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Chang S. Bae authored
GSBASE is used to find per-CPU data in the kernel. But when GSBASE is unknown, the per-CPU base can be found from the per_cpu_offset table with a CPU NR. The CPU NR is extracted from the limit field of the CPUNODE entry in GDT, or by the RDPID instruction. This is a prerequisite for using FSGSBASE in the low level entry code. Also, add the GAS-compatible RDPID macro as binutils 2.23 do not support it. Support is added in version 2.27. [ tglx: Massaged changelog ] Suggested-by:
H. Peter Anvin <hpa@zytor.com> Signed-off-by:
Chang S. Bae <chang.seok.bae@intel.com> Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Signed-off-by:
Sasha Levin <sashal@kernel.org> Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/1557309753-24073-12-git-send-email-chang.seok.bae@intel.com Link: https://lkml.kernel.org/r/20200528201402.1708239-11-sashal@kernel.org
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