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 = S390_lowcore.program_new_psw;
74
75 asm volatile(
76 " epsw %0,%1\n"
77 " st %0,%[psw_pgm]\n"
78 " st %1,%[psw_pgm]+4\n"
79 " larl %0,1f\n"
80 " stg %0,%[psw_pgm]+8\n"
81 " diag %[rx],%[ry],0x260\n"
82 " ipm %[rc]\n"
83 " srl %[rc],28\n"
84 "1:\n"
85 : "=&d" (reg1), "=&a" (reg2),
86 [psw_pgm] "=Q" (S390_lowcore.program_new_psw),
87 [rc] "+&d" (rc), [ry] "+d" (_ry)
88 : [rx] "d" (_rx1), "d" (_rx2)
89 : "cc", "memory");
90 S390_lowcore.program_new_psw = old;
91 return rc == 0 ? _ry : -1;
92 }
93
diag260(void)94 static int diag260(void)
95 {
96 int rc, i;
97
98 struct {
99 unsigned long start;
100 unsigned long end;
101 } storage_extents[8] __aligned(16); /* VM supports up to 8 extends */
102
103 memset(storage_extents, 0, sizeof(storage_extents));
104 rc = __diag260((unsigned long)storage_extents, sizeof(storage_extents));
105 if (rc == -1)
106 return -1;
107
108 for (i = 0; i < min_t(int, rc, ARRAY_SIZE(storage_extents)); i++)
109 add_mem_detect_block(storage_extents[i].start, storage_extents[i].end + 1);
110 return 0;
111 }
112
tprot(unsigned long addr)113 static int tprot(unsigned long addr)
114 {
115 unsigned long pgm_addr;
116 int rc = -EFAULT;
117 psw_t old = S390_lowcore.program_new_psw;
118
119 S390_lowcore.program_new_psw.mask = __extract_psw();
120 asm volatile(
121 " larl %[pgm_addr],1f\n"
122 " stg %[pgm_addr],%[psw_pgm_addr]\n"
123 " tprot 0(%[addr]),0\n"
124 " ipm %[rc]\n"
125 " srl %[rc],28\n"
126 "1:\n"
127 : [pgm_addr] "=&d"(pgm_addr),
128 [psw_pgm_addr] "=Q"(S390_lowcore.program_new_psw.addr),
129 [rc] "+&d"(rc)
130 : [addr] "a"(addr)
131 : "cc", "memory");
132 S390_lowcore.program_new_psw = old;
133 return rc;
134 }
135
search_mem_end(void)136 static void search_mem_end(void)
137 {
138 unsigned long range = 1 << (MAX_PHYSMEM_BITS - 20); /* in 1MB blocks */
139 unsigned long offset = 0;
140 unsigned long pivot;
141
142 while (range > 1) {
143 range >>= 1;
144 pivot = offset + range;
145 if (!tprot(pivot << 20))
146 offset = pivot;
147 }
148
149 add_mem_detect_block(0, (offset + 1) << 20);
150 }
151
detect_memory(void)152 void detect_memory(void)
153 {
154 sclp_early_get_memsize(&max_physmem_end);
155
156 if (!sclp_early_read_storage_info()) {
157 mem_detect.info_source = MEM_DETECT_SCLP_STOR_INFO;
158 return;
159 }
160
161 if (!diag260()) {
162 mem_detect.info_source = MEM_DETECT_DIAG260;
163 return;
164 }
165
166 if (max_physmem_end) {
167 add_mem_detect_block(0, max_physmem_end);
168 mem_detect.info_source = MEM_DETECT_SCLP_READ_INFO;
169 return;
170 }
171
172 search_mem_end();
173 mem_detect.info_source = MEM_DETECT_BIN_SEARCH;
174 max_physmem_end = get_mem_detect_end();
175 }
176