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 struct 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  */
  23 static 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
  34 static 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  */
  47 void 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
  65 static 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
 100 static 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
 119 static 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
 148 static 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
 164 unsigned 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 }