The branch main has been updated by kevans:
URL:
https://cgit.FreeBSD.org/src/commit/?id=642701abc8357d2e6512b324956cfbcd6f25b482
commit 642701abc8357d2e6512b324956cfbcd6f25b482
Author: Kyle Evans <kev...@freebsd.org>
AuthorDate: 2022-02-03 16:05:06 +0000
Commit: Kyle Evans <kev...@freebsd.org>
CommitDate: 2022-02-03 16:05:06 +0000
kern: harvest entropy from callouts
74cf7cae4d22 ("softclock: Use dedicated ithreads for running callouts.")
switched callouts away from the swi infrastructure. It turns out that
this was a major source of entropy in early boot, which we've now lost.
As a result, first boot on hardware without a 'fast' entropy source
would block waiting for fortuna to be seeded with little hope of
progressing without manual intervention.
Let's resolve it by explicitly harvesting entropy in callout_process()
if we've handled any callouts. cc/curthread/now seem to be reasonable
sources of entropy, so use those.
Discussed with: jhb (also proposed initial patch)
Reported by: many
Reviewed by: cem, markm (both csprng)
Differential Revision: https://reviews.freebsd.org/D34150
---
sys/dev/random/fenestrasX/fx_pool.c | 3 +++
sys/dev/random/random_harvestq.c | 3 ++-
sys/kern/kern_timeout.c | 11 +++++++++++
sys/sys/random.h | 3 ++-
4 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/sys/dev/random/fenestrasX/fx_pool.c
b/sys/dev/random/fenestrasX/fx_pool.c
index b6cc0dad349d..f2fc15874b67 100644
--- a/sys/dev/random/fenestrasX/fx_pool.c
+++ b/sys/dev/random/fenestrasX/fx_pool.c
@@ -164,6 +164,9 @@ static const struct fxrng_ent_char {
[RANDOM_UMA] = {
.entc_cls = &fxrng_lo_push,
},
+ [RANDOM_CALLOUT] = {
+ .entc_cls = &fxrng_lo_push,
+ },
[RANDOM_PURE_OCTEON] = {
.entc_cls = &fxrng_hi_push, /* Could be made pull. */
},
diff --git a/sys/dev/random/random_harvestq.c b/sys/dev/random/random_harvestq.c
index 46c069126949..aae8ec9172d7 100644
--- a/sys/dev/random/random_harvestq.c
+++ b/sys/dev/random/random_harvestq.c
@@ -349,7 +349,8 @@ static const char *random_source_descr[ENTROPYSOURCE] = {
[RANDOM_INTERRUPT] = "INTERRUPT",
[RANDOM_SWI] = "SWI",
[RANDOM_FS_ATIME] = "FS_ATIME",
- [RANDOM_UMA] = "UMA", /* ENVIRONMENTAL_END */
+ [RANDOM_UMA] = "UMA",
+ [RANDOM_CALLOUT] = "CALLOUT", /* ENVIRONMENTAL_END */
[RANDOM_PURE_OCTEON] = "PURE_OCTEON", /* PURE_START */
[RANDOM_PURE_SAFE] = "PURE_SAFE",
[RANDOM_PURE_GLXSB] = "PURE_GLXSB",
diff --git a/sys/kern/kern_timeout.c b/sys/kern/kern_timeout.c
index d0fb19661fa4..bc7b50e5ff8f 100644
--- a/sys/kern/kern_timeout.c
+++ b/sys/kern/kern_timeout.c
@@ -57,6 +57,7 @@ __FBSDID("$FreeBSD$");
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
+#include <sys/random.h>
#include <sys/sched.h>
#include <sys/sdt.h>
#include <sys/sleepqueue.h>
@@ -430,6 +431,11 @@ callout_get_bucket(sbintime_t sbt)
void
callout_process(sbintime_t now)
{
+ struct callout_entropy {
+ struct callout_cpu *cc;
+ struct thread *td;
+ sbintime_t now;
+ } entropy;
struct callout *tmp, *tmpn;
struct callout_cpu *cc;
struct callout_list *sc;
@@ -545,6 +551,11 @@ next:
avg_lockcalls_dir += (lockcalls_dir * 1000 - avg_lockcalls_dir) >> 8;
#endif
if (!TAILQ_EMPTY(&cc->cc_expireq)) {
+ entropy.cc = cc;
+ entropy.td = curthread;
+ entropy.now = now;
+ random_harvest_queue(&entropy, sizeof(entropy), RANDOM_CALLOUT);
+
td = cc->cc_thread;
if (TD_AWAITING_INTR(td)) {
thread_lock_block_wait(td);
diff --git a/sys/sys/random.h b/sys/sys/random.h
index cfcf4b30e698..6f4f90c9de98 100644
--- a/sys/sys/random.h
+++ b/sys/sys/random.h
@@ -86,7 +86,8 @@ enum random_entropy_source {
RANDOM_SWI,
RANDOM_FS_ATIME,
RANDOM_UMA, /* Special!! UMA/SLAB Allocator */
- RANDOM_ENVIRONMENTAL_END = RANDOM_UMA,
+ RANDOM_CALLOUT,
+ RANDOM_ENVIRONMENTAL_END = RANDOM_CALLOUT,
/* Fast hardware random-number sources from here on. */
RANDOM_PURE_START,
RANDOM_PURE_OCTEON = RANDOM_PURE_START,
