root/arch/riscv/include/asm/module.h

INCLUDED FROM

DEFINITIONS

1. emit_got_entry
2. get_got_entry
3. emit_plt_entry
4. get_got_plt_idx
5. get_plt_entry

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /* Copyright (C) 2017 Andes Technology Corporation */
   3 
   4 #ifndef _ASM_RISCV_MODULE_H
   5 #define _ASM_RISCV_MODULE_H
   6 
   7 #include <asm-generic/module.h>
   8 
   9 #define MODULE_ARCH_VERMAGIC    "riscv"
  10 
  11 struct module;
  12 unsigned long module_emit_got_entry(struct module *mod, unsigned long val);
  13 unsigned long module_emit_plt_entry(struct module *mod, unsigned long val);
  14 
  15 #ifdef CONFIG_MODULE_SECTIONS
  16 struct mod_section {
  17         Elf_Shdr *shdr;
  18         int num_entries;
  19         int max_entries;
  20 };
  21 
  22 struct mod_arch_specific {
  23         struct mod_section got;
  24         struct mod_section plt;
  25         struct mod_section got_plt;
  26 };
  27 
  28 struct got_entry {
  29         unsigned long symbol_addr;      /* the real variable address */
  30 };
  31 
  32 static inline struct got_entry emit_got_entry(unsigned long val)
  33 {
  34         return (struct got_entry) {val};
  35 }
  36 
  37 static inline struct got_entry *get_got_entry(unsigned long val,
  38                                               const struct mod_section *sec)
  39 {
  40         struct got_entry *got = (struct got_entry *)(sec->shdr->sh_addr);
  41         int i;
  42         for (i = 0; i < sec->num_entries; i++) {
  43                 if (got[i].symbol_addr == val)
  44                         return &got[i];
  45         }
  46         return NULL;
  47 }
  48 
  49 struct plt_entry {
  50         /*
  51          * Trampoline code to real target address. The return address
  52          * should be the original (pc+4) before entring plt entry.
  53          */
  54         u32 insn_auipc;         /* auipc t0, 0x0                       */
  55         u32 insn_ld;            /* ld    t1, 0x10(t0)                  */
  56         u32 insn_jr;            /* jr    t1                            */
  57 };
  58 
  59 #define OPC_AUIPC  0x0017
  60 #define OPC_LD     0x3003
  61 #define OPC_JALR   0x0067
  62 #define REG_T0     0x5
  63 #define REG_T1     0x6
  64 
  65 static inline struct plt_entry emit_plt_entry(unsigned long val,
  66                                               unsigned long plt,
  67                                               unsigned long got_plt)
  68 {
  69         /*
  70          * U-Type encoding:
  71          * +------------+----------+----------+
  72          * | imm[31:12] | rd[11:7] | opc[6:0] |
  73          * +------------+----------+----------+
  74          *
  75          * I-Type encoding:
  76          * +------------+------------+--------+----------+----------+
  77          * | imm[31:20] | rs1[19:15] | funct3 | rd[11:7] | opc[6:0] |
  78          * +------------+------------+--------+----------+----------+
  79          *
  80          */
  81         unsigned long offset = got_plt - plt;
  82         u32 hi20 = (offset + 0x800) & 0xfffff000;
  83         u32 lo12 = (offset - hi20);
  84         return (struct plt_entry) {
  85                 OPC_AUIPC | (REG_T0 << 7) | hi20,
  86                 OPC_LD | (lo12 << 20) | (REG_T0 << 15) | (REG_T1 << 7),
  87                 OPC_JALR | (REG_T1 << 15)
  88         };
  89 }
  90 
  91 static inline int get_got_plt_idx(unsigned long val, const struct mod_section *sec)
  92 {
  93         struct got_entry *got_plt = (struct got_entry *)sec->shdr->sh_addr;
  94         int i;
  95         for (i = 0; i < sec->num_entries; i++) {
  96                 if (got_plt[i].symbol_addr == val)
  97                         return i;
  98         }
  99         return -1;
 100 }
 101 
 102 static inline struct plt_entry *get_plt_entry(unsigned long val,
 103                                               const struct mod_section *sec_plt,
 104                                               const struct mod_section *sec_got_plt)
 105 {
 106         struct plt_entry *plt = (struct plt_entry *)sec_plt->shdr->sh_addr;
 107         int got_plt_idx = get_got_plt_idx(val, sec_got_plt);
 108         if (got_plt_idx >= 0)
 109                 return plt + got_plt_idx;
 110         else
 111                 return NULL;
 112 }
 113 
 114 #endif /* CONFIG_MODULE_SECTIONS */
 115 
 116 #endif /* _ASM_RISCV_MODULE_H */