Subject: random: Make it work on rt
From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 21 Aug 2012 20:38:50 +0200
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
Git-commit: da77ceac3d20f27310a07a7c346a4ee6b40d6c28
Patch-mainline: Queued in subsystem maintainer repository
References: SLE Realtime Extension
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>
Signed-off-by: Daniel Wagner <dwagner@suse.de>
---
arch/x86/kernel/cpu/mshyperv.c | 3 ++-
drivers/char/random.c | 11 +++++------
drivers/hv/vmbus_drv.c | 5 ++++-
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(-)
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 5b30edd03616..3d5f7a6b7d55 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -82,12 +82,13 @@ EXPORT_SYMBOL_GPL(hv_remove_vmbus_irq);
__visible void __irq_entry hv_stimer0_vector_handler(struct pt_regs *regs)
{
struct pt_regs *old_regs = set_irq_regs(regs);
+ u64 ip = regs ? instruction_pointer(regs) : 0;
entering_irq();
inc_irq_stat(hyperv_stimer0_count);
if (hv_stimer0_handler)
hv_stimer0_handler();
- add_interrupt_randomness(HYPERV_STIMER0_VECTOR, 0);
+ add_interrupt_randomness(HYPERV_STIMER0_VECTOR, 0, ip);
ack_APIC_irq();
exiting_irq();
diff --git a/drivers/char/random.c b/drivers/char/random.c
index e270b25459ae..05acd9aaa0f7 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1321,28 +1321,27 @@ 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 4fad3e6745e5..a24656620b93 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -22,6 +22,7 @@
#include <linux/clockchips.h>
#include <linux/cpu.h>
#include <linux/sched/task_stack.h>
+#include <linux/irq.h>
#include <linux/delay.h>
#include <linux/notifier.h>
@@ -1307,6 +1308,8 @@ 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))
@@ -1351,7 +1354,7 @@ static void vmbus_isr(void)
tasklet_schedule(&hv_cpu->msg_dpc);
}
- add_interrupt_randomness(hv_get_vector(), 0);
+ add_interrupt_randomness(hv_get_vector(), 0, ip);
}
/*
diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index d6e2ab538ef2..1e7fc375c36d 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -72,6 +72,7 @@ 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 5b3ec7d2791f..15b9fed04dba 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -33,7 +33,7 @@ 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 a4ace611f47f..3306fabed221 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -185,10 +185,16 @@ 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
+ 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 4d123e046130..870997b2e31a 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1138,6 +1138,12 @@ static int irq_thread(void *data)
if (action_ret == IRQ_WAKE_THREAD)
irq_wake_secondary(desc, action);
+#ifdef CONFIG_PREEMPT_RT
+ migrate_disable();
+ add_interrupt_randomness(action->irq, 0,
+ desc->random_ip ^ (unsigned long) action);
+ migrate_enable();
+#endif
wake_threads_waitq(desc);
}
--
2.26.2