powerpc/64e: remove unused IBM HTW code

Patch series "Reimplement huge pages without hugepd on powerpc (8xx, e500,
book3s/64)", v7.

Unlike most architectures, powerpc 8xx HW requires a two-level pagetable
topology for all page sizes.  So a leaf PMD-contig approach is not
feasible as such.

Possible sizes on 8xx are 4k, 16k, 512k and 8M.

First level (PGD/PMD) covers 4M per entry.  For 8M pages, two PMD entries
must point to a single entry level-2 page table.  Until now that was done
using hugepd.  This series changes it to use standard page tables where
the entry is replicated 1024 times on each of the two pagetables refered
by the two associated PMD entries for that 8M page.

For e500 and book3s/64 there are less constraints because it is not tied
to the HW assisted tablewalk like on 8xx, so it is easier to use leaf PMDs
(and PUDs).

On e500 the supported page sizes are 4M, 16M, 64M, 256M and 1G.  All at
PMD level on e500/32 (mpc85xx) and mix of PMD and PUD for e500/64.  We
encode page size with 4 available bits in PTE entries.  On e300/32 PGD
entries size is increases to 64 bits in order to allow leaf-PMD entries
because PTE are 64 bits on e500.

On book3s/64 only the hash-4k mode is concerned.  It supports 16M pages as
cont-PMD and 16G pages as cont-PUD.  In other modes (radix-4k, radix-6k
and hash-64k) the sizes match with PMD and PUD sizes so that's just leaf
entries.  The hash processing make things a bit more complex.  To ease
things, __hash_page_huge() is modified to bail out when DIRTY or ACCESSED
bits are missing, leaving it to mm core to fix it.


This patch (of 23):

The nohash HTW_IBM (Hardware Table Walk) code is unused since support for
A2 was removed in commit fb5a515704d7 ("powerpc: Remove platforms/ wsp and
associated pieces") (2014).

The remaining supported CPUs use either no HTW (data_tlb_miss_bolted), or
the e6500 HTW (data_tlb_miss_e6500).

Link: https://lkml.kernel.org/r/cover.1719928057.git.christophe.leroy@csgroup.eu
Link: https://lkml.kernel.org/r/820dd1385ecc931f07b0d7a0fa827b1613917ab6.1719928057.git.christophe.leroy@csgroup.eu
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2 files changed, 1 insertions, 251 deletions

diff --git a/arch/powerpc/mm/nohash/tlb.c b/arch/powerpc/mm/nohash/tlb.c
index 5ffa0af4328a..a5bb87ec8578 100644
--- a/arch/powerpc/mm/nohash/tlb.c
+++ b/arch/powerpc/mm/nohash/tlb.c
@@ -400,9 +400,8 @@ void tlb_flush_pgtable(struct mmu_gather *tlb, unsigned long address)
 static void __init setup_page_sizes(void)
 {
 	unsigned int tlb0cfg;
-	unsigned int tlb0ps;
 	unsigned int eptcfg;
-	int i, psize;
+	int psize;
 
 #ifdef CONFIG_PPC_E500
 	unsigned int mmucfg = mfspr(SPRN_MMUCFG);
@@ -471,50 +470,6 @@ static void __init setup_page_sizes(void)
 		goto out;
 	}
 #endif
-
-	tlb0cfg = mfspr(SPRN_TLB0CFG);
-	tlb0ps = mfspr(SPRN_TLB0PS);
-	eptcfg = mfspr(SPRN_EPTCFG);
-
-	/* Look for supported direct sizes */
-	for (psize = 0; psize < MMU_PAGE_COUNT; ++psize) {
-		struct mmu_psize_def *def = &mmu_psize_defs[psize];
-
-		if (tlb0ps & (1U << (def->shift - 10)))
-			def->flags |= MMU_PAGE_SIZE_DIRECT;
-	}
-
-	/* Indirect page sizes supported ? */
-	if ((tlb0cfg & TLBnCFG_IND) == 0 ||
-	    (tlb0cfg & TLBnCFG_PT) == 0)
-		goto out;
-
-	book3e_htw_mode = PPC_HTW_IBM;
-
-	/* Now, we only deal with one IND page size for each
-	 * direct size. Hopefully all implementations today are
-	 * unambiguous, but we might want to be careful in the
-	 * future.
-	 */
-	for (i = 0; i < 3; i++) {
-		unsigned int ps, sps;
-
-		sps = eptcfg & 0x1f;
-		eptcfg >>= 5;
-		ps = eptcfg & 0x1f;
-		eptcfg >>= 5;
-		if (!ps || !sps)
-			continue;
-		for (psize = 0; psize < MMU_PAGE_COUNT; psize++) {
-			struct mmu_psize_def *def = &mmu_psize_defs[psize];
-
-			if (ps == (def->shift - 10))
-				def->flags |= MMU_PAGE_SIZE_INDIRECT;
-			if (sps == (def->shift - 10))
-				def->ind = ps + 10;
-		}
-	}
-
 out:
 	/* Cleanup array and print summary */
 	pr_info("MMU: Supported page sizes\n");
@@ -543,10 +498,6 @@ static void __init setup_mmu_htw(void)
 	 */
 
 	switch (book3e_htw_mode) {
-	case PPC_HTW_IBM:
-		patch_exception(0x1c0, exc_data_tlb_miss_htw_book3e);
-		patch_exception(0x1e0, exc_instruction_tlb_miss_htw_book3e);
-		break;
 #ifdef CONFIG_PPC_E500
 	case PPC_HTW_E6500:
 		extlb_level_exc = EX_TLB_SIZE;
@@ -577,12 +528,6 @@ static void early_init_this_mmu(void)
 		mmu_pte_psize = MMU_PAGE_2M;
 		break;
 
