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Separate the function symbol address from .plt to .got.plt section. The original plt entry has trampoline code with symbol address, there is a 32-bit padding bwtween jar instruction and symbol address. Extract the symbol address to .got.plt to reduce the module size. Signed-off-by: Zong Li <zong@andestech.com> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
114 lines
2.8 KiB
C
114 lines
2.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/* Copyright (C) 2017 Andes Technology Corporation */
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#ifndef _ASM_RISCV_MODULE_H
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#define _ASM_RISCV_MODULE_H
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#include <asm-generic/module.h>
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#define MODULE_ARCH_VERMAGIC "riscv"
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u64 module_emit_got_entry(struct module *mod, u64 val);
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u64 module_emit_plt_entry(struct module *mod, u64 val);
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#ifdef CONFIG_MODULE_SECTIONS
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struct mod_section {
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struct elf64_shdr *shdr;
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int num_entries;
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int max_entries;
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};
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struct mod_arch_specific {
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struct mod_section got;
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struct mod_section plt;
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struct mod_section got_plt;
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};
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struct got_entry {
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u64 symbol_addr; /* the real variable address */
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};
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static inline struct got_entry emit_got_entry(u64 val)
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{
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return (struct got_entry) {val};
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}
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static inline struct got_entry *get_got_entry(u64 val,
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const struct mod_section *sec)
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{
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struct got_entry *got = (struct got_entry *)sec->shdr->sh_addr;
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int i;
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for (i = 0; i < sec->num_entries; i++) {
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if (got[i].symbol_addr == val)
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return &got[i];
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}
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return NULL;
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}
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struct plt_entry {
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/*
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* Trampoline code to real target address. The return address
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* should be the original (pc+4) before entring plt entry.
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*/
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u32 insn_auipc; /* auipc t0, 0x0 */
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u32 insn_ld; /* ld t1, 0x10(t0) */
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u32 insn_jr; /* jr t1 */
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};
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#define OPC_AUIPC 0x0017
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#define OPC_LD 0x3003
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#define OPC_JALR 0x0067
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#define REG_T0 0x5
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#define REG_T1 0x6
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static inline struct plt_entry emit_plt_entry(u64 val, u64 plt, u64 got_plt)
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{
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/*
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* U-Type encoding:
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* +------------+----------+----------+
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* | imm[31:12] | rd[11:7] | opc[6:0] |
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* +------------+----------+----------+
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*
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* I-Type encoding:
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* +------------+------------+--------+----------+----------+
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* | imm[31:20] | rs1[19:15] | funct3 | rd[11:7] | opc[6:0] |
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* +------------+------------+--------+----------+----------+
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*
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*/
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u64 offset = got_plt - plt;
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u32 hi20 = (offset + 0x800) & 0xfffff000;
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u32 lo12 = (offset - hi20);
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return (struct plt_entry) {
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OPC_AUIPC | (REG_T0 << 7) | hi20,
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OPC_LD | (lo12 << 20) | (REG_T0 << 15) | (REG_T1 << 7),
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OPC_JALR | (REG_T1 << 15)
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};
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}
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static inline int get_got_plt_idx(u64 val, const struct mod_section *sec)
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{
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struct got_entry *got_plt = (struct got_entry *)sec->shdr->sh_addr;
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int i;
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for (i = 0; i < sec->num_entries; i++) {
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if (got_plt[i].symbol_addr == val)
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return i;
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}
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return -1;
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}
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static inline struct plt_entry *get_plt_entry(u64 val,
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const struct mod_section *sec_plt,
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const struct mod_section *sec_got_plt)
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{
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struct plt_entry *plt = (struct plt_entry *)sec_plt->shdr->sh_addr;
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int got_plt_idx = get_got_plt_idx(val, sec_got_plt);
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if (got_plt_idx >= 0)
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return plt + got_plt_idx;
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else
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return NULL;
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}
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#endif /* CONFIG_MODULE_SECTIONS */
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#endif /* _ASM_RISCV_MODULE_H */
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