// SPDX-License-Identifier: GPL-2.0-only/* * Extensible Firmware Interface * * Based on Extensible Firmware Interface Specification version 2.4 * * Copyright (C) 2013, 2014 Linaro Ltd. */ #include <linux/efi.h>#include <linux/init.h>#include <linux/kmemleak.h>#include <linux/kthread.h>#include <linux/screen_info.h>#include <linux/vmalloc.h> #include <asm/efi.h>#include <asm/stacktrace.h>#include <asm/vmap_stack.h> static bool region_is_misaligned(const efi_memory_desc_t *md){	if (PAGE_SIZE == EFI_PAGE_SIZE)		return false;	return !PAGE_ALIGNED(md->phys_addr) ||	       !PAGE_ALIGNED(md->num_pages << EFI_PAGE_SHIFT);} /* * Only regions of type EFI_RUNTIME_SERVICES_CODE need to be * executable, everything else can be mapped with the XN bits * set. Also take the new (optional) RO/XP bits into account. */static __init ptval_t create_mapping_protection(efi_memory_desc_t *md){	u64 attr = md->attribute;	u32 type = md->type; 	if (type == EFI_MEMORY_MAPPED_IO) {		pgprot_t prot = __pgprot(PROT_DEVICE_nGnRE); 		if (arm64_is_protected_mmio(md->phys_addr,					    md->num_pages << EFI_PAGE_SHIFT))			prot = pgprot_encrypted(prot);		else			prot = pgprot_decrypted(prot);		return pgprot_val(prot);	} 	if (region_is_misaligned(md)) {		static bool __initdata code_is_misaligned; 		/*		 * Regions that are not aligned to the OS page size cannot be		 * mapped with strict permissions, as those might interfere		 * with the permissions that are needed by the adjacent		 * region's mapping. However, if we haven't encountered any		 * misaligned runtime code regions so far, we can safely use		 * non-executable permissions for non-code regions.		 */		code_is_misaligned |= (type == EFI_RUNTIME_SERVICES_CODE); 		return code_is_misaligned ? pgprot_val(PAGE_KERNEL_EXEC)					  : pgprot_val(PAGE_KERNEL);	} 	/* R-- */	if ((attr & (EFI_MEMORY_XP | EFI_MEMORY_RO)) ==	    (EFI_MEMORY_XP | EFI_MEMORY_RO))		return pgprot_val(PAGE_KERNEL_RO); 	/* R-X */	if (attr & EFI_MEMORY_RO)		return pgprot_val(PAGE_KERNEL_ROX); 	/* RW- */	if (((attr & (EFI_MEMORY_RP | EFI_MEMORY_WP | EFI_MEMORY_XP)) ==	     EFI_MEMORY_XP) ||	    type != EFI_RUNTIME_SERVICES_CODE)		return pgprot_val(PAGE_KERNEL); 	/* RWX */	return pgprot_val(PAGE_KERNEL_EXEC);} int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md){	ptval_t prot_val = create_mapping_protection(md);	bool page_mappings_only = (md->type == EFI_RUNTIME_SERVICES_CODE ||				   md->type == EFI_RUNTIME_SERVICES_DATA); 	/*	 * If this region is not aligned to the page size used by the OS, the	 * mapping will be rounded outwards, and may end up sharing a page	 * frame with an adjacent runtime memory region. Given that the page	 * table descriptor covering the shared page will be rewritten when the	 * adjacent region gets mapped, we must avoid block mappings here so we	 * don't have to worry about splitting them when that happens.	 */	if (region_is_misaligned(md))		page_mappings_only = true; 	create_pgd_mapping(mm, md->phys_addr, md->virt_addr,			   md->num_pages << EFI_PAGE_SHIFT,			   __pgprot(prot_val | PTE_NG), page_mappings_only);	return 0;} struct set_perm_data {	const efi_memory_desc_t	*md;	bool			has_bti;}; static int __init set_permissions(pte_t *ptep, unsigned long addr, void *data){	struct set_perm_data *spd = data;	const efi_memory_desc_t *md = spd->md;	pte_t pte = __ptep_get(ptep); 	if (md->attribute & EFI_MEMORY_RO)		pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));	if (md->attribute & EFI_MEMORY_XP)		pte = set_pte_bit(pte, __pgprot(PTE_PXN));	else if (system_supports_bti_kernel() && spd->has_bti)		pte = set_pte_bit(pte, __pgprot(PTE_GP));	__set_pte(ptep, pte);	return 0;} int __init efi_set_mapping_permissions(struct mm_struct *mm,				       efi_memory_desc_t *md,				       bool has_bti){	struct set_perm_data data = { md, has_bti }; 	BUG_ON(md->type != EFI_RUNTIME_SERVICES_CODE &&	       md->type != EFI_RUNTIME_SERVICES_DATA); 	if (region_is_misaligned(md))		return 0; 	/*	 * Calling apply_to_page_range() is only safe on regions that are	 * guaranteed to be mapped down to pages. Since we are only called	 * for regions that have been mapped using efi_create_mapping() above	 * (and this is checked by the generic Memory Attributes table parsing	 * routines), there is no need to check that again here.	 */	return apply_to_page_range(mm, md->virt_addr,				   md->num_pages << EFI_PAGE_SHIFT,				   set_permissions, &data);} /* * UpdateCapsule() depends on the system being shutdown via * ResetSystem(). */bool efi_poweroff_required(void){	return efi_enabled(EFI_RUNTIME_SERVICES);} asmlinkage efi_status_t efi_handle_corrupted_x18(efi_status_t s, const char *f){	pr_err_ratelimited(FW_BUG "register x18 corrupted by EFI %s\n", f);	return s;} void arch_efi_call_virt_setup(void){	efi_runtime_assert_lock_held(); 	if (preemptible() && (current->flags & PF_KTHREAD)) {		/*		 * Disable migration to ensure that a preempted EFI runtime		 * service call will be resumed on the same CPU. This avoids		 * potential issues with EFI runtime calls that are preempted		 * while polling for an asynchronous completion of a secure		 * firmware call, which may not permit the CPU to change.		 */		migrate_disable();		kthread_use_mm(&efi_mm);	} else {		efi_virtmap_load();	} 	__efi_fpsimd_begin(); 	/*	 * Enable access to the valid TTBR0_EL1 and invoke the errata	 * workaround directly since there is no return from exception when	 * invoking the EFI run-time services.	 */	uaccess_ttbr0_enable();	post_ttbr_update_workaround();} void arch_efi_call_virt_teardown(void){	__efi_fpsimd_end(); 	/*	 * Defer the switch to the current thread's TTBR0_EL1 until	 * uaccess_enable(). Do so before efi_virtmap_unload() updates the	 * saved TTBR0 value, so the userland page tables are not activated	 * inadvertently over the back of an exception.	 */	uaccess_ttbr0_disable(); 	if (preemptible() && (current->flags & PF_KTHREAD)) {		kthread_unuse_mm(&efi_mm);		migrate_enable();	} else {		efi_virtmap_unload();	}} asmlinkage u64 *efi_rt_stack_top __ro_after_init; asmlinkage efi_status_t __efi_rt_asm_recover(void); bool efi_runtime_fixup_exception(struct pt_regs *regs, const char *msg){	 /* Check whether the exception occurred while running the firmware */	if (!current_in_efi() || regs->pc >= TASK_SIZE_64)		return false; 	pr_err(FW_BUG "Unable to handle %s in EFI runtime service\n", msg);	add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);	clear_bit(EFI_RUNTIME_SERVICES, &efi.flags); 	regs->regs[0]	= EFI_ABORTED;	regs->regs[30]	= efi_rt_stack_top[-1];	regs->pc	= (u64)__efi_rt_asm_recover; 	if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK))		regs->regs[18] = efi_rt_stack_top[-2]; 	return true;} /* EFI requires 8 KiB of stack space for runtime services */static_assert(THREAD_SIZE >= SZ_8K); static int __init arm64_efi_rt_init(void){	void *p; 	if (!efi_enabled(EFI_RUNTIME_SERVICES))		return 0; 	p = arch_alloc_vmap_stack(THREAD_SIZE, NUMA_NO_NODE);	if (!p) {		pr_warn("Failed to allocate EFI runtime stack\n");		clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);		return -ENOMEM;	} 	kmemleak_not_leak(p);	efi_rt_stack_top = p + THREAD_SIZE;	return 0;}core_initcall(arm64_efi_rt_init);