-	case PPC_HTW_IBM:
-		mas4 |= MAS4_INDD;
-		mas4 |=	BOOK3E_PAGESZ_1M << MAS4_TSIZED_SHIFT;
-		mmu_pte_psize = MMU_PAGE_1M;
-		break;
-
 	case PPC_HTW_NONE:
 		mas4 |=	BOOK3E_PAGESZ_4K << MAS4_TSIZED_SHIFT;
 		mmu_pte_psize = mmu_virtual_psize;
diff --git a/arch/powerpc/mm/nohash/tlb_low_64e.S b/arch/powerpc/mm/nohash/tlb_low_64e.S
index 7e0b8fe1c279..b0eb3f7eaed1 100644
--- a/arch/powerpc/mm/nohash/tlb_low_64e.S
+++ b/arch/powerpc/mm/nohash/tlb_low_64e.S
@@ -893,201 +893,6 @@ virt_page_table_tlb_miss_whacko_fault:
 	TLB_MISS_EPILOG_ERROR
 	b	exc_data_storage_book3e
 
-
-/**************************************************************
- *                                                            *
- * TLB miss handling for Book3E with hw page table support    *
- *                                                            *
- **************************************************************/
-
-
-/* Data TLB miss */
-	START_EXCEPTION(data_tlb_miss_htw)
-	TLB_MISS_PROLOG
-
-	/* Now we handle the fault proper. We only save DEAR in normal
-	 * fault case since that's the only interesting values here.
-	 * We could probably also optimize by not saving SRR0/1 in the
-	 * linear mapping case but I'll leave that for later
-	 */
-	mfspr	r14,SPRN_ESR
-	mfspr	r16,SPRN_DEAR		/* get faulting address */
-	srdi	r11,r16,44		/* get region */
-	xoris	r11,r11,0xc
-	cmpldi	cr0,r11,0		/* linear mapping ? */
-	beq	tlb_load_linear		/* yes -> go to linear map load */
-	cmpldi	cr1,r11,1		/* vmalloc mapping ? */
-
-	/* We do the user/kernel test for the PID here along with the RW test
-	 */
-	srdi.	r11,r16,60		/* Check for user region */
-	ld	r15,PACAPGD(r13)	/* Load user pgdir */
-	beq	htw_tlb_miss
-
-	/* XXX replace the RMW cycles with immediate loads + writes */
-1:	mfspr	r10,SPRN_MAS1
-	rlwinm	r10,r10,0,16,1		/* Clear TID */
-	mtspr	SPRN_MAS1,r10
-	ld	r15,PACA_KERNELPGD(r13)	/* Load kernel pgdir */
-	beq+	cr1,htw_tlb_miss
-
-	/* We got a crappy address, just fault with whatever DEAR and ESR
-	 * are here
-	 */
-	TLB_MISS_EPILOG_ERROR
-	b	exc_data_storage_book3e
-
-/* Instruction TLB miss */
-	START_EXCEPTION(instruction_tlb_miss_htw)
-	TLB_MISS_PROLOG
-
-	/* If we take a recursive fault, the second level handler may need
-	 * to know whether we are handling a data or instruction fault in
-	 * order to get to the right store fault handler. We provide that
-	 * info by keeping a crazy value for ESR in r14
-	 */
-	li	r14,-1	/* store to exception frame is done later */
-
-	/* Now we handle the fault proper. We only save DEAR in the non
-	 * linear mapping case since we know the linear mapping case will
-	 * not re-enter. We could indeed optimize and also not save SRR0/1
-	 * in the linear mapping case but I'll leave that for later
-	 *
-	 * Faulting address is SRR0 which is already in r16
-	 */
-	srdi	r11,r16,44		/* get region */
-	xoris	r11,r11,0xc
-	cmpldi	cr0,r11,0		/* linear mapping ? */
-	beq	tlb_load_linear		/* yes -> go to linear map load */
-	cmpldi	cr1,r11,1		/* vmalloc mapping ? */
-
-	/* We do the user/kernel test for the PID here along with the RW test
-	 */
-	srdi.	r11,r16,60		/* Check for user region */
-	ld	r15,PACAPGD(r13)		/* Load user pgdir */
-	beq	htw_tlb_miss
-
-	/* XXX replace the RMW cycles with immediate loads + writes */
-1:	mfspr	r10,SPRN_MAS1
-	rlwinm	r10,r10,0,16,1			/* Clear TID */
-	mtspr	SPRN_MAS1,r10
