powerpc: Remove STAB code

Old cpus didn't have a Segment Lookaside Buffer (SLB), instead they had
a Segment Table (STAB). Now that we've dropped support for those cpus,
we can remove the STAB support entirely.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

3 files changed, 5 insertions, 303 deletions

diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile
index 51230ee6a407..d0130fff20e5 100644
--- a/arch/powerpc/mm/Makefile
+++ b/arch/powerpc/mm/Makefile
@@ -13,9 +13,7 @@ obj-$(CONFIG_PPC_MMU_NOHASH)	+= mmu_context_nohash.o tlb_nohash.o \
 				   tlb_nohash_low.o
 obj-$(CONFIG_PPC_BOOK3E)	+= tlb_low_$(CONFIG_WORD_SIZE)e.o
 hash64-$(CONFIG_PPC_NATIVE)	:= hash_native_64.o
-obj-$(CONFIG_PPC_STD_MMU_64)	+= hash_utils_64.o \
-				   slb_low.o slb.o stab.o \
-				   $(hash64-y)
+obj-$(CONFIG_PPC_STD_MMU_64)	+= hash_utils_64.o slb_low.o slb.o $(hash64-y)
 obj-$(CONFIG_PPC_STD_MMU_32)	+= ppc_mmu_32.o
 obj-$(CONFIG_PPC_STD_MMU)	+= hash_low_$(CONFIG_WORD_SIZE).o \
 				   tlb_hash$(CONFIG_WORD_SIZE).o \
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 88fdd9d25077..fb8bea71327d 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -821,21 +821,15 @@ static void __init htab_initialize(void)
 
 void __init early_init_mmu(void)
 {
-	/* Setup initial STAB address in the PACA */
-	get_paca()->stab_real = __pa((u64)&initial_stab);
-	get_paca()->stab_addr = (u64)&initial_stab;
-
 	/* Initialize the MMU Hash table and create the linear mapping
-	 * of memory. Has to be done before stab/slb initialization as
-	 * this is currently where the page size encoding is obtained
+	 * of memory. Has to be done before SLB initialization as this is
+	 * currently where the page size encoding is obtained.
 	 */
 	htab_initialize();
 
-	/* Initialize stab / SLB management */
+	/* Initialize SLB management */
 	if (mmu_has_feature(MMU_FTR_SLB))
 		slb_initialize();
-	else
-		stab_initialize(get_paca()->stab_real);
 }
 
 #ifdef CONFIG_SMP
@@ -845,13 +839,9 @@ void early_init_mmu_secondary(void)
 	if (!firmware_has_feature(FW_FEATURE_LPAR))
 		mtspr(SPRN_SDR1, _SDR1);
 
-	/* Initialize STAB/SLB. We use a virtual address as it works
-	 * in real mode on pSeries.
-	 */
+	/* Initialize SLB */
 	if (mmu_has_feature(MMU_FTR_SLB))
 		slb_initialize();
-	else
-		stab_initialize(get_paca()->stab_addr);
 }
 #endif /* CONFIG_SMP */
 
