root/arch/s390/boot/mem_detect.c

DEFINITIONS

1. __get_mem_detect_block_ptr
2. add_mem_detect_block
3. __diag260
4. diag260
5. tprot
6. search_mem_end
7. detect_memory

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