diff --git a/arch/Kconfig b/arch/Kconfig
index 11d349561ece37a33c7f43eeeeee97a16fe83b55..659bdd079277ebdbec01f8a5c9dd38af1a19c888 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -383,6 +383,24 @@ config GCC_PLUGIN_SANCOV
gcc-4.5 on). It is based on the commit "Add fuzzing coverage support"
by Dmitry Vyukov <dvyukov@google.com>.
+config GCC_PLUGIN_LATENT_ENTROPY
+ bool "Generate some entropy during boot and runtime"
+ depends on GCC_PLUGINS
+ help
+ By saying Y here the kernel will instrument some kernel code to
+ extract some entropy from both original and artificially created
+ program state. This will help especially embedded systems where
+ there is little 'natural' source of entropy normally. The cost
+ is some slowdown of the boot process (about 0.5%) and fork and
+ irq processing.
+
+ Note that entropy extracted this way is not cryptographically
+ secure!
+
+ This plugin was ported from grsecurity/PaX. More information at:
+ * https://grsecurity.net/
+ * https://pax.grsecurity.net/
+
config HAVE_CC_STACKPROTECTOR
bool
help
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 6913f6725ce180cbb9ec8c2ee8d9d13e28ae93ab..1925341dbb9c9df7ceb05975cf95c0ff8a3339a5 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -14,6 +14,11 @@ CFLAGS_prom_init.o += -fPIC
CFLAGS_btext.o += -fPIC
endif
+CFLAGS_cputable.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
+CFLAGS_init.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
+CFLAGS_btext.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
+CFLAGS_prom.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
+
ifdef CONFIG_FUNCTION_TRACER
# Do not trace early boot code
CFLAGS_REMOVE_cputable.o = -mno-sched-epilog $(CC_FLAGS_FTRACE)
diff --git a/block/blk-softirq.c b/block/blk-softirq.c
index 96631e6a22b9628f124eb7d0b106261d43cfb21f..06cf9807f49a3be1742a632f9be61c0232fcaf5c 100644
--- a/block/blk-softirq.c
+++ b/block/blk-softirq.c
@@ -18,7 +18,7 @@ static DEFINE_PER_CPU(struct list_head, blk_cpu_done);
* Softirq action handler - move entries to local list and loop over them
* while passing them to the queue registered handler.
*/
-static void blk_done_softirq(struct softirq_action *h)
+static __latent_entropy void blk_done_softirq(struct softirq_action *h)
{
struct list_head *cpu_list, local_list;
diff --git a/drivers/char/random.c b/drivers/char/random.c
index d131e152c8ce6a3e70a7e0fe287275269f0c40c6..d6876d50622075f1b490bf7a19831b4e8784adb6 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -479,8 +479,8 @@ static ssize_t _extract_entropy(struct entropy_store *r, void *buf,
static void crng_reseed(struct crng_state *crng, struct entropy_store *r);
static void push_to_pool(struct work_struct *work);
-static __u32 input_pool_data[INPUT_POOL_WORDS];
-static __u32 blocking_pool_data[OUTPUT_POOL_WORDS];
+static __u32 input_pool_data[INPUT_POOL_WORDS] __latent_entropy;
+static __u32 blocking_pool_data[OUTPUT_POOL_WORDS] __latent_entropy;
static struct entropy_store input_pool = {
.poolinfo = &poolinfo_table[0],
diff --git a/fs/namespace.c b/fs/namespace.c
index 58aca9c931acaecc62bf02717c9cfa9d58baf8cf..e6c234b1a6456c1364bcc06b029f3cc4a155d5bd 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2824,6 +2824,7 @@ static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns)
return new_ns;
}
+__latent_entropy
struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
struct user_namespace *user_ns, struct fs_struct *new_fs)
{
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index 573c5a18908fd53970fefea291805c500fd1d7f9..432f5c97e18f4f75fd68b1c1101cf828fb3d4fa0 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -188,6 +188,13 @@
#endif /* GCC_VERSION >= 40300 */
#if GCC_VERSION >= 40500
+
+#ifndef __CHECKER__
+#ifdef LATENT_ENTROPY_PLUGIN
+#define __latent_entropy __attribute__((latent_entropy))
+#endif
+#endif
+
/*
* Mark a position in code as unreachable. This can be used to
* suppress control flow warnings after asm blocks that transfer
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index f1bfa15b6f9b7fd563fa5c281d336895704e606e..cf0fa5d86059b6672773025b625027f6301074c1 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -429,6 +429,10 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
# define __attribute_const__ /* unimplemented */
#endif
+#ifndef __latent_entropy
+# define __latent_entropy
+#endif
+
/*
* Tell gcc if a function is cold. The compiler will assume any path
* directly leading to the call is unlikely.
diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index aca2a6a1d0358f181264877965ff3e2ba882a8a0..6e84b2cae6ad62b529298b662856dc857c3091b6 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -105,7 +105,7 @@ struct files_struct *get_files_struct(struct task_struct *);
void put_files_struct(struct files_struct *fs);
void reset_files_struct(struct files_struct *);
int unshare_files(struct files_struct **);
-struct files_struct *dup_fd(struct files_struct *, int *);
+struct files_struct *dup_fd(struct files_struct *, int *) __latent_entropy;
void do_close_on_exec(struct files_struct *);
int iterate_fd(struct files_struct *, unsigned,
int (*)(const void *, struct file *, unsigned),
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 1dbf52f9c24b88a0f4a299bae5ec3bfdcea1e566..e0341af6950e2116a43b3b0281f57fea8099c06f 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -437,7 +437,7 @@ extern void disk_flush_events(struct gendisk *disk, unsigned int mask);
extern unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask);
/* drivers/char/random.c */
-extern void add_disk_randomness(struct gendisk *disk);
+extern void add_disk_randomness(struct gendisk *disk) __latent_entropy;
extern void rand_initialize_disk(struct gendisk *disk);
static inline sector_t get_start_sect(struct block_device *bdev)
diff --git a/include/linux/init.h b/include/linux/init.h
index 024a0b5b3ed0d41a8f9837c2c61cf4704e615b25..e30104ceb86dcb3076f7950d34d2776735b132ff 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -39,7 +39,7 @@
/* These are for everybody (although not all archs will actually
discard it in modules) */
-#define __init __section(.init.text) __cold notrace
+#define __init __section(.init.text) __cold notrace __latent_entropy
#define __initdata __section(.init.data)
#define __initconst __section(.init.rodata)
#define __exitdata __section(.exit.data)
@@ -75,7 +75,8 @@
#define __exit __section(.exit.text) __exitused __cold notrace
/* Used for MEMORY_HOTPLUG */
-#define __meminit __section(.meminit.text) __cold notrace
+#define __meminit __section(.meminit.text) __cold notrace \
+ __latent_entropy
#define __meminitdata __section(.meminit.data)
#define __meminitconst __section(.meminit.rodata)
#define __memexit __section(.memexit.text) __exitused __cold notrace
diff --git a/include/linux/random.h b/include/linux/random.h
index f7bb7a355cf71381100730a2379ba206bc3258ea..7bd2403e4fef1ad7fb0a5f03b4e104e96234d26b 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -18,9 +18,20 @@ struct random_ready_callback {
};
extern void add_device_randomness(const void *, unsigned int);
+
+#if defined(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) && !defined(__CHECKER__)
+static inline void add_latent_entropy(void)
+{
+ add_device_randomness((const void *)&latent_entropy,
+ sizeof(latent_entropy));
+}
+#else
+static inline void add_latent_entropy(void) {}
+#endif
+
extern void add_input_randomness(unsigned int type, unsigned int code,
- unsigned int value);
-extern void add_interrupt_randomness(int irq, int irq_flags);
+ unsigned int value) __latent_entropy;
+extern void add_interrupt_randomness(int irq, int irq_flags) __latent_entropy;
extern void get_random_bytes(void *buf, int nbytes);
extern int add_random_ready_callback(struct random_ready_callback *rdy);
diff --git a/init/main.c b/init/main.c
index a8a58e2794a50469d465fad1a6939a4b68ec1114..2858be732f6d25dd8431cd994645c8c6af3828c2 100644
--- a/init/main.c
+++ b/init/main.c
@@ -789,6 +789,7 @@ int __init_or_module do_one_initcall(initcall_t fn)
}
WARN(msgbuf[0], "initcall %pF returned with %s\n", fn, msgbuf);
+ add_latent_entropy();
return ret;
}
diff --git a/kernel/fork.c b/kernel/fork.c
index 6d42242485cb2863e940ae0d54983a2d34789096..623259fc794d034f7b4ab9144e2a61a7233381b6 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -547,7 +547,8 @@ free_tsk:
}
#ifdef CONFIG_MMU
-static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
+static __latent_entropy int dup_mmap(struct mm_struct *mm,
+ struct mm_struct *oldmm)
{
struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
struct rb_node **rb_link, *rb_parent;
@@ -1441,7 +1442,8 @@ init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
* parts of the process environment (as per the clone
* flags). The actual kick-off is left to the caller.
*/
-static struct task_struct *copy_process(unsigned long clone_flags,
+static __latent_entropy struct task_struct *copy_process(
+ unsigned long clone_flags,
unsigned long stack_start,
unsigned long stack_size,
int __user *child_tidptr,
@@ -1926,6 +1928,7 @@ long _do_fork(unsigned long clone_flags,
p = copy_process(clone_flags, stack_start, stack_size,
child_tidptr, NULL, trace, tls, NUMA_NO_NODE);
+ add_latent_entropy();
/*
* Do this prior waking up the new thread - the thread pointer
* might get invalid after that point, if the thread exits quickly.
diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
index 944b1b491ed84b3d2d1cf977a9838a30cf405121..1898559e6b60ddc52884f6977fca21e57c6f1f90 100644
--- a/kernel/rcu/tiny.c
+++ b/kernel/rcu/tiny.c
@@ -170,7 +170,7 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp)
false));
}
-static void rcu_process_callbacks(struct softirq_action *unused)
+static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused)
{
__rcu_process_callbacks(&rcu_sched_ctrlblk);
__rcu_process_callbacks(&rcu_bh_ctrlblk);
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 7e2e03879c2e55bf259f257868b8b457d5353b07..69a5611a7e7c03dcf950d94badfcce3445863440 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3013,7 +3013,7 @@ __rcu_process_callbacks(struct rcu_state *rsp)
/*
* Do RCU core processing for the current CPU.
