1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/errno.h>
3 #include <linux/init.h>
5 #include <asm/sections.h>
6 #include <asm/mem_detect.h>
7 #include <asm/sparsemem.h>
8 #include "compressed/decompressor.h"
11 struct mem_detect_info __bootdata(mem_detect);
13 /* up to 256 storage elements, 1020 subincrements each */
14 #define ENTRIES_EXTENDED_MAX \
15 (256 * (1020 / 2) * sizeof(struct mem_detect_block))
18 * To avoid corrupting old kernel memory during dump, find lowest memory
19 * chunk possible either right after the kernel end (decompressed kernel) or
20 * after initrd (if it is present and there is no hole between the kernel end
23 static void *mem_detect_alloc_extended(void)
25 unsigned long offset = ALIGN(mem_safe_offset(), sizeof(u64));
27 if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && INITRD_START && INITRD_SIZE &&
28 INITRD_START < offset + ENTRIES_EXTENDED_MAX)
29 offset = ALIGN(INITRD_START + INITRD_SIZE, sizeof(u64));
31 return (void *)offset;
34 static struct mem_detect_block *__get_mem_detect_block_ptr(u32 n)
36 if (n < MEM_INLINED_ENTRIES)
37 return &mem_detect.entries[n];
38 if (unlikely(!mem_detect.entries_extended))
39 mem_detect.entries_extended = mem_detect_alloc_extended();
40 return &mem_detect.entries_extended[n - MEM_INLINED_ENTRIES];
44 * sequential calls to add_mem_detect_block with adjacent memory areas
45 * are merged together into single memory block.
47 void add_mem_detect_block(u64 start, u64 end)
49 struct mem_detect_block *block;
51 if (mem_detect.count) {
52 block = __get_mem_detect_block_ptr(mem_detect.count - 1);
53 if (block->end == start) {
59 block = __get_mem_detect_block_ptr(mem_detect.count);
65 static int __diag260(unsigned long rx1, unsigned long rx2)
67 unsigned long reg1, reg2, ry;
68 union register_pair rx;
74 ry = 0x10; /* storage configuration */
77 " mvc 0(16,%[psw_old]),0(%[psw_pgm])\n"
78 " epsw %[reg1],%[reg2]\n"
79 " st %[reg1],0(%[psw_pgm])\n"
80 " st %[reg2],4(%[psw_pgm])\n"
82 " stg %[reg1],8(%[psw_pgm])\n"
83 " diag %[rx],%[ry],0x260\n"
86 "1: mvc 0(16,%[psw_pgm]),0(%[psw_old])\n"
87 : [reg1] "=&d" (reg1),
91 "+Q" (S390_lowcore.program_new_psw),
95 [psw_pgm] "a" (&S390_lowcore.program_new_psw)
97 return rc == 0 ? ry : -1;
100 static int diag260(void)
107 } storage_extents[8] __aligned(16); /* VM supports up to 8 extends */
109 memset(storage_extents, 0, sizeof(storage_extents));
110 rc = __diag260((unsigned long)storage_extents, sizeof(storage_extents));
114 for (i = 0; i < min_t(int, rc, ARRAY_SIZE(storage_extents)); i++)
115 add_mem_detect_block(storage_extents[i].start, storage_extents[i].end + 1);
119 static int tprot(unsigned long addr)
121 unsigned long reg1, reg2;
126 " mvc 0(16,%[psw_old]),0(%[psw_pgm])\n"
127 " epsw %[reg1],%[reg2]\n"
128 " st %[reg1],0(%[psw_pgm])\n"
129 " st %[reg2],4(%[psw_pgm])\n"
131 " stg %[reg1],8(%[psw_pgm])\n"
132 " tprot 0(%[addr]),0\n"
135 "1: mvc 0(16,%[psw_pgm]),0(%[psw_old])\n"
136 : [reg1] "=&d" (reg1),
139 "=Q" (S390_lowcore.program_new_psw.addr),
141 : [psw_old] "a" (&old),
142 [psw_pgm] "a" (&S390_lowcore.program_new_psw),
148 static void search_mem_end(void)
150 unsigned long range = 1 << (MAX_PHYSMEM_BITS - 20); /* in 1MB blocks */
151 unsigned long offset = 0;
156 pivot = offset + range;
157 if (!tprot(pivot << 20))
161 add_mem_detect_block(0, (offset + 1) << 20);
164 unsigned long detect_memory(void)
166 unsigned long max_physmem_end;
168 sclp_early_get_memsize(&max_physmem_end);
170 if (!sclp_early_read_storage_info()) {
171 mem_detect.info_source = MEM_DETECT_SCLP_STOR_INFO;
172 return max_physmem_end;
176 mem_detect.info_source = MEM_DETECT_DIAG260;
177 return max_physmem_end;
180 if (max_physmem_end) {
181 add_mem_detect_block(0, max_physmem_end);
182 mem_detect.info_source = MEM_DETECT_SCLP_READ_INFO;
183 return max_physmem_end;
187 mem_detect.info_source = MEM_DETECT_BIN_SEARCH;
188 return get_mem_detect_end();