// SPDX-License-Identifier: GPL-2.0+
/*
 *  Kernel module help for s390.
 *
 *  S390 version
 *    Copyright IBM Corp. 2002, 2003
 *    Author(s): Arnd Bergmann (arndb@de.ibm.com)
 *               Martin Schwidefsky (schwidefsky@de.ibm.com)
 *
 *  based on i386 version
 *    Copyright (C) 2001 Rusty Russell.
 */
#include <linux/module.h>
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/ftrace.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/kasan.h>
#include <linux/moduleloader.h>
#include <linux/bug.h>
#include <linux/memory.h>
#include <linux/execmem.h>
#include <asm/arch-stackprotector.h>
#include <asm/alternative.h>
#include <asm/nospec-branch.h>
#include <asm/facility.h>
#include <asm/ftrace.lds.h>
#include <asm/set_memory.h>
#include <asm/setup.h>
#include <asm/asm-offsets.h>

#if 0
#define DEBUGP printk
#else
#define DEBUGP(fmt , ...)
#endif

#define PLT_ENTRY_SIZE 22

#ifdef CONFIG_FUNCTION_TRACER
void module_arch_cleanup(struct module *mod)
{
        execmem_free(mod->arch.trampolines_start);
}
#endif

void module_arch_freeing_init(struct module *mod)
{
        if (is_livepatch_module(mod) &&
            mod->state == MODULE_STATE_LIVE)
                return;

        vfree(mod->arch.syminfo);
        mod->arch.syminfo = NULL;
}

static void check_rela(Elf_Rela *rela, struct module *me)
{
        struct mod_arch_syminfo *info;

        info = me->arch.syminfo + ELF_R_SYM (rela->r_info);
        switch (ELF_R_TYPE (rela->r_info)) {
        case R_390_GOT12:       /* 12 bit GOT offset.  */
        case R_390_GOT16:       /* 16 bit GOT offset.  */
        case R_390_GOT20:       /* 20 bit GOT offset.  */
        case R_390_GOT32:       /* 32 bit GOT offset.  */
        case R_390_GOT64:       /* 64 bit GOT offset.  */
        case R_390_GOTENT:      /* 32 bit PC rel. to GOT entry shifted by 1. */
        case R_390_GOTPLT12:    /* 12 bit offset to jump slot.  */
        case R_390_GOTPLT16:    /* 16 bit offset to jump slot.  */
        case R_390_GOTPLT20:    /* 20 bit offset to jump slot.  */
        case R_390_GOTPLT32:    /* 32 bit offset to jump slot.  */
        case R_390_GOTPLT64:    /* 64 bit offset to jump slot.  */
        case R_390_GOTPLTENT:   /* 32 bit rel. offset to jump slot >> 1. */
                if (info->got_offset == -1UL) {
                        info->got_offset = me->arch.got_size;
                        me->arch.got_size += sizeof(void*);
                }
                break;
        case R_390_PLT16DBL:    /* 16 bit PC rel. PLT shifted by 1.  */
        case R_390_PLT32DBL:    /* 32 bit PC rel. PLT shifted by 1.  */
        case R_390_PLT32:       /* 32 bit PC relative PLT address.  */
        case R_390_PLT64:       /* 64 bit PC relative PLT address.  */
        case R_390_PLTOFF16:    /* 16 bit offset from GOT to PLT. */
        case R_390_PLTOFF32:    /* 32 bit offset from GOT to PLT. */
        case R_390_PLTOFF64:    /* 16 bit offset from GOT to PLT. */
                if (info->plt_offset == -1UL) {
                        info->plt_offset = me->arch.plt_size;
                        me->arch.plt_size += PLT_ENTRY_SIZE;
                }
                break;
        case R_390_COPY:
        case R_390_GLOB_DAT:
        case R_390_JMP_SLOT:
        case R_390_RELATIVE:
                /* Only needed if we want to support loading of 
                   modules linked with -shared. */
                break;
        }
}

