summaryrefslogtreecommitdiff
path: root/arch/s390/kernel/mem_detect.c
blob: 22d502e885ed2b5f0b6c84c45c10e11bf47535da (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
/*
 * Copyright IBM Corp. 2008, 2009
 *
 * Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <asm/ipl.h>
#include <asm/sclp.h>
#include <asm/setup.h>

#define ADDR2G (1ULL << 31)

static void find_memory_chunks(struct mem_chunk chunk[])
{
	unsigned long long memsize, rnmax, rzm;
	unsigned long addr = 0, size;
	int i = 0, type;

	rzm = sclp_get_rzm();
	rnmax = sclp_get_rnmax();
	memsize = rzm * rnmax;
	if (!rzm)
		rzm = 1ULL << 17;
	if (sizeof(long) == 4) {
		rzm = min(ADDR2G, rzm);
		memsize = memsize ? min(ADDR2G, memsize) : ADDR2G;
	}
	do {
		size = 0;
		type = tprot(addr);
		do {
			size += rzm;
			if (memsize && addr + size >= memsize)
				break;
		} while (type == tprot(addr + size));
		if (type == CHUNK_READ_WRITE || type == CHUNK_READ_ONLY) {
			chunk[i].addr = addr;
			chunk[i].size = size;
			chunk[i].type = type;
			i++;
		}
		addr += size;
	} while (addr < memsize && i < MEMORY_CHUNKS);
}

void detect_memory_layout(struct mem_chunk chunk[])
{
	unsigned long flags, cr0;

	memset(chunk, 0, MEMORY_CHUNKS * sizeof(struct mem_chunk));
	/* Disable IRQs, DAT and low address protection so tprot does the
	 * right thing and we don't get scheduled away with low address
	 * protection disabled.
	 */
	flags = __arch_local_irq_stnsm(0xf8);
	__ctl_store(cr0, 0, 0);
	__ctl_clear_bit(0, 28);
	find_memory_chunks(chunk);
	__ctl_load(cr0, 0, 0);
	arch_local_irq_restore(flags);
}
EXPORT_SYMBOL(detect_memory_layout);

/*
 * Move memory chunks array from index "from" to index "to"
 */
static void mem_chunk_move(struct mem_chunk chunk[], int to, int from)
{
	int cnt = MEMORY_CHUNKS - to;

	memmove(&chunk[to], &chunk[from], cnt * sizeof(struct mem_chunk));
}

/*
 * Initialize memory chunk
 */
static void mem_chunk_init(struct mem_chunk *chunk, unsigned long addr,
			   unsigned long size, int type)
{
	chunk->type = type;
	chunk->addr = addr;
	chunk->size = size;
}

/*
 * Create memory hole with given address, size, and type
 */
void create_mem_hole(struct mem_chunk chunk[], unsigned long addr,
		     unsigned long size, int type)
{
	unsigned long lh_start, lh_end, lh_size, ch_start, ch_end, ch_size;
	int i, ch_type;

	for (i = 0; i < MEMORY_CHUNKS; i++) {
		if (chunk[i].size == 0)
			continue;

		/* Define chunk properties */
		ch_start = chunk[i].addr;
		ch_size = chunk[i].size;
		ch_end = ch_start + ch_size - 1;
		ch_type = chunk[i].type;

		/* Is memory chunk hit by memory hole? */
		if (addr + size <= ch_start)
			continue; /* No: memory hole in front of chunk */
		if (addr > ch_end)
			continue; /* No: memory hole after chunk */

		/* Yes: Define local hole properties */
		lh_start = max(addr, chunk[i].addr);
		lh_end = min(addr + size - 1, ch_end);
		lh_size = lh_end - lh_start + 1;

		if (lh_start == ch_start && lh_end == ch_end) {
			/* Hole covers complete memory chunk */
			mem_chunk_init(&chunk[i], lh_start, lh_size, type);
		} else if (lh_end == ch_end) {
			/* Hole starts in memory chunk and convers chunk end */
			mem_chunk_move(chunk, i + 1, i);
			mem_chunk_init(&chunk[i], ch_start, ch_size - lh_size,
				       ch_type);
			mem_chunk_init(&chunk[i + 1], lh_start, lh_size, type);
			i += 1;
		} else if (lh_start == ch_start) {
			/* Hole ends in memory chunk */
			mem_chunk_move(chunk, i + 1, i);
			mem_chunk_init(&chunk[i], lh_start, lh_size, type);
			mem_chunk_init(&chunk[i + 1], lh_end + 1,
				       ch_size - lh_size, ch_type);
			break;
		} else {
			/* Hole splits memory chunk */
			mem_chunk_move(chunk, i + 2, i);
			mem_chunk_init(&chunk[i], ch_start,
				       lh_start - ch_start, ch_type);
			mem_chunk_init(&chunk[i + 1], lh_start, lh_size, type);
			mem_chunk_init(&chunk[i + 2], lh_end + 1,
				       ch_end - lh_end, ch_type);
			break;
		}
	}
}