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From 39bd47e442b4654f824987ebaff05ce1dfaa1af0 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 21 Aug 2012 20:38:50 +0200
Subject: [PATCH 149/191] 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>
---
arch/x86/kernel/cpu/mshyperv.c | 3 ++-
drivers/char/random.c | 11 +++++------
drivers/hv/hyperv_vmbus.h | 1 +
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 ++++++
8 files changed, 27 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index e88bc296afca..73a2494a0b2e 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -85,11 +85,12 @@ EXPORT_SYMBOL_GPL(hv_remove_vmbus_irq);
DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_stimer0)
{
struct pt_regs *old_regs = set_irq_regs(regs);
+ u64 ip = regs ? instruction_pointer(regs) : 0;
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();
set_irq_regs(old_regs);
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 0fe9e200e4c8..da0a1ef9615c 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1252,26 +1252,25 @@ 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;
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/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 9416e09ebd58..4a5767a15544 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -18,6 +18,7 @@
#include <linux/atomic.h>
#include <linux/hyperv.h>
#include <linux/interrupt.h>
+#include <linux/irq.h>
#include "hv_trace.h"
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 806950bc3c1d..e0afa5031cc4 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>
@@ -1337,6 +1338,8 @@ 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))
@@ -1381,7 +1384,7 @@ 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 891b323266df..45d8bda8fd53 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -68,6 +68,7 @@ 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 f45b8be3e3c4..0e41d0527809 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -35,7 +35,7 @@ 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 762a928e18f9..7929fcdb7817 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -192,10 +192,16 @@ 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 ac2c57429750..f4d18858d079 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1247,6 +1247,12 @@ static int irq_thread(void *data)
if (action_ret == IRQ_WAKE_THREAD)
irq_wake_secondary(desc, action);
+ if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
+ migrate_disable();
+ add_interrupt_randomness(action->irq, 0,
+ desc->random_ip ^ (unsigned long) action);
+ migrate_enable();
+ }
wake_threads_waitq(desc);
}
--
2.19.1
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