*/
-static void rcu_process_callbacks(struct softirq_action *unused)
+static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused)
{
struct rcu_state *rsp;
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 502e95a6e9276cd5ca36dfebbe0f8425610b9c33..2d4ad72f8f3c8c585f0b8876d2255614944cf157 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8522,7 +8522,7 @@ static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) { }
* run_rebalance_domains is triggered when needed from the scheduler tick.
* Also triggered for nohz idle balancing (with nohz_balancing_kick set).
*/
-static void run_rebalance_domains(struct softirq_action *h)
+static __latent_entropy void run_rebalance_domains(struct softirq_action *h)
{
struct rq *this_rq = this_rq();
enum cpu_idle_type idle = this_rq->idle_balance ?
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 66762645f9e86c30505610736f0380a2cdd1ae00..1bf81ef913755ae797c90e2affc3330f54d3a7df 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -496,7 +496,7 @@ void __tasklet_hi_schedule_first(struct tasklet_struct *t)
}
EXPORT_SYMBOL(__tasklet_hi_schedule_first);
-static void tasklet_action(struct softirq_action *a)
+static __latent_entropy void tasklet_action(struct softirq_action *a)
{
struct tasklet_struct *list;
@@ -532,7 +532,7 @@ static void tasklet_action(struct softirq_action *a)
}
}
-static void tasklet_hi_action(struct softirq_action *a)
+static __latent_entropy void tasklet_hi_action(struct softirq_action *a)
{
struct tasklet_struct *list;
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 32bf6f75a8fec255c6d5fbf38e9fecd9e1e848fa..2d47980a1bc423df44e8e1324537f4e185b338ae 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1633,7 +1633,7 @@ static inline void __run_timers(struct timer_base *base)
/*
* This function runs timers and the timer-tq in bottom half context.
*/
-static void run_timer_softirq(struct softirq_action *h)
+static __latent_entropy void run_timer_softirq(struct softirq_action *h)
{
struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]);
diff --git a/lib/irq_poll.c b/lib/irq_poll.c
index 2be55692aa43fc5f9d4f9fbe4d337e38fe359b45..1d6565e810309eb710523a814983849d76101c6b 100644
--- a/lib/irq_poll.c
+++ b/lib/irq_poll.c
@@ -74,7 +74,7 @@ void irq_poll_complete(struct irq_poll *iop)
}
EXPORT_SYMBOL(irq_poll_complete);
-static void irq_poll_softirq(struct softirq_action *h)
+static void __latent_entropy irq_poll_softirq(struct softirq_action *h)
{
struct list_head *list = this_cpu_ptr(&blk_cpu_iopoll);
int rearm = 0, budget = irq_poll_budget;
diff --git a/lib/random32.c b/lib/random32.c
index 915982b304bbb16a9d7924b3c1957857189ab6ba..fa594b1140e648899410d15920ea5705d7202661 100644
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -47,7 +47,7 @@ static inline void prandom_state_selftest(void)
}
#endif
-static DEFINE_PER_CPU(struct rnd_state, net_rand_state);
+static DEFINE_PER_CPU(struct rnd_state, net_rand_state) __latent_entropy;
/**
* prandom_u32_state - seeded pseudo-random number generator.
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ca423cc20b5985b9ba5528e7648881f05445a50d..2b3bf6767d5441a876890dce16d9de2d60f1e2bc 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -91,6 +91,11 @@ EXPORT_PER_CPU_SYMBOL(_numa_mem_);
int _node_numa_mem_[MAX_NUMNODES];
#endif
+#ifdef CONFIG_GCC_PLUGIN_LATENT_ENTROPY
+volatile u64 latent_entropy __latent_entropy;
+EXPORT_SYMBOL(latent_entropy);
+#endif
+
/*
* Array of node states.
*/
diff --git a/net/core/dev.c b/net/core/dev.c
index f1fe26f6645883a54126300adc030f1c3a04652d..4bc19a164ba5dc1dbf5d0f3f378f61e49d3be9dd 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3845,7 +3845,7 @@ int netif_rx_ni(struct sk_buff *skb)
}
EXPORT_SYMBOL(netif_rx_ni);
-static void net_tx_action(struct softirq_action *h)
+static __latent_entropy void net_tx_action(struct softirq_action *h)
{
struct softnet_data *sd = this_cpu_ptr(&softnet_data);
@@ -5198,7 +5198,7 @@ out_unlock:
return work;
}
-static void net_rx_action(struct softirq_action *h)
+static __latent_entropy void net_rx_action(struct softirq_action *h)
{
struct softnet_data *sd = this_cpu_ptr(&softnet_data);
unsigned long time_limit = jiffies + 2;
diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins
index 61f0e6db909bbf0a7016d60f4b58a4c4bd3c0dba..060d2cb373dbe3fe788b7ad01b7868eca3b73166 100644
--- a/scripts/Makefile.gcc-plugins
+++ b/scripts/Makefile.gcc-plugins
@@ -6,6 +6,12 @@ ifdef CONFIG_GCC_PLUGINS
gcc-plugin-$(CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) += cyc_complexity_plugin.so
+ gcc-plugin-$(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) += latent_entropy_plugin.so
+ gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) += -DLATENT_ENTROPY_PLUGIN
+ ifdef CONFIG_PAX_LATENT_ENTROPY
+ DISABLE_LATENT_ENTROPY_PLUGIN += -fplugin-arg-latent_entropy_plugin-disable
+ endif
+
ifdef CONFIG_GCC_PLUGIN_SANCOV
ifeq ($(CFLAGS_KCOV),)