/*
 * Account for GOT and PLT relocations. We can't add sections for
 * got and plt but we can increase the core module size.
 */
int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
                              char *secstrings, struct module *me)
{
        Elf_Shdr *symtab;
        Elf_Sym *symbols;
        Elf_Rela *rela;
        char *strings;
        int nrela, i, j;
        struct module_memory *mod_mem;

        /* Find symbol table and string table. */
        symtab = NULL;
        for (i = 0; i < hdr->e_shnum; i++)
                switch (sechdrs[i].sh_type) {
                case SHT_SYMTAB:
                        symtab = sechdrs + i;
                        break;
                }
        if (!symtab) {
                printk(KERN_ERR "module %s: no symbol table\n", me->name);
                return -ENOEXEC;
        }

        /* Allocate one syminfo structure per symbol. */
        me->arch.nsyms = symtab->sh_size / sizeof(Elf_Sym);
        me->arch.syminfo = vmalloc(array_size(sizeof(struct mod_arch_syminfo),
                                              me->arch.nsyms));
        if (!me->arch.syminfo)
                return -ENOMEM;
        symbols = (void *) hdr + symtab->sh_offset;
        strings = (void *) hdr + sechdrs[symtab->sh_link].sh_offset;
        for (i = 0; i < me->arch.nsyms; i++) {
                if (symbols[i].st_shndx == SHN_UNDEF &&
                    strcmp(strings + symbols[i].st_name,
                           "_GLOBAL_OFFSET_TABLE_") == 0)
                        /* "Define" it as absolute. */
                        symbols[i].st_shndx = SHN_ABS;
                me->arch.syminfo[i].got_offset = -1UL;
                me->arch.syminfo[i].plt_offset = -1UL;
                me->arch.syminfo[i].got_initialized = 0;
                me->arch.syminfo[i].plt_initialized = 0;
        }

        /* Search for got/plt relocations. */
        me->arch.got_size = me->arch.plt_size = 0;
        for (i = 0; i < hdr->e_shnum; i++) {
                if (sechdrs[i].sh_type != SHT_RELA)
                        continue;
                nrela = sechdrs[i].sh_size / sizeof(Elf_Rela);
                rela = (void *) hdr + sechdrs[i].sh_offset;
                for (j = 0; j < nrela; j++)
                        check_rela(rela + j, me);
        }

        /* Increase core size by size of got & plt and set start
           offsets for got and plt. */
        mod_mem = &me->mem[MOD_TEXT];
        mod_mem->size = ALIGN(mod_mem->size, 4);
        me->arch.got_offset = mod_mem->size;
        mod_mem->size += me->arch.got_size;
        me->arch.plt_offset = mod_mem->size;
        if (me->arch.plt_size) {
                if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable)
                        me->arch.plt_size += PLT_ENTRY_SIZE;
                mod_mem->size += me->arch.plt_size;
        }
        return 0;
}

static int apply_rela_bits(Elf_Addr loc, Elf_Addr val,
                           int sign, int bits, int shift,
                           void *(*write)(void *dest, const void *src, size_t len))
{
        unsigned long umax;
        long min, max;
        void *dest = (void *)loc;

        if (val & ((1UL << shift) - 1))
                return -ENOEXEC;
        if (sign) {
                val = (Elf_Addr)(((long) val) >> shift);
                min = -(1L << (bits - 1));
                max = (1L << (bits - 1)) - 1;
                if ((long) val < min || (long) val > max)
                        return -ENOEXEC;
        } else {
                val >>= shift;
                umax = ((1UL << (bits - 1)) << 1) - 1;
                if ((unsigned long) val > umax)
                        return -ENOEXEC;
        }

