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| 2 | |
| 3 | * Copyright IBM Corp. 2012
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| 4 | * Author(s): Jan Glauber <[email protected]>
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| 5 |
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| 6 |
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| 7 | #include <linux/kernel.h>
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| 8 | #include <linux/syscalls.h>
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| 9 | #include <linux/signal.h>
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| 10 | #include <linux/mm.h>
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| 11 | #include <linux/slab.h>
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| 12 | #include <linux/init.h>
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| 13 | #include <linux/errno.h>
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| 14 | #include <linux/kernel_stat.h>
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| 15 | #include <linux/sched/task_stack.h>
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| 16 |
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| 17 | #include <asm/runtime_instr.h>
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| 18 | #include <asm/cpu_mf.h>
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| 19 | #include <asm/irq.h>
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| 20 |
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| 21 | #include "entry.h"
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| 22 |
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| 23 |
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| 24 | struct runtime_instr_cb runtime_instr_empty_cb;
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| 25 |
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| 26 | void runtime_instr_release(struct task_struct *tsk)
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| 27 | {
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| 28 | kfree(tsk->thread.ri_cb);
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| 29 | }
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| 30 |
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| 31 | static void disable_runtime_instr(void)
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| 32 | {
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| 33 | struct task_struct *task = current;
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| 34 | struct pt_regs *regs;
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| 35 |
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| 36 | if (!task->thread.ri_cb)
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| 37 | return;
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| 38 | regs = task_pt_regs(task);
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| 39 | preempt_disable();
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| 40 | load_runtime_instr_cb(&runtime_instr_empty_cb);
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| 41 | kfree(task->thread.ri_cb);
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| 42 | task->thread.ri_cb = NULL;
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| 43 | preempt_enable();
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| 44 |
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| 45 | |
| 46 | * Make sure the RI bit is deleted from the PSW. If the user did not
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| 47 | * switch off RI before the system call the process will get a
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| 48 | * specification exception otherwise.
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| 49 |
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| 50 | regs->psw.mask &= ~PSW_MASK_RI;
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| 51 | }
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| 52 |
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| 53 | static void init_runtime_instr_cb(struct runtime_instr_cb *cb)
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| 54 | {
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| 55 | cb->rla = 0xfff;
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| 56 | cb->s = 1;
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| 57 | cb->k = 1;
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| 58 | cb->ps = 1;
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| 59 | cb->pc = 1;
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| 60 | cb->key = PAGE_DEFAULT_KEY >> 4;
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| 61 | cb->v = 1;
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| 62 | }
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| 63 |
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| 64 | |
| 65 | * The signum argument is unused. In older kernels it was used to
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| 66 | * specify a real-time signal. For backwards compatibility user space
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| 67 | * should pass a valid real-time signal number (the signum argument
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| 68 | * was checked in older kernels).
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| 69 |
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| 70 | SYSCALL_DEFINE2(s390_runtime_instr, int, command, int, signum)
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| 71 | {
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| 72 | struct runtime_instr_cb *cb;
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| 73 |
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| 74 | if (!test_facility(64))
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| 75 | return -EOPNOTSUPP;
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| 76 |
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| 77 | if (command == S390_RUNTIME_INSTR_STOP) {
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| 78 | disable_runtime_instr();
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| 79 | return 0;
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| 80 | }
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| 81 |
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| 82 | if (command != S390_RUNTIME_INSTR_START)
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| 83 | return -EINVAL;
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| 84 |
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| 85 | if (!current->thread.ri_cb) {
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| 86 | cb = kzalloc_obj(*cb);
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| 87 | if (!cb)
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| 88 | return -ENOMEM;
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| 89 | } else {
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| 90 | cb = current->thread.ri_cb;
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| 91 | memset(cb, 0, sizeof(*cb));
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| 92 | }
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| 93 |
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| 94 | init_runtime_instr_cb(cb);
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| 95 |
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| 96 |
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| 97 | preempt_disable();
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| 98 | current->thread.ri_cb = cb;
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| 99 | load_runtime_instr_cb(cb);
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| 100 | preempt_enable();
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| 101 | return 0;
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| 102 | }
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