powerpc/booke64: Use SPRG0/3 scratch for bolted TLB miss & crit int
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>
diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index 83c20e8..7476b0a 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -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 @@
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 @@
/* 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)