# It is needed because of the gcc-plugin.sh and gcc version checks.
@@ -21,7 +27,8 @@ ifdef CONFIG_GCC_PLUGINS
GCC_PLUGINS_CFLAGS := $(strip $(addprefix -fplugin=$(objtree)/scripts/gcc-plugins/, $(gcc-plugin-y)) $(gcc-plugin-cflags-y))
- export PLUGINCC GCC_PLUGINS_CFLAGS GCC_PLUGIN GCC_PLUGIN_SUBDIR SANCOV_PLUGIN
+ export PLUGINCC GCC_PLUGINS_CFLAGS GCC_PLUGIN GCC_PLUGIN_SUBDIR
+ export SANCOV_PLUGIN DISABLE_LATENT_ENTROPY_PLUGIN
ifneq ($(PLUGINCC),)
# SANCOV_PLUGIN can be only in CFLAGS_KCOV because avoid duplication.
diff --git a/scripts/gcc-plugins/latent_entropy_plugin.c b/scripts/gcc-plugins/latent_entropy_plugin.c
new file mode 100644
index 0000000000000000000000000000000000000000..ff1939b804aefe75631431b45e6f7ce80cc133f3
--- /dev/null
+++ b/scripts/gcc-plugins/latent_entropy_plugin.c
@@ -0,0 +1,640 @@
+/*
+ * Copyright 2012-2016 by the PaX Team <pageexec@freemail.hu>
+ * Copyright 2016 by Emese Revfy <re.emese@gmail.com>
+ * Licensed under the GPL v2
+ *
+ * Note: the choice of the license means that the compilation process is
+ * NOT 'eligible' as defined by gcc's library exception to the GPL v3,
+ * but for the kernel it doesn't matter since it doesn't link against
+ * any of the gcc libraries
+ *
+ * This gcc plugin helps generate a little bit of entropy from program state,
+ * used throughout the uptime of the kernel. Here is an instrumentation example:
+ *
+ * before:
+ * void __latent_entropy test(int argc, char *argv[])
+ * {
+ * if (argc <= 1)
+ * printf("%s: no command arguments :(\n", *argv);
+ * else
+ * printf("%s: %d command arguments!\n", *argv, args - 1);
+ * }
+ *
+ * after:
+ * void __latent_entropy test(int argc, char *argv[])
+ * {
+ * // latent_entropy_execute() 1.
+ * unsigned long local_entropy;
+ * // init_local_entropy() 1.
+ * void *local_entropy_frameaddr;
+ * // init_local_entropy() 3.
+ * unsigned long tmp_latent_entropy;
+ *
+ * // init_local_entropy() 2.
+ * local_entropy_frameaddr = __builtin_frame_address(0);
+ * local_entropy = (unsigned long) local_entropy_frameaddr;
+ *
+ * // init_local_entropy() 4.
+ * tmp_latent_entropy = latent_entropy;
+ * // init_local_entropy() 5.
+ * local_entropy ^= tmp_latent_entropy;
+ *
+ * // latent_entropy_execute() 3.
+ * if (argc <= 1) {
+ * // perturb_local_entropy()
+ * local_entropy += 4623067384293424948;
+ * printf("%s: no command arguments :(\n", *argv);
+ * // perturb_local_entropy()
+ * } else {
+ * local_entropy ^= 3896280633962944730;
+ * printf("%s: %d command arguments!\n", *argv, args - 1);
+ * }
+ *
+ * // latent_entropy_execute() 4.
+ * tmp_latent_entropy = rol(tmp_latent_entropy, local_entropy);
+ * latent_entropy = tmp_latent_entropy;
+ * }
+ *
+ * TODO:
+ * - add ipa pass to identify not explicitly marked candidate functions
+ * - mix in more program state (function arguments/return values,
+ * loop variables, etc)
+ * - more instrumentation control via attribute parameters
+ *
+ * BUGS:
+ * - none known
+ *
+ * Options:
+ * -fplugin-arg-latent_entropy_plugin-disable
+ *
+ * Attribute: __attribute__((latent_entropy))
+ * The latent_entropy gcc attribute can be only on functions and variables.
+ * If it is on a function then the plugin will instrument it. If the attribute
+ * is on a variable then the plugin will initialize it with a random value.
