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To enable tagging on a memory range, the user must explicitly opt in via a new PROT_MTE flag passed to mmap() or mprotect(). Since this is a new memory type in the AttrIndx field of a pte, simplify the or'ing of these bits over the protection_map[] attributes by making MT_NORMAL index 0. There are two conditions for arch_vm_get_page_prot() to return the MT_NORMAL_TAGGED memory type: (1) the user requested it via PROT_MTE, registered as VM_MTE in the vm_flags, and (2) the vma supports MTE, decided during the mmap() call (only) and registered as VM_MTE_ALLOWED. arch_calc_vm_prot_bits() is responsible for registering the user request as VM_MTE. The newly introduced arch_calc_vm_flag_bits() sets VM_MTE_ALLOWED if the mapping is MAP_ANONYMOUS. An MTE-capable filesystem (RAM-based) may be able to set VM_MTE_ALLOWED during its mmap() file ops call. In addition, update VM_DATA_DEFAULT_FLAGS to allow mprotect(PROT_MTE) on stack or brk area. The Linux mmap() syscall currently ignores unknown PROT_* flags. In the presence of MTE, an mmap(PROT_MTE) on a file which does not support MTE will not report an error and the memory will not be mapped as Normal Tagged. For consistency, mprotect(PROT_MTE) will not report an error either if the memory range does not support MTE. Two subsequent patches in the series will propose tightening of this behaviour. Co-developed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org>
51 lines
1.2 KiB
C
51 lines
1.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Based on arch/arm/include/asm/page.h
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*
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* Copyright (C) 1995-2003 Russell King
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* Copyright (C) 2012 ARM Ltd.
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*/
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#ifndef __ASM_PAGE_H
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#define __ASM_PAGE_H
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#include <asm/page-def.h>
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#ifndef __ASSEMBLY__
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#include <linux/personality.h> /* for READ_IMPLIES_EXEC */
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#include <asm/pgtable-types.h>
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struct page;
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struct vm_area_struct;
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extern void copy_page(void *to, const void *from);
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extern void clear_page(void *to);
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void copy_user_highpage(struct page *to, struct page *from,
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unsigned long vaddr, struct vm_area_struct *vma);
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#define __HAVE_ARCH_COPY_USER_HIGHPAGE
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void copy_highpage(struct page *to, struct page *from);
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#define __HAVE_ARCH_COPY_HIGHPAGE
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#define __alloc_zeroed_user_highpage(movableflags, vma, vaddr) \
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alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, vaddr)
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#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
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#define clear_user_page(page, vaddr, pg) clear_page(page)
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#define copy_user_page(to, from, vaddr, pg) copy_page(to, from)
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typedef struct page *pgtable_t;
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extern int pfn_valid(unsigned long);
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#include <asm/memory.h>
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#endif /* !__ASSEMBLY__ */
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#define VM_DATA_DEFAULT_FLAGS (VM_DATA_FLAGS_TSK_EXEC | VM_MTE_ALLOWED)
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#include <asm-generic/getorder.h>
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#endif
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