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 <gcosta@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Glauber de Oliveira Costa
Ingo Molnar
Родитель
62fe164c5b
Коммит
833d8469b1
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@ -202,4 +202,109 @@ extern void free_init_pages(char *what, unsigned long begin, unsigned long end);
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void default_idle(void);
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/*
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* Force strict CPU ordering.
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* And yes, this is required on UP too when we're talking
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* to devices.
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*/
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#ifdef CONFIG_X86_32
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/*
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* For now, "wmb()" doesn't actually do anything, as all
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* Intel CPU's follow what Intel calls a *Processor Order*,
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* in which all writes are seen in the program order even
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* outside the CPU.
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*
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* I expect future Intel CPU's to have a weaker ordering,
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* but I'd also expect them to finally get their act together
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* and add some real memory barriers if so.
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*
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* Some non intel clones support out of order store. wmb() ceases to be a
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* nop for these.
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*/
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#define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)
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#define rmb() alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2)
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#define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)
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#else
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#define mb() asm volatile("mfence":::"memory")
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#define rmb() asm volatile("lfence":::"memory")
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#define wmb() asm volatile("sfence" ::: "memory")
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#endif
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/**
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* read_barrier_depends - Flush all pending reads that subsequents reads
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* depend on.
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*
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* No data-dependent reads from memory-like regions are ever reordered
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* over this barrier. All reads preceding this primitive are guaranteed
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* to access memory (but not necessarily other CPUs' caches) before any
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* reads following this primitive that depend on the data return by
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* any of the preceding reads. This primitive is much lighter weight than
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* rmb() on most CPUs, and is never heavier weight than is
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* rmb().
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*
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* These ordering constraints are respected by both the local CPU
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* and the compiler.
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*
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* Ordering is not guaranteed by anything other than these primitives,
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* not even by data dependencies. See the documentation for
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* memory_barrier() for examples and URLs to more information.
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*
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* For example, the following code would force ordering (the initial
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* value of "a" is zero, "b" is one, and "p" is "&a"):
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*
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* <programlisting>
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* CPU 0 CPU 1
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*
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* b = 2;
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* memory_barrier();
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* p = &b; q = p;
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* read_barrier_depends();
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* d = *q;
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* </programlisting>
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*
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* because the read of "*q" depends on the read of "p" and these
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* two reads are separated by a read_barrier_depends(). However,
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* the following code, with the same initial values for "a" and "b":
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*
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* <programlisting>
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* CPU 0 CPU 1
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*
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* a = 2;
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* memory_barrier();
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* b = 3; y = b;
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* read_barrier_depends();
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* x = a;
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* </programlisting>
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*
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* does not enforce ordering, since there is no data dependency between
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* the read of "a" and the read of "b". Therefore, on some CPUs, such
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* as Alpha, "y" could be set to 3 and "x" to 0. Use rmb()
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* in cases like this where there are no data dependencies.
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**/
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#define read_barrier_depends() do { } while (0)
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#ifdef CONFIG_SMP
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#define smp_mb() mb()
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#ifdef CONFIG_X86_PPRO_FENCE
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# define smp_rmb() rmb()
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#else
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# define smp_rmb() barrier()
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#endif
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#ifdef CONFIG_X86_OOSTORE
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# define smp_wmb() wmb()
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#else
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# define smp_wmb() barrier()
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#endif
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#define smp_read_barrier_depends() read_barrier_depends()
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#define set_mb(var, value) do { (void) xchg(&var, value); } while (0)
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#else
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#define smp_mb() barrier()
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#define smp_rmb() barrier()
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#define smp_wmb() barrier()
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#define smp_read_barrier_depends() do { } while (0)
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#define set_mb(var, value) do { var = value; barrier(); } while (0)
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#endif
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#endif
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@ -36,105 +36,6 @@ extern struct task_struct * FASTCALL(__switch_to(struct task_struct *prev, struc
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#endif /* __KERNEL__ */
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/*
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* Force strict CPU ordering.
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* And yes, this is required on UP too when we're talking
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* to devices.
