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Kernel: Print current CPU exception level after booting on Aarch64

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This is a first step to switch to exception level 1.

This is also my first patch for SerenityOS :)
This commit is contained in:
Marcin Undak 2021-10-07 15:54:48 -04:00 • committed by Linus Groh
parent 7beccaf41b
commit 18eb4a59d6
4 changed files with 29 additions and 0 deletions
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12
Kernel/Prekernel/Arch/aarch64/Aarch64_asm_utils.S Normal file
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@ -0,0 +1,12 @@
/*
* Copyright (c) 2021, Marcin Undak <mcinek@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
.global get_current_exception_level
get_current_exception_level:
mrs x0, CurrentEL
lsr x0, x0, #2
and x0, x0, #0x3
ret

9
Kernel/Prekernel/Arch/aarch64/Aarch64_asm_utils.h Normal file
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@ -0,0 +1,9 @@
/*
* Copyright (c) 2021, Marcin Undak <mcinek@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
extern "C" uint8_t get_current_exception_level();

7
Kernel/Prekernel/Arch/aarch64/init.cpp
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@ -1,10 +1,12 @@
/*
* Copyright (c) 2021, Nico Weber <thakis@chromium.org>
* Copyright (c) 2021, Marcin Undak <mcinek@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Types.h>
#include <Kernel/Prekernel/Arch/aarch64/Aarch64_asm_utils.h>
#include <Kernel/Prekernel/Arch/aarch64/Mailbox.h>
#include <Kernel/Prekernel/Arch/aarch64/Timer.h>
#include <Kernel/Prekernel/Arch/aarch64/UART.h>
@ -25,6 +27,11 @@ extern "C" [[noreturn]] void init()
uart.print_num(firmware_version);
uart.print_str("\r\n");
auto exception_level = get_current_exception_level();
uart.print_str("Current CPU exception level: EL");
uart.print_num(exception_level);
uart.print_str("\r\n");
auto& timer = Prekernel::Timer::the();
u64 start_musec = 0;
for (;;) {

1
Kernel/Prekernel/CMakeLists.txt
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@ -11,6 +11,7 @@ if ("${SERENITY_ARCH}" STREQUAL "aarch64")
Arch/aarch64/MMIO.cpp
Arch/aarch64/Timer.cpp
Arch/aarch64/UART.cpp
Arch/aarch64/Aarch64_asm_utils.S
Arch/aarch64/boot.S
Arch/aarch64/init.cpp
)