[331] | 1 | #ifdef TARGET_DEFS_ONLY
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| 2 |
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| 3 | #define EM_TCC_TARGET EM_ARM
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| 4 |
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| 5 | /* relocation type for 32 bit data relocation */
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| 6 | #define R_DATA_32 R_ARM_ABS32
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| 7 | #define R_DATA_PTR R_ARM_ABS32
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| 8 | #define R_JMP_SLOT R_ARM_JUMP_SLOT
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| 9 | #define R_GLOB_DAT R_ARM_GLOB_DAT
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| 10 | #define R_COPY R_ARM_COPY
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| 11 | #define R_RELATIVE R_ARM_RELATIVE
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| 12 |
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| 13 | #define R_NUM R_ARM_NUM
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| 14 |
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| 15 | #define ELF_START_ADDR 0x00008000
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| 16 | #define ELF_PAGE_SIZE 0x1000
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| 17 |
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| 18 | #define PCRELATIVE_DLLPLT 1
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| 19 | #define RELOCATE_DLLPLT 0
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| 20 |
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| 21 | enum float_abi {
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| 22 | ARM_SOFTFP_FLOAT,
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| 23 | ARM_HARD_FLOAT,
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| 24 | };
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| 25 |
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| 26 | #else /* !TARGET_DEFS_ONLY */
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| 27 |
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| 28 | #include "tcc.h"
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| 29 |
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| 30 | /* Returns 1 for a code relocation, 0 for a data relocation. For unknown
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| 31 | relocations, returns -1. */
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| 32 | int code_reloc (int reloc_type)
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| 33 | {
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| 34 | switch (reloc_type) {
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| 35 | case R_ARM_MOVT_ABS:
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| 36 | case R_ARM_MOVW_ABS_NC:
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| 37 | case R_ARM_THM_MOVT_ABS:
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| 38 | case R_ARM_THM_MOVW_ABS_NC:
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| 39 | case R_ARM_ABS32:
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| 40 | case R_ARM_REL32:
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| 41 | case R_ARM_GOTPC:
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| 42 | case R_ARM_GOTOFF:
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| 43 | case R_ARM_GOT32:
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| 44 | case R_ARM_COPY:
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| 45 | case R_ARM_GLOB_DAT:
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| 46 | case R_ARM_NONE:
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| 47 | return 0;
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| 48 |
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| 49 | case R_ARM_PC24:
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| 50 | case R_ARM_CALL:
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| 51 | case R_ARM_JUMP24:
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| 52 | case R_ARM_PLT32:
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| 53 | case R_ARM_THM_PC22:
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| 54 | case R_ARM_THM_JUMP24:
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| 55 | case R_ARM_PREL31:
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| 56 | case R_ARM_V4BX:
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| 57 | case R_ARM_JUMP_SLOT:
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| 58 | return 1;
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| 59 | }
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| 60 |
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| 61 | tcc_error ("Unknown relocation type: %d", reloc_type);
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| 62 | return -1;
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| 63 | }
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| 64 |
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| 65 | /* Returns an enumerator to describe whether and when the relocation needs a
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| 66 | GOT and/or PLT entry to be created. See tcc.h for a description of the
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| 67 | different values. */
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| 68 | int gotplt_entry_type (int reloc_type)
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| 69 | {
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| 70 | switch (reloc_type) {
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| 71 | case R_ARM_NONE:
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| 72 | case R_ARM_COPY:
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| 73 | case R_ARM_GLOB_DAT:
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| 74 | case R_ARM_JUMP_SLOT:
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| 75 | return NO_GOTPLT_ENTRY;
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| 76 |
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| 77 | case R_ARM_PC24:
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| 78 | case R_ARM_CALL:
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| 79 | case R_ARM_JUMP24:
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| 80 | case R_ARM_PLT32:
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| 81 | case R_ARM_THM_PC22:
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| 82 | case R_ARM_THM_JUMP24:
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| 83 | case R_ARM_MOVT_ABS:
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| 84 | case R_ARM_MOVW_ABS_NC:
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| 85 | case R_ARM_THM_MOVT_ABS:
