diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h
index 8719ce122a38e3083c41305519f1ca369fd36215..4128bec033f65dcb466d5d2f7799799ab51dca6e 100644
--- a/arch/arm64/include/asm/asm-uaccess.h
+++ b/arch/arm64/include/asm/asm-uaccess.h
@@ -14,11 +14,11 @@
 #ifdef CONFIG_ARM64_SW_TTBR0_PAN
 	.macro	__uaccess_ttbr0_disable, tmp1
 	mrs	\tmp1, ttbr1_el1			// swapper_pg_dir
+	bic	\tmp1, \tmp1, #TTBR_ASID_MASK
 	sub	\tmp1, \tmp1, #RESERVED_TTBR0_SIZE	// reserved_ttbr0 just before swapper_pg_dir
 	msr	ttbr0_el1, \tmp1			// set reserved TTBR0_EL1
 	isb
 	add	\tmp1, \tmp1, #RESERVED_TTBR0_SIZE
-	bic	\tmp1, \tmp1, #TTBR_ASID_MASK
 	msr	ttbr1_el1, \tmp1		// set reserved ASID
 	isb
 	.endm
@@ -35,9 +35,11 @@
 	isb
 	.endm
 
-	.macro	uaccess_ttbr0_disable, tmp1
+	.macro	uaccess_ttbr0_disable, tmp1, tmp2
 alternative_if_not ARM64_HAS_PAN
+	save_and_disable_irq \tmp2		// avoid preemption
 	__uaccess_ttbr0_disable \tmp1
+	restore_irq \tmp2
 alternative_else_nop_endif
 	.endm
 
@@ -49,7 +51,7 @@ alternative_if_not ARM64_HAS_PAN
 alternative_else_nop_endif
 	.endm
 #else
-	.macro	uaccess_ttbr0_disable, tmp1
+	.macro	uaccess_ttbr0_disable, tmp1, tmp2
 	.endm
 
 	.macro	uaccess_ttbr0_enable, tmp1, tmp2, tmp3
@@ -59,8 +61,8 @@ alternative_else_nop_endif
 /*
  * These macros are no-ops when UAO is present.
  */
-	.macro	uaccess_disable_not_uao, tmp1
-	uaccess_ttbr0_disable \tmp1
+	.macro	uaccess_disable_not_uao, tmp1, tmp2
+	uaccess_ttbr0_disable \tmp1, \tmp2
 alternative_if ARM64_ALT_PAN_NOT_UAO
 	SET_PSTATE_PAN(1)
 alternative_else_nop_endif
diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
index c4cd5081d78bc4b66e34f3c283d9b1f6ba48518c..8389050328bba2c272b2fe7c6818083ff206d908 100644
--- a/arch/arm64/include/asm/efi.h
+++ b/arch/arm64/include/asm/efi.h
@@ -121,19 +121,21 @@ static inline void efi_set_pgd(struct mm_struct *mm)
 		if (mm != current->active_mm) {
 			/*
 			 * Update the current thread's saved ttbr0 since it is
-			 * restored as part of a return from exception. Set
-			 * the hardware TTBR0_EL1 using cpu_switch_mm()
-			 * directly to enable potential errata workarounds.
+			 * restored as part of a return from exception. 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.
 			 */
 			update_saved_ttbr0(current, mm);
-			cpu_switch_mm(mm->pgd, mm);
+			uaccess_ttbr0_enable();
+			post_ttbr_update_workaround();
 		} else {
 			/*
 			 * Defer the switch to the current thread's TTBR0_EL1
 			 * until uaccess_enable(). Restore the current
 			 * thread's saved ttbr0 corresponding to its active_mm
 			 */
-			cpu_set_reserved_ttbr0();
+			uaccess_ttbr0_disable();
 			update_saved_ttbr0(current, current->active_mm);
 		}
 	}
diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index 5aee199055563fb2f3eacb7fe6ec82877ea9b129..8d3331985d2e34b2099eab6cec8b456d40983052 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -184,7 +184,7 @@ static inline void update_saved_ttbr0(struct task_struct *tsk,
 	else
 		ttbr = virt_to_phys(mm->pgd) | ASID(mm) << 48;
 
