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1 | /* | |
2 | * Copyright (C) 2017 Andes Technology | |
3 | * Chih-Mao Chen <cmchen@andestech.com> | |
4 | * | |
5 | * SPDX-License-Identifier: GPL-2.0+ | |
6 | * | |
7 | * Statically process runtime relocations on RISC-V ELF images | |
8 | * so that it can be directly executed when loaded at LMA | |
9 | * without fixup. Both RV32 and RV64 are supported. | |
10 | */ | |
11 | ||
12 | #define CONCAT_IMPL(x, y) x##y | |
13 | #define CONCAT(x, y) CONCAT_IMPL(x, y) | |
14 | #define CONCAT3(x, y, z) CONCAT(CONCAT(x, y), z) | |
15 | ||
16 | #define prelink_nn CONCAT(prelink, PRELINK_INC_BITS) | |
17 | #define uintnn_t CONCAT3(uint, PRELINK_INC_BITS, _t) | |
18 | #define get_offset_nn CONCAT(get_offset_, PRELINK_INC_BITS) | |
19 | #define Elf_Ehdr CONCAT3(Elf, PRELINK_INC_BITS, _Ehdr) | |
20 | #define Elf_Phdr CONCAT3(Elf, PRELINK_INC_BITS, _Phdr) | |
21 | #define Elf_Rela CONCAT3(Elf, PRELINK_INC_BITS, _Rela) | |
22 | #define Elf_Sym CONCAT3(Elf, PRELINK_INC_BITS, _Sym) | |
23 | #define Elf_Dyn CONCAT3(Elf, PRELINK_INC_BITS, _Dyn) | |
24 | #define Elf_Addr CONCAT3(Elf, PRELINK_INC_BITS, _Addr) | |
25 | #define ELF_R_TYPE CONCAT3(ELF, PRELINK_INC_BITS, _R_TYPE) | |
26 | #define ELF_R_SYM CONCAT3(ELF, PRELINK_INC_BITS, _R_SYM) | |
27 | ||
28 | static void* get_offset_nn (void* data, Elf_Phdr* phdrs, size_t phnum, Elf_Addr addr) | |
29 | { | |
30 | Elf_Phdr *p; | |
31 | ||
32 | for (p = phdrs; p < phdrs + phnum; ++p) | |
33 | if (p->p_vaddr <= addr && p->p_vaddr + p->p_memsz > addr) | |
34 | return data + p->p_offset + (addr - p->p_vaddr); | |
35 | ||
36 | return NULL; | |
37 | } | |
38 | ||
39 | static void prelink_nn(void *data) | |
40 | { | |
41 | Elf_Ehdr *ehdr = data; | |
42 | Elf_Phdr *p; | |
43 | Elf_Dyn *dyn; | |
44 | Elf_Rela *r; | |
45 | ||
46 | if (ehdr->e_machine != EM_RISCV) | |
47 | die("Machine type is not RISC-V"); | |
48 | ||
49 | Elf_Phdr *phdrs = data + ehdr->e_phoff; | |
50 | ||
51 | Elf_Dyn *dyns = NULL; | |
52 | for (p = phdrs; p < phdrs + ehdr->e_phnum; ++p) { | |
53 | if (p->p_type == PT_DYNAMIC) { | |
54 | dyns = data + p->p_offset; | |
55 | break; | |
56 | } | |
57 | } | |
58 | ||
59 | if (dyns == NULL) | |
60 | die("No dynamic section found"); | |
61 | ||
62 | Elf_Rela *rela_dyn = NULL; | |
63 | size_t rela_count = 0; | |
64 | Elf_Sym *dynsym = NULL; | |
65 | for (dyn = dyns;; ++dyn) { | |
66 | if (dyn->d_tag == DT_NULL) | |
67 | break; | |
68 | else if (dyn->d_tag == DT_RELA) | |
69 | rela_dyn = get_offset_nn(data, phdrs, ehdr->e_phnum, + dyn->d_un.d_ptr); | |
70 | else if (dyn->d_tag == DT_RELASZ) | |
71 | rela_count = dyn->d_un.d_val / sizeof(Elf_Rela); | |
72 | else if (dyn->d_tag == DT_SYMTAB) | |
73 | dynsym = get_offset_nn(data, phdrs, ehdr->e_phnum, + dyn->d_un.d_ptr); | |
74 | ||
75 | } | |
76 | ||
77 | if (rela_dyn == NULL) | |
78 | die("No .rela.dyn found"); | |
79 | ||
80 | if (dynsym == NULL) | |
81 | die("No .dynsym found"); | |
82 | ||
83 | for (r = rela_dyn; r < rela_dyn + rela_count; ++r) { | |
84 | void* buf = get_offset_nn(data, phdrs, ehdr->e_phnum, r->r_offset); | |
85 | ||
86 | if (buf == NULL) | |
87 | continue; | |
88 | ||
89 | if (ELF_R_TYPE(r->r_info) == R_RISCV_RELATIVE) | |
90 | *((uintnn_t*) buf) = r->r_addend; | |
91 | else if (ELF_R_TYPE(r->r_info) == R_RISCV_32) | |
92 | *((uint32_t*) buf) = dynsym[ELF_R_SYM(r->r_info)].st_value; | |
93 | else if (ELF_R_TYPE(r->r_info) == R_RISCV_64) | |
94 | *((uint64_t*) buf) = dynsym[ELF_R_SYM(r->r_info)].st_value; | |
95 | } | |
96 | } | |
97 | ||
98 | #undef prelink_nn | |
99 | #undef uintnn_t | |
100 | #undef get_offset_nn | |
101 | #undef Elf_Ehdr | |
102 | #undef Elf_Phdr | |
103 | #undef Elf_Rela | |
104 | #undef Elf_Sym | |
105 | #undef Elf_Dyn | |
106 | #undef Elf_Addr | |
107 | #undef ELF_R_TYPE | |
108 | #undef ELF_R_SYM | |
109 | ||
110 | #undef CONCAT_IMPL | |
111 | #undef CONCAT | |
112 | #undef CONCAT3 |