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Subject: random: Make it work on rt
From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 21 Aug 2012 20:38:50 +0200
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>
---
drivers/char/random.c | 11 +++++------
drivers/hv/hv.c | 4 +++-
drivers/hv/vmbus_drv.c | 4 +++-
include/linux/irqdesc.h | 1 +
include/linux/random.h | 2 +-
kernel/irq/handle.c | 8 +++++++-
kernel/irq/manage.c | 6 ++++++
7 files changed, 26 insertions(+), 10 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1215,28 +1215,27 @@ static __u32 get_reg(struct fast_pool *f
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);
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -112,10 +112,12 @@ int hv_post_message(union hv_connection_
static void hv_stimer0_isr(void)
{
struct hv_per_cpu_context *hv_cpu;
+ struct pt_regs *regs = get_irq_regs();
+ u64 ip = regs ? instruction_pointer(regs) : 0;
hv_cpu = this_cpu_ptr(hv_context.cpu_context);
hv_cpu->clk_evt->event_handler(hv_cpu->clk_evt);
- add_interrupt_randomness(stimer0_vector, 0);
+ add_interrupt_randomness(stimer0_vector, 0, ip);
}
static int hv_ce_set_next_event(unsigned long delta,
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -972,6 +972,8 @@ 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))
@@ -1015,7 +1017,7 @@ 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);
}
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -70,6 +70,7 @@ 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;
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -32,7 +32,7 @@ static inline void add_latent_entropy(vo
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);
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -185,10 +185,16 @@ irqreturn_t handle_irq_event_percpu(stru
{
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);
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1065,6 +1065,12 @@ 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);
}
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