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/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
  13 struct 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 static struct mem_detect_block *__get_mem_detect_block_ptr(u32 n)
  20 {
  21         if (n < MEM_INLINED_ENTRIES)
  22                 return &mem_detect.entries[n];
  23         return &mem_detect.entries_extended[n - MEM_INLINED_ENTRIES];
  24 }
  25
  26 /*
  27  * sequential calls to add_mem_detect_block with adjacent memory areas
  28  * are merged together into single memory block.
  29  */
  30 void add_mem_detect_block(u64 start, u64 end)
  31 {
  32         struct mem_detect_block *block;
  33
  34         if (mem_detect.count) {
  35                 block = __get_mem_detect_block_ptr(mem_detect.count - 1);
  36                 if (block->end == start) {
  37                         block->end = end;
  38                         return;
  39                 }
  40         }
  41
  42         block = __get_mem_detect_block_ptr(mem_detect.count);
  43         block->start = start;
  44         block->end = end;
  45         mem_detect.count++;
  46 }
  47
  48 static int __diag260(unsigned long rx1, unsigned long rx2)
  49 {
  50         unsigned long reg1, reg2, ry;
  51         union register_pair rx;
  52         psw_t old;
  53         int rc;
  54
  55         rx.even = rx1;
  56         rx.odd  = rx2;
  57         ry = 0x10; /* storage configuration */
  58         rc = -1;   /* fail */
  59         asm volatile(
  60                 "       mvc     0(16,%[psw_old]),0(%[psw_pgm])\n"
  61                 "       epsw    %[reg1],%[reg2]\n"
  62                 "       st      %[reg1],0(%[psw_pgm])\n"
  63                 "       st      %[reg2],4(%[psw_pgm])\n"
  64                 "       larl    %[reg1],1f\n"
  65                 "       stg     %[reg1],8(%[psw_pgm])\n"
  66                 "       diag    %[rx],%[ry],0x260\n"
  67                 "       ipm     %[rc]\n"
  68                 "       srl     %[rc],28\n"
  69                 "1:     mvc     0(16,%[psw_pgm]),0(%[psw_old])\n"
  70                 : [reg1] "=&d" (reg1),
  71                   [reg2] "=&a" (reg2),
  72                   [rc] "+&d" (rc),
  73                   [ry] "+&d" (ry),
  74                   "+Q" (S390_lowcore.program_new_psw),
  75                   "=Q" (old)
  76                 : [rx] "d" (rx.pair),
  77                   [psw_old] "a" (&old),
  78                   [psw_pgm] "a" (&S390_lowcore.program_new_psw)
  79                 : "cc", "memory");
  80         return rc == 0 ? ry : -1;
  81 }
  82
  83 static int diag260(void)
  84 {
  85         int rc, i;
  86
  87         struct {
  88                 unsigned long start;
  89                 unsigned long end;
  90         } storage_extents[8] __aligned(16); /* VM supports up to 8 extends */
  91
  92         memset(storage_extents, 0, sizeof(storage_extents));
  93         rc = __diag260((unsigned long)storage_extents, sizeof(storage_extents));
  94         if (rc == -1)
  95                 return -1;
  96
  97         for (i = 0; i < min_t(int, rc, ARRAY_SIZE(storage_extents)); i++)
  98                 add_mem_detect_block(storage_extents[i].start, storage_extents[i].end + 1);
  99         return 0;
 100 }
 101
 102 static int tprot(unsigned long addr)
 103 {
 104         unsigned long reg1, reg2;
 105         int rc = -EFAULT;
 106         psw_t old;
 107
 108         asm volatile(
 109                 "       mvc     0(16,%[psw_old]),0(%[psw_pgm])\n"
 110                 "       epsw    %[reg1],%[reg2]\n"
 111                 "       st      %[reg1],0(%[psw_pgm])\n"
 112                 "       st      %[reg2],4(%[psw_pgm])\n"
 113                 "       larl    %[reg1],1f\n"
 114                 "       stg     %[reg1],8(%[psw_pgm])\n"
 115                 "       tprot   0(%[addr]),0\n"
 116                 "       ipm     %[rc]\n"
 117                 "       srl     %[rc],28\n"
 118                 "1:     mvc     0(16,%[psw_pgm]),0(%[psw_old])\n"
 119                 : [reg1] "=&d" (reg1),
 120                   [reg2] "=&a" (reg2),
 121                   [rc] "+&d" (rc),
 122                   "=Q" (S390_lowcore.program_new_psw.addr),
 123                   "=Q" (old)
 124                 : [psw_old] "a" (&old),
 125                   [psw_pgm] "a" (&S390_lowcore.program_new_psw),
 126                   [addr] "a" (addr)
 127                 : "cc", "memory");
 128         return rc;
 129 }
 130
 131 static unsigned long search_mem_end(void)
 132 {
 133         unsigned long range = 1 << (MAX_PHYSMEM_BITS - 20); /* in 1MB blocks */
 134         unsigned long offset = 0;
 135         unsigned long pivot;
 136
 137         while (range > 1) {
 138                 range >>= 1;
 139                 pivot = offset + range;
 140                 if (!tprot(pivot << 20))
 141                         offset = pivot;
 142         }
 143         return (offset + 1) << 20;
 144 }
 145
 146 unsigned long detect_memory(unsigned long *safe_addr)
 147 {
 148         unsigned long max_physmem_end = 0;
 149
 150         sclp_early_get_memsize(&max_physmem_end);
 151         mem_detect.entries_extended = (struct mem_detect_block *)ALIGN(*safe_addr, sizeof(u64));
 152
 153         if (!sclp_early_read_storage_info()) {
 154                 mem_detect.info_source = MEM_DETECT_SCLP_STOR_INFO;
 155         } else if (!diag260()) {
 156                 mem_detect.info_source = MEM_DETECT_DIAG260;
 157                 max_physmem_end = max_physmem_end ?: get_mem_detect_end();
 158         } else if (max_physmem_end) {
 159                 add_mem_detect_block(0, max_physmem_end);
 160                 mem_detect.info_source = MEM_DETECT_SCLP_READ_INFO;
 161         } else {
 162                 max_physmem_end = search_mem_end();
 163                 add_mem_detect_block(0, max_physmem_end);
 164                 mem_detect.info_source = MEM_DETECT_BIN_SEARCH;
 165         }
 166
 167         if (mem_detect.count > MEM_INLINED_ENTRIES) {
 168                 *safe_addr += (mem_detect.count - MEM_INLINED_ENTRIES) *
 169                              sizeof(struct mem_detect_block);
 170         }
 171
 172         return max_physmem_end;
 173 }