sub(var, val) percpu_to_op("sub", per_cpu__##var, val) diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index 6f7786aea4f..d27d0a2fec4 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -214,7 +214,7 @@ DECLARE_PER_CPU(unsigned long, kernel_stack); static inline struct thread_info *current_thread_info(void) { struct thread_info *ti; - ti = (void *)(percpu_read(kernel_stack) + + ti = (void *)(percpu_read_stable(kernel_stack) + KERNEL_STACK_OFFSET - THREAD_SIZE); return ti; } diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 55a6abe4039..2055fc2b2e6 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -987,13 +987,21 @@ struct desc_ptr idt_descr = { NR_VECTORS * 16 - 1, (unsigned long) idt_table }; DEFINE_PER_CPU_FIRST(union irq_stack_union, irq_stack_union) __aligned(PAGE_SIZE); -DEFINE_PER_CPU(char *, irq_stack_ptr) = - init_per_cpu_var(irq_stack_union.irq_stack) + IRQ_STACK_SIZE - 64; +/* + * The following four percpu variables are hot. Align current_task to + * cacheline size such that all four fall in the same cacheline. + */ +DEFINE_PER_CPU(struct task_struct *, current_task) ____cacheline_aligned = + &init_task; +EXPORT_PER_CPU_SYMBOL(current_task); DEFINE_PER_CPU(unsigned long, kernel_stack) = (unsigned long)&init_thread_union - KERNEL_STACK_OFFSET + THREAD_SIZE; EXPORT_PER_CPU_SYMBOL(kernel_stack); +DEFINE_PER_CPU(char *, irq_stack_ptr) = + init_per_cpu_var(irq_stack_union.irq_stack) + IRQ_STACK_SIZE - 64; + DEFINE_PER_CPU(unsigned int, irq_count) = -1; /* @@ -1008,8 +1016,7 @@ static const unsigned int exception_stack_sizes[N_EXCEPTION_STACKS] = { }; static DEFINE_PER_CPU_PAGE_ALIGNED(char, exception_stacks - [(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ]) - __aligned(PAGE_SIZE); + [(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ]); /* May not be marked __init: used by software suspend */ void syscall_init(void) @@ -1042,6 +1049,9 @@ DEFINE_PER_CPU(struct orig_ist, orig_ist); #else /* CONFIG_X86_64 */ +DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task; +EXPORT_PER_CPU_SYMBOL(current_task); + #ifdef CONFIG_CC_STACKPROTECTOR DEFINE_PER_CPU_ALIGNED(struct stack_canary, stack_canary); #endif diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index a80eddd4165..4cf79567cda 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -61,9 +61,6 @@ asmlinkage void ret_from_fork(void) __asm__("ret_from_fork"); -DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task; -EXPORT_PER_CPU_SYMBOL(current_task); - /* * Return saved PC of a blocked thread. */ diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index a28279dbb07..ad535b68317 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -55,9 +55,6 @@ asmlinkage extern void ret_from_fork(void); -DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task; -EXPORT_PER_CPU_SYMBOL(current_task); - DEFINE_PER_CPU(unsigned long, old_rsp); static DEFINE_PER_CPU(unsigned char, is_idle); |