aboutsummaryrefslogtreecommitdiffstats
path: root/tools/include/linux/prandom.h
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2025-04-01 10:06:52 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2025-04-01 10:06:52 -0700
commitd6b02199cde4b9cb99b311eeab1cdbe23165082c (patch)
tree408f91cb2a6241098bd42f04bd15b2848953ea28 /tools/include/linux/prandom.h
parentMerge tag 'mm-stable-2025-03-30-16-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm (diff)
parentmailmap: consolidate email addresses of Alexander Sverdlin (diff)
downloadlinux-rng-d6b02199cde4b9cb99b311eeab1cdbe23165082c.tar.xz
linux-rng-d6b02199cde4b9cb99b311eeab1cdbe23165082c.zip
Merge tag 'mm-nonmm-stable-2025-03-30-18-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull non-MM updates from Andrew Morton: - The series "powerpc/crash: use generic crashkernel reservation" from Sourabh Jain changes powerpc's kexec code to use more of the generic layers. - The series "get_maintainer: report subsystem status separately" from Vlastimil Babka makes some long-requested improvements to the get_maintainer output. - The series "ucount: Simplify refcounting with rcuref_t" from Sebastian Siewior cleans up and optimizing the refcounting in the ucount code. - The series "reboot: support runtime configuration of emergency hw_protection action" from Ahmad Fatoum improves the ability for a driver to perform an emergency system shutdown or reboot. - The series "Converge on using secs_to_jiffies() part two" from Easwar Hariharan performs further migrations from msecs_to_jiffies() to secs_to_jiffies(). - The series "lib/interval_tree: add some test cases and cleanup" from Wei Yang permits more userspace testing of kernel library code, adds some more tests and performs some cleanups. - The series "hung_task: Dump the blocking task stacktrace" from Masami Hiramatsu arranges for the hung_task detector to dump the stack of the blocking task and not just that of the blocked task. - The series "resource: Split and use DEFINE_RES*() macros" from Andy Shevchenko provides some cleanups to the resource definition macros. - Plus the usual shower of singleton patches - please see the individual changelogs for details. * tag 'mm-nonmm-stable-2025-03-30-18-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (77 commits) mailmap: consolidate email addresses of Alexander Sverdlin fs/procfs: fix the comment above proc_pid_wchan() relay: use kasprintf() instead of fixed buffer formatting resource: replace open coded variant of DEFINE_RES() resource: replace open coded variants of DEFINE_RES_*_NAMED() resource: replace open coded variant of DEFINE_RES_NAMED_DESC() resource: split DEFINE_RES_NAMED_DESC() out of DEFINE_RES_NAMED() samples: add hung_task detector mutex blocking sample hung_task: show the blocker task if the task is hung on mutex kexec_core: accept unaccepted kexec segments' destination addresses watchdog/perf: optimize bytes copied and remove manual NUL-termination lib/interval_tree: fix the comment of interval_tree_span_iter_next_gap() lib/interval_tree: skip the check before go to the right subtree lib/interval_tree: add test case for span iteration lib/interval_tree: add test case for interval_tree_iter_xxx() helpers lib/rbtree: add random seed lib/rbtree: split tests lib/rbtree: enable userland test suite for rbtree related data structure checkpatch: describe --min-conf-desc-length scripts/gdb/symbols: determine KASLR offset on s390 ...
Diffstat (limited to 'tools/include/linux/prandom.h')
-rw-r--r--tools/include/linux/prandom.h51
1 files changed, 51 insertions, 0 deletions
diff --git a/tools/include/linux/prandom.h b/tools/include/linux/prandom.h
new file mode 100644
index 000000000000..b745041ccd6a
--- /dev/null
+++ b/tools/include/linux/prandom.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __TOOLS_LINUX_PRANDOM_H
+#define __TOOLS_LINUX_PRANDOM_H
+
+#include <linux/types.h>
+
+struct rnd_state {
+ __u32 s1, s2, s3, s4;
+};
+
+/*
+ * Handle minimum values for seeds
+ */
+static inline u32 __seed(u32 x, u32 m)
+{
+ return (x < m) ? x + m : x;
+}
+
+/**
+ * prandom_seed_state - set seed for prandom_u32_state().
+ * @state: pointer to state structure to receive the seed.
+ * @seed: arbitrary 64-bit value to use as a seed.
+ */
+static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
+{
+ u32 i = ((seed >> 32) ^ (seed << 10) ^ seed) & 0xffffffffUL;
+
+ state->s1 = __seed(i, 2U);
+ state->s2 = __seed(i, 8U);
+ state->s3 = __seed(i, 16U);
+ state->s4 = __seed(i, 128U);
+}
+
+/**
+ * prandom_u32_state - seeded pseudo-random number generator.
+ * @state: pointer to state structure holding seeded state.
+ *
+ * This is used for pseudo-randomness with no outside seeding.
+ * For more random results, use get_random_u32().
+ */
+static inline u32 prandom_u32_state(struct rnd_state *state)
+{
+#define TAUSWORTHE(s, a, b, c, d) (((s & c) << d) ^ (((s << a) ^ s) >> b))
+ state->s1 = TAUSWORTHE(state->s1, 6U, 13U, 4294967294U, 18U);
+ state->s2 = TAUSWORTHE(state->s2, 2U, 27U, 4294967288U, 2U);
+ state->s3 = TAUSWORTHE(state->s3, 13U, 21U, 4294967280U, 7U);
+ state->s4 = TAUSWORTHE(state->s4, 3U, 12U, 4294967168U, 13U);
+
+ return (state->s1 ^ state->s2 ^ state->s3 ^ state->s4);
+}
+#endif // __TOOLS_LINUX_PRANDOM_H