From: "Jason A. Donenfeld" Jason@zx2c4.com
stable inclusion from stable-v5.10.119 commit a1b5c849d855c97f75375c564321961ad18b8f46 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5L6BB
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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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: Thomas Gleixner tglx@linutronix.de Signed-off-by: Jason A. Donenfeld Jason@zx2c4.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Acked-by: Xie XiuQi xiexiuqi@huawei.com --- drivers/char/random.c | 20 +++++++------------- include/linux/timex.h | 2 +- 2 files changed, 8 insertions(+), 14 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c index 4ec60f4cb086..8b09d608c802 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1015,7 +1015,7 @@ 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) @@ -1046,8 +1046,7 @@ 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); @@ -1302,8 +1301,7 @@ 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; @@ -1316,16 +1314,12 @@ 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); } @@ -1372,7 +1366,7 @@ 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;
diff --git a/include/linux/timex.h b/include/linux/timex.h index ce0859763670..e5154378076d 100644 --- a/include/linux/timex.h +++ b/include/linux/timex.h @@ -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
/*