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61f42183fd
This allows jump-label entries to be cheaply updated on code which is not yet live. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Acked-by: Jason Baron <jbaron@redhat.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Jan Glauber <jang@linux.vnet.ibm.com>
71 lines
1.3 KiB
C
71 lines
1.3 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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struct jump_entry *entry;
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enum jump_label_type type;
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};
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static void __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 insn;
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int rc;
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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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rc = probe_kernel_write((void *)entry->code, &insn, JUMP_LABEL_NOP_SIZE);
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WARN_ON_ONCE(rc < 0);
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}
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static int __sm_arch_jump_label_transform(void *data)
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{
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struct insn_args *args = data;
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__jump_label_transform(args->entry, args->type);
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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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args.entry = entry;
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args.type = type;
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stop_machine(__sm_arch_jump_label_transform, &args, NULL);
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}
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void arch_jump_label_transform_static(struct jump_entry *entry,
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enum jump_label_type type)
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{
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__jump_label_transform(entry, type);
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}
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#endif
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