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path: root/src/kernel/execbuf.c
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#include <kernel/execbuf.h>
#include <kernel/mem/alloc.h>
#include <kernel/panic.h>
#include <shared/execbuf.h>
#include <shared/mem.h>

_Noreturn static void halt(struct process *proc) {
	kfree(proc->execbuf.buf);
	proc->execbuf.buf = NULL;
	process_switch_any();
}

static void try_fetch(struct process *proc, uint64_t *buf, size_t amt) {
	size_t bytes = amt * sizeof(uint64_t);
	if (proc->execbuf.pos + bytes > proc->execbuf.len)
		halt(proc);
	memcpy(buf, proc->execbuf.buf + proc->execbuf.pos, bytes);
	proc->execbuf.pos += bytes;
}

_Noreturn void execbuf_run(struct process *proc) {
	uint64_t buf[5];
	assert(proc == process_current); // idiotic, but needed because of _syscall.
	assert(proc->state == PS_RUNNING);
	assert(proc->execbuf.buf);

	for (;;) {
		try_fetch(proc, buf, 1);
		switch (buf[0]) {
			case EXECBUF_SYSCALL:
				try_fetch(proc, buf, 5);
				_syscall(buf[0], buf[1], buf[2], buf[3], buf[4]);
				break;
			case EXECBUF_JMP:
				try_fetch(proc, buf, 1);
				proc->regs.rcx = buf[0];
				break;
			default:
				halt(proc);
		}
	}
}