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
11unsigned long __bootdata(max_physmem_end);
12struct 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 */
24static 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
35static 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 */
48void 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
66static 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
97static 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
116static 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
145static 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
161void 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