1 files changed, 279 insertions, 0 deletions

diff --git a/arch/powerpc/mm/stab.c b/arch/powerpc/mm/stab.c
new file mode 100644
index 000000000000..1b83f002bf27
--- /dev/null
+++ b/arch/powerpc/mm/stab.c
@@ -0,0 +1,279 @@
+/*
+ * 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/config.h>
+#include <asm/pgtable.h>
+#include <asm/mmu.h>
+#include <asm/mmu_context.h>
+#include <asm/paca.h>
+#include <asm/cputable.h>
+#include <asm/lmb.h>
+#include <asm/abs_addr.h>
+
+struct stab_entry {
+        unsigned long esid_data;
+        unsigned long vsid_data;
+};
+
+/* Both the segment table and SLB code uses the following cache */
+#define NR_STAB_CACHE_ENTRIES 8
+DEFINE_PER_CPU(long, stab_cache_ptr);
+DEFINE_PER_CPU(long, stab_cache[NR_STAB_CACHE_ENTRIES]);
+
+/*
+ * 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) >= KERNELBASE;
+
+        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;
+                                asm volatile("eieio":::"memory");
+                                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) != KERNELBASE)
+                        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;
+        asm volatile("eieio" : : : "memory");   /* 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 (ea >= KERNELBASE) {
+                vsid = get_kernel_vsid(ea);
+        } else {
+                if ((ea >= TASK_SIZE_USER64) || (! mm))
+                        return 1;
+
+                vsid = get_vsid(mm->context.id, ea);
+        }
+
+        stab_entry = make_ste(get_paca()->stab_addr, GET_ESID(ea), vsid);
+
+        if (ea < KERNELBASE) {
+                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 = __get_cpu_var(stab_cache_ptr);
+        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");
+
+        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 < (PAGE_SIZE / sizeof(struct stab_entry));
+                     entry++, ste++) {
+                        unsigned long ea;
+                        ea = ste->esid_data & ESID_MASK;
+                        if (ea < KERNELBASE) {
+                                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");
+}
+
+extern void slb_initialize(void);
+
+/*
+ * 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 stabs_alloc(void)
+{
+        int cpu;
+
+        if (cpu_has_feature(CPU_FTR_SLB))
+                return;
+
+        for_each_cpu(cpu) {
+                unsigned long newstab;
+
+                if (cpu == 0)
+                        continue; /* stab for CPU 0 is statically allocated */
+
+                newstab = lmb_alloc_base(PAGE_SIZE, PAGE_SIZE, 1<<SID_SHIFT);
+                if (! newstab)
+                        panic("Unable to allocate segment table for CPU %d.\n",
+                              cpu);
+
+                newstab += KERNELBASE;
+
+                memset((void *)newstab, 0, PAGE_SIZE);
+
+                paca[cpu].stab_addr = newstab;
+                paca[cpu].stab_real = virt_to_abs(newstab);
+                printk(KERN_DEBUG "Segment table for CPU %d at 0x%lx virtual, 0x%lx 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(KERNELBASE);
+
+        if (cpu_has_feature(CPU_FTR_SLB)) {
+                slb_initialize();
+        } else {
+                asm volatile("isync; slbia; isync":::"memory");
+                make_ste(stab, GET_ESID(KERNELBASE), vsid);
+
+                /* Order update */
+                asm volatile("sync":::"memory");
+        }
+}