x86/cpu: Provide the full setup for getcpu() on x86-32

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setup_getcpu() configures two things:

  - it writes the current CPU & node information into MSR_TSC_AUX
  - it writes the same information as a GDT entry.

By using the "full" setup_getcpu() on i386 it is possible to read the CPU
information in userland via RDTSCP() or via LSL from the GDT.

Provide an GDT_ENTRY_CPUNODE for x86-32 and make the setup function
unconditionally available.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Roland Mainz <roland.mainz@nrubsig.org>
Link: https://lore.kernel.org/r/20221125094216.3663444-2-bigeasy@linutronix.de

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Sebastian Andrzej Siewior 2022-11-25 10:42:14 +01:00 • committed by Thomas Gleixner

parent 4c382d723e

commit 717cce3bdc

2 changed files with 5 additions and 7 deletions

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8

arch/x86/include/asm/segment.h

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4

arch/x86/kernel/cpu/common.c

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