1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/errno.h>
3 #include <linux/init.h>
4 #include <asm/sclp.h>
5 #include <asm/sections.h>
6 #include <asm/mem_detect.h>
7 #include <asm/sparsemem.h>
8 #include "compressed/decompressor.h"
9 #include "boot.h"
10
11 unsigned long __bootdata(max_physmem_end);
12 struct mem_detect_info __bootdata(mem_detect);
13
14 /* up to 256 storage elements, 1020 subincrements each */
15 #define ENTRIES_EXTENDED_MAX \
16 (256 * (1020 / 2) * sizeof(struct mem_detect_block))
17
18 /*
19 * To avoid corrupting old kernel memory during dump, find lowest memory
20 * chunk possible either right after the kernel end (decompressed kernel) or
21 * after initrd (if it is present and there is no hole between the kernel end
22 * and initrd)
23 */
mem_detect_alloc_extended(void)24 static void *mem_detect_alloc_extended(void)
25 {
26 unsigned long offset = ALIGN(mem_safe_offset(), sizeof(u64));
27
28 if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && INITRD_START && INITRD_SIZE &&
29 INITRD_START < offset + ENTRIES_EXTENDED_MAX)
30 offset = ALIGN(INITRD_START + INITRD_SIZE, sizeof(u64));
31
32 return (void *)offset;
33 }
34
__get_mem_detect_block_ptr(u32 n)35 static struct mem_detect_block *__get_mem_detect_block_ptr(u32 n)
36 {
37 if (n < MEM_INLINED_ENTRIES)
38 return &mem_detect.entries[n];
39 if (unlikely(!mem_detect.entries_extended))
40 mem_detect.entries_extended = mem_detect_alloc_extended();
41 return &mem_detect.entries_extended[n - MEM_INLINED_ENTRIES];
42 }
43
44 /*
45 * sequential calls to add_mem_detect_block with adjacent memory areas
46 * are merged together into single memory block.
47 */
add_mem_detect_block(u64 start,u64 end)48 void add_mem_detect_block(u64 start, u64 end)
49 {
50 struct mem_detect_block *block;
51
52 if (mem_detect.count) {
53 block = __get_mem_detect_block_ptr(mem_detect.count - 1);
54 if (block->end == start) {
55 block->end = end;
56 return;
57 }
58 }
59
60 block = __get_mem_detect_block_ptr(mem_detect.count);
61 block->start = start;
62 block->end = end;
63 mem_detect.count++;
64 }
65
__diag260(unsigned long rx1,unsigned long rx2)66 static int __diag260(unsigned long rx1, unsigned long rx2)
67 {
68 register unsigned long _rx1 asm("2") = rx1;
69 register unsigned long _rx2 asm("3") = rx2;
70 register unsigned long _ry asm("4") = 0x10; /* storage configuration */
71 int rc = -1; /* fail */
72 unsigned long reg1, reg2;
73 psw_t old;
74
75 asm volatile(
76 " mvc 0(16,%[psw_old]),0(%[psw_pgm])\n"
77 " epsw %0,%1\n"
78 " st %0,0(%[psw_pgm])\n"
79 " st %1,4(%[psw_pgm])\n"
80 " larl %0,1f\n"
81 " stg %0,8(%[psw_pgm])\n"
82 " diag %[rx],%[ry],0x260\n"
83 " ipm %[rc]\n"
84 " srl %[rc],28\n"
85 "1: mvc 0(16,%[psw_pgm]),0(%[psw_old])\n"
86 : "=&d" (reg1), "=&a" (reg2),
87 "+Q" (S390_lowcore.program_new_psw),
88 "=Q" (old),
89 [rc] "+&d" (rc), [ry] "+d" (_ry)
90 : [rx] "d" (_rx1), "d" (_rx2),
91 [psw_old] "a" (&old),
92 [psw_pgm] "a" (&S390_lowcore.program_new_psw)
93 : "cc", "memory");
94 return rc == 0 ? _ry : -1;
95 }
96
diag260(void)97 static int diag260(void)
98 {
99 int rc, i;
100
101 struct {
102 unsigned long start;
103 unsigned long end;
104 } storage_extents[8] __aligned(16); /* VM supports up to 8 extends */
105
106 memset(storage_extents, 0, sizeof(storage_extents));
107 rc = __diag260((unsigned long)storage_extents, sizeof(storage_extents));
108 if (rc == -1)
109 return -1;
110
111 for (i = 0; i < min_t(int, rc, ARRAY_SIZE(storage_extents)); i++)
112 add_mem_detect_block(storage_extents[i].start, storage_extents[i].end + 1);
113 return 0;
114 }
115
tprot(unsigned long addr)116 static int tprot(unsigned long addr)
117 {
118 unsigned long reg1, reg2;
119 int rc = -EFAULT;
120 psw_t old;
121
122 asm volatile(
123 " mvc 0(16,%[psw_old]),0(%[psw_pgm])\n"
124 " epsw %[reg1],%[reg2]\n"
125 " st %[reg1],0(%[psw_pgm])\n"
126 " st %[reg2],4(%[psw_pgm])\n"
127 " larl %[reg1],1f\n"
128 " stg %[reg1],8(%[psw_pgm])\n"
129 " tprot 0(%[addr]),0\n"
130 " ipm %[rc]\n"
131 " srl %[rc],28\n"
132 "1: mvc 0(16,%[psw_pgm]),0(%[psw_old])\n"
133 : [reg1] "=&d" (reg1),
134 [reg2] "=&a" (reg2),
135 [rc] "+&d" (rc),
136 "=Q" (S390_lowcore.program_new_psw.addr),
137 "=Q" (old)
138 : [psw_old] "a" (&old),
139 [psw_pgm] "a" (&S390_lowcore.program_new_psw),
140 [addr] "a" (addr)
141 : "cc", "memory");
142 return rc;
143 }
144
search_mem_end(void)145 static void search_mem_end(void)
146 {
147 unsigned long range = 1 << (MAX_PHYSMEM_BITS - 20); /* in 1MB blocks */
148 unsigned long offset = 0;
149 unsigned long pivot;
150
151 while (range > 1) {
152 range >>= 1;
153 pivot = offset + range;
154 if (!tprot(pivot << 20))
155 offset = pivot;
156 }
157
158 add_mem_detect_block(0, (offset + 1) << 20);
159 }
160
detect_memory(void)161 void detect_memory(void)
162 {
163 sclp_early_get_memsize(&max_physmem_end);
164
165 if (!sclp_early_read_storage_info()) {
166 mem_detect.info_source = MEM_DETECT_SCLP_STOR_INFO;
167 return;
168 }
169
170 if (!diag260()) {
171 mem_detect.info_source = MEM_DETECT_DIAG260;
172 return;
173 }
174
175 if (max_physmem_end) {
176 add_mem_detect_block(0, max_physmem_end);
177 mem_detect.info_source = MEM_DETECT_SCLP_READ_INFO;
178 return;
179 }
180
181 search_mem_end();
182 mem_detect.info_source = MEM_DETECT_BIN_SEARCH;
183 max_physmem_end = get_mem_detect_end();
184 }
185