[PATCH 05/10] powerpc/booke64: Use SPRG7 for VDSO
Scott Wood
scottwood at freescale.com
Fri Mar 14 11:00:44 EST 2014
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 at freescale.com>
Cc: Mihai Caraman <mihai.caraman at freescale.com>
Cc: Anton Blanchard <anton at samba.org>
Cc: Paul Mackerras <paulus at samba.org>
Cc: kvm-ppc at vger.kernel.org
---
arch/powerpc/include/asm/exception-64e.h | 5 ++---
arch/powerpc/include/asm/kvm_booke_hv_asm.h | 9 +--------
arch/powerpc/include/asm/paca.h | 2 +-
arch/powerpc/include/asm/reg.h | 13 ++++++++++---
arch/powerpc/kernel/asm-offsets.c | 2 +-
arch/powerpc/kernel/exceptions-64e.S | 19 ++-----------------
arch/powerpc/kernel/vdso.c | 8 ++++----
arch/powerpc/kernel/vdso32/getcpu.S | 2 +-
arch/powerpc/kernel/vdso64/getcpu.S | 2 +-
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 4 ++--
arch/powerpc/kvm/book3s_interrupts.S | 4 ++--
arch/powerpc/kvm/bookehv_interrupts.S | 10 ++++++----
12 files changed, 33 insertions(+), 47 deletions(-)
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 @@ struct paca_struct {
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 90c06ec..b9ac329 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
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index b5aacf7..dba8140 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -253,7 +253,7 @@ int main(void)
DEFINE(PACA_SYSTEM_TIME, offsetof(struct paca_struct, system_time));
DEFINE(PACA_TRAP_SAVE, offsetof(struct paca_struct, trap_save));
DEFINE(PACA_NAPSTATELOST, offsetof(struct paca_struct, nap_state_lost));
- DEFINE(PACA_SPRG3, offsetof(struct paca_struct, sprg3));
+ DEFINE(PACA_SPRG_VDSO, offsetof(struct paca_struct, sprg_vdso));
#endif /* CONFIG_PPC64 */
/* RTAS */
diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index 41380a4..89e1133 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)
diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index 094e45c..ce74c33 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -715,8 +715,8 @@ int vdso_getcpu_init(void)
unsigned long cpu, node, val;
/*
- * SPRG3 contains the CPU in the bottom 16 bits and the NUMA node in
- * the next 16 bits. The VDSO uses this to implement getcpu().
+ * SPRG_VDSO contains the CPU in the bottom 16 bits and the NUMA node
+ * in the next 16 bits. The VDSO uses this to implement getcpu().
*/
cpu = get_cpu();
WARN_ON_ONCE(cpu > 0xffff);
@@ -725,8 +725,8 @@ int vdso_getcpu_init(void)
WARN_ON_ONCE(node > 0xffff);
val = (cpu & 0xfff) | ((node & 0xffff) << 16);
- mtspr(SPRN_SPRG3, val);
- get_paca()->sprg3 = val;
+ mtspr(SPRN_SPRG_VDSO_WRITE, val);
+ get_paca()->sprg_vdso = val;
put_cpu();
diff --git a/arch/powerpc/kernel/vdso32/getcpu.S b/arch/powerpc/kernel/vdso32/getcpu.S
index 47afd08..23eb9a9 100644
--- a/arch/powerpc/kernel/vdso32/getcpu.S
+++ b/arch/powerpc/kernel/vdso32/getcpu.S
@@ -29,7 +29,7 @@
*/
V_FUNCTION_BEGIN(__kernel_getcpu)
.cfi_startproc
- mfspr r5,SPRN_USPRG3
+ mfspr r5,SPRN_SPRG_VDSO_READ
cmpdi cr0,r3,0
cmpdi cr1,r4,0
clrlwi r6,r5,16
diff --git a/arch/powerpc/kernel/vdso64/getcpu.S b/arch/powerpc/kernel/vdso64/getcpu.S
index 47afd08..23eb9a9 100644
--- a/arch/powerpc/kernel/vdso64/getcpu.S
+++ b/arch/powerpc/kernel/vdso64/getcpu.S
@@ -29,7 +29,7 @@
*/
V_FUNCTION_BEGIN(__kernel_getcpu)
.cfi_startproc
- mfspr r5,SPRN_USPRG3
+ mfspr r5,SPRN_SPRG_VDSO_READ
cmpdi cr0,r3,0
cmpdi cr1,r4,0
clrlwi r6,r5,16
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index e66d4ec..fbfca57 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -75,8 +75,8 @@ BEGIN_FTR_SECTION
END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S)
/* Restore SPRG3 */
- ld r3,PACA_SPRG3(r13)
- mtspr SPRN_SPRG3,r3
+ ld r3,PACA_SPRG_VDSO(r13)
+ mtspr SPRN_SPRG_VDSO_WRITE,r3
/* Reload the host's PMU registers */
ld r3, PACALPPACAPTR(r13) /* is the host using the PMU? */
diff --git a/arch/powerpc/kvm/book3s_interrupts.S b/arch/powerpc/kvm/book3s_interrupts.S
index f779450..3533c99 100644
--- a/arch/powerpc/kvm/book3s_interrupts.S
+++ b/arch/powerpc/kvm/book3s_interrupts.S
@@ -153,8 +153,8 @@ kvm_start_lightweight:
* Reload kernel SPRG3 value.
* No need to save guest value as usermode can't modify SPRG3.
*/
- ld r3, PACA_SPRG3(r13)
- mtspr SPRN_SPRG3, r3
+ ld r3, PACA_SPRG_VDSO(r13)
+ mtspr SPRN_SPRG_VDSO_WRITE, r3
#endif /* CONFIG_PPC_BOOK3S_64 */
/* R7 = vcpu */
diff --git a/arch/powerpc/kvm/bookehv_interrupts.S b/arch/powerpc/kvm/bookehv_interrupts.S
index e4185f6..99635a3 100644
--- a/arch/powerpc/kvm/bookehv_interrupts.S
+++ b/arch/powerpc/kvm/bookehv_interrupts.S
@@ -229,11 +229,7 @@
stw r10, VCPU_CR(r4)
PPC_STL r11, VCPU_GPR(R4)(r4)
PPC_STL r5, VCPU_GPR(R5)(r4)
- .if \type == EX_CRIT
- PPC_LL r5, (\paca_ex + EX_R13)(r13)
- .else
mfspr r5, \scratch
- .endif
PPC_STL r6, VCPU_GPR(R6)(r4)
PPC_STL r8, VCPU_GPR(R8)(r4)
PPC_STL r9, VCPU_GPR(R9)(r4)
@@ -435,10 +431,16 @@ _GLOBAL(kvmppc_resume_host)
PPC_STL r5, VCPU_LR(r4)
mfspr r7, SPRN_SPRG5
stw r3, VCPU_VRSAVE(r4)
+#ifdef CONFIG_64BIT
+ PPC_LL r3, PACA_SPRG_VDSO(r13)
+#endif
PPC_STD(r6, VCPU_SHARED_SPRG4, r11)
mfspr r8, SPRN_SPRG6
PPC_STD(r7, VCPU_SHARED_SPRG5, r11)
mfspr r9, SPRN_SPRG7
+#ifdef CONFIG_64BIT
+ mtspr SPRN_SPRG_VDSO_WRITE, r3
+#endif
PPC_STD(r8, VCPU_SHARED_SPRG6, r11)
mfxer r3
PPC_STD(r9, VCPU_SHARED_SPRG7, r11)
--
1.8.3.2
More information about the Linuxppc-dev
mailing list