fef
7e6dbad05f
The old strategy was to only do context switching from within the PendSV handler. This worked fine until now because all syscalls were handled either atomically or just returned -EAGAIN if the resource was locked or busy. However, with the introduction of I/O wait, we need to be able to sleep directly from within the kernel by moving the context switching completely into the kernel.
33 lines
937 B
ArmAsm
33 lines
937 B
ArmAsm
/* See the end of this file for copyright, license, and warranty information. */
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.include "asm.S"
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.text
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/* void _do_switch(struct context *old, struct context *new); */
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func_begin _do_switch
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/* ldm/stm can't use sp in the reglist, we need to store it individually */
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stmia r0!, {r4-r11}
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str sp, [r0]
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str lr, [r0, #4] /* this becomes pc when we are switched back to */
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ldmia r1!, {r4-r11}
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ldr sp, [r1]
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ldr pc, [r1, #4] /* this is the lr that we stored */
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func_end _do_switch
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/*
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* This file is part of Ardix.
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* Copyright (c) 2020, 2021 Felix Kopp <owo@fef.moe>.
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*
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* Ardix is non-violent software: you may only use, redistribute,
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* and/or modify it under the terms of the CNPLv6+ as found in
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* the LICENSE file in the source code root directory or at
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* <https://git.pixie.town/thufie/CNPL>.
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*
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* Ardix comes with ABSOLUTELY NO WARRANTY, to the extent
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* permitted by applicable law. See the CNPLv6+ for details.
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*/
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