[Xen-changelog] Make SMP alternatives work under xenolinux rather than just native,

[Xen patchbot -unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User sos22@xxxxxxxxxxxxxxxxxxxx
# Node ID 5ffe3f16aa52a817e5656c24e9bea9a7033b3737
# Parent  ea6d9f29dff5d429c0a7cb6c381628e6f2bb38e1
Make SMP alternatives work under xenolinux rather than just native,
since part of it seems to have gotten lost.

Signed-off-by: Steven Smith, sos22@xxxxxxxxx

diff -r ea6d9f29dff5 -r 5ffe3f16aa52 
linux-2.6-xen-sparse/include/asm-xen/asm-i386/spinlock.h
--- a/linux-2.6-xen-sparse/include/asm-xen/asm-i386/spinlock.h  Mon Oct 31 
16:07:14 2005
+++ b/linux-2.6-xen-sparse/include/asm-xen/asm-i386/spinlock.h  Tue Nov  1 
12:38:20 2005
@@ -6,6 +6,7 @@
 #include <asm/page.h>
 #include <linux/config.h>
 #include <linux/compiler.h>
+#include <asm/smp_alt.h>
 
 asmlinkage int printk(const char * fmt, ...)
        __attribute__ ((format (printf, 1, 2)));
@@ -47,8 +48,9 @@
 #define spin_unlock_wait(x)    do { barrier(); } while(spin_is_locked(x))
 
 #define spin_lock_string \
-       "\n1:\t" \
-       "lock ; decb %0\n\t" \
+        "1:\n" \
+       LOCK \
+       "decb %0\n\t" \
        "jns 3f\n" \
        "2:\t" \
        "rep;nop\n\t" \
@@ -58,8 +60,9 @@
        "3:\n\t"
 
 #define spin_lock_string_flags \
-       "\n1:\t" \
-       "lock ; decb %0\n\t" \
+        "1:\n" \
+       LOCK \
+       "decb %0\n\t" \
        "jns 4f\n\t" \
        "2:\t" \
        "testl $0x200, %1\n\t" \
@@ -121,10 +124,34 @@
 static inline int _raw_spin_trylock(spinlock_t *lock)
 {
        char oldval;
-       __asm__ __volatile__(
-               "xchgb %b0,%1"
+#ifdef CONFIG_SMP_ALTERNATIVES
+       __asm__ __volatile__(
+               "1:movb %1,%b0\n"
+               "movb $0,%1\n"
+               "2:"
+               ".section __smp_alternatives,\"a\"\n"
+               ".long 1b\n"
+               ".long 3f\n"
+               ".previous\n"
+               ".section __smp_replacements,\"a\"\n"
+               "3: .byte 2b - 1b\n"
+               ".byte 5f-4f\n"
+               ".byte 0\n"
+               ".byte 6f-5f\n"
+               ".byte -1\n"
+               "4: xchgb %b0,%1\n"
+               "5: movb %1,%b0\n"
+               "movb $0,%1\n"
+               "6:\n"
+               ".previous\n"
                :"=q" (oldval), "=m" (lock->slock)
                :"0" (0) : "memory");
+#else
+       __asm__ __volatile__(
+               "xchgb %b0,%1\n"
+               :"=q" (oldval), "=m" (lock->slock)
+               :"0" (0) : "memory");
+#endif
        return oldval > 0;
 }
 
@@ -225,8 +252,8 @@
        __build_write_lock(rw, "__write_lock_failed");
 }
 
-#define _raw_read_unlock(rw)           asm volatile("lock ; incl %0" :"=m" 
((rw)->lock) : : "memory")
-#define _raw_write_unlock(rw)  asm volatile("lock ; addl $" RW_LOCK_BIAS_STR 
",%0":"=m" ((rw)->lock) : : "memory")
+#define _raw_read_unlock(rw)   asm volatile(LOCK "incl %0" :"=m" ((rw)->lock) 
: : "memory")
+#define _raw_write_unlock(rw)  asm volatile(LOCK "addl $" RW_LOCK_BIAS_STR 
",%0":"=m" ((rw)->lock) : : "memory")
 
 static inline int _raw_read_trylock(rwlock_t *lock)
 {

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