arch/s390/kernel/mem_detect.c

   1 /*
   2  *    Copyright IBM Corp. 2008
   3  *    Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
   4  */
   5
   6 #include <linux/kernel.h>
   7 #include <linux/module.h>
   8 #include <asm/ipl.h>
   9 #include <asm/sclp.h>
  10 #include <asm/setup.h>
  11
  12 static inline int tprot(unsigned long addr)
  13 {
  14         int rc = -EFAULT;
  15
  16         asm volatile(
  17                 "       tprot   0(%1),0\n"
  18                 "0:     ipm     %0\n"
  19                 "       srl     %0,28\n"
  20                 "1:\n"
  21                 EX_TABLE(0b,1b)
  22                 : "+d" (rc) : "a" (addr) : "cc");
  23         return rc;
  24 }
  25
  26 #define ADDR2G (1ULL << 31)
  27
  28 static void find_memory_chunks(struct mem_chunk chunk[])
  29 {
  30         unsigned long long memsize, rnmax, rzm;
  31         unsigned long addr = 0, size;
  32         int i = 0, type;
  33
  34         rzm = sclp_get_rzm();
  35         rnmax = sclp_get_rnmax();
  36         memsize = rzm * rnmax;
  37         if (!rzm)
  38                 rzm = 1ULL << 17;
  39         if (sizeof(long) == 4) {
  40                 rzm = min(ADDR2G, rzm);
  41                 memsize = memsize ? min(ADDR2G, memsize) : ADDR2G;
  42         }
  43         do {
  44                 size = 0;
  45                 type = tprot(addr);
  46                 do {
  47                         size += rzm;
  48                         if (memsize && addr + size >= memsize)
  49                                 break;
  50                 } while (type == tprot(addr + size));
  51                 if (type == CHUNK_READ_WRITE || type == CHUNK_READ_ONLY) {
  52                         chunk[i].addr = addr;
  53                         chunk[i].size = size;
  54                         chunk[i].type = type;
  55                         i++;
  56                 }
  57                 addr += size;
  58         } while (addr < memsize && i < MEMORY_CHUNKS);
  59 }
  60
  61 void detect_memory_layout(struct mem_chunk chunk[])
  62 {
  63         unsigned long flags, cr0;
  64
  65         memset(chunk, 0, MEMORY_CHUNKS * sizeof(struct mem_chunk));
  66         /* Disable IRQs, DAT and low address protection so tprot does the
  67          * right thing and we don't get scheduled away with low address
  68          * protection disabled.
  69          */
  70         flags = __raw_local_irq_stnsm(0xf8);
  71         __ctl_store(cr0, 0, 0);
  72         __ctl_clear_bit(0, 28);
  73         find_memory_chunks(chunk);
  74         __ctl_load(cr0, 0, 0);
  75         __raw_local_irq_ssm(flags);
  76 }
  77 EXPORT_SYMBOL(detect_memory_layout);