[PATCH -V4 12/12] arch/powerpc: properly isolate kernel and user proto-VSID

[Aneesh Kumar K.V]

From: "Aneesh Kumar K.V" <aneesh.kumar at linux.vnet.ibm.com>

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
patchset we need to have kernel proto-VSID in the
[2^37 to 2^38 - 1] range due to the increased USER_ESID_BITS.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/mmu-hash64.h |   16 +++++++++++++---
 arch/powerpc/kernel/exceptions-64s.S  |    4 +++-
 arch/powerpc/mm/mmu_context_hash64.c  |    2 +-
 arch/powerpc/mm/slb_low.S             |    8 ++++++++
 4 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/mmu-hash64.h b/arch/powerpc/include/asm/mmu-hash64.h
index daa3e4b..8e97715 100644
--- a/arch/powerpc/include/asm/mmu-hash64.h
+++ b/arch/powerpc/include/asm/mmu-hash64.h
@@ -516,9 +516,19 @@ typedef struct {
 /* This is only valid for addresses >= PAGE_OFFSET */
 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/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 1c06d29..40ed208 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -958,7 +958,9 @@ _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/mmu_context_hash64.c b/arch/powerpc/mm/mmu_context_hash64.c
index 40677aa..daa076c 100644
--- a/arch/powerpc/mm/mmu_context_hash64.c
+++ b/arch/powerpc/mm/mmu_context_hash64.c
@@ -34,7 +34,7 @@ static DEFINE_IDA(mmu_context_ida);
  * Each segment contains 2^28 bytes.  Each context maps 2^44 bytes,
  * so we can support 2^19-1 contexts (19 == 35 + 28 - 44).
  */
-#define MAX_CONTEXT	((1UL << 19) - 1)
+#define MAX_CONTEXT	((1UL << CONTEXT_BITS) - 1)
 
 int __init_new_context(void)
 {
diff --git a/arch/powerpc/mm/slb_low.S b/arch/powerpc/mm/slb_low.S
index 7bd8438..2777ba9 100644
--- a/arch/powerpc/mm/slb_low.S
+++ b/arch/powerpc/mm/slb_low.S
@@ -57,9 +57,13 @@ _GLOBAL(slb_allocate_realmode)
 _GLOBAL(slb_miss_kernel_load_linear)
 	li	r11,0
 BEGIN_FTR_SECTION
+	li	r9,0x1
+	rldimi  r10,r9,(CONTEXT_BITS + USER_ESID_BITS),0
 	b	slb_finish_load
 END_MMU_FTR_SECTION_IFCLR(MMU_FTR_1T_SEGMENT)
 	srdi	r10,r10,40-28		/* get 1T ESID */
+	li	r9,0x1
+	rldimi  r10,r9,(CONTEXT_BITS + USER_ESID_BITS_1T),0
 	b	slb_finish_load_1T
 
 1:
@@ -87,9 +91,13 @@ _GLOBAL(slb_miss_kernel_load_vmemmap)
 	li	r11,0
 6:
 BEGIN_FTR_SECTION
+	li	r9,0x1
+	rldimi  r10,r9,(CONTEXT_BITS + USER_ESID_BITS),0
 	b	slb_finish_load
 END_MMU_FTR_SECTION_IFCLR(MMU_FTR_1T_SEGMENT)
 	srdi	r10,r10,40-28		/* get 1T ESID */
+	li	r9,0x1
+	rldimi  r10,r9,(CONTEXT_BITS + USER_ESID_BITS_1T),0
 	b	slb_finish_load_1T
 
 0:	/* user address: proto-VSID = context << 15 | ESID. First check
-- 
1.7.10