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
diff --git a/arch/powerpc/include/asm/exception-64e.h b/arch/powerpc/include/asm/exception-64e.h
index 51fa43e..e73452f 100644
--- a/arch/powerpc/include/asm/exception-64e.h
+++ b/arch/powerpc/include/asm/exception-64e.h
@@ -46,9 +46,8 @@
#define EX_CR (1 * 8)
#define EX_R10 (2 * 8)
#define EX_R11 (3 * 8)
-#define EX_R13 (4 * 8)
-#define EX_R14 (5 * 8)
-#define EX_R15 (6 * 8)
+#define EX_R14 (4 * 8)
+#define EX_R15 (5 * 8)
/*
* The TLB miss exception uses different slots.
diff --git a/arch/powerpc/include/asm/kvm_booke_hv_asm.h b/arch/powerpc/include/asm/kvm_booke_hv_asm.h
index 3a79f53..c3e3fd5 100644
--- a/arch/powerpc/include/asm/kvm_booke_hv_asm.h
+++ b/arch/powerpc/include/asm/kvm_booke_hv_asm.h
@@ -36,20 +36,13 @@
* *(r8 + GPR11) = saved r11
*
* 64-bit host
- * Expected inputs (GEN/GDBELL/DBG/MC exception types):
+ * Expected inputs (GEN/GDBELL/DBG/CRIT/MC exception types):
* r10 = saved CR
* r13 = PACA_POINTER
* *(r13 + PACA_EX##type + EX_R10) = saved r10
* *(r13 + PACA_EX##type + EX_R11) = saved r11
* SPRN_SPRG_##type##_SCRATCH = saved r13
*
- * Expected inputs (CRIT exception type):
- * r10 = saved CR
- * r13 = PACA_POINTER
- * *(r13 + PACA_EX##type + EX_R10) = saved r10
- * *(r13 + PACA_EX##type + EX_R11) = saved r11
- * *(r13 + PACA_EX##type + EX_R13) = saved r13
- *
* Expected inputs (TLB exception type):
* r10 = saved CR
* r13 = PACA_POINTER
diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index 9c5dbc3..948f01a 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h
@@ -146,7 +146,7 @@
u8 io_sync; /* writel() needs spin_unlock sync */
u8 irq_work_pending; /* IRQ_WORK interrupt while soft-disable */
u8 nap_state_lost; /* NV GPR values lost in power7_idle */
- u64 sprg3; /* Saved user-visible sprg */
+ u64 sprg_vdso; /* Saved user-visible sprg */
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
u64 tm_scratch; /* TM scratch area for reclaim */
#endif
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index bf0fb4d..f7251c2 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -577,9 +577,13 @@
#define SPRN_SPRG3 0x113 /* Special Purpose Register General 3 */
#define SPRN_USPRG3 0x103 /* SPRG3 userspace read */
#define SPRN_SPRG4 0x114 /* Special Purpose Register General 4 */
+#define SPRN_USPRG4 0x104 /* SPRG4 userspace read */
#define SPRN_SPRG5 0x115 /* Special Purpose Register General 5 */
+#define SPRN_USPRG5 0x105 /* SPRG5 userspace read */
#define SPRN_SPRG6 0x116 /* Special Purpose Register General 6 */
+#define SPRN_USPRG6 0x106 /* SPRG6 userspace read */
#define SPRN_SPRG7 0x117 /* Special Purpose Register General 7 */
+#define SPRN_USPRG7 0x107 /* SPRG7 userspace read */
#define SPRN_SRR0 0x01A /* Save/Restore Register 0 */
#define SPRN_SRR1 0x01B /* Save/Restore Register 1 */
#define SRR1_ISI_NOPT 0x40000000 /* ISI: Not found in hash */
@@ -879,11 +883,10 @@
* 64-bit embedded
* - SPRG0 generic exception scratch
* - SPRG2 TLB exception stack
- * - SPRG3 critical exception scratch and
- * CPU and NUMA node for VDSO getcpu (user visible)
+ * - SPRG3 critical exception scratch (user visible, sorry!)
* - SPRG4 unused (user visible)
* - SPRG6 TLB miss scratch (user visible, sorry !)
- * - SPRG7 critical exception scratch
+ * - SPRG7 CPU and NUMA node for VDSO getcpu (user visible)
* - SPRG8 machine check exception scratch
* - SPRG9 debug exception scratch
*
@@ -940,6 +943,8 @@
#define SPRN_SPRG_SCRATCH0 SPRN_SPRG2
#define SPRN_SPRG_HPACA SPRN_HSPRG0
#define SPRN_SPRG_HSCRATCH0 SPRN_HSPRG1
+#define SPRN_SPRG_VDSO_READ SPRN_USPRG3
+#define SPRN_SPRG_VDSO_WRITE SPRN_SPRG3
#define GET_PACA(rX) \
BEGIN_FTR_SECTION_NESTED(66); \
@@ -983,6 +988,8 @@
#define SPRN_SPRG_TLB_SCRATCH SPRN_SPRG6
#define SPRN_SPRG_GEN_SCRATCH SPRN_SPRG0
#define SPRN_SPRG_GDBELL_SCRATCH SPRN_SPRG_GEN_SCRATCH
+#define SPRN_SPRG_VDSO_READ SPRN_USPRG7
+#define SPRN_SPRG_VDSO_WRITE SPRN_SPRG7
#define SET_PACA(rX) mtspr SPRN_SPRG_PACA,rX
#define GET_PACA(rX) mfspr rX,SPRN_SPRG_PACA