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// SPDX-License-Identifier: GPL-2.0-only
/*
* Based on arch/arm/mm/mmap.c
*
* Copyright (C) 2012 ARM Ltd.
*/
#include <linux/io.h>
#include <linux/memblock.h>
#include <linux/mm.h>
#include <linux/types.h>
#include <asm/cpufeature.h>
#include <asm/page.h>
static pgprot_t protection_map[16] __ro_after_init = {
[VM_NONE] = PAGE_NONE,
[VM_READ] = PAGE_READONLY,
[VM_WRITE] = PAGE_READONLY,
[VM_WRITE | VM_READ] = PAGE_READONLY,
/* PAGE_EXECONLY if Enhanced PAN */
[VM_EXEC] = PAGE_READONLY_EXEC,
[VM_EXEC | VM_READ] = PAGE_READONLY_EXEC,
[VM_EXEC | VM_WRITE] = PAGE_READONLY_EXEC,
[VM_EXEC | VM_WRITE | VM_READ] = PAGE_READONLY_EXEC,
[VM_SHARED] = PAGE_NONE,
[VM_SHARED | VM_READ] = PAGE_READONLY,
[VM_SHARED | VM_WRITE] = PAGE_SHARED,
[VM_SHARED | VM_WRITE | VM_READ] = PAGE_SHARED,
/* PAGE_EXECONLY if Enhanced PAN */
[VM_SHARED | VM_EXEC] = PAGE_READONLY_EXEC,
[VM_SHARED | VM_EXEC | VM_READ] = PAGE_READONLY_EXEC,
[VM_SHARED | VM_EXEC | VM_WRITE] = PAGE_SHARED_EXEC,
[VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = PAGE_SHARED_EXEC
};
static ptdesc_t gcs_page_prot __ro_after_init = _PAGE_GCS_RO;
/*
* You really shouldn't be using read() or write() on /dev/mem. This might go
* away in the future.
*/
int valid_phys_addr_range(phys_addr_t addr, size_t size)
{
/*
* Check whether addr is covered by a memory region without the
* MEMBLOCK_NOMAP attribute, and whether that region covers the
* entire range. In theory, this could lead to false negatives
* if the range is covered by distinct but adjacent memory regions
* that only differ in other attributes. However, few of such
* attributes have been defined, and it is debatable whether it
* follows that /dev/mem read() calls should be able traverse
* such boundaries.
*/
return memblock_is_region_memory(addr, size) &&
memblock_is_map_memory(addr);
}
/*
* Do not allow /dev/mem mappings beyond the supported physical range.
*/
int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
{
return !(((pfn << PAGE_SHIFT) + size) & ~PHYS_MASK);
}
static int __init adjust_protection_map(void)
{
/*
* With Enhanced PAN we can honour the execute-only permissions as
* there is no PAN override with such mappings.
*/
if (cpus_have_cap(ARM64_HAS_EPAN)) {
protection_map[VM_EXEC] = PAGE_EXECONLY;
protection_map[VM_EXEC | VM_SHARED] = PAGE_EXECONLY;
}
if (lpa2_is_enabled()) {
for (int i = 0; i < ARRAY_SIZE(protection_map); i++)
pgprot_val(protection_map[i]) &= ~PTE_SHARED;
gcs_page_prot &= ~PTE_SHARED;
}
return 0;
}
arch_initcall(adjust_protection_map);
pgprot_t vm_get_page_prot(vm_flags_t vm_flags)
{
ptdesc_t prot;
/* Short circuit GCS to avoid bloating the table. */
if (system_supports_gcs() && (vm_flags & VM_SHADOW_STACK)) {
/* Honour mprotect(PROT_NONE) on shadow stack mappings */
if (vm_flags & VM_ACCESS_FLAGS)
prot = gcs_page_prot;
else
prot = pgprot_val(protection_map[VM_NONE]);
} else {
prot = pgprot_val(protection_map[vm_flags &
(VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]);
}
if (vm_flags & VM_ARM64_BTI)
prot |= PTE_GP;
/*
* There are two conditions required for returning a Normal Tagged
* memory type: (1) the user requested it via PROT_MTE passed to
* mmap() or mprotect() and (2) the corresponding vma supports MTE. We
* register (1) as VM_MTE in the vma->vm_flags and (2) as
* VM_MTE_ALLOWED. Note that the latter can only be set during the
* mmap() call since mprotect() does not accept MAP_* flags.
* Checking for VM_MTE only is sufficient since arch_validate_flags()
* does not permit (VM_MTE & !VM_MTE_ALLOWED).
*/
if (vm_flags & VM_MTE)
prot |= PTE_ATTRINDX(MT_NORMAL_TAGGED);
#ifdef CONFIG_ARCH_HAS_PKEYS
if (system_supports_poe()) {
if (vm_flags & VM_PKEY_BIT0)
prot |= PTE_PO_IDX_0;
if (vm_flags & VM_PKEY_BIT1)
prot |= PTE_PO_IDX_1;
if (vm_flags & VM_PKEY_BIT2)
prot |= PTE_PO_IDX_2;
}
#endif
return __pgprot(prot);
}
EXPORT_SYMBOL(vm_get_page_prot);
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