xref: /linux/arch/s390/include/asm/facility.h (revision e3fc2fd77c63cd2e37ebd33a336602a68650f22b)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * Copyright IBM Corp. 1999, 2009
4  *
5  * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
6  */
7 
8 #ifndef __ASM_FACILITY_H
9 #define __ASM_FACILITY_H
10 
11 #include <asm/facility-defs.h>
12 
13 #include <linux/minmax.h>
14 #include <linux/string.h>
15 #include <linux/types.h>
16 #include <linux/preempt.h>
17 #include <asm/alternative.h>
18 #include <asm/lowcore.h>
19 
20 #define MAX_FACILITY_BIT (sizeof(stfle_fac_list) * 8)
21 
22 extern u64 stfle_fac_list[16];
23 
24 static inline void __set_facility(unsigned long nr, void *facilities)
25 {
26 	unsigned char *ptr = (unsigned char *) facilities;
27 
28 	if (nr >= MAX_FACILITY_BIT)
29 		return;
30 	ptr[nr >> 3] |= 0x80 >> (nr & 7);
31 }
32 
33 static inline void __clear_facility(unsigned long nr, void *facilities)
34 {
35 	unsigned char *ptr = (unsigned char *) facilities;
36 
37 	if (nr >= MAX_FACILITY_BIT)
38 		return;
39 	ptr[nr >> 3] &= ~(0x80 >> (nr & 7));
40 }
41 
42 static __always_inline bool __test_facility(unsigned long nr, void *facilities)
43 {
44 	unsigned char *ptr;
45 
46 	if (nr >= MAX_FACILITY_BIT)
47 		return false;
48 	ptr = (unsigned char *) facilities + (nr >> 3);
49 	return (*ptr & (0x80 >> (nr & 7))) != 0;
50 }
51 
52 /*
53  * __test_facility_constant() generates a single instruction branch. If the
54  * tested facility is available (likely) the branch is patched into a nop.
55  *
56  * Do not use this function unless you know what you are doing. All users are
57  * supposed to use test_facility() which will do the right thing.
58  */
59 static __always_inline bool __test_facility_constant(unsigned long nr)
60 {
61 	asm goto(
62 		ALTERNATIVE("brcl 15,%l[l_no]", "brcl 0,0", ALT_FACILITY(%[nr]))
63 		:
64 		: [nr] "i" (nr)
65 		:
66 		: l_no);
67 	return true;
68 l_no:
69 	return false;
70 }
71 
72 /*
73  * The test_facility function uses the bit ordering where the MSB is bit 0.
74  * That makes it easier to query facility bits with the bit number as
75  * documented in the Principles of Operation.
76  */
77 static __always_inline bool test_facility(unsigned long nr)
78 {
79 	unsigned long facilities_als[] = { FACILITIES_ALS };
80 
81 	if (!__is_defined(__DECOMPRESSOR) && __builtin_constant_p(nr)) {
82 		if (nr < sizeof(facilities_als) * 8) {
83 			if (__test_facility(nr, &facilities_als))
84 				return true;
85 		}
86 		return __test_facility_constant(nr);
87 	}
88 	return __test_facility(nr, &stfle_fac_list);
89 }
90 
91 static inline unsigned long __stfle_asm(u64 *stfle_fac_list, int size)
92 {
93 	unsigned long reg0 = size - 1;
94 
95 	asm volatile(
96 		"	lgr	0,%[reg0]\n"
97 		"	.insn	s,0xb2b00000,%[list]\n" /* stfle */
98 		"	lgr	%[reg0],0\n"
99 		: [reg0] "+&d" (reg0), [list] "+Q" (*stfle_fac_list)
100 		:
101 		: "memory", "cc", "0");
102 	return reg0;
103 }
104 
105 /**
106  * stfle - Store facility list extended
107  * @stfle_fac_list: array where facility list can be stored
108  * @size: size of passed in array in double words
109  */
110 static inline void __stfle(u64 *stfle_fac_list, int size)
111 {
112 	unsigned long nr;
113 	u32 stfl_fac_list;
114 
115 	asm volatile(
116 		"	stfl	0(0)\n"
117 		: "=m" (get_lowcore()->stfl_fac_list));
118 	stfl_fac_list = get_lowcore()->stfl_fac_list;
119 	memcpy(stfle_fac_list, &stfl_fac_list, 4);
120 	nr = 4; /* bytes stored by stfl */
121 	if (stfl_fac_list & 0x01000000) {
122 		/* More facility bits available with stfle */
123 		nr = __stfle_asm(stfle_fac_list, size);
124 		nr = min_t(unsigned long, (nr + 1) * 8, size * 8);
125 	}
126 	memset((char *) stfle_fac_list + nr, 0, size * 8 - nr);
127 }
128 
129 static inline void stfle(u64 *stfle_fac_list, int size)
130 {
131 	preempt_disable();
132 	__stfle(stfle_fac_list, size);
133 	preempt_enable();
134 }
135 
136 /**
137  * stfle_size - Actual size of the facility list as specified by stfle
138  * (number of double words)
139  */
140 unsigned int stfle_size(void);
141 
142 #endif /* __ASM_FACILITY_H */
143