kernel/linux.git/drivers/char/random.c, branch linux-6.0.y

random: use arch_get_random*_early() in random_init()

2022-11-03T15:00:22+00:00

commit f5e4ec155d145002fd9840868453d785fab86d42 upstream. While reworking the archrandom handling, commit d349ab99eec7 ("random: handle archrandom with multiple longs") switched to the non-early archrandom helpers in random_init(), which broke initialization of the entropy pool from the arm64 random generator. Indeed at that point the arm64 CPU features, which verify that all CPUs have compatible capabilities, are not finalized so arch_get_random_seed_longs() is unsuccessful. Instead random_init() should use the _early functions, which check only the boot CPU on arm64. On other architectures the _early functions directly call the normal ones. Fixes: d349ab99eec7 ("random: handle archrandom with multiple longs") Cc: stable@vger.kernel.org Signed-off-by: Jean-Philippe Brucker Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman

random: schedule jitter credit for next jiffy, not in two jiffies

2022-10-21T10:39:01+00:00

[ Upstream commit 122733471384be8c23f019fbbd46bdf7be561dcd ] Counterintuitively, mod_timer(..., jiffies + 1) will cause the timer to fire not in the next jiffy, but in two jiffies. The way to cause the timer to fire in the next jiffy is with mod_timer(..., jiffies). Doing so then lets us bump the upper bound back up again. Fixes: 50ee7529ec45 ("random: try to actively add entropy rather than passively wait for it") Fixes: 829d680e82a9 ("random: cap jitter samples per bit to factor of HZ") Cc: Dominik Brodowski Cc: Sebastian Andrzej Siewior Cc: Sultan Alsawaf Signed-off-by: Jason A. Donenfeld Signed-off-by: Sasha Levin

random: use expired timer rather than wq for mixing fast pool

2022-10-15T06:02:57+00:00

commit 748bc4dd9e663f23448d8ad7e58c011a67ea1eca upstream. Previously, the fast pool was dumped into the main pool periodically in the fast pool's hard IRQ handler. This worked fine and there weren't problems with it, until RT came around. Since RT converts spinlocks into sleeping locks, problems cropped up. Rather than switching to raw spinlocks, the RT developers preferred we make the transformation from originally doing: do_some_stuff() spin_lock() do_some_other_stuff() spin_unlock() to doing: do_some_stuff() queue_work_on(some_other_stuff_worker) This is an ordinary pattern done all over the kernel. However, Sherry noticed a 10% performance regression in qperf TCP over a 40gbps InfiniBand card. Quoting her message: > MT27500 Family [ConnectX-3] cards: > Infiniband device 'mlx4_0' port 1 status: > default gid: fe80:0000:0000:0000:0010:e000:0178:9eb1 > base lid: 0x6 > sm lid: 0x1 > state: 4: ACTIVE > phys state: 5: LinkUp > rate: 40 Gb/sec (4X QDR) > link_layer: InfiniBand > > Cards are configured with IP addresses on private subnet for IPoIB > performance testing. > Regression identified in this bug is in TCP latency in this stack as reported > by qperf tcp_lat metric: > > We have one system listen as a qperf server: > [root@yourQperfServer ~]# qperf > > Have the other system connect to qperf server as a client (in this > case, it’s X7 server with Mellanox card): > [root@yourQperfClient ~]# numactl -m0 -N0 qperf 20.20.20.101 -v -uu -ub --time 60 --wait_server 20 -oo msg_size:4K:1024K:*2 tcp_lat Rather than incur the scheduling latency from queue_work_on, we can instead switch to running on the next timer tick, on the same core. This also batches things a bit more -- once per jiffy -- which is okay now that mix_interrupt_randomness() can credit multiple bits at once. Reported-by: Sherry Yang Tested-by: Paul Webb Cc: Sherry Yang Cc: Phillip Goerl Cc: Jack Vogel Cc: Nicky Veitch Cc: Colm Harrington Cc: Ramanan Govindarajan Cc: Sebastian Andrzej Siewior Cc: Dominik Brodowski Cc: Tejun Heo Cc: Sultan Alsawaf Cc: stable@vger.kernel.org Fixes: 58340f8e952b ("random: defer fast pool mixing to worker") Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman

random: avoid reading two cache lines on irq randomness

2022-10-15T06:02:57+00:00

commit 9ee0507e896b45af6d65408c77815800bce30008 upstream. In order to avoid reading and dirtying two cache lines on every IRQ, move the work_struct to the bottom of the fast_pool struct. add_ interrupt_randomness() always touches .pool and .count, which are currently split, because .mix pushes everything down. Instead, move .mix to the bottom, so that .pool and .count are always in the first cache line, since .mix is only accessed when the pool is full. Fixes: 58340f8e952b ("random: defer fast pool mixing to worker") Reviewed-by: Sebastian Andrzej Siewior Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman

random: clamp credited irq bits to maximum mixed

2022-10-15T06:02:55+00:00

commit e78a802a7b4febf53f2a92842f494b01062d85a8 upstream. Since the most that's mixed into the pool is sizeof(long)*2, don't credit more than that many bytes of entropy. Fixes: e3e33fc2ea7f ("random: do not use input pool from hard IRQs") Cc: stable@vger.kernel.org Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman

