/*
 * IA-64-specific support for kernel module loader.
 *
 * Copyright (C) 2003 Hewlett-Packard Co
 *      David Mosberger-Tang <davidm@hpl.hp.com>
 *
 * Loosely based on patch by Rusty Russell.
 */

/* relocs tested so far:

   DIR64LSB
   FPTR64LSB
   GPREL22
   LDXMOV
   LDXMOV
   LTOFF22
   LTOFF22X
   LTOFF22X
   LTOFF_FPTR22
   PCREL21B     (for br.call only; br.cond is not supported out of modules!)
   PCREL60B     (for brl.cond only; brl.call is not supported for modules!)
   PCREL64LSB
   SECREL32LSB
   SEGREL64LSB
 */


#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/elf.h>
#include <linux/moduleloader.h>
#include <linux/string.h>
#include <linux/vmalloc.h>

#include <asm/patch.h>
#include <asm/unaligned.h>

#define ARCH_MODULE_DEBUG 0

#if ARCH_MODULE_DEBUG
# define DEBUGP printk
# define inline
#else
# define DEBUGP(fmt , a...)
#endif

#ifdef CONFIG_ITANIUM
# define USE_BRL        0
#else
# define USE_BRL        1
#endif

#define MAX_LTOFF       ((uint64_t) (1 << 22))  /* max. allowable linkage-table offset */

/* Define some relocation helper macros/types: */

#define FORMAT_SHIFT    0
#define FORMAT_BITS     3
#define FORMAT_MASK     ((1 << FORMAT_BITS) - 1)
#define VALUE_SHIFT     3
#define VALUE_BITS      5
#define VALUE_MASK      ((1 << VALUE_BITS) - 1)

enum reloc_target_format {
        /* direct encoded formats: */
        RF_NONE = 0,
        RF_INSN14 = 1,
        RF_INSN22 = 2,
        RF_INSN64 = 3,
        RF_32MSB = 4,
        RF_32LSB = 5,
        RF_64MSB = 6,
        RF_64LSB = 7,

        /* formats that cannot be directly decoded: */
        RF_INSN60,
        RF_INSN21B,     /* imm21 form 1 */
        RF_INSN21M,     /* imm21 form 2 */
        RF_INSN21F      /* imm21 form 3 */
};

enum reloc_value_formula {
        RV_DIRECT = 4,          /* S + A */
        RV_GPREL = 5,           /* @gprel(S + A) */
        RV_LTREL = 6,           /* @ltoff(S + A) */
        RV_PLTREL = 7,          /* @pltoff(S + A) */
        RV_FPTR = 8,            /* @fptr(S + A) */
        RV_PCREL = 9,           /* S + A - P */
        RV_LTREL_FPTR = 10,     /* @ltoff(@fptr(S + A)) */
        RV_SEGREL = 11,         /* @segrel(S + A) */
        RV_SECREL = 12,         /* @secrel(S + A) */
        RV_BDREL = 13,          /* BD + A */
        RV_LTV = 14,            /* S + A (like RV_DIRECT, except frozen at static link-time) */
        RV_PCREL2 = 15,         /* S + A - P */
        RV_SPECIAL = 16,        /* various (see below) */
        RV_RSVD17 = 17,
        RV_TPREL = 18,          /* @tprel(S + A) */
        RV_LTREL_TPREL = 19,    /* @ltoff(@tprel(S + A)) */
        RV_DTPMOD = 20,         /* @dtpmod(S + A) */
        RV_LTREL_DTPMOD = 21,   /* @ltoff(@dtpmod(S + A)) */
        RV_DTPREL = 22,         /* @dtprel(S + A) */
        RV_LTREL_DTPREL = 23,   /* @ltoff(@dtprel(S + A)) */
        RV_RSVD24 = 24,
        RV_RSVD25 = 25,
        RV_RSVD26 = 26,
        RV_RSVD27 = 27
        /* 28-31 reserved for implementation-specific purposes.  */
};

