arch/s390/mm/page-states.c

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