From 3995fb8aee32783d3386d82a5a6910a86c7bf38c Mon Sep 17 00:00:00 2001
From: Alex Auvolat <alex.auvolat@ens.fr>
Date: Sun, 8 Mar 2015 11:58:06 +0100
Subject: Add two entropy sources. Warning: prng is not secure in any way, I
 have no knowlege of such things.

---
 src/kernel/core/prng.c   | 10 +++++++---
 src/kernel/core/thread.c |  4 ++++
 src/kernel/core/worker.c |  3 +++
 3 files changed, 14 insertions(+), 3 deletions(-)

(limited to 'src/kernel/core')

diff --git a/src/kernel/core/prng.c b/src/kernel/core/prng.c
index d4307b6..dbffba5 100644
--- a/src/kernel/core/prng.c
+++ b/src/kernel/core/prng.c
@@ -1,4 +1,5 @@
 #include <prng.h>
+#include <thread.h>
 
 #define EPOOLSIZE 2048
 
@@ -10,11 +11,10 @@ static const uint32_t a = 16807;
 static const uint32_t m = 0x7FFFFFFF;
 
 uint16_t prng_word() {
-	if (++n == 100) {
+	if (++n >= 100) {
 		n = 0;
 		if (entropy_count) {
-			entropy_count--;
-			x += entropy[entropy_count];
+			x += entropy[--entropy_count];
 		}
 	}
 	x = (x * a) % m;
@@ -30,9 +30,13 @@ void prng_bytes(uint8_t* out, size_t nbytes) {
 }
 
 void prng_add_entropy(const uint8_t* ptr, size_t nbytes) {
+	int st = enter_critical(CL_NOINT);
+
 	while (nbytes-- && entropy_count < EPOOLSIZE - 1) {
 		entropy[entropy_count++] = *(ptr++);
 	}
+
+	exit_critical(st);
 }
 
 /* vim: set ts=4 sw=4 tw=0 noet :*/
diff --git a/src/kernel/core/thread.c b/src/kernel/core/thread.c
index 43b56a5..d59b71d 100644
--- a/src/kernel/core/thread.c
+++ b/src/kernel/core/thread.c
@@ -11,6 +11,7 @@
 #include <worker.h>
 #include <process.h>
 #include <freemem.h>
+#include <prng.h>
 
 void save_context_and_enter_scheduler(saved_context_t *ctx);
 void resume_context(saved_context_t *ctx);
@@ -124,6 +125,9 @@ void run_scheduler() {
 	current_thread = dequeue_thread();
 
 	if (current_thread != 0) {
+		thread_t *ptr = current_thread;
+		prng_add_entropy((uint8_t*)&ptr, sizeof(ptr));
+
 		set_kernel_stack(current_thread->stack_region->addr + current_thread->stack_region->size);
 		resume_context(&current_thread->ctx);
 	} else {
diff --git a/src/kernel/core/worker.c b/src/kernel/core/worker.c
index e367115..cb7bf34 100644
--- a/src/kernel/core/worker.c
+++ b/src/kernel/core/worker.c
@@ -2,6 +2,7 @@
 #include <btree.h>
 #include <mutex.h>
 #include <malloc.h>
+#include <prng.h>
 
 static uint64_t time = 0;
 static uint64_t next_task_time = UINT64_MAX;
@@ -58,6 +59,8 @@ void worker_thread(void* x) {
 		mutex_unlock(&tasks_mutex);
 		
 		if (t != 0) {
+			prng_add_entropy((uint8_t*)&t, sizeof(t));
+
 			// do task :-)
 			t->fun(t->data);
 			free(t);
-- 
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