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jump label: Add s390 support

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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>
This commit is contained in:
Jan Glauber
2011-03-16 15:58:30 -04:00
committed by Steven Rostedt
parent ef64789413
commit 5373db886b
4 changed files with 98 additions and 1 deletions
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59
arch/s390/kernel/jump_label.c Normal file
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/*
* Jump label s390 support
*
* Copyright IBM Corp. 2011
* Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
*/
#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/stop_machine.h>
#include <linux/jump_label.h>
#include <asm/ipl.h>
#ifdef HAVE_JUMP_LABEL
struct insn {
u16 opcode;
s32 offset;
} __packed;
struct insn_args {
unsigned long *target;
struct insn *insn;
ssize_t size;
};
static int __arch_jump_label_transform(void *data)
{
struct insn_args *args = data;
int rc;
rc = probe_kernel_write(args->target, args->insn, args->size);
WARN_ON_ONCE(rc < 0);
return 0;
}
void arch_jump_label_transform(struct jump_entry *entry,
enum jump_label_type type)
{
struct insn_args args;
struct insn insn;
if (type == JUMP_LABEL_ENABLE) {
/* brcl 15,offset */
insn.opcode = 0xc0f4;
insn.offset = (entry->target - entry->code) >> 1;
} else {
/* brcl 0,0 */
insn.opcode = 0xc004;
insn.offset = 0;
}
args.target = (void *) entry->code;
args.insn = &insn;
args.size = JUMP_LABEL_NOP_SIZE;
stop_machine(__arch_jump_label_transform, &args, NULL);
}
#endif