Jason A. Donenfeld
a7d04ca9da
timekeeping: Add raw clock fallback for random_get_entropy()
...
commit 1366992e16bddd5e2d9a561687f367f9f802e2e4 upstream.
The addition of random_get_entropy_fallback() provides access to
whichever time source has the highest frequency, which is useful for
gathering entropy on platforms without available cycle counters. It's
not necessarily as good as being able to quickly access a cycle counter
that the CPU has, but it's still something, even when it falls back to
being jiffies-based.
In the event that a given arch does not define get_cycles(), falling
back to the get_cycles() default implementation that returns 0 is really
not the best we can do. Instead, at least calling
random_get_entropy_fallback() would be preferable, because that always
needs to return _something_, even falling back to jiffies eventually.
It's not as though random_get_entropy_fallback() is super high precision
or guaranteed to be entropic, but basically anything that's not zero all
the time is better than returning zero all the time.
Finally, since random_get_entropy_fallback() is used during extremely
early boot when randomizing freelists in mm_init(), it can be called
before timekeeping has been initialized. In that case there really is
nothing we can do; jiffies hasn't even started ticking yet. So just give
up and return 0.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-06-22 14:11:15 +02:00
..
bpf
bpf: Fix incorrect memory charge cost calculation in stack_map_alloc()
2022-06-22 14:11:02 +02:00
cgroup
cgroup/cpuset: Remove cpus_allowed/mems_allowed setup in cpuset_init_smp()
2022-05-18 09:47:27 +02:00
configs
debug
lockdown: also lock down previous kgdb use
2022-06-06 08:33:48 +02:00
dma
dma-debug: change allocation mode from GFP_NOWAIT to GFP_ATIOMIC
2022-06-14 18:11:28 +02:00
events
perf: Fix sys_perf_event_open() race against self
2022-05-25 09:14:34 +02:00
gcov
gcov: re-fix clang-11+ support
2021-04-14 08:24:10 +02:00
irq
random: remove unused irq_flags argument from add_interrupt_randomness()
2022-06-22 14:11:06 +02:00
livepatch
locking
locking/lockdep: Avoid RCU-induced noinstr fail
2021-11-17 09:48:28 +01:00
power
PM: suspend: fix return value of __setup handler
2022-04-15 14:18:05 +02:00
printk
printk: fix return value of printk.devkmsg __setup handler
2022-04-15 14:18:08 +02:00
rcu
rcu: Don't deboost before reporting expedited quiescent state
2022-03-28 08:46:48 +02:00
sched
sched/fair: Fix cfs_rq_clock_pelt() for throttled cfs_rq
2022-06-14 18:11:33 +02:00
time
timekeeping: Add raw clock fallback for random_get_entropy()
2022-06-22 14:11:15 +02:00
trace
tracing: Avoid adding tracer option before update_tracer_options
2022-06-14 18:11:56 +02:00
.gitignore
kbuild: update config_data.gz only when the content of .config is changed
2021-05-11 14:04:16 +02:00
acct.c
async.c
Revert "module, async: async_synchronize_full() on module init iff async is used"
2022-02-23 11:59:56 +01:00
audit.c
audit: improve audit queue handling when "audit=1" on cmdline
2022-02-08 18:24:26 +01:00
audit.h
audit: log AUDIT_TIME_* records only from rules
2022-04-15 14:18:04 +02:00
audit_fsnotify.c
audit_tree.c
audit: move put_tree() to avoid trim_trees refcount underflow and UAF
2021-09-03 10:08:16 +02:00
audit_watch.c
auditfilter.c
auditsc.c
audit: log AUDIT_TIME_* records only from rules
2022-04-15 14:18:04 +02:00
backtracetest.c
bounds.c
capability.c
compat.c
configs.c
context_tracking.c
cpu.c
random: clear fast pool, crng, and batches in cpuhp bring up
2022-06-22 14:11:12 +02:00
cpu_pm.c
crash_core.c
crash_dump.c
cred.c
delayacct.c
dma.c
exec_domain.c
exit.c
don't dump the threads that had been already exiting when zapped.
