LXR linux/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
  20static int cmma_flag;
  21
  22static 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
  38void __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
  55void 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
  68void 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}
  80