/* $NetBSD: atomic_init_m68k.c,v 1.2 2025/12/20 16:25:09 thorpej Exp $ */ /*- * Copyright (c) 2008, 2025 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jason R. Thorpe. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ #include __RCSID("$NetBSD: atomic_init_m68k.c,v 1.2 2025/12/20 16:25:09 thorpej Exp $"); #include "extern.h" #include "../../../atomic/atomic_op_namespace.h" #include #include #include #include /* __sysctl syscall stub */ #include "../../../../../../lib/libc/include/__sysctl.h" #include #include /* * libc glue for m68k atomic operations. * * 68020 and later have a CAS instruction that can be used to implement * everything. However, CAS (and TAS) are unusable on some 68020 systems * (see __HAVE_M68K_BROKEN_RMC). * * The 68010 has no CAS instruction. * * So, for BROKEN_RMC and 68010, we use a restartable atomic sequence. * * Whichever compare-and-swap implementation is chosen is used to implement * all of the other atomic operations: * * ==> The *_nv() variants generally require a compare-and-swap implementation * anyway. * * ==> The other single-instruction operations (ADDx, ORx, etc.) are not * truly atomic in that they do not generate a non-interruptible bus * cycle, and thus would not work in a multi-processor environment. * (We don't support any multiprocessor m68k systems today, but hey, * it could happen!) */ extern uint32_t _atomic_cas_32_ras(volatile uint32_t *, uint32_t, uint32_t); RAS_DECL(_atomic_cas_32_ras); extern uint16_t _atomic_cas_16_ras(volatile uint16_t *, uint16_t, uint16_t); RAS_DECL(_atomic_cas_16_ras); extern uint8_t _atomic_cas_8_ras(volatile uint8_t *, uint8_t, uint8_t); RAS_DECL(_atomic_cas_8_ras); #ifdef __mc68010__ #define CAS32_DEFAULT \ ((uint32_t (*)(volatile uint32_t *, uint32_t, uint32_t))abort) #define CAS16_DEFAULT \ ((uint16_t (*)(volatile uint16_t *, uint16_t, uint16_t))abort) #define CAS8_DEFAULT \ ((uint8_t (*)(volatile uint8_t *, uint8_t, uint8_t))abort) #else extern uint32_t _atomic_cas_32_casl(volatile uint32_t *, uint32_t, uint32_t); extern uint16_t _atomic_cas_16_casw(volatile uint16_t *, uint16_t, uint16_t); extern uint8_t _atomic_cas_8_casb(volatile uint8_t *, uint8_t, uint8_t); /* Default to CASx implementation, fall back on RAS only when necessary. */ #define CAS32_DEFAULT _atomic_cas_32_casl #define CAS16_DEFAULT _atomic_cas_16_casw #define CAS8_DEFAULT _atomic_cas_8_casb #endif /* ! __mc68010__ */ static uint32_t (*_atomic_cas_32_fn)(volatile uint32_t *, uint32_t, uint32_t); static uint16_t (*_atomic_cas_16_fn)(volatile uint16_t *, uint16_t, uint16_t); static uint8_t (*_atomic_cas_8_fn)(volatile uint8_t *, uint8_t, uint8_t); void *_atomic_cas_32_a0(volatile uint32_t *, uint32_t, uint32_t); void * _atomic_cas_32_a0(volatile uint32_t *ptr, uint32_t old, uint32_t new) { /* Force return value to be duplicated into %a0. */ return (void *)(*_atomic_cas_32_fn)(ptr, old, new); } #undef atomic_cas_32 #undef atomic_cas_uint #undef atomic_cas_ulong #undef atomic_cas_ptr #undef atomic_cas_32_ni #undef atomic_cas_uint_ni #undef atomic_cas_ulong_ni #undef atomic_cas_ptr_ni __strong_alias(_atomic_cas_32,_atomic_cas_32_a0) atomic_op_alias(atomic_cas_32,_atomic_cas_32_a0) atomic_op_alias(atomic_cas_uint,_atomic_cas_32_a0) __strong_alias(_atomic_cas_uint,_atomic_cas_32_a0) atomic_op_alias(atomic_cas_ulong,_atomic_cas_32_a0) __strong_alias(_atomic_cas_ulong,_atomic_cas_32_a0) atomic_op_alias(atomic_cas_ptr,_atomic_cas_32_a0) __strong_alias(_atomic_cas_ptr,_atomic_cas_32_a0) atomic_op_alias(atomic_cas_32_ni,_atomic_cas_32_a0) __strong_alias(_atomic_cas_32_ni,_atomic_cas_32_a0) atomic_op_alias(atomic_cas_uint_ni,_atomic_cas_32_a0) __strong_alias(_atomic_cas_uint_ni,_atomic_cas_32_a0) atomic_op_alias(atomic_cas_ulong_ni,_atomic_cas_32_a0) __strong_alias(_atomic_cas_ulong_ni,_atomic_cas_32_a0) atomic_op_alias(atomic_cas_ptr_ni,_atomic_cas_32_a0) __strong_alias(_atomic_cas_ptr_ni,_atomic_cas_32_a0) crt_alias(__sync_val_compare_and_swap_4,_atomic_cas_32_a0) uint16_t _atomic_cas_16(volatile uint16_t *ptr, uint16_t old, uint16_t new) { return (*_atomic_cas_16_fn)(ptr, old, new); } #undef atomic_cas_16 atomic_op_alias(atomic_cas_16,_atomic_cas_16) crt_alias(__sync_val_compare_and_swap_2,_atomic_cas_16) uint8_t _atomic_cas_8(volatile uint8_t *ptr, uint8_t old, uint8_t new) { return (*_atomic_cas_8_fn)(ptr, old, new); } #undef atomic_cas_8 atomic_op_alias(atomic_cas_8,_atomic_cas_8) crt_alias(__sync_val_compare_and_swap_1,_atomic_cas_8) void __section(".text.startup") __attribute__ ((__visibility__("hidden"))) __libc_atomic_init(void) { _atomic_cas_32_fn = CAS32_DEFAULT; _atomic_cas_16_fn = CAS16_DEFAULT; _atomic_cas_8_fn = CAS8_DEFAULT; #ifndef __mc68010__ int mib[2]; size_t len; bool broken_rmc; /* * Check to see if this system has a non-working /RMC. If * the __sysctl() call fails, or if it indicates that /RMC * works fine, then we have no further work to do because * the stubs default to the CASx-using _atomic_cas_*() * functions. */ mib[0] = CTL_MACHDEP; mib[1] = CPU_BROKEN_RMC; len = sizeof(broken_rmc); if (__sysctl(mib, 2, &broken_rmc, &len, NULL, 0) == -1 || !broken_rmc) { return; } #endif /* ! __mc68010__ */ /* * If we get here, we either have a broken RMC system or a * 68010. In either case, we need to register the restartable * atomic sequences with the kernel. * * XXX Should consider a lazy initialization of these. */ if (rasctl(RAS_ADDR(_atomic_cas_32_ras), RAS_SIZE(_atomic_cas_32_ras), RAS_INSTALL) == 0) { _atomic_cas_32_fn = _atomic_cas_32_ras; } if (rasctl(RAS_ADDR(_atomic_cas_16_ras), RAS_SIZE(_atomic_cas_16_ras), RAS_INSTALL) == 0) { _atomic_cas_16_fn = _atomic_cas_16_ras; } if (rasctl(RAS_ADDR(_atomic_cas_8_ras), RAS_SIZE(_atomic_cas_8_ras), RAS_INSTALL) == 0) { _atomic_cas_8_fn = _atomic_cas_8_ras; } }