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 #define ESSA_SET_STABLE         1
  17 #define ESSA_SET_UNUSED         2
  18
  19 static int cmma_flag = 1;
  20
  21 static int __init cmma(char *str)
  22 {
  23         char *parm;
  24
  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 __setup("cmma=", cmma);
  36
  37 void __init cmma_init(void)
  38 {
  39         register unsigned long tmp asm("0") = 0;
  40         register int rc asm("1") = -EOPNOTSUPP;
  41
  42         if (!cmma_flag)
  43                 return;
  44         asm volatile(
  45                 "       .insn rrf,0xb9ab0000,%1,%1,0,0\n"
  46                 "0:     la      %0,0\n"
  47                 "1:\n"
  48                 EX_TABLE(0b,1b)
  49                 : "+&d" (rc), "+&d" (tmp));
  50         if (rc)
  51                 cmma_flag = 0;
  52 }
  53
  54 static inline void set_page_unstable(struct page *page, int order)
  55 {
  56         int i, rc;
  57
  58         for (i = 0; i < (1 << order); i++)
  59                 asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
  60                              : "=&d" (rc)
  61                              : "a" (page_to_phys(page + i)),
  62                                "i" (ESSA_SET_UNUSED));
  63 }
  64
  65 void arch_free_page(struct page *page, int order)
  66 {
  67         if (!cmma_flag)
  68                 return;
  69         set_page_unstable(page, order);
  70 }
  71
  72 static inline void set_page_stable(struct page *page, int order)
  73 {
  74         int i, rc;
  75
  76         for (i = 0; i < (1 << order); i++)
  77                 asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
  78                              : "=&d" (rc)
  79                              : "a" (page_to_phys(page + i)),
  80                                "i" (ESSA_SET_STABLE));
  81 }
  82
  83 void arch_alloc_page(struct page *page, int order)
  84 {
  85         if (!cmma_flag)
  86                 return;
  87         set_page_stable(page, order);
  88 }
  89
  90 void arch_set_page_states(int make_stable)
  91 {
  92         unsigned long flags, order, t;
  93         struct list_head *l;
  94         struct page *page;
  95         struct zone *zone;
  96
  97         if (!cmma_flag)
  98                 return;
  99         if (make_stable)
 100                 drain_local_pages(NULL);
 101         for_each_populated_zone(zone) {
 102                 spin_lock_irqsave(&zone->lock, flags);
 103                 for_each_migratetype_order(order, t) {
 104                         list_for_each(l, &zone->free_area[order].free_list[t]) {
 105                                 page = list_entry(l, struct page, lru);
 106                                 if (make_stable)
 107                                         set_page_stable(page, order);
 108                                 else
 109                                         set_page_unstable(page, order);
 110                         }
 111                 }
 112                 spin_unlock_irqrestore(&zone->lock, flags);
 113         }
 114 }