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cmpxchg.h
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#ifndef ASM_X86_CMPXCHG_H #define ASM_X86_CMPXCHG_H #include <linux/compiler.h> #include <asm/cpufeatures.h> #include <asm/alternative.h> /* Provides LOCK_PREFIX */ /* * Non-existant functions to indicate usage errors at link time * (or compile-time if the compiler implements __compiletime_error(). */ extern void __xchg_wrong_size(void) __compiletime_error("Bad argument size for xchg"); extern void __cmpxchg_wrong_size(void) __compiletime_error("Bad argument size for cmpxchg"); extern void __xadd_wrong_size(void) __compiletime_error("Bad argument size for xadd"); extern void __add_wrong_size(void) __compiletime_error("Bad argument size for add"); /* * Constants for operation sizes. On 32-bit, the 64-bit size it set to * -1 because sizeof will never return -1, thereby making those switch * case statements guaranteeed dead code which the compiler will * eliminate, and allowing the "missing symbol in the default case" to * indicate a usage error. */ #define __X86_CASE_B 1 #define __X86_CASE_W 2 #define __X86_CASE_L 4 #ifdef CONFIG_64BIT #define __X86_CASE_Q 8 #else #define __X86_CASE_Q -1 /* sizeof will never return -1 */ #endif /* * An exchange-type operation, which takes a value and a pointer, and * returns the old value. */ #define __xchg_op(ptr, arg, op, lock) \ ({ \ __typeof__ (*(ptr)) __ret = (arg); \ switch (sizeof(*(ptr))) { \ case __X86_CASE_B: \ asm volatile (lock #op "b %b0, %1\n" \ : "+q" (__ret), "+m" (*(ptr)) \ : : "memory", "cc"); \ break; \ case __X86_CASE_W: \ asm volatile (lock #op "w %w0, %1\n" \ : "+r" (__ret), "+m" (*(ptr)) \ : : "memory", "cc"); \ break; \ case __X86_CASE_L: \ asm volatile (lock #op "l %0, %1\n" \ : "+r" (__ret), "+m" (*(ptr)) \ : : "memory", "cc"); \ break; \ case __X86_CASE_Q: \ asm volatile (lock #op "q %q0, %1\n" \ : "+r" (__ret), "+m" (*(ptr)) \ : : "memory", "cc"); \ break; \ default: \ __ ## op ## _wrong_size(); \ } \ __ret; \ }) /* * Note: no "lock" prefix even on SMP: xchg always implies lock anyway. * Since this is generally used to protect other memory information, we * use "asm volatile" and "memory" clobbers to prevent gcc from moving * information around. */ #define xchg(ptr, v) __xchg_op((ptr), (v), xchg, "") /* * Atomic compare and exchange. Compare OLD with MEM, if identical, * store NEW in MEM. Return the initial value in MEM. Success is * indicated by comparing RETURN with OLD. */ #define __raw_cmpxchg(ptr, old, new, size, lock) \ ({ \ __typeof__(*(ptr)) __ret; \ __typeof__(*(ptr)) __old = (old); \ __typeof__(*(ptr)) __new = (new); \ switch (size) { \ case __X86_CASE_B: \ { \ volatile u8 *__ptr = (volatile u8 *)(ptr); \ asm volatile(lock "cmpxchgb %2,%1" \ : "=a" (__ret), "+m" (*__ptr) \ : "q" (__new), "0" (__old) \ : "memory"); \ break; \ } \ case __X86_CASE_W: \ { \ volatile u16 *__ptr = (volatile u16 *)(ptr); \ asm volatile(lock "cmpxchgw %2,%1" \ : "=a" (__ret), "+m" (*__ptr) \ : "r" (__new), "0" (__old) \ : "memory"); \ break; \ } \ case __X86_CASE_L: \ { \ volatile u32 *__ptr = (volatile u32 *)(ptr); \ asm volatile(lock "cmpxchgl %2,%1" \ : "=a" (__ret), "+m" (*__ptr) \ : "r" (__new), "0" (__old) \ : "memory"); \ break; \ } \ case __X86_CASE_Q: \ { \ volatile u64 *__ptr = (volatile u64 *)(ptr); \ asm volatile(lock "cmpxchgq %2,%1" \ : "=a" (__ret), "+m" (*__ptr) \ : "r" (__new), "0" (__old) \ : "memory"); \ break; \ } \ default: \ __cmpxchg_wrong_size(); \ } \ __ret; \ }) #define __cmpxchg(ptr, old, new, size) \ __raw_cmpxchg((ptr), (old), (new), (size), LOCK_PREFIX) #define __sync_cmpxchg(ptr, old, new, size) \ __raw_cmpxchg((ptr), (old), (new), (size), "lock; ") #define __cmpxchg_local(ptr, old, new, size) \ __raw_cmpxchg((ptr), (old), (new), (size), "") #ifdef CONFIG_X86_32 # include <asm/cmpxchg_32.h> #else # include <asm/cmpxchg_64.h> #endif #ifdef __HAVE_ARCH_CMPXCHG #define cmpxchg(ptr, old, new) \ __cmpxchg(ptr, old, new, sizeof(*(ptr))) #define sync_cmpxchg(ptr, old, new) \ __sync_cmpxchg(ptr, old, new, sizeof(*(ptr))) #define cmpxchg_local(ptr, old, new) \ __cmpxchg_local(ptr, old, new, sizeof(*(ptr))) #endif /* * xadd() adds "inc" to "*ptr" and atomically returns the previous * value of "*ptr". * * xadd() is locked when multiple CPUs are online * xadd_sync() is always locked * xadd_local() is never locked */ #define __xadd(ptr, inc, lock) __xchg_op((ptr), (inc), xadd, lock) #define xadd(ptr, inc) __xadd((ptr), (inc), LOCK_PREFIX) #define xadd_sync(ptr, inc) __xadd((ptr), (inc), "lock; ") #define xadd_local(ptr, inc) __xadd((ptr), (inc), "") #define __add(ptr, inc, lock) \ ({ \ __typeof__ (*(ptr)) __ret = (inc); \ switch (sizeof(*(ptr))) { \ case __X86_CASE_B: \ asm volatile (lock "addb %b1, %0\n" \ : "+m" (*(ptr)) : "qi" (inc) \ : "memory", "cc"); \ break; \ case __X86_CASE_W: \ asm volatile (lock "addw %w1, %0\n" \ : "+m" (*(ptr)) : "ri" (inc) \ : "memory", "cc"); \ break; \ case __X86_CASE_L: \ asm volatile (lock "addl %1, %0\n" \ : "+m" (*(ptr)) : "ri" (inc) \ : "memory", "cc"); \ break; \ case __X86_CASE_Q: \ asm volatile (lock "addq %1, %0\n" \ : "+m" (*(ptr)) : "ri" (inc) \ : "memory", "cc"); \ break; \ default: \ __add_wrong_size(); \ } \ __ret; \ }) /* * add_*() adds "inc" to "*ptr" * * __add() takes a lock prefix * add_smp() is locked when multiple CPUs are online * add_sync() is always locked */ #define add_smp(ptr, inc) __add((ptr), (inc), LOCK_PREFIX) #define add_sync(ptr, inc) __add((ptr), (inc), "lock; ") #define __cmpxchg_double(pfx, p1, p2, o1, o2, n1, n2) \ ({ \ bool __ret; \ __typeof__(*(p1)) __old1 = (o1), __new1 = (n1); \ __typeof__(*(p2)) __old2 = (o2), __new2 = (n2); \ BUILD_BUG_ON(sizeof(*(p1)) != sizeof(long)); \ BUILD_BUG_ON(sizeof(*(p2)) != sizeof(long)); \ VM_BUG_ON((unsigned long)(p1) % (2 * sizeof(long))); \ VM_BUG_ON((unsigned long)((p1) + 1) != (unsigned long)(p2)); \ asm volatile(pfx "cmpxchg%c4b %2; sete %0" \ : "=a" (__ret), "+d" (__old2), \ "+m" (*(p1)), "+m" (*(p2)) \ : "i" (2 * sizeof(long)), "a" (__old1), \ "b" (__new1), "c" (__new2)); \ __ret; \ }) #define cmpxchg_double(p1, p2, o1, o2, n1, n2) \ __cmpxchg_double(LOCK_PREFIX, p1, p2, o1, o2, n1, n2) #define cmpxchg_double_local(p1, p2, o1, o2, n1, n2) \ __cmpxchg_double(, p1, p2, o1, o2, n1, n2) #endif /* ASM_X86_CMPXCHG_H */
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