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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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
/*
* ======================== stage_entry.S =====================================
* This file acts as an entry point to the different stages of arm64 as well as
* for the secure monitor. They share the same process of setting up stacks and
* jumping to c code. It is important to save x25 from corruption as it contains
* the argument for secure monitor.
* =============================================================================
*/
#include <arch/asm.h>
#define __ASSEMBLY__
#include <arch/lib_helpers.h>
#define STACK_SZ CONFIG_STACK_SIZE
#define EXCEPTION_STACK_SZ CONFIG_STACK_SIZE
/*
* The stacks for each of the armv8 cores grows down from _estack. It is sized
* according to MAX_CPUS. Additionally provide exception stacks for each CPU.
*/
.section .bss, "aw", @nobits
.global _stack
.global _estack
.balign STACK_SZ
_stack:
.space CONFIG_MAX_CPUS*STACK_SZ
_estack:
.global _stack_exceptions
.global _estack_exceptions
.balign EXCEPTION_STACK_SZ
_stack_exceptions:
.space CONFIG_MAX_CPUS*EXCEPTION_STACK_SZ
_estack_exceptions:
ENTRY(cpu_get_stack)
mov x1, #STACK_SZ
mul x0, x0, x1
ldr x1, 1f
sub x0, x1, x0
ret
.align 3
1:
.quad _estack
ENDPROC(cpu_get_stack)
ENTRY(cpu_get_exception_stack)
mov x1, #EXCEPTION_STACK_SZ
mul x0, x0, x1
ldr x1, 1f
sub x0, x1, x0
ret
.align 3
1:
.quad _estack_exceptions
ENDPROC(cpu_get_exception_stack)
/*
* Boot strap the processor into a C environemnt. That consists of providing
* 16-byte aligned stack. The programming enviroment uses SP_EL0 as its main
* stack while keeping SP_ELx reserved for exception entry.
*/
/*
* IMPORTANT: Ensure x25 is not corrupted because it saves the argument to
* secmon
*/
ENTRY(arm64_c_environment)
bl smp_processor_id /* x0 = cpu */
mov x24, x0
/* Set the exception stack for this cpu. */
bl cpu_get_exception_stack
msr SPSel, #1
isb
mov sp, x0
/* Have stack pointer use SP_EL0. */
msr SPSel, #0
isb
/* Set stack for this cpu. */
mov x0, x24 /* x0 = cpu */
bl cpu_get_stack
mov sp, x0
/* Get entry point by dereferencing c_entry. */
ldr x1, 1f
ldr x1, [x1]
/* Move back the arguments from x25 to x0 */
mov x0, x25
br x1
.align 3
1:
.quad c_entry
ENDPROC(arm64_c_environment)
ENTRY(__rmodule_entry)
/* Save the arguments to secmon in x25 */
mov x25, x0
b arm64_c_environment
ENDPROC(__rmodule_entry)
CPU_RESET_ENTRY(arm64_cpu_startup)
read_current x0, sctlr
bic x0, x0, #(1 << 25) /* Little Endian */
bic x0, x0, #(1 << 19) /* XN not enforced */
bic x0, x0, #(1 << 12) /* Disable Instruction Cache */
bic x0, x0, #0xf /* Clear SA, C, A, and M */
write_current sctlr, x0, x1
isb
b arm64_c_environment
ENDPROC(arm64_cpu_startup)
ENTRY(stage_entry)
b arm64_cpu_startup
ENDPROC(stage_entry)
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