>>> Dave Jones <[email protected]> 10.09.05 02:30:38 >>> >On Fri, Sep 09, 2005 at 05:06:56PM -0700, Andrew Morton wrote: > > > - cmpxchg8b gets disabled when the minimum specified hardware architectur > > doesn't support it (like was already happening for the byte, word, and > > long ones). > > > > +config X86_CMPXCHG64 > > + bool > > + depends on !M386 && !M486 && !MCYRIXIII && !MGEODEGX1 > > + default y > >This is wrong. All the Winchip/CyrixIII CPUs do indeed have cx8. >Though cpuid will report that it's missing until We explicitly enable >it in init_c3(). Whilst it's "disabled" however, the instruction does >run perfectly fine. This was done because Win NT wouldn't boot if it >found a non Intel CPU which had cx8 iirc. > >I'm not familiar with the Geode enough to answer definitively. >Alan seems to be the Geode-guru, and may still have datasheets for that. Resubmitting adjusted patch (taking into account also Alan's later response). (Note: Patch also attached because the inline version is certain to get line wrapped.) This adjusts i386's cmpxchg patterns so that - for word and long cmpxchg-es the compiler can utilize all possible registers - cmpxchg8b gets disabled when the minimum specified hardware architectur doesn't support it (like was already happening for the byte, word, and long ones). Signed-off-by: Jan Beulich <[email protected]> diff -Npru 2.6.13/arch/i386/Kconfig 2.6.13-i386-cmpxchg/arch/i386/Kconfig --- 2.6.13/arch/i386/Kconfig 2005-08-29 01:41:01.000000000 +0200 +++ 2.6.13-i386-cmpxchg/arch/i386/Kconfig 2005-09-01 11:45:29.000000000 +0200 @@ -412,6 +412,11 @@ config X86_POPAD_OK depends on !M386 default y +config X86_CMPXCHG64 + bool + depends on !M386 && !M486 + default y + config X86_ALIGNMENT_16 bool depends on MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCYRIXIII || X86_ELAN || MK6 || M586MMX || M586TSC || M586 || M486 || MVIAC3_2 || MGEODEGX1 diff -Npru 2.6.13/include/asm-i386/system.h 2.6.13-i386-cmpxchg/include/asm-i386/system.h --- 2.6.13/include/asm-i386/system.h 2005-08-29 01:41:01.000000000 +0200 +++ 2.6.13-i386-cmpxchg/include/asm-i386/system.h 2005-09-07 11:37:25.000000000 +0200 @@ -149,6 +149,8 @@ struct __xchg_dummy { unsigned long a[10 #define __xg(x) ((struct __xchg_dummy *)(x)) +#ifdef CONFIG_X86_CMPXCHG64 + /* * The semantics of XCHGCMP8B are a bit strange, this is why * there is a loop and the loading of %%eax and %%edx has to @@ -203,6 +205,8 @@ static inline void __set_64bit_var (unsi __set_64bit(ptr, (unsigned int)(value), (unsigned int)((value)>>32ULL) ) : \ __set_64bit(ptr, ll_low(value), ll_high(value)) ) +#endif + /* * Note: no "lock" prefix even on SMP: xchg always implies lock anyway * Note 2: xchg has side effect, so that attribute volatile is necessary, @@ -241,7 +245,6 @@ static inline unsigned long __xchg(unsig #ifdef CONFIG_X86_CMPXCHG #define __HAVE_ARCH_CMPXCHG 1 -#endif static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size) @@ -257,13 +260,13 @@ static inline unsigned long __cmpxchg(vo case 2: __asm__ __volatile__(LOCK_PREFIX "cmpxchgw %w1,%2" : "=a"(prev) - : "q"(new), "m"(*__xg(ptr)), "0"(old) + : "r"(new), "m"(*__xg(ptr)), "0"(old) : "memory"); return prev; case 4: __asm__ __volatile__(LOCK_PREFIX "cmpxchgl %1,%2" : "=a"(prev) - : "q"(new), "m"(*__xg(ptr)), "0"(old) + : "r"(new), "m"(*__xg(ptr)), "0"(old) : "memory"); return prev; } @@ -273,6 +276,30 @@ static inline unsigned long __cmpxchg(vo #define cmpxchg(ptr,o,n)\ ((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\ (unsigned long)(n),sizeof(*(ptr)))) + +#endif + +#ifdef CONFIG_X86_CMPXCHG64 + +static inline unsigned long long __cmpxchg64(volatile void *ptr, unsigned long long old, + unsigned long long new) +{ + unsigned long long prev; + __asm__ __volatile__(LOCK_PREFIX "cmpxchg8b %3" + : "=A"(prev) + : "b"((unsigned long)new), + "c"((unsigned long)(new >> 32)), + "m"(*__xg(ptr)), + "0"(old) + : "memory"); + return prev; +} + +#define cmpxchg64(ptr,o,n)\ + ((__typeof__(*(ptr)))__cmpxchg64((ptr),(unsigned long long)(o),\ + (unsigned long long)(n))) + +#endif #ifdef __KERNEL__ struct alt_instr {
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