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/* SPDX-License-Identifier: copyleft-next-0.3.1 */
/* Copyright 2021 - 2022, Kim Kuparinen < kimi.h.kuparinen@gmail.com > */
/**
* @file proc.c
* riscv64 implementation of arch-specific process handling.
*/
#include <kmi/tcb.h>
#include <kmi/elf.h>
#include <kmi/bkl.h>
#include <kmi/debug.h>
#include <kmi/string.h>
#include <arch/proc.h>
#include "regs.h"
#include "csr.h"
/** Assembly implementation for actually jumping to the init process, defined in
* start.S. Quite a few constants that could be implemented in assembly as well
* but this is maybe a bit more convenient.
*
* @param pid Should always be 0 to indicate that the kernel is the originator.
* @param tid Thread ID of the current thread.
* @param code Should always be SYS_USER_SPAWNED to indicate that a new core has
* come online.
* @param fdt Address of flattened device tree within userspace memory.
* @param initrd Ditto for initial ramdisk.
* @param proc Process ID, should be constant 1.
* @param stack_top Stack address.
*/
__noreturn void riscv_run_init(sys_arg_t pid,
sys_arg_t tid,
sys_arg_t code,
sys_arg_t fdt,
sys_arg_t initrd,
sys_arg_t proc, /* not strictly speaking necessary but eh */
sys_arg_t stack_top);
void run_init(struct tcb *t, vm_t fdt, vm_t initrd)
{
csr_write(CSR_SSCRATCH, t);
csr_write(CSR_SEPC, t->callback);
/* gcc gives a warning 'the value of the stack pointer after an asm
* statement must be the same as it was before the statement', so this
* is technically speaking undefined behavior, I think.
*
* Could be fixed with a separate pure asm run_init, but I guess this
* works for now.
*/
vm_t stack_top = t->thread_stack + t->thread_stack_size;
info("jumping to %lx\n", (long)t->callback);
bkl_unlock();
riscv_run_init(0, t->tid, SYS_USER_SPAWNED, fdt, initrd, 1, stack_top);
/* we should never reach this */
unreachable();
}
void set_args(struct tcb *t, size_t n, struct sys_ret a)
{
struct riscv_regs *r = (struct riscv_regs *)(t->regs) - 1;
if (n >= 1) r->a0 = a.s;
if (n >= 2) r->a1 = a.ar0;
if (n >= 3) r->a2 = a.ar1;
if (n >= 4) r->a3 = a.ar2;
if (n >= 5) r->a4 = a.ar3;
if (n >= 6) r->a5 = a.ar4;
}
struct sys_ret get_args(struct tcb *t)
{
struct riscv_regs *r = (struct riscv_regs *)(t->regs) - 1;
return SYS_RET6(r->a0, r->a1, r->a2, r->a3, r->a4, r->a5);
}
void set_thread(struct tcb *t)
{
/* get location of registers in memory */
/** \todo check alignment, should be fine but just to be sure */
struct riscv_regs *r = (struct riscv_regs *)(t->regs) - 1;
/* insert important values into register slots */
r->sp = (long)t->thread_stack + t->thread_stack_size;
}
void set_stack(struct tcb *t, vm_t s)
{
/** @todo also set frame pointer on architectures that need it? */
struct riscv_regs *r = (struct riscv_regs *)(t->regs) - 1;
r->sp = s;
}
vm_t get_stack(struct tcb *t)
{
struct riscv_regs *r = (struct riscv_regs *)(t->regs) - 1;
return r->sp;
}
void copy_regs(struct tcb *d, struct tcb *s)
{
struct riscv_regs *rd = (struct riscv_regs *)(d->regs) - 1;
struct riscv_regs *rs = (struct riscv_regs *)(s->regs) - 1;
*rd = *rs;
}
void adjust_ipi(struct tcb *t)
{
UNUSED(t);
}
void adjust_syscall(struct tcb *t)
{
t->exec += 4;
}
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