PER_CPU_VAR(kernel_stack) was set up in a way where it points
five stack slots below the top of stack.
Presumably, it was done to avoid one "sub $5*8,%rsp"
in syscall/sysenter code paths, where iret frame needs to be
created by hand.
Ironically, none of them benefit from this optimization,
since
PER_CPU_VAR(kernel_stack) was set up in a way where it points
five stack slots below the top of stack.
Presumably, it was done to avoid one sub $5*8,%rsp
in syscall/sysenter code paths, where iret frame needs to be
created by hand.
Ironically, none of them benefit from this optimization,
since
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