1 #include <linux/export.h>
2 #include <linux/percpu.h>
3 #include <linux/preempt.h>
4 #include <asm/msr.h>
5 #define CREATE_TRACE_POINTS
6 #include <asm/msr-trace.h>
7
8 struct msr *msrs_alloc(void)
9 {
10 struct msr *msrs = NULL;
11
12 msrs = alloc_percpu(struct msr);
13 if (!msrs) {
14 pr_warn("%s: error allocating msrs\n", __func__);
15 return NULL;
16 }
17
18 return msrs;
19 }
20 EXPORT_SYMBOL(msrs_alloc);
21
22 void msrs_free(struct msr *msrs)
23 {
24 free_percpu(msrs);
25 }
26 EXPORT_SYMBOL(msrs_free);
27
28 /**
29 * Read an MSR with error handling
30 *
31 * @msr: MSR to read
32 * @m: value to read into
33 *
34 * It returns read data only on success, otherwise it doesn't change the output
35 * argument @m.
36 *
37 */
38 int msr_read(u32 msr, struct msr *m)
39 {
40 int err;
41 u64 val;
42
43 err = rdmsrl_safe(msr, &val);
44 if (!err)
45 m->q = val;
46
47 return err;
48 }
49
50 /**
51 * Write an MSR with error handling
52 *
53 * @msr: MSR to write
54 * @m: value to write
55 */
56 int msr_write(u32 msr, struct msr *m)
57 {
58 return wrmsrl_safe(msr, m->q);
59 }
60
61 static inline int __flip_bit(u32 msr, u8 bit, bool set)
62 {
63 struct msr m, m1;
64 int err = -EINVAL;
65
66 if (bit > 63)
67 return err;
68
69 err = msr_read(msr, &m);
70 if (err)
71 return err;
72
73 m1 = m;
74 if (set)
75 m1.q |= BIT_64(bit);
76 else
77 m1.q &= ~BIT_64(bit);
78
79 if (m1.q == m.q)
80 return 0;
81
82 err = msr_write(msr, &m1);
83 if (err)
84 return err;
85
86 return 1;
87 }
88
89 /**
90 * Set @bit in a MSR @msr.
91 *
92 * Retval:
93 * < 0: An error was encountered.
94 * = 0: Bit was already set.
95 * > 0: Hardware accepted the MSR write.
96 */
97 int msr_set_bit(u32 msr, u8 bit)
98 {
99 return __flip_bit(msr, bit, true);
100 }
101
102 /**
103 * Clear @bit in a MSR @msr.
104 *
105 * Retval:
106 * < 0: An error was encountered.
107 * = 0: Bit was already cleared.
108 * > 0: Hardware accepted the MSR write.
109 */
110 int msr_clear_bit(u32 msr, u8 bit)
111 {
112 return __flip_bit(msr, bit, false);
113 }
114
115 #ifdef CONFIG_TRACEPOINTS
116 void do_trace_write_msr(unsigned msr, u64 val, int failed)
117 {
118 trace_write_msr(msr, val, failed);
119 }
120 EXPORT_SYMBOL(do_trace_write_msr);
121 EXPORT_TRACEPOINT_SYMBOL(write_msr);
122
123 void do_trace_read_msr(unsigned msr, u64 val, int failed)
124 {
125 trace_read_msr(msr, val, failed);
126 }
127 EXPORT_SYMBOL(do_trace_read_msr);
128 EXPORT_TRACEPOINT_SYMBOL(read_msr);
129
130 void do_trace_rdpmc(unsigned counter, u64 val, int failed)
131 {
132 trace_rdpmc(counter, val, failed);
133 }
134 EXPORT_SYMBOL(do_trace_rdpmc);
135 EXPORT_TRACEPOINT_SYMBOL(rdpmc);
136
137 #endif
138
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