Avoid using the global offset table to get the address of _DYNAMIC in

rtld.  When _DYNAMIC is referenced normally from C the global offset
table is used implicitly, but newer versions of binutils don't initialize
it statically in the binary, so this doesn't work until rtld is relocated,
which _DYNAMIC is needed for...  So, as on other systems with the same
problem, we disassemble a call instruction to _DYNAMIC in order to get
its address.

2 files changed, 18 insertions, 1 deletions

diff --git a/libexec/rtld-elf/sparc64/rtld_machdep.h b/libexec/rtld-elf/sparc64/rtld_machdep.h
index 9efadca..d92055c 100644
--- a/libexec/rtld-elf/sparc64/rtld_machdep.h
+++ b/libexec/rtld-elf/sparc64/rtld_machdep.h
@@ -37,7 +37,7 @@
 struct Struct_Obj_Entry;
 
 /* Return the address of the .dynamic section in the dynamic linker. */
-#define rtld_dynamic(obj)	((Elf_Dyn *)(((char *)&_DYNAMIC) + (vm_offset_t)(obj)->relocbase))
+Elf_Dyn *rtld_dynamic(const struct Struct_Obj_Entry *);
 
 Elf_Addr reloc_jmpslot(Elf_Addr *, Elf_Addr,
 		       const struct Struct_Obj_Entry *,
diff --git a/libexec/rtld-elf/sparc64/rtld_start.S b/libexec/rtld-elf/sparc64/rtld_start.S
index f9d05b7..146c6314 100644
--- a/libexec/rtld-elf/sparc64/rtld_start.S
+++ b/libexec/rtld-elf/sparc64/rtld_start.S
@@ -67,6 +67,23 @@ ENTRY(.rtld_start)
 	 mov	%l0, %o0
 END(.rtld_start)
 
+/*
+ * Find the address of _DYNAMIC by disassembling a call instruction to it.
+ * Binutils may not fill in the GOT as expected on other architectures.
+ */
+
+ENTRY(rtld_dynamic)
+	save	%sp, -CCFSZ, %sp
+	call	1f
+	 nop
+	call	_DYNAMIC + 8
+1:	lduw	[%o7 + 8], %o0
+	sll	%o0, 2, %o0
+	sra	%o0, 0, %o0
+	ret
+	 restore %o0, %o7, %o0
+END(rtld_dynamic)
+
 	/*
 	 * We have two separate entry points to the runtime linker.
 	 * I'm implementing this following the SPARC v9 ABI spec.