xref: /kernel/linux/linux-5.10/arch/arm64/include/asm/mman.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_MMAN_H__
#define __ASM_MMAN_H__

#include <linux/compiler.h>
#include <linux/types.h>
#include <uapi/asm/mman.h>

static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot,
	unsigned long pkey __always_unused)
{
	unsigned long ret = 0;

	if (system_supports_bti() && (prot & PROT_BTI))
		ret |= VM_ARM64_BTI;

	if (system_supports_mte() && (prot & PROT_MTE))
		ret |= VM_MTE;

	return ret;
}
#define arch_calc_vm_prot_bits(prot, pkey) arch_calc_vm_prot_bits(prot, pkey)

static inline unsigned long arch_calc_vm_flag_bits(unsigned long flags)
{
	/*
	 * Only allow MTE on anonymous mappings as these are guaranteed to be
	 * backed by tags-capable memory. The vm_flags may be overridden by a
	 * filesystem supporting MTE (RAM-based).
	 */
	if (system_supports_mte() && (flags & MAP_ANONYMOUS))
		return VM_MTE_ALLOWED;

	return 0;
}
#define arch_calc_vm_flag_bits(flags) arch_calc_vm_flag_bits(flags)

static inline pgprot_t arch_vm_get_page_prot(unsigned long vm_flags)
{
	pteval_t prot = 0;

	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);

	return __pgprot(prot);
}
#define arch_vm_get_page_prot(vm_flags) arch_vm_get_page_prot(vm_flags)

static inline bool arch_validate_prot(unsigned long prot,
	unsigned long addr __always_unused)
{
	unsigned long supported = PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM;

	if (system_supports_bti())
		supported |= PROT_BTI;

	if (system_supports_mte())
		supported |= PROT_MTE;

	return (prot & ~supported) == 0;
}
#define arch_validate_prot(prot, addr) arch_validate_prot(prot, addr)

static inline bool arch_validate_flags(unsigned long vm_flags)
{
	if (!system_supports_mte())
		return true;

	/* only allow VM_MTE if VM_MTE_ALLOWED has been set previously */
	return !(vm_flags & VM_MTE) || (vm_flags & VM_MTE_ALLOWED);
}
#define arch_validate_flags(vm_flags) arch_validate_flags(vm_flags)

#endif /* ! __ASM_MMAN_H__ */