blob: cf63d23114c5227aee556c8d4e8a6cff34e32df7 [file] [log] [blame]
From f5f930389ce6685b097ab93e65a743ff0e83d9f8 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 21 Aug 2012 20:38:50 +0200
Subject: [PATCH] random: Make it work on rt
Delegate the random insertion to the forced threaded interrupt
handler. Store the return IP of the hard interrupt handler in the irq
descriptor and feed it into the random generator as a source of
entropy.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 789b3b14ac15..d7f44305e33e 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1108,28 +1108,27 @@ static __u32 get_reg(struct fast_pool *f, struct pt_regs *regs)
return *ptr;
}
-void add_interrupt_randomness(int irq, int irq_flags)
+void add_interrupt_randomness(int irq, int irq_flags, __u64 ip)
{
struct entropy_store *r;
struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness);
- struct pt_regs *regs = get_irq_regs();
unsigned long now = jiffies;
cycles_t cycles = random_get_entropy();
__u32 c_high, j_high;
- __u64 ip;
unsigned long seed;
int credit = 0;
if (cycles == 0)
- cycles = get_reg(fast_pool, regs);
+ cycles = get_reg(fast_pool, NULL);
c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0;
j_high = (sizeof(now) > 4) ? now >> 32 : 0;
fast_pool->pool[0] ^= cycles ^ j_high ^ irq;
fast_pool->pool[1] ^= now ^ c_high;
- ip = regs ? instruction_pointer(regs) : _RET_IP_;
+ if (!ip)
+ ip = _RET_IP_;
fast_pool->pool[2] ^= ip;
fast_pool->pool[3] ^= (sizeof(ip) > 4) ? ip >> 32 :
- get_reg(fast_pool, regs);
+ get_reg(fast_pool, NULL);
fast_mix(fast_pool);
add_interrupt_bench(cycles);
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 0087b49095eb..47dad48958e8 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -968,6 +968,8 @@ static void vmbus_isr(void)
void *page_addr = hv_cpu->synic_event_page;
struct hv_message *msg;
union hv_synic_event_flags *event;
+ struct pt_regs *regs = get_irq_regs();
+ u64 ip = regs ? instruction_pointer(regs) : 0;
bool handled = false;
if (unlikely(page_addr == NULL))
@@ -1011,7 +1013,7 @@ static void vmbus_isr(void)
tasklet_schedule(&hv_cpu->msg_dpc);
}
- add_interrupt_randomness(HYPERVISOR_CALLBACK_VECTOR, 0);
+ add_interrupt_randomness(HYPERVISOR_CALLBACK_VECTOR, 0, ip);
}
diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index c9be57931b58..eeeb540971ae 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -66,6 +66,7 @@ struct irq_desc {
unsigned int irqs_unhandled;
atomic_t threads_handled;
int threads_handled_last;
+ u64 random_ip;
raw_spinlock_t lock;
struct cpumask *percpu_enabled;
const struct cpumask *percpu_affinity;
diff --git a/include/linux/random.h b/include/linux/random.h
index 4aecc339558d..fc779c086593 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -31,7 +31,7 @@ static inline void add_latent_entropy(void) {}
extern void add_input_randomness(unsigned int type, unsigned int code,
unsigned int value) __latent_entropy;
-extern void add_interrupt_randomness(int irq, int irq_flags) __latent_entropy;
+extern void add_interrupt_randomness(int irq, int irq_flags, __u64 ip) __latent_entropy;
extern void get_random_bytes(void *buf, int nbytes);
extern int wait_for_random_bytes(void);
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index d3f24905852c..f87aa8fdcc51 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -181,10 +181,16 @@ irqreturn_t handle_irq_event_percpu(struct irq_desc *desc)
{
irqreturn_t retval;
unsigned int flags = 0;
+ struct pt_regs *regs = get_irq_regs();
+ u64 ip = regs ? instruction_pointer(regs) : 0;
retval = __handle_irq_event_percpu(desc, &flags);
- add_interrupt_randomness(desc->irq_data.irq, flags);
+#ifdef CONFIG_PREEMPT_RT_FULL
+ desc->random_ip = ip;
+#else
+ add_interrupt_randomness(desc->irq_data.irq, flags, ip);
+#endif
if (!noirqdebug)
note_interrupt(desc, retval);
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 71c6dfd366af..6346a1f3d15b 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1025,6 +1025,12 @@ static int irq_thread(void *data)
if (action_ret == IRQ_WAKE_THREAD)
irq_wake_secondary(desc, action);
+#ifdef CONFIG_PREEMPT_RT_FULL
+ migrate_disable();
+ add_interrupt_randomness(action->irq, 0,
+ desc->random_ip ^ (unsigned long) action);
+ migrate_enable();
+#endif
wake_threads_waitq(desc);
}
--
2.15.0