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]

1 files changed, 25 insertions, 25 deletions

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