Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=833d8469b102365f427f7791e79ec1843ff5f164
Commit:     833d8469b102365f427f7791e79ec1843ff5f164
Parent:     62fe164c5b036f4bdb19fbfb8f18a75631e67eee
Author:     Glauber de Oliveira Costa <[EMAIL PROTECTED]>
AuthorDate: Wed Jan 30 13:31:08 2008 +0100
Committer:  Ingo Molnar <[EMAIL PROTECTED]>
CommitDate: Wed Jan 30 13:31:08 2008 +0100

    x86: unify smp parts of system.h
    
    The memory barrier parts of system.h are not very different between
    i386 and x86_64, the main difference being the availability of
    instructions, which we handle with the use of ifdefs.
    
    They are consolidated in system.h file, and then removed from
    the arch-specific headers.
    
    Signed-off-by: Glauber de Oliveira Costa <[EMAIL PROTECTED]>
    Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
    Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
---
 include/asm-x86/system.h    |  105 +++++++++++++++++++++++
 include/asm-x86/system_32.h |  191 ++++++++++--------------------------------
 include/asm-x86/system_64.h |   25 ------
 3 files changed, 151 insertions(+), 170 deletions(-)

diff --git a/include/asm-x86/system.h b/include/asm-x86/system.h
index 01ba1f8..4c15eb1 100644
--- a/include/asm-x86/system.h
+++ b/include/asm-x86/system.h
@@ -202,4 +202,109 @@ extern void free_init_pages(char *what, unsigned long 
begin, unsigned long end);
 
 void default_idle(void);
 
