arch/s390/kernel/runtime_instr.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright IBM Corp. 2012
   4  * Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
   5  */
   6
   7 #include <linux/kernel.h>
   8 #include <linux/syscalls.h>
   9 #include <linux/signal.h>
  10 #include <linux/mm.h>
  11 #include <linux/slab.h>
  12 #include <linux/init.h>
  13 #include <linux/errno.h>
  14 #include <linux/kernel_stat.h>
  15 #include <linux/sched/task_stack.h>
  16
  17 #include <asm/runtime_instr.h>
  18 #include <asm/cpu_mf.h>
  19 #include <asm/irq.h>
  20
  21 /* empty control block to disable RI by loading it */
  22 struct runtime_instr_cb runtime_instr_empty_cb;
  23
  24 static void disable_runtime_instr(void)
  25 {
  26         struct pt_regs *regs = task_pt_regs(current);
  27
  28         load_runtime_instr_cb(&runtime_instr_empty_cb);
  29
  30         /*
  31          * Make sure the RI bit is deleted from the PSW. If the user did not
  32          * switch off RI before the system call the process will get a
  33          * specification exception otherwise.
  34          */
  35         regs->psw.mask &= ~PSW_MASK_RI;
  36 }
  37
  38 static void init_runtime_instr_cb(struct runtime_instr_cb *cb)
  39 {
  40         cb->buf_limit = 0xfff;
  41         cb->pstate = 1;
  42         cb->pstate_set_buf = 1;
  43         cb->pstate_sample = 1;
  44         cb->pstate_collect = 1;
  45         cb->key = PAGE_DEFAULT_KEY;
  46         cb->valid = 1;
  47 }
  48
  49 void exit_thread_runtime_instr(void)
  50 {
  51         struct task_struct *task = current;
  52
  53         if (!task->thread.ri_cb)
  54                 return;
  55         disable_runtime_instr();
  56         kfree(task->thread.ri_cb);
  57         task->thread.ri_cb = NULL;
  58 }
  59
  60 SYSCALL_DEFINE1(s390_runtime_instr, int, command)
  61 {
  62         struct runtime_instr_cb *cb;
  63
  64         if (!test_facility(64))
  65                 return -EOPNOTSUPP;
  66
  67         if (command == S390_RUNTIME_INSTR_STOP) {
  68                 preempt_disable();
  69                 exit_thread_runtime_instr();
  70                 preempt_enable();
  71                 return 0;
  72         }
  73
  74         if (command != S390_RUNTIME_INSTR_START)
  75                 return -EINVAL;
  76
  77         if (!current->thread.ri_cb) {
  78                 cb = kzalloc(sizeof(*cb), GFP_KERNEL);
  79                 if (!cb)
  80                         return -ENOMEM;
  81         } else {
  82                 cb = current->thread.ri_cb;
  83                 memset(cb, 0, sizeof(*cb));
  84         }
  85
  86         init_runtime_instr_cb(cb);
  87
  88         /* now load the control block to make it available */
  89         preempt_disable();
  90         current->thread.ri_cb = cb;
  91         load_runtime_instr_cb(cb);
  92         preempt_enable();
  93         return 0;
  94 }