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authorScott Wood <scottwood@freescale.com>2014-03-10 17:29:38 -0500
committerScott Wood <scottwood@freescale.com>2014-03-19 19:57:14 -0500
commit9d378dfac885f72b8b369d08fc61bef36e2f2dd1 (patch)
tree8790aa68cd0944e031b35eb63f5be14ec678be2d /arch/powerpc/kernel/exceptions-64e.S
parent82d86de25b9c99db546e17c6f7ebf9a691da557e (diff)
powerpc/booke64: Use SPRG7 for VDSO
Previously SPRG3 was marked for use by both VDSO and critical interrupts (though critical interrupts were not fully implemented). In commit 8b64a9dfb091f1eca8b7e58da82f1e7d1d5fe0ad ("powerpc/booke64: Use SPRG0/3 scratch for bolted TLB miss & crit int"), Mihai Caraman made an attempt to resolve this conflict by restoring the VDSO value early in the critical interrupt, but this has some issues: - It's incompatible with EXCEPTION_COMMON which restores r13 from the by-then-overwritten scratch (this cost me some debugging time). - It forces critical exceptions to be a special case handled differently from even machine check and debug level exceptions. - It didn't occur to me that it was possible to make this work at all (by doing a final "ld r13, PACA_EXCRIT+EX_R13(r13)") until after I made (most of) this patch. :-) It might be worth investigating using a load rather than SPRG on return from all exceptions (except TLB misses where the scratch never leaves the SPRG) -- it could save a few cycles. Until then, let's stick with SPRG for all exceptions. Since we cannot use SPRG4-7 for scratch without corrupting the state of a KVM guest, move VDSO to SPRG7 on book3e. Since neither SPRG4-7 nor critical interrupts exist on book3s, SPRG3 is still used for VDSO there. Signed-off-by: Scott Wood <scottwood@freescale.com> Cc: Mihai Caraman <mihai.caraman@freescale.com> Cc: Anton Blanchard <anton@samba.org> Cc: Paul Mackerras <paulus@samba.org> Cc: kvm-ppc@vger.kernel.org
Diffstat (limited to 'arch/powerpc/kernel/exceptions-64e.S')
-rw-r--r--arch/powerpc/kernel/exceptions-64e.S19
1 files changed, 2 insertions, 17 deletions
diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index 41380a424108..89e1133b0185 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -55,7 +55,6 @@
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 */ \
@@ -116,20 +115,6 @@
#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); \
- ld r11,PACA_SPRG3(r13); \
- mtspr SPRN_SPRG_CRIT_SCRATCH,r11;
-
/* Variants of the "addition" argument for the prolog
*/
#define PROLOG_ADDITION_NONE_GEN(n)
@@ -529,7 +514,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
mtcr r10
ld r10,PACA_EXCRIT+EX_R10(r13) /* restore registers */
ld r11,PACA_EXCRIT+EX_R11(r13)
- ld r13,PACA_EXCRIT+EX_R13(r13)
+ mfspr r13,SPRN_SPRG_CRIT_SCRATCH
rfci
/* Normal debug exception */
@@ -542,7 +527,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
/* Now we mash up things to make it look like we are coming on a
* normal exception
*/
- ld r15,PACA_EXCRIT+EX_R13(r13)
+ mfspr r15,SPRN_SPRG_CRIT_SCRATCH
mtspr SPRN_SPRG_GEN_SCRATCH,r15
mfspr r14,SPRN_DBSR
EXCEPTION_COMMON(0xd00, PACA_EXCRIT, INTS_DISABLE)