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https://github.com/torvalds/linux
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9eaba29c79
The key member of the runtime instrumentation control block contains
only the access key, not the complete storage key. Therefore the value
must be shifted by four bits.
Note: this is only relevant for debugging purposes in case somebody
compiles a kernel with a default storage access key set to a value not
equal to zero.
Fixes: e4b8b3f33f ("s390: add support for runtime instrumentation")
Reported-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
103 lines
2.2 KiB
C
103 lines
2.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright IBM Corp. 2012
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* Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
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*/
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#include <linux/kernel.h>
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#include <linux/syscalls.h>
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#include <linux/signal.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/errno.h>
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#include <linux/kernel_stat.h>
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#include <linux/sched/task_stack.h>
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#include <asm/runtime_instr.h>
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#include <asm/cpu_mf.h>
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#include <asm/irq.h>
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#include "entry.h"
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/* empty control block to disable RI by loading it */
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struct runtime_instr_cb runtime_instr_empty_cb;
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void runtime_instr_release(struct task_struct *tsk)
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{
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kfree(tsk->thread.ri_cb);
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}
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static void disable_runtime_instr(void)
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{
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struct task_struct *task = current;
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struct pt_regs *regs;
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if (!task->thread.ri_cb)
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return;
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regs = task_pt_regs(task);
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preempt_disable();
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load_runtime_instr_cb(&runtime_instr_empty_cb);
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kfree(task->thread.ri_cb);
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task->thread.ri_cb = NULL;
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preempt_enable();
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/*
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* Make sure the RI bit is deleted from the PSW. If the user did not
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* switch off RI before the system call the process will get a
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* specification exception otherwise.
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*/
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regs->psw.mask &= ~PSW_MASK_RI;
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}
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static void init_runtime_instr_cb(struct runtime_instr_cb *cb)
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{
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cb->rla = 0xfff;
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cb->s = 1;
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cb->k = 1;
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cb->ps = 1;
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cb->pc = 1;
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cb->key = PAGE_DEFAULT_KEY >> 4;
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cb->v = 1;
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}
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/*
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* The signum argument is unused. In older kernels it was used to
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* specify a real-time signal. For backwards compatibility user space
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* should pass a valid real-time signal number (the signum argument
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* was checked in older kernels).
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*/
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SYSCALL_DEFINE2(s390_runtime_instr, int, command, int, signum)
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{
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struct runtime_instr_cb *cb;
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if (!test_facility(64))
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return -EOPNOTSUPP;
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if (command == S390_RUNTIME_INSTR_STOP) {
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disable_runtime_instr();
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return 0;
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}
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if (command != S390_RUNTIME_INSTR_START)
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return -EINVAL;
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if (!current->thread.ri_cb) {
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cb = kzalloc(sizeof(*cb), GFP_KERNEL);
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if (!cb)
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return -ENOMEM;
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} else {
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cb = current->thread.ri_cb;
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memset(cb, 0, sizeof(*cb));
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}
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init_runtime_instr_cb(cb);
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/* now load the control block to make it available */
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preempt_disable();
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current->thread.ri_cb = cb;
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load_runtime_instr_cb(cb);
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preempt_enable();
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return 0;
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}
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