arch/s390/kernel/runtime_instr.c

   1 /*
   2  * Copyright IBM Corp. 2012
   3  * Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
   4  */
   5
   6 #include <linux/kernel.h>
   7 #include <linux/syscalls.h>
   8 #include <linux/signal.h>
   9 #include <linux/mm.h>
  10 #include <linux/slab.h>
  11 #include <linux/init.h>
  12 #include <linux/errno.h>
  13 #include <linux/kernel_stat.h>
  14 #include <asm/runtime_instr.h>
  15 #include <asm/cpu_mf.h>
  16 #include <asm/irq.h>
  17
  18 /* empty control block to disable RI by loading it */
  19 struct runtime_instr_cb runtime_instr_empty_cb;
  20
  21 static int runtime_instr_avail(void)
  22 {
  23         return test_facility(64);
  24 }
  25
  26 static void disable_runtime_instr(void)
  27 {
  28         struct pt_regs *regs = task_pt_regs(current);
  29
  30         load_runtime_instr_cb(&runtime_instr_empty_cb);
  31
  32         /*
  33          * Make sure the RI bit is deleted from the PSW. If the user did not
  34          * switch off RI before the system call the process will get a
  35          * specification exception otherwise.
  36          */
  37         regs->psw.mask &= ~PSW_MASK_RI;
  38 }
  39
  40 static void init_runtime_instr_cb(struct runtime_instr_cb *cb)
  41 {
  42         cb->buf_limit = 0xfff;
  43         cb->int_requested = 1;
  44         cb->pstate = 1;
  45         cb->pstate_set_buf = 1;
  46         cb->pstate_sample = 1;
  47         cb->pstate_collect = 1;
  48         cb->key = PAGE_DEFAULT_KEY;
  49         cb->valid = 1;
  50 }
  51
  52 void exit_thread_runtime_instr(void)
  53 {
  54         struct task_struct *task = current;
  55
  56         if (!task->thread.ri_cb)
  57                 return;
  58         disable_runtime_instr();
  59         kfree(task->thread.ri_cb);
  60         task->thread.ri_signum = 0;
  61         task->thread.ri_cb = NULL;
  62 }
  63
  64 static void runtime_instr_int_handler(struct ext_code ext_code,
  65                                 unsigned int param32, unsigned long param64)
  66 {
  67         struct siginfo info;
  68
  69         if (!(param32 & CPU_MF_INT_RI_MASK))
  70                 return;
  71
  72         inc_irq_stat(IRQEXT_CMR);
  73
  74         if (!current->thread.ri_cb)
  75                 return;
  76         if (current->thread.ri_signum < SIGRTMIN ||
  77             current->thread.ri_signum > SIGRTMAX) {
  78                 WARN_ON_ONCE(1);
  79                 return;
  80         }
  81
  82         memset(&info, 0, sizeof(info));
  83         info.si_signo = current->thread.ri_signum;
  84         info.si_code = SI_QUEUE;
  85         if (param32 & CPU_MF_INT_RI_BUF_FULL)
  86                 info.si_int = ENOBUFS;
  87         else if (param32 & CPU_MF_INT_RI_HALTED)
  88                 info.si_int = ECANCELED;
  89         else
  90                 return; /* unknown reason */
  91
  92         send_sig_info(current->thread.ri_signum, &info, current);
  93 }
  94
  95 SYSCALL_DEFINE2(s390_runtime_instr, int, command, int, signum)
  96 {
  97         struct runtime_instr_cb *cb;
  98
  99         if (!runtime_instr_avail())
 100                 return -EOPNOTSUPP;
 101
 102         if (command == S390_RUNTIME_INSTR_STOP) {
 103                 preempt_disable();
 104                 exit_thread_runtime_instr();
 105                 preempt_enable();
 106                 return 0;
 107         }
 108
 109         if (command != S390_RUNTIME_INSTR_START ||
 110             (signum < SIGRTMIN || signum > SIGRTMAX))
 111                 return -EINVAL;
 112
 113         if (!current->thread.ri_cb) {
 114                 cb = kzalloc(sizeof(*cb), GFP_KERNEL);
 115                 if (!cb)
 116                         return -ENOMEM;
 117         } else {
 118                 cb = current->thread.ri_cb;
 119                 memset(cb, 0, sizeof(*cb));
 120         }
 121
 122         init_runtime_instr_cb(cb);
 123         current->thread.ri_signum = signum;
 124
 125         /* now load the control block to make it available */
 126         preempt_disable();
 127         current->thread.ri_cb = cb;
 128         load_runtime_instr_cb(cb);
 129         preempt_enable();
 130         return 0;
 131 }
 132
 133 static int __init runtime_instr_init(void)
 134 {
 135         int rc;
 136
 137         if (!runtime_instr_avail())
 138                 return 0;
 139
 140         irq_subclass_register(IRQ_SUBCLASS_MEASUREMENT_ALERT);
 141         rc = register_external_irq(EXT_IRQ_MEASURE_ALERT,
 142                                    runtime_instr_int_handler);
 143         if (rc)
 144                 irq_subclass_unregister(IRQ_SUBCLASS_MEASUREMENT_ALERT);
 145         else
 146                 pr_info("Runtime instrumentation facility initialized\n");
 147         return rc;
 148 }
 149 device_initcall(runtime_instr_init);