        if (bits == 8) {
                unsigned char tmp = val;
                write(dest, &tmp, 1);
        } else if (bits == 12) {
                unsigned short tmp = (val & 0xfff) |
                        (*(unsigned short *) loc & 0xf000);
                write(dest, &tmp, 2);
        } else if (bits == 16) {
                unsigned short tmp = val;
                write(dest, &tmp, 2);
        } else if (bits == 20) {
                unsigned int tmp = (val & 0xfff) << 16 |
                        (val & 0xff000) >> 4 | (*(unsigned int *) loc & 0xf00000ff);
                write(dest, &tmp, 4);
        } else if (bits == 32) {
                unsigned int tmp = val;
                write(dest, &tmp, 4);
        } else if (bits == 64) {
                unsigned long tmp = val;
                write(dest, &tmp, 8);
        }
        return 0;
}

static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
                      const char *strtab, struct module *me,
                      void *(*write)(void *dest, const void *src, size_t len))
{
        struct mod_arch_syminfo *info;
        Elf_Addr loc, val;
        int r_type, r_sym;
        int rc = -ENOEXEC;

        /* This is where to make the change */
        loc = base + rela->r_offset;
        /* This is the symbol it is referring to.  Note that all
           undefined symbols have been resolved.  */
        r_sym = ELF_R_SYM(rela->r_info);
        r_type = ELF_R_TYPE(rela->r_info);
        info = me->arch.syminfo + r_sym;
        val = symtab[r_sym].st_value;

        switch (r_type) {
        case R_390_NONE:        /* No relocation.  */
                rc = 0;
                break;
        case R_390_8:           /* Direct 8 bit.   */
        case R_390_12:          /* Direct 12 bit.  */
        case R_390_16:          /* Direct 16 bit.  */
        case R_390_20:          /* Direct 20 bit.  */
        case R_390_32:          /* Direct 32 bit.  */
        case R_390_64:          /* Direct 64 bit.  */
                val += rela->r_addend;
                if (r_type == R_390_8)
                        rc = apply_rela_bits(loc, val, 0, 8, 0, write);
                else if (r_type == R_390_12)
                        rc = apply_rela_bits(loc, val, 0, 12, 0, write);
                else if (r_type == R_390_16)
                        rc = apply_rela_bits(loc, val, 0, 16, 0, write);
                else if (r_type == R_390_20)
                        rc = apply_rela_bits(loc, val, 1, 20, 0, write);
                else if (r_type == R_390_32)
                        rc = apply_rela_bits(loc, val, 0, 32, 0, write);
                else if (r_type == R_390_64)
                        rc = apply_rela_bits(loc, val, 0, 64, 0, write);
                break;
        case R_390_PC16:        /* PC relative 16 bit.  */
        case R_390_PC16DBL:     /* PC relative 16 bit shifted by 1.  */
        case R_390_PC32DBL:     /* PC relative 32 bit shifted by 1.  */
        case R_390_PC32:        /* PC relative 32 bit.  */
        case R_390_PC64:        /* PC relative 64 bit.  */
                val += rela->r_addend - loc;
                if (r_type == R_390_PC16)
                        rc = apply_rela_bits(loc, val, 1, 16, 0, write);
                else if (r_type == R_390_PC16DBL)
                        rc = apply_rela_bits(loc, val, 1, 16, 1, write);
                else if (r_type == R_390_PC32DBL)
                        rc = apply_rela_bits(loc, val, 1, 32, 1, write);
                else if (r_type == R_390_PC32)
                        rc = apply_rela_bits(loc, val, 1, 32, 0, write);
                else if (r_type == R_390_PC64)
                        rc = apply_rela_bits(loc, val, 1, 64, 0, write);
                break;
        case R_390_GOT12:       /* 12 bit GOT offset.  */
        case R_390_GOT16:       /* 16 bit GOT offset.  */
        case R_390_GOT20:       /* 20 bit GOT offset.  */
        case R_390_GOT32:       /* 32 bit GOT offset.  */
        case R_390_GOT64:       /* 64 bit GOT offset.  */
        case R_390_GOTENT:      /* 32 bit PC rel. to GOT entry shifted by 1. */
        case R_390_GOTPLT12:    /* 12 bit offset to jump slot.  */
        case R_390_GOTPLT20:    /* 20 bit offset to jump slot.  */
        case R_390_GOTPLT16:    /* 16 bit offset to jump slot.  */
        case R_390_GOTPLT32:    /* 32 bit offset to jump slot.  */
        case R_390_GOTPLT64:    /* 64 bit offset to jump slot.  */
        case R_390_GOTPLTENT:   /* 32 bit rel. offset to jump slot >> 1. */
                if (info->got_initialized == 0) {
                        Elf_Addr *gotent = me->mem[MOD_TEXT].base +
                                           me->arch.got_offset +
                                           info->got_offset;

