paravirt_patch.c

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/******************************************************************************
 * linux/arch/ia64/xen/paravirt_patch.c
 *
 * Copyright (c) 2008 Isaku Yamahata <yamahata at valinux co jp>
 *                    VA Linux Systems Japan K.K.
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#include <linux/init.h>
#include <asm/intrinsics.h>
#include <asm/kprobes.h>
#include <asm/paravirt.h>
#include <asm/paravirt_patch.h>

typedef union ia64_inst {
        struct {
        unsigned long long qp : 6;
        unsigned long long : 31;
        unsigned long long opcode : 4;
        unsigned long long reserved : 23;
        } generic;
        unsigned long long l;
} ia64_inst_t;

/*
 * flush_icache_range() can't be used here.
 * we are here before cpu_init() which initializes
 * ia64_i_cache_stride_shift. flush_icache_range() uses it.
 */
void __init_or_module
paravirt_flush_i_cache_range(const void *instr, unsigned long size)
{
    extern void paravirt_fc_i(const void *addr);
    unsigned long i;

    for (i = 0; i < size; i += sizeof(bundle_t))
        paravirt_fc_i(instr + i);
}

bundle_t* __init_or_module
paravirt_get_bundle(unsigned long tag)
{
    return (bundle_t *)(tag & ~3UL);
}

unsigned long __init_or_module
paravirt_get_slot(unsigned long tag)
{
    return tag & 3UL;
}

unsigned long __init_or_module
paravirt_get_num_inst(unsigned long stag, unsigned long etag)
{
    bundle_t *sbundle = paravirt_get_bundle(stag);
    unsigned long sslot = paravirt_get_slot(stag);
    bundle_t *ebundle = paravirt_get_bundle(etag);
    unsigned long eslot = paravirt_get_slot(etag);

    return (ebundle - sbundle) * 3 + eslot - sslot + 1;
}

unsigned long __init_or_module
paravirt_get_next_tag(unsigned long tag)
{
    unsigned long slot = paravirt_get_slot(tag);

    switch (slot) {
    case 0:
    case 1:
        return tag + 1;
    case 2: {
        bundle_t *bundle = paravirt_get_bundle(tag);
        return (unsigned long)(bundle + 1);
    }
    default:
        BUG();
    }
    /* NOTREACHED */
}

ia64_inst_t __init_or_module
paravirt_read_slot0(const bundle_t *bundle)
{
    ia64_inst_t inst;
    inst.l = bundle->quad0.slot0;
    return inst;
}

ia64_inst_t __init_or_module
paravirt_read_slot1(const bundle_t *bundle)
{
    ia64_inst_t inst;
    inst.l = bundle->quad0.slot1_p0 |
        ((unsigned long long)bundle->quad1.slot1_p1 << 18UL);
    return inst;
}

ia64_inst_t __init_or_module
paravirt_read_slot2(const bundle_t *bundle)
{
    ia64_inst_t inst;
    inst.l = bundle->quad1.slot2;
    return inst;
}

ia64_inst_t __init_or_module
paravirt_read_inst(unsigned long tag)
{
    bundle_t *bundle = paravirt_get_bundle(tag);
    unsigned long slot = paravirt_get_slot(tag);

    switch (slot) {
    case 0:
        return paravirt_read_slot0(bundle);
    case 1:
        return paravirt_read_slot1(bundle);
    case 2:
        return paravirt_read_slot2(bundle);
    default:
        BUG();
    }
    /* NOTREACHED */
}

void __init_or_module
paravirt_write_slot0(bundle_t *bundle, ia64_inst_t inst)
{
    bundle->quad0.slot0 = inst.l;
}

void __init_or_module
paravirt_write_slot1(bundle_t *bundle, ia64_inst_t inst)
{
    bundle->quad0.slot1_p0 = inst.l;
    bundle->quad1.slot1_p1 = inst.l >> 18UL;
}