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*
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* For now, "wmb()" doesn't actually do anything, as all
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* Intel CPU's follow what Intel calls a *Processor Order*,
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* in which all writes are seen in the program order even
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* outside the CPU.
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*
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* I expect future Intel CPU's to have a weaker ordering,
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* but I'd also expect them to finally get their act together
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* and add some real memory barriers if so.
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*
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* Some non intel clones support out of order store. wmb() ceases to be a
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* nop for these.
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*/
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#define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)
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#define rmb() alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2)
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#define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)
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/**
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* read_barrier_depends - Flush all pending reads that subsequents reads
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* depend on.
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*
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* No data-dependent reads from memory-like regions are ever reordered
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* over this barrier. All reads preceding this primitive are guaranteed
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* to access memory (but not necessarily other CPUs' caches) before any
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* reads following this primitive that depend on the data return by
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* any of the preceding reads. This primitive is much lighter weight than
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* rmb() on most CPUs, and is never heavier weight than is
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* rmb().
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*
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* These ordering constraints are respected by both the local CPU
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* and the compiler.
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*
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* Ordering is not guaranteed by anything other than these primitives,
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* not even by data dependencies. See the documentation for
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* memory_barrier() for examples and URLs to more information.
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*
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* For example, the following code would force ordering (the initial
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* value of "a" is zero, "b" is one, and "p" is "&a"):
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*
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* <programlisting>
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* CPU 0 CPU 1
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*
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* b = 2;
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* memory_barrier();
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* p = &b; q = p;
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* read_barrier_depends();
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* d = *q;
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* </programlisting>
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*
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* because the read of "*q" depends on the read of "p" and these
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* two reads are separated by a read_barrier_depends(). However,
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* the following code, with the same initial values for "a" and "b":
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*
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* <programlisting>
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* CPU 0 CPU 1
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*
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* a = 2;
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* memory_barrier();
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* b = 3; y = b;
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* read_barrier_depends();
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* x = a;
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* </programlisting>
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*
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* does not enforce ordering, since there is no data dependency between
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* the read of "a" and the read of "b". Therefore, on some CPUs, such
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* as Alpha, "y" could be set to 3 and "x" to 0. Use rmb()
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* in cases like this where there are no data dependencies.
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**/
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#define read_barrier_depends() do { } while(0)
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#ifdef CONFIG_SMP
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#define smp_mb() mb()
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#ifdef CONFIG_X86_PPRO_FENCE
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# define smp_rmb() rmb()
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#else
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# define smp_rmb() barrier()
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#endif
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#ifdef CONFIG_X86_OOSTORE
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# define smp_wmb() wmb()
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#else
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# define smp_wmb() barrier()
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#endif
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#define smp_read_barrier_depends() read_barrier_depends()
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#define set_mb(var, value) do { (void) xchg(&var, value); } while (0)
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#else
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#define smp_mb() barrier()
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#define smp_rmb() barrier()
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#define smp_wmb() barrier()
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#define smp_read_barrier_depends() do { } while(0)
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#define set_mb(var, value) do { var = value; barrier(); } while (0)
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#endif
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#include <linux/irqflags.h>
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/*
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@ -48,31 +48,6 @@
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#endif /* __KERNEL__ */
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#ifdef CONFIG_SMP
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#define smp_mb() mb()
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#define smp_rmb() barrier()
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#define smp_wmb() barrier()
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#define smp_read_barrier_depends() do {} while(0)
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#else
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#define smp_mb() barrier()
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#define smp_rmb() barrier()
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#define smp_wmb() barrier()
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#define smp_read_barrier_depends() do {} while(0)
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#endif
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/*
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* Force strict CPU ordering.
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* And yes, this is required on UP too when we're talking
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* to devices.
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*/
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#define mb() asm volatile("mfence":::"memory")
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#define rmb() asm volatile("lfence":::"memory")
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#define wmb() asm volatile("sfence" ::: "memory")
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#define read_barrier_depends() do {} while(0)
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#define set_mb(var, value) do { (void) xchg(&var, value); } while (0)
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static inline unsigned long read_cr8(void)
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{
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unsigned long cr8;
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