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 } 95