Build option to include AArch32 registers in cpu context
The system registers that are saved and restored in CPU context include
AArch32 systems registers like SPSR_ABT, SPSR_UND, SPSR_IRQ, SPSR_FIQ,
DACR32_EL2, IFSR32_EL2 and FPEXC32_EL2. Accessing these registers on an
AArch64-only (i.e. on hardware that does not implement AArch32, or at
least not at EL1 and higher ELs) platform leads to an exception. This patch
introduces the build option `CTX_INCLUDE_AARCH32_REGS` to specify whether to
include these AArch32 systems registers in the cpu context or not. By default
this build option is set to 1 to ensure compatibility. AArch64-only platforms
must set it to 0. A runtime check is added in BL1 and BL31 cold boot path to
verify this.
Fixes ARM-software/tf-issues#386
Change-Id: I720cdbd7ed7f7d8516635a2ec80d025f478b95ee
diff --git a/bl31/bl31_main.c b/bl31/bl31_main.c
index 835d41e..7f04d21 100644
--- a/bl31/bl31_main.c
+++ b/bl31/bl31_main.c
@@ -145,6 +145,19 @@
entry_point_info_t *next_image_info;
uint32_t image_type;
+#if CTX_INCLUDE_AARCH32_REGS
+ /*
+ * Ensure that the build flag to save AArch32 system registers in CPU
+ * context is not set for AArch64-only platforms.
+ */
+ if (((read_id_aa64pfr0_el1() >> ID_AA64PFR0_EL1_SHIFT)
+ & ID_AA64PFR0_ELX_MASK) == 0x1) {
+ ERROR("EL1 supports AArch64-only. Please set build flag "
+ "CTX_INCLUDE_AARCH32_REGS = 0");
+ panic();
+ }
+#endif
+
/* Determine which image to execute next */
image_type = bl31_get_next_image_type();