mirror of
https://github.com/freebsd/freebsd-src
synced 2024-07-23 11:16:33 +00:00
9560ac4b63
We have the mechanism in place to support encoding system registers
explicitly, so use that rather than requiring LLVM 13+, which breaks our
current set of GitHub CI builds.
Fixes: 9eecef0521 ("Add an Armv8 rndr random number provider")
136 lines
3.3 KiB
C
136 lines
3.3 KiB
C
/*-
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* Copyright (c) 2022 The FreeBSD Foundation
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*
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* This software was developed by Andrew Turner under sponsorship from
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* the FreeBSD Foundation.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/conf.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/module.h>
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#include <sys/random.h>
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#include <machine/armreg.h>
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#include <dev/random/randomdev.h>
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static u_int random_rndr_read(void *, u_int);
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static bool has_rndr;
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static struct random_source random_armv8_rndr = {
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.rs_ident = "Armv8 rndr RNG",
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.rs_source = RANDOM_PURE_ARMV8,
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.rs_read = random_rndr_read,
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};
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static inline int
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random_rndr_read_one(u_long *buf)
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{
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u_long val;
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int loop, ret;
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loop = 10;
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do {
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__asm __volatile(
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/* Read the random number */
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"mrs %0, " __XSTRING(RNDRRS_REG) "\n"
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/* 1 on success, 0 on failure */
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"cset %w1, ne\n"
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: "=&r" (val), "=&r"(ret) :: "cc");
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} while (ret != 0 && --loop > 0);
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if (ret != 0)
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*buf = val;
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return (ret);
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}
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static u_int
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random_rndr_read(void *buf, u_int c)
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{
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u_long *b;
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u_int count;
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b = buf;
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for (count = 0; count < c; count += sizeof(*b)) {
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if (!random_rndr_read_one(b))
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break;
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b++;
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}
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return (count);
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}
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static int
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rndr_modevent(module_t mod, int type, void *unused)
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{
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uint64_t reg;
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int error = 0;
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switch (type) {
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case MOD_LOAD:
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has_rndr = false;
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if (get_kernel_reg(ID_AA64ISAR0_EL1, ®) &&
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ID_AA64ISAR0_RNDR_VAL(reg) != ID_AA64ISAR0_RNDR_NONE) {
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has_rndr = true;
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random_source_register(&random_armv8_rndr);
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printf("random: fast provider: \"%s\"\n",
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random_armv8_rndr.rs_ident);
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}
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break;
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case MOD_UNLOAD:
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if (has_rndr)
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random_source_deregister(&random_armv8_rndr);
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break;
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case MOD_SHUTDOWN:
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break;
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default:
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error = EOPNOTSUPP;
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break;
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}
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return (error);
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}
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static moduledata_t rndr_mod = {
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"rndr",
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rndr_modevent,
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0
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};
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DECLARE_MODULE(rndr, rndr_mod, SI_SUB_RANDOM, SI_ORDER_FOURTH);
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MODULE_VERSION(rndr, 1);
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MODULE_DEPEND(rndr, random_harvestq, 1, 1, 1);
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