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bc83cccc PA |
1 | #ifndef _ASM_X86_MWAIT_H |
2 | #define _ASM_X86_MWAIT_H | |
3 | ||
16824255 PZ |
4 | #include <linux/sched.h> |
5 | ||
cd4d09ec BP |
6 | #include <asm/cpufeature.h> |
7 | ||
bc83cccc PA |
8 | #define MWAIT_SUBSTATE_MASK 0xf |
9 | #define MWAIT_CSTATE_MASK 0xf | |
10 | #define MWAIT_SUBSTATE_SIZE 4 | |
e022e7eb LB |
11 | #define MWAIT_HINT2CSTATE(hint) (((hint) >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) |
12 | #define MWAIT_HINT2SUBSTATE(hint) ((hint) & MWAIT_CSTATE_MASK) | |
bc83cccc PA |
13 | |
14 | #define CPUID_MWAIT_LEAF 5 | |
15 | #define CPUID5_ECX_EXTENSIONS_SUPPORTED 0x1 | |
16 | #define CPUID5_ECX_INTERRUPT_BREAK 0x2 | |
17 | ||
18 | #define MWAIT_ECX_INTERRUPT_BREAK 0x1 | |
f9675674 HR |
19 | #define MWAITX_ECX_TIMER_ENABLE BIT(1) |
20 | #define MWAITX_MAX_LOOPS ((u32)-1) | |
21 | #define MWAITX_DISABLE_CSTATES 0xf | |
bc83cccc | 22 | |
16824255 PZ |
23 | static inline void __monitor(const void *eax, unsigned long ecx, |
24 | unsigned long edx) | |
25 | { | |
26 | /* "monitor %eax, %ecx, %edx;" */ | |
27 | asm volatile(".byte 0x0f, 0x01, 0xc8;" | |
28 | :: "a" (eax), "c" (ecx), "d"(edx)); | |
29 | } | |
30 | ||
f9675674 HR |
31 | static inline void __monitorx(const void *eax, unsigned long ecx, |
32 | unsigned long edx) | |
33 | { | |
34 | /* "monitorx %eax, %ecx, %edx;" */ | |
35 | asm volatile(".byte 0x0f, 0x01, 0xfa;" | |
36 | :: "a" (eax), "c" (ecx), "d"(edx)); | |
37 | } | |
38 | ||
16824255 PZ |
39 | static inline void __mwait(unsigned long eax, unsigned long ecx) |
40 | { | |
41 | /* "mwait %eax, %ecx;" */ | |
42 | asm volatile(".byte 0x0f, 0x01, 0xc9;" | |
43 | :: "a" (eax), "c" (ecx)); | |
44 | } | |
45 | ||
f9675674 HR |
46 | /* |
47 | * MWAITX allows for a timer expiration to get the core out a wait state in | |
48 | * addition to the default MWAIT exit condition of a store appearing at a | |
49 | * monitored virtual address. | |
50 | * | |
51 | * Registers: | |
52 | * | |
53 | * MWAITX ECX[1]: enable timer if set | |
54 | * MWAITX EBX[31:0]: max wait time expressed in SW P0 clocks. The software P0 | |
55 | * frequency is the same as the TSC frequency. | |
56 | * | |
57 | * Below is a comparison between MWAIT and MWAITX on AMD processors: | |
58 | * | |
59 | * MWAIT MWAITX | |
60 | * opcode 0f 01 c9 | 0f 01 fb | |
61 | * ECX[0] value of RFLAGS.IF seen by instruction | |
62 | * ECX[1] unused/#GP if set | enable timer if set | |
63 | * ECX[31:2] unused/#GP if set | |
64 | * EAX unused (reserve for hint) | |
65 | * EBX[31:0] unused | max wait time (P0 clocks) | |
66 | * | |
67 | * MONITOR MONITORX | |
68 | * opcode 0f 01 c8 | 0f 01 fa | |
69 | * EAX (logical) address to monitor | |
70 | * ECX #GP if not zero | |
71 | */ | |
72 | static inline void __mwaitx(unsigned long eax, unsigned long ebx, | |
73 | unsigned long ecx) | |
74 | { | |
75 | /* "mwaitx %eax, %ebx, %ecx;" */ | |
76 | asm volatile(".byte 0x0f, 0x01, 0xfb;" | |
77 | :: "a" (eax), "b" (ebx), "c" (ecx)); | |
78 | } | |
79 | ||
b253149b LB |
80 | static inline void __sti_mwait(unsigned long eax, unsigned long ecx) |
81 | { | |
82 | trace_hardirqs_on(); | |
83 | /* "mwait %eax, %ecx;" */ | |
84 | asm volatile("sti; .byte 0x0f, 0x01, 0xc9;" | |
85 | :: "a" (eax), "c" (ecx)); | |
86 | } | |
87 | ||
16824255 PZ |
88 | /* |
89 | * This uses new MONITOR/MWAIT instructions on P4 processors with PNI, | |
90 | * which can obviate IPI to trigger checking of need_resched. | |
91 | * We execute MONITOR against need_resched and enter optimized wait state | |
92 | * through MWAIT. Whenever someone changes need_resched, we would be woken | |
93 | * up from MWAIT (without an IPI). | |
94 | * | |
95 | * New with Core Duo processors, MWAIT can take some hints based on CPU | |
96 | * capability. | |
97 | */ | |
98 | static inline void mwait_idle_with_hints(unsigned long eax, unsigned long ecx) | |
99 | { | |
100 | if (!current_set_polling_and_test()) { | |
9b13a93d | 101 | if (static_cpu_has_bug(X86_BUG_CLFLUSH_MONITOR)) { |
7e98b719 | 102 | mb(); |
16824255 | 103 | clflush((void *)¤t_thread_info()->flags); |
7e98b719 PA |
104 | mb(); |
105 | } | |
16824255 PZ |
106 | |
107 | __monitor((void *)¤t_thread_info()->flags, 0, 0); | |
108 | if (!need_resched()) | |
109 | __mwait(eax, ecx); | |
110 | } | |
8cb75e0c | 111 | current_clr_polling(); |
16824255 PZ |
112 | } |
113 | ||
bc83cccc | 114 | #endif /* _ASM_X86_MWAIT_H */ |