Patchwork [-V9,09/11] arch/powerpc: Add 64TB support

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Submitter Aneesh Kumar K.V
Date Sept. 10, 2012, 12:52 p.m.
Message ID <1347281577-5460-10-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
Download mbox | patch
Permalink /patch/182880/
State Accepted, archived
Headers show

Comments

Aneesh Kumar K.V - Sept. 10, 2012, 12:52 p.m.
From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>

Increase max addressable range to 64TB. This is not tested on
real hardware yet.

Reviewed-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/mmu-hash64.h        |   42 ++++++++++++++++++++------
 arch/powerpc/include/asm/pgtable-ppc64-4k.h  |    2 +-
 arch/powerpc/include/asm/pgtable-ppc64-64k.h |    2 +-
 arch/powerpc/include/asm/processor.h         |    4 +--
 arch/powerpc/include/asm/sparsemem.h         |    4 +--
 arch/powerpc/kernel/exceptions-64s.S         |    4 ++-
 arch/powerpc/mm/slb_low.S                    |   12 ++++++++
 7 files changed, 54 insertions(+), 16 deletions(-)
Scott Wood - Sept. 12, 2012, 12:58 a.m.
On 09/10/2012 07:52 AM, Aneesh Kumar K.V wrote:
> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
> 
> Increase max addressable range to 64TB. This is not tested on
> real hardware yet.
> 
> Reviewed-by: Paul Mackerras <paulus@samba.org>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> ---
>  arch/powerpc/include/asm/mmu-hash64.h        |   42 ++++++++++++++++++++------
>  arch/powerpc/include/asm/pgtable-ppc64-4k.h  |    2 +-
>  arch/powerpc/include/asm/pgtable-ppc64-64k.h |    2 +-
>  arch/powerpc/include/asm/processor.h         |    4 +--
>  arch/powerpc/include/asm/sparsemem.h         |    4 +--
>  arch/powerpc/kernel/exceptions-64s.S         |    4 ++-
>  arch/powerpc/mm/slb_low.S                    |   12 ++++++++
>  7 files changed, 54 insertions(+), 16 deletions(-)

Bisect shows this patch to be the one that causes hangs on p5020.  It
gets stuck in a loop of TLB misses, bailing on a PUD entry of zero.  The
page fault path runs and returns, but doesn't fix the situation, so it
repeats.  AFAICT the miss handler is behaving correctly.  I'll try to
see what's going on in the page fault code.

-Scott

Patch

diff --git a/arch/powerpc/include/asm/mmu-hash64.h b/arch/powerpc/include/asm/mmu-hash64.h
index 7cbd541..23730ee 100644
--- a/arch/powerpc/include/asm/mmu-hash64.h
+++ b/arch/powerpc/include/asm/mmu-hash64.h
@@ -370,17 +370,21 @@  extern void slb_set_size(u16 size);
  * (head.S) and ASM_VSID_SCRAMBLE (below) are changed accordingly.
  */
 
-#define VSID_MULTIPLIER_256M	ASM_CONST(200730139)	/* 28-bit prime */
-#define VSID_BITS_256M		36
+/*
+ * This should be computed such that protovosid * vsid_mulitplier
+ * doesn't overflow 64 bits. It should also be co-prime to vsid_modulus
+ */
+#define VSID_MULTIPLIER_256M	ASM_CONST(12538073)	/* 24-bit prime */
+#define VSID_BITS_256M		38
 #define VSID_MODULUS_256M	((1UL<<VSID_BITS_256M)-1)
 
 #define VSID_MULTIPLIER_1T	ASM_CONST(12538073)	/* 24-bit prime */
-#define VSID_BITS_1T		24
+#define VSID_BITS_1T		26
 #define VSID_MODULUS_1T		((1UL<<VSID_BITS_1T)-1)
 
 #define CONTEXT_BITS		19
-#define USER_ESID_BITS		16
-#define USER_ESID_BITS_1T	4
+#define USER_ESID_BITS		18
+#define USER_ESID_BITS_1T	6
 
 #define USER_VSID_RANGE	(1UL << (USER_ESID_BITS + SID_SHIFT))
 
@@ -500,12 +504,32 @@  typedef struct {
 	})
 #endif /* 1 */
 
-/* This is only valid for addresses >= PAGE_OFFSET */
+/*
+ * This is only valid for addresses >= PAGE_OFFSET
+ * The proto-VSID space is divided into two class
+ * User:   0 to 2^(CONTEXT_BITS + USER_ESID_BITS) -1
+ * kernel: 2^(CONTEXT_BITS + USER_ESID_BITS) to 2^(VSID_BITS) - 1
+ *
+ * With KERNEL_START at 0xc000000000000000, the proto vsid for
+ * the kernel ends up with 0xc00000000 (36 bits). With 64TB
+ * support we need to have kernel proto-VSID in the
+ * [2^37 to 2^38 - 1] range due to the increased USER_ESID_BITS.
+ */
 static inline unsigned long get_kernel_vsid(unsigned long ea, int ssize)
 {
-	if (ssize == MMU_SEGSIZE_256M)
-		return vsid_scramble(ea >> SID_SHIFT, 256M);
-	return vsid_scramble(ea >> SID_SHIFT_1T, 1T);
+	unsigned long proto_vsid;
+	/*
+	 * We need to make sure proto_vsid for the kernel is
+	 * >= 2^(CONTEXT_BITS + USER_ESID_BITS[_1T])
+	 */
+	if (ssize == MMU_SEGSIZE_256M) {
+		proto_vsid = ea >> SID_SHIFT;
+		proto_vsid |= (1UL << (CONTEXT_BITS + USER_ESID_BITS));
+		return vsid_scramble(proto_vsid, 256M);
+	}
+	proto_vsid = ea >> SID_SHIFT_1T;
+	proto_vsid |= (1UL << (CONTEXT_BITS + USER_ESID_BITS_1T));
+	return vsid_scramble(proto_vsid, 1T);
 }
 
