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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright IBM Corp. 2008
*
* Guest page hinting for unused pages.
*
* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
*/
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/memblock.h>
#include <linux/gfp.h>
#include <linux/init.h>
#include <asm/asm-extable.h>
#include <asm/facility.h>
#include <asm/page-states.h>
static int cmma_flag = 1;
static int __init cmma(char *str)
{
bool enabled;
if (!kstrtobool(str, &enabled))
cmma_flag = enabled;
return 1;
}
__setup("cmma=", cmma);
static inline int cmma_test_essa(void)
{
unsigned long tmp = 0;
int rc = -EOPNOTSUPP;
/* test ESSA_GET_STATE */
asm volatile(
" .insn rrf,0xb9ab0000,%[tmp],%[tmp],%[cmd],0\n"
"0: la %[rc],0\n"
"1:\n"
EX_TABLE(0b, 1b)
: [rc] "+&d" (rc), [tmp] "+&d" (tmp)
: [cmd] "i" (ESSA_GET_STATE));
return rc;
}
void __init cmma_init(void)
{
if (!cmma_flag)
return;
if (cmma_test_essa()) {
cmma_flag = 0;
return;
}
if (test_facility(147))
cmma_flag = 2;
}
static __always_inline void essa(unsigned long paddr, unsigned char cmd)
{
unsigned long rc;
asm volatile(
" .insn rrf,0xb9ab0000,%[rc],%[paddr],%[cmd],0"
: [rc] "=d" (rc)
: [paddr] "d" (paddr),
[cmd] "i" (cmd));
}
static __always_inline void __set_page_state(struct page *page, int order, unsigned char cmd)
{
unsigned long paddr = page_to_phys(page);
unsigned long num_pages = 1UL << order;
while (num_pages--) {
essa(paddr, cmd);
paddr += PAGE_SIZE;
}
}
static inline void set_page_unused(struct page *page, int order)
{
__set_page_state(page, order, ESSA_SET_UNUSED);
}
static inline void set_page_stable_dat(struct page *page, int order)
{
__set_page_state(page, order, ESSA_SET_STABLE);
}
static inline void set_page_stable_nodat(struct page *page, int order)
{
__set_page_state(page, order, ESSA_SET_STABLE_NODAT);
}
static void mark_kernel_pmd(pud_t *pud, unsigned long addr, unsigned long end)
{
unsigned long next;
struct page *page;
pmd_t *pmd;
pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
if (pmd_none(*pmd) || pmd_large(*pmd))
continue;
page = phys_to_page(pmd_val(*pmd));
set_bit(PG_arch_1, &page->flags);
} while (pmd++, addr = next, addr != end);
}
static void mark_kernel_pud(p4d_t *p4d, unsigned long addr, unsigned long end)
{
unsigned long next;
struct page *page;
pud_t *pud;
int i;
pud = pud_offset(p4d, addr);
do {
next = pud_addr_end(addr, end);
if (pud_none(*pud) || pud_large(*pud))
continue;
if (!pud_folded(*pud)) {
page = phys_to_page(pud_val(*pud));
for (i = 0; i < 4; i++)
set_bit(PG_arch_1, &page[i].flags);
}
mark_kernel_pmd(pud, addr, next);
} while (pud++, addr = next, addr != end);
}
static void mark_kernel_p4d(pgd_t *pgd, unsigned long addr, unsigned long end)
{
unsigned long next;
struct page *page;
p4d_t *p4d;
int i;
p4d = p4d_offset(pgd, addr);
do {
next = p4d_addr_end(addr, end);
if (p4d_none(*p4d))
continue;
if (!p4d_folded(*p4d)) {
page = phys_to_page(p4d_val(*p4d));
for (i = 0; i < 4; i++)
set_bit(PG_arch_1, &page[i].flags);
}
mark_kernel_pud(p4d, addr, next);
} while (p4d++, addr = next, addr != end);
}
static void mark_kernel_pgd(void)
{
unsigned long addr, next, max_addr;
struct page *page;
pgd_t *pgd;
int i;
addr = 0;
/*
* Figure out maximum virtual address accessible with the
* kernel ASCE. This is required to keep the page table walker
* from accessing non-existent entries.
*/
max_addr = (S390_lowcore.kernel_asce.val & _ASCE_TYPE_MASK) >> 2;
max_addr = 1UL << (max_addr * 11 + 31);
pgd = pgd_offset_k(addr);
do {
next = pgd_addr_end(addr, max_addr);
if (pgd_none(*pgd))
continue;
if (!pgd_folded(*pgd)) {
page = phys_to_page(pgd_val(*pgd));
for (i = 0; i < 4; i++)
set_bit(PG_arch_1, &page[i].flags);
}
mark_kernel_p4d(pgd, addr, next);
} while (pgd++, addr = next, addr != max_addr);
}
void __init cmma_init_nodat(void)
{
struct page *page;
unsigned long start, end, ix;
int i;
if (cmma_flag < 2)
return;
/* Mark pages used in kernel page tables */
mark_kernel_pgd();
page = virt_to_page(&swapper_pg_dir);
for (i = 0; i < 4; i++)
set_bit(PG_arch_1, &page[i].flags);
page = virt_to_page(&invalid_pg_dir);
for (i = 0; i < 4; i++)
set_bit(PG_arch_1, &page[i].flags);
/* Set all kernel pages not used for page tables to stable/no-dat */
for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, NULL) {
page = pfn_to_page(start);
for (ix = start; ix < end; ix++, page++) {
if (__test_and_clear_bit(PG_arch_1, &page->flags))
continue; /* skip page table pages */
if (!list_empty(&page->lru))
continue; /* skip free pages */
set_page_stable_nodat(page, 0);
}
}
}
void arch_free_page(struct page *page, int order)
{
if (!cmma_flag)
return;
set_page_unused(page, order);
}
void arch_alloc_page(struct page *page, int order)
{
if (!cmma_flag)
return;
if (cmma_flag < 2)
set_page_stable_dat(page, order);
else
set_page_stable_nodat(page, order);
}
void arch_set_page_dat(struct page *page, int order)
{
if (!cmma_flag)
return;
set_page_stable_dat(page, order);
}
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