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https://github.com/fergalmoran/ladybird.git
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d14d7ee78b
When booting on RPI3 firmware puts CPU in EL2 mode which is different from QEMU's default EL3. I've added logic to discover initial mode at boot and then act accordingly. This results in Serenity corectly switching to EL1 on target hardware now.
48 lines
1.0 KiB
ArmAsm
48 lines
1.0 KiB
ArmAsm
/*
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* Copyright (c) 2021, Nico Weber <thakis@chromium.org>
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* Copyright (c) 2021, Marcin Undak <mcinek@gmail.com>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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.global get_current_exception_level
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.type get_current_exception_level, @function
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get_current_exception_level:
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mrs x0, CurrentEL
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lsr x0, x0, #2
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and x0, x0, #0x3
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ret
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.global wait_cycles
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.type wait_cycles, @function
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wait_cycles:
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Lstart:
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// This is probably too fast when caching and branch prediction is turned on.
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// FIXME: Make timer-based.
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subs x0, x0, #1
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bne Lstart
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ret
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.global return_from_el2
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.type return_from_el2, @function
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return_from_el2:
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adr x0, jump_to_os_start
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msr elr_el2, x0
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eret
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.global return_from_el3
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.type return_from_el3, @function
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return_from_el3:
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adr x0, jump_to_os_start
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msr elr_el3, x0
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eret
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jump_to_os_start:
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// Let stack start before .text for now.
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// 512 kiB (0x80000) of stack are probably not sufficient, especially once we give the other cores some stack too,
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// but for now it's ok.
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ldr x14, =start
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mov sp, x14
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b os_start
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