12 files changed, 442 insertions, 4 deletions

diff --git a/Makefile b/Makefile
index 92ab33f16cf0..a906378d505d 100644
--- a/Makefile
+++ b/Makefile
@@ -591,6 +591,11 @@ KBUILD_CFLAGS	+= $(call cc-option,-fno-strict-overflow)
 # conserve stack if available
 KBUILD_CFLAGS   += $(call cc-option,-fconserve-stack)
 
+# check for 'asm goto'
+ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC)), y)
+        KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
+endif
+
 # Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments
 # But warn user when we do so
 warn-assign = \
diff --git a/arch/Kconfig b/arch/Kconfig
index 4877a8c8ee16..1462d8492d89 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -158,4 +158,7 @@ config HAVE_PERF_EVENTS_NMI
           subsystem.  Also has support for calculating CPU cycle events
           to determine how many clock cycles in a given period.
 
+config HAVE_ARCH_JUMP_LABEL
+        bool
+
 source "kernel/gcov/Kconfig"
diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index 634bf782dca5..76561d20ea2f 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -4,6 +4,7 @@
 #include <linux/types.h>
 #include <linux/stddef.h>
 #include <linux/stringify.h>
+#include <linux/jump_label.h>
 #include <asm/asm.h>
 
 /*
@@ -182,7 +183,7 @@ extern void *text_poke_early(void *addr, const void *opcode, size_t len);
 extern void *text_poke(void *addr, const void *opcode, size_t len);
 extern void *text_poke_smp(void *addr, const void *opcode, size_t len);
 
-#if defined(CONFIG_DYNAMIC_FTRACE)
+#if defined(CONFIG_DYNAMIC_FTRACE) || defined(HAVE_JUMP_LABEL)
 #define IDEAL_NOP_SIZE_5 5
 extern unsigned char ideal_nop5[IDEAL_NOP_SIZE_5];
 extern void arch_init_ideal_nop5(void);
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 083bd010d92c..cb0e6d385f6d 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -641,7 +641,7 @@ void *__kprobes text_poke_smp(void *addr, const void *opcode, size_t len)
         return addr;
 }
 
-#if defined(CONFIG_DYNAMIC_FTRACE)
+#if defined(CONFIG_DYNAMIC_FTRACE) || defined(HAVE_JUMP_LABEL)
 
 unsigned char ideal_nop5[IDEAL_NOP_SIZE_5];
 
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 8a92a170fb7d..ef2af9948eac 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -220,6 +220,8 @@
                                                                         \
         BUG_TABLE                                                       \
                                                                         \
+        JUMP_TABLE                                                      \
+                                                                        \
         /* PCI quirks */                                                \
         .pci_fixup        : AT(ADDR(.pci_fixup) - LOAD_OFFSET) {        \
                 VMLINUX_SYMBOL(__start_pci_fixups_early) = .;           \
@@ -563,6 +565,14 @@
 #define BUG_TABLE
 #endif
 
+#define JUMP_TABLE                                                      \
+        . = ALIGN(8);                                                   \
+        __jump_table : AT(ADDR(__jump_table) - LOAD_OFFSET) {           \
+                VMLINUX_SYMBOL(__start___jump_table) = .;               \
+                *(__jump_table)                                         \
+                VMLINUX_SYMBOL(__stop___jump_table) = .;                \
+        }
+
 #ifdef CONFIG_PM_TRACE
 #define TRACEDATA                                                       \
         . = ALIGN(4);                                                   \
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
new file mode 100644
index 000000000000..de58656d28e0
--- /dev/null
+++ b/include/linux/jump_label.h
@@ -0,0 +1,58 @@
+#ifndef _LINUX_JUMP_LABEL_H
+#define _LINUX_JUMP_LABEL_H
+
+#if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_HAVE_ARCH_JUMP_LABEL)
+# include <asm/jump_label.h>
+# define HAVE_JUMP_LABEL
+#endif
+
+enum jump_label_type {
+        JUMP_LABEL_ENABLE,
+        JUMP_LABEL_DISABLE
+};
+
+struct module;
+
+#ifdef HAVE_JUMP_LABEL
+
+extern struct jump_entry __start___jump_table[];
+extern struct jump_entry __stop___jump_table[];
+
+extern void arch_jump_label_transform(struct jump_entry *entry,
+                                 enum jump_label_type type);
+extern void jump_label_update(unsigned long key, enum jump_label_type type);
+extern void jump_label_apply_nops(struct module *mod);
+extern void arch_jump_label_text_poke_early(jump_label_t addr);
+
+#define enable_jump_label(key) \
+        jump_label_update((unsigned long)key, JUMP_LABEL_ENABLE);
+
+#define disable_jump_label(key) \
+        jump_label_update((unsigned long)key, JUMP_LABEL_DISABLE);
+
+#else
+
+#define JUMP_LABEL(key, label)                  \
+do {                                            \
+        if (unlikely(*key))                     \
+                goto label;                     \
+} while (0)
+
+#define enable_jump_label(cond_var)     \
+do {                                    \
+       *(cond_var) = 1;                 \
+} while (0)
+
+#define disable_jump_label(cond_var)    \
+do {                                    \
+       *(cond_var) = 0;                 \
+} while (0)
+
+static inline int jump_label_apply_nops(struct module *mod)
+{
+        return 0;
+}
+
+#endif
+
+#endif
diff --git a/include/linux/module.h b/include/linux/module.h
index 8a6b9fdc7ffa..403ac26023ce 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -350,7 +350,10 @@ struct module
         struct tracepoint *tracepoints;
         unsigned int num_tracepoints;
 #endif
-
+#ifdef HAVE_JUMP_LABEL
+        struct jump_entry *jump_entries;
+        unsigned int num_jump_entries;
+#endif
 #ifdef CONFIG_TRACING
         const char **trace_bprintk_fmt_start;
         unsigned int num_trace_bprintk_fmt;
diff --git a/kernel/Makefile b/kernel/Makefile
index 0b72d1a74be0..d52b473c99a1 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -10,7 +10,7 @@ obj-y     = sched.o fork.o exec_domain.o panic.o printk.o \
             kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \
             hrtimer.o rwsem.o nsproxy.o srcu.o semaphore.o \
             notifier.o ksysfs.o pm_qos_params.o sched_clock.o cred.o \
-            async.o range.o
+            async.o range.o jump_label.o
 obj-$(CONFIG_HAVE_EARLY_RES) += early_res.o
 obj-y += groups.o
 
