1 files changed, 55 insertions, 13 deletions

diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index 712718aed5dd..a81cb4aa4738 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -10,11 +10,13 @@
 #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)
 {
@@ -29,13 +31,21 @@ static bool region_is_misaligned(const efi_memory_desc_t *md)
  * executable, everything else can be mapped with the XN bits
  * set. Also take the new (optional) RO/XP bits into account.
  */
-static __init pteval_t create_mapping_protection(efi_memory_desc_t *md)
+static __init ptdesc_t create_mapping_protection(efi_memory_desc_t *md)
 {
 	u64 attr = md->attribute;
 	u32 type = md->type;
 
-	if (type == EFI_MEMORY_MAPPED_IO)
-		return PROT_DEVICE_nGnRE;
+	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;
@@ -75,7 +85,7 @@ static __init pteval_t create_mapping_protection(efi_memory_desc_t *md)
 
 int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md)
 {
-	pteval_t prot_val = create_mapping_protection(md);
+	ptdesc_t prot_val = create_mapping_protection(md);
 	bool page_mappings_only = (md->type == EFI_RUNTIME_SERVICES_CODE ||
 				   md->type == EFI_RUNTIME_SERVICES_DATA);
 
@@ -156,20 +166,53 @@ asmlinkage efi_status_t efi_handle_corrupted_x18(efi_status_t s, const char *f)
 	return s;
 }
 
-static DEFINE_RAW_SPINLOCK(efi_rt_lock);
-
 void arch_efi_call_virt_setup(void)
 {
-	efi_virtmap_load();
+	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();
+	}
+
+	/*
+	 * 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();
+
 	__efi_fpsimd_begin();
-	raw_spin_lock(&efi_rt_lock);
 }
 
 void arch_efi_call_virt_teardown(void)
 {
-	raw_spin_unlock(&efi_rt_lock);
 	__efi_fpsimd_end();
-	efi_virtmap_unload();
+
+	/*
+	 * 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;
@@ -206,9 +249,8 @@ static int __init arm64_efi_rt_init(void)
 	if (!efi_enabled(EFI_RUNTIME_SERVICES))
 		return 0;
 
-	p = __vmalloc_node(THREAD_SIZE, THREAD_ALIGN, GFP_KERNEL,
-			   NUMA_NO_NODE, &&l);
-l:	if (!p) {
+	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;