// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/arch/arm/kernel/module.c
 *
 *  Copyright (C) 2002 Russell King.
 *  Modified for nommu by Hyok S. Choi
 *
 * Module allocation method suggested by Andi Kleen.
 */
#include <linux/module.h>
#include <linux/moduleloader.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/elf.h>
#include <linux/fs.h>
#include <linux/string.h>

#include <asm/sections.h>
#include <asm/smp_plat.h>
#include <asm/unwind.h>
#include <asm/opcodes.h>

bool module_init_section(const char *name)
{
        return strstarts(name, ".init") ||
                strstarts(name, ".ARM.extab.init") ||
                strstarts(name, ".ARM.exidx.init");
}

bool module_exit_section(const char *name)
{
        return strstarts(name, ".exit") ||
                strstarts(name, ".ARM.extab.exit") ||
                strstarts(name, ".ARM.exidx.exit");
}

#ifdef CONFIG_ARM_HAS_GROUP_RELOCS
/*
 * This implements the partitioning algorithm for group relocations as
 * documented in the ARM AArch32 ELF psABI (IHI 0044).
 *
 * A single PC-relative symbol reference is divided in up to 3 add or subtract
 * operations, where the final one could be incorporated into a load/store
 * instruction with immediate offset. E.g.,
 *
 *   ADD        Rd, PC, #...            or      ADD     Rd, PC, #...
 *   ADD        Rd, Rd, #...                    ADD     Rd, Rd, #...
 *   LDR        Rd, [Rd, #...]                  ADD     Rd, Rd, #...
 *
 * The latter has a guaranteed range of only 16 MiB (3x8 == 24 bits), so it is
 * of limited use in the kernel. However, the ADD/ADD/LDR combo has a range of
 * -/+ 256 MiB, (2x8 + 12 == 28 bits), which means it has sufficient range for
 * any in-kernel symbol reference (unless module PLTs are being used).
 *
 * The main advantage of this approach over the typical pattern using a literal
 * load is that literal loads may miss in the D-cache, and generally lead to
 * lower cache efficiency for variables that are referenced often from many
 * different places in the code.
 */
static u32 get_group_rem(u32 group, u32 *offset)
{
        u32 val = *offset;
        u32 shift;
        do {
                shift = val ? (31 - __fls(val)) & ~1 : 32;
                *offset = val;
                if (!val)
                        break;
                val &= 0xffffff >> shift;
        } while (group--);
        return shift;
}
#endif

int
apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
               unsigned int relindex, struct module *module)
{
        Elf32_Shdr *symsec = sechdrs + symindex;
        Elf32_Shdr *relsec = sechdrs + relindex;
        Elf32_Shdr *dstsec = sechdrs + relsec->sh_info;
        Elf32_Rel *rel = (void *)relsec->sh_addr;
        unsigned int i;

        for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++, rel++) {
                unsigned long loc;
                Elf32_Sym *sym;
                const char *symname;
#ifdef CONFIG_ARM_HAS_GROUP_RELOCS
                u32 shift, group = 1;
#endif
                s32 offset;
                u32 tmp;
#ifdef CONFIG_THUMB2_KERNEL
                u32 upper, lower, sign, j1, j2;
#endif

                offset = ELF32_R_SYM(rel->r_info);
                if (offset < 0 || offset > (symsec->sh_size / sizeof(Elf32_Sym))) {
                        pr_err("%s: section %u reloc %u: bad relocation sym offset\n",
                                module->name, relindex, i);
                        return -ENOEXEC;
                }

                sym = ((Elf32_Sym *)symsec->sh_addr) + offset;
                symname = strtab + sym->st_name;

                if (rel->r_offset < 0 || rel->r_offset > dstsec->sh_size - sizeof(u32)) {
                        pr_err("%s: section %u reloc %u sym '%s': out of bounds relocation, offset %d size %u\n",
                               module->name, relindex, i, symname,
                               rel->r_offset, dstsec->sh_size);
                        return -ENOEXEC;
                }

                loc = dstsec->sh_addr + rel->r_offset;

                switch (ELF32_R_TYPE(rel->r_info)) {
                case R_ARM_NONE:
                        /* ignore */
                        break;

                case R_ARM_ABS32:
                case R_ARM_TARGET1:
                        *(u32 *)loc += sym->st_value;
                        break;

                case R_ARM_PC24:
                case R_ARM_CALL:
                case R_ARM_JUMP24:
                        if (sym->st_value & 3) {
                                pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (ARM -> Thumb)\n",
                                       module->name, relindex, i, symname);
                                return -ENOEXEC;
                        }

                        offset = __mem_to_opcode_arm(*(u32 *)loc);
                        offset = (offset & 0x00ffffff) << 2;
                        offset = sign_extend32(offset, 25);

                        offset += sym->st_value - loc;

                        /*
                         * Route through a PLT entry if 'offset' exceeds the
                         * supported range. Note that 'offset + loc + 8'
                         * contains the absolute jump target, i.e.,
                         * @sym + addend, corrected for the +8 PC bias.
                         */
                        if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) &&
                            (offset <= (s32)0xfe000000 ||
                             offset >= (s32)0x02000000))
                                offset = get_module_plt(module, loc,
                                                        offset + loc + 8)
                                         - loc - 8;

                        if (offset <= (s32)0xfe000000 ||
                            offset >= (s32)0x02000000) {
                                pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
                                       module->name, relindex, i, symname,
                                       ELF32_R_TYPE(rel->r_info), loc,
                                       sym->st_value);
                                return -ENOEXEC;
                        }

                        offset >>= 2;
                        offset &= 0x00ffffff;

                        *(u32 *)loc &= __opcode_to_mem_arm(0xff000000);
                        *(u32 *)loc |= __opcode_to_mem_arm(offset);
                        break;

               case R_ARM_V4BX:
                       /* Preserve Rm and the condition code. Alter
                        * other bits to re-code instruction as
                        * MOV PC,Rm.
                        */
                       *(u32 *)loc &= __opcode_to_mem_arm(0xf000000f);
                       *(u32 *)loc |= __opcode_to_mem_arm(0x01a0f000);
                       break;

                case R_ARM_PREL31:
                        offset = (*(s32 *)loc << 1) >> 1; /* sign extend */
                        offset += sym->st_value - loc;
                        if (offset >= 0x40000000 || offset < -0x40000000) {
                                pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
                                       module->name, relindex, i, symname,
                                       ELF32_R_TYPE(rel->r_info), loc,
                                       sym->st_value);
                                return -ENOEXEC;
                        }
                        *(u32 *)loc &= 0x80000000;
                        *(u32 *)loc |= offset & 0x7fffffff;
                        break;

                case R_ARM_REL32:
                        *(u32 *)loc += sym->st_value - loc;
                        break;

                case R_ARM_MOVW_ABS_NC:
                case R_ARM_MOVT_ABS:
                case R_ARM_MOVW_PREL_NC:
                case R_ARM_MOVT_PREL:
                        offset = tmp = __mem_to_opcode_arm(*(u32 *)loc);
                        offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
                        offset = sign_extend32(offset, 15);

                        offset += sym->st_value;
                        if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_PREL ||
                            ELF32_R_TYPE(rel->r_info) == R_ARM_MOVW_PREL_NC)
                                offset -= loc;
                        if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS ||
                            ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_PREL)
                                offset >>= 16;

                        tmp &= 0xfff0f000;
                        tmp |= ((offset & 0xf000) << 4) |
                                (offset & 0x0fff);

                        *(u32 *)loc = __opcode_to_mem_arm(tmp);
                        break;

#ifdef CONFIG_ARM_HAS_GROUP_RELOCS
                case R_ARM_ALU_PC_G0_NC:
                        group = 0;
                        fallthrough;
                case R_ARM_ALU_PC_G1_NC:
                        tmp = __mem_to_opcode_arm(*(u32 *)loc);
                        offset = ror32(tmp & 0xff, (tmp & 0xf00) >> 7);
                        if (tmp & BIT(22))
                                offset = -offset;
                        offset += sym->st_value - loc;
                        if (offset < 0) {
                                offset = -offset;
                                tmp = (tmp & ~BIT(23)) | BIT(22); // SUB opcode
                        } else {
                                tmp = (tmp & ~BIT(22)) | BIT(23); // ADD opcode
                        }

                        shift = get_group_rem(group, &offset);
                        if (shift < 24) {
                                offset >>= 24 - shift;
                                offset |= (shift + 8) << 7;
                        }
                        *(u32 *)loc = __opcode_to_mem_arm((tmp & ~0xfff) | offset);
                        break;

                case R_ARM_LDR_PC_G2:
                        tmp = __mem_to_opcode_arm(*(u32 *)loc);
                        offset = tmp & 0xfff;
                        if (~tmp & BIT(23))             // U bit cleared?
                                offset = -offset;
                        offset += sym->st_value - loc;
                        if (offset < 0) {
                                offset = -offset;
                                tmp &= ~BIT(23);        // clear U bit
                        } else {
                                tmp |= BIT(23);         // set U bit
                        }
                        get_group_rem(2, &offset);

                        if (offset > 0xfff) {
                                pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
                                       module->name, relindex, i, symname,
                                       ELF32_R_TYPE(rel->r_info), loc,
                                       sym->st_value);
                                return -ENOEXEC;
                        }
                        *(u32 *)loc = __opcode_to_mem_arm((tmp & ~0xfff) | offset);
                        break;
#endif
#ifdef CONFIG_THUMB2_KERNEL
                case R_ARM_THM_CALL:
                case R_ARM_THM_JUMP24:
                        /*
                         * For function symbols, only Thumb addresses are
                         * allowed (no interworking).
                         *
                         * For non-function symbols, the destination
                         * has no specific ARM/Thumb disposition, so
                         * the branch is resolved under the assumption
                         * that interworking is not required.
                         */
                        if (ELF32_ST_TYPE(sym->st_info) == STT_FUNC &&
                            !(sym->st_value & 1)) {
                                pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (Thumb -> ARM)\n",
                                       module->name, relindex, i, symname);
                                return -ENOEXEC;
                        }

                        upper = __mem_to_opcode_thumb16(*(u16 *)loc);
                        lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));

                        /*
                         * 25 bit signed address range (Thumb-2 BL and B.W
                         * instructions):
                         *   S:I1:I2:imm10:imm11:0
                         * where:
                         *   S     = upper[10]   = offset[24]
                         *   I1    = ~(J1 ^ S)   = offset[23]
                         *   I2    = ~(J2 ^ S)   = offset[22]
                         *   imm10 = upper[9:0]  = offset[21:12]
                         *   imm11 = lower[10:0] = offset[11:1]
                         *   J1    = lower[13]
                         *   J2    = lower[11]
                         */
                        sign = (upper >> 10) & 1;
                        j1 = (lower >> 13) & 1;
                        j2 = (lower >> 11) & 1;
                        offset = (sign << 24) | ((~(j1 ^ sign) & 1) << 23) |
                                ((~(j2 ^ sign) & 1) << 22) |
                                ((upper & 0x03ff) << 12) |
                                ((lower & 0x07ff) << 1);
                        offset = sign_extend32(offset, 24);
                        offset += sym->st_value - loc;

                        /*
                         * Route through a PLT entry if 'offset' exceeds the
                         * supported range.
                         */
                        if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) &&
                            (offset <= (s32)0xff000000 ||
                             offset >= (s32)0x01000000))
                                offset = get_module_plt(module, loc,
                                                        offset + loc + 4)
                                         - loc - 4;

                        if (offset <= (s32)0xff000000 ||
                            offset >= (s32)0x01000000) {
                                pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
                                       module->name, relindex, i, symname,
                                       ELF32_R_TYPE(rel->r_info), loc,
                                       sym->st_value);
                                return -ENOEXEC;
                        }

                        sign = (offset >> 24) & 1;
                        j1 = sign ^ (~(offset >> 23) & 1);
                        j2 = sign ^ (~(offset >> 22) & 1);
                        upper = (u16)((upper & 0xf800) | (sign << 10) |
                                            ((offset >> 12) & 0x03ff));
                        lower = (u16)((lower & 0xd000) |
                                      (j1 << 13) | (j2 << 11) |
                                      ((offset >> 1) & 0x07ff));

                        *(u16 *)loc = __opcode_to_mem_thumb16(upper);
                        *(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
                        break;

                case R_ARM_THM_MOVW_ABS_NC:
                case R_ARM_THM_MOVT_ABS:
                case R_ARM_THM_MOVW_PREL_NC:
                case R_ARM_THM_MOVT_PREL:
                        upper = __mem_to_opcode_thumb16(*(u16 *)loc);
                        lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));

                        /*
                         * MOVT/MOVW instructions encoding in Thumb-2:
                         *
                         * i    = upper[10]
                         * imm4 = upper[3:0]
                         * imm3 = lower[14:12]
                         * imm8 = lower[7:0]
                         *
                         * imm16 = imm4:i:imm3:imm8
                         */
                        offset = ((upper & 0x000f) << 12) |
                                ((upper & 0x0400) << 1) |
                                ((lower & 0x7000) >> 4) | (lower & 0x00ff);
                        offset = sign_extend32(offset, 15);
                        offset += sym->st_value;

                        if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_PREL ||
                            ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVW_PREL_NC)
                                offset -= loc;
                        if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS ||
                            ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_PREL)
                                offset >>= 16;

                        upper = (u16)((upper & 0xfbf0) |
                                      ((offset & 0xf000) >> 12) |
                                      ((offset & 0x0800) >> 1));
                        lower = (u16)((lower & 0x8f00) |
                                      ((offset & 0x0700) << 4) |
                                      (offset & 0x00ff));
                        *(u16 *)loc = __opcode_to_mem_thumb16(upper);
                        *(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
                        break;
#endif

                default:
                        pr_err("%s: unknown relocation: %u\n",
                               module->name, ELF32_R_TYPE(rel->r_info));
                        return -ENOEXEC;
                }
        }
        return 0;
}

static const Elf_Shdr *find_mod_section(const Elf32_Ehdr *hdr,
        const Elf_Shdr *sechdrs, const char *name)
{
        const Elf_Shdr *s, *se;
        const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;

        for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++)
                if (strcmp(name, secstrs + s->sh_name) == 0)
                        return s;

        return NULL;
}

extern void fixup_pv_table(const void *, unsigned long);
extern void fixup_smp(const void *, unsigned long);

int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
                    struct module *mod)
{
        const Elf_Shdr *s = NULL;
#ifdef CONFIG_ARM_UNWIND
        const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
        const Elf_Shdr *sechdrs_end = sechdrs + hdr->e_shnum;
        struct list_head *unwind_list = &mod->arch.unwind_list;

        INIT_LIST_HEAD(unwind_list);
        mod->arch.init_table = NULL;

        for (s = sechdrs; s < sechdrs_end; s++) {
                const char *secname = secstrs + s->sh_name;
                const char *txtname;
                const Elf_Shdr *txt_sec;

                if (!(s->sh_flags & SHF_ALLOC) ||
                    s->sh_type != ELF_SECTION_UNWIND)
                        continue;

                if (!strcmp(".ARM.exidx", secname))
                        txtname = ".text";
                else
                        txtname = secname + strlen(".ARM.exidx");
                txt_sec = find_mod_section(hdr, sechdrs, txtname);

                if (txt_sec) {
                        struct unwind_table *table =
                                unwind_table_add(s->sh_addr,
                                                s->sh_size,
                                                txt_sec->sh_addr,
                                                txt_sec->sh_size);

                        list_add(&table->mod_list, unwind_list);

                        /* save init table for module_arch_freeing_init */
                        if (strcmp(".ARM.exidx.init.text", secname) == 0)
                                mod->arch.init_table = table;
                }
        }
#endif
#ifdef CONFIG_ARM_PATCH_PHYS_VIRT
        s = find_mod_section(hdr, sechdrs, ".pv_table");
        if (s)
                fixup_pv_table((void *)s->sh_addr, s->sh_size);
#endif
        s = find_mod_section(hdr, sechdrs, ".alt.smp.init");
        if (s && !is_smp())
#ifdef CONFIG_SMP_ON_UP
                fixup_smp((void *)s->sh_addr, s->sh_size);
#else
                return -EINVAL;
#endif
        return 0;
}

void
module_arch_cleanup(struct module *mod)
{
#ifdef CONFIG_ARM_UNWIND
        struct unwind_table *tmp;
        struct unwind_table *n;

        list_for_each_entry_safe(tmp, n,
                        &mod->arch.unwind_list, mod_list) {
                list_del(&tmp->mod_list);
                unwind_table_del(tmp);
        }
        mod->arch.init_table = NULL;
#endif
}

void module_arch_freeing_init(struct module *mod)
{
#ifdef CONFIG_ARM_UNWIND
        struct unwind_table *init = mod->arch.init_table;

        if (init) {
                mod->arch.init_table = NULL;
                list_del(&init->mod_list);
                unwind_table_del(init);
        }
#endif
}