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5373db886b
Implement the architecture backend for jump label support on s390. For a shared kernel booted from a NSS silently disable jump labels because the NSS is read-only. Therefore jump labels will be disabled in a shared kernel and can't be activated. Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com> LKML-Reference: <6935d2c41ce111e1719176ed4bbd3dbe4de80855.1300299760.git.jbaron@redhat.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
60 lines
1.1 KiB
C
60 lines
1.1 KiB
C
/*
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* Jump label s390 support
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*
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* Copyright IBM Corp. 2011
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* Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
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*/
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#include <linux/module.h>
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#include <linux/uaccess.h>
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#include <linux/stop_machine.h>
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#include <linux/jump_label.h>
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#include <asm/ipl.h>
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#ifdef HAVE_JUMP_LABEL
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struct insn {
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u16 opcode;
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s32 offset;
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} __packed;
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struct insn_args {
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unsigned long *target;
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struct insn *insn;
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ssize_t size;
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};
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static int __arch_jump_label_transform(void *data)
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{
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struct insn_args *args = data;
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int rc;
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rc = probe_kernel_write(args->target, args->insn, args->size);
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WARN_ON_ONCE(rc < 0);
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return 0;
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}
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void arch_jump_label_transform(struct jump_entry *entry,
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enum jump_label_type type)
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{
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struct insn_args args;
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struct insn insn;
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if (type == JUMP_LABEL_ENABLE) {
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/* brcl 15,offset */
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insn.opcode = 0xc0f4;
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insn.offset = (entry->target - entry->code) >> 1;
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} else {
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/* brcl 0,0 */
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insn.opcode = 0xc004;
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insn.offset = 0;
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}
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args.target = (void *) entry->code;
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args.insn = &insn;
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args.size = JUMP_LABEL_NOP_SIZE;
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stop_machine(__arch_jump_label_transform, &args, NULL);
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}
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#endif
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