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- /* 64bit Linux-specific atomic operations for ARM EABI.
- Copyright (C) 2008-2022 Free Software Foundation, Inc.
- Based on linux-atomic.c
- 64 bit additions david.gilbert@linaro.org
- This file is part of GCC.
- GCC is free software; you can redistribute it and/or modify it under
- the terms of the GNU General Public License as published by the Free
- Software Foundation; either version 3, or (at your option) any later
- version.
- GCC is distributed in the hope that it will be useful, but WITHOUT ANY
- WARRANTY; without even the implied warranty of MERCHANTABILITY or
- FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
- for more details.
- Under Section 7 of GPL version 3, you are granted additional
- permissions described in the GCC Runtime Library Exception, version
- 3.1, as published by the Free Software Foundation.
- You should have received a copy of the GNU General Public License and
- a copy of the GCC Runtime Library Exception along with this program;
- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
- <http://www.gnu.org/licenses/>. */
- /* 64bit helper functions for atomic operations; the compiler will
- call these when the code is compiled for a CPU without ldrexd/strexd.
- (If the CPU had those then the compiler inlines the operation).
- These helpers require a kernel helper that's only present on newer
- kernels; we check for that in an init section and bail out rather
- unceremoneously. */
- extern int write (int fd, const void *buf, unsigned int count);
- extern void abort (void);
- /* Kernel helper for compare-and-exchange. */
- typedef int (__kernel_cmpxchg64_t) (const long long* oldval,
- const long long* newval,
- long long *ptr);
- #define __kernel_cmpxchg64 (*(__kernel_cmpxchg64_t *) 0xffff0f60)
- /* Kernel helper page version number. */
- #define __kernel_helper_version (*(unsigned int *)0xffff0ffc)
- /* Check that the kernel has a new enough version at load. */
- static void __check_for_sync8_kernelhelper (void)
- {
- if (__kernel_helper_version < 5)
- {
- const char err[] = "A newer kernel is required to run this binary. "
- "(__kernel_cmpxchg64 helper)\n";
- /* At this point we need a way to crash with some information
- for the user - I'm not sure I can rely on much else being
- available at this point, so do the same as generic-morestack.c
- write () and abort (). */
- write (2 /* stderr. */, err, sizeof (err));
- abort ();
- }
- };
- static void (*__sync8_kernelhelper_inithook[]) (void)
- __attribute__ ((used, section (".init_array"))) = {
- &__check_for_sync8_kernelhelper
- };
- #define HIDDEN __attribute__ ((visibility ("hidden")))
- #define FETCH_AND_OP_WORD64(OP, PFX_OP, INF_OP) \
- long long HIDDEN \
- __sync_fetch_and_##OP##_8 (long long *ptr, long long val) \
- { \
- int failure; \
- long long tmp,tmp2; \
- \
- do { \
- tmp = *ptr; \
- tmp2 = PFX_OP (tmp INF_OP val); \
- failure = __kernel_cmpxchg64 (&tmp, &tmp2, ptr); \
- } while (failure != 0); \
- \
- return tmp; \
- }
- FETCH_AND_OP_WORD64 (add, , +)
- FETCH_AND_OP_WORD64 (sub, , -)
- FETCH_AND_OP_WORD64 (or, , |)
- FETCH_AND_OP_WORD64 (and, , &)
- FETCH_AND_OP_WORD64 (xor, , ^)
- FETCH_AND_OP_WORD64 (nand, ~, &)
- #define NAME_oldval(OP, WIDTH) __sync_fetch_and_##OP##_##WIDTH
- #define NAME_newval(OP, WIDTH) __sync_##OP##_and_fetch_##WIDTH
- /* Implement both __sync_<op>_and_fetch and __sync_fetch_and_<op> for
- subword-sized quantities. */
- #define OP_AND_FETCH_WORD64(OP, PFX_OP, INF_OP) \
- long long HIDDEN \
- __sync_##OP##_and_fetch_8 (long long *ptr, long long val) \
- { \
- int failure; \
- long long tmp,tmp2; \
- \
- do { \
- tmp = *ptr; \
- tmp2 = PFX_OP (tmp INF_OP val); \
- failure = __kernel_cmpxchg64 (&tmp, &tmp2, ptr); \
- } while (failure != 0); \
- \
- return tmp2; \
- }
- OP_AND_FETCH_WORD64 (add, , +)
- OP_AND_FETCH_WORD64 (sub, , -)
- OP_AND_FETCH_WORD64 (or, , |)
- OP_AND_FETCH_WORD64 (and, , &)
- OP_AND_FETCH_WORD64 (xor, , ^)
- OP_AND_FETCH_WORD64 (nand, ~, &)
- long long HIDDEN
- __sync_val_compare_and_swap_8 (long long *ptr, long long oldval,
- long long newval)
- {
- int failure;
- long long actual_oldval;
- while (1)
- {
- actual_oldval = *ptr;
- if (__builtin_expect (oldval != actual_oldval, 0))
- return actual_oldval;
- failure = __kernel_cmpxchg64 (&actual_oldval, &newval, ptr);
- if (__builtin_expect (!failure, 1))
- return oldval;
- }
- }
- typedef unsigned char bool;
- bool HIDDEN
- __sync_bool_compare_and_swap_8 (long long *ptr, long long oldval,
- long long newval)
- {
- int failure = __kernel_cmpxchg64 (&oldval, &newval, ptr);
- return (failure == 0);
- }
- long long HIDDEN
- __sync_lock_test_and_set_8 (long long *ptr, long long val)
- {
- int failure;
- long long oldval;
- do {
- oldval = *ptr;
- failure = __kernel_cmpxchg64 (&oldval, &val, ptr);
- } while (failure != 0);
- return oldval;
- }
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