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![Heiko Carstens](/assets/img/avatar_default.png)
On s390 __ro_after_init is currently mapped to __read_mostly which means that data marked as __ro_after_init will not be protected. Reason for this is that the common code __ro_after_init implementation is x86 centric: the ro_after_init data section was added to rodata, since x86 enables write protection to kernel text and rodata very late. On s390 we have write protection for these sections enabled with the initial page tables. So adding the ro_after_init data section to rodata does not work on s390. In order to make __ro_after_init work properly on s390 move the ro_after_init data, right behind rodata. Unlike the rodata section it will be marked read-only later after all init calls happened. This s390 specific implementation adds new __start_ro_after_init and __end_ro_after_init labels. Everything in between will be marked read-only after the init calls happened. In addition to the __ro_after_init data move also the exception table there, since from a practical point of view it fits the __ro_after_init requirements. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
407 lines
9 KiB
C
407 lines
9 KiB
C
/*
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* Copyright IBM Corp. 2006
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* Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
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*/
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#include <linux/bootmem.h>
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#include <linux/pfn.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/list.h>
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#include <linux/hugetlb.h>
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#include <linux/slab.h>
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#include <linux/memblock.h>
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#include <asm/cacheflush.h>
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#include <asm/pgalloc.h>
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#include <asm/pgtable.h>
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#include <asm/setup.h>
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#include <asm/tlbflush.h>
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#include <asm/sections.h>
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static DEFINE_MUTEX(vmem_mutex);
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struct memory_segment {
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struct list_head list;
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unsigned long start;
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unsigned long size;
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};
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static LIST_HEAD(mem_segs);
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static void __ref *vmem_alloc_pages(unsigned int order)
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{
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unsigned long size = PAGE_SIZE << order;
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if (slab_is_available())
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return (void *)__get_free_pages(GFP_KERNEL, order);
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return alloc_bootmem_align(size, size);
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}
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static inline pud_t *vmem_pud_alloc(void)
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{
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pud_t *pud = NULL;
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pud = vmem_alloc_pages(2);
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if (!pud)
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return NULL;
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clear_table((unsigned long *) pud, _REGION3_ENTRY_EMPTY, PAGE_SIZE * 4);
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return pud;
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}
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pmd_t *vmem_pmd_alloc(void)
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{
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pmd_t *pmd = NULL;
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pmd = vmem_alloc_pages(2);
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if (!pmd)
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return NULL;
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clear_table((unsigned long *) pmd, _SEGMENT_ENTRY_EMPTY, PAGE_SIZE * 4);
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return pmd;
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}
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pte_t __ref *vmem_pte_alloc(void)
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{
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pte_t *pte;
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if (slab_is_available())
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pte = (pte_t *) page_table_alloc(&init_mm);
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else
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pte = alloc_bootmem_align(PTRS_PER_PTE * sizeof(pte_t),
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PTRS_PER_PTE * sizeof(pte_t));
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if (!pte)
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return NULL;
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clear_table((unsigned long *) pte, _PAGE_INVALID,
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PTRS_PER_PTE * sizeof(pte_t));
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return pte;
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}
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/*
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* Add a physical memory range to the 1:1 mapping.
