arch/tile/kernel/messaging.c

   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 */
  26 static DEFINE_PER_CPU(HV_MsgState, msg_state);
  27
  28 void 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
  40 void 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 }