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/gfp.h>
  14 #include <linux/init.h>
  15
  16 #include <asm/page-states.h>
  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 static inline int cmma_test_essa(void)
  37 {
  38         register unsigned long tmp asm("0") = 0;
  39         register int rc asm("1") = -EOPNOTSUPP;
  40
  41         asm volatile(
  42                 "       .insn rrf,0xb9ab0000,%1,%1,0,0\n"
  43                 "0:     la      %0,0\n"
  44                 "1:\n"
  45                 EX_TABLE(0b,1b)
  46                 : "+&d" (rc), "+&d" (tmp));
  47         return rc;
  48 }
  49
  50 void __init cmma_init(void)
  51 {
  52         if (!cmma_flag)
  53                 return;
  54         if (cmma_test_essa())
  55                 cmma_flag = 0;
  56 }
  57
  58 static inline void set_page_unstable(struct page *page, int order)
  59 {
  60         int i, rc;
  61
  62         for (i = 0; i < (1 << order); i++)
  63                 asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
  64                              : "=&d" (rc)
  65                              : "a" (page_to_phys(page + i)),
  66                                "i" (ESSA_SET_UNUSED));
  67 }
  68
  69 void arch_free_page(struct page *page, int order)
  70 {
  71         if (!cmma_flag)
  72                 return;
  73         set_page_unstable(page, order);
  74 }
  75
  76 static inline void set_page_stable(struct page *page, int order)
  77 {
  78         int i, rc;
  79
  80         for (i = 0; i < (1 << order); i++)
  81                 asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
  82                              : "=&d" (rc)
  83                              : "a" (page_to_phys(page + i)),
  84                                "i" (ESSA_SET_STABLE));
  85 }
  86
  87 void arch_alloc_page(struct page *page, int order)
  88 {
  89         if (!cmma_flag)
  90                 return;
  91         set_page_stable(page, order);
  92 }
  93
  94 void arch_set_page_states(int make_stable)
  95 {
  96         unsigned long flags, order, t;
  97         struct list_head *l;
  98         struct page *page;
  99         struct zone *zone;
 100
 101         if (!cmma_flag)
 102                 return;
 103         if (make_stable)
 104                 drain_local_pages(NULL);
 105         for_each_populated_zone(zone) {
 106                 spin_lock_irqsave(&zone->lock, flags);
 107                 for_each_migratetype_order(order, t) {
 108                         list_for_each(l, &zone->free_area[order].free_list[t]) {
 109                                 page = list_entry(l, struct page, lru);
 110                                 if (make_stable)
 111                                         set_page_stable(page, order);
 112                                 else
 113                                         set_page_unstable(page, order);
 114                         }
 115                 }
 116                 spin_unlock_irqrestore(&zone->lock, flags);
 117         }
 118 }