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https://github.com/frida/tinycc
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25927df3b7
Static relocation of functions in dynamic libraries must use the PLT entry as the target. Before this commit, it used to be done in 2 parts for ARM, with the offset of the PLT entry from the beginning of the PLT being put in the relocated place in build_got_entries () and then the address of the PLT being added in relocate_section. This led to code dealing with reading the offset of a bl instruction in build_got_entries. Furthermore, the addition of the address of the start of the PLT was done based on the relocation type which does not convey whether a PLT entry should be used to reach the symbol. This commit moves the decision to use the PLT as the target in relocate_section, therefore having the instruction aware code contained to the target-specific bit of that function (in <target>-link.c). Note that relocate_syms is *not* the right place to do this because two different relocations for the same symbol can make different decision. This is the case in tcc -run mode where the static and dynamic relocation are done by tcc. Storing the PLT entry address in the symbol's st_value field and relying on the specific relocation type being used for dynamic relocation would work but the PLT entry address would then appear in the static symbol table (symtab). This would also make the static symbol table entry differ from the dynamic symbol table entry.
114 lines
4.6 KiB
C
114 lines
4.6 KiB
C
#include "tcc.h"
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#define HAVE_SECTION_RELOC
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ST_DATA struct reloc_info relocs_info[] = {
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INIT_RELOC_INFO (R_AARCH64_ABS32, 0, NO_GOTPLT_ENTRY, 0)
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INIT_RELOC_INFO (R_AARCH64_ABS64, 0, NO_GOTPLT_ENTRY, 0)
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INIT_RELOC_INFO (R_AARCH64_MOVW_UABS_G0_NC, 0, NO_GOTPLT_ENTRY, 0)
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INIT_RELOC_INFO (R_AARCH64_MOVW_UABS_G1_NC, 0, NO_GOTPLT_ENTRY, 0)
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INIT_RELOC_INFO (R_AARCH64_MOVW_UABS_G2_NC, 0, NO_GOTPLT_ENTRY, 0)
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INIT_RELOC_INFO (R_AARCH64_MOVW_UABS_G3, 0, NO_GOTPLT_ENTRY, 0)
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INIT_RELOC_INFO (R_AARCH64_ADR_PREL_PG_HI21, 0, NO_GOTPLT_ENTRY, 0)
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INIT_RELOC_INFO (R_AARCH64_ADD_ABS_LO12_NC, 0, NO_GOTPLT_ENTRY, 0)
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INIT_RELOC_INFO (R_AARCH64_JUMP26, 1, AUTO_GOTPLT_ENTRY, 1)
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INIT_RELOC_INFO (R_AARCH64_CALL26, 1, AUTO_GOTPLT_ENTRY, 1)
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INIT_RELOC_INFO (R_AARCH64_ADR_GOT_PAGE, 0, ALWAYS_GOTPLT_ENTRY, 0)
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INIT_RELOC_INFO (R_AARCH64_LD64_GOT_LO12_NC, 0, ALWAYS_GOTPLT_ENTRY, 0)
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INIT_RELOC_INFO (R_AARCH64_GLOB_DAT, 0, NO_GOTPLT_ENTRY, 0)
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INIT_RELOC_INFO (R_AARCH64_JUMP_SLOT, 1, NO_GOTPLT_ENTRY, 0)
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};
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void relocate_init(Section *sr) {}
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void relocate(TCCState *s1, ElfW_Rel *rel, int type, char *ptr, addr_t addr, addr_t val)
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{
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ElfW(Sym) *sym;
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int sym_index;
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sym_index = ELFW(R_SYM)(rel->r_info);
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sym = &((ElfW(Sym) *)symtab_section->data)[sym_index];
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switch(type) {
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case R_AARCH64_ABS64:
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write64le(ptr, val);
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return;
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case R_AARCH64_ABS32:
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write32le(ptr, val);
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return;
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case R_AARCH64_MOVW_UABS_G0_NC:
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write32le(ptr, ((read32le(ptr) & 0xffe0001f) |
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(val & 0xffff) << 5));
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return;
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case R_AARCH64_MOVW_UABS_G1_NC:
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write32le(ptr, ((read32le(ptr) & 0xffe0001f) |
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(val >> 16 & 0xffff) << 5));
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return;
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case R_AARCH64_MOVW_UABS_G2_NC:
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write32le(ptr, ((read32le(ptr) & 0xffe0001f) |
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(val >> 32 & 0xffff) << 5));
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return;
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case R_AARCH64_MOVW_UABS_G3:
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write32le(ptr, ((read32le(ptr) & 0xffe0001f) |
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(val >> 48 & 0xffff) << 5));
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return;
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case R_AARCH64_ADR_PREL_PG_HI21: {
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uint64_t off = (val >> 12) - (addr >> 12);
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if ((off + ((uint64_t)1 << 20)) >> 21)
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tcc_error("R_AARCH64_ADR_PREL_PG_HI21 relocation failed");
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write32le(ptr, ((read32le(ptr) & 0x9f00001f) |
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(off & 0x1ffffc) << 3 | (off & 3) << 29));
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return;
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}
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case R_AARCH64_ADD_ABS_LO12_NC:
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write32le(ptr, ((read32le(ptr) & 0xffc003ff) |
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(val & 0xfff) << 10));
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return;
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case R_AARCH64_JUMP26:
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case R_AARCH64_CALL26:
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#ifdef DEBUG_RELOC
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printf ("reloc %d @ 0x%lx: val=0x%lx name=%s\n", type, addr, val,
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(char *) symtab_section->link->data + sym->st_name);
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#endif
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if (((val - addr) + ((uint64_t)1 << 27)) & ~(uint64_t)0xffffffc)
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{
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tcc_error("R_AARCH64_(JUMP|CALL)26 relocation failed (val=%lx, addr=%lx)", addr, val);
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}
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write32le(ptr, (0x14000000 |
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(uint32_t)(type == R_AARCH64_CALL26) << 31 |
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((val - addr) >> 2 & 0x3ffffff)));
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return;
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case R_AARCH64_ADR_GOT_PAGE: {
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uint64_t off =
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(((s1->got->sh_addr +
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s1->sym_attrs[sym_index].got_offset) >> 12) - (addr >> 12));
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if ((off + ((uint64_t)1 << 20)) >> 21)
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tcc_error("R_AARCH64_ADR_GOT_PAGE relocation failed");
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write32le(ptr, ((read32le(ptr) & 0x9f00001f) |
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(off & 0x1ffffc) << 3 | (off & 3) << 29));
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return;
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}
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case R_AARCH64_LD64_GOT_LO12_NC:
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write32le(ptr,
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((read32le(ptr) & 0xfff803ff) |
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((s1->got->sh_addr +
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s1->sym_attrs[sym_index].got_offset) & 0xff8) << 7));
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return;
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case R_AARCH64_COPY:
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return;
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case R_AARCH64_GLOB_DAT:
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case R_AARCH64_JUMP_SLOT:
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/* They don't need addend */
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#ifdef DEBUG_RELOC
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printf ("reloc %d @ 0x%lx: val=0x%lx name=%s\n", type, addr,
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val - rel->r_addend,
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(char *) symtab_section->link->data + sym->st_name);
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#endif
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write64le(ptr, val - rel->r_addend);
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return;
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default:
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fprintf(stderr, "FIXME: handle reloc type %x at %x [%p] to %x\n",
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type, (unsigned)addr, ptr, (unsigned)val);
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return;
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}
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}
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