linux/arch/x86/kernel/jump_label.c
H. Peter Anvin dc326fca2b x86, cpu: Clean up and unify the NOP selection infrastructure
Clean up and unify the NOP selection infrastructure:

- Make the atomic 5-byte NOP a part of the selection system.
- Pick NOPs once during early boot and then be done with it.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jason Baron <jbaron@redhat.com>
Link: http://lkml.kernel.org/r/1303166160-10315-3-git-send-email-hpa@linux.intel.com
2011-04-18 16:40:21 -07:00

51 lines
1.1 KiB
C

/*
* jump label x86 support
*
* Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
*
*/
#include <linux/jump_label.h>
#include <linux/memory.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/jhash.h>
#include <linux/cpu.h>
#include <asm/kprobes.h>
#include <asm/alternative.h>
#ifdef HAVE_JUMP_LABEL
union jump_code_union {
char code[JUMP_LABEL_NOP_SIZE];
struct {
char jump;
int offset;
} __attribute__((packed));
};
void arch_jump_label_transform(struct jump_entry *entry,
enum jump_label_type type)
{
union jump_code_union code;
if (type == JUMP_LABEL_ENABLE) {
code.jump = 0xe9;
code.offset = entry->target -
(entry->code + JUMP_LABEL_NOP_SIZE);
} else
memcpy(&code, ideal_nops[NOP_ATOMIC5], JUMP_LABEL_NOP_SIZE);
get_online_cpus();
mutex_lock(&text_mutex);
text_poke_smp((void *)entry->code, &code, JUMP_LABEL_NOP_SIZE);
mutex_unlock(&text_mutex);
put_online_cpus();
}
void arch_jump_label_text_poke_early(jump_label_t addr)
{
text_poke_early((void *)addr, ideal_nops[NOP_ATOMIC5],
JUMP_LABEL_NOP_SIZE);
}
#endif