/*
 * Copyright 2010 Tilera Corporation. All Rights Reserved.
 *
 *   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, version 2.
 *
 *   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, GOOD TITLE or
 *   NON INFRINGEMENT.  See the GNU General Public License for
 *   more details.
 *
 * Based on i386 version, copyright (C) 2001 Rusty Russell.
 */

#include <linux/moduleloader.h>
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <asm/pgtable.h>
#include <asm/homecache.h>
#include <arch/opcode.h>

#ifdef MODULE_DEBUG
#define DEBUGP printk
#else
#define DEBUGP(fmt...)
#endif

/*
 * Allocate some address space in the range MEM_MODULE_START to
 * MEM_MODULE_END and populate it with memory.
 */
void *module_alloc(unsigned long size)
{
        struct page **pages;
        pgprot_t prot_rwx = __pgprot(_PAGE_KERNEL | _PAGE_KERNEL_EXEC);
        struct vm_struct *area;
        int i = 0;
        int npages;

        npages = (size + PAGE_SIZE - 1) / PAGE_SIZE;
        pages = kmalloc(npages * sizeof(struct page *), GFP_KERNEL);
        if (pages == NULL)
                return NULL;
        for (; i < npages; ++i) {
                pages[i] = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
                if (!pages[i])
                        goto error;
        }

        area = __get_vm_area(size, VM_ALLOC, MEM_MODULE_START, MEM_MODULE_END);
        if (!area)
                goto error;
        area->nr_pages = npages;
        area->pages = pages;

        if (map_vm_area(area, prot_rwx, pages)) {
                vunmap(area->addr);
                goto error;
        }

        return area->addr;

error:
        while (--i >= 0)
                __free_page(pages[i]);
        kfree(pages);
        return NULL;
}


/* Free memory returned from module_alloc */
void module_memfree(void *module_region)
{
        vfree(module_region);

        /* Globally flush the L1 icache. */
        flush_remote(0, HV_FLUSH_EVICT_L1I, cpu_online_mask,
                     0, 0, 0, NULL, NULL, 0);

        /*
         * FIXME: Add module_arch_freeing_init to trim exception
         * table entries.
         */
}

#ifdef __tilegx__
/*
 * Validate that the high 16 bits of "value" is just the sign-extension of
 * the low 48 bits.
 */
static int validate_hw2_last(long value, struct module *me)
{
        if (((value << 16) >> 16) != value) {
                pr_warn("module %s: Out of range HW2_LAST value %#lx\n",
                        me->name, value);
                return 0;
        }
        return 1;
}

/*
 * Validate that "value" isn't too big to hold in a JumpOff relocation.
 */
static int validate_jumpoff(long value)
{
        /* Determine size of jump offset. */
        int shift = __builtin_clzl(get_JumpOff_X1(create_JumpOff_X1(-1)));

        /* Check to see if it fits into the relocation slot. */
        long f = get_JumpOff_X1(create_JumpOff_X1(value));
        f = (f << shift) >> shift;

        return f == value;
}
#endif

int apply_relocate_add(Elf_Shdr *sechdrs,
                       const char *strtab,
                       unsigned int symindex,
                       unsigned int relsec,
                       struct module *me)
{
        unsigned int i;
        Elf_Rela *rel = (void *)sechdrs[relsec].sh_addr;
        Elf_Sym *sym;
        u64 *location;
        unsigned long value;

        DEBUGP("Applying relocate section %u to %u\n", relsec,
               sechdrs[relsec].sh_info);
        for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
                /* This is where to make the change */
                location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
                        + rel[i].r_offset;
                /*
                 * This is the symbol it is referring to.
                 * Note that all undefined symbols have been resolved.
                 */
                sym = (Elf_Sym *)sechdrs[symindex].sh_addr
                        + ELF_R_SYM(rel[i].r_info);
                value = sym->st_value + rel[i].r_addend;

                switch (ELF_R_TYPE(rel[i].r_info)) {

#ifdef __LITTLE_ENDIAN
# define MUNGE(func) \
        (*location = ((*location & ~func(-1)) | func(value)))
#else
/*
 * Instructions are always little-endian, so when we read them as data,
 * we have to swap them around before and after modifying them.
 */
# define MUNGE(func) \
        (*location = swab64((swab64(*location) & ~func(-1)) | func(value)))
#endif

#ifndef __tilegx__
                case R_TILE_32:
                        *(uint32_t *)location = value;
                        break;
                case R_TILE_IMM16_X0_HA:
                        value = (value + 0x8000) >> 16;
                        /*FALLTHROUGH*/
                case R_TILE_IMM16_X0_LO:
                        MUNGE(create_Imm16_X0);
                        break;
                case R_TILE_IMM16_X1_HA:
                        value = (value + 0x8000) >> 16;
                        /*FALLTHROUGH*/
                case R_TILE_IMM16_X1_LO:
                        MUNGE(create_Imm16_X1);
                        break;
                case R_TILE_JOFFLONG_X1:
                        value -= (unsigned long) location;  /* pc-relative */
                        value = (long) value >> 3;     /* count by instrs */
                        MUNGE(create_JOffLong_X1);
                        break;
#else
                case R_TILEGX_64:
                        *location = value;
                        break;
                case R_TILEGX_IMM16_X0_HW2_LAST:
                        if (!validate_hw2_last(value, me))
                                return -ENOEXEC;
                        value >>= 16;
                        /*FALLTHROUGH*/
                case R_TILEGX_IMM16_X0_HW1:
                        value >>= 16;
                        /*FALLTHROUGH*/
                case R_TILEGX_IMM16_X0_HW0:
                        MUNGE(create_Imm16_X0);
                        break;
                case R_TILEGX_IMM16_X1_HW2_LAST:
                        if (!validate_hw2_last(value, me))
                                return -ENOEXEC;
                        value >>= 16;
                        /*FALLTHROUGH*/
                case R_TILEGX_IMM16_X1_HW1:
                        value >>= 16;
                        /*FALLTHROUGH*/
                case R_TILEGX_IMM16_X1_HW0:
                        MUNGE(create_Imm16_X1);
                        break;
                case R_TILEGX_JUMPOFF_X1:
                        value -= (unsigned long) location;  /* pc-relative */
                        value = (long) value >> 3;     /* count by instrs */
                        if (!validate_jumpoff(value)) {
                                pr_warn("module %s: Out of range jump to %#llx at %#llx (%p)\n",
                                        me->name,
                                        sym->st_value + rel[i].r_addend,
                                        rel[i].r_offset, location);
                                return -ENOEXEC;
                        }
                        MUNGE(create_JumpOff_X1);
                        break;
#endif

#undef MUNGE

                default:
                        pr_err("module %s: Unknown relocation: %d\n",
                               me->name, (int) ELF_R_TYPE(rel[i].r_info));
                        return -ENOEXEC;
                }
        }
        return 0;
}