powerpc/8xx: Implement support of hugepages

8xx uses a two level page table with two different linux page size
support (4k and 16k). 8xx also support two different hugepage sizes
512k and 8M. In order to support them on linux we define two different
page table layout.

The size of pages is in the PGD entry, using PS field (bits 28-29):
00 : Small pages (4k or 16k)
01 : 512k pages
10 : reserved
11 : 8M pages

For 512K hugepage size a pgd entry have the below format
[<hugepte address >0101] . The hugepte table allocated will contain 8
entries pointing to 512K huge pte in 4k pages mode and 64 entries in
16k pages mode.

For 8M in 16k mode, a pgd entry have the below format
[<hugepte address >1101] . The hugepte table allocated will contain 8
entries pointing to 8M huge pte.

For 8M in 4k mode, multiple pgd entries point to the same hugepte
address and pgd entry will have the below format
[<hugepte address>1101]. The hugepte table allocated will only have one
entry.

For the time being, we do not support CPU15 ERRATA when HUGETLB is
selected

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> (v3, for the generic bits)
Signed-off-by: Scott Wood <oss@buserror.net>

1 files changed, 113 insertions, 6 deletions

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index fb133a163263..1a9c99d3e5d8 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -73,6 +73,9 @@
 #define RPN_PATTERN	0x00f0
 #endif
 
+#define PAGE_SHIFT_512K		19
+#define PAGE_SHIFT_8M		23
+
 	__HEAD
 _ENTRY(_stext);
 _ENTRY(_start);
@@ -322,7 +325,7 @@ SystemCall:
 #endif
 
 InstructionTLBMiss:
-#if defined(CONFIG_8xx_CPU6) || defined(CONFIG_MODULES) || defined (CONFIG_DEBUG_PAGEALLOC)
+#if defined(CONFIG_8xx_CPU6) || defined(CONFIG_MODULES) || defined (CONFIG_DEBUG_PAGEALLOC) || defined (CONFIG_HUGETLB_PAGE)
 	mtspr	SPRN_SPRG_SCRATCH2, r3
 #endif
 	EXCEPTION_PROLOG_0
@@ -332,10 +335,12 @@ InstructionTLBMiss:
 	 */
 	mfspr	r10, SPRN_SRR0	/* Get effective address of fault */
 	INVALIDATE_ADJACENT_PAGES_CPU15(r11, r10)
-#if defined(CONFIG_MODULES) || defined (CONFIG_DEBUG_PAGEALLOC)
 	/* Only modules will cause ITLB Misses as we always
 	 * pin the first 8MB of kernel memory */
+#if defined(CONFIG_MODULES) || defined (CONFIG_DEBUG_PAGEALLOC) || defined (CONFIG_HUGETLB_PAGE)
 	mfcr	r3
+#endif
+#if defined(CONFIG_MODULES) || defined (CONFIG_DEBUG_PAGEALLOC)
 	IS_KERNEL(r11, r10)
 #endif
 	mfspr	r11, SPRN_M_TW	/* Get level 1 table */
@@ -343,7 +348,6 @@ InstructionTLBMiss:
 	BRANCH_UNLESS_KERNEL(3f)
 	lis	r11, (swapper_pg_dir-PAGE_OFFSET)@ha
 3:
-	mtcr	r3
 #endif
 	/* Insert level 1 index */
 	rlwimi	r11, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
@@ -351,14 +355,25 @@ InstructionTLBMiss:
 
 	/* Extract level 2 index */
 	rlwinm	r10, r10, 32 - (PAGE_SHIFT - 2), 32 - PAGE_SHIFT, 29
+#ifdef CONFIG_HUGETLB_PAGE
+	mtcr	r11
+	bt-	28, 10f		/* bit 28 = Large page (8M) */
+	bt-	29, 20f		/* bit 29 = Large page (8M or 512k) */
+#endif
 	rlwimi	r10, r11, 0, 0, 32 - PAGE_SHIFT - 1	/* Add level 2 base */
 	lwz	r10, 0(r10)	/* Get the pte */
-
+4:
+#if defined(CONFIG_MODULES) || defined (CONFIG_DEBUG_PAGEALLOC) || defined (CONFIG_HUGETLB_PAGE)
+	mtcr	r3
+#endif
 	/* Insert the APG into the TWC from the Linux PTE. */
 	rlwimi	r11, r10, 0, 25, 26
 	/* Load the MI_TWC with the attributes for this "segment." */
 	MTSPR_CPU6(SPRN_MI_TWC, r11, r3)	/* Set segment attributes */
 
