1/*
  2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
  3 *
  4 *   This program is free software; you can redistribute it and/or
  5 *   modify it under the terms of the GNU General Public License
  6 *   as published by the Free Software Foundation, version 2.
  7 *
  8 *   This program is distributed in the hope that it will be useful, but
  9 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 10 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 11 *   NON INFRINGEMENT.  See the GNU General Public License for
 12 *   more details.
 13 */
 14
 15#include <linux/percpu.h>
 16#include <linux/smp.h>
 17#include <linux/hardirq.h>
 18#include <linux/ptrace.h>
 19#include <asm/hv_driver.h>
 20#include <asm/irq_regs.h>
 21#include <asm/traps.h>
 22#include <hv/hypervisor.h>
 23#include <arch/interrupts.h>
 24
 25/* All messages are stored here */
 26static DEFINE_PER_CPU(HV_MsgState, msg_state);
 27
 28void init_messaging(void)
 29{
 30	/* Allocate storage for messages in kernel space */
 31	HV_MsgState *state = this_cpu_ptr(&msg_state);
 32	int rc = hv_register_message_state(state);
 33	if (rc != HV_OK)
 34		panic("hv_register_message_state: error %d", rc);
 35
 36	/* Make sure downcall interrupts will be enabled. */
 37	arch_local_irq_unmask(INT_INTCTRL_K);
 38}
 39
 40void hv_message_intr(struct pt_regs *regs, int intnum)
 41{
 42	/*
 43	 * We enter with interrupts disabled and leave them disabled,
 44	 * to match expectations of called functions (e.g.
 45	 * do_ccupdate_local() in mm/slab.c).  This is also consistent
 46	 * with normal call entry for device interrupts.
 47	 */
 48
 49	int message[HV_MAX_MESSAGE_SIZE/sizeof(int)];
 50	HV_RcvMsgInfo rmi;
 51	int nmsgs = 0;
 52
 53	/* Track time spent here in an interrupt context */
 54	struct pt_regs *old_regs = set_irq_regs(regs);
 55	irq_enter();
 56
 57#ifdef CONFIG_DEBUG_STACKOVERFLOW
 58	/* Debugging check for stack overflow: less than 1/8th stack free? */
 59	{
 60		long sp = stack_pointer - (long) current_thread_info();
 61		if (unlikely(sp < (sizeof(struct thread_info) + STACK_WARN))) {
 62			pr_emerg("%s: stack overflow: %ld\n",
 63				 __func__, sp - sizeof(struct thread_info));
 64			dump_stack();
 65		}
 66	}
 67#endif
 68
 69	while (1) {
 70		HV_MsgState *state = this_cpu_ptr(&msg_state);
 71		rmi = hv_receive_message(*state, (HV_VirtAddr) message,
 72					 sizeof(message));
 73		if (rmi.msglen == 0)
 74			break;
 75
 76		if (rmi.msglen < 0)
 77			panic("hv_receive_message failed: %d", rmi.msglen);
 78
 79		++nmsgs;
 80
 81		if (rmi.source == HV_MSG_TILE) {
 82			int tag;
 83
 84			/* we just send tags for now */
 85			BUG_ON(rmi.msglen != sizeof(int));
 86
 87			tag = message[0];
 88#ifdef CONFIG_SMP
 89			evaluate_message(message[0]);
 90#else
 91			panic("Received IPI message %d in UP mode", tag);
 92#endif
 93		} else if (rmi.source == HV_MSG_INTR) {
 94			HV_IntrMsg *him = (HV_IntrMsg *)message;
 95			struct hv_driver_cb *cb =
 96				(struct hv_driver_cb *)him->intarg;
 97			cb->callback(cb, him->intdata);
 98			__this_cpu_inc(irq_stat.irq_hv_msg_count);
 99		}
100	}
101
102	/*
103	 * We shouldn't have gotten a message downcall with no
104	 * messages available.
105	 */
106	if (nmsgs == 0)
107		panic("Message downcall invoked with no messages!");
108
109	/*
110	 * Track time spent against the current process again and
111	 * process any softirqs if they are waiting.
112	 */
113	irq_exit();
114	set_irq_regs(old_regs);
115}