#define N(reloc)        [R_IA64_##reloc] = #reloc

static const char *reloc_name[256] = {
        N(NONE),                N(IMM14),               N(IMM22),               N(IMM64),
        N(DIR32MSB),            N(DIR32LSB),            N(DIR64MSB),            N(DIR64LSB),
        N(GPREL22),             N(GPREL64I),            N(GPREL32MSB),          N(GPREL32LSB),
        N(GPREL64MSB),          N(GPREL64LSB),          N(LTOFF22),             N(LTOFF64I),
        N(PLTOFF22),            N(PLTOFF64I),           N(PLTOFF64MSB),         N(PLTOFF64LSB),
        N(FPTR64I),             N(FPTR32MSB),           N(FPTR32LSB),           N(FPTR64MSB),
        N(FPTR64LSB),           N(PCREL60B),            N(PCREL21B),            N(PCREL21M),
        N(PCREL21F),            N(PCREL32MSB),          N(PCREL32LSB),          N(PCREL64MSB),
        N(PCREL64LSB),          N(LTOFF_FPTR22),        N(LTOFF_FPTR64I),       N(LTOFF_FPTR32MSB),
        N(LTOFF_FPTR32LSB),     N(LTOFF_FPTR64MSB),     N(LTOFF_FPTR64LSB),     N(SEGREL32MSB),
        N(SEGREL32LSB),         N(SEGREL64MSB),         N(SEGREL64LSB),         N(SECREL32MSB),
        N(SECREL32LSB),         N(SECREL64MSB),         N(SECREL64LSB),         N(REL32MSB),
        N(REL32LSB),            N(REL64MSB),            N(REL64LSB),            N(LTV32MSB),
        N(LTV32LSB),            N(LTV64MSB),            N(LTV64LSB),            N(PCREL21BI),
        N(PCREL22),             N(PCREL64I),            N(IPLTMSB),             N(IPLTLSB),
        N(COPY),                N(LTOFF22X),            N(LDXMOV),              N(TPREL14),
        N(TPREL22),             N(TPREL64I),            N(TPREL64MSB),          N(TPREL64LSB),
        N(LTOFF_TPREL22),       N(DTPMOD64MSB),         N(DTPMOD64LSB),         N(LTOFF_DTPMOD22),
        N(DTPREL14),            N(DTPREL22),            N(DTPREL64I),           N(DTPREL32MSB),
        N(DTPREL32LSB),         N(DTPREL64MSB),         N(DTPREL64LSB),         N(LTOFF_DTPREL22)
};

#undef N

/* Opaque struct for insns, to protect against derefs. */
struct insn;

static inline uint64_t
bundle (const struct insn *insn)
{
        return (uint64_t) insn & ~0xfUL;
}

static inline int
slot (const struct insn *insn)
{
        return (uint64_t) insn & 0x3;
}

static int
apply_imm64 (struct module *mod, struct insn *insn, uint64_t val)
{
        if (slot(insn) != 2) {
                printk(KERN_ERR "%s: invalid slot number %d for IMM64\n",
                       mod->name, slot(insn));
                return 0;
        }
        ia64_patch_imm64((u64) insn, val);
        return 1;
}

static int
apply_imm60 (struct module *mod, struct insn *insn, uint64_t val)
{
        if (slot(insn) != 2) {
                printk(KERN_ERR "%s: invalid slot number %d for IMM60\n",
                       mod->name, slot(insn));
                return 0;
        }
        if (val + ((uint64_t) 1 << 59) >= (1UL << 60)) {
                printk(KERN_ERR "%s: value %ld out of IMM60 range\n", mod->name, (int64_t) val);
                return 0;
        }
        ia64_patch_imm60((u64) insn, val);
        return 1;
}

static int
apply_imm22 (struct module *mod, struct insn *insn, uint64_t val)
{
        if (val + (1 << 21) >= (1 << 22)) {
                printk(KERN_ERR "%s: value %li out of IMM22 range\n", mod->name, (int64_t)val);
                return 0;
        }
        ia64_patch((u64) insn, 0x01fffcfe000UL, (  ((val & 0x200000UL) << 15) /* bit 21 -> 36 */
                                                 | ((val & 0x1f0000UL) <<  6) /* bit 16 -> 22 */
                                                 | ((val & 0x00ff80UL) << 20) /* bit  7 -> 27 */
                                                 | ((val & 0x00007fUL) << 13) /* bit  0 -> 13 */));
        return 1;
}

static int
apply_imm21b (struct module *mod, struct insn *insn, uint64_t val)
{
        if (val + (1 << 20) >= (1 << 21)) {
                printk(KERN_ERR "%s: value %li out of IMM21b range\n", mod->name, (int64_t)val);
                return 0;
        }
        ia64_patch((u64) insn, 0x11ffffe000UL, (  ((val & 0x100000UL) << 16) /* bit 20 -> 36 */
                                                | ((val & 0x0fffffUL) << 13) /* bit  0 -> 13 */));
        return 1;
}