+/*
+ * Force strict CPU ordering.
+ * And yes, this is required on UP too when we're talking
+ * to devices.
+ */
+#ifdef CONFIG_X86_32
+/*
+ * For now, "wmb()" doesn't actually do anything, as all
+ * Intel CPU's follow what Intel calls a *Processor Order*,
+ * in which all writes are seen in the program order even
+ * outside the CPU.
+ *
+ * I expect future Intel CPU's to have a weaker ordering,
+ * but I'd also expect them to finally get their act together
+ * and add some real memory barriers if so.
+ *
+ * Some non intel clones support out of order store. wmb() ceases to be a
+ * nop for these.
+ */
+#define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)
+#define rmb() alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2)
+#define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)
+#else
+#define mb()   asm volatile("mfence":::"memory")
+#define rmb()  asm volatile("lfence":::"memory")
+#define wmb()  asm volatile("sfence" ::: "memory")
+#endif
+
+/**
+ * read_barrier_depends - Flush all pending reads that subsequents reads
+ * depend on.
+ *
+ * No data-dependent reads from memory-like regions are ever reordered
+ * over this barrier.  All reads preceding this primitive are guaranteed
+ * to access memory (but not necessarily other CPUs' caches) before any
+ * reads following this primitive that depend on the data return by
+ * any of the preceding reads.  This primitive is much lighter weight than
+ * rmb() on most CPUs, and is never heavier weight than is
+ * rmb().
+ *
+ * These ordering constraints are respected by both the local CPU
+ * and the compiler.
+ *
+ * Ordering is not guaranteed by anything other than these primitives,
+ * not even by data dependencies.  See the documentation for
+ * memory_barrier() for examples and URLs to more information.
+ *
+ * For example, the following code would force ordering (the initial
+ * value of "a" is zero, "b" is one, and "p" is "&a"):
+ *
+ * <programlisting>
+ *     CPU 0                           CPU 1
+ *
+ *     b = 2;
+ *     memory_barrier();
+ *     p = &b;                         q = p;
+ *                                     read_barrier_depends();
+ *                                     d = *q;
+ * </programlisting>
+ *
+ * because the read of "*q" depends on the read of "p" and these
+ * two reads are separated by a read_barrier_depends().  However,
+ * the following code, with the same initial values for "a" and "b":
+ *
+ * <programlisting>
+ *     CPU 0                           CPU 1
+ *
+ *     a = 2;
+ *     memory_barrier();
+ *     b = 3;                          y = b;
+ *                                     read_barrier_depends();
+ *                                     x = a;
+ * </programlisting>
+ *
+ * does not enforce ordering, since there is no data dependency between
+ * the read of "a" and the read of "b".  Therefore, on some CPUs, such
+ * as Alpha, "y" could be set to 3 and "x" to 0.  Use rmb()
+ * in cases like this where there are no data dependencies.
+ **/
+
+#define read_barrier_depends() do { } while (0)
+
+#ifdef CONFIG_SMP
+#define smp_mb()       mb()
+#ifdef CONFIG_X86_PPRO_FENCE
+# define smp_rmb()     rmb()
+#else
+# define smp_rmb()     barrier()
+#endif
+#ifdef CONFIG_X86_OOSTORE
+# define smp_wmb()     wmb()
+#else
+# define smp_wmb()     barrier()
+#endif
+#define smp_read_barrier_depends()     read_barrier_depends()
+#define set_mb(var, value) do { (void) xchg(&var, value); } while (0)
+#else
+#define smp_mb()       barrier()
+#define smp_rmb()      barrier()
+#define smp_wmb()      barrier()
+#define smp_read_barrier_depends()     do { } while (0)
+#define set_mb(var, value) do { var = value; barrier(); } while (0)
+#endif
+
+
 #endif
diff --git a/include/asm-x86/system_32.h b/include/asm-x86/system_32.h
dissimilarity index 70%
index c055682..7da0716 100644
--- a/include/asm-x86/system_32.h
+++ b/include/asm-x86/system_32.h
@@ -1,145 +1,46 @@
-#ifndef __ASM_SYSTEM_H
-#define __ASM_SYSTEM_H
-
-#include <asm/segment.h>
-#include <asm/cpufeature.h>
-#include <asm/cmpxchg.h>
-
-#ifdef __KERNEL__
-#define AT_VECTOR_SIZE_ARCH 2 /* entries in ARCH_DLINFO */
-
-struct task_struct;    /* one of the stranger aspects of C forward 
declarations.. */
-extern struct task_struct * FASTCALL(__switch_to(struct task_struct *prev, 
struct task_struct *next));
-
-/*
- * Saving eflags is important. It switches not only IOPL between tasks,
- * it also protects other tasks from NT leaking through sysenter etc.
- */
-#define switch_to(prev,next,last) do {                                 \
-       unsigned long esi,edi;                                          \
-       asm volatile("pushfl\n\t"               /* Save flags */        \
-                    "pushl %%ebp\n\t"                                  \
-                    "movl %%esp,%0\n\t"        /* save ESP */          \
-                    "movl %5,%%esp\n\t"        /* restore ESP */       \
-                    "movl $1f,%1\n\t"          /* save EIP */          \
-                    "pushl %6\n\t"             /* restore EIP */       \
-                    "jmp __switch_to\n"                                \
-                    "1:\t"                                             \
-                    "popl %%ebp\n\t"                                   \
-                    "popfl"                                            \
-                    :"=m" (prev->thread.sp),"=m" (prev->thread.ip),    \
-                     "=a" (last),"=S" (esi),"=D" (edi)                 \
-                    :"m" (next->thread.sp),"m" (next->thread.ip),      \
-                     "2" (prev), "d" (next));                          \
-} while (0)
-
-#endif /* __KERNEL__ */
-
-
-/*
- * Force strict CPU ordering.
- * And yes, this is required on UP too when we're talking
- * to devices.
- *
- * For now, "wmb()" doesn't actually do anything, as all
- * Intel CPU's follow what Intel calls a *Processor Order*,
- * in which all writes are seen in the program order even
- * outside the CPU.
- *
- * I expect future Intel CPU's to have a weaker ordering,
- * but I'd also expect them to finally get their act together
- * and add some real memory barriers if so.
