Commit 5373db88 authored by Jan Glauber's avatar Jan Glauber Committed by Steven Rostedt

jump label: Add s390 support

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: default avatarJan Glauber <jang@linux.vnet.ibm.com>
LKML-Reference: <6935d2c41ce111e1719176ed4bbd3dbe4de80855.1300299760.git.jbaron@redhat.com>
Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent ef647894
......@@ -88,6 +88,7 @@ config S390
select HAVE_KERNEL_XZ
select HAVE_GET_USER_PAGES_FAST
select HAVE_ARCH_MUTEX_CPU_RELAX
select HAVE_ARCH_JUMP_LABEL if !MARCH_G5
select ARCH_INLINE_SPIN_TRYLOCK
select ARCH_INLINE_SPIN_TRYLOCK_BH
select ARCH_INLINE_SPIN_LOCK
......
#ifndef _ASM_S390_JUMP_LABEL_H
#define _ASM_S390_JUMP_LABEL_H
#include <linux/types.h>
#define JUMP_LABEL_NOP_SIZE 6
#ifdef CONFIG_64BIT
#define ASM_PTR ".quad"
#define ASM_ALIGN ".balign 8"
#else
#define ASM_PTR ".long"
#define ASM_ALIGN ".balign 4"
#endif
static __always_inline bool arch_static_branch(struct jump_label_key *key)
{
asm goto("0: brcl 0,0\n"
".pushsection __jump_table, \"aw\"\n"
ASM_ALIGN "\n"
ASM_PTR " 0b, %l[label], %0\n"
".popsection\n"
: : "X" (key) : : label);
return false;
label:
return true;
}
typedef unsigned long jump_label_t;
struct jump_entry {
jump_label_t code;
jump_label_t target;
jump_label_t key;
};
#endif
......@@ -23,7 +23,7 @@ CFLAGS_sysinfo.o += -Iinclude/math-emu -Iarch/s390/math-emu -w
obj-y := bitmap.o traps.o time.o process.o base.o early.o setup.o \
processor.o sys_s390.o ptrace.o signal.o cpcmd.o ebcdic.o \
s390_ext.o debug.o irq.o ipl.o dis.o diag.o mem_detect.o \
vdso.o vtime.o sysinfo.o nmi.o sclp.o
vdso.o vtime.o sysinfo.o nmi.o sclp.o jump_label.o
obj-y += $(if $(CONFIG_64BIT),entry64.o,entry.o)
obj-y += $(if $(CONFIG_64BIT),reipl64.o,reipl.o)
......
/*
* 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
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