Peter Zijlstra | c2daa3b | 2013-08-14 14:51:00 +0200 | [diff] [blame] | 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 | /* |
Peter Zijlstra | ba1f14f | 2013-11-28 14:26:41 +0100 | [diff] [blame] | 11 | * We use the PREEMPT_NEED_RESCHED bit as an inverted NEED_RESCHED such |
| 12 | * that a decrement hitting 0 means we can and should reschedule. |
| 13 | */ |
| 14 | #define PREEMPT_ENABLED (0 + PREEMPT_NEED_RESCHED) |
| 15 | |
| 16 | /* |
Peter Zijlstra | c2daa3b | 2013-08-14 14:51:00 +0200 | [diff] [blame] | 17 | * We mask the PREEMPT_NEED_RESCHED bit so as not to confuse all current users |
| 18 | * that think a non-zero value indicates we cannot preempt. |
| 19 | */ |
| 20 | static __always_inline int preempt_count(void) |
| 21 | { |
Christoph Lameter | b3ca1c1 | 2014-04-07 15:39:34 -0700 | [diff] [blame] | 22 | return raw_cpu_read_4(__preempt_count) & ~PREEMPT_NEED_RESCHED; |
Peter Zijlstra | c2daa3b | 2013-08-14 14:51:00 +0200 | [diff] [blame] | 23 | } |
| 24 | |
| 25 | static __always_inline void preempt_count_set(int pc) |
| 26 | { |
Christoph Lameter | b3ca1c1 | 2014-04-07 15:39:34 -0700 | [diff] [blame] | 27 | raw_cpu_write_4(__preempt_count, pc); |
Peter Zijlstra | c2daa3b | 2013-08-14 14:51:00 +0200 | [diff] [blame] | 28 | } |
| 29 | |
| 30 | /* |
| 31 | * must be macros to avoid header recursion hell |
| 32 | */ |
Peter Zijlstra | c2daa3b | 2013-08-14 14:51:00 +0200 | [diff] [blame] | 33 | #define init_task_preempt_count(p) do { \ |
| 34 | task_thread_info(p)->saved_preempt_count = PREEMPT_DISABLED; \ |
| 35 | } while (0) |
| 36 | |
| 37 | #define init_idle_preempt_count(p, cpu) do { \ |
| 38 | task_thread_info(p)->saved_preempt_count = PREEMPT_ENABLED; \ |
| 39 | per_cpu(__preempt_count, (cpu)) = PREEMPT_ENABLED; \ |
| 40 | } while (0) |
| 41 | |
| 42 | /* |
| 43 | * We fold the NEED_RESCHED bit into the preempt count such that |
| 44 | * preempt_enable() can decrement and test for needing to reschedule with a |
| 45 | * single instruction. |
| 46 | * |
| 47 | * We invert the actual bit, so that when the decrement hits 0 we know we both |
| 48 | * need to resched (the bit is cleared) and can resched (no preempt count). |
| 49 | */ |
| 50 | |
| 51 | static __always_inline void set_preempt_need_resched(void) |
| 52 | { |
Christoph Lameter | b3ca1c1 | 2014-04-07 15:39:34 -0700 | [diff] [blame] | 53 | raw_cpu_and_4(__preempt_count, ~PREEMPT_NEED_RESCHED); |
Peter Zijlstra | c2daa3b | 2013-08-14 14:51:00 +0200 | [diff] [blame] | 54 | } |
| 55 | |
| 56 | static __always_inline void clear_preempt_need_resched(void) |
| 57 | { |
Christoph Lameter | b3ca1c1 | 2014-04-07 15:39:34 -0700 | [diff] [blame] | 58 | raw_cpu_or_4(__preempt_count, PREEMPT_NEED_RESCHED); |
Peter Zijlstra | c2daa3b | 2013-08-14 14:51:00 +0200 | [diff] [blame] | 59 | } |
