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set_memory_attr() was implemented by commit4d1755b6a7("powerpc/mm: implement set_memory_attr()") because the set_memory_xx() couldn't be used at that time to modify memory "on the fly" as explained it the commit. But set_memory_attr() uses set_pte_at() which leads to warnings when CONFIG_DEBUG_VM is selected, because set_pte_at() is unexpected for updating existing page table entries. The check could be bypassed by using __set_pte_at() instead, as it was the case before commitc988cfd38e("powerpc/32: use set_memory_attr()") but since commit9f7853d760("powerpc/mm: Fix set_memory_*() against concurrent accesses") it is now possible to use set_memory_xx() functions to update page table entries "on the fly" because the update is now atomic. For DEBUG_PAGEALLOC we need to clear and set back _PAGE_PRESENT. Add set_memory_np() and set_memory_p() for that. Replace all uses of set_memory_attr() by the relevant set_memory_xx() and remove set_memory_attr(). Fixes:c988cfd38e("powerpc/32: use set_memory_attr()") Cc: stable@vger.kernel.org Reported-by: Maxime Bizon <mbizon@freebox.fr> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Tested-by: Maxime Bizon <mbizon@freebox.fr> Reviewed-by: Russell Currey <ruscur@russell.cc> Depends-on:9f7853d760("powerpc/mm: Fix set_memory_*() against concurrent accesses") Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/cda2b44b55c96f9ac69fa92e68c01084ec9495c5.1640344012.git.christophe.leroy@csgroup.eu
99 lines
2.5 KiB
C
99 lines
2.5 KiB
C
// 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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static pte_basic_t pte_update_delta(pte_t *ptep, unsigned long addr,
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unsigned long old, unsigned long new)
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{
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return pte_update(&init_mm, addr, ptep, old & ~new, new & ~old, 0);
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}
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/*
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* Updates the attributes of a page atomically.
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*
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* This sequence is safe against concurrent updates, and also allows updating the
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* attributes of a page currently being executed or accessed.
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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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/* modify the PTE bits as desired */
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switch (action) {
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case SET_MEMORY_RO:
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/* Don't clear DIRTY bit */
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pte_update_delta(ptep, addr, _PAGE_KERNEL_RW & ~_PAGE_DIRTY, _PAGE_KERNEL_RO);
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break;
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case SET_MEMORY_RW:
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pte_update_delta(ptep, addr, _PAGE_KERNEL_RO, _PAGE_KERNEL_RW);
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break;
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case SET_MEMORY_NX:
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pte_update_delta(ptep, addr, _PAGE_KERNEL_ROX, _PAGE_KERNEL_RO);
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break;
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case SET_MEMORY_X:
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pte_update_delta(ptep, addr, _PAGE_KERNEL_RO, _PAGE_KERNEL_ROX);
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break;
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case SET_MEMORY_NP:
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pte_update(&init_mm, addr, ptep, _PAGE_PRESENT, 0, 0);
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break;
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case SET_MEMORY_P:
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pte_update(&init_mm, addr, ptep, 0, _PAGE_PRESENT, 0);
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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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/* 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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flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
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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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