                        write(gotent, &val, sizeof(*gotent));
                        info->got_initialized = 1;
                }
                val = info->got_offset + rela->r_addend;
                if (r_type == R_390_GOT12 ||
                    r_type == R_390_GOTPLT12)
                        rc = apply_rela_bits(loc, val, 0, 12, 0, write);
                else if (r_type == R_390_GOT16 ||
                         r_type == R_390_GOTPLT16)
                        rc = apply_rela_bits(loc, val, 0, 16, 0, write);
                else if (r_type == R_390_GOT20 ||
                         r_type == R_390_GOTPLT20)
                        rc = apply_rela_bits(loc, val, 1, 20, 0, write);
                else if (r_type == R_390_GOT32 ||
                         r_type == R_390_GOTPLT32)
                        rc = apply_rela_bits(loc, val, 0, 32, 0, write);
                else if (r_type == R_390_GOT64 ||
                         r_type == R_390_GOTPLT64)
                        rc = apply_rela_bits(loc, val, 0, 64, 0, write);
                else if (r_type == R_390_GOTENT ||
                         r_type == R_390_GOTPLTENT) {
                        val += (Elf_Addr)me->mem[MOD_TEXT].base +
                                me->arch.got_offset - loc;
                        rc = apply_rela_bits(loc, val, 1, 32, 1, write);
                }
                break;
        case R_390_PLT16DBL:    /* 16 bit PC rel. PLT shifted by 1.  */
        case R_390_PLT32DBL:    /* 32 bit PC rel. PLT shifted by 1.  */
        case R_390_PLT32:       /* 32 bit PC relative PLT address.  */
        case R_390_PLT64:       /* 64 bit PC relative PLT address.  */
        case R_390_PLTOFF16:    /* 16 bit offset from GOT to PLT. */
        case R_390_PLTOFF32:    /* 32 bit offset from GOT to PLT. */
        case R_390_PLTOFF64:    /* 16 bit offset from GOT to PLT. */
                if (info->plt_initialized == 0) {
                        unsigned char insn[PLT_ENTRY_SIZE];
                        char *plt_base;
                        char *ip;

                        plt_base = me->mem[MOD_TEXT].base + me->arch.plt_offset;
                        ip = plt_base + info->plt_offset;
                        *(int *)insn = 0x0d10e310;      /* basr 1,0  */
                        *(int *)&insn[4] = 0x100c0004;  /* lg   1,12(1) */
                        if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable) {
                                char *jump_r1;

                                jump_r1 = plt_base + me->arch.plt_size -
                                        PLT_ENTRY_SIZE;
                                /* brcl 0xf,__jump_r1 */
                                *(short *)&insn[8] = 0xc0f4;
                                *(int *)&insn[10] = (jump_r1 - (ip + 8)) / 2;
                        } else {
                                *(int *)&insn[8] = 0x07f10000;  /* br %r1 */
                        }
                        *(long *)&insn[14] = val;