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| 86 | case R_ARM_THM_MOVW_ABS_NC:
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| 87 | case R_ARM_PREL31:
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| 88 | case R_ARM_ABS32:
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| 89 | case R_ARM_REL32:
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| 90 | case R_ARM_V4BX:
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| 91 | return AUTO_GOTPLT_ENTRY;
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| 92 |
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| 93 | case R_ARM_GOTPC:
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| 94 | case R_ARM_GOTOFF:
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| 95 | return BUILD_GOT_ONLY;
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| 96 |
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| 97 | case R_ARM_GOT32:
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| 98 | return ALWAYS_GOTPLT_ENTRY;
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| 99 | }
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| 100 |
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| 101 | tcc_error ("Unknown relocation type: %d", reloc_type);
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| 102 | return -1;
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| 103 | }
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| 104 |
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| 105 | ST_FUNC unsigned create_plt_entry(TCCState *s1, unsigned got_offset, struct sym_attr *attr)
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| 106 | {
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| 107 | Section *plt = s1->plt;
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| 108 | uint8_t *p;
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| 109 | unsigned plt_offset;
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| 110 |
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| 111 | /* when building a DLL, GOT entry accesses must be done relative to
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| 112 | start of GOT (see x86_64 example above) */
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| 113 | if (s1->output_type == TCC_OUTPUT_DLL)
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| 114 | tcc_error("DLLs unimplemented!");
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| 115 |
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| 116 | /* empty PLT: create PLT0 entry that push address of call site and
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| 117 | jump to ld.so resolution routine (GOT + 8) */
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| 118 | if (plt->data_offset == 0) {
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| 119 | p = section_ptr_add(plt, 20);
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| 120 | write32le(p, 0xe52de004); /* push {lr} */
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| 121 | write32le(p+4, 0xe59fe004); /* ldr lr, [pc, #4] */
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| 122 | write32le(p+8, 0xe08fe00e); /* add lr, pc, lr */
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| 123 | write32le(p+12, 0xe5bef008); /* ldr pc, [lr, #8]! */
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| 124 | /* p+16 is set in relocate_plt */
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| 125 | }
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| 126 | plt_offset = plt->data_offset;
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| 127 |
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| 128 | if (attr->plt_thumb_stub) {
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| 129 | p = section_ptr_add(plt, 4);
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| 130 | write32le(p, 0x4778); /* bx pc */
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| 131 | write32le(p+2, 0x46c0); /* nop */
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| 132 | }
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| 133 | p = section_ptr_add(plt, 16);
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| 134 | /* Jump to GOT entry where ld.so initially put address of PLT0 */
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| 135 | write32le(p, 0xe59fc004); /* ldr ip, [pc, #4] */
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| 136 | write32le(p+4, 0xe08fc00c); /* add ip, pc, ip */
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| 137 | write32le(p+8, 0xe59cf000); /* ldr pc, [ip] */
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| 138 | /* p + 12 contains offset to GOT entry once patched by relocate_plt */
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| 139 | write32le(p+12, got_offset);
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| 140 | return plt_offset;
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| 141 | }
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| 142 |
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| 143 | /* relocate the PLT: compute addresses and offsets in the PLT now that final
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| 144 | address for PLT and GOT are known (see fill_program_header) */
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| 145 | ST_FUNC void relocate_plt(TCCState *s1)
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| 146 | {
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| 147 | uint8_t *p, *p_end;
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| 148 |
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| 149 | if (!s1->plt)
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| 150 | return;
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| 151 |
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| 152 | p = s1->plt->data;
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| 153 | p_end = p + s1->plt->data_offset;
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| 154 |
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| 155 | if (p < p_end) {
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| 156 | int x = s1->got->sh_addr - s1->plt->sh_addr - 12;
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| 157 | write32le(s1->plt->data + 16, x - 16);
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| 158 | p += 20;
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| 159 | while (p < p_end) {
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| 160 | if (read32le(p) == 0x46c04778) /* PLT Thumb stub present */
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| 161 | p += 4;
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| 162 | add32le(p + 12, x + s1->plt->data - p);
