5 files changed, 102 insertions, 1 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index cea0cd9a316f..afcd6632c94f 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -59,6 +59,7 @@ config X86
         select ANON_INODES
         select HAVE_ARCH_KMEMCHECK
         select HAVE_USER_RETURN_NOTIFIER
+        select HAVE_ARCH_JUMP_LABEL if !CC_OPTIMIZE_FOR_SIZE
 
 config INSTRUCTION_DECODER
         def_bool (KPROBES || PERF_EVENTS)
diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
new file mode 100644
index 000000000000..b4a2cb403370
--- /dev/null
+++ b/arch/x86/include/asm/jump_label.h
@@ -0,0 +1,47 @@
+#ifndef _ASM_X86_JUMP_LABEL_H
+#define _ASM_X86_JUMP_LABEL_H
+
+#ifdef __KERNEL__
+
+#include <linux/types.h>
+#include <asm/nops.h>
+
+#define JUMP_LABEL_NOP_SIZE 5
+
+# define JUMP_LABEL_INITIAL_NOP ".byte 0xe9 \n\t .long 0\n\t"
+
+# define JUMP_LABEL(key, label)                                 \
+        do {                                                    \
+                asm goto("1:"                                   \
+                        JUMP_LABEL_INITIAL_NOP                  \
+                        ".pushsection __jump_table,  \"a\" \n\t"\
+                        _ASM_PTR "1b, %l[" #label "], %c0 \n\t" \
+                        ".popsection \n\t"                      \
+                        : :  "i" (key) :  : label);             \
+        } while (0)
+
+#endif /* __KERNEL__ */
+
+#ifdef CONFIG_X86_64
+
+typedef u64 jump_label_t;
+
+struct jump_entry {
+        jump_label_t code;
+        jump_label_t target;
+        jump_label_t key;
+};
+
+#else
+
+typedef u32 jump_label_t;
+
+struct jump_entry {
+        jump_label_t code;
+        jump_label_t target;
+        jump_label_t key;
+};
+
+#endif
+
+#endif
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 0925676266bd..24fa1718ddb9 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -32,7 +32,7 @@ GCOV_PROFILE_paravirt.o		:= n
 obj-y                   := process_$(BITS).o signal.o entry_$(BITS).o
 obj-y                   += traps.o irq.o irq_$(BITS).o dumpstack_$(BITS).o
 obj-y                   += time.o ioport.o ldt.o dumpstack.o
-obj-y                   += setup.o x86_init.o i8259.o irqinit.o
+obj-y                   += setup.o x86_init.o i8259.o irqinit.o jump_label.o
 obj-$(CONFIG_X86_VISWS) += visws_quirks.o
 obj-$(CONFIG_X86_32)    += probe_roms_32.o
 obj-$(CONFIG_X86_32)    += sys_i386_32.o i386_ksyms_32.o
diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
new file mode 100644
index 000000000000..961b6b30ba90
--- /dev/null
+++ b/arch/x86/kernel/jump_label.c
@@ -0,0 +1,50 @@
+/*
+ * 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_nop5, 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_nop5, JUMP_LABEL_NOP_SIZE);
+}
+
+#endif
diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index e0bc186d7501..5399f58de7ed 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -239,6 +239,9 @@ int module_finalize(const Elf_Ehdr *hdr,
                 apply_paravirt(pseg, pseg + para->sh_size);
         }
 
+        /* make jump label nops */
+        jump_label_apply_nops(me);
+
         return module_bug_finalize(hdr, sechdrs, me);
 }