#if USE_BRL

struct plt_entry {
        /* Three instruction bundles in PLT. */
        unsigned char bundle[2][16];
};

static const struct plt_entry ia64_plt_template = {
        {
                {
                        0x04, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0 */
                        0x00, 0x00, 0x00, 0x00, 0x00, 0x20, /*       movl gp=TARGET_GP */
                        0x00, 0x00, 0x00, 0x60
                },
                {
                        0x05, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0 */
                        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /*       brl.many gp=TARGET_GP */
                        0x08, 0x00, 0x00, 0xc0
                }
        }
};

static int
patch_plt (struct module *mod, struct plt_entry *plt, long target_ip, unsigned long target_gp)
{
        if (apply_imm64(mod, (struct insn *) (plt->bundle[0] + 2), target_gp)
            && apply_imm60(mod, (struct insn *) (plt->bundle[1] + 2),
                           (target_ip - (int64_t) plt->bundle[1]) / 16))
                return 1;
        return 0;
}

unsigned long
plt_target (struct plt_entry *plt)
{
        uint64_t b0, b1, *b = (uint64_t *) plt->bundle[1];
        long off;

        b0 = b[0]; b1 = b[1];
        off = (  ((b1 & 0x00fffff000000000UL) >> 36)            /* imm20b -> bit 0 */
               | ((b0 >> 48) << 20) | ((b1 & 0x7fffffUL) << 36) /* imm39 -> bit 20 */
               | ((b1 & 0x0800000000000000UL) << 0));           /* i -> bit 59 */
        return (long) plt->bundle[1] + 16*off;
}

#else /* !USE_BRL */

struct plt_entry {
        /* Three instruction bundles in PLT. */
        unsigned char bundle[3][16];
};

static const struct plt_entry ia64_plt_template = {
        {
                {
                        0x05, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0 */
                        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /*       movl r16=TARGET_IP */
                        0x02, 0x00, 0x00, 0x60
                },
                {
                        0x04, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0 */
                        0x00, 0x00, 0x00, 0x00, 0x00, 0x20, /*       movl gp=TARGET_GP */
                        0x00, 0x00, 0x00, 0x60
                },
                {
                        0x11, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MIB] nop.m 0 */
                        0x60, 0x80, 0x04, 0x80, 0x03, 0x00, /*       mov b6=r16 */
                        0x60, 0x00, 0x80, 0x00              /*       br.few b6 */
                }
        }
};

static int
patch_plt (struct module *mod, struct plt_entry *plt, long target_ip, unsigned long target_gp)
{
        if (apply_imm64(mod, (struct insn *) (plt->bundle[0] + 2), target_ip)
            && apply_imm64(mod, (struct insn *) (plt->bundle[1] + 2), target_gp))
                return 1;
        return 0;
}

unsigned long
plt_target (struct plt_entry *plt)
{
        uint64_t b0, b1, *b = (uint64_t *) plt->bundle[0];

        b0 = b[0]; b1 = b[1];
        return (  ((b1 & 0x000007f000000000) >> 36)             /* imm7b -> bit 0 */
                | ((b1 & 0x07fc000000000000) >> 43)             /* imm9d -> bit 7 */
                | ((b1 & 0x0003e00000000000) >> 29)             /* imm5c -> bit 16 */
                | ((b1 & 0x0000100000000000) >> 23)             /* ic -> bit 21 */
                | ((b0 >> 46) << 22) | ((b1 & 0x7fffff) << 40)  /* imm41 -> bit 22 */
                | ((b1 & 0x0800000000000000) <<  4));           /* i -> bit 63 */
}

#endif /* !USE_BRL */

void *
module_alloc (unsigned long size)
{
        if (!size)
                return NULL;
        return vmalloc(size);
}

void
module_free (struct module *mod, void *module_region)
{
        if (mod && mod->arch.init_unw_table &&
            module_region == mod->module_init) {
                unw_remove_unwind_table(mod->arch.init_unw_table);
                mod->arch.init_unw_table = NULL;
        }
        vfree(module_region);
}

/* Have we already seen one of these relocations? */
/* FIXME: we could look in other sections, too --RR */
static int
duplicate_reloc (const Elf64_Rela *rela, unsigned int num)
{
        unsigned int i;

        for (i = 0; i < num; i++) {
                if (rela[i].r_info == rela[num].r_info && rela[i].r_addend == rela[num].r_addend)
                        return 1;
        }
        return 0;
}