+ * The variable must be an integer, an integer array type or a structure
+ * with integer fields.
+ */
+
+#include "gcc-common.h"
+
+int plugin_is_GPL_compatible;
+
+static GTY(()) tree latent_entropy_decl;
+
+static struct plugin_info latent_entropy_plugin_info = {
+ .version = "201606141920vanilla",
+ .help = "disable\tturn off latent entropy instrumentation\n",
+};
+
+static unsigned HOST_WIDE_INT seed;
+/*
+ * get_random_seed() (this is a GCC function) generates the seed.
+ * This is a simple random generator without any cryptographic security because
+ * the entropy doesn't come from here.
+ */
+static unsigned HOST_WIDE_INT get_random_const(void)
+{
+ unsigned int i;
+ unsigned HOST_WIDE_INT ret = 0;
+
+ for (i = 0; i < 8 * sizeof(ret); i++) {
+ ret = (ret << 1) | (seed & 1);
+ seed >>= 1;
+ if (ret & 1)
+ seed ^= 0xD800000000000000ULL;
+ }
+
+ return ret;
+}
+
+static tree tree_get_random_const(tree type)
+{
+ unsigned long long mask;
+
+ mask = 1ULL << (TREE_INT_CST_LOW(TYPE_SIZE(type)) - 1);
+ mask = 2 * (mask - 1) + 1;
+
+ if (TYPE_UNSIGNED(type))
+ return build_int_cstu(type, mask & get_random_const());
+ return build_int_cst(type, mask & get_random_const());
+}
+
+static tree handle_latent_entropy_attribute(tree *node, tree name,
+ tree args __unused,
+ int flags __unused,
+ bool *no_add_attrs)
+{
+ tree type;
+#if BUILDING_GCC_VERSION <= 4007
+ VEC(constructor_elt, gc) *vals;
+#else
+ vec<constructor_elt, va_gc> *vals;
+#endif
+
+ switch (TREE_CODE(*node)) {
+ default:
+ *no_add_attrs = true;
+ error("%qE attribute only applies to functions and variables",
+ name);
+ break;
+
+ case VAR_DECL:
+ if (DECL_INITIAL(*node)) {
+ *no_add_attrs = true;
+ error("variable %qD with %qE attribute must not be initialized",
+ *node, name);
+ break;
+ }
+
+ if (!TREE_STATIC(*node)) {
+ *no_add_attrs = true;
+ error("variable %qD with %qE attribute must not be local",
+ *node, name);
+ break;
+ }
+
+ type = TREE_TYPE(*node);
+ switch (TREE_CODE(type)) {
+ default:
+ *no_add_attrs = true;
+ error("variable %qD with %qE attribute must be an integer or a fixed length integer array type or a fixed sized structure with integer fields",
+ *node, name);
+ break;
+
+ case RECORD_TYPE: {
+ tree fld, lst = TYPE_FIELDS(type);
+ unsigned int nelt = 0;
+
+ for (fld = lst; fld; nelt++, fld = TREE_CHAIN(fld)) {
+ tree fieldtype;
+
+ fieldtype = TREE_TYPE(fld);
+ if (TREE_CODE(fieldtype) == INTEGER_TYPE)
+ continue;
+
+ *no_add_attrs = true;
+ error("structure variable %qD with %qE attribute has a non-integer field %qE",
+ *node, name, fld);
+ break;
+ }
+
+ if (fld)
+ break;
+
+#if BUILDING_GCC_VERSION <= 4007
+ vals = VEC_alloc(constructor_elt, gc, nelt);
+#else
+ vec_alloc(vals, nelt);
+#endif
+
+ for (fld = lst; fld; fld = TREE_CHAIN(fld)) {
+ tree random_const, fld_t = TREE_TYPE(fld);
+
+ random_const = tree_get_random_const(fld_t);
+ CONSTRUCTOR_APPEND_ELT(vals, fld, random_const);
+ }
+
+ /* Initialize the fields with random constants */
+ DECL_INITIAL(*node) = build_constructor(type, vals);
+ break;
+ }
+
+ /* Initialize the variable with a random constant */
+ case INTEGER_TYPE:
+ DECL_INITIAL(*node) = tree_get_random_const(type);
+ break;
+
+ case ARRAY_TYPE: {
+ tree elt_type, array_size, elt_size;
+ unsigned int i, nelt;
+ HOST_WIDE_INT array_size_int, elt_size_int;
+
+ elt_type = TREE_TYPE(type);
+ elt_size = TYPE_SIZE_UNIT(TREE_TYPE(type));
+ array_size = TYPE_SIZE_UNIT(type);
+
+ if (TREE_CODE(elt_type) != INTEGER_TYPE || !array_size
+ || TREE_CODE(array_size) != INTEGER_CST) {
+ *no_add_attrs = true;
+ error("array variable %qD with %qE attribute must be a fixed length integer array type",
+ *node, name);
+ break;
+ }
+
+ array_size_int = TREE_INT_CST_LOW(array_size);
+ elt_size_int = TREE_INT_CST_LOW(elt_size);
