diff options
| author | Vadim Sukhomlinov <sukhomlinov@google.com> | 2021-12-29 11:32:48 -0800 |
|---|---|---|
| committer | Commit Bot <commit-bot@chromium.org> | 2021-12-30 04:02:09 +0000 |
| commit | ae6151720c4f1e4901c957128dbc7e59bbcd220b (patch) | |
| tree | 5c545aaa59eb263ec1e594af9509bddcfd235912 | |
| parent | 914a20f4b8640abf32691a4db7d7160303e2f419 (diff) | |
| download | chrome-ec-ae6151720c4f1e4901c957128dbc7e59bbcd220b.tar.gz | |
cr50: update TRNG resets
It seems we have relatively high number of devices with slow TRNG,
mostly Octopus and Grunt platforms. To mitigate potential issues
increased TRNG reset counts from 8 to 16 to give a chance to recover,
and updated recording of TRNG stall to record only first occurrence
of stall per 32-bit.
BUG=b:211648605
TEST=test/tpm_test/nist_entropy.sh - loads TRNG
Signed-off-by: Vadim Sukhomlinov <sukhomlinov@google.com>
Change-Id: I11d0e9ca2955894b2ed95dbfbf71ad8ff153c53e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3358466
Reviewed-by: Vadim Sukhomlinov <sukhomlinov@chromium.org>
Tested-by: Vadim Sukhomlinov <sukhomlinov@chromium.org>
Reviewed-by: Andrey Pronin <apronin@chromium.org>
Commit-Queue: Vadim Sukhomlinov <sukhomlinov@chromium.org>
| -rw-r--r-- | board/cr50/dcrypto/trng.c | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/board/cr50/dcrypto/trng.c b/board/cr50/dcrypto/trng.c index 31ea4e6ba3..53b448499b 100644 --- a/board/cr50/dcrypto/trng.c +++ b/board/cr50/dcrypto/trng.c @@ -43,7 +43,7 @@ static volatile struct trng_reg *reg_trng = (void *)(GC_TRNG_BASE_ADDR); /** * Number of attempts to reset TRNG after stall is detected. */ -#define TRNG_RESET_COUNT 8 +#define TRNG_RESET_COUNT 16 void fips_init_trng(void) { @@ -127,13 +127,19 @@ uint64_t read_rand(void) empty_count > TRNG_EMPTY_COUNT) { /* TRNG timed out, restart */ reg_trng->stop_work = 1; -#ifdef CONFIG_FLASH_LOG - fips_vtable->flash_log_add_event(FE_LOG_TRNG_STALL, 0, - NULL); -#endif - reg_trng->go_event = 1; empty_count = 0; reset_count++; + reg_trng->go_event = 1; +#ifdef CONFIG_FLASH_LOG + /** + * Log stall only first time. Placing it after TRNG + * go_event increase a chance to get random in case + * of slow TRNG. + */ + if (reset_count == 1) + fips_vtable->flash_log_add_event( + FE_LOG_TRNG_STALL, 0, NULL); +#endif } empty_count++; } |