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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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