arch/s390/mm/page-states.c

   1 /*
   2  * arch/s390/mm/page-states.c
   3  *
   4  * Copyright IBM Corp. 2008
   5  *
   6  * Guest page hinting for unused pages.
   7  *
   8  * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/errno.h>
  13 #include <linux/types.h>
  14 #include <linux/mm.h>
  15 #include <linux/init.h>
  16
  17 #define ESSA_SET_STABLE         1
  18 #define ESSA_SET_UNUSED         2
  19
  20 static int cmma_flag;
  21
  22 static int __init cmma(char *str)
  23 {
  24         char *parm;
  25         parm = strstrip(str);
  26         if (strcmp(parm, "yes") == 0 || strcmp(parm, "on") == 0) {
  27                 cmma_flag = 1;
  28                 return 1;
  29         }
  30         cmma_flag = 0;
  31         if (strcmp(parm, "no") == 0 || strcmp(parm, "off") == 0)
  32                 return 1;
  33         return 0;
  34 }
  35
  36 __setup("cmma=", cmma);
  37
  38 void __init cmma_init(void)
  39 {
  40         register unsigned long tmp asm("0") = 0;
  41         register int rc asm("1") = -EOPNOTSUPP;
  42
  43         if (!cmma_flag)
  44                 return;
  45         asm volatile(
  46                 "       .insn rrf,0xb9ab0000,%1,%1,0,0\n"
  47                 "0:     la      %0,0\n"
  48                 "1:\n"
  49                 EX_TABLE(0b,1b)
  50                 : "+&d" (rc), "+&d" (tmp));
  51         if (rc)
  52                 cmma_flag = 0;
  53 }
  54
  55 void arch_free_page(struct page *page, int order)
  56 {
  57         int i, rc;
  58
  59         if (!cmma_flag)
  60                 return;
  61         for (i = 0; i < (1 << order); i++)
  62                 asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
  63                              : "=&d" (rc)
  64                              : "a" ((page_to_pfn(page) + i) << PAGE_SHIFT),
  65                                "i" (ESSA_SET_UNUSED));
  66 }
  67
  68 void arch_alloc_page(struct page *page, int order)
  69 {
  70         int i, rc;
  71
  72         if (!cmma_flag)
  73                 return;
  74         for (i = 0; i < (1 << order); i++)
  75                 asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
  76                              : "=&d" (rc)
  77                              : "a" ((page_to_pfn(page) + i) << PAGE_SHIFT),
  78                                "i" (ESSA_SET_STABLE));
  79 }