Beispiel #1
0
/*
 * Runstate accounting
 */
static void get_runstate_snapshot(struct vcpu_runstate_info *res)
{
	u64 state_time;
	struct vcpu_runstate_info *state;

	BUG_ON(preemptible());

	state = &__get_cpu_var(runstate);

	/*
	 * The runstate info is always updated by the hypervisor on
	 * the current CPU, so there's no need to use anything
	 * stronger than a compiler barrier when fetching it.
	 */
	do {
		state_time = get64(&state->state_entry_time);
		barrier();
		*res = *state;
		barrier();
	} while (get64(&state->state_entry_time) != state_time);
}
/**
 * preempt_schedule_context - preempt_schedule called by tracing
 *
 * The tracing infrastructure uses preempt_enable_notrace to prevent
 * recursion and tracing preempt enabling caused by the tracing
 * infrastructure itself. But as tracing can happen in areas coming
 * from userspace or just about to enter userspace, a preempt enable
 * can occur before user_exit() is called. This will cause the scheduler
 * to be called when the system is still in usermode.
 *
 * To prevent this, the preempt_enable_notrace will use this function
 * instead of preempt_schedule() to exit user context if needed before
 * calling the scheduler.
 */
asmlinkage void __sched notrace preempt_schedule_context(void)
{
	enum ctx_state prev_ctx;

	if (likely(!preemptible()))
		return;

	/*
	 * Need to disable preemption in case user_exit() is traced
	 * and the tracer calls preempt_enable_notrace() causing
	 * an infinite recursion.
	 */
	preempt_disable_notrace();
	prev_ctx = exception_enter();
	preempt_enable_no_resched_notrace();

	preempt_schedule();

	preempt_disable_notrace();
	exception_exit(prev_ctx);
	preempt_enable_notrace();
}
struct multicall_space xen_mc_extend_args(unsigned long op, size_t size)
{
	struct mc_buffer *b = &__get_cpu_var(mc_buffer);
	struct multicall_space ret = { NULL, NULL };

	BUG_ON(preemptible());
	BUG_ON(b->argidx >= MC_ARGS);

	if (b->mcidx == 0)
		return ret;

	if (b->entries[b->mcidx - 1].op != op)
		return ret;

	if ((b->argidx + size) >= MC_ARGS)
		return ret;

	ret.mc = &b->entries[b->mcidx - 1];
	ret.args = &b->args[b->argidx];
	b->argidx += size;

	BUG_ON(b->argidx >= MC_ARGS);
	return ret;
}
Beispiel #4
0
struct multicall_space __xen_mc_entry(size_t args)
{
	struct mc_buffer *b = &__get_cpu_var(mc_buffer);
	struct multicall_space ret;
	unsigned argidx = roundup(b->argidx, sizeof(u64));

	BUG_ON(preemptible());
	BUG_ON(b->argidx > MC_ARGS);

	if (b->mcidx == MC_BATCH ||
	    (argidx + args) > MC_ARGS) {
		mc_stats_flush(b->mcidx == MC_BATCH ? FL_SLOTS : FL_ARGS);
		xen_mc_flush();
		argidx = roundup(b->argidx, sizeof(u64));
	}

	ret.mc = &b->entries[b->mcidx];
	b->mcidx++;
	ret.args = &b->args[argidx];
	b->argidx = argidx + args;

	BUG_ON(b->argidx > MC_ARGS);
	return ret;
}
void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
{
	struct stackframe frame;
	unsigned long irq_stack_ptr;
	int skip;

	pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);

	if (!tsk)
		tsk = current;

	if (!try_get_task_stack(tsk))
		return;

	/*
	 * Switching between stacks is valid when tracing current and in
	 * non-preemptible context.
	 */
	if (tsk == current && !preemptible())
		irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id());
	else
		irq_stack_ptr = 0;

	if (tsk == current) {
		frame.fp = (unsigned long)__builtin_frame_address(0);
		frame.sp = current_stack_pointer;
		frame.pc = (unsigned long)dump_backtrace;
	} else {
		/*
		 * task blocked in __switch_to
		 */
		frame.fp = thread_saved_fp(tsk);
		frame.sp = thread_saved_sp(tsk);
		frame.pc = thread_saved_pc(tsk);
	}
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	frame.graph = tsk->curr_ret_stack;
#endif

	skip = !!regs;
	printk("Call trace:\n");
	while (1) {
		unsigned long where = frame.pc;
		unsigned long stack;
		int ret;

		/* skip until specified stack frame */
		if (!skip) {
			dump_backtrace_entry(where);
		} else if (frame.fp == regs->regs[29]) {
			skip = 0;
			/*
			 * Mostly, this is the case where this function is
			 * called in panic/abort. As exception handler's
			 * stack frame does not contain the corresponding pc
			 * at which an exception has taken place, use regs->pc
			 * instead.
			 */
			dump_backtrace_entry(regs->pc);
		}
		ret = unwind_frame(tsk, &frame);
		if (ret < 0)
			break;
		stack = frame.sp;
		if (in_exception_text(where)) {
			/*
			 * If we switched to the irq_stack before calling this
			 * exception handler, then the pt_regs will be on the
			 * task stack. The easiest way to tell is if the large
			 * pt_regs would overlap with the end of the irq_stack.
			 */
			if (stack < irq_stack_ptr &&
			    (stack + sizeof(struct pt_regs)) > irq_stack_ptr)
				stack = IRQ_STACK_TO_TASK_STACK(irq_stack_ptr);

			dump_mem("", "Exception stack", stack,
				 stack + sizeof(struct pt_regs));
		}
	}