-	task_thread_info(tsk)->ttbr0 = ttbr;
+	WRITE_ONCE(task_thread_info(tsk)->ttbr0, ttbr);
 }
 #else
 static inline void update_saved_ttbr0(struct task_struct *tsk,
@@ -239,6 +239,7 @@ switch_mm(struct mm_struct *prev, struct mm_struct *next,
 #define activate_mm(prev,next)	switch_mm(prev, next, current)
 
 void verify_cpu_asid_bits(void);
+void post_ttbr_update_workaround(void);
 
 #endif /* !__ASSEMBLY__ */
 
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 01ade20d5456810656dcc72fb535d7dad033d140..59fda529293669149097075542f8ff972d491738 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -105,16 +105,18 @@ static inline void set_fs(mm_segment_t fs)
 #ifdef CONFIG_ARM64_SW_TTBR0_PAN
 static inline void __uaccess_ttbr0_disable(void)
 {
-	unsigned long ttbr;
+	unsigned long flags, ttbr;
 
+	local_irq_save(flags);
 	ttbr = read_sysreg(ttbr1_el1);
+	ttbr &= ~TTBR_ASID_MASK;
 	/* reserved_ttbr0 placed before swapper_pg_dir */
 	write_sysreg(ttbr - RESERVED_TTBR0_SIZE, ttbr0_el1);
 	isb();
 	/* Set reserved ASID */
-	ttbr &= ~TTBR_ASID_MASK;
 	write_sysreg(ttbr, ttbr1_el1);
 	isb();
+	local_irq_restore(flags);
 }
 
 static inline void __uaccess_ttbr0_enable(void)
@@ -127,10 +129,11 @@ static inline void __uaccess_ttbr0_enable(void)
 	 * roll-over and an update of 'ttbr0'.
 	 */
 	local_irq_save(flags);
-	ttbr0 = current_thread_info()->ttbr0;
+	ttbr0 = READ_ONCE(current_thread_info()->ttbr0);
 
 	/* Restore active ASID */
 	ttbr1 = read_sysreg(ttbr1_el1);
+	ttbr1 &= ~TTBR_ASID_MASK;		/* safety measure */
 	ttbr1 |= ttbr0 & TTBR_ASID_MASK;
 	write_sysreg(ttbr1, ttbr1_el1);
 	isb();
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 1e1d1842888da3aff574b45f5af364fc1e3d168f..b34e717d75970cba4f646d204265d5c0d84e89c0 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -204,7 +204,7 @@ alternative_if ARM64_HAS_PAN
 alternative_else_nop_endif
 
 	.if	\el != 0
-	mrs	x21, ttbr1_el1
+	mrs	x21, ttbr0_el1
 	tst	x21, #TTBR_ASID_MASK		// Check for the reserved ASID
 	orr	x23, x23, #PSR_PAN_BIT		// Set the emulated PAN in the saved SPSR
 	b.eq	1f				// TTBR0 access already disabled
diff --git a/arch/arm64/lib/clear_user.S b/arch/arm64/lib/clear_user.S
index 8f9c4641e706b26e2956d50556a51d15716f007c..3d69a8d41fa5e59217d5a451cf2ed67bb460a483 100644
--- a/arch/arm64/lib/clear_user.S
+++ b/arch/arm64/lib/clear_user.S
@@ -50,7 +50,7 @@ uao_user_alternative 9f, strh, sttrh, wzr, x0, 2
 	b.mi	5f
 uao_user_alternative 9f, strb, sttrb, wzr, x0, 0
 5:	mov	x0, #0
-	uaccess_disable_not_uao x2
+	uaccess_disable_not_uao x2, x3
 	ret
 ENDPROC(__clear_user)
 
diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S
index 69d86a80f3e2a3e3cae9c90afdfd7aee013e4924..20305d485046754c7c59c48ef28c77dfc54f2ca0 100644
--- a/arch/arm64/lib/copy_from_user.S
+++ b/arch/arm64/lib/copy_from_user.S
@@ -67,7 +67,7 @@ ENTRY(__arch_copy_from_user)
 	uaccess_enable_not_uao x3, x4, x5
 	add	end, x0, x2
 #include "copy_template.S"
-	uaccess_disable_not_uao x3
+	uaccess_disable_not_uao x3, x4
 	mov	x0, #0				// Nothing to copy
 	ret
 ENDPROC(__arch_copy_from_user)
diff --git a/arch/arm64/lib/copy_in_user.S b/arch/arm64/lib/copy_in_user.S
index e442b531252ad87704e9a4f829be4902637922cb..fbb090f431a5c0790c9c98ac7b947505cf7c48d8 100644
--- a/arch/arm64/lib/copy_in_user.S
+++ b/arch/arm64/lib/copy_in_user.S
@@ -68,7 +68,7 @@ ENTRY(raw_copy_in_user)
 	uaccess_enable_not_uao x3, x4, x5
 	add	end, x0, x2
 #include "copy_template.S"
-	uaccess_disable_not_uao x3
+	uaccess_disable_not_uao x3, x4
 	mov	x0, #0
 	ret
 ENDPROC(raw_copy_in_user)
diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S
index 318f15d5c336ccc1ae2683f612e799483336fa62..fda6172d6b88819bcec2a69439fa202c57119f40 100644
--- a/arch/arm64/lib/copy_to_user.S
+++ b/arch/arm64/lib/copy_to_user.S
@@ -66,7 +66,7 @@ ENTRY(__arch_copy_to_user)
 	uaccess_enable_not_uao x3, x4, x5
 	add	end, x0, x2
 #include "copy_template.S"
-	uaccess_disable_not_uao x3
+	uaccess_disable_not_uao x3, x4
 	mov	x0, #0
 	ret
 ENDPROC(__arch_copy_to_user)
diff --git a/arch/arm64/mm/cache.S b/arch/arm64/mm/cache.S
index 6cd20a8c0952a119b5b317377645fd17278ce025..91464e7f77cc33ff6c6d972fa38b5e92d4394e40 100644
--- a/arch/arm64/mm/cache.S
+++ b/arch/arm64/mm/cache.S
@@ -72,7 +72,7 @@ USER(9f, ic	ivau, x4	)		// invalidate I line PoU
 	isb
 	mov	x0, #0
 1:
-	uaccess_ttbr0_disable x1
+	uaccess_ttbr0_disable x1, x2
 	ret
 9:
 	mov	x0, #-EFAULT
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 05e4ae934b23025d4c5cfc5bde4c147e18a0afeb..c6a12073ef46c92e8b4f00ac071b1e683dc8f4b9 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -153,6 +153,9 @@ ENDPROC(cpu_do_resume)
 ENTRY(cpu_do_switch_mm)
 	mrs	x2, ttbr1_el1
 	mmid	x1, x1				// get mm->context.id
+#ifdef CONFIG_ARM64_SW_TTBR0_PAN
+	bfi	x0, x1, #48, #16		// set the ASID field in TTBR0
+#endif
 	bfi	x2, x1, #48, #16		// set the ASID
 	msr	ttbr1_el1, x2			// in TTBR1 (since TCR.A1 is set)
 	isb
diff --git a/arch/arm64/xen/hypercall.S b/arch/arm64/xen/hypercall.S
index acdbd2c9e899c1f87f684156244b9c1565e35efd..c5f05c4a4d00883422ed6e211135302cff3be14f 100644
--- a/arch/arm64/xen/hypercall.S
+++ b/arch/arm64/xen/hypercall.S
@@ -107,6 +107,6 @@ ENTRY(privcmd_call)
 	/*
 	 * Disable userspace access from kernel once the hyp call completed.
 	 */
-	uaccess_ttbr0_disable x6
+	uaccess_ttbr0_disable x6, x7
 	ret
 ENDPROC(privcmd_call);