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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-24 08:46:03 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-24 08:46:03 -0700 |
| commit | cf9610f9116d55c5a66ef9f1faecacabd93a9322 (patch) | |
| tree | 757a3d280760c654767631cab5ad8af2d86d1848 /lib/math/prime_numbers.c | |
| download | linux-stable-cf9610f9116d55c5a66ef9f1faecacabd93a9322.tar.gz linux-stable-cf9610f9116d55c5a66ef9f1faecacabd93a9322.zip | |
Merge tag 'pinctrl-v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrlgrafted
Pull pin control updates from Linus Walleij:
"Core changes:
- Use the non-blocking mux_state_try_select() in the generic MUX pin
control back-end
- Free pin maps on pinctrl_generic_to_map() failure in the core
helpers
New hardware pin control:
- Qualcomm Maili TLMM SoC, PMG1110 PMIC, and Eliza LPASS LPI TLMM SoC
(this is for the low power audio, LPASS = Low Power Audio SubSystem
portions)
- Upboard support on top of the Intel pin controller
- Apple T6030 and T6031 support (just compatible strings)
- Samsung Exynos 8855 SoC
- Mediatek MT6858 SoC
- Rockchip RK3308B and RV1106 SoCs
- Airoha EN7523 and AN7563 SoCs
Improvements:
- Qualcomm TLMM GPIOs are unconditionally marked as wakeup capable
- Qualcomm improvements on top of the Qualcomm PDC (power domain
controller) irqchip improvements from tglx:s tree
- Qualcomm IPQ806x and IPQ9650 non-urgent pin grop fixups
- The NPCM8xx driver has been put into shape fixing many pin and
group definitions
- Some non-urgent Tegra 264 pin assignments are fixed up
- Some non-urgent fixups to Airoha AN7581 and AN7583 registers and
pin assignments, missing features etc"
* tag 'pinctrl-v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl: (130 commits)
dt-bindings: pinctrl: Convert TI DA850 pupd to DT schema
pinctrl: meson: sync some modify from A4
pinctrl: meson: a4: Add input enable pin configuration
pinctrl: realtek: rtd1625: remove unused group name spdif_sel
pinctrl: realtek: rtd1625: fix base_bit for VE4 GPIO 13
dt-bindings: pinctrl: microchip,pic32mzda-pinctrl: Convert to DT schema
Revert "Merge branch 'ib-rsk7204' into devel"
pinctrl: rockchip: Add RV1106 pinctrl support
dt-bindings: pinctrl: rockchip: Add RV1106 compatible
pinctrl: rockchip: Decode drive strength in the get function
pinctrl: fix PINCTRL_GENERIC_MUX not always being selectable
pinctrl: airoha: add support of an7563 SoC
dt-bindings: pinctrl: airoha: add support of an7563 pin controller
pinctrl: airoha: try to find chip scu node by phandle first
pinctrl: airoha: add support of en7523 SoC
dt-bindings: pinctrl: airoha: add support of en7523 pin controller
pinctrl: airoha: an7583: add support for olt pinmux
pinctrl: airoha: an7583: add support for pon_alt pinmux
pinctrl: airoha: an7583: add support for npu_uart pinmux
dt-bindings: pinctrl: airoha: an7583: add missed features
...
Diffstat (limited to 'lib/math/prime_numbers.c')
| -rw-r--r-- | lib/math/prime_numbers.c | 262 |
1 files changed, 262 insertions, 0 deletions
diff --git a/lib/math/prime_numbers.c b/lib/math/prime_numbers.c new file mode 100644 index 000000000..95a6f7960 --- /dev/null +++ b/lib/math/prime_numbers.c @@ -0,0 +1,262 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/prime_numbers.h> +#include <linux/slab.h> + +#include "prime_numbers_private.h" + +#if BITS_PER_LONG == 64 +static const struct primes small_primes = { + .last = 61, + .sz = 64, + .primes = { + BIT(2) | + BIT(3) | + BIT(5) | + BIT(7) | + BIT(11) | + BIT(13) | + BIT(17) | + BIT(19) | + BIT(23) | + BIT(29) | + BIT(31) | + BIT(37) | + BIT(41) | + BIT(43) | + BIT(47) | + BIT(53) | + BIT(59) | + BIT(61) + } +}; +#elif BITS_PER_LONG == 32 +static const struct primes small_primes = { + .last = 31, + .sz = 32, + .primes = { + BIT(2) | + BIT(3) | + BIT(5) | + BIT(7) | + BIT(11) | + BIT(13) | + BIT(17) | + BIT(19) | + BIT(23) | + BIT(29) | + BIT(31) + } +}; +#else +#error "unhandled BITS_PER_LONG" +#endif + +static DEFINE_MUTEX(lock); +static const struct primes __rcu *primes = RCU_INITIALIZER(&small_primes); + +#if IS_ENABLED(CONFIG_PRIME_NUMBERS_KUNIT_TEST) +/* + * Calls the callback under RCU lock. The callback must not retain + * the primes pointer. + */ +void with_primes(void *ctx, primes_fn fn) +{ + rcu_read_lock(); + fn(ctx, rcu_dereference(primes)); + rcu_read_unlock(); +} +EXPORT_SYMBOL(with_primes); + +EXPORT_SYMBOL(slow_is_prime_number); + +#else +static +#endif +bool