void __init_or_module
paravirt_write_slot2(bundle_t *bundle, ia64_inst_t inst)
{
    bundle->quad1.slot2 = inst.l;
}

void __init_or_module
paravirt_write_inst(unsigned long tag, ia64_inst_t inst)
{
    bundle_t *bundle = paravirt_get_bundle(tag);
    unsigned long slot = paravirt_get_slot(tag);

    switch (slot) {
    case 0:
        paravirt_write_slot0(bundle, inst);
        break;
    case 1:
        paravirt_write_slot1(bundle, inst);
        break;
    case 2:
        paravirt_write_slot2(bundle, inst);
        break;
    default:
        BUG();
        break;
    }
    paravirt_flush_i_cache_range(bundle, sizeof(*bundle));
}

/* for debug */
void
paravirt_print_bundle(const bundle_t *bundle)
{
    const unsigned long *quad = (const unsigned long *)bundle;
    ia64_inst_t slot0 = paravirt_read_slot0(bundle);
    ia64_inst_t slot1 = paravirt_read_slot1(bundle);
    ia64_inst_t slot2 = paravirt_read_slot2(bundle);

    printk(KERN_DEBUG
           "bundle 0x%p 0x%016lx 0x%016lx\n", bundle, quad[0], quad[1]);
    printk(KERN_DEBUG
           "bundle template 0x%x\n",
           bundle->quad0.template);
    printk(KERN_DEBUG
           "slot0 0x%lx slot1_p0 0x%lx slot1_p1 0x%lx slot2 0x%lx\n",
           (unsigned long)bundle->quad0.slot0,
           (unsigned long)bundle->quad0.slot1_p0,
           (unsigned long)bundle->quad1.slot1_p1,
           (unsigned long)bundle->quad1.slot2);
    printk(KERN_DEBUG
           "slot0 0x%016llx slot1 0x%016llx slot2 0x%016llx\n",
           slot0.l, slot1.l, slot2.l);
}

static int noreplace_paravirt __init_or_module = 0;

static int __init setup_noreplace_paravirt(char *str)
{
    noreplace_paravirt = 1;
    return 1;
}
__setup("noreplace-paravirt", setup_noreplace_paravirt);

#ifdef ASM_SUPPORTED
static void __init_or_module
fill_nop_bundle(void *sbundle, void *ebundle)
{
    extern const char paravirt_nop_bundle[];
    extern const unsigned long paravirt_nop_bundle_size;

    void *bundle = sbundle;

    BUG_ON((((unsigned long)sbundle) % sizeof(bundle_t)) != 0);
    BUG_ON((((unsigned long)ebundle) % sizeof(bundle_t)) != 0);

    while (bundle < ebundle) {
        memcpy(bundle, paravirt_nop_bundle, paravirt_nop_bundle_size);

        bundle += paravirt_nop_bundle_size;
    }
}

/* helper function */
unsigned long __init_or_module
__paravirt_patch_apply_bundle(void *sbundle, void *ebundle, unsigned long type,
                  const struct paravirt_patch_bundle_elem *elems,
                  unsigned long nelems,
                  const struct paravirt_patch_bundle_elem **found)
{
    unsigned long used = 0;
    unsigned long i;

    BUG_ON((((unsigned long)sbundle) % sizeof(bundle_t)) != 0);
    BUG_ON((((unsigned long)ebundle) % sizeof(bundle_t)) != 0);

    found = NULL;
    for (i = 0; i < nelems; i++) {
        const struct paravirt_patch_bundle_elem *p = &elems[i];
        if (p->type == type) {
            unsigned long need = p->ebundle - p->sbundle;
            unsigned long room = ebundle - sbundle;

            if (found != NULL)
                *found = p;

            if (room < need) {
                /* no room to replace. skip it */
                printk(KERN_DEBUG
                       "the space is too small to put "
                       "bundles. type %ld need %ld room %ld\n",
                       type, need, room);
                break;
            }

            used = need;
            memcpy(sbundle, p->sbundle, used);
            break;
        }
    }