2020-11-18 19:20:31 +01:00
extable.c
fail_function.c
fail_function: Remove a redundant mutex unlock
2020-11-24 13:29:18 +01:00
fork.c
copy_process(): Move fd_install() out of sighand->siglock critical section
2022-02-23 12:00:00 +01:00
freezer.c
futex.c
mm, futex: fix shared futex pgoff on shmem huge page
2021-06-30 08:47:55 -04:00
gen_kheaders.sh
groups.c
hung_task.c
iomem.c
irq_work.c
jump_label.c
kallsyms.c
kcmp.c
exec: Transform exec_update_mutex into a rw_semaphore
2021-01-09 13:44:55 +01:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kcov.c
kexec.c
kexec_core.c
kernel: kexec: remove the lock operation of system_transition_mutex
2021-02-03 23:25:56 +01:00
kexec_elf.c
kexec_file.c
kernel: kexec_file: fix error return code of kexec_calculate_store_digests()
2021-05-19 10:08:28 +02:00
kexec_internal.h
kheaders.c
kmod.c
kprobes.c
kprobes: Limit max data_size of the kretprobe instances
2021-12-08 09:01:10 +01:00
ksysfs.c
kthread.c
kthread: Fix PF_KTHREAD vs to_kthread() race
2021-09-12 08:56:39 +02:00
latencytop.c
Makefile
kbuild: update config_data.gz only when the content of .config is changed
2021-05-11 14:04:16 +02:00
module-internal.h
module.c
module/ftrace: handle patchable-function-entry
2022-02-23 11:59:56 +01:00
module_signature.c
module: harden ELF info handling
2021-04-07 14:47:38 +02:00
module_signing.c
module: harden ELF info handling
2021-04-07 14:47:38 +02:00
notifier.c
nsproxy.c
padata.c
panic.c
params.c
pid.c
pid_namespace.c
memcg: enable accounting for pids in nested pid namespaces
2021-09-22 12:26:37 +02:00
profile.c
profiling: fix shift-out-of-bounds bugs
2021-09-26 14:07:09 +02:00
ptrace.c
ptrace: Reimplement PTRACE_KILL by always sending SIGKILL
2022-06-14 18:11:24 +02:00
range.c
reboot.c
reboot: fix overflow parsing reboot cpu number
2020-11-18 19:20:30 +01:00
relay.c
resource.c
rseq.c
seccomp.c
seccomp: Invalidate seccomp mode to catch death failures
2022-02-16 12:52:53 +01:00
signal.c
signal: Remove the bogus sigkill_pending in ptrace_stop
2021-11-17 09:48:24 +01:00
smp.c
smp: Fix offline cpu check in flush_smp_call_function_queue()
2022-04-20 09:19:39 +02:00
smpboot.c
kthread: Extract KTHREAD_IS_PER_CPU
2021-02-07 15:35:49 +01:00
smpboot.h
softirq.c
stackleak.c
stacktrace.c
stop_machine.c
sys.c
prctl: allow to setup brk for et_dyn executables
2021-09-26 14:07:08 +02:00
sys_ni.c
sysctl-test.c
sysctl.c
x86/speculation: Include unprivileged eBPF status in Spectre v2 mitigation reporting
2022-03-11 11:22:37 +01:00
sysctl_binary.c
task_work.c
taskstats.c
test_kprobes.c
torture.c
tracepoint.c
tracepoint: Add tracepoint_probe_register_may_exist() for BPF tracing
2021-07-14 16:53:08 +02:00
tsacct.c
taskstats: Cleanup the use of task->exit_code
2022-02-23 11:59:57 +01:00
ucount.c
uid16.c
uid16.h
umh.c
usermodehelper: reset umask to default before executing user process
2020-10-14 10:32:58 +02:00
up.c
smp: Fix smp_call_function_single_async prototype
2021-05-14 09:44:33 +02:00
user-return-notifier.c
user.c
user_namespace.c
utsname.c
utsname_sysctl.c
watchdog.c
watchdog_hld.c
workqueue.c
workqueue: Fix unbind_workers() VS wq_worker_running() race
2022-01-16 09:15:38 +01:00
workqueue_internal.h