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