diff options
Diffstat (limited to 'sysdeps')
| -rw-r--r-- | sysdeps/powerpc/powerpc64/dl-machine.h | 49 |
1 files changed, 27 insertions, 22 deletions
diff --git a/sysdeps/powerpc/powerpc64/dl-machine.h b/sysdeps/powerpc/powerpc64/dl-machine.h index 89a69e1a23..c837393d79 100644 --- a/sysdeps/powerpc/powerpc64/dl-machine.h +++ b/sysdeps/powerpc/powerpc64/dl-machine.h @@ -246,30 +246,35 @@ BODY_PREFIX "_dl_start_user:\n" \ " " END_2(_dl_start_user) "\n" \ " .popsection"); -/* Nonzero iff TYPE should not be allowed to resolve to one of - the main executable's symbols, as for a COPY reloc. */ -#define elf_machine_lookup_noexec_p(type) ((type) == R_PPC64_COPY) +/* ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve to + one of the main executable's symbols, as for a COPY reloc. + + To make function pointer comparisons work on most targets, the + relevant ABI states that the address of a non-local function in a + dynamically linked executable is the address of the PLT entry for + that function. This is quite reasonable since using the real + function address in a non-PIC executable would typically require + dynamic relocations in .text, something to be avoided. For such + functions, the linker emits a SHN_UNDEF symbol in the executable + with value equal to the PLT entry address. Normally, SHN_UNDEF + symbols have a value of zero, so this is a clue to ld.so that it + should treat these symbols specially. For relocations not in + ELF_RTYPE_CLASS_PLT (eg. those on function pointers), ld.so should + use the value of the executable SHN_UNDEF symbol, ie. the PLT entry + address. For relocations in ELF_RTYPE_CLASS_PLT (eg. the relocs in + the PLT itself), ld.so should use the value of the corresponding + defined symbol in the object that defines the function, ie. the + real function address. This complicates ld.so in that there are + now two possible values for a given symbol, and it gets even worse + because protected symbols need yet another set of rules. + + On PowerPC64 we don't need any of this. The linker won't emit + SHN_UNDEF symbols with non-zero values. ld.so can make all + relocations behave "normally", ie. always use the real address + like PLT relocations. So always set ELF_RTYPE_CLASS_PLT. */ -/* Nonzero iff TYPE describes relocation of a PLT entry, so - PLT entries should not be allowed to define the value. */ -#define elf_machine_lookup_noplt_p(type) ((type) == R_PPC64_JMP_SLOT) - -/* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry, so - PLT entries should not be allowed to define the value. - ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve to one - of the main executable's symbols, as for a COPY reloc. */ - -#if !defined RTLD_BOOTSTRAP || USE___THREAD -#define elf_machine_type_class(type) \ - /* This covers all the TLS relocs, though most won't appear. */ \ - (((((type) >= R_PPC64_DTPMOD64 && (type) <= R_PPC64_TPREL16_HIGHESTA) \ - || (type) == R_PPC64_ADDR24) * ELF_RTYPE_CLASS_PLT) \ - | (((type) == R_PPC64_COPY) * ELF_RTYPE_CLASS_COPY)) -#else #define elf_machine_type_class(type) \ - ((((type) == R_PPC64_ADDR24) * ELF_RTYPE_CLASS_PLT) \ - | (((type) == R_PPC64_COPY) * ELF_RTYPE_CLASS_COPY)) -#endif + (ELF_RTYPE_CLASS_PLT | (((type) == R_PPC64_COPY) * ELF_RTYPE_CLASS_COPY)) /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */ #define ELF_MACHINE_JMP_SLOT R_PPC64_JMP_SLOT |