                        write(ip, insn, sizeof(insn));
                        info->plt_initialized = 1;
                }
                if (r_type == R_390_PLTOFF16 ||
                    r_type == R_390_PLTOFF32 ||
                    r_type == R_390_PLTOFF64)
                        val = me->arch.plt_offset - me->arch.got_offset +
                                info->plt_offset + rela->r_addend;
                else {
                        if (!((r_type == R_390_PLT16DBL &&
                               val - loc + 0xffffUL < 0x1ffffeUL) ||
                              (r_type == R_390_PLT32DBL &&
                               val - loc + 0xffffffffULL < 0x1fffffffeULL)))
                                val = (Elf_Addr) me->mem[MOD_TEXT].base +
                                        me->arch.plt_offset +
                                        info->plt_offset;
                        val += rela->r_addend - loc;
                }
                if (r_type == R_390_PLT16DBL)
                        rc = apply_rela_bits(loc, val, 1, 16, 1, write);
                else if (r_type == R_390_PLTOFF16)
                        rc = apply_rela_bits(loc, val, 0, 16, 0, write);
                else if (r_type == R_390_PLT32DBL)
                        rc = apply_rela_bits(loc, val, 1, 32, 1, write);
                else if (r_type == R_390_PLT32 ||
                         r_type == R_390_PLTOFF32)
                        rc = apply_rela_bits(loc, val, 0, 32, 0, write);
                else if (r_type == R_390_PLT64 ||
                         r_type == R_390_PLTOFF64)
                        rc = apply_rela_bits(loc, val, 0, 64, 0, write);
                break;
        case R_390_GOTOFF16:    /* 16 bit offset to GOT.  */
        case R_390_GOTOFF32:    /* 32 bit offset to GOT.  */
        case R_390_GOTOFF64:    /* 64 bit offset to GOT. */
                val = val + rela->r_addend -
                        ((Elf_Addr) me->mem[MOD_TEXT].base + me->arch.got_offset);
                if (r_type == R_390_GOTOFF16)
                        rc = apply_rela_bits(loc, val, 0, 16, 0, write);
                else if (r_type == R_390_GOTOFF32)
                        rc = apply_rela_bits(loc, val, 0, 32, 0, write);
                else if (r_type == R_390_GOTOFF64)
                        rc = apply_rela_bits(loc, val, 0, 64, 0, write);
                break;
        case R_390_GOTPC:       /* 32 bit PC relative offset to GOT. */
        case R_390_GOTPCDBL:    /* 32 bit PC rel. off. to GOT shifted by 1. */
                val = (Elf_Addr) me->mem[MOD_TEXT].base + me->arch.got_offset +
                        rela->r_addend - loc;
                if (r_type == R_390_GOTPC)
                        rc = apply_rela_bits(loc, val, 1, 32, 0, write);
                else if (r_type == R_390_GOTPCDBL)
                        rc = apply_rela_bits(loc, val, 1, 32, 1, write);
                break;
        case R_390_COPY:
        case R_390_GLOB_DAT:    /* Create GOT entry.  */
        case R_390_JMP_SLOT:    /* Create PLT entry.  */
        case R_390_RELATIVE:    /* Adjust by program base.  */
                /* Only needed if we want to support loading of 
                   modules linked with -shared. */
                return -ENOEXEC;
        default:
                printk(KERN_ERR "module %s: unknown relocation: %u\n",
                       me->name, r_type);
                return -ENOEXEC;
        }
        if (rc) {
                printk(KERN_ERR "module %s: relocation error for symbol %s "
                       "(r_type %i, value 0x%lx)\n",
                       me->name, strtab + symtab[r_sym].st_name,
                       r_type, (unsigned long) val);
                return rc;
        }
        return 0;
}

static int __apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
                       unsigned int symindex, unsigned int relsec,
                       struct module *me,
                       void *(*write)(void *dest, const void *src, size_t len))
{
        Elf_Addr base;
        Elf_Sym *symtab;
        Elf_Rela *rela;
        unsigned long i, n;
        int rc;