 /* Returns the segment size indicator for a user address */
diff --git a/arch/powerpc/include/asm/pgtable-ppc64-4k.h b/arch/powerpc/include/asm/pgtable-ppc64-4k.h
index 6eefdcf..b3eccf2 100644
--- a/arch/powerpc/include/asm/pgtable-ppc64-4k.h
+++ b/arch/powerpc/include/asm/pgtable-ppc64-4k.h
@@ -7,7 +7,7 @@ 
  */
 #define PTE_INDEX_SIZE  9
 #define PMD_INDEX_SIZE  7
-#define PUD_INDEX_SIZE  7
+#define PUD_INDEX_SIZE  9
 #define PGD_INDEX_SIZE  9
 
 #ifndef __ASSEMBLY__
diff --git a/arch/powerpc/include/asm/pgtable-ppc64-64k.h b/arch/powerpc/include/asm/pgtable-ppc64-64k.h
index 90533dd..be4e287 100644
--- a/arch/powerpc/include/asm/pgtable-ppc64-64k.h
+++ b/arch/powerpc/include/asm/pgtable-ppc64-64k.h
@@ -7,7 +7,7 @@ 
 #define PTE_INDEX_SIZE  12
 #define PMD_INDEX_SIZE  12
 #define PUD_INDEX_SIZE	0
-#define PGD_INDEX_SIZE  4
+#define PGD_INDEX_SIZE  6
 
 #ifndef __ASSEMBLY__
 #define PTE_TABLE_SIZE	(sizeof(real_pte_t) << PTE_INDEX_SIZE)
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 53b6dfa..00bda2f 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -97,8 +97,8 @@  extern struct task_struct *last_task_used_spe;
 #endif
 
 #ifdef CONFIG_PPC64
-/* 64-bit user address space is 44-bits (16TB user VM) */
-#define TASK_SIZE_USER64 (0x0000100000000000UL)
+/* 64-bit user address space is 46-bits (64TB user VM) */
+#define TASK_SIZE_USER64 (0x0000400000000000UL)
 
 /* 
  * 32-bit user address space is 4GB - 1 page 
diff --git a/arch/powerpc/include/asm/sparsemem.h b/arch/powerpc/include/asm/sparsemem.h
index 0c5fa31..f6fc0ee 100644
--- a/arch/powerpc/include/asm/sparsemem.h
+++ b/arch/powerpc/include/asm/sparsemem.h
@@ -10,8 +10,8 @@ 
  */
 #define SECTION_SIZE_BITS       24
 
-#define MAX_PHYSADDR_BITS       44
-#define MAX_PHYSMEM_BITS        44
+#define MAX_PHYSADDR_BITS       46
+#define MAX_PHYSMEM_BITS        46
 
 #endif /* CONFIG_SPARSEMEM */
 
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index e894515..d980818 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -959,7 +959,9 @@  _GLOBAL(do_stab_bolted)
 	rldimi	r10,r11,7,52	/* r10 = first ste of the group */
 
 	/* Calculate VSID */
-	/* This is a kernel address, so protovsid = ESID */
+	/* This is a kernel address, so protovsid = ESID | 1 << 37 */
+	li	r9,0x1
+	rldimi  r11,r9,(CONTEXT_BITS + USER_ESID_BITS),0
 	ASM_VSID_SCRAMBLE(r11, r9, 256M)
 	rldic	r9,r11,12,16	/* r9 = vsid << 12 */
 
diff --git a/arch/powerpc/mm/slb_low.S b/arch/powerpc/mm/slb_low.S
index f6a2625..1a16ca2 100644
--- a/arch/powerpc/mm/slb_low.S
+++ b/arch/powerpc/mm/slb_low.S
@@ -56,6 +56,12 @@  _GLOBAL(slb_allocate_realmode)
 	 */
 _GLOBAL(slb_miss_kernel_load_linear)
 	li	r11,0
+	li	r9,0x1
+	/*
+	 * for 1T we shift 12 bits more.  slb_finish_load_1T will do
+	 * the necessary adjustment
+	 */
+	rldimi  r10,r9,(CONTEXT_BITS + USER_ESID_BITS),0
 BEGIN_FTR_SECTION
 	b	slb_finish_load
 END_MMU_FTR_SECTION_IFCLR(MMU_FTR_1T_SEGMENT)
@@ -85,6 +91,12 @@  _GLOBAL(slb_miss_kernel_load_vmemmap)
 	_GLOBAL(slb_miss_kernel_load_io)
 	li	r11,0
 6:
+	li	r9,0x1
+	/*
+	 * for 1T we shift 12 bits more.  slb_finish_load_1T will do
+	 * the necessary adjustment
+	 */
+	rldimi  r10,r9,(CONTEXT_BITS + USER_ESID_BITS),0
 BEGIN_FTR_SECTION
 	b	slb_finish_load
 END_MMU_FTR_SECTION_IFCLR(MMU_FTR_1T_SEGMENT)