ARM: Introduce erratum workaround for 454179
454179: Stale prediction may inhibit target address misprediction on
next predicted taken branch
Impacts: Every Cortex-A8 processors with revision lower than r2p1
Work around: Set IBE and disable branch size mispredict to 1
Also provide a hook for SoC specific handling to take place if needed.
Based on ARM errata Document revision 20.0 (13 Nov 2010)
Signed-off-by: Nishanth Menon <nm@ti.com>
Tested-by: Matt Porter <mporter@konsulko.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
index 89637e2..8483687 100644
--- a/arch/arm/cpu/armv7/start.S
+++ b/arch/arm/cpu/armv7/start.S
@@ -189,6 +189,19 @@
skip_errata_798870:
#endif
+#ifdef CONFIG_ARM_ERRATA_454179
+ cmp r2, #0x21 @ Only on < r2p1
+ bge skip_errata_454179
+
+ mrc p15, 0, r0, c1, c0, 1 @ Read ACR
+ orr r0, r0, #(0x3 << 6) @ Set DBSM(BIT7) and IBE(BIT6) bits
+ push {r1-r5} @ Save the cpu info registers
+ bl v7_arch_cp15_set_acr
+ pop {r1-r5} @ Restore the cpu info - fall through
+
+skip_errata_454179:
+#endif
+
mov pc, r5 @ back to my caller
ENDPROC(cpu_init_cp15)