+ nelt = array_size_int / elt_size_int;
+
+#if BUILDING_GCC_VERSION <= 4007
+ vals = VEC_alloc(constructor_elt, gc, nelt);
+#else
+ vec_alloc(vals, nelt);
+#endif
+
+ for (i = 0; i < nelt; i++) {
+ tree cst = size_int(i);
+ tree rand_cst = tree_get_random_const(elt_type);
+
+ CONSTRUCTOR_APPEND_ELT(vals, cst, rand_cst);
+ }
+
+ /*
+ * Initialize the elements of the array with random
+ * constants
+ */
+ DECL_INITIAL(*node) = build_constructor(type, vals);
+ break;
+ }
+ }
+ break;
+
+ case FUNCTION_DECL:
+ break;
+ }
+
+ return NULL_TREE;
+}
+
+static struct attribute_spec latent_entropy_attr = {
+ .name = "latent_entropy",
+ .min_length = 0,
+ .max_length = 0,
+ .decl_required = true,
+ .type_required = false,
+ .function_type_required = false,
+ .handler = handle_latent_entropy_attribute,
+#if BUILDING_GCC_VERSION >= 4007
+ .affects_type_identity = false
+#endif
+};
+
+static void register_attributes(void *event_data __unused, void *data __unused)
+{
+ register_attribute(&latent_entropy_attr);
+}
+
+static bool latent_entropy_gate(void)
+{
+ tree list;
+
+ /* don't bother with noreturn functions for now */
+ if (TREE_THIS_VOLATILE(current_function_decl))
+ return false;
+
+ /* gcc-4.5 doesn't discover some trivial noreturn functions */
+ if (EDGE_COUNT(EXIT_BLOCK_PTR_FOR_FN(cfun)->preds) == 0)
+ return false;
+
+ list = DECL_ATTRIBUTES(current_function_decl);
+ return lookup_attribute("latent_entropy", list) != NULL_TREE;
+}
+
+static tree create_var(tree type, const char *name)
+{
+ tree var;
+
+ var = create_tmp_var(type, name);
+ add_referenced_var(var);
+ mark_sym_for_renaming(var);
+ return var;
+}
+
+/*
+ * Set up the next operation and its constant operand to use in the latent
+ * entropy PRNG. When RHS is specified, the request is for perturbing the
+ * local latent entropy variable, otherwise it is for perturbing the global
+ * latent entropy variable where the two operands are already given by the
+ * local and global latent entropy variables themselves.
+ *
+ * The operation is one of add/xor/rol when instrumenting the local entropy
+ * variable and one of add/xor when perturbing the global entropy variable.
+ * Rotation is not used for the latter case because it would transmit less
+ * entropy to the global variable than the other two operations.
+ */
+static enum tree_code get_op(tree *rhs)
+{
+ static enum tree_code op;
+ unsigned HOST_WIDE_INT random_const;
+
+ random_const = get_random_const();
+
+ switch (op) {
+ case BIT_XOR_EXPR:
+ op = PLUS_EXPR;
+ break;
+
+ case PLUS_EXPR:
+ if (rhs) {
+ op = LROTATE_EXPR;
+ /*
+ * This code limits the value of random_const to
+ * the size of a wide int for the rotation
+ */
+ random_const &= HOST_BITS_PER_WIDE_INT - 1;
+ break;
+ }
+
+ case LROTATE_EXPR:
+ default:
+ op = BIT_XOR_EXPR;
+ break;
+ }
+ if (rhs)
+ *rhs = build_int_cstu(unsigned_intDI_type_node, random_const);
+ return op;
+}
+
+static gimple create_assign(enum tree_code code, tree lhs, tree op1,
+ tree op2)
+{
+ return gimple_build_assign_with_ops(code, lhs, op1, op2);
+}
+
+static void perturb_local_entropy(basic_block bb, tree local_entropy)
+{
+ gimple_stmt_iterator gsi;
+ gimple assign;
+ tree rhs;
+ enum tree_code op;
+
+ op = get_op(&rhs);
+ assign = create_assign(op, local_entropy, local_entropy, rhs);
+ gsi = gsi_after_labels(bb);
+ gsi_insert_before(&gsi, assign, GSI_NEW_STMT);
+ update_stmt(assign);
+}
+
+static void __perturb_latent_entropy(gimple_stmt_iterator *gsi,
+ tree local_entropy)
+{
+ gimple assign;
+ tree temp;
+ enum tree_code op;
+
+ /* 1. create temporary copy of latent_entropy */
+ temp = create_var(unsigned_intDI_type_node, "tmp_latent_entropy");
+
+ /* 2. read... */
+ add_referenced_var(latent_entropy_decl);
+ mark_sym_for_renaming(latent_entropy_decl);
+ assign = gimple_build_assign(temp, latent_entropy_decl);
