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Merge tag 'random-6.0-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random
Pull random number generator updates from Jason Donenfeld:
"Though there's been a decent amount of RNG-related development during
this last cycle, not all of it is coming through this tree, as this
cycle saw a shift toward tackling early boot time seeding issues,
which took place in other trees as well.
Here's a summary of the various patches:
- The CONFIG_ARCH_RANDOM .config option and the "nordrand" boot
option have been removed, as they overlapped with the more widely
supported and more sensible options, CONFIG_RANDOM_TRUST_CPU and
"random.trust_cpu". This change allowed simplifying a bit of arch
code.
- x86's RDRAND boot time test has been made a bit more robust, with
RDRAND disabled if it's clearly producing bogus results. This would
be a tip.git commit, technically, but I took it through random.git
to avoid a large merge conflict.
- The RNG has long since mixed in a timestamp very early in boot, on
the premise that a computer that does the same things, but does so
starting at different points in wall time, could be made to still
produce a different RNG state. Unfortunately, the clock isn't set
early in boot on all systems, so now we mix in that timestamp when
the time is actually set.
- User Mode Linux now uses the host OS's getrandom() syscall to
generate a bootloader RNG seed and later on treats getrandom() as
the platform's RDRAND-like faculty.
- The arch_get_random_{seed_,}_long() family of functions is now
arch_get_random_{seed_,}_longs(), which enables certain platforms,
such as s390, to exploit considerable performance advantages from
requesting multiple CPU random numbers at once, while at the same
time compiling down to the same code as before on platforms like
x86.
- A small cleanup changing a cmpxchg() into a try_cmpxchg(), from
Uros.
- A comment spelling fix"
More info about other random number changes that come in through various
architecture trees in the full commentary in the pull request:
https://lore.kernel.org/all/20220731232428.2219258-1-Jason@zx2c4.com/
* tag 'random-6.0-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random:
random: correct spelling of "overwrites"
random: handle archrandom with multiple longs
um: seed rng using host OS rng
random: use try_cmpxchg in _credit_init_bits
timekeeping: contribute wall clock to rng on time change
x86/rdrand: Remove "nordrand" flag in favor of "random.trust_cpu"
random: remove CONFIG_ARCH_RANDOM
39 lines
947 B
C
39 lines
947 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Kernel interface for the s390 arch_random_* functions
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*
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* Copyright IBM Corp. 2017, 2022
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*
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* Author: Harald Freudenberger <freude@de.ibm.com>
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*
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*/
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#ifndef _ASM_S390_ARCHRANDOM_H
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#define _ASM_S390_ARCHRANDOM_H
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#include <linux/static_key.h>
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#include <linux/preempt.h>
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#include <linux/atomic.h>
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#include <asm/cpacf.h>
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DECLARE_STATIC_KEY_FALSE(s390_arch_random_available);
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extern atomic64_t s390_arch_random_counter;
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static inline size_t __must_check arch_get_random_longs(unsigned long *v, size_t max_longs)
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{
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return 0;
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}
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static inline size_t __must_check arch_get_random_seed_longs(unsigned long *v, size_t max_longs)
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{
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if (static_branch_likely(&s390_arch_random_available) &&
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in_task()) {
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cpacf_trng(NULL, 0, (u8 *)v, max_longs * sizeof(*v));
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atomic64_add(max_longs * sizeof(*v), &s390_arch_random_counter);
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return max_longs;
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}
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return 0;
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}
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#endif /* _ASM_S390_ARCHRANDOM_H */
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