331 lines
9.5 KiB
C
331 lines
9.5 KiB
C
/* Linux-specific atomic operations for ARM EABI.
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Copyright (C) 2008-2020 Free Software Foundation, Inc.
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Contributed by CodeSourcery.
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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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/* Kernel helper for compare-and-exchange. */
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typedef int (__kernel_cmpxchg_t) (int oldval, int newval, int *ptr);
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#define STR(X) #X
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#define XSTR(X) STR(X)
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#define KERNEL_CMPXCHG 0xffff0fc0
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#if __FDPIC__
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/* Non-FDPIC ABIs call __kernel_cmpxchg directly by dereferencing its
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address, but under FDPIC we would generate a broken call
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sequence. That's why we have to implement __kernel_cmpxchg and
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__kernel_dmb here: this way, the FDPIC call sequence works. */
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#define __kernel_cmpxchg __fdpic_cmpxchg
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#else
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#define __kernel_cmpxchg (*(__kernel_cmpxchg_t *) KERNEL_CMPXCHG)
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#endif
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/* Kernel helper for memory barrier. */
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typedef void (__kernel_dmb_t) (void);
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#define KERNEL_DMB 0xffff0fa0
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#if __FDPIC__
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#define __kernel_dmb __fdpic_dmb
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#else
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#define __kernel_dmb (*(__kernel_dmb_t *) KERNEL_DMB)
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#endif
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#if __FDPIC__
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static int __fdpic_cmpxchg (int oldval, int newval, int *ptr)
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{
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int result;
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asm volatile (
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"ldr ip, 1f\n\t"
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"bx ip\n\t"
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"1:\n\t"
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".word " XSTR(KERNEL_CMPXCHG) "\n\t"
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: "=r" (result)
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: "r" (oldval) , "r" (newval), "r" (ptr)
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: "r3", "memory");
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/* The result is actually returned by the kernel helper, we need
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this to avoid a warning. */
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return result;
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}
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static void __fdpic_dmb (void)
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{
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asm volatile (
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"ldr ip, 1f\n\t"
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"bx ip\n\t"
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"1:\n\t"
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".word " XSTR(KERNEL_DMB) "\n\t"
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);
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}
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#endif
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/* Note: we implement byte, short and int versions of atomic operations using
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the above kernel helpers; see linux-atomic-64bit.c for "long long" (64-bit)
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operations. */
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#define HIDDEN __attribute__ ((visibility ("hidden")))
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#ifdef __ARMEL__
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#define INVERT_MASK_1 0
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#define INVERT_MASK_2 0
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#else
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#define INVERT_MASK_1 24
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#define INVERT_MASK_2 16
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#endif
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#define MASK_1 0xffu
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#define MASK_2 0xffffu
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#define FETCH_AND_OP_WORD(OP, PFX_OP, INF_OP) \
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int HIDDEN \
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__sync_fetch_and_##OP##_4 (int *ptr, int val) \
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{ \
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int failure, tmp; \
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\
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do { \
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tmp = *ptr; \
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failure = __kernel_cmpxchg (tmp, PFX_OP (tmp INF_OP val), 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_WORD (add, , +)
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FETCH_AND_OP_WORD (sub, , -)
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FETCH_AND_OP_WORD (or, , |)
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FETCH_AND_OP_WORD (and, , &)
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FETCH_AND_OP_WORD (xor, , ^)
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FETCH_AND_OP_WORD (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 SUBWORD_SYNC_OP(OP, PFX_OP, INF_OP, TYPE, WIDTH, RETURN) \
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TYPE HIDDEN \
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NAME##_##RETURN (OP, WIDTH) (TYPE *ptr, TYPE val) \
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{ \
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int *wordptr = (int *) ((unsigned int) ptr & ~3); \
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unsigned int mask, shift, oldval, newval; \
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int failure; \
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\
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shift = (((unsigned int) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH; \
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mask = MASK_##WIDTH << shift; \
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\
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do { \
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oldval = *wordptr; \
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newval = ((PFX_OP (((oldval & mask) >> shift) \
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INF_OP (unsigned int) val)) << shift) & mask; \
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newval |= oldval & ~mask; \
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failure = __kernel_cmpxchg (oldval, newval, wordptr); \
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} while (failure != 0); \
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\
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return (RETURN & mask) >> shift; \
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}
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SUBWORD_SYNC_OP (add, , +, short, 2, oldval)
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SUBWORD_SYNC_OP (sub, , -, short, 2, oldval)
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SUBWORD_SYNC_OP (or, , |, short, 2, oldval)
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SUBWORD_SYNC_OP (and, , &, short, 2, oldval)
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SUBWORD_SYNC_OP (xor, , ^, short, 2, oldval)
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SUBWORD_SYNC_OP (nand, ~, &, short, 2, oldval)
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SUBWORD_SYNC_OP (add, , +, signed char, 1, oldval)
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SUBWORD_SYNC_OP (sub, , -, signed char, 1, oldval)
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SUBWORD_SYNC_OP (or, , |, signed char, 1, oldval)
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SUBWORD_SYNC_OP (and, , &, signed char, 1, oldval)
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SUBWORD_SYNC_OP (xor, , ^, signed char, 1, oldval)
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SUBWORD_SYNC_OP (nand, ~, &, signed char, 1, oldval)
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#define OP_AND_FETCH_WORD(OP, PFX_OP, INF_OP) \
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int HIDDEN \
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__sync_##OP##_and_fetch_4 (int *ptr, int val) \
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{ \
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int tmp, failure; \
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\
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do { \
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tmp = *ptr; \
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failure = __kernel_cmpxchg (tmp, PFX_OP (tmp INF_OP val), ptr); \
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} while (failure != 0); \
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\
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return PFX_OP (tmp INF_OP val); \
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}
