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/*
* This file is part of the coreboot project.
*
* Copyright 2014 Google Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
/*
* transition_asm.S: This file handles the entry and exit from an exception
*
* Flow: exception --> exc_vectors --> exc_entry --> exc_dispatch -->
* exc_exit
* Transition Flow: transition --> trans_switch --> exc_exit
*
* |---| Exception Entry |---|
*
* On exception entry, it saves all the xregs on SP_ELx since SP_ELx is
* selected on entry. Some dummy pushes are performed to create space for
* elx_state structure. It then passes pointer to this saved set of regs and
* a unique id(for identifying exception) to exc_entry.
*
* |---| Exception Transition Dispatch |---|
*
* This is the C-component of exception entry. It does the work of initializing
* the exc_state registers. Finally it calls exception dispatch implemented by
* the user. This is point of no-return.
*
* |---| Exception Dispatch |---|
*
* User of this functionality is expected to implement exc_dispatch which
* acts as entry point for it. Once exception handling is complete, the user
* needs to call exc_exit with pointer to struct regs.
*
* |---| Exception Exit |---|
*
* Once exc_dispatch is done with handling the exception based on the id passed
* to it, it needs to call exc_exit with pointer to struct regs. This is done to
* unwind the exception stack by popping off all the xregs.
*
* |---| Exception Transition Exit |---|
*
* This routine makes SP_EL0 point to the regs structure passed and continues
* onto the exception exit routine described above. This is the reason that
* transition library does not handle initialization of SP_EL0 for the program
* to be executed.
*/
#define __ASSEMBLY__
#include <arch/asm.h>
#include <arch/lib_helpers.h>
#include <arch/transition.h>
.macro eentry lbl id
.align 7
\lbl:
stp x29, x30, [sp, #STACK_PUSH_BYTES]!
bl exc_prologue
mov x1, \id
mov x0, sp
b exc_entry
.endm
/*
* exc_vectors: Entry point for an exception
*/
ENTRY_WITH_ALIGN(exc_vectors, 11)
eentry sync_curr_sp0, #EXC_VID_CUR_SP_EL0_SYNC
eentry irq_curr_sp0, #EXC_VID_CUR_SP_EL0_IRQ
eentry fiq_curr_sp0, #EXC_VID_CUR_SP_EL0_FIRQ
eentry serror_curr_sp0, #EXC_VID_CUR_SP_EL0_SERR
eentry sync_curr_spx, #EXC_VID_CUR_SP_ELX_SYNC
eentry irq_curr_spx, #EXC_VID_CUR_SP_ELX_IRQ
eentry fiq_curr_spx, #EXC_VID_CUR_SP_ELX_FIQ
eentry serror_curr_spx, #EXC_VID_CUR_SP_ELX_SERR
eentry sync_lower_64, #EXC_VID_LOW64_SYNC
eentry irq_lower_64, #EXC_VID_LOW64_IRQ
eentry fiq_lower_64, #EXC_VID_LOW64_FIQ
eentry serror_lower_64, #EXC_VID_LOW64_SERR
eentry sync_lower_32, #EXC_VID_LOW32_SYNC
eentry irq_lower_32, #EXC_VID_LOW32_IRQ
eentry fiq_lower_32, #EXC_VID_LOW32_FIQ
eentry serror_lower_32, #EXC_VID_LOW32_SERR
ENDPROC(exc_vectors)
ENTRY(exc_prologue)
stp x27, x28, [sp, #STACK_PUSH_BYTES]!
stp x25, x26, [sp, #STACK_PUSH_BYTES]!
stp x23, x24, [sp, #STACK_PUSH_BYTES]!
stp x21, x22, [sp, #STACK_PUSH_BYTES]!
stp x19, x20, [sp, #STACK_PUSH_BYTES]!
stp x17, x18, [sp, #STACK_PUSH_BYTES]!
stp x15, x16, [sp, #STACK_PUSH_BYTES]!
stp x13, x14, [sp, #STACK_PUSH_BYTES]!
stp x11, x12, [sp, #STACK_PUSH_BYTES]!
stp x9, x10, [sp, #STACK_PUSH_BYTES]!
stp x7, x8, [sp, #STACK_PUSH_BYTES]!
stp x5, x6, [sp, #STACK_PUSH_BYTES]!
stp x3, x4, [sp, #STACK_PUSH_BYTES]!
stp x1, x2, [sp, #STACK_PUSH_BYTES]!
/* xzr pushed as place holder for sp */
stp xzr, x0, [sp, #STACK_PUSH_BYTES]!
/*
* xzr pushed as place holder for:
* 1. sp_elx and elr
*/
stp xzr, xzr, [sp, #STACK_PUSH_BYTES]!
/* 2. spsr and sp_el0 */
stp xzr, xzr, [sp, #STACK_PUSH_BYTES]!
ret
ENDPROC(exc_prologue)
/*
* trans_switch: Set SPSel to use SP_EL0
* x0 = regs structure
*/
ENTRY(trans_switch)
msr SPSel, #SPSR_USE_L
b exc_exit
ENDPROC(trans_switch)
/*
* exc_exit: Return from exception by restoring saved state of xregs
* x0 = regs structure
*/
ENTRY(exc_exit)
/* Unwind the stack by making sp point to regs structure */
mov sp, x0
/* Load registers x0-x30 */
ldp xzr, x0, [sp], #STACK_POP_BYTES
ldp x1, x2, [sp], #STACK_POP_BYTES
ldp x3, x4, [sp], #STACK_POP_BYTES
ldp x5, x6, [sp], #STACK_POP_BYTES
ldp x7, x8, [sp], #STACK_POP_BYTES
ldp x9, x10, [sp], #STACK_POP_BYTES
ldp x11, x12, [sp], #STACK_POP_BYTES
ldp x13, x14, [sp], #STACK_POP_BYTES
ldp x15, x16, [sp], #STACK_POP_BYTES
ldp x17, x18, [sp], #STACK_POP_BYTES
ldp x19, x20, [sp], #STACK_POP_BYTES
ldp x21, x22, [sp], #STACK_POP_BYTES
ldp x23, x24, [sp], #STACK_POP_BYTES
ldp x25, x26, [sp], #STACK_POP_BYTES
ldp x27, x28, [sp], #STACK_POP_BYTES
ldp x29, x30, [sp], #STACK_POP_BYTES
eret
ENDPROC(exc_exit)
/*
* exception_init_asm: Initialize VBAR and point SP_EL3 to exception stack.
* x0 = end of exception stack
*/
ENTRY(exception_init_asm)
msr SPSel, #SPSR_USE_H
mov sp, x0
msr SPSel, #SPSR_USE_L
adr x0, exc_vectors
write_current vbar, x0, x1
dsb sy
isb
ret
ENDPROC(exception_init_asm)
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