linux/arch/s390/kernel/mem_detect.c
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   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
  12static 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
  28static 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
  61void 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}
  77EXPORT_SYMBOL(detect_memory_layout);
  78