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
new file mode 100644
index 000000000000..460fd40112b3
--- /dev/null
+++ b/kernel/jump_label.c
@@ -0,0 +1,346 @@
+/*
+ * jump label 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/slab.h>
+#include <linux/sort.h>
+#include <linux/err.h>
+
+#ifdef HAVE_JUMP_LABEL
+
+#define JUMP_LABEL_HASH_BITS 6
+#define JUMP_LABEL_TABLE_SIZE (1 << JUMP_LABEL_HASH_BITS)
+static struct hlist_head jump_label_table[JUMP_LABEL_TABLE_SIZE];
+
+/* mutex to protect coming/going of the the jump_label table */
+static DEFINE_MUTEX(jump_label_mutex);
+
+struct jump_label_entry {
+        struct hlist_node hlist;
+        struct jump_entry *table;
+        int nr_entries;
+        /* hang modules off here */
+        struct hlist_head modules;
+        unsigned long key;
+};
+
+struct jump_label_module_entry {
+        struct hlist_node hlist;
+        struct jump_entry *table;
+        int nr_entries;
+        struct module *mod;
+};
+
+static int jump_label_cmp(const void *a, const void *b)
+{
+        const struct jump_entry *jea = a;
+        const struct jump_entry *jeb = b;
+
+        if (jea->key < jeb->key)
+                return -1;
+
+        if (jea->key > jeb->key)
+                return 1;
+
+        return 0;
+}
+
+static void
+sort_jump_label_entries(struct jump_entry *start, struct jump_entry *stop)
+{
+        unsigned long size;
+
+        size = (((unsigned long)stop - (unsigned long)start)
+                                        / sizeof(struct jump_entry));
+        sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
+}
+
+static struct jump_label_entry *get_jump_label_entry(jump_label_t key)
+{
+        struct hlist_head *head;
+        struct hlist_node *node;
+        struct jump_label_entry *e;
+        u32 hash = jhash((void *)&key, sizeof(jump_label_t), 0);
+
+        head = &jump_label_table[hash & (JUMP_LABEL_TABLE_SIZE - 1)];
+        hlist_for_each_entry(e, node, head, hlist) {
+                if (key == e->key)
+                        return e;
+        }
+        return NULL;
+}
+
+static struct jump_label_entry *
+add_jump_label_entry(jump_label_t key, int nr_entries, struct jump_entry *table)
+{
+        struct hlist_head *head;
+        struct jump_label_entry *e;
+        u32 hash;
+
+        e = get_jump_label_entry(key);
+        if (e)
+                return ERR_PTR(-EEXIST);
+
+        e = kmalloc(sizeof(struct jump_label_entry), GFP_KERNEL);
+        if (!e)
+                return ERR_PTR(-ENOMEM);
+
+        hash = jhash((void *)&key, sizeof(jump_label_t), 0);
+        head = &jump_label_table[hash & (JUMP_LABEL_TABLE_SIZE - 1)];
+        e->key = key;
+        e->table = table;
+        e->nr_entries = nr_entries;
+        INIT_HLIST_HEAD(&(e->modules));
+        hlist_add_head(&e->hlist, head);
+        return e;
+}
+
+static int
+build_jump_label_hashtable(struct jump_entry *start, struct jump_entry *stop)
+{
+        struct jump_entry *iter, *iter_begin;
+        struct jump_label_entry *entry;
+        int count;
+
+        sort_jump_label_entries(start, stop);
+        iter = start;
+        while (iter < stop) {
+                entry = get_jump_label_entry(iter->key);
+                if (!entry) {
+                        iter_begin = iter;
+                        count = 0;
+                        while ((iter < stop) &&
+                                (iter->key == iter_begin->key)) {
+                                iter++;
+                                count++;
+                        }
+                        entry = add_jump_label_entry(iter_begin->key,
+                                                        count, iter_begin);
+                        if (IS_ERR(entry))
+                                return PTR_ERR(entry);
+                 } else {
+                        WARN_ONCE(1, KERN_ERR "build_jump_hashtable: unexpected entry!\n");
+                        return -1;
+                }
+        }
+        return 0;
+}
+
+/***
+ * jump_label_update - update jump label text
+ * @key -  key value associated with a a jump label
+ * @type - enum set to JUMP_LABEL_ENABLE or JUMP_LABEL_DISABLE
+ *
+ * Will enable/disable the jump for jump label @key, depending on the
+ * value of @type.
+ *
+ */
+
+void jump_label_update(unsigned long key, enum jump_label_type type)
+{
+        struct jump_entry *iter;
+        struct jump_label_entry *entry;
+        struct hlist_node *module_node;
+        struct jump_label_module_entry *e_module;
+        int count;
+
+        mutex_lock(&jump_label_mutex);
+        entry = get_jump_label_entry((jump_label_t)key);
+        if (entry) {
+                count = entry->nr_entries;
+                iter = entry->table;
+                while (count--) {
+                        if (kernel_text_address(iter->code))
+                                arch_jump_label_transform(iter, type);
+                        iter++;
+                }
+                /* eanble/disable jump labels in modules */
+                hlist_for_each_entry(e_module, module_node, &(entry->modules),
+                                                        hlist) {
+                        count = e_module->nr_entries;
+                        iter = e_module->table;
+                        while (count--) {
+                                if (kernel_text_address(iter->code))
+                                        arch_jump_label_transform(iter, type);
+                                iter++;
+                        }
+                }
+        }
+        mutex_unlock(&jump_label_mutex);
+}
+
+static __init int init_jump_label(void)
+{
+        int ret;
+        struct jump_entry *iter_start = __start___jump_table;
+        struct jump_entry *iter_stop = __stop___jump_table;
+        struct jump_entry *iter;
+