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*/
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static int vmem_add_mem(unsigned long start, unsigned long size)
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{
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unsigned long pages4k, pages1m, pages2g;
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unsigned long end = start + size;
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unsigned long address = start;
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pgd_t *pg_dir;
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pud_t *pu_dir;
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pmd_t *pm_dir;
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pte_t *pt_dir;
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int ret = -ENOMEM;
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pages4k = pages1m = pages2g = 0;
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while (address < end) {
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pg_dir = pgd_offset_k(address);
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if (pgd_none(*pg_dir)) {
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pu_dir = vmem_pud_alloc();
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if (!pu_dir)
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goto out;
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pgd_populate(&init_mm, pg_dir, pu_dir);
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}
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pu_dir = pud_offset(pg_dir, address);
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if (MACHINE_HAS_EDAT2 && pud_none(*pu_dir) && address &&
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!(address & ~PUD_MASK) && (address + PUD_SIZE <= end) &&
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!debug_pagealloc_enabled()) {
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pud_val(*pu_dir) = address | pgprot_val(REGION3_KERNEL);
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address += PUD_SIZE;
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pages2g++;
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continue;
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}
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if (pud_none(*pu_dir)) {
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pm_dir = vmem_pmd_alloc();
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if (!pm_dir)
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goto out;
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pud_populate(&init_mm, pu_dir, pm_dir);
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}
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pm_dir = pmd_offset(pu_dir, address);
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if (MACHINE_HAS_EDAT1 && pmd_none(*pm_dir) && address &&
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!(address & ~PMD_MASK) && (address + PMD_SIZE <= end) &&
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!debug_pagealloc_enabled()) {
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pmd_val(*pm_dir) = address | pgprot_val(SEGMENT_KERNEL);
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address += PMD_SIZE;
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pages1m++;
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continue;
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}
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if (pmd_none(*pm_dir)) {
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pt_dir = vmem_pte_alloc();
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if (!pt_dir)
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goto out;
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pmd_populate(&init_mm, pm_dir, pt_dir);
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}
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pt_dir = pte_offset_kernel(pm_dir, address);
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pte_val(*pt_dir) = address | pgprot_val(PAGE_KERNEL);
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address += PAGE_SIZE;
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pages4k++;
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}
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ret = 0;
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out:
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update_page_count(PG_DIRECT_MAP_4K, pages4k);
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update_page_count(PG_DIRECT_MAP_1M, pages1m);
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update_page_count(PG_DIRECT_MAP_2G, pages2g);
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return ret;
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}
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/*
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* Remove a physical memory range from the 1:1 mapping.
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* Currently only invalidates page table entries.
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*/
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static void vmem_remove_range(unsigned long start, unsigned long size)
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{
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unsigned long pages4k, pages1m, pages2g;
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unsigned long end = start + size;
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unsigned long address = start;
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pgd_t *pg_dir;
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pud_t *pu_dir;
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pmd_t *pm_dir;
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pte_t *pt_dir;
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pages4k = pages1m = pages2g = 0;
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while (address < end) {
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pg_dir = pgd_offset_k(address);
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if (pgd_none(*pg_dir)) {
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address += PGDIR_SIZE;
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continue;
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}
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pu_dir = pud_offset(pg_dir, address);
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if (pud_none(*pu_dir)) {
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address += PUD_SIZE;
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continue;
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}
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if (pud_large(*pu_dir)) {
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pud_clear(pu_dir);
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address += PUD_SIZE;
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pages2g++;
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continue;
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}
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pm_dir = pmd_offset(pu_dir, address);
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if (pmd_none(*pm_dir)) {
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address += PMD_SIZE;
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continue;
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}
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if (pmd_large(*pm_dir)) {
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pmd_clear(pm_dir);
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address += PMD_SIZE;
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pages1m++;
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continue;
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}
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pt_dir = pte_offset_kernel(pm_dir, address);
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pte_clear(&init_mm, address, pt_dir);
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address += PAGE_SIZE;
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pages4k++;
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}
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flush_tlb_kernel_range(start, end);
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update_page_count(PG_DIRECT_MAP_4K, -pages4k);
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update_page_count(PG_DIRECT_MAP_1M, -pages1m);
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update_page_count(PG_DIRECT_MAP_2G, -pages2g);
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}
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/*
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* Add a backed mem_map array to the virtual mem_map array.
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*/
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int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
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{
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unsigned long address = start;
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pgd_t *pg_dir;
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pud_t *pu_dir;
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pmd_t *pm_dir;
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pte_t *pt_dir;
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int ret = -ENOMEM;
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for (address = start; address < end;) {
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pg_dir = pgd_offset_k(address);
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if (pgd_none(*pg_dir)) {
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pu_dir = vmem_pud_alloc();
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if (!pu_dir)
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goto out;
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pgd_populate(&init_mm, pg_dir, pu_dir);
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}
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pu_dir = pud_offset(pg_dir, address);
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if (pud_none(*pu_dir)) {
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pm_dir = vmem_pmd_alloc();
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if (!pm_dir)
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goto out;
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pud_populate(&init_mm, pu_dir, pm_dir);
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}
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pm_dir = pmd_offset(pu_dir, address);
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if (pmd_none(*pm_dir)) {
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/* Use 1MB frames for vmemmap if available. We always
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* use large frames even if they are only partially
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* used.
