Disable speculative loads only if SSBS is supported
Examine the ID_AA64PFR1_EL1 bits 7:4 to see if speculative
loads (SSBS) is implemented, before disabling speculative
loads.
Change-Id: I7607c45ed2889260d22a94f6fd9af804520acf67
Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
diff --git a/lib/cpus/aarch64/neoverse_n1.S b/lib/cpus/aarch64/neoverse_n1.S
index 2038f31..a0babb0 100644
--- a/lib/cpus/aarch64/neoverse_n1.S
+++ b/lib/cpus/aarch64/neoverse_n1.S
@@ -49,11 +49,31 @@
b cpu_rev_var_ls
endfunc check_errata_1043202
+/* --------------------------------------------------
+ * Disable speculative loads if Neoverse N1 supports
+ * SSBS.
+ *
+ * Shall clobber: x0.
+ * --------------------------------------------------
+ */
+func neoverse_n1_disable_speculative_loads
+ /* Check if the PE implements SSBS */
+ mrs x0, id_aa64pfr1_el1
+ tst x0, #(ID_AA64PFR1_EL1_SSBS_MASK << ID_AA64PFR1_EL1_SSBS_SHIFT)
+ b.eq 1f
+
+ /* Disable speculative loads */
+ msr SSBS, xzr
+ isb
+
+1:
+ ret
+endfunc neoverse_n1_disable_speculative_loads
+
func neoverse_n1_reset_func
mov x19, x30
- /* Disables speculative loads */
- msr SSBS, xzr
+ bl neoverse_n1_disable_speculative_loads
/* Forces all cacheable atomic instructions to be near */
mrs x0, NEOVERSE_N1_CPUACTLR2_EL1