+        mutex_lock(&jump_label_mutex);
+        ret = build_jump_label_hashtable(__start___jump_table,
+                                         __stop___jump_table);
+        iter = iter_start;
+        while (iter < iter_stop) {
+                arch_jump_label_text_poke_early(iter->code);
+                iter++;
+        }
+        mutex_unlock(&jump_label_mutex);
+        return ret;
+}
+early_initcall(init_jump_label);
+
+#ifdef CONFIG_MODULES
+
+static struct jump_label_module_entry *
+add_jump_label_module_entry(struct jump_label_entry *entry,
+                            struct jump_entry *iter_begin,
+                            int count, struct module *mod)
+{
+        struct jump_label_module_entry *e;
+
+        e = kmalloc(sizeof(struct jump_label_module_entry), GFP_KERNEL);
+        if (!e)
+                return ERR_PTR(-ENOMEM);
+        e->mod = mod;
+        e->nr_entries = count;
+        e->table = iter_begin;
+        hlist_add_head(&e->hlist, &entry->modules);
+        return e;
+}
+
+static int add_jump_label_module(struct module *mod)
+{
+        struct jump_entry *iter, *iter_begin;
+        struct jump_label_entry *entry;
+        struct jump_label_module_entry *module_entry;
+        int count;
+
+        /* if the module doesn't have jump label entries, just return */
+        if (!mod->num_jump_entries)
+                return 0;
+
+        sort_jump_label_entries(mod->jump_entries,
+                                mod->jump_entries + mod->num_jump_entries);
+        iter = mod->jump_entries;
+        while (iter < mod->jump_entries + mod->num_jump_entries) {
+                entry = get_jump_label_entry(iter->key);
+                iter_begin = iter;
+                count = 0;
+                while ((iter < mod->jump_entries + mod->num_jump_entries) &&
+                        (iter->key == iter_begin->key)) {
+                                iter++;
+                                count++;
+                }
+                if (!entry) {
+                        entry = add_jump_label_entry(iter_begin->key, 0, NULL);
+                        if (IS_ERR(entry))
+                                return PTR_ERR(entry);
+                }
+                module_entry = add_jump_label_module_entry(entry, iter_begin,
+                                                           count, mod);
+                if (IS_ERR(module_entry))
+                        return PTR_ERR(module_entry);
+        }
+        return 0;
+}
+
+static void remove_jump_label_module(struct module *mod)
+{
+        struct hlist_head *head;
+        struct hlist_node *node, *node_next, *module_node, *module_node_next;
+        struct jump_label_entry *e;
+        struct jump_label_module_entry *e_module;
+        int i;
+
+        /* if the module doesn't have jump label entries, just return */
+        if (!mod->num_jump_entries)
+                return;
+
+        for (i = 0; i < JUMP_LABEL_TABLE_SIZE; i++) {
+                head = &jump_label_table[i];
+                hlist_for_each_entry_safe(e, node, node_next, head, hlist) {
+                        hlist_for_each_entry_safe(e_module, module_node,
+                                                  module_node_next,
+                                                  &(e->modules), hlist) {
+                                if (e_module->mod == mod) {
+                                        hlist_del(&e_module->hlist);
+                                        kfree(e_module);
+                                }
+                        }
+                        if (hlist_empty(&e->modules) && (e->nr_entries == 0)) {
+                                hlist_del(&e->hlist);
+                                kfree(e);
+                        }
+                }
+        }
+}
+
+static int
+jump_label_module_notify(struct notifier_block *self, unsigned long val,
+                         void *data)
+{
+        struct module *mod = data;
+        int ret = 0;
+
+        switch (val) {
+        case MODULE_STATE_COMING:
+                mutex_lock(&jump_label_mutex);
+                ret = add_jump_label_module(mod);
+                if (ret)
+                        remove_jump_label_module(mod);
+                mutex_unlock(&jump_label_mutex);
+                break;
+        case MODULE_STATE_GOING:
+                mutex_lock(&jump_label_mutex);
+                remove_jump_label_module(mod);
+                mutex_unlock(&jump_label_mutex);
+                break;
+        }
+        return ret;
+}
+
+/***
+ * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
+ * @mod: module to patch
+ *
+ * Allow for run-time selection of the optimal nops. Before the module
+ * loads patch these with arch_get_jump_label_nop(), which is specified by
+ * the arch specific jump label code.
+ */
+void jump_label_apply_nops(struct module *mod)
+{
+        struct jump_entry *iter;
+
+        /* if the module doesn't have jump label entries, just return */
+        if (!mod->num_jump_entries)
+                return;
+
+        iter = mod->jump_entries;
+        while (iter < mod->jump_entries + mod->num_jump_entries) {
+                arch_jump_label_text_poke_early(iter->code);
+                iter++;
+        }
+}
+
+struct notifier_block jump_label_module_nb = {
+        .notifier_call = jump_label_module_notify,
+        .priority = 0,
+};
+
+static __init int init_jump_label_module(void)
+{
+        return register_module_notifier(&jump_label_module_nb);
+}
+early_initcall(init_jump_label_module);
+
+#endif /* CONFIG_MODULES */
+
+#endif
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 6dd5359e1f0e..18904e42a918 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -47,6 +47,7 @@
 #include <linux/memory.h>
 #include <linux/ftrace.h>
 #include <linux/cpu.h>
+#include <linux/jump_label.h>
 