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| 163 | p += 16;
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| 164 | }
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| 165 | }
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| 166 | }
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| 167 |
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| 168 | void relocate_init(Section *sr) {}
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| 169 |
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| 170 | void relocate(TCCState *s1, ElfW_Rel *rel, int type, unsigned char *ptr, addr_t addr, addr_t val)
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| 171 | {
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| 172 | ElfW(Sym) *sym;
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| 173 | int sym_index;
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| 174 |
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| 175 | sym_index = ELFW(R_SYM)(rel->r_info);
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| 176 | sym = &((ElfW(Sym) *)symtab_section->data)[sym_index];
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| 177 |
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| 178 | switch(type) {
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| 179 | case R_ARM_PC24:
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| 180 | case R_ARM_CALL:
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| 181 | case R_ARM_JUMP24:
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| 182 | case R_ARM_PLT32:
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| 183 | {
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| 184 | int x, is_thumb, is_call, h, blx_avail, is_bl, th_ko;
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| 185 | x = (*(int *) ptr) & 0xffffff;
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| 186 | #ifdef DEBUG_RELOC
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| 187 | printf ("reloc %d: x=0x%x val=0x%x ", type, x, val);
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| 188 | #endif
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| 189 | (*(int *)ptr) &= 0xff000000;
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| 190 | if (x & 0x800000)
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| 191 | x -= 0x1000000;
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| 192 | x <<= 2;
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| 193 | blx_avail = (TCC_CPU_VERSION >= 5);
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| 194 | is_thumb = val & 1;
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| 195 | is_bl = (*(unsigned *) ptr) >> 24 == 0xeb;
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| 196 | is_call = (type == R_ARM_CALL || (type == R_ARM_PC24 && is_bl));
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| 197 | x += val - addr;
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| 198 | #ifdef DEBUG_RELOC
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| 199 | printf (" newx=0x%x name=%s\n", x,
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| 200 | (char *) symtab_section->link->data + sym->st_name);
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| 201 | #endif
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| 202 | h = x & 2;
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| 203 | th_ko = (x & 3) && (!blx_avail || !is_call);
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| 204 | if (th_ko || x >= 0x2000000 || x < -0x2000000)
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| 205 | tcc_error("can't relocate value at %x,%d",addr, type);
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| 206 | x >>= 2;
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| 207 | x &= 0xffffff;
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| 208 | /* Only reached if blx is avail and it is a call */
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| 209 | if (is_thumb) {
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| 210 | x |= h << 24;
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| 211 | (*(int *)ptr) = 0xfa << 24; /* bl -> blx */
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| 212 | }
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| 213 | (*(int *) ptr) |= x;
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| 214 | }
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| 215 | return;
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| 216 | /* Since these relocations only concern Thumb-2 and blx instruction was
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| 217 | introduced before Thumb-2, we can assume blx is available and not
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| 218 | guard its use */
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| 219 | case R_ARM_THM_PC22:
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| 220 | case R_ARM_THM_JUMP24:
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| 221 | {
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| 222 | int x, hi, lo, s, j1, j2, i1, i2, imm10, imm11;
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| 223 | int to_thumb, is_call, to_plt, blx_bit = 1 << 12;
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| 224 | Section *plt;
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| 225 |
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| 226 | /* weak reference */
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| 227 | if (sym->st_shndx == SHN_UNDEF &&
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| 228 | ELFW(ST_BIND)(sym->st_info) == STB_WEAK)
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| 229 | return;
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| 230 |
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| 231 | /* Get initial offset */
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| 232 | hi = (*(uint16_t *)ptr);
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| 233 | lo = (*(uint16_t *)(ptr+2));
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| 234 | s = (hi >> 10) & 1;
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| 235 | j1 = (lo >> 13) & 1;
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| 236 | j2 = (lo >> 11) & 1;
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| 237 | i1 = (j1 ^ s) ^ 1;
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| 238 | i2 = (j2 ^ s) ^ 1;
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| 239 | imm10 = hi & 0x3ff;
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| 240 | imm11 = lo & 0x7ff;
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| 241 | x = (s << 24) | (i1 << 23) | (i2 << 22) |
