/*
* 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
