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authorGerald Schaefer <geraldsc@de.ibm.com>2008-04-30 13:38:46 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2008-04-30 13:38:47 +0200
commit53492b1de46a7576170e865062ffcfc93bb5650b (patch)
treebee94e5b2e8c19c1a094a25023cb82572707feb4 /arch/s390/mm/hugetlbpage.c
parent2e5061e40af88070984e3769eafb5a06022375fd (diff)
downloadlinux-linaro-stable-53492b1de46a7576170e865062ffcfc93bb5650b.tar.gz
[S390] System z large page support.
This adds hugetlbfs support on System z, using both hardware large page support if available and software large page emulation on older hardware. Shared (large) page tables are implemented in software emulation mode, by using page->index of the first tail page from a compound large page to store page table information. Signed-off-by: Gerald Schaefer <geraldsc@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/mm/hugetlbpage.c')
-rw-r--r--arch/s390/mm/hugetlbpage.c134
1 files changed, 134 insertions, 0 deletions
diff --git a/arch/s390/mm/hugetlbpage.c b/arch/s390/mm/hugetlbpage.c
new file mode 100644
index 000000000000..f4b6124fdb75
--- /dev/null
+++ b/arch/s390/mm/hugetlbpage.c
@@ -0,0 +1,134 @@
+/*
+ * IBM System z Huge TLB Page Support for Kernel.
+ *
+ * Copyright 2007 IBM Corp.
+ * Author(s): Gerald Schaefer <gerald.schaefer@de.ibm.com>
+ */
+
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+
+
+void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
+ pte_t *pteptr, pte_t pteval)
+{
+ pmd_t *pmdp = (pmd_t *) pteptr;
+ pte_t shadow_pteval = pteval;
+ unsigned long mask;
+
+ if (!MACHINE_HAS_HPAGE) {
+ pteptr = (pte_t *) pte_page(pteval)[1].index;
+ mask = pte_val(pteval) &
+ (_SEGMENT_ENTRY_INV | _SEGMENT_ENTRY_RO);
+ pte_val(pteval) = (_SEGMENT_ENTRY + __pa(pteptr)) | mask;
+ if (mm->context.noexec) {
+ pteptr += PTRS_PER_PTE;
+ pte_val(shadow_pteval) =
+ (_SEGMENT_ENTRY + __pa(pteptr)) | mask;
+ }
+ }
+
+ pmd_val(*pmdp) = pte_val(pteval);
+ if (mm->context.noexec) {
+ pmdp = get_shadow_table(pmdp);
+ pmd_val(*pmdp) = pte_val(shadow_pteval);
+ }
+}
+
+int arch_prepare_hugepage(struct page *page)
+{
+ unsigned long addr = page_to_phys(page);
+ pte_t pte;
+ pte_t *ptep;
+ int i;
+
+ if (MACHINE_HAS_HPAGE)
+ return 0;
+
+ ptep = (pte_t *) pte_alloc_one(&init_mm, address);
+ if (!ptep)
+ return -ENOMEM;
+
+ pte = mk_pte(page, PAGE_RW);
+ for (i = 0; i < PTRS_PER_PTE; i++) {
+ set_pte_at(&init_mm, addr + i * PAGE_SIZE, ptep + i, pte);
+ pte_val(pte) += PAGE_SIZE;
+ }
+ page[1].index = (unsigned long) ptep;
+ return 0;
+}
+
+void arch_release_hugepage(struct page *page)
+{
+ pte_t *ptep;
+
+ if (MACHINE_HAS_HPAGE)
+ return;
+
+ ptep = (pte_t *) page[1].index;
+ if (!ptep)
+ return;
+ pte_free(&init_mm, ptep);
+ page[1].index = 0;
+}
+
+pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr)
+{
+ pgd_t *pgdp;
+ pud_t *pudp;
+ pmd_t *pmdp = NULL;
+
+ pgdp = pgd_offset(mm, addr);
+ pudp = pud_alloc(mm, pgdp, addr);
+ if (pudp)
+ pmdp = pmd_alloc(mm, pudp, addr);
+ return (pte_t *) pmdp;
+}
+
+pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
+{
+ pgd_t *pgdp;
+ pud_t *pudp;
+ pmd_t *pmdp = NULL;
+
+ pgdp = pgd_offset(mm, addr);
+ if (pgd_present(*pgdp)) {
+ pudp = pud_offset(pgdp, addr);
+ if (pud_present(*pudp))
+ pmdp = pmd_offset(pudp, addr);
+ }
+ return (pte_t *) pmdp;
+}
+
+int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
+{
+ return 0;
+}
+
+struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address,
+ int write)
+{
+ return ERR_PTR(-EINVAL);
+}
+
+int pmd_huge(pmd_t pmd)
+{
+ if (!MACHINE_HAS_HPAGE)
+ return 0;
+
+ return !!(pmd_val(pmd) & _SEGMENT_ENTRY_LARGE);
+}
+
+struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
+ pmd_t *pmdp, int write)
+{
+ struct page *page;
+
+ if (!MACHINE_HAS_HPAGE)
+ return NULL;
+
+ page = pmd_page(*pmdp);
+ if (page)
+ page += ((address & ~HPAGE_MASK) >> PAGE_SHIFT);
+ return page;
+}