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| 242 | (imm10 << 12) | (imm11 << 1);
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| 243 | if (x & 0x01000000)
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| 244 | x -= 0x02000000;
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| 245 |
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| 246 | /* Relocation infos */
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| 247 | to_thumb = val & 1;
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| 248 | plt = s1->plt;
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| 249 | to_plt = (val >= plt->sh_addr) &&
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| 250 | (val < plt->sh_addr + plt->data_offset);
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| 251 | is_call = (type == R_ARM_THM_PC22);
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| 252 |
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| 253 | if (!to_thumb && !to_plt && !is_call) {
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| 254 | int index;
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| 255 | uint8_t *p;
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| 256 | char *name, buf[1024];
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| 257 | Section *text_section;
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| 258 |
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| 259 | name = (char *) symtab_section->link->data + sym->st_name;
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| 260 | text_section = s1->sections[sym->st_shndx];
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| 261 | /* Modify reloc to target a thumb stub to switch to ARM */
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| 262 | snprintf(buf, sizeof(buf), "%s_from_thumb", name);
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| 263 | index = put_elf_sym(symtab_section,
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| 264 | text_section->data_offset + 1,
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| 265 | sym->st_size, sym->st_info, 0,
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| 266 | sym->st_shndx, buf);
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| 267 | to_thumb = 1;
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| 268 | val = text_section->data_offset + 1;
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| 269 | rel->r_info = ELFW(R_INFO)(index, type);
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| 270 | /* Create a thumb stub function to switch to ARM mode */
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| 271 | put_elf_reloc(symtab_section, text_section,
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| 272 | text_section->data_offset + 4, R_ARM_JUMP24,
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| 273 | sym_index);
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| 274 | p = section_ptr_add(text_section, 8);
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| 275 | write32le(p, 0x4778); /* bx pc */
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| 276 | write32le(p+2, 0x46c0); /* nop */
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| 277 | write32le(p+4, 0xeafffffe); /* b $sym */
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| 278 | }
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| 279 |
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| 280 | /* Compute final offset */
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| 281 | x += val - addr;
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| 282 | if (!to_thumb && is_call) {
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| 283 | blx_bit = 0; /* bl -> blx */
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| 284 | x = (x + 3) & -4; /* Compute offset from aligned PC */
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| 285 | }
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| 286 |
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| 287 | /* Check that relocation is possible
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| 288 | * offset must not be out of range
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| 289 | * if target is to be entered in arm mode:
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| 290 | - bit 1 must not set
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| 291 | - instruction must be a call (bl) or a jump to PLT */
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| 292 | if (!to_thumb || x >= 0x1000000 || x < -0x1000000)
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| 293 | if (to_thumb || (val & 2) || (!is_call && !to_plt))
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| 294 | tcc_error("can't relocate value at %x,%d",addr, type);
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| 295 |
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| 296 | /* Compute and store final offset */
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| 297 | s = (x >> 24) & 1;
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| 298 | i1 = (x >> 23) & 1;
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| 299 | i2 = (x >> 22) & 1;
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| 300 | j1 = s ^ (i1 ^ 1);
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| 301 | j2 = s ^ (i2 ^ 1);
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| 302 | imm10 = (x >> 12) & 0x3ff;
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| 303 | imm11 = (x >> 1) & 0x7ff;
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| 304 | (*(uint16_t *)ptr) = (uint16_t) ((hi & 0xf800) |
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| 305 | (s << 10) | imm10);
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| 306 | (*(uint16_t *)(ptr+2)) = (uint16_t) ((lo & 0xc000) |
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| 307 | (j1 << 13) | blx_bit | (j2 << 11) |
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| 308 | imm11);
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| 309 | }
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| 310 | return;
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| 311 | case R_ARM_MOVT_ABS:
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| 312 | case R_ARM_MOVW_ABS_NC:
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| 313 | {
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| 314 | int x, imm4, imm12;
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| 315 | if (type == R_ARM_MOVT_ABS)
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| 316 | val >>= 16;
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| 317 | imm12 = val & 0xfff;