diff --git a/arch/powerpc/mm/stab.c b/arch/powerpc/mm/stab.c
deleted file mode 100644
index 3f8efa6f2997..000000000000
--- a/arch/powerpc/mm/stab.c
+++ /dev/null
@@ -1,286 +0,0 @@
-/*
- * PowerPC64 Segment Translation Support.
- *
- * Dave Engebretsen and Mike Corrigan {engebret|mikejc}@us.ibm.com
- *    Copyright (c) 2001 Dave Engebretsen
- *
- * Copyright (C) 2002 Anton Blanchard <anton@au.ibm.com>, IBM
- *
- *      This program is free software; you can redistribute it and/or
- *      modify it under the terms of the GNU General Public License
- *      as published by the Free Software Foundation; either version
- *      2 of the License, or (at your option) any later version.
- */
-
-#include <linux/memblock.h>
-
-#include <asm/pgtable.h>
-#include <asm/mmu.h>
-#include <asm/mmu_context.h>
-#include <asm/paca.h>
-#include <asm/cputable.h>
-#include <asm/prom.h>
-
-struct stab_entry {
-	unsigned long esid_data;
-	unsigned long vsid_data;
-};
-
-#define NR_STAB_CACHE_ENTRIES 8
-static DEFINE_PER_CPU(long, stab_cache_ptr);
-static DEFINE_PER_CPU(long [NR_STAB_CACHE_ENTRIES], stab_cache);
-
-/*
- * Create a segment table entry for the given esid/vsid pair.
- */
-static int make_ste(unsigned long stab, unsigned long esid, unsigned long vsid)
-{
-	unsigned long esid_data, vsid_data;
-	unsigned long entry, group, old_esid, castout_entry, i;
-	unsigned int global_entry;
-	struct stab_entry *ste, *castout_ste;
-	unsigned long kernel_segment = (esid << SID_SHIFT) >= PAGE_OFFSET;
-
-	vsid_data = vsid << STE_VSID_SHIFT;
-	esid_data = esid << SID_SHIFT | STE_ESID_KP | STE_ESID_V;
-	if (! kernel_segment)
-		esid_data |= STE_ESID_KS;
-
-	/* Search the primary group first. */
-	global_entry = (esid & 0x1f) << 3;
-	ste = (struct stab_entry *)(stab | ((esid & 0x1f) << 7));
-
-	/* Find an empty entry, if one exists. */
-	for (group = 0; group < 2; group++) {
-		for (entry = 0; entry < 8; entry++, ste++) {
-			if (!(ste->esid_data & STE_ESID_V)) {
-				ste->vsid_data = vsid_data;
-				eieio();
-				ste->esid_data = esid_data;
-				return (global_entry | entry);
-			}
-		}
-		/* Now search the secondary group. */
-		global_entry = ((~esid) & 0x1f) << 3;
-		ste = (struct stab_entry *)(stab | (((~esid) & 0x1f) << 7));
-	}
-
-	/*
-	 * Could not find empty entry, pick one with a round robin selection.
-	 * Search all entries in the two groups.
-	 */
-	castout_entry = get_paca()->stab_rr;
-	for (i = 0; i < 16; i++) {
-		if (castout_entry < 8) {
-			global_entry = (esid & 0x1f) << 3;
-			ste = (struct stab_entry *)(stab | ((esid & 0x1f) << 7));
-			castout_ste = ste + castout_entry;
-		} else {
-			global_entry = ((~esid) & 0x1f) << 3;
-			ste = (struct stab_entry *)(stab | (((~esid) & 0x1f) << 7));
-			castout_ste = ste + (castout_entry - 8);
-		}
-
-		/* Dont cast out the first kernel segment */
-		if ((castout_ste->esid_data & ESID_MASK) != PAGE_OFFSET)
-			break;
-
-		castout_entry = (castout_entry + 1) & 0xf;
-	}
-
-	get_paca()->stab_rr = (castout_entry + 1) & 0xf;
-
-	/* Modify the old entry to the new value. */
-
-	/* Force previous translations to complete. DRENG */
-	asm volatile("isync" : : : "memory");
-
-	old_esid = castout_ste->esid_data >> SID_SHIFT;
-	castout_ste->esid_data = 0;		/* Invalidate old entry */
-
-	asm volatile("sync" : : : "memory");    /* Order update */
-
-	castout_ste->vsid_data = vsid_data;
-	eieio();				/* Order update */
-	castout_ste->esid_data = esid_data;
-
-	asm volatile("slbie  %0" : : "r" (old_esid << SID_SHIFT));
-	/* Ensure completion of slbie */
-	asm volatile("sync" : : : "memory");
-
-	return (global_entry | (castout_entry & 0x7));
-}
-
-/*
- * Allocate a segment table entry for the given ea and mm
- */
-static int __ste_allocate(unsigned long ea, struct mm_struct *mm)
-{
-	unsigned long vsid;
-	unsigned char stab_entry;
-	unsigned long offset;
-
-	/* Kernel or user address? */
-	if (is_kernel_addr(ea)) {
-		vsid = get_kernel_vsid(ea, MMU_SEGSIZE_256M);
-	} else {
-		if ((ea >= TASK_SIZE_USER64) || (! mm))
-			return 1;
-
