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platform: generic: thead: fix stale TLB entries for th1520/sg2042

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The TLB entries remain functional all the time once added in T-HEAD th1520
and Sophgo sg2042 (even if the MMU is then disabled afterwards). If there
are some stale TLB entries that contains the address of SBI, it will cause
unexpected memory access and issue a illegal instruction error. To avoid
this, a TLB flush is needed to drop these TLB entries before any memory
access in the trap handler.

To handle this workaroud, add a custom trap handler with executing TLB flush
first in the T-HEAD platform to fix affected socs.

Signed-off-by: Inochi Amaoto <inochiama@outlook.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Inochi Amaoto
2023-09-15 17:39:36 +08:00
committed by Anup Patel
parent b7e9d34edf
commit 3669153e06
5 changed files with 78 additions and 0 deletions
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4
platform/generic/Kconfig
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@@ -52,6 +52,10 @@ config PLATFORM_STARFIVE_JH7110
bool "StarFive JH7110 support"
default n
config PLATFORM_THEAD
bool "THEAD C9xx support"
default n
source "$(OPENSBI_SRC_DIR)/platform/generic/andes/Kconfig"
endif

1
platform/generic/configs/defconfig
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@@ -4,6 +4,7 @@ CONFIG_PLATFORM_RENESAS_RZFIVE=y
CONFIG_PLATFORM_SIFIVE_FU540=y
CONFIG_PLATFORM_SIFIVE_FU740=y
CONFIG_PLATFORM_STARFIVE_JH7110=y
CONFIG_PLATFORM_THEAD=y
CONFIG_FDT_GPIO=y
CONFIG_FDT_GPIO_DESIGNWARE=y
CONFIG_FDT_GPIO_SIFIVE=y

10
platform/generic/thead/objects.mk Normal file
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@@ -0,0 +1,10 @@
#
# SPDX-License-Identifier: BSD-2-Clause
#
# Copyright (C) 2023 Inochi Amaoto <inochiama@outlook.com>
# Copyright (C) 2023 Alibaba Group Holding Limited.
#
carray-platform_override_modules-$(CONFIG_PLATFORM_THEAD) += thead_generic
platform-objs-$(CONFIG_PLATFORM_THEAD) += thead/thead-generic.o
platform-objs-$(CONFIG_PLATFORM_THEAD) += thead/thead-trap-handler.o

50
platform/generic/thead/thead-generic.c Normal file
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@@ -0,0 +1,50 @@
/*
* SPDX-License-Identifier: BSD-2-Clause
*
* Authors:
* Inochi Amaoto <inochiama@outlook.com>
*
*/
#include <platform_override.h>
#include <sbi/riscv_barrier.h>
#include <sbi/sbi_const.h>
#include <sbi/sbi_platform.h>
#include <sbi/sbi_scratch.h>
#include <sbi/sbi_string.h>
#include <sbi_utils/fdt/fdt_helper.h>
/**
* T-HEAD board with this quirk need to execute sfence.vma to flush
* stale entrie avoid incorrect memory access.
*/
#define THEAD_QUIRK_TLB_FLUSH_FIXUP BIT(0)
void _thead_tlb_flush_fixup_trap_handler(void);
void thead_register_tlb_flush_trap_handler(void)
{
csr_write(CSR_MTVEC, &_thead_tlb_flush_fixup_trap_handler);
}
static int thead_generic_early_init(bool cold_boot,
const struct fdt_match *match)
{
unsigned long quirks = (unsigned long)match->data;
if (quirks & THEAD_QUIRK_TLB_FLUSH_FIXUP)
thead_register_tlb_flush_trap_handler();
return 0;
}
static const struct fdt_match thead_generic_match[] = {
{ .compatible = "thead,th1520",
.data = (void*)THEAD_QUIRK_TLB_FLUSH_FIXUP },
{ },
};
const struct platform_override thead_generic = {
.match_table = thead_generic_match,
.early_init = thead_generic_early_init,
};

13
platform/generic/thead/thead-trap-handler.S Normal file
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@@ -0,0 +1,13 @@
/*
* SPDX-License-Identifier: BSD-2-Clause
*
* Authors:
* Inochi Amaoto <inochiama@outlook.com>
*
*/
.section .entry, "ax", %progbits
.align 3
.globl _thead_tlb_flush_fixup_trap_handler
_thead_tlb_flush_fixup_trap_handler:
sfence.vma t0, zero
j _trap_handler