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734 |
jeremybenn |
/* 64bit Linux-specific atomic operations for ARM EABI.
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Copyright (C) 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
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Based on linux-atomic.c
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64 bit additions david.gilbert@linaro.org
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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/* 64bit helper functions for atomic operations; the compiler will
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call these when the code is compiled for a CPU without ldrexd/strexd.
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(If the CPU had those then the compiler inlines the operation).
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These helpers require a kernel helper that's only present on newer
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kernels; we check for that in an init section and bail out rather
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unceremoneously. */
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extern unsigned int __write (int fd, const void *buf, unsigned int count);
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extern void abort (void);
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/* Kernel helper for compare-and-exchange. */
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typedef int (__kernel_cmpxchg64_t) (const long long* oldval,
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const long long* newval,
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long long *ptr);
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#define __kernel_cmpxchg64 (*(__kernel_cmpxchg64_t *) 0xffff0f60)
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/* Kernel helper page version number. */
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#define __kernel_helper_version (*(unsigned int *)0xffff0ffc)
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/* Check that the kernel has a new enough version at load. */
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static void __check_for_sync8_kernelhelper (void)
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{
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if (__kernel_helper_version < 5)
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{
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const char err[] = "A newer kernel is required to run this binary. "
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"(__kernel_cmpxchg64 helper)\n";
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/* At this point we need a way to crash with some information
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for the user - I'm not sure I can rely on much else being
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available at this point, so do the same as generic-morestack.c
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write () and abort (). */
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__write (2 /* stderr. */, err, sizeof (err));
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abort ();
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}
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};
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static void (*__sync8_kernelhelper_inithook[]) (void)
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__attribute__ ((used, section (".init_array"))) = {
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&__check_for_sync8_kernelhelper
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};
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#define HIDDEN __attribute__ ((visibility ("hidden")))
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#define FETCH_AND_OP_WORD64(OP, PFX_OP, INF_OP) \
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long long HIDDEN \
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__sync_fetch_and_##OP##_8 (long long *ptr, long long val) \
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{ \
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int failure; \
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long long tmp,tmp2; \
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\
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do { \
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tmp = *ptr; \
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tmp2 = PFX_OP (tmp INF_OP val); \
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failure = __kernel_cmpxchg64 (&tmp, &tmp2, ptr); \
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} while (failure != 0); \
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\
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return tmp; \
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}
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FETCH_AND_OP_WORD64 (add, , +)
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FETCH_AND_OP_WORD64 (sub, , -)
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FETCH_AND_OP_WORD64 (or, , |)
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FETCH_AND_OP_WORD64 (and, , &)
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FETCH_AND_OP_WORD64 (xor, , ^)
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FETCH_AND_OP_WORD64 (nand, ~, &)
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#define NAME_oldval(OP, WIDTH) __sync_fetch_and_##OP##_##WIDTH
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#define NAME_newval(OP, WIDTH) __sync_##OP##_and_fetch_##WIDTH
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/* Implement both __sync_<op>_and_fetch and __sync_fetch_and_<op> for
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subword-sized quantities. */
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#define OP_AND_FETCH_WORD64(OP, PFX_OP, INF_OP) \
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long long HIDDEN \
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__sync_##OP##_and_fetch_8 (long long *ptr, long long val) \
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{ \
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int failure; \
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long long tmp,tmp2; \
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\
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do { \
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tmp = *ptr; \
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tmp2 = PFX_OP (tmp INF_OP val); \
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failure = __kernel_cmpxchg64 (&tmp, &tmp2, ptr); \
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} while (failure != 0); \
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\
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return tmp2; \
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}
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OP_AND_FETCH_WORD64 (add, , +)
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OP_AND_FETCH_WORD64 (sub, , -)
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OP_AND_FETCH_WORD64 (or, , |)
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OP_AND_FETCH_WORD64 (and, , &)
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OP_AND_FETCH_WORD64 (xor, , ^)
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OP_AND_FETCH_WORD64 (nand, ~, &)
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long long HIDDEN
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__sync_val_compare_and_swap_8 (long long *ptr, long long oldval,
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long long newval)
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{
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int failure;
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long long actual_oldval;
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while (1)
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{
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actual_oldval = *ptr;
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if (__builtin_expect (oldval != actual_oldval, 0))
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return actual_oldval;
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failure = __kernel_cmpxchg64 (&actual_oldval, &newval, ptr);
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if (__builtin_expect (!failure, 1))
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return oldval;
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}
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}
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typedef unsigned char bool;
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bool HIDDEN
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__sync_bool_compare_and_swap_8 (long long *ptr, long long oldval,
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long long newval)
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{
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int failure = __kernel_cmpxchg64 (&oldval, &newval, ptr);
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return (failure == 0);
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}
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long long HIDDEN
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__sync_lock_test_and_set_8 (long long *ptr, long long val)
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{
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int failure;
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long long oldval;
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do {
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oldval = *ptr;
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failure = __kernel_cmpxchg64 (&oldval, &val, ptr);
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} while (failure != 0);
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return oldval;
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}
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