> On Feb 2, 2019, at 09:17, Andy Lutomirski <[email protected]> wrote: > > On Fri, Feb 1, 2019 at 12:55 PM Chang S. Bae <[email protected]> wrote: >> >> + >> +/* >> + * CPU/node NR is loaded from the limit (size) field of a special segment >> + * descriptor entry in GDT. >> + */ >> +.macro LOAD_CPU_AND_NODE_SEG_LIMIT reg:req >> + movq $__CPUNODE_SEG, \reg >> + lsl \reg, \reg >> +.endm >> + > > Please put the alternative in here instead of in FIND_PERCPU_BASE.
I would like to apply your comment though, build errors will come up due to the __CPUNODE_SEG. So, still hoping the alternative line below is straightforward enough. Will send out a revision, that reflects all other comments, shortly. Chang > >> +/* >> + * Fetch the per-CPU GSBASE value for this processor and put it in @reg. >> + * We normally use %gs for accessing per-CPU data, but we are setting up >> + * %gs here and obviously can not use %gs itself to access per-CPU data. >> + */ >> +.macro FIND_PERCPU_BASE reg:req >> >> + ALTERNATIVE \ >> + "LOAD_CPU_AND_NODE_SEG_LIMIT \reg", \ >> + "RDPID \reg", \ >> + X86_FEATURE_RDPID >> + andq $VDSO_CPUNODE_MASK, \reg >> + movq __per_cpu_offset(, \reg, 8), \reg >> +.endm
