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 #include <asm/setup.h>
  16 #include <asm/ipl.h>
  17
  18 #define ESSA_SET_STABLE         1
  19 #define ESSA_SET_UNUSED         2
  20
  21 static int cmma_flag = 1;
  22
  23 static int __init cmma(char *str)
  24 {
  25         char *parm;
  26
  27         parm = strstrip(str);
  28         if (strcmp(parm, "yes") == 0 || strcmp(parm, "on") == 0) {
  29                 cmma_flag = 1;
  30                 return 1;
  31         }
  32         cmma_flag = 0;
  33         if (strcmp(parm, "no") == 0 || strcmp(parm, "off") == 0)
  34                 return 1;
  35         return 0;
  36 }
  37 __setup("cmma=", cmma);
  38
  39 void __init cmma_init(void)
  40 {
  41         register unsigned long tmp asm("0") = 0;
  42         register int rc asm("1") = -EOPNOTSUPP;
  43
  44         if (!cmma_flag)
  45                 return;
  46         /*
  47          * Disable CMM for dump, otherwise  the tprot based memory
  48          * detection can fail because of unstable pages.
  49          */
  50         if (OLDMEM_BASE || ipl_info.type == IPL_TYPE_FCP_DUMP) {
  51                 cmma_flag = 0;
  52                 return;
  53         }
  54         asm volatile(
  55                 "       .insn rrf,0xb9ab0000,%1,%1,0,0\n"
  56                 "0:     la      %0,0\n"
  57                 "1:\n"
  58                 EX_TABLE(0b,1b)
  59                 : "+&d" (rc), "+&d" (tmp));
  60         if (rc)
  61                 cmma_flag = 0;
  62 }
  63
  64 static inline void set_page_unstable(struct page *page, int order)
  65 {
  66         int i, rc;
  67
  68         for (i = 0; i < (1 << order); i++)
  69                 asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
  70                              : "=&d" (rc)
  71                              : "a" (page_to_phys(page + i)),
  72                                "i" (ESSA_SET_UNUSED));
  73 }
  74
  75 void arch_free_page(struct page *page, int order)
  76 {
  77         if (!cmma_flag)
  78                 return;
  79         set_page_unstable(page, order);
  80 }
  81
  82 static inline void set_page_stable(struct page *page, int order)
  83 {
  84         int i, rc;
  85
  86         for (i = 0; i < (1 << order); i++)
  87                 asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
  88                              : "=&d" (rc)
  89                              : "a" (page_to_phys(page + i)),
  90                                "i" (ESSA_SET_STABLE));
  91 }
  92
  93 void arch_alloc_page(struct page *page, int order)
  94 {
  95         if (!cmma_flag)
  96                 return;
  97         set_page_stable(page, order);
  98 }
  99
 100 void arch_set_page_states(int make_stable)
 101 {
 102         unsigned long flags, order, t;
 103         struct list_head *l;
 104         struct page *page;
 105         struct zone *zone;
 106
 107         if (!cmma_flag)
 108                 return;
 109         if (make_stable)
 110                 drain_local_pages(NULL);
 111         for_each_populated_zone(zone) {
 112                 spin_lock_irqsave(&zone->lock, flags);
 113                 for_each_migratetype_order(order, t) {
 114                         list_for_each(l, &zone->free_area[order].free_list[t]) {
 115                                 page = list_entry(l, struct page, lru);
 116                                 if (make_stable)
 117                                         set_page_stable(page, order);
 118                                 else
 119                                         set_page_unstable(page, order);
 120                         }
 121                 }
 122                 spin_unlock_irqrestore(&zone->lock, flags);
 123         }
 124 }