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/* Linux-specific atomic operations for Nios II Linux.
Copyright (C) 2008-2015 Free Software Foundation, Inc.
This file 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.
This file 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/>. */
/* We implement byte, short and int versions of each atomic operation
using the kernel helper defined below. There is no support for
64-bit operations yet. */
/* Crash a userspace program with SIGSEV. */
#define ABORT_INSTRUCTION asm ("stw zero, 0(zero)")
/* Kernel helper for compare-and-exchange a 32-bit value. */
static inline long
__kernel_cmpxchg (int oldval, int newval, int *mem)
{
register int r2 asm ("r2");
register int *r4 asm ("r4") = mem;
register int r5 asm ("r5") = oldval;
register int r6 asm ("r6") = newval;
/* Call the kernel provided fixed address cmpxchg helper routine. */
asm volatile ("movi %0, %4\n\t"
"callr %0\n"
: "=r" (r2)
: "r" (r4), "r" (r5), "r" (r6), "I" (0x00001004)
: "ra", "memory");
return r2;
}
#define HIDDEN __attribute__ ((visibility ("hidden")))
#ifdef __nios2_little_endian__
#define INVERT_MASK_1 0
#define INVERT_MASK_2 0
#else
#define INVERT_MASK_1 24
#define INVERT_MASK_2 16
#endif
#define MASK_1 0xffu
#define MASK_2 0xffffu
#define FETCH_AND_OP_WORD(OP, PFX_OP, INF_OP) \
int HIDDEN \
__sync_fetch_and_##OP##_4 (int *ptr, int val) \
{ \
int failure, tmp; \
\
do { \
tmp = *ptr; \
failure = __kernel_cmpxchg (tmp, PFX_OP (tmp INF_OP val), ptr); \
} while (failure != 0); \
\
return tmp; \
}
FETCH_AND_OP_WORD (add, , +)
FETCH_AND_OP_WORD (sub, , -)
FETCH_AND_OP_WORD (or, , |)
FETCH_AND_OP_WORD (and, , &)
FETCH_AND_OP_WORD (xor, , ^)
FETCH_AND_OP_WORD (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 SUBWORD_SYNC_OP(OP, PFX_OP, INF_OP, TYPE, WIDTH, RETURN) \
TYPE HIDDEN \
NAME##_##RETURN (OP, WIDTH) (TYPE *ptr, TYPE val) \
{ \
int *wordptr = (int *) ((unsigned long) ptr & ~3); \
unsigned int mask, shift, oldval, newval; \
int failure; \
\
shift = (((unsigned long) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH; \
mask = MASK_##WIDTH << shift; \
\
do { \
oldval = *wordptr; \
newval = ((PFX_OP (((oldval & mask) >> shift) \
INF_OP (unsigned int) val)) << shift) & mask; \
newval |= oldval & ~mask; \
failure = __kernel_cmpxchg (oldval, newval, wordptr); \
} while (failure != 0); \
\
return (RETURN & mask) >> shift; \
}
SUBWORD_SYNC_OP (add, , +, unsigned short, 2, oldval)
SUBWORD_SYNC_OP (sub, , -, unsigned short, 2, oldval)
SUBWORD_SYNC_OP (or, , |, unsigned short, 2, oldval)
SUBWORD_SYNC_OP (and, , &, unsigned short, 2, oldval)
SUBWORD_SYNC_OP (xor, , ^, unsigned short, 2, oldval)
SUBWORD_SYNC_OP (nand, ~, &, unsigned short, 2, oldval)
SUBWORD_SYNC_OP (add, , +, unsigned char, 1, oldval)
SUBWORD_SYNC_OP (sub, , -, unsigned char, 1, oldval)
SUBWORD_SYNC_OP (or, , |, unsigned char, 1, oldval)
SUBWORD_SYNC_OP (and, , &, unsigned char, 1, oldval)
SUBWORD_SYNC_OP (xor, , ^, unsigned char, 1, oldval)
SUBWORD_SYNC_OP (nand, ~, &, unsigned char, 1, oldval)
#define OP_AND_FETCH_WORD(OP, PFX_OP, INF_OP) \
int HIDDEN \
__sync_##OP##_and_fetch_4 (int *ptr, int val) \
{ \
int tmp, failure; \
\
do { \
tmp = *ptr; \
failure = __kernel_cmpxchg (tmp, PFX_OP (tmp INF_OP val), ptr); \
} while (failure != 0); \
\
return PFX_OP (tmp INF_OP val); \
}
OP_AND_FETCH_WORD (add, , +)
OP_AND_FETCH_WORD (sub, , -)
OP_AND_FETCH_WORD (or, , |)
OP_AND_FETCH_WORD (and, , &)
OP_AND_FETCH_WORD (xor, , ^)
