2015-07-10 17:21:29 +02:00
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# Commit 3c694aec08dda782d9c866e599b848dff86f474f
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# Date 2015-05-13 15:00:58 +0200
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# Author David Vrabel <david.vrabel@citrix.com>
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# Committer Jan Beulich <jbeulich@suse.com>
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x86: provide add_sized()
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add_sized(ptr, inc) adds inc to the value at ptr using only the correct
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size of loads and stores for the type of *ptr. The add is /not/ atomic.
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This is needed for ticket locks to ensure the increment of the head ticket
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does not affect the tail ticket.
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Signed-off-by: David Vrabel <david.vrabel@citrix.com>
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2015-08-27 00:28:15 +02:00
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--- a/xen/include/asm-x86/atomic.h
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+++ b/xen/include/asm-x86/atomic.h
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2015-07-10 17:21:29 +02:00
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@@ -14,6 +14,14 @@ static inline void name(volatile type *a
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{ asm volatile("mov" size " %1,%0": "=m" (*(volatile type *)addr) \
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:reg (val) barrier); }
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+#define build_add_sized(name, size, type, reg) \
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+ static inline void name(volatile type *addr, type val) \
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+ { \
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+ asm volatile("add" size " %1,%0" \
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+ : "=m" (*addr) \
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+ : reg (val)); \
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+ }
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+
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build_read_atomic(read_u8_atomic, "b", uint8_t, "=q", )
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build_read_atomic(read_u16_atomic, "w", uint16_t, "=r", )
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build_read_atomic(read_u32_atomic, "l", uint32_t, "=r", )
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@@ -25,8 +33,14 @@ build_write_atomic(write_u32_atomic, "l"
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build_read_atomic(read_u64_atomic, "q", uint64_t, "=r", )
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build_write_atomic(write_u64_atomic, "q", uint64_t, "r", )
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+build_add_sized(add_u8_sized, "b", uint8_t, "qi")
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+build_add_sized(add_u16_sized, "w", uint16_t, "ri")
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+build_add_sized(add_u32_sized, "l", uint32_t, "ri")
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+build_add_sized(add_u64_sized, "q", uint64_t, "ri")
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+
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#undef build_read_atomic
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#undef build_write_atomic
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+#undef build_add_sized
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void __bad_atomic_size(void);
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@@ -54,6 +68,18 @@ void __bad_atomic_size(void);
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__x; \
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})
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+#define add_sized(p, x) ({ \
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+ typeof(*(p)) x_ = (x); \
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+ switch ( sizeof(*(p)) ) \
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+ { \
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+ case 1: add_u8_sized((uint8_t *)(p), x_); break; \
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+ case 2: add_u16_sized((uint16_t *)(p), x_); break; \
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+ case 4: add_u32_sized((uint32_t *)(p), x_); break; \
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+ case 8: add_u64_sized((uint64_t *)(p), x_); break; \
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+ default: __bad_atomic_size(); break; \
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+ } \
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+})
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+
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/*
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* NB. I've pushed the volatile qualifier into the operations. This allows
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* fast accessors such as _atomic_read() and _atomic_set() which don't give
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