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}
116