| 1 |
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| 2 | |
| 3 | * Generic UP xchg and cmpxchg using interrupt disablement. Does not
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| 4 | * support SMP.
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| 5 |
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| 6 |
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| 7 | #ifndef __ASM_GENERIC_CMPXCHG_H
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| 8 | #define __ASM_GENERIC_CMPXCHG_H
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| 9 |
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| 10 | #ifdef CONFIG_SMP
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| 11 | #error "Cannot use generic cmpxchg on SMP"
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| 12 | #endif
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| 13 |
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| 14 | #include <linux/types.h>
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| 15 | #include <linux/irqflags.h>
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| 16 |
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| 17 | |
| 18 | * This function doesn't exist, so you'll get a linker error if
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| 19 | * something tries to do an invalidly-sized xchg().
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| 20 |
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| 21 | extern void __generic_xchg_called_with_bad_pointer(void);
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| 22 |
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| 23 | static inline
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| 24 | unsigned long __generic_xchg(unsigned long x, volatile void *ptr, int size)
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| 25 | {
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| 26 | unsigned long ret, flags;
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| 27 |
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| 28 | switch (size) {
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| 29 | case 1:
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| 30 | #ifdef __xchg_u8
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| 31 | return __xchg_u8(x, ptr);
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| 32 | #else
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| 33 | local_irq_save(flags);
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| 34 | ret = *(volatile u8 *)ptr;
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| 35 | *(volatile u8 *)ptr = (x & 0xffu);
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| 36 | local_irq_restore(flags);
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| 37 | return ret;
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| 38 | #endif
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| 39 |
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| 40 | case 2:
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| 41 | #ifdef __xchg_u16
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| 42 | return __xchg_u16(x, ptr);
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| 43 | #else
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| 44 | local_irq_save(flags);
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| 45 | ret = *(volatile u16 *)ptr;
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| 46 | *(volatile u16 *)ptr = (x & 0xffffu);
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| 47 | local_irq_restore(flags);
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| 48 | return ret;
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| 49 | #endif
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| 50 |
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| 51 | case 4:
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| 52 | #ifdef __xchg_u32
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| 53 | return __xchg_u32(x, ptr);
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| 54 | #else
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| 55 | local_irq_save(flags);
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| 56 | ret = *(volatile u32 *)ptr;
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| 57 | *(volatile u32 *)ptr = (x & 0xffffffffu);
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| 58 | local_irq_restore(flags);
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| 59 | return ret;
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| 60 | #endif
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| 61 |
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| 62 | #ifdef CONFIG_64BIT
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| 63 | case 8:
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| 64 | #ifdef __xchg_u64
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| 65 | return __xchg_u64(x, ptr);
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| 66 | #else
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| 67 | local_irq_save(flags);
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| 68 | ret = *(volatile u64 *)ptr;
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| 69 | *(volatile u64 *)ptr = x;
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| 70 | local_irq_restore(flags);
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| 71 | return ret;
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| 72 | #endif
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| 73 | #endif
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| 74 |
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| 75 | default:
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| 76 | __generic_xchg_called_with_bad_pointer();
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| 77 | return x;
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| 78 | }
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| 79 | }
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| 80 |
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| 81 | #define generic_xchg(ptr, x) ({ \
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| 82 | ((__typeof__(*(ptr))) \
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| 83 | __generic_xchg((unsigned long)(x), (ptr), sizeof(*(ptr)))); \
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| 84 | })
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| 85 |
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| 86 | |
| 87 | * Atomic compare and exchange.
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| 88 |
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| 89 | #include <asm-generic/cmpxchg-local.h>
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| 90 |
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| 91 | #define generic_cmpxchg_local(ptr, o, n) ({ \
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| 92 | ((__typeof__(*(ptr)))__generic_cmpxchg_local((ptr), (unsigned long)(o), \
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| 93 | (unsigned long)(n), sizeof(*(ptr)))); \
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| 94 | })
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| 95 |
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| 96 | #define generic_cmpxchg64_local(ptr, o, n) \
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| 97 | __generic_cmpxchg64_local((ptr), (o), (n))
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| 98 |
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| 99 |
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| 100 | #ifndef arch_xchg
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| 101 | #define arch_xchg generic_xchg
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| 102 | #endif
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| 103 |
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| 104 | #ifndef arch_cmpxchg_local
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| 105 | #define arch_cmpxchg_local generic_cmpxchg_local
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| 106 | #endif
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| 107 |
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| 108 | #ifndef arch_cmpxchg64_local
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| 109 | #define arch_cmpxchg64_local generic_cmpxchg64_local
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| 110 | #endif
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| 111 |
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| 112 | #define arch_cmpxchg arch_cmpxchg_local
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| 113 | #define arch_cmpxchg64 arch_cmpxchg64_local
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| 114 |
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| 115 | #endif
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