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.
68 lines
1.8 KiB
C
68 lines
1.8 KiB
C
/* See the end of this file for copyright, license, and warranty information. */
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#include <arch/hardware.h>
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#include <ardix/types.h>
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#include <ardix/sched.h>
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#include <ardix/syscall.h>
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#include <errno.h>
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#include <stddef.h>
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#include <config.h>
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#ifdef CONFIG_CHECK_SYSCALL_SOURCE
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/* syscall.S */
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extern uint16_t __syscall_return_point;
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#endif
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void arch_enter(struct exc_context *context)
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{
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enum syscall number = sc_num(context);
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long (*handler)(sysarg_t arg1, sysarg_t arg2, sysarg_t arg3,
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sysarg_t arg4, sysarg_t arg5, sysarg_t arg6);
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long sc_ret;
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# ifdef CONFIG_CHECK_SYSCALL_SOURCE
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/*
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* We need to ignore the program counter's LSB because the CPU uses
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* that as a flag for whether it's operating in ARM or Thumb mode;
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* the instructions are always 2-byte aligned. Additionally, the PC
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* points to the instruction *after* the SVC, not SVC itself.
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*/
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if (((uintptr_t)regs->sp->pc & 0xfffffffe) != (uintptr_t)&__syscall_return_point) {
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sc_set_rval(regs, -EACCES);
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return;
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}
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# endif
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if (number > NSYSCALLS) {
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sc_set_rval(context, -ENOSYS);
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return;
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}
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handler = sys_table[number];
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if (handler == NULL) {
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sc_set_rval(context, -ENOSYS);
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return;
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}
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/* TODO: not every syscall uses the max amount of parameters (duh) */
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sc_ret = handler(sc_arg1(context), sc_arg2(context), sc_arg3(context),
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sc_arg4(context), sc_arg5(context), sc_arg6(context));
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sc_set_rval(context, sc_ret);
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}
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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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