path: root/ldso/dynlink.c
diff options
authorSamuel Holland <>2019-06-30 07:39:20 -0500
committerRich Felker <>2019-08-11 17:43:57 -0400
commit08869deb7efbda6e979886cb67e3d5843f92c2e8 (patch)
tree93547135ee0d59dd87831e8728f9c154e3d8e79e /ldso/dynlink.c
parent71af5309874269bcc9e4b84ea716fab33d888c1d (diff)
add support for powerpc/powerpc64 unaligned relocations
R_PPC_UADDR32 (R_PPC64_UADDR64) has the same meaning as R_PPC_ADDR32 (R_PPC64_ADDR64), except that its address need not be aligned. For powerpc64, BFD ld(1) will automatically convert between ADDR<->UADDR relocations when the address is/isn't at its native alignment. This will happen if, for example, there is a pointer in a packed struct. gold and lld do not currently generate R_PPC64_UADDR64, but pass through misaligned R_PPC64_ADDR64 relocations from object files, possibly relaxing them to misaligned R_PPC64_RELATIVE. In both cases (relaxed or not) this violates the PSABI, which defines the relevant field type as "a 64-bit field occupying 8 bytes, the alignment of which is 8 bytes unless otherwise specified." All three linkers violate the PSABI on 32-bit powerpc, where the only difference is that the field is 32 bits wide, aligned to 4 bytes. Currently musl fails to load executables linked by BFD ld containing R_PPC64_UADDR64, with the error "unsupported relocation type 43". This change provides compatibility with BFD ld on powerpc64, and any static linker on either architecture that starts following the PSABI more closely.
Diffstat (limited to 'ldso/dynlink.c')
1 files changed, 3 insertions, 0 deletions
diff --git a/ldso/dynlink.c b/ldso/dynlink.c
index 531811cc..edd91acd 100644
--- a/ldso/dynlink.c
+++ b/ldso/dynlink.c
@@ -407,6 +407,9 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri
case REL_PLT:
*reloc_addr = sym_val + addend;
+ memcpy(reloc_addr, &(size_t){sym_val + addend}, sizeof(size_t));
+ break;
*reloc_addr = (size_t)base + addend;