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/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright (C) 2017 Andes Technology Corporation */
#ifndef _ASM_RISCV_MODULE_H
#define _ASM_RISCV_MODULE_H
#include <asm-generic/module.h>
#include <linux/elf.h>
struct module;
unsigned long module_emit_got_entry(struct module *mod, unsigned long val);
unsigned long module_emit_plt_entry(struct module *mod, unsigned long val);
#ifdef CONFIG_MODULE_SECTIONS
struct mod_section {
Elf_Shdr *shdr;
int num_entries;
int max_entries;
};
struct mod_arch_specific {
struct mod_section got;
struct mod_section plt;
struct mod_section got_plt;
};
struct got_entry {
unsigned long symbol_addr; /* the real variable address */
};
static inline struct got_entry emit_got_entry(unsigned long val)
{
return (struct got_entry) {val};
}
static inline struct got_entry *get_got_entry(unsigned long val,
const struct mod_section *sec)
{
struct got_entry *got = (struct got_entry *)(sec->shdr->sh_addr);
int i;
for (i = 0; i < sec->num_entries; i++) {
if (got[i].symbol_addr == val)
return &got[i];
}
return NULL;
}
struct plt_entry {
/*
* Trampoline code to real target address. The return address
* should be the original (pc+4) before entring plt entry.
*/
u32 insn_auipc; /* auipc t0, 0x0 */
u32 insn_ld; /* ld t1, 0x10(t0) */
u32 insn_jr; /* jr t1 */
};
#define OPC_AUIPC 0x0017
#define OPC_LD 0x3003
#define OPC_JALR 0x0067
#define REG_T0 0x5
#define REG_T1 0x6
static inline struct plt_entry emit_plt_entry(unsigned long val,
unsigned long plt,
unsigned long got_plt)
{
/*
* U-Type encoding:
* +------------+----------+----------+
* | imm[31:12] | rd[11:7] | opc[6:0] |
* +------------+----------+----------+
*
* I-Type encoding:
* +------------+------------+--------+----------+----------+
* | imm[31:20] | rs1[19:15] | funct3 | rd[11:7] | opc[6:0] |
* +------------+------------+--------+----------+----------+
*
*/
unsigned long offset = got_plt - plt;
u32 hi20 = (offset + 0x800) & 0xfffff000;
u32 lo12 = (offset - hi20);
return (struct plt_entry) {
OPC_AUIPC | (REG_T0 << 7) | hi20,
OPC_LD | (lo12 << 20) | (REG_T0 << 15) | (REG_T1 << 7),
OPC_JALR | (REG_T1 << 15)
};
}
static inline int get_got_plt_idx(unsigned long val, const struct mod_section *sec)
{
struct got_entry *got_plt = (struct got_entry *)sec->shdr->sh_addr;
int i;
for (i = 0; i < sec->num_entries; i++) {
if (got_plt[i].symbol_addr == val)
return i;
}
return -1;
}
static inline struct plt_entry *get_plt_entry(unsigned long val,
const struct mod_section *sec_plt,
const struct mod_section *sec_got_plt)
{
struct plt_entry *plt = (struct plt_entry *)sec_plt->shdr->sh_addr;
int got_plt_idx = get_got_plt_idx(val, sec_got_plt);
if (got_plt_idx >= 0)
return plt + got_plt_idx;
else
return NULL;
}
#endif /* CONFIG_MODULE_SECTIONS */
static inline const Elf_Shdr *find_section(const Elf_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;
}
#endif /* _ASM_RISCV_MODULE_H */
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