arch/riscv/include/asm/module.h

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