OP_AND_FETCH_WORD (nand, ~, &)
SUBWORD_SYNC_OP (add, , +, unsigned short, 2, newval)
SUBWORD_SYNC_OP (sub, , -, unsigned short, 2, newval)
SUBWORD_SYNC_OP (or, , |, unsigned short, 2, newval)
SUBWORD_SYNC_OP (and, , &, unsigned short, 2, newval)
SUBWORD_SYNC_OP (xor, , ^, unsigned short, 2, newval)
SUBWORD_SYNC_OP (nand, ~, &, unsigned short, 2, newval)
SUBWORD_SYNC_OP (add, , +, unsigned char, 1, newval)
SUBWORD_SYNC_OP (sub, , -, unsigned char, 1, newval)
SUBWORD_SYNC_OP (or, , |, unsigned char, 1, newval)
SUBWORD_SYNC_OP (and, , &, unsigned char, 1, newval)
SUBWORD_SYNC_OP (xor, , ^, unsigned char, 1, newval)
SUBWORD_SYNC_OP (nand, ~, &, unsigned char, 1, newval)
int HIDDEN
__sync_val_compare_and_swap_4 (int *ptr, int oldval, int newval)
{
int actual_oldval, fail;
while (1)
{
actual_oldval = *ptr;
if (oldval != actual_oldval)
return actual_oldval;
fail = __kernel_cmpxchg (actual_oldval, newval, ptr);
if (!fail)
return oldval;
}
}
#define SUBWORD_VAL_CAS(TYPE, WIDTH) \
TYPE HIDDEN \
__sync_val_compare_and_swap_##WIDTH (TYPE *ptr, TYPE oldval, \
TYPE newval) \
{ \
int *wordptr = (int *)((unsigned long) ptr & ~3), fail; \
unsigned int mask, shift, actual_oldval, actual_newval; \
\
shift = (((unsigned long) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH; \
mask = MASK_##WIDTH << shift; \
\
while (1) \
{ \
actual_oldval = *wordptr; \
\
if (((actual_oldval & mask) >> shift) != (unsigned int) oldval) \
return (actual_oldval & mask) >> shift; \
\
actual_newval = (actual_oldval & ~mask) \
| (((unsigned int) newval << shift) & mask); \
\
fail = __kernel_cmpxchg (actual_oldval, actual_newval, \
wordptr); \
\
if (!fail) \
return oldval; \
} \
}
SUBWORD_VAL_CAS (unsigned short, 2)
SUBWORD_VAL_CAS (unsigned char, 1)
typedef unsigned char bool;
bool HIDDEN
__sync_bool_compare_and_swap_4 (int *ptr, int oldval, int newval)
{
int failure = __kernel_cmpxchg (oldval, newval, ptr);
return (failure == 0);
}
#define SUBWORD_BOOL_CAS(TYPE, WIDTH) \
bool HIDDEN \
__sync_bool_compare_and_swap_##WIDTH (TYPE *ptr, TYPE oldval, \
TYPE newval) \
{ \
TYPE actual_oldval \
= __sync_val_compare_and_swap_##WIDTH (ptr, oldval, newval); \
return (oldval == actual_oldval); \
}
SUBWORD_BOOL_CAS (unsigned short, 2)
SUBWORD_BOOL_CAS (unsigned char, 1)
int HIDDEN
__sync_lock_test_and_set_4 (int *ptr, int val)
{
int failure, oldval;
do {
oldval = *ptr;
failure = __kernel_cmpxchg (oldval, val, ptr);
} while (failure != 0);
return oldval;
}
#define SUBWORD_TEST_AND_SET(TYPE, WIDTH) \
TYPE HIDDEN \
__sync_lock_test_and_set_##WIDTH (TYPE *ptr, TYPE val) \
{ \
int failure; \
unsigned int oldval, newval, shift, mask; \
int *wordptr = (int *) ((unsigned long) ptr & ~3); \
\
shift = (((unsigned long) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH; \
mask = MASK_##WIDTH << shift; \
\
do { \
oldval = *wordptr; \
newval = (oldval & ~mask) \
| (((unsigned int) val << shift) & mask); \
failure = __kernel_cmpxchg (oldval, newval, wordptr); \
} while (failure != 0); \
\
return (oldval & mask) >> shift; \
}
SUBWORD_TEST_AND_SET (unsigned short, 2)
SUBWORD_TEST_AND_SET (unsigned char, 1)
#define SYNC_LOCK_RELEASE(TYPE, WIDTH) \
void HIDDEN \
__sync_lock_release_##WIDTH (TYPE *ptr) \
{ \
/* All writes before this point must be seen before we release \
the lock itself. */ \
__builtin_sync (); \
*ptr = 0; \
}
SYNC_LOCK_RELEASE (int, 4)
SYNC_LOCK_RELEASE (short, 2)
SYNC_LOCK_RELEASE (char, 1)
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