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Commit 419800cf authored by Jason A. Donenfeld's avatar Jason A. Donenfeld Committed by Greg Kroah-Hartman
Browse files

random: make random_get_entropy() return an unsigned long 



commit b0c3e796f24b588b862b61ce235d3c9417dc8983 upstream.

Some implementations were returning type `unsigned long`, while others
that fell back to get_cycles() were implicitly returning a `cycles_t` or
an untyped constant int literal. That makes for weird and confusing
code, and basically all code in the kernel already handled it like it
was an `unsigned long`. I recently tried to handle it as the largest
type it could be, a `cycles_t`, but doing so doesn't really help with
much.

Instead let's just make random_get_entropy() return an unsigned long all
the time. This also matches the commonly used `arch_get_random_long()`
function, so now RDRAND and RDTSC return the same sized integer, which
means one can fallback to the other more gracefully.

Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Theodore Ts'o <tytso@mit.edu>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c98e0cfe

drivers/char/random.c

+7 −13
Original line number Diff line number Diff line
@@ -1010,7 +1010,7 @@ int __init rand_initialize(void) 
 */

void add_device_randomness(const void *buf, size_t size)

{

	cycles_t cycles = random_get_entropy();

	unsigned long cycles = random_get_entropy();

	unsigned long flags, now = jiffies;



	if (crng_init == 0 && size)
@@ -1041,8 +1041,7 @@ struct timer_rand_state { 
 */

static void add_timer_randomness(struct timer_rand_state *state, unsigned int num)

{

	cycles_t cycles = random_get_entropy();

	unsigned long flags, now = jiffies;

	unsigned long cycles = random_get_entropy(), now = jiffies, flags;

	long delta, delta2, delta3;



	spin_lock_irqsave(&input_pool.lock, flags);
@@ -1297,8 +1296,7 @@ static void mix_interrupt_randomness(struct work_struct *work) 
void add_interrupt_randomness(int irq)

{

	enum { MIX_INFLIGHT = 1U << 31 };

	cycles_t cycles = random_get_entropy();

	unsigned long now = jiffies;

	unsigned long cycles = random_get_entropy(), now = jiffies;

	struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness);

	struct pt_regs *regs = get_irq_regs();

	unsigned int new_count;
@@ -1311,16 +1309,12 @@ void add_interrupt_randomness(int irq) 
	if (cycles == 0)

		cycles = get_reg(fast_pool, regs);



	if (sizeof(cycles) == 8)

	if (sizeof(unsigned long) == 8) {

		irq_data.u64[0] = cycles ^ rol64(now, 32) ^ irq;

	else {

		irq_data.u64[1] = regs ? instruction_pointer(regs) : _RET_IP_;

	} else {

		irq_data.u32[0] = cycles ^ irq;

		irq_data.u32[1] = now;

	}



	if (sizeof(unsigned long) == 8)

		irq_data.u64[1] = regs ? instruction_pointer(regs) : _RET_IP_;

	else {

		irq_data.u32[2] = regs ? instruction_pointer(regs) : _RET_IP_;

		irq_data.u32[3] = get_reg(fast_pool, regs);

	}
@@ -1367,7 +1361,7 @@ static void entropy_timer(struct timer_list *t) 
static void try_to_generate_entropy(void)

{

	struct {

		cycles_t cycles;

		unsigned long cycles;

		struct timer_list timer;

	} stack;

include/linux/timex.h

+1 −1
Original line number Diff line number Diff line
@@ -75,7 +75,7 @@ 
 * By default we use get_cycles() for this purpose, but individual

 * architectures may override this in their asm/timex.h header file.

 */

#define random_get_entropy()	get_cycles()

#define random_get_entropy()	((unsigned long)get_cycles())

#endif



/*