powerpc: Update kernel VSID range

This patch change the kernel VSID range so that we limit VSID_BITS to 37.
This enables us to support 64TB with 65 bit VA (37+28). Without this patch
we have boot hangs on platforms that only support 65 bit VA.

With this patch we now have proto vsid generated as below:

We first generate a 37-bit "proto-VSID". Proto-VSIDs are generated
from mmu context id and effective segment id of the address.

For user processes max context id is limited to ((1ul << 19) - 5)
for kernel space, we use the top 4 context ids to map address as below
0x7fffc -  [ 0xc000000000000000 - 0xc0003fffffffffff ]
0x7fffd -  [ 0xd000000000000000 - 0xd0003fffffffffff ]
0x7fffe -  [ 0xe000000000000000 - 0xe0003fffffffffff ]
0x7ffff -  [ 0xf000000000000000 - 0xf0003fffffffffff ]

Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Tested-by: Geoff Levand <geoff@infradead.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: <stable@vger.kernel.org> [v3.8]

4 files changed, 42 insertions, 41 deletions

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 6ec6c1997b3a..f410c3e12c1e 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -195,6 +195,11 @@ int htab_bolt_mapping(unsigned long vstart, unsigned long vend,
 		unsigned long vpn  = hpt_vpn(vaddr, vsid, ssize);
 		unsigned long tprot = prot;
 
+		/*
+		 * If we hit a bad address return error.
+		 */
+		if (!vsid)
+			return -1;
 		/* Make kernel text executable */
 		if (overlaps_kernel_text(vaddr, vaddr + step))
 			tprot &= ~HPTE_R_N;
@@ -924,11 +929,6 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
 	DBG_LOW("hash_page(ea=%016lx, access=%lx, trap=%lx\n",
 		ea, access, trap);
 
-	if ((ea & ~REGION_MASK) >= PGTABLE_RANGE) {
-		DBG_LOW(" out of pgtable range !\n");
- 		return 1;
-	}
-
 	/* Get region & vsid */
  	switch (REGION_ID(ea)) {
 	case USER_REGION_ID:
@@ -959,6 +959,11 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
 	}
 	DBG_LOW(" mm=%p, mm->pgdir=%p, vsid=%016lx\n", mm, mm->pgd, vsid);
 
+	/* Bad address. */
+	if (!vsid) {
+		DBG_LOW("Bad address!\n");
+		return 1;
+	}
 	/* Get pgdir */
 	pgdir = mm->pgd;
 	if (pgdir == NULL)
@@ -1128,6 +1133,8 @@ void hash_preload(struct mm_struct *mm, unsigned long ea,
 	/* Get VSID */
 	ssize = user_segment_size(ea);
 	vsid = get_vsid(mm->context.id, ea, ssize);
+	if (!vsid)
+		return;
 
 	/* Hash doesn't like irqs */
 	local_irq_save(flags);
@@ -1235,6 +1242,9 @@ static void kernel_map_linear_page(unsigned long vaddr, unsigned long lmi)
 	hash = hpt_hash(vpn, PAGE_SHIFT, mmu_kernel_ssize);
 	hpteg = ((hash & htab_hash_mask) * HPTES_PER_GROUP);
 
+	/* Don't create HPTE entries for bad address */
+	if (!vsid)
+		return;
 	ret = ppc_md.hpte_insert(hpteg, vpn, __pa(vaddr),
 				 mode, HPTE_V_BOLTED,
 				 mmu_linear_psize, mmu_kernel_ssize);
diff --git a/arch/powerpc/mm/mmu_context_hash64.c b/arch/powerpc/mm/mmu_context_hash64.c
index 40bc5b0ace54..d1d1b92c5b99 100644
--- a/arch/powerpc/mm/mmu_context_hash64.c
+++ b/arch/powerpc/mm/mmu_context_hash64.c
@@ -29,15 +29,6 @@
 static DEFINE_SPINLOCK(mmu_context_lock);
 static DEFINE_IDA(mmu_context_ida);
 
-/*
- * 256MB segment
- * The proto-VSID space has 2^(CONTEX_BITS + USER_ESID_BITS) - 1 segments
- * available for user mappings. Each segment contains 2^28 bytes. Each
- * context maps 2^46 bytes (64TB) so we can support 2^19-1 contexts
- * (19 == 37 + 28 - 46).
- */
-#define MAX_CONTEXT	((1UL << CONTEXT_BITS) - 1)
-
 int __init_new_context(void)
 {
 	int index;
@@ -56,7 +47,7 @@ again:
 	else if (err)
 		return err;
 
-	if (index > MAX_CONTEXT) {
+	if (index > MAX_USER_CONTEXT) {
 		spin_lock(&mmu_context_lock);
 		ida_remove(&mmu_context_ida, index);
 		spin_unlock(&mmu_context_lock);
diff --git a/arch/powerpc/mm/slb_low.S b/arch/powerpc/mm/slb_low.S
index 1a16ca227757..77aafaa1ab09 100644
--- a/arch/powerpc/mm/slb_low.S
+++ b/arch/powerpc/mm/slb_low.S
@@ -31,10 +31,15 @@
  * No other registers are examined or changed.
  */
 _GLOBAL(slb_allocate_realmode)
-	/* r3 = faulting address */
+	/*
+	 * check for bad kernel/user address
+	 * (ea & ~REGION_MASK) >= PGTABLE_RANGE
+	 */
+	rldicr. r9,r3,4,(63 - 46 - 4)
+	bne-	8f
 
 	srdi	r9,r3,60		/* get region */
-	srdi	r10,r3,28		/* get esid */
+	srdi	r10,r3,SID_SHIFT	/* get esid */
 	cmpldi	cr7,r9,0xc		/* cmp PAGE_OFFSET for later use */
 
