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authorThomas Petazzoni <thomas.petazzoni@free-electrons.com>2008-08-18 12:33:21 +0200
committerIngo Molnar <mingo@elte.hu>2008-08-18 16:05:47 +0200
commit774400a3ba23b63f4de39e67ce6c4e48935809dc (patch)
treec5386a1c3151d97971f48c75a3c861abbac1105f /arch/x86/kernel/cpu/cmpxchg.c
parent8bfcb3960fde049b863266dab8c3617bb5a541aa (diff)
x86: move cmpxchg fallbacks to a generic place
arch/x86/kernel/cpu/intel.c defines a few fallback functions (cmpxchg_*()) that are used when the CPU doesn't support cmpxchg and/or cmpxchg64 natively. However, while defined in an Intel-specific file, these functions are also used for CPUs from other vendors when they don't support cmpxchg and/or cmpxchg64. This breaks the compilation when support for Intel CPUs is disabled. This patch moves these functions to a new arch/x86/kernel/cpu/cmpxchg.c file, unconditionally compiled when X86_32 is enabled. Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> Cc: michael@free-electrons.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/cpu/cmpxchg.c')
-rw-r--r--arch/x86/kernel/cpu/cmpxchg.c72
1 files changed, 72 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/cmpxchg.c b/arch/x86/kernel/cpu/cmpxchg.c
new file mode 100644
index 00000000000..2056ccf572c
--- /dev/null
+++ b/arch/x86/kernel/cpu/cmpxchg.c
@@ -0,0 +1,72 @@
+/*
+ * cmpxchg*() fallbacks for CPU not supporting these instructions
+ */
+
+#include <linux/kernel.h>
+#include <linux/smp.h>
+#include <linux/module.h>
+
+#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
+
+#ifndef CONFIG_X86_CMPXCHG64
+unsigned long long cmpxchg_486_u64(volatile void *ptr, u64 old, u64 new)
+{
+ u64 prev;
+ unsigned long flags;
+
+ /* Poor man's cmpxchg8b for 386 and 486. Unsuitable for SMP */
+ local_irq_save(flags);
+ prev = *(u64 *)ptr;
+ if (prev == old)
+ *(u64 *)ptr = new;
+ local_irq_restore(flags);
+ return prev;
+}
+EXPORT_SYMBOL(cmpxchg_486_u64);
+#endif
+