random: restore O_NONBLOCK support

2022-10-15T06:02:55+00:00

commit cd4f24ae9404fd31fc461066e57889be3b68641b upstream. Prior to 5.6, when /dev/random was opened with O_NONBLOCK, it would return -EAGAIN if there was no entropy. When the pools were unified in 5.6, this was lost. The post 5.6 behavior of blocking until the pool is initialized, and ignoring O_NONBLOCK in the process, went unnoticed, with no reports about the regression received for two and a half years. However, eventually this indeed did break somebody's userspace. So we restore the old behavior, by returning -EAGAIN if the pool is not initialized. Unlike the old /dev/random, this can only occur during early boot, after which it never blocks again. In order to make this O_NONBLOCK behavior consistent with other expectations, also respect users reading with preadv2(RWF_NOWAIT) and similar. Fixes: 30c08efec888 ("random: make /dev/random be almost like /dev/urandom") Reported-by: Guozihua Reported-by: Zhongguohua Cc: Al Viro Cc: Theodore Ts'o Cc: Andrew Lutomirski Cc: stable@vger.kernel.org Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman

Merge tag 'char-misc-6.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc

2022-08-04T18:05:48+00:00

Pull char / misc driver updates from Greg KH: "Here is the large set of char and misc and other driver subsystem changes for 6.0-rc1. Highlights include: - large set of IIO driver updates, additions, and cleanups - new habanalabs device support added (loads of register maps much like GPUs have) - soundwire driver updates - phy driver updates - slimbus driver updates - tiny virt driver fixes and updates - misc driver fixes and updates - interconnect driver updates - hwtracing driver updates - fpga driver updates - extcon driver updates - firmware driver updates - counter driver update - mhi driver fixes and updates - binder driver fixes and updates - speakup driver fixes All of these have been in linux-next for a while without any reported problems" * tag 'char-misc-6.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (634 commits) drivers: lkdtm: fix clang -Wformat warning char: remove VR41XX related char driver misc: Mark MICROCODE_MINOR unused spmi: trace: fix stack-out-of-bound access in SPMI tracing functions dt-bindings: iio: adc: Add compatible for MT8188 iio: light: isl29028: Fix the warning in isl29028_remove() iio: accel: sca3300: Extend the trigger buffer from 16 to 32 bytes iio: fix iio_format_avail_range() printing for none IIO_VAL_INT iio: adc: max1027: unlock on error path in max1027_read_single_value() iio: proximity: sx9324: add empty line in front of bullet list iio: magnetometer: hmc5843: Remove duplicate 'the' iio: magn: yas530: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() macros iio: magnetometer: ak8974: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() macros iio: light: veml6030: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() macros iio: light: vcnl4035: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() macros iio: light: vcnl4000: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() macros iio: light: tsl2591: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() iio: light: tsl2583: Use DEFINE_RUNTIME_DEV_PM_OPS and pm_ptr() iio: light: isl29028: Use DEFINE_RUNTIME_DEV_PM_OPS() and pm_ptr() iio: light: gp2ap002: Switch to DEFINE_RUNTIME_DEV_PM_OPS and pm_ptr() ...

random: correct spelling of "overwrites"

2022-07-29T23:13:02+00:00

It was missing an 'r'. Fixes: 186873c549df ("random: use simpler fast key erasure flow on per-cpu keys") Signed-off-by: Jason A. Donenfeld

random: handle archrandom with multiple longs

2022-07-25T11:26:14+00:00

The archrandom interface was originally designed for x86, which supplies RDRAND/RDSEED for receiving random words into registers, resulting in one function to generate an int and another to generate a long. However, other architectures don't follow this. On arm64, the SMCCC TRNG interface can return between one and three longs. On s390, the CPACF TRNG interface can return arbitrary amounts, with four longs having the same cost as one. On UML, the os_getrandom() interface can return arbitrary amounts. So change the api signature to take a "max_longs" parameter designating the maximum number of longs requested, and then return the number of longs generated. Since callers need to check this return value and loop anyway, each arch implementation does not bother implementing its own loop to try again to fill the maximum number of longs. Additionally, all existing callers pass in a constant max_longs parameter. Taken together, these two things mean that the codegen doesn't really change much for one-word-at-a-time platforms, while performance is greatly improved on platforms such as s390. Acked-by: Heiko Carstens Acked-by: Catalin Marinas Acked-by: Mark Rutland Acked-by: Michael Ellerman Acked-by: Borislav Petkov Signed-off-by: Jason A. Donenfeld

random: use try_cmpxchg in _credit_init_bits

2022-07-18T13:04:04+00:00

Use `!try_cmpxchg(ptr, &orig, new)` instead of `cmpxchg(ptr, orig, new) != orig` in _credit_init_bits. This has two benefits: - The x86 cmpxchg instruction returns success in the ZF flag, so this change saves a compare after cmpxchg, as well as a related move instruction in front of cmpxchg. - try_cmpxchg implicitly assigns the *ptr value to &orig when cmpxchg fails, enabling further code simplifications. This patch has no functional change. Signed-off-by: Uros Bizjak Signed-off-by: Jason A. Donenfeld