--- zzzz-none-000/linux-4.4.271/arch/arm/mm/proc-v7-3level.S	2021-06-03 06:22:09.000000000 +0000
+++ hawkeye-5590-750/linux-4.4.271/arch/arm/mm/proc-v7-3level.S	2023-04-19 10:22:27.000000000 +0000
@@ -65,6 +65,37 @@
 	ret	lr
 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	r2, r2
+	asid	r2, r2
+	orr	rpgdh, rpgdh, r2, lsl #(48 - 32)	@ upper 32-bits of pgd
+	mcrr	p15, 0, rpgdl, rpgdh, c2		@ set TTB 0
+	isb
+#endif
+	pop	{pc}
+ENDPROC(cpu_krait_switch_mm)
+
 #ifdef __ARMEB__
 #define rl r3
 #define rh r2