arm_fpga: Add support for unknown MPIDs
This patch allows the system to fallback to a default CPU library
in case the MPID does not match with any of the supported ones.
This feature can be enabled by setting SUPPORT_UNKNOWN_MPID build
option to 1 (enabled by default only on arm_fpga platform).
This feature can be very dangerous on a production image and
therefore it MUST be disabled for Release images.
Signed-off-by: Javier Almansa Sobrino <javier.almansasobrino@arm.com>
Change-Id: I0df7ef2b012d7d60a4fd5de44dea1fbbb46881ba
diff --git a/lib/cpus/aarch64/cpu_helpers.S b/lib/cpus/aarch64/cpu_helpers.S
index da663be..730b09b 100644
--- a/lib/cpus/aarch64/cpu_helpers.S
+++ b/lib/cpus/aarch64/cpu_helpers.S
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2014-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2014-2020, Arm Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
@@ -140,6 +140,13 @@
* midr of the core. It reads the MIDR_EL1 and finds the matching
* entry in cpu_ops entries. Only the implementation and part number
* are used to match the entries.
+ *
+ * If cpu_ops for the MIDR_EL1 cannot be found and
+ * SUPPORT_UNKNOWN_MPID is enabled, it will try to look for a
+ * default cpu_ops with an MIDR value of 0.
+ * (Implementation number 0x0 should be reseverd for software use
+ * and therefore no clashes should happen with that default value).
+ *
* Return :
* x0 - The matching cpu_ops pointer on Success
* x0 - 0 on failure.
@@ -147,23 +154,26 @@
*/
.globl get_cpu_ops_ptr
func get_cpu_ops_ptr
- /* Get the cpu_ops start and end locations */
- adr x4, (__CPU_OPS_START__ + CPU_MIDR)
- adr x5, (__CPU_OPS_END__ + CPU_MIDR)
-
- /* Initialize the return parameter */
- mov x0, #0
-
/* Read the MIDR_EL1 */
mrs x2, midr_el1
mov_imm x3, CPU_IMPL_PN_MASK
/* Retain only the implementation and part number using mask */
and w2, w2, w3
+
+ /* Get the cpu_ops end location */
+ adr x5, (__CPU_OPS_END__ + CPU_MIDR)
+
+ /* Initialize the return parameter */
+ mov x0, #0
1:
+ /* Get the cpu_ops start location */
+ adr x4, (__CPU_OPS_START__ + CPU_MIDR)
+
+2:
/* Check if we have reached end of list */
cmp x4, x5
- b.eq error_exit
+ b.eq search_def_ptr
/* load the midr from the cpu_ops */
ldr x1, [x4], #CPU_OPS_SIZE
@@ -171,7 +181,7 @@
/* Check if midr matches to midr of this core */
cmp w1, w2
- b.ne 1b
+ b.ne 2b
/* Subtract the increment and offset to get the cpu-ops pointer */
sub x0, x4, #(CPU_OPS_SIZE + CPU_MIDR)
@@ -179,7 +189,27 @@
cmp x0, #0
ASM_ASSERT(ne)
#endif
+#ifdef SUPPORT_UNKNOWN_MPID
+ cbnz x2, exit_mpid_found
+ /* Mark the unsupported MPID flag */
+ adrp x1, unsupported_mpid_flag
+ add x1, x1, :lo12:unsupported_mpid_flag
+ str w2, [x1]
+exit_mpid_found:
+#endif
+ ret
+
+ /*
+ * Search again for a default pointer (MIDR = 0x0)
+ * or return error if already searched.
+ */
+search_def_ptr:
+#ifdef SUPPORT_UNKNOWN_MPID
+ cbz x2, error_exit
+ mov x2, #0
+ b 1b
error_exit:
+#endif
ret
endfunc get_cpu_ops_ptr