- *
- * Some non intel clones support out of order store. wmb() ceases to be a
- * nop for these.
- */
- 
-
-#define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)
-#define rmb() alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2)
-#define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)
-
-/**
- * read_barrier_depends - Flush all pending reads that subsequents reads
- * depend on.
- *
- * No data-dependent reads from memory-like regions are ever reordered
- * over this barrier.  All reads preceding this primitive are guaranteed
- * to access memory (but not necessarily other CPUs' caches) before any
- * reads following this primitive that depend on the data return by
- * any of the preceding reads.  This primitive is much lighter weight than
- * rmb() on most CPUs, and is never heavier weight than is
- * rmb().
- *
- * These ordering constraints are respected by both the local CPU
- * and the compiler.
- *
- * Ordering is not guaranteed by anything other than these primitives,
- * not even by data dependencies.  See the documentation for
- * memory_barrier() for examples and URLs to more information.
- *
- * For example, the following code would force ordering (the initial
- * value of "a" is zero, "b" is one, and "p" is "&a"):
- *
- * <programlisting>
- *     CPU 0                           CPU 1
- *
- *     b = 2;
- *     memory_barrier();
- *     p = &b;                         q = p;
- *                                     read_barrier_depends();
- *                                     d = *q;
- * </programlisting>
- *
- * because the read of "*q" depends on the read of "p" and these
- * two reads are separated by a read_barrier_depends().  However,
- * the following code, with the same initial values for "a" and "b":
- *
- * <programlisting>
- *     CPU 0                           CPU 1
- *
- *     a = 2;
- *     memory_barrier();
- *     b = 3;                          y = b;
- *                                     read_barrier_depends();
- *                                     x = a;
- * </programlisting>
- *
- * does not enforce ordering, since there is no data dependency between
- * the read of "a" and the read of "b".  Therefore, on some CPUs, such
- * as Alpha, "y" could be set to 3 and "x" to 0.  Use rmb()
- * in cases like this where there are no data dependencies.
- **/
-
-#define read_barrier_depends() do { } while(0)
-
-#ifdef CONFIG_SMP
-#define smp_mb()       mb()
-#ifdef CONFIG_X86_PPRO_FENCE
-# define smp_rmb()     rmb()
-#else
-# define smp_rmb()     barrier()
-#endif
-#ifdef CONFIG_X86_OOSTORE
-# define smp_wmb()     wmb()
-#else
-# define smp_wmb()     barrier()
-#endif
-#define smp_read_barrier_depends()     read_barrier_depends()
-#define set_mb(var, value) do { (void) xchg(&var, value); } while (0)
-#else
-#define smp_mb()       barrier()
-#define smp_rmb()      barrier()
-#define smp_wmb()      barrier()
-#define smp_read_barrier_depends()     do { } while(0)
-#define set_mb(var, value) do { var = value; barrier(); } while (0)
-#endif
-
-#include <linux/irqflags.h>
-
-/*
- * disable hlt during certain critical i/o operations
- */
-#define HAVE_DISABLE_HLT
-
-#endif
+#ifndef __ASM_SYSTEM_H
+#define __ASM_SYSTEM_H
+
+#include <asm/segment.h>
+#include <asm/cpufeature.h>
+#include <asm/cmpxchg.h>
+
+#ifdef __KERNEL__
+#define AT_VECTOR_SIZE_ARCH 2 /* entries in ARCH_DLINFO */
+
+struct task_struct;    /* one of the stranger aspects of C forward 
declarations.. */
+extern struct task_struct * FASTCALL(__switch_to(struct task_struct *prev, 
struct task_struct *next));
+
+/*
+ * Saving eflags is important. It switches not only IOPL between tasks,
+ * it also protects other tasks from NT leaking through sysenter etc.
+ */
+#define switch_to(prev,next,last) do {                                 \
+       unsigned long esi,edi;                                          \
+       asm volatile("pushfl\n\t"               /* Save flags */        \
+                    "pushl %%ebp\n\t"                                  \
+                    "movl %%esp,%0\n\t"        /* save ESP */          \
+                    "movl %5,%%esp\n\t"        /* restore ESP */       \
+                    "movl $1f,%1\n\t"          /* save EIP */          \
+                    "pushl %6\n\t"             /* restore EIP */       \
+                    "jmp __switch_to\n"                                \
+                    "1:\t"                                             \
+                    "popl %%ebp\n\t"                                   \
+                    "popfl"                                            \
+                    :"=m" (prev->thread.sp),"=m" (prev->thread.ip),    \
+                     "=a" (last),"=S" (esi),"=D" (edi)                 \
+                    :"m" (next->thread.sp),"m" (next->thread.ip),      \
+                     "2" (prev), "d" (next));                          \
+} while (0)
+
+#endif /* __KERNEL__ */
+
+
+#include <linux/irqflags.h>
+
+/*
+ * disable hlt during certain critical i/o operations
+ */
+#define HAVE_DISABLE_HLT
+
+#endif
diff --git a/include/asm-x86/system_64.h b/include/asm-x86/system_64.h
index 560470e..9def35e 100644
--- a/include/asm-x86/system_64.h
+++ b/include/asm-x86/system_64.h
@@ -48,31 +48,6 @@
     
 #endif /* __KERNEL__ */
 
-#ifdef CONFIG_SMP
-#define smp_mb()       mb()
-#define smp_rmb()      barrier()
-#define smp_wmb()      barrier()
-#define smp_read_barrier_depends()     do {} while(0)
-#else
-#define smp_mb()       barrier()
-#define smp_rmb()      barrier()
-#define smp_wmb()      barrier()
-#define smp_read_barrier_depends()     do {} while(0)
-#endif
-
-    
-/*
- * Force strict CPU ordering.
- * And yes, this is required on UP too when we're talking
- * to devices.
- */
-#define mb()   asm volatile("mfence":::"memory")
-#define rmb()  asm volatile("lfence":::"memory")
-#define wmb()  asm volatile("sfence" ::: "memory")
-
-#define read_barrier_depends() do {} while(0)
-#define set_mb(var, value) do { (void) xchg(&var, value); } while (0)
-
 static inline unsigned long read_cr8(void)
 {
        unsigned long cr8;
-
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