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 #include "entry.h" 22 23 /* empty control block to disable RI by loading it */ 24 struct runtime_instr_cb runtime_instr_empty_cb; 25 26 void runtime_instr_release(struct task_struct *tsk) 27 { 28 kfree(tsk->thread.ri_cb); 29 } 30 31 static void disable_runtime_instr(void) 32 { 33 struct task_struct *task = current; 34 struct pt_regs *regs; 35 36 if (!task->thread.ri_cb) 37 return; 38 regs = task_pt_regs(task); 39 preempt_disable(); 40 load_runtime_instr_cb(&runtime_instr_empty_cb); 41 kfree(task->thread.ri_cb); 42 task->thread.ri_cb = NULL; 43 preempt_enable(); 44 45 /* 46 * Make sure the RI bit is deleted from the PSW. If the user did not 47 * switch off RI before the system call the process will get a 48 * specification exception otherwise. 49 */ 50 regs->psw.mask &= ~PSW_MASK_RI; 51 } 52 53 static void init_runtime_instr_cb(struct runtime_instr_cb *cb) 54 { 55 cb->rla = 0xfff; 56 cb->s = 1; 57 cb->k = 1; 58 cb->ps = 1; 59 cb->pc = 1; 60 cb->key = PAGE_DEFAULT_KEY >> 4; 61 cb->v = 1; 62 } 63 64 /* 65 * The signum argument is unused. In older kernels it was used to 66 * specify a real-time signal. For backwards compatibility user space 67 * should pass a valid real-time signal number (the signum argument 68 * was checked in older kernels). 69 */ 70 SYSCALL_DEFINE2(s390_runtime_instr, int, command, int, signum) 71 { 72 struct runtime_instr_cb *cb; 73 74 if (!test_facility(64)) 75 return -EOPNOTSUPP; 76 77 if (command == S390_RUNTIME_INSTR_STOP) { 78 disable_runtime_instr(); 79 return 0; 80 } 81 82 if (command != S390_RUNTIME_INSTR_START) 83 return -EINVAL; 84 85 if (!current->thread.ri_cb) { 86 cb = kzalloc(sizeof(*cb), GFP_KERNEL); 87 if (!cb) 88 return -ENOMEM; 89 } else { 90 cb = current->thread.ri_cb; 91 memset(cb, 0, sizeof(*cb)); 92 } 93 94 init_runtime_instr_cb(cb); 95 96 /* now load the control block to make it available */ 97 preempt_disable(); 98 current->thread.ri_cb = cb; 99 load_runtime_instr_cb(cb); 100 preempt_enable(); 101 return 0; 102 } 103