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OP_AND_FETCH_WORD (add, , +)
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OP_AND_FETCH_WORD (sub, , -)
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OP_AND_FETCH_WORD (or, , |)
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OP_AND_FETCH_WORD (and, , &)
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OP_AND_FETCH_WORD (xor, , ^)
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OP_AND_FETCH_WORD (nand, ~, &)
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SUBWORD_SYNC_OP (add, , +, short, 2, newval)
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SUBWORD_SYNC_OP (sub, , -, short, 2, newval)
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SUBWORD_SYNC_OP (or, , |, short, 2, newval)
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SUBWORD_SYNC_OP (and, , &, short, 2, newval)
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SUBWORD_SYNC_OP (xor, , ^, short, 2, newval)
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SUBWORD_SYNC_OP (nand, ~, &, short, 2, newval)
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SUBWORD_SYNC_OP (add, , +, signed char, 1, newval)
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SUBWORD_SYNC_OP (sub, , -, signed char, 1, newval)
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SUBWORD_SYNC_OP (or, , |, signed char, 1, newval)
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SUBWORD_SYNC_OP (and, , &, signed char, 1, newval)
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SUBWORD_SYNC_OP (xor, , ^, signed char, 1, newval)
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SUBWORD_SYNC_OP (nand, ~, &, signed char, 1, newval)
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int HIDDEN
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__sync_val_compare_and_swap_4 (int *ptr, int oldval, int newval)
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{
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int actual_oldval, fail;
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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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fail = __kernel_cmpxchg (actual_oldval, newval, ptr);
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if (__builtin_expect (!fail, 1))
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return oldval;
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}
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}
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#define SUBWORD_VAL_CAS(TYPE, WIDTH) \
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TYPE HIDDEN \
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__sync_val_compare_and_swap_##WIDTH (TYPE *ptr, TYPE oldval, \
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TYPE newval) \
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{ \
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int *wordptr = (int *)((unsigned int) ptr & ~3), fail; \
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unsigned int mask, shift, actual_oldval, actual_newval; \
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\
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shift = (((unsigned int) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH; \
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mask = MASK_##WIDTH << shift; \
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\
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while (1) \
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{ \
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actual_oldval = *wordptr; \
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\
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if (__builtin_expect (((actual_oldval & mask) >> shift) != \
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((unsigned int) oldval & MASK_##WIDTH), 0)) \
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return (actual_oldval & mask) >> shift; \
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\
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actual_newval = (actual_oldval & ~mask) \
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| (((unsigned int) newval << shift) & mask); \
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\
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fail = __kernel_cmpxchg (actual_oldval, actual_newval, \
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wordptr); \
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\
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if (__builtin_expect (!fail, 1)) \
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return oldval; \
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} \
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}
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SUBWORD_VAL_CAS (short, 2)
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SUBWORD_VAL_CAS (signed char, 1)
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typedef unsigned char bool;
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bool HIDDEN
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__sync_bool_compare_and_swap_4 (int *ptr, int oldval, int newval)
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{
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int failure = __kernel_cmpxchg (oldval, newval, ptr);
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return (failure == 0);
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}
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#define SUBWORD_BOOL_CAS(TYPE, WIDTH) \
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bool HIDDEN \
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__sync_bool_compare_and_swap_##WIDTH (TYPE *ptr, TYPE oldval, \
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TYPE newval) \
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{ \
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TYPE actual_oldval \
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= __sync_val_compare_and_swap_##WIDTH (ptr, oldval, newval); \
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return (oldval == actual_oldval); \
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}
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SUBWORD_BOOL_CAS (short, 2)
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SUBWORD_BOOL_CAS (signed char, 1)
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void HIDDEN
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__sync_synchronize (void)
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{
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__kernel_dmb ();
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}
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int HIDDEN
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__sync_lock_test_and_set_4 (int *ptr, int val)
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{
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int failure, oldval;
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do {
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oldval = *ptr;
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failure = __kernel_cmpxchg (oldval, val, ptr);
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} while (failure != 0);
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return oldval;
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}
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#define SUBWORD_TEST_AND_SET(TYPE, WIDTH) \
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TYPE HIDDEN \
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__sync_lock_test_and_set_##WIDTH (TYPE *ptr, TYPE val) \
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{ \
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int failure; \
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unsigned int oldval, newval, shift, mask; \
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int *wordptr = (int *) ((unsigned int) ptr & ~3); \
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\
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shift = (((unsigned int) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH; \
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mask = MASK_##WIDTH << shift; \
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\
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do { \
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oldval = *wordptr; \
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newval = (oldval & ~mask) \
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| (((unsigned int) val << shift) & mask); \
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failure = __kernel_cmpxchg (oldval, newval, wordptr); \
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} while (failure != 0); \
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\
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return (oldval & mask) >> shift; \
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}
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SUBWORD_TEST_AND_SET (short, 2)
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SUBWORD_TEST_AND_SET (signed char, 1)
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#define SYNC_LOCK_RELEASE(TYPE, WIDTH) \
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void HIDDEN \
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__sync_lock_release_##WIDTH (TYPE *ptr) \
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{ \
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/* All writes before this point must be seen before we release \
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the lock itself. */ \
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__kernel_dmb (); \
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*ptr = 0; \
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}
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SYNC_LOCK_RELEASE (long long, 8)
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SYNC_LOCK_RELEASE (int, 4)
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SYNC_LOCK_RELEASE (short, 2)
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SYNC_LOCK_RELEASE (char, 1)
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