1// SPDX-License-Identifier: GPL-2.0
  2#include <linux/errno.h>
  3#include <linux/init.h>
  4#include <asm/setup.h>
  5#include <asm/processor.h>
  6#include <asm/sclp.h>
  7#include <asm/sections.h>
  8#include <asm/mem_detect.h>
  9#include <asm/sparsemem.h>
 10#include "decompressor.h"
 11#include "boot.h"
 12
 13struct mem_detect_info __bootdata(mem_detect);
 14
 15/* up to 256 storage elements, 1020 subincrements each */
 16#define ENTRIES_EXTENDED_MAX						       \
 17	(256 * (1020 / 2) * sizeof(struct mem_detect_block))
 18
 19/*
 20 * To avoid corrupting old kernel memory during dump, find lowest memory
 21 * chunk possible either right after the kernel end (decompressed kernel) or
 22 * after initrd (if it is present and there is no hole between the kernel end
 23 * and initrd)
 24 */
 25static void *mem_detect_alloc_extended(void)
 26{
 27	unsigned long offset = ALIGN(mem_safe_offset(), sizeof(u64));
 28
 29	if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && initrd_data.start && initrd_data.size &&
 30	    initrd_data.start < offset + ENTRIES_EXTENDED_MAX)
 31		offset = ALIGN(initrd_data.start + initrd_data.size, sizeof(u64));
 32
 33	return (void *)offset;
 34}
 35
 36static struct mem_detect_block *__get_mem_detect_block_ptr(u32 n)
 37{
 38	if (n < MEM_INLINED_ENTRIES)
 39		return &mem_detect.entries[n];
 40	if (unlikely(!mem_detect.entries_extended))
 41		mem_detect.entries_extended = mem_detect_alloc_extended();
 42	return &mem_detect.entries_extended[n - MEM_INLINED_ENTRIES];
 43}
 44
 45/*
 46 * sequential calls to add_mem_detect_block with adjacent memory areas
 47 * are merged together into single memory block.
 48 */
 49void add_mem_detect_block(u64 start, u64 end)
 50{
 51	struct mem_detect_block *block;
 52
 53	if (mem_detect.count) {
 54		block = __get_mem_detect_block_ptr(mem_detect.count - 1);
 55		if (block->end == start) {
 56			block->end = end;
 57			return;
 58		}
 59	}
 60
 61	block = __get_mem_detect_block_ptr(mem_detect.count);
 62	block->start = start;
 63	block->end = end;
 64	mem_detect.count++;
 65}
 66
 67static int __diag260(unsigned long rx1, unsigned long rx2)
 68{
 69	unsigned long reg1, reg2, ry;
 70	union register_pair rx;
 71	psw_t old;
 72	int rc;
 73
 74	rx.even = rx1;
 75	rx.odd	= rx2;
 76	ry = 0x10; /* storage configuration */
 77	rc = -1;   /* fail */
 78	asm volatile(
 79		"	mvc	0(16,%[psw_old]),0(%[psw_pgm])\n"
 80		"	epsw	%[reg1],%[reg2]\n"
 81		"	st	%[reg1],0(%[psw_pgm])\n"
 82		"	st	%[reg2],4(%[psw_pgm])\n"
 83		"	larl	%[reg1],1f\n"
 84		"	stg	%[reg1],8(%[psw_pgm])\n"
 85		"	diag	%[rx],%[ry],0x260\n"
 86		"	ipm	%[rc]\n"
 87		"	srl	%[rc],28\n"
 88		"1:	mvc	0(16,%[psw_pgm]),0(%[psw_old])\n"
 89		: [reg1] "=&d" (reg1),
 90		  [reg2] "=&a" (reg2),
 91		  [rc] "+&d" (rc),
 92		  [ry] "+&d" (ry),
 93		  "+Q" (S390_lowcore.program_new_psw),
 94		  "=Q" (old)
 95		: [rx] "d" (rx.pair),
 96		  [psw_old] "a" (&old),
 97		  [psw_pgm] "a" (&S390_lowcore.program_new_psw)
 98		: "cc", "memory");
 99	return rc == 0 ? ry : -1;
100}
101
102static int diag260(void)
103{
104	int rc, i;
105
106	struct {
107		unsigned long start;
108		unsigned long end;
109	} storage_extents[8] __aligned(16); /* VM supports up to 8 extends */
110
111	memset(storage_extents, 0, sizeof(storage_extents));
112	rc = __diag260((unsigned long)storage_extents, sizeof(storage_extents));
113	if (rc == -1)
114		return -1;
115
116	for (i = 0; i < min_t(int, rc, ARRAY_SIZE(storage_extents)); i++)
117		add_mem_detect_block(storage_extents[i].start, storage_extents[i].end + 1);
118	return 0;
119}
120
121static int tprot(unsigned long addr)
122{
123	unsigned long reg1, reg2;
124	int rc = -EFAULT;
125	psw_t old;
126
127	asm volatile(
128		"	mvc	0(16,%[psw_old]),0(%[psw_pgm])\n"
129		"	epsw	%[reg1],%[reg2]\n"
130		"	st	%[reg1],0(%[psw_pgm])\n"
131		"	st	%[reg2],4(%[psw_pgm])\n"
132		"	larl	%[reg1],1f\n"
133		"	stg	%[reg1],8(%[psw_pgm])\n"
134		"	tprot	0(%[addr]),0\n"
135		"	ipm	%[rc]\n"
136		"	srl	%[rc],28\n"
137		"1:	mvc	0(16,%[psw_pgm]),0(%[psw_old])\n"
138		: [reg1] "=&d" (reg1),
139		  [reg2] "=&a" (reg2),
140		  [rc] "+&d" (rc),
141		  "=Q" (S390_lowcore.program_new_psw.addr),
142		  "=Q" (old)
143		: [psw_old] "a" (&old),
144		  [psw_pgm] "a" (&S390_lowcore.program_new_psw),
145		  [addr] "a" (addr)
146		: "cc", "memory");
147	return rc;
148}
149
150static void search_mem_end(void)
151{
152	unsigned long range = 1 << (MAX_PHYSMEM_BITS - 20); /* in 1MB blocks */
153	unsigned long offset = 0;
154	unsigned long pivot;
155
156	while (range > 1) {
157		range >>= 1;
158		pivot = offset + range;
159		if (!tprot(pivot << 20))
160			offset = pivot;
161	}
162
163	add_mem_detect_block(0, (offset + 1) << 20);
164}
165
166unsigned long detect_memory(void)
167{
168	unsigned long max_physmem_end;
169
170	sclp_early_get_memsize(&max_physmem_end);
171
172	if (!sclp_early_read_storage_info()) {
173		mem_detect.info_source = MEM_DETECT_SCLP_STOR_INFO;
174		return max_physmem_end;
175	}
176
177	if (!diag260()) {
178		mem_detect.info_source = MEM_DETECT_DIAG260;
179		return max_physmem_end;
180	}
181
182	if (max_physmem_end) {
183		add_mem_detect_block(0, max_physmem_end);
184		mem_detect.info_source = MEM_DETECT_SCLP_READ_INFO;
185		return max_physmem_end;
186	}
187
188	search_mem_end();
189	mem_detect.info_source = MEM_DETECT_BIN_SEARCH;
190	return get_mem_detect_end();
191}