| 60 | |
| 61 | static __always_inline bool test_preempt_need_resched(void) |
| 62 | { |
Christoph Lameter | b3ca1c1 | 2014-04-07 15:39:34 -0700 | [diff] [blame] | 63 | return !(raw_cpu_read_4(__preempt_count) & PREEMPT_NEED_RESCHED); |
Peter Zijlstra | c2daa3b | 2013-08-14 14:51:00 +0200 | [diff] [blame] | 64 | } |
| 65 | |
| 66 | /* |
| 67 | * The various preempt_count add/sub methods |
| 68 | */ |
| 69 | |
| 70 | static __always_inline void __preempt_count_add(int val) |
| 71 | { |
Christoph Lameter | b3ca1c1 | 2014-04-07 15:39:34 -0700 | [diff] [blame] | 72 | raw_cpu_add_4(__preempt_count, val); |
Peter Zijlstra | c2daa3b | 2013-08-14 14:51:00 +0200 | [diff] [blame] | 73 | } |
| 74 | |
| 75 | static __always_inline void __preempt_count_sub(int val) |
| 76 | { |
Christoph Lameter | b3ca1c1 | 2014-04-07 15:39:34 -0700 | [diff] [blame] | 77 | raw_cpu_add_4(__preempt_count, -val); |
Peter Zijlstra | c2daa3b | 2013-08-14 14:51:00 +0200 | [diff] [blame] | 78 | } |
| 79 | |
Peter Zijlstra | ba1f14f | 2013-11-28 14:26:41 +0100 | [diff] [blame] | 80 | /* |
| 81 | * Because we keep PREEMPT_NEED_RESCHED set when we do _not_ need to reschedule |
| 82 | * a decrement which hits zero means we have no preempt_count and should |
| 83 | * reschedule. |
| 84 | */ |
Peter Zijlstra | c2daa3b | 2013-08-14 14:51:00 +0200 | [diff] [blame] | 85 | static __always_inline bool __preempt_count_dec_and_test(void) |
| 86 | { |
| 87 | GEN_UNARY_RMWcc("decl", __preempt_count, __percpu_arg(0), "e"); |
| 88 | } |
| 89 | |
| 90 | /* |
Peter Zijlstra | c2daa3b | 2013-08-14 14:51:00 +0200 | [diff] [blame] | 91 | * Returns true when we need to resched and can (barring IRQ state). |
| 92 | */ |
| 93 | static __always_inline bool should_resched(void) |
| 94 | { |
Christoph Lameter | b3ca1c1 | 2014-04-07 15:39:34 -0700 | [diff] [blame] | 95 | return unlikely(!raw_cpu_read_4(__preempt_count)); |
Peter Zijlstra | c2daa3b | 2013-08-14 14:51:00 +0200 | [diff] [blame] | 96 | } |
| 97 | |
Peter Zijlstra | 1a338ac | 2013-08-14 14:51:00 +0200 | [diff] [blame] | 98 | #ifdef CONFIG_PREEMPT |
| 99 | extern asmlinkage void ___preempt_schedule(void); |
| 100 | # define __preempt_schedule() asm ("call ___preempt_schedule") |
| 101 | extern asmlinkage void preempt_schedule(void); |
Frederic Weisbecker | 4eaca0a | 2015-06-04 17:39:08 +0200 | [diff] [blame] | 102 | extern asmlinkage void ___preempt_schedule_notrace(void); |
| 103 | # define __preempt_schedule_notrace() asm ("call ___preempt_schedule_notrace") |
| 104 | extern asmlinkage void preempt_schedule_notrace(void); |
Peter Zijlstra | 1a338ac | 2013-08-14 14:51:00 +0200 | [diff] [blame] | 105 | #endif |
| 106 | |
Peter Zijlstra | c2daa3b | 2013-08-14 14:51:00 +0200 | [diff] [blame] | 107 | #endif /* __ASM_PREEMPT_H */ |