lib: ramdetect: Register exception handlers for ARMv8

Register exception handlers to avoid a Synchronous External Abort
that is raised when you try to access a non-memory address on ARMv8.
An exception handler can jump over the faulting instruction.
This is the feature only for QEMU/AArch64.

Signed-off-by: Asami Doi <d0iasm.pub@gmail.com>
Change-Id: I09a306ca307ba4027d9758c3debc2e7c844c66b8
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34774
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
This commit is contained in:
Asami Doi 2019-08-07 13:40:53 +09:00 committed by Patrick Georgi
parent b0b99058cc
commit 06993ee729
4 changed files with 50 additions and 1 deletions

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@ -107,6 +107,7 @@ romstage-$(CONFIG_ARM64_USE_ARCH_TIMER) += arch_timer.c
romstage-y += memset.S
romstage-y += memcpy.S
romstage-y += memmove.S
romstage-y += ramdetect.c
romstage-y += romstage.c
romstage-y += transition.c transition_asm.S
@ -131,6 +132,7 @@ ramstage-y += div0.c
ramstage-y += eabi_compat.c
ramstage-y += boot.c
ramstage-y += tables.c
ramstage-y += ramdetect.c
ramstage-$(CONFIG_ARM64_USE_ARCH_TIMER) += arch_timer.c
ramstage-y += memset.S
ramstage-y += memcpy.S

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@ -0,0 +1,41 @@
/*
* This file is part of the coreboot project.
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include <types.h>
#include <device/mmio.h>
#include <ramdetect.h>
#include <arch/exception.h>
#include <arch/transition.h>
static enum {
ABORT_CHECKER_NOT_TRIGGERED,
ABORT_CHECKER_TRIGGERED,
} abort_state = ABORT_CHECKER_NOT_TRIGGERED;
static int abort_checker(struct exc_state *state, uint64_t vector_id)
{
if (raw_read_esr_el3() >> 26 != 0x25)
return EXC_RET_IGNORED; /* Not a data abort. */
abort_state = ABORT_CHECKER_TRIGGERED;
state->elx.elr += sizeof(uint32_t); /* Jump over faulting instruction. */
raw_write_elr_el3(state->elx.elr);
return EXC_RET_HANDLED;
}
static struct exception_handler sync_el0 = {.handler = &abort_checker};
int probe_mb(const uintptr_t dram_start, const uintptr_t size)
{
uintptr_t addr = dram_start + (size * MiB) - sizeof(uint32_t);
void *ptr = (void *)addr;
abort_state = ABORT_CHECKER_NOT_TRIGGERED;
exception_handler_register(EXC_VID_CUR_SP_EL0_SYNC, &sync_el0);
read32(ptr);
exception_handler_unregister(EXC_VID_CUR_SP_EL0_SYNC, &sync_el0);
return abort_state == ABORT_CHECKER_NOT_TRIGGERED;
}

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@ -11,6 +11,12 @@
* GNU General Public License for more details.
*/
/*
* Used in probe_ramsize(). This is a weak function and it's overridden for
* ARMv8. Return 1 when DRAM exists at the address, otherwise return 0.
*/
int probe_mb(const uintptr_t dram_start, const uintptr_t size);
/*
* Probe an area if it's read/writable.
* Primary use case is the detection of DRAM amount on emulators.

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@ -19,7 +19,7 @@
#define OVERLAP(a, b, s, e) ((b) > (s) && (a) < (e))
static int probe_mb(const uintptr_t dram_start, const uintptr_t size)
int __weak probe_mb(const uintptr_t dram_start, const uintptr_t size)
{
uintptr_t addr = dram_start + (size * MiB) - sizeof(uint32_t);
static const uint32_t patterns[] = {