Use memory barriers defined by xen headers #28
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This gives us the necessary definitions for arm64. Those live in xen-barrier.h starting with 4.20, but we won't be able to use it for some time. Before this they live in xenctrl.h, but it pulls too much stuff. So this is a sync with the 4.20 headers contents. Since the code only uses mb, and no [rw]mb, the latter are not imported. The original macro name from the Xen header is preserved for easier future synchro, so this adjusts the callsites accordingly. Signed-off-by: Yann Dirson <yann.dirson@vates.tech>
| * back to those provided by the kernel */ | ||
| /* from <xen-barrier.h> in 4.20.0 */ | ||
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| #define xen_barrier() asm volatile ( "" : : : "memory") |
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Why is this added if it is not used?
Having said that, I think it might be preferable to simply include a copy of xen-barrier.h and #include it. It would be easier to keep up-to-date and mean less tat in this file.
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This gives us the necessary definitions for arm64.
Those live in xen-barrier.h starting with 4.20, but we won't be able to use it for some time. Before this they live in xenctrl.h, but it pulls too much stuff. So this is a sync with the 4.20 headers contents.
Since the code only uses mb, and no [rw]mb, the latter are not imported. The original macro name from the Xen header is preserved for easier future synchro, so this adjusts the callsites accordingly.