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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
*/
#include <arch/lib_helpers.h>
#include <arch/transition.h>
#include <console/console.h>
/* Mask out debug exceptions, serror, irq and fiq */
#define SPSR_MASK (SPSR_FIQ_MASK | SPSR_IRQ_MASK | SPSR_SERROR_MASK | \
SPSR_DEBUG_MASK)
/* Litte-endian, No XN-forced, Instr cache disabled,
* Stack alignment disabled, Data and unified cache
* disabled, Alignment check disabled, MMU disabled
*/
#define SCTLR_MASK (SCTLR_MMU_DISABLE | SCTLR_ACE_DISABLE | \
SCTLR_CACHE_DISABLE | SCTLR_SAE_DISABLE | SCTLR_RES1 | \
SCTLR_ICE_DISABLE | SCTLR_WXN_DISABLE | SCTLR_LITTLE_END)
void __attribute__((weak)) exc_dispatch(struct exc_state *exc_state, uint64_t id)
{
/* Default weak implementation does nothing. */
}
void exc_entry(struct exc_state *exc_state, uint64_t id)
{
struct elx_state *elx = &exc_state->elx;
struct regs *regs = &exc_state->regs;
uint8_t elx_mode, elx_el;
elx->spsr = raw_read_spsr_current();
elx_mode = get_mode_from_spsr(elx->spsr);
elx_el = get_el_from_spsr(elx->spsr);
if (elx_mode == SPSR_USE_H) {
if (elx_el == get_current_el())
regs->sp = (uint64_t)&exc_state[1];
else
regs->sp = raw_read_sp_elx(elx_el);
} else {
regs->sp = raw_read_sp_el0();
}
elx->elr = raw_read_elr_current();
exc_dispatch(exc_state, id);
}
void transition_with_entry(void *entry, void *arg, struct exc_state *exc_state)
{
/* Argument to entry point goes into X0 */
exc_state->regs.x[X0_INDEX] = (uint64_t)arg;
/* Entry point goes into ELR */
exc_state->elx.elr = (uint64_t)entry;
transition(exc_state);
}
void transition(struct exc_state *exc_state)
{
uint32_t scr_mask;
uint64_t hcr_mask;
uint64_t sctlr;
uint32_t current_el = get_current_el();
struct elx_state *elx = &exc_state->elx;
struct regs *regs = &exc_state->regs;
uint8_t elx_el = get_el_from_spsr(elx->spsr);
/*
* Policies enforced:
* 1. We support only elx --> (elx - 1) transitions
* 2. We support transitions to Aarch64 mode only
*
* If any of the above conditions holds false, then we need a proper way
* to update SCR/HCR before removing the checks below
*/
if ((current_el - elx_el) != 1)
die("ARM64 Error: Do not support transition\n");
if (elx->spsr & SPSR_ERET_32)
die("ARM64 Error: Do not support eret to Aarch32\n");
else {
scr_mask = SCR_LOWER_AARCH64;
hcr_mask = HCR_LOWER_AARCH64;
}
/* SPSR: Mask out debug exceptions, serror, irq, fiq */
elx->spsr |= SPSR_MASK;
raw_write_spsr_current(elx->spsr);
/* SCR: Write to SCR if current EL is EL3 */
if (current_el == EL3) {
uint32_t scr = raw_read_scr_el3();
scr |= scr_mask;
raw_write_scr_el3(scr);
}
/* HCR: Write to HCR if current EL is EL2 */
else if (current_el == EL2) {
uint64_t hcr = raw_read_hcr_el2();
hcr |= hcr_mask;
raw_write_hcr_el2(hcr);
}
/* ELR: Write entry point of program */
raw_write_elr_current(elx->elr);
/* SCTLR: Initialize EL with selected properties */
sctlr = raw_read_sctlr(elx_el);
sctlr &= SCTLR_MASK;
raw_write_sctlr(sctlr, elx_el);
/* SP_ELx: Initialize stack pointer */
raw_write_sp_elx(elx->sp_elx, elx_el);
/* Eret to the entry point */
trans_switch(regs);
}
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