+ gsi_insert_before(gsi, assign, GSI_NEW_STMT);
+ update_stmt(assign);
+
+ /* 3. ...modify... */
+ op = get_op(NULL);
+ assign = create_assign(op, temp, temp, local_entropy);
+ gsi_insert_after(gsi, assign, GSI_NEW_STMT);
+ update_stmt(assign);
+
+ /* 4. ...write latent_entropy */
+ assign = gimple_build_assign(latent_entropy_decl, temp);
+ gsi_insert_after(gsi, assign, GSI_NEW_STMT);
+ update_stmt(assign);
+}
+
+static bool handle_tail_calls(basic_block bb, tree local_entropy)
+{
+ gimple_stmt_iterator gsi;
+
+ for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) {
+ gcall *call;
+ gimple stmt = gsi_stmt(gsi);
+
+ if (!is_gimple_call(stmt))
+ continue;
+
+ call = as_a_gcall(stmt);
+ if (!gimple_call_tail_p(call))
+ continue;
+
+ __perturb_latent_entropy(&gsi, local_entropy);
+ return true;
+ }
+
+ return false;
+}
+
+static void perturb_latent_entropy(tree local_entropy)
+{
+ edge_iterator ei;
+ edge e, last_bb_e;
+ basic_block last_bb;
+
+ gcc_assert(single_pred_p(EXIT_BLOCK_PTR_FOR_FN(cfun)));
+ last_bb_e = single_pred_edge(EXIT_BLOCK_PTR_FOR_FN(cfun));
+
+ FOR_EACH_EDGE(e, ei, last_bb_e->src->preds) {
+ if (ENTRY_BLOCK_PTR_FOR_FN(cfun) == e->src)
+ continue;
+ if (EXIT_BLOCK_PTR_FOR_FN(cfun) == e->src)
+ continue;
+
+ handle_tail_calls(e->src, local_entropy);
+ }
+
+ last_bb = single_pred(EXIT_BLOCK_PTR_FOR_FN(cfun));
+ if (!handle_tail_calls(last_bb, local_entropy)) {
+ gimple_stmt_iterator gsi = gsi_last_bb(last_bb);
+
+ __perturb_latent_entropy(&gsi, local_entropy);
+ }
+}
+
+static void init_local_entropy(basic_block bb, tree local_entropy)
+{
+ gimple assign, call;
+ tree frame_addr, rand_const, tmp, fndecl, udi_frame_addr;
+ enum tree_code op;
+ unsigned HOST_WIDE_INT rand_cst;
+ gimple_stmt_iterator gsi = gsi_after_labels(bb);
+
+ /* 1. create local_entropy_frameaddr */
+ frame_addr = create_var(ptr_type_node, "local_entropy_frameaddr");
+
+ /* 2. local_entropy_frameaddr = __builtin_frame_address() */
+ fndecl = builtin_decl_implicit(BUILT_IN_FRAME_ADDRESS);
+ call = gimple_build_call(fndecl, 1, integer_zero_node);
+ gimple_call_set_lhs(call, frame_addr);
+ gsi_insert_before(&gsi, call, GSI_NEW_STMT);
+ update_stmt(call);
+
+ udi_frame_addr = fold_convert(unsigned_intDI_type_node, frame_addr);
+ assign = gimple_build_assign(local_entropy, udi_frame_addr);
+ gsi_insert_after(&gsi, assign, GSI_NEW_STMT);
+ update_stmt(assign);
+
+ /* 3. create temporary copy of latent_entropy */
+ tmp = create_var(unsigned_intDI_type_node, "tmp_latent_entropy");
+
+ /* 4. read the global entropy variable into local entropy */
+ add_referenced_var(latent_entropy_decl);
+ mark_sym_for_renaming(latent_entropy_decl);
+ assign = gimple_build_assign(tmp, latent_entropy_decl);
+ gsi_insert_after(&gsi, assign, GSI_NEW_STMT);
+ update_stmt(assign);
+
+ /* 5. mix local_entropy_frameaddr into local entropy */
+ assign = create_assign(BIT_XOR_EXPR, local_entropy, local_entropy, tmp);
+ gsi_insert_after(&gsi, assign, GSI_NEW_STMT);
+ update_stmt(assign);
+
+ rand_cst = get_random_const();
+ rand_const = build_int_cstu(unsigned_intDI_type_node, rand_cst);
+ op = get_op(NULL);
+ assign = create_assign(op, local_entropy, local_entropy, rand_const);
+ gsi_insert_after(&gsi, assign, GSI_NEW_STMT);
+ update_stmt(assign);
+}
+
+static bool create_latent_entropy_decl(void)
+{
+ varpool_node_ptr node;
+
+ if (latent_entropy_decl != NULL_TREE)
+ return true;
+
+ FOR_EACH_VARIABLE(node) {
+ tree name, var = NODE_DECL(node);
+
+ if (DECL_NAME_LENGTH(var) < sizeof("latent_entropy") - 1)
+ continue;
+
+ name = DECL_NAME(var);
+ if (strcmp(IDENTIFIER_POINTER(name), "latent_entropy"))
+ continue;
+
+ latent_entropy_decl = var;
+ break;
+ }
+
+ return latent_entropy_decl != NULL_TREE;
+}
+
+static unsigned int latent_entropy_execute(void)
