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
 11struct mem_detect_info __bootdata(mem_detect);
 12
 13/* up to 256 storage elements, 1020 subincrements each */
 14#define ENTRIES_EXTENDED_MAX						       \
 15	(256 * (1020 / 2) * sizeof(struct mem_detect_block))
 16
 17/*
 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
 21 * and initrd)
 22 */
 23static void *mem_detect_alloc_extended(void)
 24{
 25	unsigned long offset = ALIGN(mem_safe_offset(), sizeof(u64));
 26
 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));
 30
 31	return (void *)offset;
 32}
 33
 34static struct mem_detect_block *__get_mem_detect_block_ptr(u32 n)
 35{
 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];
 41}
 42
 43/*
 44 * sequential calls to add_mem_detect_block with adjacent memory areas
 45 * are merged together into single memory block.
 46 */
 47void add_mem_detect_block(u64 start, u64 end)
 48{
 49	struct mem_detect_block *block;
 50
 51	if (mem_detect.count) {
 52		block = __get_mem_detect_block_ptr(mem_detect.count - 1);
 53		if (block->end == start) {
 54			block->end = end;
 55			return;
 56		}
 57	}
 58
 59	block = __get_mem_detect_block_ptr(mem_detect.count);
 60	block->start = start;
 61	block->end = end;
 62	mem_detect.count++;
 63}
 64
 65static int __diag260(unsigned long rx1, unsigned long rx2)
 66{
 67	unsigned long reg1, reg2, ry;
 68	union register_pair rx;
 69	psw_t old;
 70	int rc;
 71
 72	rx.even = rx1;
 73	rx.odd	= rx2;
 74	ry = 0x10; /* storage configuration */
 75	rc = -1;   /* fail */
 76	asm volatile(
 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"
 81		"	larl	%[reg1],1f\n"
 82		"	stg	%[reg1],8(%[psw_pgm])\n"
 83		"	diag	%[rx],%[ry],0x260\n"
 84		"	ipm	%[rc]\n"
 85		"	srl	%[rc],28\n"
 86		"1:	mvc	0(16,%[psw_pgm]),0(%[psw_old])\n"
 87		: [reg1] "=&d" (reg1),
 88		  [reg2] "=&a" (reg2),
 89		  [rc] "+&d" (rc),
 90		  [ry] "+&d" (ry),
 91		  "+Q" (S390_lowcore.program_new_psw),
 92		  "=Q" (old)
 93		: [rx] "d" (rx.pair),
 94		  [psw_old] "a" (&old),
 95		  [psw_pgm] "a" (&S390_lowcore.program_new_psw)
 96		: "cc", "memory");
 97	return rc == 0 ? ry : -1;
 98}
 99
100static int diag260(void)
101{
102	int rc, i;
103
104	struct {
105		unsigned long start;
106		unsigned long end;
107	} storage_extents[8] __aligned(16); /* VM supports up to 8 extends */
108
109	memset(storage_extents, 0, sizeof(storage_extents));
110	rc = __diag260((unsigned long)storage_extents, sizeof(storage_extents));
111	if (rc == -1)
112		return -1;
113
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);
116	return 0;
117}
118
119static int tprot(unsigned long addr)
120{
121	unsigned long reg1, reg2;
122	int rc = -EFAULT;
123	psw_t old;
124
125	asm volatile(
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"
130		"	larl	%[reg1],1f\n"
131		"	stg	%[reg1],8(%[psw_pgm])\n"
132		"	tprot	0(%[addr]),0\n"
133		"	ipm	%[rc]\n"
134		"	srl	%[rc],28\n"
135		"1:	mvc	0(16,%[psw_pgm]),0(%[psw_old])\n"
136		: [reg1] "=&d" (reg1),
137		  [reg2] "=&a" (reg2),
138		  [rc] "+&d" (rc),
139		  "=Q" (S390_lowcore.program_new_psw.addr),
140		  "=Q" (old)
141		: [psw_old] "a" (&old),
142		  [psw_pgm] "a" (&S390_lowcore.program_new_psw),
143		  [addr] "a" (addr)
144		: "cc", "memory");
145	return rc;
146}
147
148static void search_mem_end(void)
149{
150	unsigned long range = 1 << (MAX_PHYSMEM_BITS - 20); /* in 1MB blocks */
151	unsigned long offset = 0;
152	unsigned long pivot;
153
154	while (range > 1) {
155		range >>= 1;
156		pivot = offset + range;
157		if (!tprot(pivot << 20))
158			offset = pivot;
159	}
160
161	add_mem_detect_block(0, (offset + 1) << 20);
162}
163
164unsigned long detect_memory(void)
165{
166	unsigned long max_physmem_end;
167
168	sclp_early_get_memsize(&max_physmem_end);
169
170	if (!sclp_early_read_storage_info()) {
171		mem_detect.info_source = MEM_DETECT_SCLP_STOR_INFO;
172		return max_physmem_end;
173	}
174
175	if (!diag260()) {
176		mem_detect.info_source = MEM_DETECT_DIAG260;
177		return max_physmem_end;
178	}
179
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;
184	}
185
186	search_mem_end();
187	mem_detect.info_source = MEM_DETECT_BIN_SEARCH;
188	return get_mem_detect_end();
189}