// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
 */

#include <linux/module.h>
#include <linux/moduleloader.h>
#include <linux/kernel.h>
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <asm/unwind.h>

static inline void arc_write_me(unsigned short *addr, unsigned long value)
{
        *addr = (value & 0xffff0000) >> 16;
        *(addr + 1) = (value & 0xffff);
}

/*
 * This gets called before relocation loop in generic loader
 * Make a note of the section index of unwinding section
 */
int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
                              char *secstr, struct module *mod)
{
#ifdef CONFIG_ARC_DW2_UNWIND
        mod->arch.unw_sec_idx = 0;
        mod->arch.unw_info = NULL;
#endif
        mod->arch.secstr = secstr;
        return 0;
}

void module_arch_cleanup(struct module *mod)
{
#ifdef CONFIG_ARC_DW2_UNWIND
        if (mod->arch.unw_info)
                unwind_remove_table(mod->arch.unw_info, 0);
#endif
}

int apply_relocate_add(Elf32_Shdr *sechdrs,
                       const char *strtab,
                       unsigned int symindex,   /* sec index for sym tbl */
                       unsigned int relsec,     /* sec index for relo sec */
                       struct module *module)
{
        int i, n, relo_type;
        Elf32_Rela *rel_entry = (void *)sechdrs[relsec].sh_addr;
        Elf32_Sym *sym_entry, *sym_sec;
        Elf32_Addr relocation, location, tgt_addr;
        unsigned int tgtsec;

        /*
         * @relsec has relocations e.g. .rela.init.text
         * @tgtsec is section to patch e.g. .init.text
         */
        tgtsec = sechdrs[relsec].sh_info;
        tgt_addr = sechdrs[tgtsec].sh_addr;
        sym_sec = (Elf32_Sym *) sechdrs[symindex].sh_addr;
        n = sechdrs[relsec].sh_size / sizeof(*rel_entry);

        pr_debug("\nSection to fixup %s @%x\n",
                 module->arch.secstr + sechdrs[tgtsec].sh_name, tgt_addr);
        pr_debug("=========================================================\n");
        pr_debug("r_off\tr_add\tst_value ADDRESS  VALUE\n");
        pr_debug("=========================================================\n");

        /* Loop thru entries in relocation section */
        for (i = 0; i < n; i++) {
                const char *s;

                /* This is where to make the change */
                location = tgt_addr + rel_entry[i].r_offset;

                /* This is the symbol it is referring to.  Note that all
                   undefined symbols have been resolved.  */
                sym_entry = sym_sec + ELF32_R_SYM(rel_entry[i].r_info);

                relocation = sym_entry->st_value + rel_entry[i].r_addend;

                if (sym_entry->st_name == 0 && ELF_ST_TYPE (sym_entry->st_info) == STT_SECTION) {
                        s = module->arch.secstr + sechdrs[sym_entry->st_shndx].sh_name;
                } else {
                        s = strtab + sym_entry->st_name;
                }

                pr_debug("   %x\t%x\t%x %x %x [%s]\n",
                         rel_entry[i].r_offset, rel_entry[i].r_addend,
                         sym_entry->st_value, location, relocation, s);

                /* This assumes modules are built with -mlong-calls
                 * so any branches/jumps are absolute 32 bit jmps
                 * global data access again is abs 32 bit.
                 * Both of these are handled by same relocation type
                 */
                relo_type = ELF32_R_TYPE(rel_entry[i].r_info);

                if (likely(R_ARC_32_ME == relo_type))   /* ME ( S + A ) */
                        arc_write_me((unsigned short *)location, relocation);
                else if (R_ARC_32 == relo_type)         /* ( S + A ) */
                        *((Elf32_Addr *) location) = relocation;
                else if (R_ARC_32_PCREL == relo_type)   /* ( S + A ) - PDATA ) */
                        *((Elf32_Addr *) location) = relocation - location;
                else
                        goto relo_err;

        }

#ifdef CONFIG_ARC_DW2_UNWIND
        if (strcmp(module->arch.secstr+sechdrs[tgtsec].sh_name, ".eh_frame") == 0)
                module->arch.unw_sec_idx = tgtsec;
#endif

        return 0;

relo_err:
        pr_err("%s: unknown relocation: %u\n",
                module->name, ELF32_R_TYPE(rel_entry[i].r_info));
        return -ENOEXEC;

}

/* Just before lift off: After sections have been relocated, we add the
 * dwarf section to unwinder table pool
 * This couldn't be done in module_frob_arch_sections() because
 * relocations had not been applied by then
 */
int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
                    struct module *mod)
{
#ifdef CONFIG_ARC_DW2_UNWIND
        void *unw;
        int unwsec = mod->arch.unw_sec_idx;

        if (unwsec) {
                unw = unwind_add_table(mod, (void *)sechdrs[unwsec].sh_addr,
                                       sechdrs[unwsec].sh_size);
                mod->arch.unw_info = unw;
        }
#endif
        return 0;
}