    return used;
}

void __init_or_module
paravirt_patch_apply_bundle(const struct paravirt_patch_site_bundle *start,
                const struct paravirt_patch_site_bundle *end)
{
    const struct paravirt_patch_site_bundle *p;

    if (noreplace_paravirt)
        return;
    if (pv_init_ops.patch_bundle == NULL)
        return;

    for (p = start; p < end; p++) {
        unsigned long used;

        used = (*pv_init_ops.patch_bundle)(p->sbundle, p->ebundle,
                           p->type);
        if (used == 0)
            continue;

        fill_nop_bundle(p->sbundle + used, p->ebundle);
        paravirt_flush_i_cache_range(p->sbundle,
                         p->ebundle - p->sbundle);
    }
    ia64_sync_i();
    ia64_srlz_i();
}

/*
 * nop.i, nop.m, nop.f instruction are same format.
 * but nop.b has differennt format.
 * This doesn't support nop.b for now.
 */
static void __init_or_module
fill_nop_inst(unsigned long stag, unsigned long etag)
{
    extern const bundle_t paravirt_nop_mfi_inst_bundle[];
    unsigned long tag;
    const ia64_inst_t nop_inst =
        paravirt_read_slot0(paravirt_nop_mfi_inst_bundle);

    for (tag = stag; tag < etag; tag = paravirt_get_next_tag(tag))
        paravirt_write_inst(tag, nop_inst);
}

void __init_or_module
paravirt_patch_apply_inst(const struct paravirt_patch_site_inst *start,
              const struct paravirt_patch_site_inst *end)
{
    const struct paravirt_patch_site_inst *p;

    if (noreplace_paravirt)
        return;
    if (pv_init_ops.patch_inst == NULL)
        return;

    for (p = start; p < end; p++) {
        unsigned long tag;
        bundle_t *sbundle;
        bundle_t *ebundle;

        tag = (*pv_init_ops.patch_inst)(p->stag, p->etag, p->type);
        if (tag == p->stag)
            continue;

        fill_nop_inst(tag, p->etag);
        sbundle = paravirt_get_bundle(p->stag);
        ebundle = paravirt_get_bundle(p->etag) + 1;
        paravirt_flush_i_cache_range(sbundle, (ebundle - sbundle) *
                         sizeof(bundle_t));
    }
    ia64_sync_i();
    ia64_srlz_i();
}
#endif /* ASM_SUPPOTED */

/* brl.cond.sptk.many <target64> X3 */
typedef union inst_x3_op {
    ia64_inst_t inst;
    struct {
        unsigned long qp: 6;
        unsigned long btyp: 3;
        unsigned long unused: 3;
        unsigned long p: 1;
        unsigned long imm20b: 20;
        unsigned long wh: 2;
        unsigned long d: 1;
        unsigned long i: 1;
        unsigned long opcode: 4;
    };
    unsigned long l;
} inst_x3_op_t;

typedef union inst_x3_imm {
    ia64_inst_t inst;
    struct {
        unsigned long unused: 2;
        unsigned long imm39: 39;
    };
    unsigned long l;
} inst_x3_imm_t;

void __init_or_module
paravirt_patch_reloc_brl(unsigned long tag, const void *target)
{
    unsigned long tag_op = paravirt_get_next_tag(tag);
    unsigned long tag_imm = tag;
    bundle_t *bundle = paravirt_get_bundle(tag);

    ia64_inst_t inst_op = paravirt_read_inst(tag_op);
    ia64_inst_t inst_imm = paravirt_read_inst(tag_imm);

    inst_x3_op_t inst_x3_op = { .l = inst_op.l };
    inst_x3_imm_t inst_x3_imm = { .l = inst_imm.l };

    unsigned long imm60 =
        ((unsigned long)target - (unsigned long)bundle) >> 4;

