rt-patches/0216-random-Make-it-work-on-rt.patch

   1 From e2849410757919ff26a7731a8fef17227d080600 Mon Sep 17 00:00:00 2001
   2 From: Thomas Gleixner <tglx@linutronix.de>
   3 Date: Tue, 21 Aug 2012 20:38:50 +0200
   4 Subject: [PATCH 216/365] random: Make it work on rt
   5
   6 Delegate the random insertion to the forced threaded interrupt
   7 handler. Store the return IP of the hard interrupt handler in the irq
   8 descriptor and feed it into the random generator as a source of
   9 entropy.
  10
  11 Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
  12 ---
  13  drivers/char/random.c   | 11 +++++------
  14  include/linux/irqdesc.h |  1 +
  15  include/linux/random.h  |  2 +-
  16  kernel/irq/handle.c     |  8 +++++++-
  17  kernel/irq/manage.c     |  6 ++++++
  18  5 files changed, 20 insertions(+), 8 deletions(-)
  19
  20 diff --git a/drivers/char/random.c b/drivers/char/random.c
  21 index dd5346c..afffbc7 100644
  22 --- a/drivers/char/random.c
  23 +++ b/drivers/char/random.c
  24 @@ -891,28 +891,27 @@ static __u32 get_reg(struct fast_pool *f, struct pt_regs *regs)
  25         return *(ptr + f->reg_idx++);
  26  }
  27
  28 -void add_interrupt_randomness(int irq, int irq_flags)
  29 +void add_interrupt_randomness(int irq, int irq_flags, __u64 ip)
  30  {
  31         struct entropy_store    *r;
  32         struct fast_pool        *fast_pool = this_cpu_ptr(&irq_randomness);
  33 -       struct pt_regs          *regs = get_irq_regs();
  34         unsigned long           now = jiffies;
  35         cycles_t                cycles = random_get_entropy();
  36         __u32                   c_high, j_high;
  37 -       __u64                   ip;
  38         unsigned long           seed;
  39         int                     credit = 0;
  40
  41         if (cycles == 0)
  42 -               cycles = get_reg(fast_pool, regs);
  43 +               cycles = get_reg(fast_pool, NULL);
  44         c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0;
  45         j_high = (sizeof(now) > 4) ? now >> 32 : 0;
  46         fast_pool->pool[0] ^= cycles ^ j_high ^ irq;
  47         fast_pool->pool[1] ^= now ^ c_high;
  48 -       ip = regs ? instruction_pointer(regs) : _RET_IP_;
  49 +       if (!ip)
  50 +               ip = _RET_IP_;
  51         fast_pool->pool[2] ^= ip;
  52         fast_pool->pool[3] ^= (sizeof(ip) > 4) ? ip >> 32 :
  53 -               get_reg(fast_pool, regs);
  54 +               get_reg(fast_pool, NULL);
  55
  56         fast_mix(fast_pool);
  57         add_interrupt_bench(cycles);
  58 diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
  59 index a587a33..ad57402 100644
  60 --- a/include/linux/irqdesc.h
  61 +++ b/include/linux/irqdesc.h
  62 @@ -61,6 +61,7 @@ struct irq_desc {
  63         unsigned int            irqs_unhandled;
  64         atomic_t                threads_handled;
  65         int                     threads_handled_last;
  66 +       u64                     random_ip;
  67         raw_spinlock_t          lock;
  68         struct cpumask          *percpu_enabled;
  69  #ifdef CONFIG_SMP
  70 diff --git a/include/linux/random.h b/include/linux/random.h
  71 index 9c29122..e7f2f86 100644
  72 --- a/include/linux/random.h
  73 +++ b/include/linux/random.h
  74 @@ -20,7 +20,7 @@ struct random_ready_callback {
  75  extern void add_device_randomness(const void *, unsigned int);
  76  extern void add_input_randomness(unsigned int type, unsigned int code,
  77                                  unsigned int value);
  78 -extern void add_interrupt_randomness(int irq, int irq_flags);
  79 +extern void add_interrupt_randomness(int irq, int irq_flags, __u64 ip);
  80
  81  extern void get_random_bytes(void *buf, int nbytes);
  82  extern int add_random_ready_callback(struct random_ready_callback *rdy);
  83 diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
  84 index 57bff78..6c65c92 100644
  85 --- a/kernel/irq/handle.c
  86 +++ b/kernel/irq/handle.c
  87 @@ -134,6 +134,8 @@ void __irq_wake_thread(struct irq_desc *desc, struct irqaction *action)
  88
  89  irqreturn_t handle_irq_event_percpu(struct irq_desc *desc)
  90  {
  91 +       struct pt_regs *regs = get_irq_regs();
  92 +       u64 ip = regs ? instruction_pointer(regs) : 0;
  93         irqreturn_t retval = IRQ_NONE;
  94         unsigned int flags = 0, irq = desc->irq_data.irq;
  95         struct irqaction *action = desc->action;
  96 @@ -176,7 +178,11 @@ irqreturn_t handle_irq_event_percpu(struct irq_desc *desc)
  97                 action = action->next;
  98         }
  99
 100 -       add_interrupt_randomness(irq, flags);
 101 +#ifdef CONFIG_PREEMPT_RT_FULL
 102 +       desc->random_ip = ip;
 103 +#else
 104 +       add_interrupt_randomness(irq, flags, ip);
 105 +#endif
 106
 107         if (!noirqdebug)
 108                 note_interrupt(desc, retval);
 109 diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
 110 index 5b1ad63..ba2a42a 100644
 111 --- a/kernel/irq/manage.c
 112 +++ b/kernel/irq/manage.c
 113 @@ -1045,6 +1045,12 @@ static int irq_thread(void *data)
 114                 if (action_ret == IRQ_WAKE_THREAD)
 115                         irq_wake_secondary(desc, action);
 116
 117 +#ifdef CONFIG_PREEMPT_RT_FULL
 118 +               migrate_disable();
 119 +               add_interrupt_randomness(action->irq, 0,
 120 +                                desc->random_ip ^ (unsigned long) action);
 121 +               migrate_enable();
 122 +#endif
 123                 wake_threads_waitq(desc);
 124         }
 125
 126 --
 127 2.7.4
 128