| 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/vmbus_drv.c | 4 +++- |
| include/linux/irqdesc.h | 1 + |
| include/linux/random.h | 2 +- |
| kernel/irq/handle.c | 8 +++++++- |
| kernel/irq/manage.c | 6 ++++++ |
| 6 files changed, 23 insertions(+), 9 deletions(-) |
| |
| --- a/drivers/char/random.c |
| +++ b/drivers/char/random.c |
| @@ -1109,28 +1109,27 @@ static __u32 get_reg(struct fast_pool *f |
| return *(ptr + f->reg_idx++); |
| } |
| |
| -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/vmbus_drv.c |
| +++ b/drivers/hv/vmbus_drv.c |
| @@ -970,6 +970,8 @@ 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)) |
| @@ -1013,7 +1015,7 @@ 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 |
| @@ -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; |
| --- a/include/linux/random.h |
| +++ b/include/linux/random.h |
| @@ -31,7 +31,7 @@ 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 add_random_ready_callback(struct random_ready_callback *rdy); |
| --- a/kernel/irq/handle.c |
| +++ b/kernel/irq/handle.c |
| @@ -181,10 +181,16 @@ 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 |
| @@ -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); |
| } |
| |