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![Christophe Leroy](/assets/img/avatar_default.png)
Commit d2f15e0979
("powerpc/32: always populate page tables for
Abatron BDI.") wrongly sets page tables for any PPC32 for using BDI,
and does't update them after init (remove RX on init section, set
text and rodata read-only)
Only the 8xx requires page tables to be populated for using the BDI.
They also need to be populated in order to see the mappings in
/sys/kernel/debug/kernel_page_tables
On BOOK3S_32, pages that are not mapped by page tables are mapped
by BATs. The BDI knows BATs and they can be viewed in
/sys/kernel/debug/powerpc/block_address_translation
Only set pagetables for RAM and IMMR on the 8xx and properly update
them at the end of init.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/c8610942203e0d93fcb02ad20c57edd3adb4c9d3.1566554029.git.christophe.leroy@c-s.fr
252 lines
6 KiB
C
252 lines
6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* This file contains the routines setting up the linux page tables.
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* -- paulus
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*
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* Derived from arch/ppc/mm/init.c:
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* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
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*
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* Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
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* and Cort Dougan (PReP) (cort@cs.nmt.edu)
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* Copyright (C) 1996 Paul Mackerras
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*
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* Derived from "arch/i386/mm/init.c"
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* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/mm.h>
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#include <linux/vmalloc.h>
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#include <linux/init.h>
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#include <linux/highmem.h>
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#include <linux/memblock.h>
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#include <linux/slab.h>
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#include <asm/pgtable.h>
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#include <asm/pgalloc.h>
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#include <asm/fixmap.h>
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#include <asm/setup.h>
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#include <asm/sections.h>
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#include <mm/mmu_decl.h>
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extern char etext[], _stext[], _sinittext[], _einittext[];
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static void __init *early_alloc_pgtable(unsigned long size)
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{
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void *ptr = memblock_alloc(size, size);
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if (!ptr)
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panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
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__func__, size, size);
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return ptr;
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}
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static pte_t __init *early_pte_alloc_kernel(pmd_t *pmdp, unsigned long va)
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{
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if (pmd_none(*pmdp)) {
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pte_t *ptep = early_alloc_pgtable(PTE_FRAG_SIZE);
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pmd_populate_kernel(&init_mm, pmdp, ptep);
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}
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return pte_offset_kernel(pmdp, va);
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}
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int __ref map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot)
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{
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pmd_t *pd;
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pte_t *pg;
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int err = -ENOMEM;
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/* Use upper 10 bits of VA to index the first level map */
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pd = pmd_offset(pud_offset(pgd_offset_k(va), va), va);
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/* Use middle 10 bits of VA to index the second-level map */
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if (likely(slab_is_available()))
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pg = pte_alloc_kernel(pd, va);
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else
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pg = early_pte_alloc_kernel(pd, va);
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if (pg != 0) {
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err = 0;
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/* The PTE should never be already set nor present in the
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* hash table
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*/
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BUG_ON((pte_present(*pg) | pte_hashpte(*pg)) && pgprot_val(prot));
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set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT, prot));
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}
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smp_wmb();
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return err;
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}
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/*
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* Map in a chunk of physical memory starting at start.
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*/
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static void __init __mapin_ram_chunk(unsigned long offset, unsigned long top)
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{
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unsigned long v, s;
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phys_addr_t p;
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int ktext;
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s = offset;
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v = PAGE_OFFSET + s;
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p = memstart_addr + s;
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for (; s < top; s += PAGE_SIZE) {
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ktext = ((char *)v >= _stext && (char *)v < etext) ||
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((char *)v >= _sinittext && (char *)v < _einittext);
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map_kernel_page(v, p, ktext ? PAGE_KERNEL_TEXT : PAGE_KERNEL);
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#ifdef CONFIG_PPC_BOOK3S_32
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if (ktext)
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hash_preload(&init_mm, v);
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#endif
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v += PAGE_SIZE;
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p += PAGE_SIZE;
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}
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}
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void __init mapin_ram(void)
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{
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struct memblock_region *reg;
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for_each_memblock(memory, reg) {
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phys_addr_t base = reg->base;
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phys_addr_t top = min(base + reg->size, total_lowmem);
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if (base >= top)
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continue;
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base = mmu_mapin_ram(base, top);
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__mapin_ram_chunk(base, top);
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}
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}
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/* Scan the real Linux page tables and return a PTE pointer for
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* a virtual address in a context.