+#if defined (CONFIG_HUGETLB_PAGE) && defined (CONFIG_PPC_4K_PAGES)
+	rlwimi	r10, r11, 1, MI_SPS16K
+#endif
 #ifdef CONFIG_SWAP
 	rlwinm	r11, r10, 32-5, _PAGE_PRESENT
 	and	r11, r11, r10
@@ -371,16 +386,45 @@ InstructionTLBMiss:
 	 * set.  All other Linux PTE bits control the behavior
 	 * of the MMU.
 	 */
+#if defined (CONFIG_HUGETLB_PAGE) && defined (CONFIG_PPC_4K_PAGES)
+	rlwimi	r10, r11, 0, 0x0ff0	/* Set 24-27, clear 20-23 */
+#else
 	rlwimi	r10, r11, 0, 0x0ff8	/* Set 24-27, clear 20-23,28 */
+#endif
 	MTSPR_CPU6(SPRN_MI_RPN, r10, r3)	/* Update TLB entry */
 
 	/* Restore registers */
-#if defined(CONFIG_8xx_CPU6) || defined(CONFIG_MODULES) || defined (CONFIG_DEBUG_PAGEALLOC)
+#if defined(CONFIG_8xx_CPU6) || defined(CONFIG_MODULES) || defined (CONFIG_DEBUG_PAGEALLOC) || defined (CONFIG_HUGETLB_PAGE)
 	mfspr	r3, SPRN_SPRG_SCRATCH2
 #endif
 	EXCEPTION_EPILOG_0
 	rfi
 
+#ifdef CONFIG_HUGETLB_PAGE
+10:	/* 8M pages */
+#ifdef CONFIG_PPC_16K_PAGES
+	/* Extract level 2 index */
+	rlwinm	r10, r10, 32 - (PAGE_SHIFT_8M - PAGE_SHIFT), 32 + PAGE_SHIFT_8M - (PAGE_SHIFT << 1), 29
+	/* Add level 2 base */
+	rlwimi	r10, r11, 0, 0, 32 + PAGE_SHIFT_8M - (PAGE_SHIFT << 1) - 1
+#else
+	/* Level 2 base */
+	rlwinm	r10, r11, 0, ~HUGEPD_SHIFT_MASK
+#endif
+	lwz	r10, 0(r10)	/* Get the pte */
+	rlwinm	r11, r11, 0, 0xf
+	b	4b
+
+20:	/* 512k pages */
+	/* Extract level 2 index */
+	rlwinm	r10, r10, 32 - (PAGE_SHIFT_512K - PAGE_SHIFT), 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1), 29
+	/* Add level 2 base */
+	rlwimi	r10, r11, 0, 0, 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1) - 1
+	lwz	r10, 0(r10)	/* Get the pte */
+	rlwinm	r11, r11, 0, 0xf
+	b	4b
+#endif
+
 	. = 0x1200
 DataStoreTLBMiss:
 	mtspr	SPRN_SPRG_SCRATCH2, r3
@@ -407,7 +451,6 @@ _ENTRY(DTLBMiss_jmp)
 #endif
 	blt	cr7, DTLBMissLinear
 3:
-	mtcr	r3
 	mfspr	r10, SPRN_MD_EPN
 
 	/* Insert level 1 index */
@@ -418,8 +461,15 @@ _ENTRY(DTLBMiss_jmp)
 	 */
 	/* Extract level 2 index */
 	rlwinm	r10, r10, 32 - (PAGE_SHIFT - 2), 32 - PAGE_SHIFT, 29
+#ifdef CONFIG_HUGETLB_PAGE
+	mtcr	r11
+	bt-	28, 10f		/* bit 28 = Large page (8M) */
+	bt-	29, 20f		/* bit 29 = Large page (8M or 512k) */
+#endif
 	rlwimi	r10, r11, 0, 0, 32 - PAGE_SHIFT - 1	/* Add level 2 base */
 	lwz	r10, 0(r10)	/* Get the pte */
+4:
+	mtcr	r3
 
 	/* Insert the Guarded flag and APG into the TWC from the Linux PTE.
 	 * It is bit 26-27 of both the Linux PTE and the TWC (at least
@@ -434,6 +484,11 @@ _ENTRY(DTLBMiss_jmp)
 	rlwimi	r11, r10, 32-5, 30, 30
 	MTSPR_CPU6(SPRN_MD_TWC, r11, r3)
 
