1 #ifndef __ASM_PREEMPT_H 2 #define __ASM_PREEMPT_H 3 4 #include <asm/rmwcc.h> 5 #include <asm/percpu.h> 6 #include <linux/thread_info.h> 7 8 DECLARE_PER_CPU(int, __preempt_count); 9 10 /* 11 * We mask the PREEMPT_NEED_RESCHED bit so as not to confuse all current users 12 * that think a non-zero value indicates we cannot preempt. 13 */ 14 static __always_inline int preempt_count(void) 15 { 16 return __this_cpu_read_4(__preempt_count) & ~PREEMPT_NEED_RESCHED; 17 } 18 19 static __always_inline void preempt_count_set(int pc) 20 { 21 __this_cpu_write_4(__preempt_count, pc); 22 } 23 24 /* 25 * must be macros to avoid header recursion hell 26 */ 27 #define task_preempt_count(p) \ 28 (task_thread_info(p)->saved_preempt_count & ~PREEMPT_NEED_RESCHED) 29 30 #define init_task_preempt_count(p) do { \ 31 task_thread_info(p)->saved_preempt_count = PREEMPT_DISABLED; \ 32 } while (0) 33 34 #define init_idle_preempt_count(p, cpu) do { \ 35 task_thread_info(p)->saved_preempt_count = PREEMPT_ENABLED; \ 36 per_cpu(__preempt_count, (cpu)) = PREEMPT_ENABLED; \ 37 } while (0) 38 39 /* 40 * We fold the NEED_RESCHED bit into the preempt count such that 41 * preempt_enable() can decrement and test for needing to reschedule with a 42 * single instruction. 43 * 44 * We invert the actual bit, so that when the decrement hits 0 we know we both 45 * need to resched (the bit is cleared) and can resched (no preempt count). 46 */ 47 48 static __always_inline void set_preempt_need_resched(void) 49 { 50 __this_cpu_and_4(__preempt_count, ~PREEMPT_NEED_RESCHED); 51 } 52 53 static __always_inline void clear_preempt_need_resched(void) 54 { 55 __this_cpu_or_4(__preempt_count, PREEMPT_NEED_RESCHED); 56 } 57 58 static __always_inline bool test_preempt_need_resched(void) 59 { 60 return !(__this_cpu_read_4(__preempt_count) & PREEMPT_NEED_RESCHED); 61 } 62 63 /* 64 * The various preempt_count add/sub methods 65 */ 66 67 static __always_inline void __preempt_count_add(int val) 68 { 69 __this_cpu_add_4(__preempt_count, val); 70 } 71 72 static __always_inline void __preempt_count_sub(int val) 73 { 74 __this_cpu_add_4(__preempt_count, -val); 75 } 76 77 static __always_inline bool __preempt_count_dec_and_test(void) 78 { 79 GEN_UNARY_RMWcc("decl", __preempt_count, __percpu_arg(0), "e"); 80 } 81 82 /* 83 * Returns true when we need to resched and can (barring IRQ state). 84 */ 85 static __always_inline bool should_resched(void) 86 { 87 return unlikely(!__this_cpu_read_4(__preempt_count)); 88 } 89 90 #ifdef CONFIG_PREEMPT 91 extern asmlinkage void ___preempt_schedule(void); 92 # define __preempt_schedule() asm ("call ___preempt_schedule") 93 extern asmlinkage void preempt_schedule(void); 94 # ifdef CONFIG_CONTEXT_TRACKING 95 extern asmlinkage void ___preempt_schedule_context(void); 96 # define __preempt_schedule_context() asm ("call ___preempt_schedule_context") 97 # endif 98 #endif 99 100 #endif /* __ASM_PREEMPT_H */ 101