-		vsid = get_vsid(mm->context.id, ea, MMU_SEGSIZE_256M);
-	}
-
-	stab_entry = make_ste(get_paca()->stab_addr, GET_ESID(ea), vsid);
-
-	if (!is_kernel_addr(ea)) {
-		offset = __get_cpu_var(stab_cache_ptr);
-		if (offset < NR_STAB_CACHE_ENTRIES)
-			__get_cpu_var(stab_cache[offset++]) = stab_entry;
-		else
-			offset = NR_STAB_CACHE_ENTRIES+1;
-		__get_cpu_var(stab_cache_ptr) = offset;
-
-		/* Order update */
-		asm volatile("sync":::"memory");
-	}
-
-	return 0;
-}
-
-int ste_allocate(unsigned long ea)
-{
-	return __ste_allocate(ea, current->mm);
-}
-
-/*
- * Do the segment table work for a context switch: flush all user
- * entries from the table, then preload some probably useful entries
- * for the new task
- */
-void switch_stab(struct task_struct *tsk, struct mm_struct *mm)
-{
-	struct stab_entry *stab = (struct stab_entry *) get_paca()->stab_addr;
-	struct stab_entry *ste;
-	unsigned long offset;
-	unsigned long pc = KSTK_EIP(tsk);
-	unsigned long stack = KSTK_ESP(tsk);
-	unsigned long unmapped_base;
-
-	/* Force previous translations to complete. DRENG */
-	asm volatile("isync" : : : "memory");
-
-	/*
-	 * We need interrupts hard-disabled here, not just soft-disabled,
-	 * so that a PMU interrupt can't occur, which might try to access
-	 * user memory (to get a stack trace) and possible cause an STAB miss
-	 * which would update the stab_cache/stab_cache_ptr per-cpu variables.
-	 */
-	hard_irq_disable();
-
-	offset = __get_cpu_var(stab_cache_ptr);
-	if (offset <= NR_STAB_CACHE_ENTRIES) {
-		int i;
-
-		for (i = 0; i < offset; i++) {
-			ste = stab + __get_cpu_var(stab_cache[i]);
-			ste->esid_data = 0; /* invalidate entry */
-		}
-	} else {
-		unsigned long entry;
-
-		/* Invalidate all entries. */
-		ste = stab;
-
-		/* Never flush the first entry. */
-		ste += 1;
-		for (entry = 1;
-		     entry < (HW_PAGE_SIZE / sizeof(struct stab_entry));
-		     entry++, ste++) {
-			unsigned long ea;
-			ea = ste->esid_data & ESID_MASK;
-			if (!is_kernel_addr(ea)) {
-				ste->esid_data = 0;
-			}
-		}
-	}
-
-	asm volatile("sync; slbia; sync":::"memory");
-
-	__get_cpu_var(stab_cache_ptr) = 0;
-
-	/* Now preload some entries for the new task */
-	if (test_tsk_thread_flag(tsk, TIF_32BIT))
-		unmapped_base = TASK_UNMAPPED_BASE_USER32;
-	else
-		unmapped_base = TASK_UNMAPPED_BASE_USER64;
-
-	__ste_allocate(pc, mm);
-
-	if (GET_ESID(pc) == GET_ESID(stack))
-		return;
-
-	__ste_allocate(stack, mm);
-
-	if ((GET_ESID(pc) == GET_ESID(unmapped_base))
-	    || (GET_ESID(stack) == GET_ESID(unmapped_base)))
-		return;
-
-	__ste_allocate(unmapped_base, mm);
-
-	/* Order update */
-	asm volatile("sync" : : : "memory");
-}
-
-/*
- * Allocate segment tables for secondary CPUs.  These must all go in
- * the first (bolted) segment, so that do_stab_bolted won't get a
- * recursive segment miss on the segment table itself.
- */
-void __init stabs_alloc(void)
-{
-	int cpu;
-
-	if (mmu_has_feature(MMU_FTR_SLB))
-		return;
-
-	for_each_possible_cpu(cpu) {
-		unsigned long newstab;
-
-		if (cpu == 0)
-			continue; /* stab for CPU 0 is statically allocated */
-
-		newstab = memblock_alloc_base(HW_PAGE_SIZE, HW_PAGE_SIZE,
-					 1<<SID_SHIFT);
-		newstab = (unsigned long)__va(newstab);
-
-		memset((void *)newstab, 0, HW_PAGE_SIZE);
-
-		paca[cpu].stab_addr = newstab;
-		paca[cpu].stab_real = __pa(newstab);
-		printk(KERN_INFO "Segment table for CPU %d at 0x%llx "
-		       "virtual, 0x%llx absolute\n",
-		       cpu, paca[cpu].stab_addr, paca[cpu].stab_real);
-	}
-}
-
-/*
- * Build an entry for the base kernel segment and put it into
- * the segment table or SLB.  All other segment table or SLB
- * entries are faulted in.
- */
-void stab_initialize(unsigned long stab)
-{
-	unsigned long vsid = get_kernel_vsid(PAGE_OFFSET, MMU_SEGSIZE_256M);
-	unsigned long stabreal;
-
-	asm volatile("isync; slbia; isync":::"memory");
-	make_ste(stab, GET_ESID(PAGE_OFFSET), vsid);
-
-	/* Order update */
-	asm volatile("sync":::"memory");
-
-	/* Set ASR */
-	stabreal = get_paca()->stab_real | 0x1ul;
-
-	mtspr(SPRN_ASR, stabreal);
-}