    BUG_ON(paravirt_get_slot(tag) != 1); /* MLX */
    BUG_ON(((unsigned long)target & (sizeof(bundle_t) - 1)) != 0);

    /* imm60[59] 1bit */
    inst_x3_op.i = (imm60 >> 59) & 1;
    /* imm60[19:0] 20bit */
    inst_x3_op.imm20b = imm60 & ((1UL << 20) - 1);
    /* imm60[58:20] 39bit */
    inst_x3_imm.imm39 = (imm60 >> 20) & ((1UL << 39) - 1);

    inst_op.l = inst_x3_op.l;
    inst_imm.l = inst_x3_imm.l;

    paravirt_write_inst(tag_op, inst_op);
    paravirt_write_inst(tag_imm, inst_imm);
}

/* br.cond.sptk.many <target25> B1 */
typedef union inst_b1 {
    ia64_inst_t inst;
    struct {
        unsigned long qp: 6;
        unsigned long btype: 3;
        unsigned long unused: 3;
        unsigned long p: 1;
        unsigned long imm20b: 20;
        unsigned long wh: 2;
        unsigned long d: 1;
        unsigned long s: 1;
        unsigned long opcode: 4;
    };
    unsigned long l;
} inst_b1_t;

void __init
paravirt_patch_reloc_br(unsigned long tag, const void *target)
{
    bundle_t *bundle = paravirt_get_bundle(tag);
    ia64_inst_t inst = paravirt_read_inst(tag);
    unsigned long target25 = (unsigned long)target - (unsigned long)bundle;
    inst_b1_t inst_b1;

    BUG_ON(((unsigned long)target & (sizeof(bundle_t) - 1)) != 0);

    inst_b1.l = inst.l;
    if (target25 & (1UL << 63))
        inst_b1.s = 1;
    else
        inst_b1.s = 0;

    inst_b1.imm20b = target25 >> 4;
    inst.l = inst_b1.l;

    paravirt_write_inst(tag, inst);
}

void __init
__paravirt_patch_apply_branch(
    unsigned long tag, unsigned long type,
    const struct paravirt_patch_branch_target *entries,
    unsigned int nr_entries)
{
    unsigned int i;
    for (i = 0; i < nr_entries; i++) {
        if (entries[i].type == type) {
            paravirt_patch_reloc_br(tag, entries[i].entry);
            break;
        }
    }
}

static void __init
paravirt_patch_apply_branch(const struct paravirt_patch_site_branch *start,
                const struct paravirt_patch_site_branch *end)
{
    const struct paravirt_patch_site_branch *p;

    if (noreplace_paravirt)
        return;
    if (pv_init_ops.patch_branch == NULL)
        return;

    for (p = start; p < end; p++)
        (*pv_init_ops.patch_branch)(p->tag, p->type);

    ia64_sync_i();
    ia64_srlz_i();
}

void __init
paravirt_patch_apply(void)
{
    extern const char __start_paravirt_bundles[];
    extern const char __stop_paravirt_bundles[];
    extern const char __start_paravirt_insts[];
    extern const char __stop_paravirt_insts[];
    extern const char __start_paravirt_branches[];
    extern const char __stop_paravirt_branches[];

    paravirt_patch_apply_bundle((const struct paravirt_patch_site_bundle *)
                    __start_paravirt_bundles,
                    (const struct paravirt_patch_site_bundle *)
                    __stop_paravirt_bundles);
    paravirt_patch_apply_inst((const struct paravirt_patch_site_inst *)
                  __start_paravirt_insts,
                  (const struct paravirt_patch_site_inst *)
                  __stop_paravirt_insts);
    paravirt_patch_apply_branch((const struct paravirt_patch_site_branch *)
                    __start_paravirt_branches,
                    (const struct paravirt_patch_site_branch *)
                    __stop_paravirt_branches);
}

/*
 * Local variables:
 * mode: C
 * c-set-style: "linux"
 * c-basic-offset: 8
 * tab-width: 8
 * indent-tabs-mode: t
 * End:
 */