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 static inline int cmma_test_essa(void)
  38 {
  39         register unsigned long tmp asm("0") = 0;
  40         register int rc asm("1") = -EOPNOTSUPP;
  41
  42         asm volatile(
  43                 "       .insn rrf,0xb9ab0000,%1,%1,0,0\n"
  44                 "0:     la      %0,0\n"
  45                 "1:\n"
  46                 EX_TABLE(0b,1b)
  47                 : "+&d" (rc), "+&d" (tmp));
  48         return rc;
  49 }
  50
  51 void __init cmma_init(void)
  52 {
  53         if (!cmma_flag)
  54                 return;
  55         if (cmma_test_essa())
  56                 cmma_flag = 0;
  57 }
  58
  59 static inline void set_page_unstable(struct page *page, int order)
  60 {
  61         int i, rc;
  62
  63         for (i = 0; i < (1 << order); i++)
  64                 asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
  65                              : "=&d" (rc)
  66                              : "a" (page_to_phys(page + i)),
  67                                "i" (ESSA_SET_UNUSED));
  68 }
  69
  70 void arch_free_page(struct page *page, int order)
  71 {
  72         if (!cmma_flag)
  73                 return;
  74         set_page_unstable(page, order);
  75 }
  76
  77 static inline void set_page_stable(struct page *page, int order)
  78 {
  79         int i, rc;
  80
  81         for (i = 0; i < (1 << order); i++)
  82                 asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
  83                              : "=&d" (rc)
  84                              : "a" (page_to_phys(page + i)),
  85                                "i" (ESSA_SET_STABLE));
  86 }
  87
  88 void arch_alloc_page(struct page *page, int order)
  89 {
  90         if (!cmma_flag)
  91                 return;
  92         set_page_stable(page, order);
  93 }
  94
  95 void arch_set_page_states(int make_stable)
  96 {
  97         unsigned long flags, order, t;
  98         struct list_head *l;
  99         struct page *page;
 100         struct zone *zone;
 101
 102         if (!cmma_flag)
 103                 return;
 104         if (make_stable)
 105                 drain_local_pages(NULL);
 106         for_each_populated_zone(zone) {
 107                 spin_lock_irqsave(&zone->lock, flags);
 108                 for_each_migratetype_order(order, t) {
 109                         list_for_each(l, &zone->free_area[order].free_list[t]) {
 110                                 page = list_entry(l, struct page, lru);
 111                                 if (make_stable)
 112                                         set_page_stable(page, order);
 113                                 else
 114                                         set_page_unstable(page, order);
 115                         }
 116                 }
 117                 spin_unlock_irqrestore(&zone->lock, flags);
 118         }
 119 }