/* Count how many GOT entries we may need */
static unsigned int
count_gots (const Elf64_Rela *rela, unsigned int num)
{
        unsigned int i, ret = 0;

        /* Sure, this is order(n^2), but it's usually short, and not
           time critical */
        for (i = 0; i < num; i++) {
                switch (ELF64_R_TYPE(rela[i].r_info)) {
                      case R_IA64_LTOFF22:
                      case R_IA64_LTOFF22X:
                      case R_IA64_LTOFF64I:
                      case R_IA64_LTOFF_FPTR22:
                      case R_IA64_LTOFF_FPTR64I:
                      case R_IA64_LTOFF_FPTR32MSB:
                      case R_IA64_LTOFF_FPTR32LSB:
                      case R_IA64_LTOFF_FPTR64MSB:
                      case R_IA64_LTOFF_FPTR64LSB:
                        if (!duplicate_reloc(rela, i))
                                ret++;
                        break;
                }
        }
        return ret;
}

/* Count how many PLT entries we may need */
static unsigned int
count_plts (const Elf64_Rela *rela, unsigned int num)
{
        unsigned int i, ret = 0;

        /* Sure, this is order(n^2), but it's usually short, and not
           time critical */
        for (i = 0; i < num; i++) {
                switch (ELF64_R_TYPE(rela[i].r_info)) {
                      case R_IA64_PCREL21B:
                      case R_IA64_PLTOFF22:
                      case R_IA64_PLTOFF64I:
                      case R_IA64_PLTOFF64MSB:
                      case R_IA64_PLTOFF64LSB:
                      case R_IA64_IPLTMSB:
                      case R_IA64_IPLTLSB:
                        if (!duplicate_reloc(rela, i))
                                ret++;
                        break;
                }
        }
        return ret;
}

/* We need to create an function-descriptors for any internal function
   which is referenced. */
static unsigned int
count_fdescs (const Elf64_Rela *rela, unsigned int num)
{
        unsigned int i, ret = 0;

        /* Sure, this is order(n^2), but it's usually short, and not time critical.  */
        for (i = 0; i < num; i++) {
                switch (ELF64_R_TYPE(rela[i].r_info)) {
                      case R_IA64_FPTR64I:
                      case R_IA64_FPTR32LSB:
                      case R_IA64_FPTR32MSB:
                      case R_IA64_FPTR64LSB:
                      case R_IA64_FPTR64MSB:
                      case R_IA64_LTOFF_FPTR22:
                      case R_IA64_LTOFF_FPTR32LSB:
                      case R_IA64_LTOFF_FPTR32MSB:
                      case R_IA64_LTOFF_FPTR64I:
                      case R_IA64_LTOFF_FPTR64LSB:
                      case R_IA64_LTOFF_FPTR64MSB:
                      case R_IA64_IPLTMSB:
                      case R_IA64_IPLTLSB:
                        /*
                         * Jumps to static functions sometimes go straight to their
                         * offset.  Of course, that may not be possible if the jump is
                         * from init -> core or vice. versa, so we need to generate an
                         * FDESC (and PLT etc) for that.
                         */
                      case R_IA64_PCREL21B:
                        if (!duplicate_reloc(rela, i))
                                ret++;
                        break;
                }
        }
        return ret;
}

int
module_frob_arch_sections (Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, char *secstrings,
                           struct module *mod)
{
        unsigned long core_plts = 0, init_plts = 0, gots = 0, fdescs = 0;
        Elf64_Shdr *s, *sechdrs_end = sechdrs + ehdr->e_shnum;

        /*
         * To store the PLTs and function-descriptors, we expand the .text section for
         * core module-code and the .init.text section for initialization code.
         */
        for (s = sechdrs; s < sechdrs_end; ++s)
                if (strcmp(".core.plt", secstrings + s->sh_name) == 0)
                        mod->arch.core_plt = s;
                else if (strcmp(".init.plt", secstrings + s->sh_name) == 0)
                        mod->arch.init_plt = s;
                else if (strcmp(".got", secstrings + s->sh_name) == 0)
                        mod->arch.got = s;
                else if (strcmp(".opd", secstrings + s->sh_name) == 0)
                        mod->arch.opd = s;
                else if (strcmp(".IA_64.unwind", secstrings + s->sh_name) == 0)
                        mod->arch.unwind = s;

        if (!mod->arch.core_plt || !mod->arch.init_plt || !mod->arch.got || !mod->arch.opd) {
                printk(KERN_ERR "%s: sections missing\n", mod->name);
                return -ENOEXEC;
        }