        DEBUGP("Applying relocate section %u to %u\n",
               relsec, sechdrs[relsec].sh_info);
        base = sechdrs[sechdrs[relsec].sh_info].sh_addr;
        symtab = (Elf_Sym *) sechdrs[symindex].sh_addr;
        rela = (Elf_Rela *) sechdrs[relsec].sh_addr;
        n = sechdrs[relsec].sh_size / sizeof(Elf_Rela);

        for (i = 0; i < n; i++, rela++) {
                rc = apply_rela(rela, base, symtab, strtab, me, write);
                if (rc)
                        return rc;
        }
        return 0;
}

int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
                       unsigned int symindex, unsigned int relsec,
                       struct module *me)
{
        bool early = me->state == MODULE_STATE_UNFORMED;
        void *(*write)(void *, const void *, size_t) = memcpy;

        if (!early)
                write = s390_kernel_write;

        return __apply_relocate_add(sechdrs, strtab, symindex, relsec, me,
                                    write);
}

#ifdef CONFIG_FUNCTION_TRACER
static int module_alloc_ftrace_hotpatch_trampolines(struct module *me,
                                                    const Elf_Shdr *s)
{
        char *start, *end;
        int numpages;
        size_t size;

        size = FTRACE_HOTPATCH_TRAMPOLINES_SIZE(s->sh_size);
        numpages = DIV_ROUND_UP(size, PAGE_SIZE);
        start = execmem_alloc(EXECMEM_FTRACE, numpages * PAGE_SIZE);
        if (!start)
                return -ENOMEM;
        set_memory_rox((unsigned long)start, numpages);
        end = start + size;

        me->arch.trampolines_start = (struct ftrace_hotpatch_trampoline *)start;
        me->arch.trampolines_end = (struct ftrace_hotpatch_trampoline *)end;
        me->arch.next_trampoline = me->arch.trampolines_start;

        return 0;
}
#endif /* CONFIG_FUNCTION_TRACER */

int module_finalize(const Elf_Ehdr *hdr,
                    const Elf_Shdr *sechdrs,
                    struct module *me)
{
        const Elf_Shdr *s;
        char *secstrings, *secname;
        void *aseg;
        int rc = 0;

        if (IS_ENABLED(CONFIG_EXPOLINE) &&
            !nospec_disable && me->arch.plt_size) {
                unsigned int *ij;

                ij = me->mem[MOD_TEXT].base + me->arch.plt_offset +
                        me->arch.plt_size - PLT_ENTRY_SIZE;
                ij[0] = 0xc6000000;     /* exrl %r0,.+10        */
                ij[1] = 0x0005a7f4;     /* j    .               */
                ij[2] = 0x000007f1;     /* br   %r1             */
        }

        secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
        for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
                aseg = (void *) s->sh_addr;
                secname = secstrings + s->sh_name;

                if (!strcmp(".altinstructions", secname))
                        /* patch .altinstructions */
                        apply_alternatives(aseg, aseg + s->sh_size);

                if (IS_ENABLED(CONFIG_EXPOLINE) &&
                    (str_has_prefix(secname, ".s390_indirect")))
                        nospec_revert(aseg, aseg + s->sh_size);

                if (IS_ENABLED(CONFIG_EXPOLINE) &&
                    (str_has_prefix(secname, ".s390_return")))
                        nospec_revert(aseg, aseg + s->sh_size);

                if (IS_ENABLED(CONFIG_STACKPROTECTOR) &&
                    (str_has_prefix(secname, "__stack_protector_loc"))) {
                        rc = stack_protector_apply(aseg, aseg + s->sh_size);
                        if (rc)
                                break;
                }

#ifdef CONFIG_FUNCTION_TRACER
                if (!strcmp(FTRACE_CALLSITE_SECTION, secname)) {
                        rc = module_alloc_ftrace_hotpatch_trampolines(me, s);
                        if (rc)
                                break;
                }
#endif /* CONFIG_FUNCTION_TRACER */
        }

        return rc;
}