	put_task_stack(tsk);
}
Beispiel #6
0
/**
 * kvm_arm_get_running_vcpu - get the vcpu running on the current CPU.
 * Must be called from non-preemptible context
 */
struct kvm_vcpu *kvm_arm_get_running_vcpu(void)
{
	BUG_ON(preemptible());
	return __this_cpu_read(kvm_arm_running_vcpu);
}
Beispiel #7
0
static void kvm_arm_set_running_vcpu(struct kvm_vcpu *vcpu)
{
	BUG_ON(preemptible());
	__this_cpu_write(kvm_arm_running_vcpu, vcpu);
}
void xen_setup_cpu_clockevents(void)
{
	BUG_ON(preemptible());

	clockevents_register_device(&__get_cpu_var(xen_clock_events));
}
Beispiel #9
0
void xen_mc_flush(void)
{
	struct mc_buffer *b = &__get_cpu_var(mc_buffer);
	struct multicall_entry *mc;
	int ret = 0;
	unsigned long flags;
	int i;

	BUG_ON(preemptible());

	/* Disable interrupts in case someone comes in and queues
	   something in the middle */
	local_irq_save(flags);

	trace_xen_mc_flush(b->mcidx, b->argidx, b->cbidx);

	switch (b->mcidx) {
	case 0:
		/* no-op */
		BUG_ON(b->argidx != 0);
		break;

	case 1:
		/* Singleton multicall - bypass multicall machinery
		   and just do the call directly. */
		mc = &b->entries[0];

		mc->result = privcmd_call(mc->op,
					  mc->args[0], mc->args[1], mc->args[2], 
					  mc->args[3], mc->args[4]);
		ret = mc->result < 0;
		break;

	default:
#if MC_DEBUG
		memcpy(b->debug, b->entries,
		       b->mcidx * sizeof(struct multicall_entry));
#endif

		if (HYPERVISOR_multicall(b->entries, b->mcidx) != 0)
			BUG();
		for (i = 0; i < b->mcidx; i++)
			if (b->entries[i].result < 0)
				ret++;

#if MC_DEBUG
		if (ret) {
			printk(KERN_ERR "%d multicall(s) failed: cpu %d\n",
			       ret, smp_processor_id());
			dump_stack();
			for (i = 0; i < b->mcidx; i++) {
				printk(KERN_DEBUG "  call %2d/%d: op=%lu arg=[%lx] result=%ld\t%pF\n",
				       i+1, b->mcidx,
				       b->debug[i].op,
				       b->debug[i].args[0],
				       b->entries[i].result,
				       b->caller[i]);
			}
		}
#endif
	}

	b->mcidx = 0;
	b->argidx = 0;

	for (i = 0; i < b->cbidx; i++) {
		struct callback *cb = &b->callbacks[i];

		(*cb->fn)(cb->data);
	}
	b->cbidx = 0;

	local_irq_restore(flags);

	WARN_ON(ret);
}
Beispiel #10
0
/*
 * AArch64 PCS assigns the frame pointer to x29.
 *
 * A simple function prologue looks like this:
 * 	sub	sp, sp, #0x10
 *   	stp	x29, x30, [sp]
 *	mov	x29, sp
 *
 * A simple function epilogue looks like this:
 *	mov	sp, x29
 *	ldp	x29, x30, [sp]
 *	add	sp, sp, #0x10
 */
int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)
{
	unsigned long high, low;
	unsigned long fp = frame->fp;
	unsigned long irq_stack_ptr;

	/*
	 * Switching between stacks is valid when tracing current and in
	 * non-preemptible context.
	 */
	if (tsk == current && !preemptible())
		irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id());
	else
		irq_stack_ptr = 0;

	low  = frame->sp;
	/* irq stacks are not THREAD_SIZE aligned */
	if (on_irq_stack(frame->sp, raw_smp_processor_id()))
		high = irq_stack_ptr;
	else
		high = ALIGN(low, THREAD_SIZE) - 0x20;

	if (fp < low || fp > high || fp & 0xf)
		return -EINVAL;

	frame->sp = fp + 0x10;
	frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp));
	frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8));

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	if (tsk && tsk->ret_stack &&
			(frame->pc == (unsigned long)return_to_handler)) {
		/*
		 * This is a case where function graph tracer has
		 * modified a return address (LR) in a stack frame
		 * to hook a function return.
		 * So replace it to an original value.
		 */
		frame->pc = tsk->ret_stack[frame->graph--].ret;
	}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

	/*
	 * Check whether we are going to walk through from interrupt stack
	 * to task stack.
	 * If we reach the end of the stack - and its an interrupt stack,
	 * unpack the dummy frame to find the original elr.
	 *
	 * Check the frame->fp we read from the bottom of the irq_stack,
	 * and the original task stack pointer are both in current->stack.
	 */
	if (frame->sp == irq_stack_ptr) {
		struct pt_regs *irq_args;
		unsigned long orig_sp = IRQ_STACK_TO_TASK_STACK(irq_stack_ptr);

		if (object_starts_on_stack((void *)orig_sp) &&
		   object_starts_on_stack((void *)frame->fp)) {
			frame->sp = orig_sp;

			/* orig_sp is the saved pt_regs, find the elr */
			irq_args = (struct pt_regs *)orig_sp;
			frame->pc = irq_args->pc;
		} else {
			/*
			 * This frame has a non-standard format, and we
			 * didn't fix it, because the data looked wrong.
			 * Refuse to output this frame.
			 */
			return -EINVAL;
		}
	}

	return 0;
}