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* Otherwise we would have also page tables since
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* vmemmap_populate gets called for each section
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* separately. */
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if (MACHINE_HAS_EDAT1) {
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void *new_page;
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new_page = vmemmap_alloc_block(PMD_SIZE, node);
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if (!new_page)
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goto out;
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pmd_val(*pm_dir) = __pa(new_page) |
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_SEGMENT_ENTRY | _SEGMENT_ENTRY_LARGE;
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address = (address + PMD_SIZE) & PMD_MASK;
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continue;
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}
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pt_dir = vmem_pte_alloc();
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if (!pt_dir)
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goto out;
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pmd_populate(&init_mm, pm_dir, pt_dir);
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} else if (pmd_large(*pm_dir)) {
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address = (address + PMD_SIZE) & PMD_MASK;
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continue;
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}
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pt_dir = pte_offset_kernel(pm_dir, address);
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if (pte_none(*pt_dir)) {
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void *new_page;
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new_page = vmemmap_alloc_block(PAGE_SIZE, node);
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if (!new_page)
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goto out;
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pte_val(*pt_dir) =
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__pa(new_page) | pgprot_val(PAGE_KERNEL);
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}
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address += PAGE_SIZE;
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}
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ret = 0;
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out:
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return ret;
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}
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void vmemmap_free(unsigned long start, unsigned long end)
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{
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}
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/*
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* Add memory segment to the segment list if it doesn't overlap with
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* an already present segment.
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*/
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static int insert_memory_segment(struct memory_segment *seg)
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{
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struct memory_segment *tmp;
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if (seg->start + seg->size > VMEM_MAX_PHYS ||
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seg->start + seg->size < seg->start)
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return -ERANGE;
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list_for_each_entry(tmp, &mem_segs, list) {
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if (seg->start >= tmp->start + tmp->size)
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continue;
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if (seg->start + seg->size <= tmp->start)
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continue;
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return -ENOSPC;
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}
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list_add(&seg->list, &mem_segs);
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return 0;
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}
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/*
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* Remove memory segment from the segment list.
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*/
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static void remove_memory_segment(struct memory_segment *seg)
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{
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list_del(&seg->list);
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}
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static void __remove_shared_memory(struct memory_segment *seg)
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{
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remove_memory_segment(seg);
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vmem_remove_range(seg->start, seg->size);
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}
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int vmem_remove_mapping(unsigned long start, unsigned long size)
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{
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struct memory_segment *seg;
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int ret;
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mutex_lock(&vmem_mutex);
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ret = -ENOENT;
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list_for_each_entry(seg, &mem_segs, list) {
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if (seg->start == start && seg->size == size)
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break;
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}
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if (seg->start != start || seg->size != size)
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goto out;
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ret = 0;
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__remove_shared_memory(seg);
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kfree(seg);
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out:
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mutex_unlock(&vmem_mutex);
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return ret;
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}
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int vmem_add_mapping(unsigned long start, unsigned long size)
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{
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struct memory_segment *seg;
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int ret;
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mutex_lock(&vmem_mutex);
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ret = -ENOMEM;
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seg = kzalloc(sizeof(*seg), GFP_KERNEL);
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if (!seg)
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goto out;
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seg->start = start;
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seg->size = size;
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ret = insert_memory_segment(seg);
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if (ret)
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goto out_free;
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ret = vmem_add_mem(start, size);
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if (ret)
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goto out_remove;
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goto out;
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out_remove:
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__remove_shared_memory(seg);
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out_free:
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kfree(seg);
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out:
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mutex_unlock(&vmem_mutex);
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return ret;
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}
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/*
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* map whole physical memory to virtual memory (identity mapping)
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* we reserve enough space in the vmalloc area for vmemmap to hotplug
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* additional memory segments.
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*/
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void __init vmem_map_init(void)
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{
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unsigned long size = _eshared - _stext;
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struct memblock_region *reg;
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for_each_memblock(memory, reg)
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vmem_add_mem(reg->base, reg->size);
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set_memory_ro((unsigned long)_stext, size >> PAGE_SHIFT);
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pr_info("Write protected kernel read-only data: %luk\n", size >> 10);
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}
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/*
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* Convert memblock.memory to a memory segment list so there is a single
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* list that contains all memory segments.
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*/
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static int __init vmem_convert_memory_chunk(void)
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{
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struct memblock_region *reg;
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struct memory_segment *seg;
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mutex_lock(&vmem_mutex);
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for_each_memblock(memory, reg) {
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seg = kzalloc(sizeof(*seg), GFP_KERNEL);
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if (!seg)
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panic("Out of memory...\n");
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seg->start = reg->base;
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seg->size = reg->size;
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insert_memory_segment(seg);
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}
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mutex_unlock(&vmem_mutex);
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return 0;
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}
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core_initcall(vmem_convert_memory_chunk);
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