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 void runtime_instr_release(struct task_struct *tsk) 25 { 26 kfree(tsk->thread.ri_cb); 27 } 28 29 static void disable_runtime_instr(void) 30 { 31 struct task_struct *task = current; 32 struct pt_regs *regs; 33 34 if (!task->thread.ri_cb) 35 return; 36 regs = task_pt_regs(task); 37 preempt_disable(); 38 load_runtime_instr_cb(&runtime_instr_empty_cb); 39 kfree(task->thread.ri_cb); 40 task->thread.ri_cb = NULL; 41 preempt_enable(); 42 43 /* 44 * Make sure the RI bit is deleted from the PSW. If the user did not 45 * switch off RI before the system call the process will get a 46 * specification exception otherwise. 47 */ 48 regs->psw.mask &= ~PSW_MASK_RI; 49 } 50 51 static void init_runtime_instr_cb(struct runtime_instr_cb *cb) 52 { 53 cb->rla = 0xfff; 54 cb->s = 1; 55 cb->k = 1; 56 cb->ps = 1; 57 cb->pc = 1; 58 cb->key = PAGE_DEFAULT_KEY; 59 cb->v = 1; 60 } 61 62 SYSCALL_DEFINE1(s390_runtime_instr, int, command) 63 { 64 struct runtime_instr_cb *cb; 65 66 if (!test_facility(64)) 67 return -EOPNOTSUPP; 68 69 if (command == S390_RUNTIME_INSTR_STOP) { 70 disable_runtime_instr(); 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 } 95