+{
+ basic_block bb;
+ tree local_entropy;
+
+ if (!create_latent_entropy_decl())
+ return 0;
+
+ /* prepare for step 2 below */
+ gcc_assert(single_succ_p(ENTRY_BLOCK_PTR_FOR_FN(cfun)));
+ bb = single_succ(ENTRY_BLOCK_PTR_FOR_FN(cfun));
+ if (!single_pred_p(bb)) {
+ split_edge(single_succ_edge(ENTRY_BLOCK_PTR_FOR_FN(cfun)));
+ gcc_assert(single_succ_p(ENTRY_BLOCK_PTR_FOR_FN(cfun)));
+ bb = single_succ(ENTRY_BLOCK_PTR_FOR_FN(cfun));
+ }
+
+ /* 1. create the local entropy variable */
+ local_entropy = create_var(unsigned_intDI_type_node, "local_entropy");
+
+ /* 2. initialize the local entropy variable */
+ init_local_entropy(bb, local_entropy);
+
+ bb = bb->next_bb;
+
+ /*
+ * 3. instrument each BB with an operation on the
+ * local entropy variable
+ */
+ while (bb != EXIT_BLOCK_PTR_FOR_FN(cfun)) {
+ perturb_local_entropy(bb, local_entropy);
+ bb = bb->next_bb;
+ };
+
+ /* 4. mix local entropy into the global entropy variable */
+ perturb_latent_entropy(local_entropy);
+ return 0;
+}
+
+static void latent_entropy_start_unit(void *gcc_data __unused,
+ void *user_data __unused)
+{
+ tree type, id;
+ int quals;
+
+ seed = get_random_seed(false);
+
+ if (in_lto_p)
+ return;
+
+ /* extern volatile u64 latent_entropy */
+ gcc_assert(TYPE_PRECISION(long_long_unsigned_type_node) == 64);
+ quals = TYPE_QUALS(long_long_unsigned_type_node) | TYPE_QUAL_VOLATILE;
+ type = build_qualified_type(long_long_unsigned_type_node, quals);
+ id = get_identifier("latent_entropy");
+ latent_entropy_decl = build_decl(UNKNOWN_LOCATION, VAR_DECL, id, type);
+
+ TREE_STATIC(latent_entropy_decl) = 1;
+ TREE_PUBLIC(latent_entropy_decl) = 1;
+ TREE_USED(latent_entropy_decl) = 1;
+ DECL_PRESERVE_P(latent_entropy_decl) = 1;
+ TREE_THIS_VOLATILE(latent_entropy_decl) = 1;
+ DECL_EXTERNAL(latent_entropy_decl) = 1;
+ DECL_ARTIFICIAL(latent_entropy_decl) = 1;
+ lang_hooks.decls.pushdecl(latent_entropy_decl);
+}
+
+#define PASS_NAME latent_entropy
+#define PROPERTIES_REQUIRED PROP_gimple_leh | PROP_cfg
+#define TODO_FLAGS_FINISH TODO_verify_ssa | TODO_verify_stmts | TODO_dump_func \
+ | TODO_update_ssa
+#include "gcc-generate-gimple-pass.h"
+
+int plugin_init(struct plugin_name_args *plugin_info,
+ struct plugin_gcc_version *version)
+{
+ bool enabled = true;
+ const char * const plugin_name = plugin_info->base_name;
+ const int argc = plugin_info->argc;
+ const struct plugin_argument * const argv = plugin_info->argv;
+ int i;
+
+ struct register_pass_info latent_entropy_pass_info;
+
+ latent_entropy_pass_info.pass = make_latent_entropy_pass();
+ latent_entropy_pass_info.reference_pass_name = "optimized";
+ latent_entropy_pass_info.ref_pass_instance_number = 1;
+ latent_entropy_pass_info.pos_op = PASS_POS_INSERT_BEFORE;
+ static const struct ggc_root_tab gt_ggc_r_gt_latent_entropy[] = {
+ {
+ .base = &latent_entropy_decl,
+ .nelt = 1,
+ .stride = sizeof(latent_entropy_decl),
+ .cb = >_ggc_mx_tree_node,
+ .pchw = >_pch_nx_tree_node
+ },
+ LAST_GGC_ROOT_TAB
+ };
+
+ if (!plugin_default_version_check(version, &gcc_version)) {
+ error(G_("incompatible gcc/plugin versions"));
+ return 1;
+ }
+
+ for (i = 0; i < argc; ++i) {
+ if (!(strcmp(argv[i].key, "disable"))) {
+ enabled = false;
+ continue;
+ }
+ error(G_("unkown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key);
+ }
+
+ register_callback(plugin_name, PLUGIN_INFO, NULL,
+ &latent_entropy_plugin_info);
+ if (enabled) {
+ register_callback(plugin_name, PLUGIN_START_UNIT,
+ &latent_entropy_start_unit, NULL);
+ register_callback(plugin_name, PLUGIN_REGISTER_GGC_ROOTS,
+ NULL, (void *)>_ggc_r_gt_latent_entropy);
+ register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL,
+ &latent_entropy_pass_info);
+ }
+ register_callback(plugin_name, PLUGIN_ATTRIBUTES, register_attributes,
+ NULL);
+
+ return 0;
+}