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x86/cpu: Fix typos and improve the comments in sync_core()
- Fix typos. - Move the compiler barrier comment to the top, because it's valid for the whole function, not just the legacy branch. Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20200818053130.GA3161093@gmail.com Reviewed-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
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1 changed files with 8 additions and 8 deletions
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@ -47,16 +47,19 @@ static inline void iret_to_self(void)
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*
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*
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* b) Text was modified on a different CPU, may subsequently be
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* b) Text was modified on a different CPU, may subsequently be
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* executed on this CPU, and you want to make sure the new version
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* executed on this CPU, and you want to make sure the new version
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* gets executed. This generally means you're calling this in a IPI.
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* gets executed. This generally means you're calling this in an IPI.
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*
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*
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* If you're calling this for a different reason, you're probably doing
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* If you're calling this for a different reason, you're probably doing
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* it wrong.
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* it wrong.
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*
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* Like all of Linux's memory ordering operations, this is a
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* compiler barrier as well.
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*/
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*/
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static inline void sync_core(void)
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static inline void sync_core(void)
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{
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{
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/*
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/*
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* The SERIALIZE instruction is the most straightforward way to
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* The SERIALIZE instruction is the most straightforward way to
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* do this but it not universally available.
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* do this, but it is not universally available.
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*/
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*/
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if (static_cpu_has(X86_FEATURE_SERIALIZE)) {
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if (static_cpu_has(X86_FEATURE_SERIALIZE)) {
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serialize();
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serialize();
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@ -67,10 +70,10 @@ static inline void sync_core(void)
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* For all other processors, there are quite a few ways to do this.
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* For all other processors, there are quite a few ways to do this.
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* IRET-to-self is nice because it works on every CPU, at any CPL
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* IRET-to-self is nice because it works on every CPU, at any CPL
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* (so it's compatible with paravirtualization), and it never exits
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* (so it's compatible with paravirtualization), and it never exits
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* to a hypervisor. The only down sides are that it's a bit slow
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* to a hypervisor. The only downsides are that it's a bit slow
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* (it seems to be a bit more than 2x slower than the fastest
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* (it seems to be a bit more than 2x slower than the fastest
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* options) and that it unmasks NMIs. The "push %cs" is needed
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* options) and that it unmasks NMIs. The "push %cs" is needed,
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* because, in paravirtual environments, __KERNEL_CS may not be a
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* because in paravirtual environments __KERNEL_CS may not be a
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* valid CS value when we do IRET directly.
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* valid CS value when we do IRET directly.
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*
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*
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* In case NMI unmasking or performance ever becomes a problem,
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* In case NMI unmasking or performance ever becomes a problem,
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@ -81,9 +84,6 @@ static inline void sync_core(void)
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* CPUID is the conventional way, but it's nasty: it doesn't
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* CPUID is the conventional way, but it's nasty: it doesn't
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* exist on some 486-like CPUs, and it usually exits to a
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* exist on some 486-like CPUs, and it usually exits to a
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* hypervisor.
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* hypervisor.
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*
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* Like all of Linux's memory ordering operations, this is a
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* compiler barrier as well.
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*/
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*/
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iret_to_self();
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iret_to_self();
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}
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}
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