-	ld	r15,PACA_KERNELPGD(r13)		/* Load kernel pgdir */
-	beq+	htw_tlb_miss
-
-	/* We got a crappy address, just fault */
-	TLB_MISS_EPILOG_ERROR
-	b	exc_instruction_storage_book3e
-
-
-/*
- * This is the guts of the second-level TLB miss handler for direct
- * misses. We are entered with:
- *
- * r16 = virtual page table faulting address
- * r15 = PGD pointer
- * r14 = ESR
- * r13 = PACA
- * r12 = TLB exception frame in PACA
- * r11 = crap (free to use)
- * r10 = crap (free to use)
- *
- * It can be re-entered by the linear mapping miss handler. However, to
- * avoid too much complication, it will save/restore things for us
- */
-htw_tlb_miss:
-#ifdef CONFIG_PPC_KUAP
-	mfspr	r10,SPRN_MAS1
-	rlwinm.	r10,r10,0,0x3fff0000
-	beq-	htw_tlb_miss_fault /* KUAP fault */
-#endif
-	/* Search if we already have a TLB entry for that virtual address, and
-	 * if we do, bail out.
-	 *
-	 * MAS1:IND should be already set based on MAS4
-	 */
-	PPC_TLBSRX_DOT(0,R16)
-	beq	htw_tlb_miss_done
-
-	/* Now, we need to walk the page tables. First check if we are in
-	 * range.
-	 */
-	rldicl.	r10,r16,64-PGTABLE_EADDR_SIZE,PGTABLE_EADDR_SIZE+4
-	bne-	htw_tlb_miss_fault
-
-	/* Get the PGD pointer */
-	cmpldi	cr0,r15,0
-	beq-	htw_tlb_miss_fault
-
-	/* Get to PGD entry */
-	rldicl	r11,r16,64-(PGDIR_SHIFT-3),64-PGD_INDEX_SIZE-3
-	clrrdi	r10,r11,3
-	ldx	r15,r10,r15
-	cmpdi	cr0,r15,0
-	bge	htw_tlb_miss_fault
-
-	/* Get to PUD entry */
-	rldicl	r11,r16,64-(PUD_SHIFT-3),64-PUD_INDEX_SIZE-3
-	clrrdi	r10,r11,3
-	ldx	r15,r10,r15
-	cmpdi	cr0,r15,0
-	bge	htw_tlb_miss_fault
-
-	/* Get to PMD entry */
-	rldicl	r11,r16,64-(PMD_SHIFT-3),64-PMD_INDEX_SIZE-3
-	clrrdi	r10,r11,3
-	ldx	r15,r10,r15
-	cmpdi	cr0,r15,0
-	bge	htw_tlb_miss_fault
-
-	/* Ok, we're all right, we can now create an indirect entry for
-	 * a 1M or 256M page.
-	 *
-	 * The last trick is now that because we use "half" pages for
-	 * the HTW (1M IND is 2K and 256M IND is 32K) we need to account
-	 * for an added LSB bit to the RPN. For 64K pages, there is no
-	 * problem as we already use 32K arrays (half PTE pages), but for
-	 * 4K page we need to extract a bit from the virtual address and
-	 * insert it into the "PA52" bit of the RPN.
-	 */
-	rlwimi	r15,r16,32-9,20,20
-	/* Now we build the MAS:
-	 *
-	 * MAS 0   :	Fully setup with defaults in MAS4 and TLBnCFG
-	 * MAS 1   :	Almost fully setup
-	 *               - PID already updated by caller if necessary
-	 *               - TSIZE for now is base ind page size always
-	 * MAS 2   :	Use defaults
-	 * MAS 3+7 :	Needs to be done
-	 */
-	ori	r10,r15,(BOOK3E_PAGESZ_4K << MAS3_SPSIZE_SHIFT)
-
-	srdi	r16,r10,32
-	mtspr	SPRN_MAS3,r10
-	mtspr	SPRN_MAS7,r16
-
-	tlbwe
-
-htw_tlb_miss_done:
-	/* We don't bother with restoring DEAR or ESR since we know we are
-	 * level 0 and just going back to userland. They are only needed
-	 * if you are going to take an access fault
-	 */
-	TLB_MISS_EPILOG_SUCCESS
-	rfi
-
-htw_tlb_miss_fault:
-	/* We need to check if it was an instruction miss. We know this
-	 * though because r14 would contain -1
-	 */
-	cmpdi	cr0,r14,-1
-	beq	1f
-	mtspr	SPRN_DEAR,r16
-	mtspr	SPRN_ESR,r14
-	TLB_MISS_EPILOG_ERROR
-	b	exc_data_storage_book3e
-1:	TLB_MISS_EPILOG_ERROR
-	b	exc_instruction_storage_book3e
-
 /*
  * This is the guts of "any" level TLB miss handler for kernel linear
  * mapping misses. We are entered with: