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authorUlrich Drepper <drepper@redhat.com>2008-04-10 18:26:16 +0000
committerUlrich Drepper <drepper@redhat.com>2008-04-10 18:26:16 +0000
commitd2207f32b107509ff37a48409e586dbf0efdeba3 (patch)
tree8414aad35d040aedeb999e2549e9fe06c1e1b89a /sysdeps
parent13d83320ff876f3b5dbd646ad49598d5be8e42d6 (diff)
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* sysdeps/powerpc/powerpc64/dl-machine.h (elf_machine_type_class):
Always set ELF_RTYPE_CLASS_PLT. (elf_machine_lookup_noexec_p, elf_machine_lookup_noplt_p): Delete.
Diffstat (limited to 'sysdeps')
-rw-r--r--sysdeps/powerpc/powerpc64/dl-machine.h49
1 files changed, 27 insertions, 22 deletions
diff --git a/sysdeps/powerpc/powerpc64/dl-machine.h b/sysdeps/powerpc/powerpc64/dl-machine.h
index 89a69e1..c837393 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