--- zzzz-none-000/linux-4.4.271/arch/arm/mm/proc-v7-2level.S	2021-06-03 06:22:09.000000000 +0000
+++ hawkeye-5590-750/linux-4.4.271/arch/arm/mm/proc-v7-2level.S	2023-04-19 10:22:27.000000000 +0000
@@ -63,6 +63,47 @@
 ENDPROC(cpu_v7_switch_mm)
 
 /*
+ * Qualcomm Technologies Inc. Krait processors - require bp invalidation
+ */
+ENTRY(cpu_krait_switch_mm)
+/* Sanitize link stack
+ * The below instrucitons will cause lr to be loaded with a value
+ * which will never be used, thus nullyfying branch prediction based
+ * attacks
+ */
+	push	{lr}
+	bl	1f
+1:	bl	1f
+1:	bl	1f
+1:	bl	1f
+1:	bl	1f
+1:	bl	1f
+1:	bl	1f
+1:	bl	1f
+1:	mov     lr, #0
+	mcr     p15, 0, lr, c7, c5, 6   @ BPIALL
+	isb
+#ifdef CONFIG_MMU
+	mmid	r1, r1				@ get mm->context.id
+	ALT_SMP(orr	r0, r0, #TTB_FLAGS_SMP)
+	ALT_UP(orr	r0, r0, #TTB_FLAGS_UP)
+#ifdef CONFIG_PID_IN_CONTEXTIDR
+	mrc	p15, 0, r2, c13, c0, 1		@ read current context ID
+	lsr	r2, r2, #8			@ extract the PID
+	bfi	r1, r2, #8, #24			@ insert into new context ID
+#endif
+#ifdef CONFIG_ARM_ERRATA_754322
+	dsb
+#endif
+	mcr	p15, 0, r1, c13, c0, 1		@ set context ID
+	isb
+	mcr	p15, 0, r0, c2, c0, 0		@ set TTB 0
+	isb
+#endif
+	pop	{pc}
+ENDPROC(cpu_krait_switch_mm)
+
+/*
  *	cpu_v7_set_pte_ext(ptep, pte)
  *
  *	Set a level 2 translation table entry.