page-states.c

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/*
 * Copyright IBM Corp. 2008
 *
 * Guest page hinting for unused pages.
 *
 * Author(s): Martin Schwidefsky <[email protected]>
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/gfp.h>
#include <linux/init.h>

#define ESSA_SET_STABLE     1
#define ESSA_SET_UNUSED     2

static int cmma_flag = 1;

static int __init cmma(char *str)
{
    char *parm;

    parm = strstrip(str);
    if (strcmp(parm, "yes") == 0 || strcmp(parm, "on") == 0) {
        cmma_flag = 1;
        return 1;
    }
    cmma_flag = 0;
    if (strcmp(parm, "no") == 0 || strcmp(parm, "off") == 0)
        return 1;
    return 0;
}
__setup("cmma=", cmma);

void __init cmma_init(void)
{
    register unsigned long tmp asm("0") = 0;
    register int rc asm("1") = -EOPNOTSUPP;

    if (!cmma_flag)
        return;
    asm volatile(
        "       .insn rrf,0xb9ab0000,%1,%1,0,0\n"
        "0:     la      %0,0\n"
        "1:\n"
        EX_TABLE(0b,1b)
        : "+&d" (rc), "+&d" (tmp));
    if (rc)
        cmma_flag = 0;
}

static inline void set_page_unstable(struct page *page, int order)
{
    int i, rc;

    for (i = 0; i < (1 << order); i++)
        asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
                 : "=&d" (rc)
                 : "a" (page_to_phys(page + i)),
                   "i" (ESSA_SET_UNUSED));
}

void arch_free_page(struct page *page, int order)
{
    if (!cmma_flag)
        return;
    set_page_unstable(page, order);
}

static inline void set_page_stable(struct page *page, int order)
{
    int i, rc;

    for (i = 0; i < (1 << order); i++)
        asm volatile(".insn rrf,0xb9ab0000,%0,%1,%2,0"
                 : "=&d" (rc)
                 : "a" (page_to_phys(page + i)),
                   "i" (ESSA_SET_STABLE));
}

void arch_alloc_page(struct page *page, int order)
{
    if (!cmma_flag)
        return;
    set_page_stable(page, order);
}

void arch_set_page_states(int make_stable)
{
    unsigned long flags, order, t;
    struct list_head *l;
    struct page *page;
    struct zone *zone;

    if (!cmma_flag)
        return;
    if (make_stable)
        drain_local_pages(NULL);
    for_each_populated_zone(zone) {
        spin_lock_irqsave(&zone->lock, flags);
        for_each_migratetype_order(order, t) {
            list_for_each(l, &zone->free_area[order].free_list[t]) {
                page = list_entry(l, struct page, lru);
                if (make_stable)
                    set_page_stable(page, order);
                else
                    set_page_unstable(page, order);
            }
        }
        spin_unlock_irqrestore(&zone->lock, flags);
    }
}