// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.

#include <linux/moduleloader.h>
#include <linux/elf.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/spinlock.h>

#ifdef CONFIG_CPU_CK810
#define IS_BSR32(hi16, lo16)            (((hi16) & 0xFC00) == 0xE000)
#define IS_JSRI32(hi16, lo16)           ((hi16) == 0xEAE0)

#define CHANGE_JSRI_TO_LRW(addr) do {                                   \
        *(uint16_t *)(addr) = (*(uint16_t *)(addr) & 0xFF9F) | 0x001a;  \
        *((uint16_t *)(addr) + 1) = *((uint16_t *)(addr) + 1) & 0xFFFF; \
} while (0)

#define SET_JSR32_R26(addr) do {                \
        *(uint16_t *)(addr) = 0xE8Fa;           \
        *((uint16_t *)(addr) + 1) = 0x0000;     \
} while (0)

static void jsri_2_lrw_jsr(uint32_t *location)
{
        uint16_t *location_tmp = (uint16_t *)location;

        if (IS_BSR32(*location_tmp, *(location_tmp + 1)))
                return;

        if (IS_JSRI32(*location_tmp, *(location_tmp + 1))) {
                /* jsri 0x...  --> lrw r26, 0x... */
                CHANGE_JSRI_TO_LRW(location);
                /* lsli r0, r0 --> jsr r26 */
                SET_JSR32_R26(location + 1);
        }
}
#else
static inline void jsri_2_lrw_jsr(uint32_t *location)
{
        return;
}
#endif

int apply_relocate_add(Elf32_Shdr *sechdrs, const char *strtab,
                unsigned int symindex, unsigned int relsec, struct module *me)
{
        unsigned int i;
        Elf32_Rela      *rel = (void *) sechdrs[relsec].sh_addr;
        Elf32_Sym       *sym;
        uint32_t        *location;
        short           *temp;

        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;
                sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
                                                + ELF32_R_SYM(rel[i].r_info);

                switch (ELF32_R_TYPE(rel[i].r_info)) {
                case R_CSKY_32:
                        /* We add the value into the location given */
                        *location = rel[i].r_addend + sym->st_value;
                        break;
                case R_CSKY_PC32:
                        /* Add the value, subtract its position */
                        *location = rel[i].r_addend + sym->st_value
                                                        - (uint32_t)location;
                        break;
                case R_CSKY_PCRELJSR_IMM11BY2:
                        break;
                case R_CSKY_PCRELJSR_IMM26BY2:
                        jsri_2_lrw_jsr(location);
                        break;
                case R_CSKY_ADDR_HI16:
                        temp = ((short  *)location) + 1;
                        *temp = (short)
                                ((rel[i].r_addend + sym->st_value) >> 16);
                        break;
                case R_CSKY_ADDR_LO16:
                        temp = ((short  *)location) + 1;
                        *temp = (short)
                                ((rel[i].r_addend + sym->st_value) & 0xffff);
                        break;
                default:
                        pr_err("module %s: Unknown relocation: %u\n",
                                me->name, ELF32_R_TYPE(rel[i].r_info));
                        return -ENOEXEC;
                }
        }
        return 0;
}