        /* GOT and PLTs can occur in any relocated section... */
        for (s = sechdrs + 1; s < sechdrs_end; ++s) {
                const Elf64_Rela *rels = (void *)ehdr + s->sh_offset;
                unsigned long numrels = s->sh_size/sizeof(Elf64_Rela);

                if (s->sh_type != SHT_RELA)
                        continue;

                gots += count_gots(rels, numrels);
                fdescs += count_fdescs(rels, numrels);
                if (strstr(secstrings + s->sh_name, ".init"))
                        init_plts += count_plts(rels, numrels);
                else
                        core_plts += count_plts(rels, numrels);
        }

        mod->arch.core_plt->sh_type = SHT_NOBITS;
        mod->arch.core_plt->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
        mod->arch.core_plt->sh_addralign = 16;
        mod->arch.core_plt->sh_size = core_plts * sizeof(struct plt_entry);
        mod->arch.init_plt->sh_type = SHT_NOBITS;
        mod->arch.init_plt->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
        mod->arch.init_plt->sh_addralign = 16;
        mod->arch.init_plt->sh_size = init_plts * sizeof(struct plt_entry);
        mod->arch.got->sh_type = SHT_NOBITS;
        mod->arch.got->sh_flags = ARCH_SHF_SMALL | SHF_ALLOC;
        mod->arch.got->sh_addralign = 8;
        mod->arch.got->sh_size = gots * sizeof(struct got_entry);
        mod->arch.opd->sh_type = SHT_NOBITS;
        mod->arch.opd->sh_flags = SHF_ALLOC;
        mod->arch.opd->sh_addralign = 8;
        mod->arch.opd->sh_size = fdescs * sizeof(struct fdesc);
        DEBUGP("%s: core.plt=%lx, init.plt=%lx, got=%lx, fdesc=%lx\n",
               __func__, mod->arch.core_plt->sh_size, mod->arch.init_plt->sh_size,
               mod->arch.got->sh_size, mod->arch.opd->sh_size);
        return 0;
}

static inline int
in_init (const struct module *mod, uint64_t addr)
{
        return addr - (uint64_t) mod->module_init < mod->init_size;
}

static inline int
in_core (const struct module *mod, uint64_t addr)
{
        return addr - (uint64_t) mod->module_core < mod->core_size;
}

static inline int
is_internal (const struct module *mod, uint64_t value)
{
        return in_init(mod, value) || in_core(mod, value);
}

/*
 * Get gp-relative offset for the linkage-table entry of VALUE.
 */
static uint64_t
get_ltoff (struct module *mod, uint64_t value, int *okp)
{
        struct got_entry *got, *e;

        if (!*okp)
                return 0;

        got = (void *) mod->arch.got->sh_addr;
        for (e = got; e < got + mod->arch.next_got_entry; ++e)
                if (e->val == value)
                        goto found;

        /* Not enough GOT entries? */
        if (e >= (struct got_entry *) (mod->arch.got->sh_addr + mod->arch.got->sh_size))
                BUG();

        e->val = value;
        ++mod->arch.next_got_entry;
  found:
        return (uint64_t) e - mod->arch.gp;
}

static inline int
gp_addressable (struct module *mod, uint64_t value)
{
        return value - mod->arch.gp + MAX_LTOFF/2 < MAX_LTOFF;
}

/* Get PC-relative PLT entry for this value.  Returns 0 on failure. */
static uint64_t
get_plt (struct module *mod, const struct insn *insn, uint64_t value, int *okp)
{
        struct plt_entry *plt, *plt_end;
        uint64_t target_ip, target_gp;

        if (!*okp)
                return 0;

        if (in_init(mod, (uint64_t) insn)) {
                plt = (void *) mod->arch.init_plt->sh_addr;
                plt_end = (void *) plt + mod->arch.init_plt->sh_size;
        } else {
                plt = (void *) mod->arch.core_plt->sh_addr;
                plt_end = (void *) plt + mod->arch.core_plt->sh_size;
        }

        /* "value" is a pointer to a function-descriptor; fetch the target ip/gp from it: */
        target_ip = ((uint64_t *) value)[0];
        target_gp = ((uint64_t *) value)[1];