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* Returns true (1) if PTE was found, zero otherwise. The pointer to
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* the PTE pointer is unmodified if PTE is not found.
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*/
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static int
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get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep, pmd_t **pmdp)
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{
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pgd_t *pgd;
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pud_t *pud;
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pmd_t *pmd;
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pte_t *pte;
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int retval = 0;
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pgd = pgd_offset(mm, addr & PAGE_MASK);
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if (pgd) {
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pud = pud_offset(pgd, addr & PAGE_MASK);
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if (pud && pud_present(*pud)) {
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pmd = pmd_offset(pud, addr & PAGE_MASK);
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if (pmd_present(*pmd)) {
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pte = pte_offset_map(pmd, addr & PAGE_MASK);
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if (pte) {
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retval = 1;
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*ptep = pte;
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if (pmdp)
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*pmdp = pmd;
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/* XXX caller needs to do pte_unmap, yuck */
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}
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}
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}
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}
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return(retval);
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}
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static int __change_page_attr_noflush(struct page *page, pgprot_t prot)
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{
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pte_t *kpte;
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pmd_t *kpmd;
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unsigned long address;
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BUG_ON(PageHighMem(page));
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address = (unsigned long)page_address(page);
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if (v_block_mapped(address))
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return 0;
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if (!get_pteptr(&init_mm, address, &kpte, &kpmd))
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return -EINVAL;
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__set_pte_at(&init_mm, address, kpte, mk_pte(page, prot), 0);
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pte_unmap(kpte);
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return 0;
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}
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/*
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* Change the page attributes of an page in the linear mapping.
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*
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* THIS DOES NOTHING WITH BAT MAPPINGS, DEBUG USE ONLY
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*/
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static int change_page_attr(struct page *page, int numpages, pgprot_t prot)
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{
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int i, err = 0;
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unsigned long flags;
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struct page *start = page;
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local_irq_save(flags);
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for (i = 0; i < numpages; i++, page++) {
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err = __change_page_attr_noflush(page, prot);
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if (err)
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break;
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}
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wmb();
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local_irq_restore(flags);
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flush_tlb_kernel_range((unsigned long)page_address(start),
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(unsigned long)page_address(page));
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return err;
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}
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void mark_initmem_nx(void)
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{
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struct page *page = virt_to_page(_sinittext);
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unsigned long numpages = PFN_UP((unsigned long)_einittext) -
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PFN_DOWN((unsigned long)_sinittext);
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if (v_block_mapped((unsigned long)_stext + 1))
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mmu_mark_initmem_nx();
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else
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change_page_attr(page, numpages, PAGE_KERNEL);
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}
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#ifdef CONFIG_STRICT_KERNEL_RWX
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void mark_rodata_ro(void)
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{
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struct page *page;
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unsigned long numpages;
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if (v_block_mapped((unsigned long)_sinittext)) {
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mmu_mark_rodata_ro();
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return;
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}
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page = virt_to_page(_stext);
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numpages = PFN_UP((unsigned long)_etext) -
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PFN_DOWN((unsigned long)_stext);
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change_page_attr(page, numpages, PAGE_KERNEL_ROX);
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/*
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* mark .rodata as read only. Use __init_begin rather than __end_rodata
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* to cover NOTES and EXCEPTION_TABLE.
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*/
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page = virt_to_page(__start_rodata);
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numpages = PFN_UP((unsigned long)__init_begin) -
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PFN_DOWN((unsigned long)__start_rodata);
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change_page_attr(page, numpages, PAGE_KERNEL_RO);
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// mark_initmem_nx() should have already run by now
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ptdump_check_wx();
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}
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#endif
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#ifdef CONFIG_DEBUG_PAGEALLOC
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void __kernel_map_pages(struct page *page, int numpages, int enable)
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{
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if (PageHighMem(page))
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return;
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change_page_attr(page, numpages, enable ? PAGE_KERNEL : __pgprot(0));
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}
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#endif /* CONFIG_DEBUG_PAGEALLOC */
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