+	/* In 4k pages mode, SPS (bit 28) in RPN must match PS[1] (bit 29)
+	 * In 16k pages mode, SPS is always 1 */
+#if defined (CONFIG_HUGETLB_PAGE) && defined (CONFIG_PPC_4K_PAGES)
+	rlwimi	r10, r11, 1, MD_SPS16K
+#endif
 	/* Both _PAGE_ACCESSED and _PAGE_PRESENT has to be set.
 	 * We also need to know if the insn is a load/store, so:
 	 * Clear _PAGE_PRESENT and load that which will
@@ -455,7 +510,11 @@ _ENTRY(DTLBMiss_jmp)
 	 * of the MMU.
 	 */
 	li	r11, RPN_PATTERN
+#if defined (CONFIG_HUGETLB_PAGE) && defined (CONFIG_PPC_4K_PAGES)
+	rlwimi	r10, r11, 0, 24, 27	/* Set 24-27 */
+#else
 	rlwimi	r10, r11, 0, 24, 28	/* Set 24-27, clear 28 */
+#endif
 	rlwimi	r10, r11, 0, 20, 20	/* clear 20 */
 	MTSPR_CPU6(SPRN_MD_RPN, r10, r3)	/* Update TLB entry */
 
@@ -465,6 +524,30 @@ _ENTRY(DTLBMiss_jmp)
 	EXCEPTION_EPILOG_0
 	rfi
 
+#ifdef CONFIG_HUGETLB_PAGE
+10:	/* 8M pages */
+	/* Extract level 2 index */
+#ifdef CONFIG_PPC_16K_PAGES
+	rlwinm	r10, r10, 32 - (PAGE_SHIFT_8M - PAGE_SHIFT), 32 + PAGE_SHIFT_8M - (PAGE_SHIFT << 1), 29
+	/* Add level 2 base */
+	rlwimi	r10, r11, 0, 0, 32 + PAGE_SHIFT_8M - (PAGE_SHIFT << 1) - 1
+#else
+	/* Level 2 base */
+	rlwinm	r10, r11, 0, ~HUGEPD_SHIFT_MASK
+#endif
+	lwz	r10, 0(r10)	/* Get the pte */
+	rlwinm	r11, r11, 0, 0xf
+	b	4b
+
+20:	/* 512k pages */
+	/* Extract level 2 index */
+	rlwinm	r10, r10, 32 - (PAGE_SHIFT_512K - PAGE_SHIFT), 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1), 29
+	/* Add level 2 base */
+	rlwimi	r10, r11, 0, 0, 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1) - 1
+	lwz	r10, 0(r10)	/* Get the pte */
+	rlwinm	r11, r11, 0, 0xf
+	b	4b
+#endif
 
 /* This is an instruction TLB error on the MPC8xx.  This could be due
  * to many reasons, such as executing guarded memory or illegal instruction
@@ -586,6 +669,9 @@ _ENTRY(FixupDAR_cmp)
 	/* Insert level 1 index */
 3:	rlwimi	r11, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
 	lwz	r11, (swapper_pg_dir-PAGE_OFFSET)@l(r11)	/* Get the level 1 entry */
+	mtcr	r11
+	bt	28,200f		/* bit 28 = Large page (8M) */
+	bt	29,202f		/* bit 29 = Large page (8M or 512K) */
 	rlwinm	r11, r11,0,0,19	/* Extract page descriptor page address */
 	/* Insert level 2 index */
 	rlwimi	r11, r10, 32 - (PAGE_SHIFT - 2), 32 - PAGE_SHIFT, 29
@@ -611,6 +697,27 @@ _ENTRY(FixupDAR_cmp)
 141:	mfspr	r10,SPRN_SPRG_SCRATCH2
 	b	DARFixed	/* Nope, go back to normal TLB processing */
 
+	/* concat physical page address(r11) and page offset(r10) */
+200:
+#ifdef CONFIG_PPC_16K_PAGES
+	rlwinm	r11, r11, 0, 0, 32 + PAGE_SHIFT_8M - (PAGE_SHIFT << 1) - 1
+	rlwimi	r11, r10, 32 - (PAGE_SHIFT_8M - 2), 32 + PAGE_SHIFT_8M - (PAGE_SHIFT << 1), 29
+#else
+	rlwinm	r11, r10, 0, ~HUGEPD_SHIFT_MASK
+#endif
+	lwz	r11, 0(r11)	/* Get the pte */
+	/* concat physical page address(r11) and page offset(r10) */
+	rlwimi	r11, r10, 0, 32 - PAGE_SHIFT_8M, 31
+	b	201b
+
+202:
+	rlwinm	r11, r11, 0, 0, 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1) - 1
+	rlwimi	r11, r10, 32 - (PAGE_SHIFT_512K - 2), 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1), 29
+	lwz	r11, 0(r11)	/* Get the pte */
+	/* concat physical page address(r11) and page offset(r10) */
+	rlwimi	r11, r10, 0, 32 - PAGE_SHIFT_512K, 31
+	b	201b
+
 144:	mfspr	r10, SPRN_DSISR
 	rlwinm	r10, r10,0,7,5	/* Clear store bit for buggy dcbst insn */
 	mtspr	SPRN_DSISR, r10