        /* Look for existing PLT entry. */
        while (plt->bundle[0][0]) {
                if (plt_target(plt) == target_ip)
                        goto found;
                if (++plt >= plt_end)
                        BUG();
        }
        *plt = ia64_plt_template;
        if (!patch_plt(mod, plt, target_ip, target_gp)) {
                *okp = 0;
                return 0;
        }
#if ARCH_MODULE_DEBUG
        if (plt_target(plt) != target_ip) {
                printk("%s: mistargeted PLT: wanted %lx, got %lx\n",
                       __func__, target_ip, plt_target(plt));
                *okp = 0;
                return 0;
        }
#endif
  found:
        return (uint64_t) plt;
}

/* Get function descriptor for VALUE. */
static uint64_t
get_fdesc (struct module *mod, uint64_t value, int *okp)
{
        struct fdesc *fdesc = (void *) mod->arch.opd->sh_addr;

        if (!*okp)
                return 0;

        if (!value) {
                printk(KERN_ERR "%s: fdesc for zero requested!\n", mod->name);
                return 0;
        }

        if (!is_internal(mod, value))
                /*
                 * If it's not a module-local entry-point, "value" already points to a
                 * function-descriptor.
                 */
                return value;

        /* Look for existing function descriptor. */
        while (fdesc->ip) {
                if (fdesc->ip == value)
                        return (uint64_t)fdesc;
                if ((uint64_t) ++fdesc >= mod->arch.opd->sh_addr + mod->arch.opd->sh_size)
                        BUG();
        }

        /* Create new one */
        fdesc->ip = value;
        fdesc->gp = mod->arch.gp;
        return (uint64_t) fdesc;
}

static inline int
do_reloc (struct module *mod, uint8_t r_type, Elf64_Sym *sym, uint64_t addend,
          Elf64_Shdr *sec, void *location)
{
        enum reloc_target_format format = (r_type >> FORMAT_SHIFT) & FORMAT_MASK;
        enum reloc_value_formula formula = (r_type >> VALUE_SHIFT) & VALUE_MASK;
        uint64_t val;
        int ok = 1;

        val = sym->st_value + addend;

        switch (formula) {
              case RV_SEGREL:   /* segment base is arbitrarily chosen to be 0 for kernel modules */
              case RV_DIRECT:
                break;

              case RV_GPREL:      val -= mod->arch.gp; break;
              case RV_LTREL:      val = get_ltoff(mod, val, &ok); break;
              case RV_PLTREL:     val = get_plt(mod, location, val, &ok); break;
              case RV_FPTR:       val = get_fdesc(mod, val, &ok); break;
              case RV_SECREL:     val -= sec->sh_addr; break;
              case RV_LTREL_FPTR: val = get_ltoff(mod, get_fdesc(mod, val, &ok), &ok); break;

              case RV_PCREL:
                switch (r_type) {
                      case R_IA64_PCREL21B:
                        if ((in_init(mod, val) && in_core(mod, (uint64_t)location)) ||
                            (in_core(mod, val) && in_init(mod, (uint64_t)location))) {
                                /*
                                 * Init section may have been allocated far away from core,
                                 * if the branch won't reach, then allocate a plt for it.
                                 */
                                uint64_t delta = ((int64_t)val - (int64_t)location) / 16;
                                if (delta + (1 << 20) >= (1 << 21)) {
                                        val = get_fdesc(mod, val, &ok);
                                        val = get_plt(mod, location, val, &ok);
                                }
                        } else if (!is_internal(mod, val))
                                val = get_plt(mod, location, val, &ok);
                        /* FALL THROUGH */
                      default:
                        val -= bundle(location);
                        break;

                      case R_IA64_PCREL32MSB:
                      case R_IA64_PCREL32LSB:
                      case R_IA64_PCREL64MSB:
                      case R_IA64_PCREL64LSB:
                        val -= (uint64_t) location;
                        break;

                }
                switch (r_type) {
                      case R_IA64_PCREL60B: format = RF_INSN60; break;
                      case R_IA64_PCREL21B: format = RF_INSN21B; break;
                      case R_IA64_PCREL21M: format = RF_INSN21M; break;
                      case R_IA64_PCREL21F: format = RF_INSN21F; break;
                      default: break;
                }
                break;

              case RV_BDREL:
                val -= (uint64_t) (in_init(mod, val) ? mod->module_init : mod->module_core);
                break;

              case RV_LTV:
                /* can link-time value relocs happen here?  */
                BUG();
                break;

              case RV_PCREL2:
                if (r_type == R_IA64_PCREL21BI) {
                        if (!is_internal(mod, val)) {
                                printk(KERN_ERR "%s: %s reloc against non-local symbol (%lx)\n",
                                       __func__, reloc_name[r_type], val);
                                return -ENOEXEC;
                        }
                        format = RF_INSN21B;
                }
                val -= bundle(location);
                break;