 	/* r3 = address, r10 = esid, cr7 = <> PAGE_OFFSET */
@@ -56,12 +61,14 @@ _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
+	 * context = (MAX_USER_CONTEXT) + ((ea >> 60) - 0xc) + 1
+	 * r9 = region id.
 	 */
-	rldimi  r10,r9,(CONTEXT_BITS + USER_ESID_BITS),0
+	addis	r9,r9,(MAX_USER_CONTEXT - 0xc + 1)@ha
+	addi	r9,r9,(MAX_USER_CONTEXT - 0xc + 1)@l
+
+
 BEGIN_FTR_SECTION
 	b	slb_finish_load
 END_MMU_FTR_SECTION_IFCLR(MMU_FTR_1T_SEGMENT)
@@ -91,24 +98,19 @@ _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
+	 * context = (MAX_USER_CONTEXT) + ((ea >> 60) - 0xc) + 1
+	 * r9 = region id.
 	 */
-	rldimi  r10,r9,(CONTEXT_BITS + USER_ESID_BITS),0
+	addis	r9,r9,(MAX_USER_CONTEXT - 0xc + 1)@ha
+	addi	r9,r9,(MAX_USER_CONTEXT - 0xc + 1)@l
+
 BEGIN_FTR_SECTION
 	b	slb_finish_load
 END_MMU_FTR_SECTION_IFCLR(MMU_FTR_1T_SEGMENT)
 	b	slb_finish_load_1T
 
-0:	/* user address: proto-VSID = context << 15 | ESID. First check
-	 * if the address is within the boundaries of the user region
-	 */
-	srdi.	r9,r10,USER_ESID_BITS
-	bne-	8f			/* invalid ea bits set */
-
-
+0:
 	/* when using slices, we extract the psize off the slice bitmaps
 	 * and then we need to get the sllp encoding off the mmu_psize_defs
 	 * array.
@@ -164,15 +166,13 @@ END_MMU_FTR_SECTION_IFCLR(MMU_FTR_1T_SEGMENT)
 	ld	r9,PACACONTEXTID(r13)
 BEGIN_FTR_SECTION
 	cmpldi	r10,0x1000
-END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT)
-	rldimi	r10,r9,USER_ESID_BITS,0
-BEGIN_FTR_SECTION
 	bge	slb_finish_load_1T
 END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT)
 	b	slb_finish_load
 
 8:	/* invalid EA */
 	li	r10,0			/* BAD_VSID */
+	li	r9,0			/* BAD_VSID */
 	li	r11,SLB_VSID_USER	/* flags don't much matter */
 	b	slb_finish_load
 
@@ -221,8 +221,6 @@ _GLOBAL(slb_allocate_user)
 
 	/* get context to calculate proto-VSID */
 	ld	r9,PACACONTEXTID(r13)
-	rldimi	r10,r9,USER_ESID_BITS,0
-
 	/* fall through slb_finish_load */
 
 #endif /* __DISABLED__ */
@@ -231,9 +229,10 @@ _GLOBAL(slb_allocate_user)
 /*
  * Finish loading of an SLB entry and return
  *
- * r3 = EA, r10 = proto-VSID, r11 = flags, clobbers r9, cr7 = <> PAGE_OFFSET
+ * r3 = EA, r9 = context, r10 = ESID, r11 = flags, clobbers r9, cr7 = <> PAGE_OFFSET
  */
 slb_finish_load:
+	rldimi  r10,r9,USER_ESID_BITS,0
 	ASM_VSID_SCRAMBLE(r10,r9,256M)
 	/*
 	 * bits above VSID_BITS_256M need to be ignored from r10
@@ -298,10 +297,11 @@ _GLOBAL(slb_compare_rr_to_size)
 /*
  * Finish loading of a 1T SLB entry (for the kernel linear mapping) and return.
  *
- * r3 = EA, r10 = proto-VSID, r11 = flags, clobbers r9
+ * r3 = EA, r9 = context, r10 = ESID(256MB), r11 = flags, clobbers r9
  */
 slb_finish_load_1T:
-	srdi	r10,r10,40-28		/* get 1T ESID */
+	srdi	r10,r10,(SID_SHIFT_1T - SID_SHIFT)	/* get 1T ESID */
+	rldimi  r10,r9,USER_ESID_BITS_1T,0
 	ASM_VSID_SCRAMBLE(r10,r9,1T)
 	/*
 	 * bits above VSID_BITS_1T need to be ignored from r10
diff --git a/arch/powerpc/mm/tlb_hash64.c b/arch/powerpc/mm/tlb_hash64.c
index 0d82ef50dc3f..023ec8a13f38 100644
--- a/arch/powerpc/mm/tlb_hash64.c
+++ b/arch/powerpc/mm/tlb_hash64.c
@@ -82,11 +82,11 @@ void hpte_need_flush(struct mm_struct *mm, unsigned long addr,
 	if (!is_kernel_addr(addr)) {
 		ssize = user_segment_size(addr);
 		vsid = get_vsid(mm->context.id, addr, ssize);
-		WARN_ON(vsid == 0);
 	} else {
 		vsid = get_kernel_vsid(addr, mmu_kernel_ssize);
 		ssize = mmu_kernel_ssize;
 	}
+	WARN_ON(vsid == 0);
 	vpn = hpt_vpn(addr, vsid, ssize);
 	rpte = __real_pte(__pte(pte), ptep);