1/5
--
SUSE Labs, Novell Inc.
Changelog
* Make cmpxchg generally available on the i386 platform.
* Provide emulation of cmpxchg suitable for uniprocessor if
built and run on 386.
Signed-off-by: Christoph Lameter <[email protected]>
* Cut down patch and small style changes.
Signed-off-by: Nick Piggin <[email protected]>
Index: linux-2.6/arch/i386/kernel/cpu/intel.c
===================================================================
--- linux-2.6.orig/arch/i386/kernel/cpu/intel.c
+++ linux-2.6/arch/i386/kernel/cpu/intel.c
@@ -6,6 +6,7 @@
#include <linux/bitops.h>
#include <linux/smp.h>
#include <linux/thread_info.h>
+#include <linux/module.h>
#include <asm/processor.h>
#include <asm/msr.h>
@@ -264,5 +265,55 @@ __init int intel_cpu_init(void)
return 0;
}
+#ifndef CONFIG_X86_CMPXCHG
+unsigned long cmpxchg_386_u8(volatile void *ptr, u8 old, u8 new)
+{
+ u8 prev;
+ unsigned long flags;
+
+ /* Poor man's cmpxchg for 386. Unsuitable for SMP */
+ local_irq_save(flags);
+ prev = *(u8 *)ptr;
+ if (prev == old)
+ *(u8 *)ptr = new;
+ local_irq_restore(flags);
+ return prev;
+}
+
+EXPORT_SYMBOL(cmpxchg_386_u8);
+
+unsigned long cmpxchg_386_u16(volatile void *ptr, u16 old, u16 new)
+{
+ u16 prev;
+ unsigned long flags;
+
+ /* Poor man's cmpxchg for 386. Unsuitable for SMP */
+ local_irq_save(flags);
+ prev = *(u16 *)ptr;
+ if (prev == old)
+ *(u16 *)ptr = new;
+ local_irq_restore(flags);
+ return prev;
+}
+
+EXPORT_SYMBOL(cmpxchg_386_u16);
+
+unsigned long cmpxchg_386_u32(volatile void *ptr, u32 old, u32 new)
+{
+ u32 prev;
+ unsigned long flags;
+
+ /* Poor man's cmpxchg for 386. Unsuitable for SMP */
+ local_irq_save(flags);
+ prev = *(u32 *)ptr;
+ if (prev == old)
+ *(u32 *)ptr = new;
+ local_irq_restore(flags);
+ return prev;
+}
+
+EXPORT_SYMBOL(cmpxchg_386_u32);
+#endif
+
// arch_initcall(intel_cpu_init);
Index: linux-2.6/include/asm-i386/system.h
===================================================================
--- linux-2.6.orig/include/asm-i386/system.h
+++ linux-2.6/include/asm-i386/system.h
@@ -256,11 +256,6 @@ static inline unsigned long __xchg(unsig
* store NEW in MEM. Return the initial value in MEM. Success is
* indicated by comparing RETURN with OLD.
*/
-
-#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)
{
@@ -288,12 +283,53 @@ static inline unsigned long __cmpxchg(vo
return old;
}
+#ifdef CONFIG_X86_CMPXCHG
+#define __HAVE_ARCH_CMPXCHG 1
#define cmpxchg(ptr,o,n)\
- ((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
- (unsigned long)(n),sizeof(*(ptr))))
-
+ ((__typeof__(*(ptr)))__cmpxchg((ptr), (unsigned long)(o), \
+ (unsigned long)(n), sizeof(*(ptr))))
+
+#else
+
+/*
+ * Building a kernel capable running on 80386. It may be necessary to
+ * simulate the cmpxchg on the 80386 CPU. For that purpose we define
+ * a function for each of the sizes we support.
+ */
+
+extern unsigned long cmpxchg_386_u8(volatile void *, u8, u8);
+extern unsigned long cmpxchg_386_u16(volatile void *, u16, u16);
+extern unsigned long cmpxchg_386_u32(volatile void *, u32, u32);
+
+static inline unsigned long cmpxchg_386(volatile void *ptr, unsigned long old,
+ unsigned long new, int size)
+{
+ switch (size) {
+ case 1:
+ return cmpxchg_386_u8(ptr, old, new);
+ case 2:
+ return cmpxchg_386_u16(ptr, old, new);
+ case 4:
+ return cmpxchg_386_u32(ptr, old, new);
+ }
+ return old;
+}
+
+#define cmpxchg(ptr,o,n) \
+({ \
+ __typeof__(*(ptr)) __ret; \
+ if (likely(boot_cpu_data.x86 > 3)) \
+ __ret = __cmpxchg((ptr), (unsigned long)(o), \
+ (unsigned long)(n), sizeof(*(ptr))); \
+ else \
+ __ret = cmpxchg_386((ptr), (unsigned long)(o), \
+ (unsigned long)(n), sizeof(*(ptr))); \
+ __ret; \
+})
+#endif
+
#ifdef __KERNEL__
-struct alt_instr {
+struct alt_instr {
__u8 *instr; /* original instruction */
__u8 *replacement;
__u8 cpuid; /* cpuid bit set for replacement */
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