              case RV_SPECIAL:
                switch (r_type) {
                      case R_IA64_IPLTMSB:
                      case R_IA64_IPLTLSB:
                        val = get_fdesc(mod, get_plt(mod, location, val, &ok), &ok);
                        format = RF_64LSB;
                        if (r_type == R_IA64_IPLTMSB)
                                format = RF_64MSB;
                        break;

                      case R_IA64_SUB:
                        val = addend - sym->st_value;
                        format = RF_INSN64;
                        break;

                      case R_IA64_LTOFF22X:
                        if (gp_addressable(mod, val))
                                val -= mod->arch.gp;
                        else
                                val = get_ltoff(mod, val, &ok);
                        format = RF_INSN22;
                        break;

                      case R_IA64_LDXMOV:
                        if (gp_addressable(mod, val)) {
                                /* turn "ld8" into "mov": */
                                DEBUGP("%s: patching ld8 at %p to mov\n", __func__, location);
                                ia64_patch((u64) location, 0x1fff80fe000UL, 0x10000000000UL);
                        }
                        return 0;

                      default:
                        if (reloc_name[r_type])
                                printk(KERN_ERR "%s: special reloc %s not supported",
                                       mod->name, reloc_name[r_type]);
                        else
                                printk(KERN_ERR "%s: unknown special reloc %x\n",
                                       mod->name, r_type);
                        return -ENOEXEC;
                }
                break;

              case RV_TPREL:
              case RV_LTREL_TPREL:
              case RV_DTPMOD:
              case RV_LTREL_DTPMOD:
              case RV_DTPREL:
              case RV_LTREL_DTPREL:
                printk(KERN_ERR "%s: %s reloc not supported\n",
                       mod->name, reloc_name[r_type] ? reloc_name[r_type] : "?");
                return -ENOEXEC;

              default:
                printk(KERN_ERR "%s: unknown reloc %x\n", mod->name, r_type);
                return -ENOEXEC;
        }

        if (!ok)
                return -ENOEXEC;

        DEBUGP("%s: [%p]<-%016lx = %s(%lx)\n", __func__, location, val,
               reloc_name[r_type] ? reloc_name[r_type] : "?", sym->st_value + addend);

        switch (format) {
              case RF_INSN21B:  ok = apply_imm21b(mod, location, (int64_t) val / 16); break;
              case RF_INSN22:   ok = apply_imm22(mod, location, val); break;
              case RF_INSN64:   ok = apply_imm64(mod, location, val); break;
              case RF_INSN60:   ok = apply_imm60(mod, location, (int64_t) val / 16); break;
              case RF_32LSB:    put_unaligned(val, (uint32_t *) location); break;
              case RF_64LSB:    put_unaligned(val, (uint64_t *) location); break;
              case RF_32MSB:    /* ia64 Linux is little-endian... */
              case RF_64MSB:    /* ia64 Linux is little-endian... */
              case RF_INSN14:   /* must be within-module, i.e., resolved by "ld -r" */
              case RF_INSN21M:  /* must be within-module, i.e., resolved by "ld -r" */
              case RF_INSN21F:  /* must be within-module, i.e., resolved by "ld -r" */
                printk(KERN_ERR "%s: format %u needed by %s reloc is not supported\n",
                       mod->name, format, reloc_name[r_type] ? reloc_name[r_type] : "?");
                return -ENOEXEC;

              default:
                printk(KERN_ERR "%s: relocation %s resulted in unknown format %u\n",
                       mod->name, reloc_name[r_type] ? reloc_name[r_type] : "?", format);
                return -ENOEXEC;
        }
        return ok ? 0 : -ENOEXEC;
}

int
apply_relocate_add (Elf64_Shdr *sechdrs, const char *strtab, unsigned int symindex,
                    unsigned int relsec, struct module *mod)
{
        unsigned int i, n = sechdrs[relsec].sh_size / sizeof(Elf64_Rela);
        Elf64_Rela *rela = (void *) sechdrs[relsec].sh_addr;
        Elf64_Shdr *target_sec;
        int ret;

