RAS: Move EA handling to a separate file
A new file ea_delegate.S is introduced, and all EA-related functions are
moved into it. This makes runtime_exceptions.S less crowded and reads
better.
No functional changes.
Change-Id: I64b653b3931984cffd420563f8e8d1ba263f329f
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
diff --git a/bl31/aarch64/ea_delegate.S b/bl31/aarch64/ea_delegate.S
new file mode 100644
index 0000000..dce1f5a
--- /dev/null
+++ b/bl31/aarch64/ea_delegate.S
@@ -0,0 +1,163 @@
+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+
+#include <asm_macros.S>
+#include <context.h>
+#include <ea_handle.h>
+
+
+ .globl handle_lower_el_ea_esb
+ .globl enter_lower_el_sync_ea
+ .globl enter_lower_el_async_ea
+
+
+/*
+ * Function to delegate External Aborts synchronized by ESB instruction at EL3
+ * vector entry. This function assumes GP registers x0-x29 have been saved, and
+ * are available for use. It delegates the handling of the EA to platform
+ * handler, and returns only upon successfully handling the EA; otherwise
+ * panics. On return from this function, the original exception handler is
+ * expected to resume.
+ */
+func handle_lower_el_ea_esb
+ mov x0, #ERROR_EA_ESB
+ mrs x1, DISR_EL1
+ b ea_proceed
+endfunc handle_lower_el_ea_esb
+
+
+/*
+ * This function forms the tail end of Synchronous Exception entry from lower
+ * EL, and expects to handle only Synchronous External Aborts from lower EL. If
+ * any other kind of exception is detected, then this function reports unhandled
+ * exception.
+ *
+ * Since it's part of exception vector, this function doesn't expect any GP
+ * registers to have been saved. It delegates the handling of the EA to platform
+ * handler, and upon successfully handling the EA, exits EL3; otherwise panics.
+ */
+func enter_lower_el_sync_ea
+ /*
+ * Explicitly save x30 so as to free up a register and to enable
+ * branching.
+ */
+ str x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR]
+
+ mrs x30, esr_el3
+ ubfx x30, x30, #ESR_EC_SHIFT, #ESR_EC_LENGTH
+
+ /* Check for I/D aborts from lower EL */
+ cmp x30, #EC_IABORT_LOWER_EL
+ b.eq 1f
+
+ cmp x30, #EC_DABORT_LOWER_EL
+ b.ne 2f
+
+1:
+ /* Test for EA bit in the instruction syndrome */
+ mrs x30, esr_el3
+ tbz x30, #ESR_ISS_EABORT_EA_BIT, 2f
+
+ /* Save GP registers */
+ bl save_gp_registers
+
+ /* Setup exception class and syndrome arguments for platform handler */
+ mov x0, #ERROR_EA_SYNC
+ mrs x1, esr_el3
+ adr x30, el3_exit
+ b ea_proceed
+
+2:
+ /* Synchronous exceptions other than the above are assumed to be EA */
+ ldr x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR]
+ no_ret report_unhandled_exception
+endfunc enter_lower_el_sync_ea
+
+
+/*
+ * This function handles SErrors from lower ELs.
+ *
+ * Since it's part of exception vector, this function doesn't expect any GP
+ * registers to have been saved. It delegates the handling of the EA to platform
+ * handler, and upon successfully handling the EA, exits EL3; otherwise panics.
+ */
+func enter_lower_el_async_ea
+ /*
+ * Explicitly save x30 so as to free up a register and to enable
+ * branching
+ */
+ str x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR]
+
+ /* Save GP registers */
+ bl save_gp_registers
+
+ /* Setup exception class and syndrome arguments for platform handler */
+ mov x0, #ERROR_EA_ASYNC
+ mrs x1, esr_el3
+ adr x30, el3_exit
+ b ea_proceed
+endfunc enter_lower_el_async_ea
+
+
+/*
+ * Delegate External Abort handling to platform's EA handler. This function
+ * assumes that all GP registers have been saved by the caller.
+ *
+ * x0: EA reason
+ * x1: EA syndrome
+ */
+func ea_proceed
+ /* Save EL3 state */
+ mrs x2, spsr_el3
+ mrs x3, elr_el3
+ stp x2, x3, [sp, #CTX_EL3STATE_OFFSET + CTX_SPSR_EL3]
+
+ /*
+ * Save ESR as handling might involve lower ELs, and returning back to
+ * EL3 from there would trample the original ESR.
+ */
+ mrs x4, scr_el3
+ mrs x5, esr_el3
+ stp x4, x5, [sp, #CTX_EL3STATE_OFFSET + CTX_SCR_EL3]
+
+ /*
+ * Setup rest of arguments, and call platform External Abort handler.
+ *
+ * x0: EA reason (already in place)
+ * x1: Exception syndrome (already in place).
+ * x2: Cookie (unused for now).
+ * x3: Context pointer.
+ * x4: Flags (security state from SCR for now).
+ */
+ mov x2, xzr
+ mov x3, sp
+ ubfx x4, x4, #0, #1
+
+ /* Switch to runtime stack */
+ ldr x5, [sp, #CTX_EL3STATE_OFFSET + CTX_RUNTIME_SP]
+ msr spsel, #0
+ mov sp, x5
+
+ mov x29, x30
+ bl plat_ea_handler
+ mov x30, x29
+
+ /* Make SP point to context */
+ msr spsel, #1
+
+ /* Restore EL3 state */
+ ldp x1, x2, [sp, #CTX_EL3STATE_OFFSET + CTX_SPSR_EL3]
+ msr spsr_el3, x1
+ msr elr_el3, x2
+
+ /* Restore ESR_EL3 and SCR_EL3 */
+ ldp x3, x4, [sp, #CTX_EL3STATE_OFFSET + CTX_SCR_EL3]
+ msr scr_el3, x3
+ msr esr_el3, x4
+
+ ret
+endfunc ea_proceed