slow_is_prime_number(unsigned long x) +{ + unsigned long y = int_sqrt(x); + + while (y > 1) { + if ((x % y) == 0) + break; + y--; + } + + return y == 1; +} + +static unsigned long slow_next_prime_number(unsigned long x) +{ + while (x < ULONG_MAX && !slow_is_prime_number(++x)) + ; + + return x; +} + +static unsigned long clear_multiples(unsigned long x, + unsigned long *p, + unsigned long start, + unsigned long end) +{ + unsigned long m; + + m = 2 * x; + if (m < start) + m = roundup(start, x); + + while (m < end) { + __clear_bit(m, p); + m += x; + } + + return x; +} + +static bool expand_to_next_prime(unsigned long x) +{ + const struct primes *p; + struct primes *new; + unsigned long sz, y; + + /* Betrand's Postulate (or Chebyshev's theorem) states that if n > 3, + * there is always at least one prime p between n and 2n - 2. + * Equivalently, if n > 1, then there is always at least one prime p + * such that n < p < 2n. + * + * http://mathworld.wolfram.com/BertrandsPostulate.html + * https://en.wikipedia.org/wiki/Bertrand's_postulate + */ + sz = 2 * x; + if (sz < x) + return false; + + sz = round_up(sz, BITS_PER_LONG); + new = kmalloc(sizeof(*new) + bitmap_size(sz), + GFP_KERNEL | __GFP_NOWARN); + if (!new) + return false; + + mutex_lock(&lock); + p = rcu_dereference_protected(primes, lockdep_is_held(&lock)); + if (x < p->last) { + kfree(new); + goto unlock; + } + + /* Where memory permits, track the primes using the + * Sieve of Eratosthenes. The sieve is to remove all multiples of known + * primes from the set, what remains in the set is therefore prime. + */ + bitmap_fill(new->primes, sz); + bitmap_copy(new->primes, p->primes, p->sz); + for (y = 2UL; y < sz; y = find_next_bit(new->primes, sz, y + 1)) + new->last = clear_multiples(y, new->primes, p->sz, sz); + new->sz = sz; + + BUG_ON(new->last <= x); + + rcu_assign_pointer(primes, new); + if (p != &small_primes) + kfree_rcu((struct primes *)p, rcu); + +unlock: + mutex_unlock(&lock); + return true; +} + +static void free_primes(void) +{ + const struct primes *p; + + mutex_lock(&lock); + p = rcu_dereference_protected(primes, lockdep_is_held(&lock)); + if (p != &small_primes) { + rcu_assign_pointer(primes, &small_primes); + kfree_rcu((struct primes *)p, rcu); + } + mutex_unlock(&lock); +} + +/** + * next_prime_number - return the next prime number + * @x: the starting point for searching to test + * + * A prime number is an integer greater than 1 that is only divisible by + * itself and 1. The set of prime numbers is computed using the Sieve of + * Eratoshenes (on finding a prime, all multiples of that prime are removed + * from the set) enabling a fast lookup of the next prime number larger than + * @x. If the sieve fails (memory limitation), the search falls back to using + * slow trial-divison, up to the value of ULONG_MAX (which is reported as the + * final prime as a sentinel). + * + * Returns: the next prime number larger than @x + */ +unsigned long next_prime_number(unsigned long x) +{ + const struct primes *p; + + rcu_read_lock(); + p = rcu_dereference(primes); + while (x >= p->last) { + rcu_read_unlock(); + + if (!expand_to_next_prime(x)) + return slow_next_prime_number(x); + + rcu_read_lock(); + p = rcu_dereference(primes); + } + x = find_next_bit(p->primes, p->last, x + 1); + rcu_read_unlock(); + + return x; +} +EXPORT_SYMBOL(next_prime_number); + +/** + * is_prime_number - test whether the given number is prime + * @x: the number to test + * + * A prime number is an integer greater than 1 that is only divisible by + * itself and 1. Internally a cache of prime numbers is kept (to speed up + * searching for sequential primes, see next_prime_number()), but if the number + * falls outside of that cache, its primality is tested using trial-divison. + * + * Returns: true if @x is prime, false for composite numbers. + */ +bool is_prime_number(unsigned long x) +{ + const struct primes *p; + bool result; + + rcu_read_lock(); + p = rcu_dereference(primes); + while (x >= p->sz) { + rcu_read_unlock(); + + if (!expand_to_next_prime(x)) + return slow_is_prime_number(x); + + rcu_read_lock(); + p = rcu_dereference(primes); + } + result = test_bit(x, p->primes); + rcu_read_unlock(); + + return result; +} +EXPORT_SYMBOL(is_prime_number); + +static void __exit primes_exit(void) +{ + free_primes(); +} + +module_exit(primes_exit); + +MODULE_AUTHOR("Intel Corporation"); +MODULE_DESCRIPTION("Prime number library"); +MODULE_LICENSE("GPL"); |