 #include <asm-generic/sections.h>
 #include <asm/cacheflush.h>
diff --git a/kernel/module.c b/kernel/module.c
index d0b5f8db11b4..eba134157ef6 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -55,6 +55,7 @@
 #include <linux/async.h>
 #include <linux/percpu.h>
 #include <linux/kmemleak.h>
+#include <linux/jump_label.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/module.h>
@@ -2308,6 +2309,11 @@ static void find_module_sections(struct module *mod, struct load_info *info)
                                         sizeof(*mod->tracepoints),
                                         &mod->num_tracepoints);
 #endif
+#ifdef HAVE_JUMP_LABEL
+        mod->jump_entries = section_objs(info, "__jump_table",
+                                        sizeof(*mod->jump_entries),
+                                        &mod->num_jump_entries);
+#endif
 #ifdef CONFIG_EVENT_TRACING
         mod->trace_events = section_objs(info, "_ftrace_events",
                                          sizeof(*mod->trace_events),
diff --git a/scripts/gcc-goto.sh b/scripts/gcc-goto.sh
new file mode 100644
index 000000000000..8e82424be7aa
--- /dev/null
+++ b/scripts/gcc-goto.sh
@@ -0,0 +1,5 @@
+#!/bin/sh
+# Test for gcc 'asm goto' suport
+# Copyright (C) 2010, Jason Baron <jbaron@redhat.com>
+
+echo "int main(void) { entry: asm goto (\"\"::::entry); return 0; }" | $1 -x c - -c -o /dev/null >/dev/null 2>&1 && echo "y"