        DEBUGP("%s: applying section %u (%u relocs) to %u\n", __func__,
               relsec, n, sechdrs[relsec].sh_info);

        target_sec = sechdrs + sechdrs[relsec].sh_info;

        if (target_sec->sh_entsize == ~0UL)
                /*
                 * If target section wasn't allocated, we don't need to relocate it.
                 * Happens, e.g., for debug sections.
                 */
                return 0;

        if (!mod->arch.gp) {
                /*
                 * XXX Should have an arch-hook for running this after final section
                 *     addresses have been selected...
                 */
                uint64_t gp;
                if (mod->core_size > MAX_LTOFF)
                        /*
                         * This takes advantage of fact that SHF_ARCH_SMALL gets allocated
                         * at the end of the module.
                         */
                        gp = mod->core_size - MAX_LTOFF / 2;
                else
                        gp = mod->core_size / 2;
                gp = (uint64_t) mod->module_core + ((gp + 7) & -8);
                mod->arch.gp = gp;
                DEBUGP("%s: placing gp at 0x%lx\n", __func__, gp);
        }

        for (i = 0; i < n; i++) {
                ret = do_reloc(mod, ELF64_R_TYPE(rela[i].r_info),
                               ((Elf64_Sym *) sechdrs[symindex].sh_addr
                                + ELF64_R_SYM(rela[i].r_info)),
                               rela[i].r_addend, target_sec,
                               (void *) target_sec->sh_addr + rela[i].r_offset);
                if (ret < 0)
                        return ret;
        }
        return 0;
}

int
apply_relocate (Elf64_Shdr *sechdrs, const char *strtab, unsigned int symindex,
                unsigned int relsec, struct module *mod)
{
        printk(KERN_ERR "module %s: REL relocs in section %u unsupported\n", mod->name, relsec);
        return -ENOEXEC;
}

/*
 * Modules contain a single unwind table which covers both the core and the init text
 * sections but since the two are not contiguous, we need to split this table up such that
 * we can register (and unregister) each "segment" separately.  Fortunately, this sounds
 * more complicated than it really is.
 */
static void
register_unwind_table (struct module *mod)
{
        struct unw_table_entry *start = (void *) mod->arch.unwind->sh_addr;
        struct unw_table_entry *end = start + mod->arch.unwind->sh_size / sizeof (*start);
        struct unw_table_entry tmp, *e1, *e2, *core, *init;
        unsigned long num_init = 0, num_core = 0;

        /* First, count how many init and core unwind-table entries there are.  */
        for (e1 = start; e1 < end; ++e1)
                if (in_init(mod, e1->start_offset))
                        ++num_init;
                else
                        ++num_core;
        /*
         * Second, sort the table such that all unwind-table entries for the init and core
         * text sections are nicely separated.  We do this with a stupid bubble sort
         * (unwind tables don't get ridiculously huge).
         */
        for (e1 = start; e1 < end; ++e1) {
                for (e2 = e1 + 1; e2 < end; ++e2) {
                        if (e2->start_offset < e1->start_offset) {
                                tmp = *e1;
                                *e1 = *e2;
                                *e2 = tmp;
                        }
                }
        }
        /*
         * Third, locate the init and core segments in the unwind table:
         */
        if (in_init(mod, start->start_offset)) {
                init = start;
                core = start + num_init;
        } else {
                core = start;
                init = start + num_core;
        }

        DEBUGP("%s: name=%s, gp=%lx, num_init=%lu, num_core=%lu\n", __func__,
               mod->name, mod->arch.gp, num_init, num_core);

        /*
         * Fourth, register both tables (if not empty).
         */
        if (num_core > 0) {
                mod->arch.core_unw_table = unw_add_unwind_table(mod->name, 0, mod->arch.gp,
                                                                core, core + num_core);
                DEBUGP("%s:  core: handle=%p [%p-%p)\n", __func__,
                       mod->arch.core_unw_table, core, core + num_core);
        }
        if (num_init > 0) {
                mod->arch.init_unw_table = unw_add_unwind_table(mod->name, 0, mod->arch.gp,
                                                                init, init + num_init);
                DEBUGP("%s:  init: handle=%p [%p-%p)\n", __func__,
                       mod->arch.init_unw_table, init, init + num_init);
        }
}

int
module_finalize (const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, struct module *mod)
{
        DEBUGP("%s: init: entry=%p\n", __func__, mod->init);
        if (mod->arch.unwind)
                register_unwind_table(mod);
        return 0;
}

void
module_arch_cleanup (struct module *mod)
{
        if (mod->arch.init_unw_table)
                unw_remove_unwind_table(mod->arch.init_unw_table);
        if (mod->arch.core_unw_table)
                unw_remove_unwind_table(mod->arch.core_unw_table);
}