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| 318 | imm4 = (val >> 12) & 0xf;
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| 319 | x = (imm4 << 16) | imm12;
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| 320 | if (type == R_ARM_THM_MOVT_ABS)
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| 321 | *(int *)ptr |= x;
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| 322 | else
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| 323 | *(int *)ptr += x;
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| 324 | }
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| 325 | return;
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| 326 | case R_ARM_THM_MOVT_ABS:
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| 327 | case R_ARM_THM_MOVW_ABS_NC:
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| 328 | {
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| 329 | int x, i, imm4, imm3, imm8;
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| 330 | if (type == R_ARM_THM_MOVT_ABS)
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| 331 | val >>= 16;
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| 332 | imm8 = val & 0xff;
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| 333 | imm3 = (val >> 8) & 0x7;
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| 334 | i = (val >> 11) & 1;
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| 335 | imm4 = (val >> 12) & 0xf;
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| 336 | x = (imm3 << 28) | (imm8 << 16) | (i << 10) | imm4;
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| 337 | if (type == R_ARM_THM_MOVT_ABS)
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| 338 | *(int *)ptr |= x;
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| 339 | else
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| 340 | *(int *)ptr += x;
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| 341 | }
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| 342 | return;
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| 343 | case R_ARM_PREL31:
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| 344 | {
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| 345 | int x;
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| 346 | x = (*(int *)ptr) & 0x7fffffff;
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| 347 | (*(int *)ptr) &= 0x80000000;
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| 348 | x = (x * 2) / 2;
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| 349 | x += val - addr;
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| 350 | if((x^(x>>1))&0x40000000)
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| 351 | tcc_error("can't relocate value at %x,%d",addr, type);
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| 352 | (*(int *)ptr) |= x & 0x7fffffff;
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| 353 | }
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| 354 | case R_ARM_ABS32:
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| 355 | *(int *)ptr += val;
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| 356 | return;
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| 357 | case R_ARM_REL32:
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| 358 | *(int *)ptr += val - addr;
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| 359 | return;
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| 360 | case R_ARM_GOTPC:
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| 361 | *(int *)ptr += s1->got->sh_addr - addr;
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| 362 | return;
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| 363 | case R_ARM_GOTOFF:
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| 364 | *(int *)ptr += val - s1->got->sh_addr;
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| 365 | return;
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| 366 | case R_ARM_GOT32:
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| 367 | /* we load the got offset */
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| 368 | *(int *)ptr += s1->sym_attrs[sym_index].got_offset;
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| 369 | return;
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| 370 | case R_ARM_COPY:
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| 371 | return;
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| 372 | case R_ARM_V4BX:
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| 373 | /* trade Thumb support for ARMv4 support */
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| 374 | if ((0x0ffffff0 & *(int*)ptr) == 0x012FFF10)
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| 375 | *(int*)ptr ^= 0xE12FFF10 ^ 0xE1A0F000; /* BX Rm -> MOV PC, Rm */
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| 376 | return;
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| 377 | case R_ARM_GLOB_DAT:
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| 378 | case R_ARM_JUMP_SLOT:
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| 379 | *(addr_t *)ptr = val;
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| 380 | return;
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| 381 | case R_ARM_NONE:
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| 382 | /* Nothing to do. Normally used to indicate a dependency
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| 383 | on a certain symbol (like for exception handling under EABI). */
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| 384 | return;
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| 385 | case R_ARM_RELATIVE:
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| 386 | #ifdef TCC_TARGET_PE
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| 387 | add32le(ptr, val - s1->pe_imagebase);
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| 388 | #endif
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| 389 | /* do nothing */
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| 390 | return;
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| 391 | default:
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| 392 | fprintf(stderr,"FIXME: handle reloc type %x at %x [%p] to %x\n",
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| 393 | type, (unsigned)addr, ptr, (unsigned)val);
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| 394 | return;
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| 395 | }
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| 396 | }
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| 397 |
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| 398 | #endif /* !TARGET_DEFS_ONLY */
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