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powerpc/booke64: Use SPRG0/3 scratch for bolted TLB miss & crit int

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Embedded.Hypervisor category defines GSPRG0..3 physical registers for guests.
Avoid SPRG4-7 usage as scratch in host exception handlers, otherwise guest
SPRG4-7 registers will be clobbered.
For bolted TLB miss exception handlers, which is the version currently
supported by KVM, use SPRN_SPRG_GEN_SCRATCH aka SPRG0 instead of
SPRN_SPRG_TLB_SCRATCH aka SPRG6. Keep using TLB PACA slots to fit in one
64-byte cache line.
For critical exception handlers use SPRG3 instead of SPRG7. Provide a routine
to store and restore user-visible SPRGs. This will be subsequently used
to restore VDSO information in SPRG3. Add EX_R13 to paca slots to free up
SPRG3 and change the critical exception epilog to use it.

Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Mihai Caraman 2012-08-06 03:27:07 +00:00 • committed by Benjamin Herrenschmidt
parent 79b5c8dbaa
commit 8b64a9dfb0
4 changed files with 23 additions and 8 deletions
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5
arch/powerpc/include/asm/exception-64e.h
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@ -46,8 +46,9 @@
#define EX_CR (1 * 8)
#define EX_R10 (2 * 8)
#define EX_R11 (3 * 8)
#define EX_R14 (4 * 8)
#define EX_R15 (5 * 8)
#define EX_R13 (4 * 8)
#define EX_R14 (5 * 8)
#define EX_R15 (6 * 8)
/*
* The TLB miss exception uses different slots.