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 void runtime_instr_release(struct task_struct *tsk) 24 { 25 kfree(tsk->thread.ri_cb); 26 } 27 28 static void disable_runtime_instr(void) 29 { 30 struct task_struct *task = current; 31 struct pt_regs *regs; 32 33 if (!task->thread.ri_cb) 34 return; 35 regs = task_pt_regs(task); 36 preempt_disable(); 37 load_runtime_instr_cb(&runtime_instr_empty_cb); 38 kfree(task->thread.ri_cb); 39 task->thread.ri_cb = NULL; 40 preempt_enable(); 41 42 /* 43 * Make sure the RI bit is deleted from the PSW. If the user did not 44 * switch off RI before the system call the process will get a 45 * specification exception otherwise. 46 */ 47 regs->psw.mask &= ~PSW_MASK_RI; 48 } 49 50 static void init_runtime_instr_cb(struct runtime_instr_cb *cb) 51 { 52 cb->rla = 0xfff; 53 cb->s = 1; 54 cb->k = 1; 55 cb->ps = 1; 56 cb->pc = 1; 57 cb->key = PAGE_DEFAULT_KEY; 58 cb->v = 1; 59 } 60 61 SYSCALL_DEFINE1(s390_runtime_instr, int, command) 62 { 63 struct runtime_instr_cb *cb; 64 65 if (!test_facility(64)) 66 return -EOPNOTSUPP; 67 68 if (command == S390_RUNTIME_INSTR_STOP) { 69 disable_runtime_instr(); 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