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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
View File

@ -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.

5
arch/powerpc/include/asm/reg.h
View File

@ -761,7 +761,8 @@
* 64-bit embedded
* - SPRG0 generic exception scratch
* - SPRG2 TLB exception stack
* - SPRG3 CPU and NUMA node for VDSO getcpu (user visible)
* - SPRG3 critical exception scratch and
* CPU and NUMA node for VDSO getcpu (user visible)
* - SPRG4 unused (user visible)
* - SPRG6 TLB miss scratch (user visible, sorry !)
* - SPRG7 critical exception scratch
@ -858,7 +859,7 @@
#ifdef CONFIG_PPC_BOOK3E_64
#define SPRN_SPRG_MC_SCRATCH SPRN_SPRG8
#define SPRN_SPRG_CRIT_SCRATCH SPRN_SPRG7
#define SPRN_SPRG_CRIT_SCRATCH SPRN_SPRG3
#define SPRN_SPRG_DBG_SCRATCH SPRN_SPRG9
#define SPRN_SPRG_TLB_EXFRAME SPRN_SPRG2
#define SPRN_SPRG_TLB_SCRATCH SPRN_SPRG6

17
arch/powerpc/kernel/exceptions-64e.S
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@ -42,6 +42,7 @@
mfspr r13,SPRN_SPRG_PACA; /* get PACA */ \
std r10,PACA_EX##type+EX_R10(r13); \
std r11,PACA_EX##type+EX_R11(r13); \
PROLOG_STORE_RESTORE_SCRATCH_##type; \
mfcr r10; /* save CR */ \
mfspr r11,SPRN_##type##_SRR1;/* what are we coming from */ \
DO_KVM intnum,SPRN_##type##_SRR1; /* KVM hook */ \
@ -99,6 +100,18 @@
#define GDBELL_EXCEPTION_PROLOG(n, intnum, addition) \
EXCEPTION_PROLOG(n, intnum, GDBELL, addition##_GDBELL(n))
/*
* Store user-visible scratch in PACA exception slots and restore proper value
*/
#define PROLOG_STORE_RESTORE_SCRATCH_GEN
#define PROLOG_STORE_RESTORE_SCRATCH_GDBELL
#define PROLOG_STORE_RESTORE_SCRATCH_DBG
#define PROLOG_STORE_RESTORE_SCRATCH_MC
#define PROLOG_STORE_RESTORE_SCRATCH_CRIT \
mfspr r10,SPRN_SPRG_CRIT_SCRATCH; /* get r13 */ \
std r10,PACA_EXCRIT+EX_R13(r13)
/* Variants of the "addition" argument for the prolog
*/
#define PROLOG_ADDITION_NONE_GEN(n)
@ -454,7 +467,7 @@ interrupt_end_book3e:
mtcr r10
ld r10,PACA_EXCRIT+EX_R10(r13) /* restore registers */
ld r11,PACA_EXCRIT+EX_R11(r13)
mfspr r13,SPRN_SPRG_CRIT_SCRATCH
ld r13,PACA_EXCRIT+EX_R13(r13)
rfci
/* Normal debug exception */
@ -467,7 +480,7 @@ interrupt_end_book3e:
/* Now we mash up things to make it look like we are coming on a
* normal exception
*/
mfspr r15,SPRN_SPRG_CRIT_SCRATCH
ld r15,PACA_EXCRIT+EX_R13(r13)
mtspr SPRN_SPRG_GEN_SCRATCH,r15
mfspr r14,SPRN_DBSR
EXCEPTION_COMMON(0xd00, PACA_EXCRIT, INTS_DISABLE)

4
arch/powerpc/mm/tlb_low_64e.S
View File

@ -40,7 +40,7 @@
**********************************************************************/
.macro tlb_prolog_bolted intnum addr
mtspr SPRN_SPRG_TLB_SCRATCH,r13
mtspr SPRN_SPRG_GEN_SCRATCH,r13
mfspr r13,SPRN_SPRG_PACA
std r10,PACA_EXTLB+EX_TLB_R10(r13)
mfcr r10
@ -69,7 +69,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_EMB_HV)
ld r15,PACA_EXTLB+EX_TLB_R15(r13)
TLB_MISS_RESTORE_STATS_BOLTED
ld r16,PACA_EXTLB+EX_TLB_R16(r13)
mfspr r13,SPRN_SPRG_TLB_SCRATCH
mfspr r13,SPRN_SPRG_GEN_SCRATCH
.endm
/* Data TLB miss */