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Date: Tue, 25 Jul 2023 02:56:27 +0800
From: kernel test robot <lkp@...el.com>
To: "Jason A. Donenfeld" <zx2c4@...nel.org>
Cc: oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: drivers/char/random.c:1329:1: warning: the frame size of 1360 bytes
is larger than 1024 bytes
Hi Jason,
First bad commit (maybe != root cause):
tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 20ea1e7d13c1b544fe67c4a8dc3943bb1ab33e6f
commit: 1c21fe00eda76e4081535c739cf9f4bbb5dcb0ce random: spread out jitter callback to different CPUs
date: 8 months ago
config: x86_64-intel-next-customedconfig-dcg_x86_64_defconfig (https://download.01.org/0day-ci/archive/20230725/202307250244.WRnC5csB-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce: (https://download.01.org/0day-ci/archive/20230725/202307250244.WRnC5csB-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202307250244.WRnC5csB-lkp@intel.com/
All warnings (new ones prefixed by >>):
drivers/char/random.c: In function 'try_to_generate_entropy':
>> drivers/char/random.c:1329:1: warning: the frame size of 1360 bytes is larger than 1024 bytes [-Wframe-larger-than=]
1329 | }
| ^
vim +1329 drivers/char/random.c
50ee7529ec4500 Linus Torvalds 2019-09-28 1258
50ee7529ec4500 Linus Torvalds 2019-09-28 1259 /*
0e42d14be23f4c Jason A. Donenfeld 2022-11-29 1260 * If we have an actual cycle counter, see if we can generate enough entropy
0e42d14be23f4c Jason A. Donenfeld 2022-11-29 1261 * with timing noise.
50ee7529ec4500 Linus Torvalds 2019-09-28 1262 */
560181c27b5825 Jason A. Donenfeld 2022-05-13 1263 static void __cold try_to_generate_entropy(void)
50ee7529ec4500 Linus Torvalds 2019-09-28 1264 {
122733471384be Jason A. Donenfeld 2022-10-01 1265 enum { NUM_TRIAL_SAMPLES = 8192, MAX_SAMPLES_PER_BIT = HZ / 15 };
78c768e619fbd5 Jason A. Donenfeld 2022-04-22 1266 struct entropy_timer_state stack;
78c768e619fbd5 Jason A. Donenfeld 2022-04-22 1267 unsigned int i, num_different = 0;
78c768e619fbd5 Jason A. Donenfeld 2022-04-22 1268 unsigned long last = random_get_entropy();
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1269 int cpu = -1;
50ee7529ec4500 Linus Torvalds 2019-09-28 1270
78c768e619fbd5 Jason A. Donenfeld 2022-04-22 1271 for (i = 0; i < NUM_TRIAL_SAMPLES - 1; ++i) {
4b758eda851eb9 Jason A. Donenfeld 2022-04-12 1272 stack.entropy = random_get_entropy();
78c768e619fbd5 Jason A. Donenfeld 2022-04-22 1273 if (stack.entropy != last)
78c768e619fbd5 Jason A. Donenfeld 2022-04-22 1274 ++num_different;
78c768e619fbd5 Jason A. Donenfeld 2022-04-22 1275 last = stack.entropy;
78c768e619fbd5 Jason A. Donenfeld 2022-04-22 1276 }
78c768e619fbd5 Jason A. Donenfeld 2022-04-22 1277 stack.samples_per_bit = DIV_ROUND_UP(NUM_TRIAL_SAMPLES, num_different + 1);
78c768e619fbd5 Jason A. Donenfeld 2022-04-22 1278 if (stack.samples_per_bit > MAX_SAMPLES_PER_BIT)
50ee7529ec4500 Linus Torvalds 2019-09-28 1279 return;
50ee7529ec4500 Linus Torvalds 2019-09-28 1280
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1281 atomic_set(&stack.samples, 0);
50ee7529ec4500 Linus Torvalds 2019-09-28 1282 timer_setup_on_stack(&stack.timer, entropy_timer, 0);
3e504d2026eb6c Jason A. Donenfeld 2022-03-08 1283 while (!crng_ready() && !signal_pending(current)) {
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1284 /*
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1285 * Check !timer_pending() and then ensure that any previous callback has finished
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1286 * executing by checking try_to_del_timer_sync(), before queueing the next one.
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1287 */
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1288 if (!timer_pending(&stack.timer) && try_to_del_timer_sync(&stack.timer) >= 0) {
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1289 struct cpumask timer_cpus;
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1290 unsigned int num_cpus;
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1291
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1292 /*
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1293 * Preemption must be disabled here, both to read the current CPU number
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1294 * and to avoid scheduling a timer on a dead CPU.
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1295 */
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1296 preempt_disable();
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1297
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1298 /* Only schedule callbacks on timer CPUs that are online. */
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1299 cpumask_and(&timer_cpus, housekeeping_cpumask(HK_TYPE_TIMER), cpu_online_mask);
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1300 num_cpus = cpumask_weight(&timer_cpus);
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1301 /* In very bizarre case of misconfiguration, fallback to all online. */
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1302 if (unlikely(num_cpus == 0)) {
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1303 timer_cpus = *cpu_online_mask;
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1304 num_cpus = cpumask_weight(&timer_cpus);
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1305 }
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1306
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1307 /* Basic CPU round-robin, which avoids the current CPU. */
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1308 do {
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1309 cpu = cpumask_next(cpu, &timer_cpus);
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1310 if (cpu == nr_cpumask_bits)
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1311 cpu = cpumask_first(&timer_cpus);
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1312 } while (cpu == smp_processor_id() && num_cpus > 1);
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1313
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1314 /* Expiring the timer at `jiffies` means it's the next tick. */
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1315 stack.timer.expires = jiffies;
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1316
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1317 add_timer_on(&stack.timer, cpu);
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1318
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1319 preempt_enable();
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1320 }
4b758eda851eb9 Jason A. Donenfeld 2022-04-12 1321 mix_pool_bytes(&stack.entropy, sizeof(stack.entropy));
50ee7529ec4500 Linus Torvalds 2019-09-28 1322 schedule();
4b758eda851eb9 Jason A. Donenfeld 2022-04-12 1323 stack.entropy = random_get_entropy();
50ee7529ec4500 Linus Torvalds 2019-09-28 1324 }
1c21fe00eda76e Jason A. Donenfeld 2022-10-01 1325 mix_pool_bytes(&stack.entropy, sizeof(stack.entropy));
50ee7529ec4500 Linus Torvalds 2019-09-28 1326
50ee7529ec4500 Linus Torvalds 2019-09-28 1327 del_timer_sync(&stack.timer);
50ee7529ec4500 Linus Torvalds 2019-09-28 1328 destroy_timer_on_stack(&stack.timer);
50ee7529ec4500 Linus Torvalds 2019-09-28 @1329 }
50ee7529ec4500 Linus Torvalds 2019-09-28 1330
:::::: The code at line 1329 was first introduced by commit
:::::: 50ee7529ec4500c88f8664560770a7a1b65db72b random: try to actively add entropy rather than passively wait for it
:::::: TO: Linus Torvalds <torvalds@...ux-foundation.org>
:::::: CC: Linus Torvalds <torvalds@...ux-foundation.org>
--
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