arch/s390/boot/mem_detect.c

   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  */
  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
  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  */
  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
  66 static unsigned long get_mem_detect_end(void)
  67 {
  68         if (mem_detect.count)
  69                 return __get_mem_detect_block_ptr(mem_detect.count - 1)->end;
  70         return 0;
  71 }
  72
  73 static int __diag260(unsigned long rx1, unsigned long rx2)
  74 {
  75         register unsigned long _rx1 asm("2") = rx1;
  76         register unsigned long _rx2 asm("3") = rx2;
  77         register unsigned long _ry asm("4") = 0x10; /* storage configuration */
  78         int rc = -1;                                /* fail */
  79         unsigned long reg1, reg2;
  80         psw_t old = S390_lowcore.program_new_psw;
  81
  82         asm volatile(
  83                 "       epsw    %0,%1\n"
  84                 "       st      %0,%[psw_pgm]\n"
  85                 "       st      %1,%[psw_pgm]+4\n"
  86                 "       larl    %0,1f\n"
  87                 "       stg     %0,%[psw_pgm]+8\n"
  88                 "       diag    %[rx],%[ry],0x260\n"
  89                 "       ipm     %[rc]\n"
  90                 "       srl     %[rc],28\n"
  91                 "1:\n"
  92                 : "=&d" (reg1), "=&a" (reg2),
  93                   [psw_pgm] "=Q" (S390_lowcore.program_new_psw),
  94                   [rc] "+&d" (rc), [ry] "+d" (_ry)
  95                 : [rx] "d" (_rx1), "d" (_rx2)
  96                 : "cc", "memory");
  97         S390_lowcore.program_new_psw = old;
  98         return rc == 0 ? _ry : -1;
  99 }
 100
 101 static int diag260(void)
 102 {
 103         int rc, i;
 104
 105         struct {
 106                 unsigned long start;
 107                 unsigned long end;
 108         } storage_extents[8] __aligned(16); /* VM supports up to 8 extends */
 109
 110         memset(storage_extents, 0, sizeof(storage_extents));
 111         rc = __diag260((unsigned long)storage_extents, sizeof(storage_extents));
 112         if (rc == -1)
 113                 return -1;
 114
 115         for (i = 0; i < min_t(int, rc, ARRAY_SIZE(storage_extents)); i++)
 116                 add_mem_detect_block(storage_extents[i].start, storage_extents[i].end + 1);
 117         return 0;
 118 }
 119
 120 static int tprot(unsigned long addr)
 121 {
 122         unsigned long pgm_addr;
 123         int rc = -EFAULT;
 124         psw_t old = S390_lowcore.program_new_psw;
 125
 126         S390_lowcore.program_new_psw.mask = __extract_psw();
 127         asm volatile(
 128                 "       larl    %[pgm_addr],1f\n"
 129                 "       stg     %[pgm_addr],%[psw_pgm_addr]\n"
 130                 "       tprot   0(%[addr]),0\n"
 131                 "       ipm     %[rc]\n"
 132                 "       srl     %[rc],28\n"
 133                 "1:\n"
 134                 : [pgm_addr] "=&d"(pgm_addr),
 135                   [psw_pgm_addr] "=Q"(S390_lowcore.program_new_psw.addr),
 136                   [rc] "+&d"(rc)
 137                 : [addr] "a"(addr)
 138                 : "cc", "memory");
 139         S390_lowcore.program_new_psw = old;
 140         return rc;
 141 }
 142
 143 static void search_mem_end(void)
 144 {
 145         unsigned long range = 1 << (MAX_PHYSMEM_BITS - 20); /* in 1MB blocks */
 146         unsigned long offset = 0;
 147         unsigned long pivot;
 148
 149         while (range > 1) {
 150                 range >>= 1;
 151                 pivot = offset + range;
 152                 if (!tprot(pivot << 20))
 153                         offset = pivot;
 154         }
 155
 156         add_mem_detect_block(0, (offset + 1) << 20);
 157 }
 158
 159 void detect_memory(void)
 160 {
 161         sclp_early_get_memsize(&max_physmem_end);
 162
 163         if (!sclp_early_read_storage_info()) {
 164                 mem_detect.info_source = MEM_DETECT_SCLP_STOR_INFO;
 165                 return;
 166         }
 167
 168         if (!diag260()) {
 169                 mem_detect.info_source = MEM_DETECT_DIAG260;
 170                 return;
 171         }
 172
 173         if (max_physmem_end) {
 174                 add_mem_detect_block(0, max_physmem_end);
 175                 mem_detect.info_source = MEM_DETECT_SCLP_READ_INFO;
 176                 return;
 177         }
 178
 179         search_mem_end();
 180         mem_detect.info_source = MEM_DETECT_BIN_SEARCH;
 181         max_physmem_end = get_mem_detect_end();
 182 }