1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/export.h>
3 #include <linux/percpu.h>
4 #include <linux/preempt.h>
5 #include <asm/msr.h>
6 #define CREATE_TRACE_POINTS
7 #include <asm/msr-trace.h>
8
9 struct msr __percpu *msrs_alloc(void)
10 {
11 struct msr __percpu *msrs = NULL;
12
13 msrs = alloc_percpu(struct msr);
14 if (!msrs) {
15 pr_warn("%s: error allocating msrs\n", __func__);
16 return NULL;
17 }
18
19 return msrs;
20 }
21 EXPORT_SYMBOL(msrs_alloc);
22
23 void msrs_free(struct msr __percpu *msrs)
24 {
25 free_percpu(msrs);
26 }
27 EXPORT_SYMBOL(msrs_free);
28
29 /**
30 * msr_read - Read an MSR with error handling
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 * Return: %0 for success, otherwise an error code
38 */
39 static int msr_read(u32 msr, struct msr *m)
40 {
41 int err;
42 u64 val;
43
44 err = rdmsrl_safe(msr, &val);
45 if (!err)
46 m->q = val;
47
48 return err;
49 }
50
51 /**
52 * msr_write - Write an MSR with error handling
53 *
54 * @msr: MSR to write
55 * @m: value to write
56 *
57 * Return: %0 for success, otherwise an error code
58 */
59 static int msr_write(u32 msr, struct msr *m)
60 {
61 return wrmsrl_safe(msr, m->q);
62 }
63
64 static inline int __flip_bit(u32 msr, u8 bit, bool set)
65 {
66 struct msr m, m1;
67 int err = -EINVAL;
68
69 if (bit > 63)
70 return err;
71
72 err = msr_read(msr, &m);
73 if (err)
74 return err;
75
76 m1 = m;
77 if (set)
78 m1.q |= BIT_64(bit);
79 else
80 m1.q &= ~BIT_64(bit);
81
82 if (m1.q == m.q)
83 return 0;
84
85 err = msr_write(msr, &m1);
86 if (err)
87 return err;
88
89 return 1;
90 }
91
92 /**
93 * msr_set_bit - Set @bit in a MSR @msr.
94 * @msr: MSR to write
95 * @bit: bit number to set
96 *
97 * Return:
98 * * < 0: An error was encountered.
99 * * = 0: Bit was already set.
100 * * > 0: Hardware accepted the MSR write.
101 */
102 int msr_set_bit(u32 msr, u8 bit)
103 {
104 return __flip_bit(msr, bit, true);
105 }
106
107 /**
108 * msr_clear_bit - Clear @bit in a MSR @msr.
109 * @msr: MSR to write
110 * @bit: bit number to clear
111 *
112 * Return:
113 * * < 0: An error was encountered.
114 * * = 0: Bit was already cleared.
115 * * > 0: Hardware accepted the MSR write.
116 */
117 int msr_clear_bit(u32 msr, u8 bit)
118 {
119 return __flip_bit(msr, bit, false);
120 }
121
122 #ifdef CONFIG_TRACEPOINTS
123 void do_trace_write_msr(unsigned int msr, u64 val, int failed)
124 {
125 trace_write_msr(msr, val, failed);
126 }
127 EXPORT_SYMBOL(do_trace_write_msr);
128 EXPORT_TRACEPOINT_SYMBOL(write_msr);
129
130 void do_trace_read_msr(unsigned int msr, u64 val, int failed)
131 {
132 trace_read_msr(msr, val, failed);
133 }
134 EXPORT_SYMBOL(do_trace_read_msr);
135 EXPORT_TRACEPOINT_SYMBOL(read_msr);
136
137 void do_trace_rdpmc(unsigned counter, u64 val, int failed)
138 {
139 trace_rdpmc(counter, val, failed);
140 }
141 EXPORT_SYMBOL(do_trace_rdpmc);
142 EXPORT_TRACEPOINT_SYMBOL(rdpmc);
143
144 #endif
145
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