Viewing file:  linux-atomic.c (9.48 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
/* Linux-specific atomic operations for ARM EABI.
Copyright (C) 2008-2022 Free Software Foundation, Inc.
Contributed by CodeSourcery.
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/>. */
/* Kernel helper for compare-and-exchange. */
typedef int (__kernel_cmpxchg_t) (int oldval, int newval, int *ptr);
#define STR(X) #X
#define XSTR(X) STR(X)
#define KERNEL_CMPXCHG 0xffff0fc0
#if __FDPIC__
/* Non-FDPIC ABIs call __kernel_cmpxchg directly by dereferencing its
address, but under FDPIC we would generate a broken call
sequence. That's why we have to implement __kernel_cmpxchg and
__kernel_dmb here: this way, the FDPIC call sequence works. */
#define __kernel_cmpxchg __fdpic_cmpxchg
#else
#define __kernel_cmpxchg (*(__kernel_cmpxchg_t *) KERNEL_CMPXCHG)
#endif
/* Kernel helper for memory barrier. */
typedef void (__kernel_dmb_t) (void);
#define KERNEL_DMB 0xffff0fa0
#if __FDPIC__
#define __kernel_dmb __fdpic_dmb
#else
#define __kernel_dmb (*(__kernel_dmb_t *) KERNEL_DMB)
#endif
#if __FDPIC__
static int __fdpic_cmpxchg (int oldval, int newval, int *ptr)
{
int result;
asm volatile (
"ldr ip, 1f\n\t"
"bx ip\n\t"
"1:\n\t"
".word " XSTR(KERNEL_CMPXCHG) "\n\t"
: "=r" (result)
: "r" (oldval) , "r" (newval), "r" (ptr)
: "r3", "memory");
/* The result is actually returned by the kernel helper, we need
this to avoid a warning. */
return result;
}
static void __fdpic_dmb (void)
{
asm volatile (
"ldr ip, 1f\n\t"
"bx ip\n\t"
"1:\n\t"
".word " XSTR(KERNEL_DMB) "\n\t"
);
}
#endif
/* Note: we implement byte, short and int versions of atomic operations using
the above kernel helpers; see linux-atomic-64bit.c for "long long" (64-bit)
operations. */
#define HIDDEN __attribute__ ((visibility ("hidden")))
#ifdef __ARMEL__
#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 int) ptr & ~3); \
unsigned int mask, shift, oldval, newval; \
int failure; \
\
shift = (((unsigned int) 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, , +, short, 2, oldval)
SUBWORD_SYNC_OP (sub, , -, short, 2, oldval)
SUBWORD_SYNC_OP (or, , |, short, 2, oldval)
SUBWORD_SYNC_OP (and, , &, short, 2, oldval)
SUBWORD_SYNC_OP (xor, , ^, short, 2, oldval)
SUBWORD_SYNC_OP (nand, ~, &, short, 2, oldval)
SUBWORD_SYNC_OP (add, , +, signed char, 1, oldval)
SUBWORD_SYNC_OP (sub, , -, signed char, 1, oldval)
SUBWORD_SYNC_OP (or, , |, signed char, 1, oldval)
SUBWORD_SYNC_OP (and, , &, signed char, 1, oldval)
SUBWORD_SYNC_OP (xor, , ^, signed char, 1, oldval)
SUBWORD_SYNC_OP (nand, ~, &, signed 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, , +, short, 2, newval)
SUBWORD_SYNC_OP (sub, , -, short, 2, newval)
SUBWORD_SYNC_OP (or, , |, short, 2, newval)
SUBWORD_SYNC_OP (and, , &, short, 2, newval)
SUBWORD_SYNC_OP (xor, , ^, short, 2, newval)
SUBWORD_SYNC_OP (nand, ~, &, short, 2, newval)
SUBWORD_SYNC_OP (add, , +, signed char, 1, newval)
SUBWORD_SYNC_OP (sub, , -, signed char, 1, newval)
SUBWORD_SYNC_OP (or, , |, signed char, 1, newval)
SUBWORD_SYNC_OP (and, , &, signed char, 1, newval)
SUBWORD_SYNC_OP (xor, , ^, signed char, 1, newval)
SUBWORD_SYNC_OP (nand, ~, &, signed 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 (__builtin_expect (oldval != actual_oldval, 0))
return actual_oldval;
fail = __kernel_cmpxchg (actual_oldval, newval, ptr);
if (__builtin_expect (!fail, 1))
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 int) ptr & ~3), fail; \
unsigned int mask, shift, actual_oldval, actual_newval; \
\
shift = (((unsigned int) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH; \
mask = MASK_##WIDTH << shift; \
\
while (1) \
{ \
actual_oldval = *wordptr; \
\
if (__builtin_expect (((actual_oldval & mask) >> shift) != \
((unsigned int) oldval & MASK_##WIDTH), 0)) \
return (actual_oldval & mask) >> shift; \
\
actual_newval = (actual_oldval & ~mask) \
| (((unsigned int) newval << shift) & mask); \
\
fail = __kernel_cmpxchg (actual_oldval, actual_newval, \
wordptr); \
\
if (__builtin_expect (!fail, 1)) \
return oldval; \
} \
}
SUBWORD_VAL_CAS (short, 2)
SUBWORD_VAL_CAS (signed 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 (short, 2)
SUBWORD_BOOL_CAS (signed char, 1)
void HIDDEN
__sync_synchronize (void)
{
__kernel_dmb ();
}
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 int) ptr & ~3); \
\
shift = (((unsigned int) 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 (short, 2)
SUBWORD_TEST_AND_SET (signed 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. */ \
__kernel_dmb (); \
*ptr = 0; \
}
SYNC_LOCK_RELEASE (long long, 8)
SYNC_LOCK_RELEASE (int, 4)
SYNC_LOCK_RELEASE (short, 2)
SYNC_LOCK_RELEASE (char, 1)
|
