3 files changed, 17 insertions, 1 deletions
diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
index 31d13a6001df..de4ff90785b2 100644
--- a/arch/arm64/include/asm/efi.h
+++ b/arch/arm64/include/asm/efi.h
@@ -48,8 +48,17 @@ int efi_set_mapping_permissions(struct mm_struct *mm, efi_memory_desc_t *md);
 })
 
 extern spinlock_t efi_rt_lock;
+extern u64 *efi_rt_stack_top;
 efi_status_t __efi_rt_asm_wrapper(void *, const char *, ...);
 
+/*
+ * efi_rt_stack_top[-1] contains the value the stack pointer had before
+ * switching to the EFI runtime stack.
+ */
+#define current_in_efi()						\
+	(!preemptible() && efi_rt_stack_top != NULL &&			\
+	 on_task_stack(current, READ_ONCE(efi_rt_stack_top[-1]), 1))
+
 #define ARCH_EFI_IRQ_FLAGS_MASK (PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT)
 
 /*
diff --git a/arch/arm64/kernel/efi-rt-wrapper.S b/arch/arm64/kernel/efi-rt-wrapper.S
index d872d18101d8..e8ae803662cf 100644
--- a/arch/arm64/kernel/efi-rt-wrapper.S
+++ b/arch/arm64/kernel/efi-rt-wrapper.S
@@ -46,7 +46,10 @@ SYM_FUNC_START(__efi_rt_asm_wrapper)
 	mov	x4, x6
 	blr	x8
 
+	mov	x16, sp
 	mov	sp, x29
+	str	xzr, [x16, #8]			// clear recorded task SP value
+
 	ldp	x1, x2, [sp, #16]
 	cmp	x2, x18
 	ldp	x29, x30, [sp], #112
@@ -71,6 +74,9 @@ SYM_FUNC_END(__efi_rt_asm_wrapper)
 SYM_CODE_START(__efi_rt_asm_recover)
 	mov	sp, x30
 
+	ldr_l	x16, efi_rt_stack_top		// clear recorded task SP value
+	str	xzr, [x16, #-8]
+
 	ldp	x19, x20, [sp, #32]
 	ldp	x21, x22, [sp, #48]
 	ldp	x23, x24, [sp, #64]
diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index fab05de2e12d..b273900f4566 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -11,6 +11,7 @@
 #include <linux/init.h>
 
 #include <asm/efi.h>
+#include <asm/stacktrace.h>
 
 static bool region_is_misaligned(const efi_memory_desc_t *md)
 {
@@ -154,7 +155,7 @@ 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_work() != &efi_rts_work.work || regs->pc >= TASK_SIZE_64)
+	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);