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134 lines
3.2 KiB
134 lines
3.2 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* MMU-generic set_memory implementation for powerpc |
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* |
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* Copyright 2019-2021, IBM Corporation. |
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*/ |
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#include <linux/mm.h> |
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#include <linux/vmalloc.h> |
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#include <linux/set_memory.h> |
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#include <asm/mmu.h> |
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#include <asm/page.h> |
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#include <asm/pgtable.h> |
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/* |
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* Updates the attributes of a page in three steps: |
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* |
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* 1. invalidate the page table entry |
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* 2. flush the TLB |
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* 3. install the new entry with the updated attributes |
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* |
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* Invalidating the pte means there are situations where this will not work |
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* when in theory it should. |
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* For example: |
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* - removing write from page whilst it is being executed |
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* - setting a page read-only whilst it is being read by another CPU |
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* |
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*/ |
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static int change_page_attr(pte_t *ptep, unsigned long addr, void *data) |
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{ |
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long action = (long)data; |
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pte_t pte; |
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spin_lock(&init_mm.page_table_lock); |
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/* invalidate the PTE so it's safe to modify */ |
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pte = ptep_get_and_clear(&init_mm, addr, ptep); |
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flush_tlb_kernel_range(addr, addr + PAGE_SIZE); |
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/* modify the PTE bits as desired, then apply */ |
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switch (action) { |
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case SET_MEMORY_RO: |
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pte = pte_wrprotect(pte); |
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break; |
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case SET_MEMORY_RW: |
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pte = pte_mkwrite(pte_mkdirty(pte)); |
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break; |
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case SET_MEMORY_NX: |
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pte = pte_exprotect(pte); |
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break; |
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case SET_MEMORY_X: |
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pte = pte_mkexec(pte); |
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break; |
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default: |
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WARN_ON_ONCE(1); |
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break; |
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} |
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set_pte_at(&init_mm, addr, ptep, pte); |
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/* See ptesync comment in radix__set_pte_at() */ |
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if (radix_enabled()) |
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asm volatile("ptesync": : :"memory"); |
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spin_unlock(&init_mm.page_table_lock); |
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return 0; |
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} |
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int change_memory_attr(unsigned long addr, int numpages, long action) |
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{ |
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unsigned long start = ALIGN_DOWN(addr, PAGE_SIZE); |
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unsigned long size = numpages * PAGE_SIZE; |
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if (!numpages) |
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return 0; |
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if (WARN_ON_ONCE(is_vmalloc_or_module_addr((void *)addr) && |
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is_vm_area_hugepages((void *)addr))) |
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return -EINVAL; |
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#ifdef CONFIG_PPC_BOOK3S_64 |
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/* |
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* On hash, the linear mapping is not in the Linux page table so |
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* apply_to_existing_page_range() will have no effect. If in the future |
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* the set_memory_* functions are used on the linear map this will need |
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* to be updated. |
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*/ |
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if (!radix_enabled()) { |
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int region = get_region_id(addr); |
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if (WARN_ON_ONCE(region != VMALLOC_REGION_ID && region != IO_REGION_ID)) |
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return -EINVAL; |
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} |
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#endif |
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return apply_to_existing_page_range(&init_mm, start, size, |
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change_page_attr, (void *)action); |
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} |
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/* |
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* Set the attributes of a page: |
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* |
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* This function is used by PPC32 at the end of init to set final kernel memory |
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* protection. It includes changing the maping of the page it is executing from |
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* and data pages it is using. |
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*/ |
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static int set_page_attr(pte_t *ptep, unsigned long addr, void *data) |
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{ |
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pgprot_t prot = __pgprot((unsigned long)data); |
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spin_lock(&init_mm.page_table_lock); |
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set_pte_at(&init_mm, addr, ptep, pte_modify(*ptep, prot)); |
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flush_tlb_kernel_range(addr, addr + PAGE_SIZE); |
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spin_unlock(&init_mm.page_table_lock); |
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return 0; |
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} |
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int set_memory_attr(unsigned long addr, int numpages, pgprot_t prot) |
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{ |
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unsigned long start = ALIGN_DOWN(addr, PAGE_SIZE); |
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unsigned long sz = numpages * PAGE_SIZE; |
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if (numpages <= 0) |
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return 0; |
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return apply_to_existing_page_range(&init_mm, start, sz, set_page_attr, |
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(void *)pgprot_val(prot)); |
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}
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