PowerPC64 ELFv2 PPC64_OPT_LOCALENTRY

ELFv2 functions with localentry:0 are those with a single entry point,
ie. global entry == local entry, that have no requirement on r2 or
r12 and guarantee r2 is unchanged on return.  Such an external
function can be called via the PLT without saving r2 or restoring it
on return, avoiding a common load-hit-store for small functions.

This patch implements the ld.so changes necessary for this
optimization.  ld.so needs to check that an optimized plt call
sequence is in fact calling a function implemented with localentry:0,
end emit a fatal error otherwise.

The elf/testobj6.c change is to stop "error while loading shared
libraries: expected localentry:0 `preload'" when running
elf/preloadtest, which we'd get otherwise.

	* elf/elf.h (PPC64_OPT_LOCALENTRY): Define.
	* sysdeps/alpha/dl-machine.h (elf_machine_fixup_plt): Add
	refsym and sym parameters.  Adjust callers.
	* sysdeps/aarch64/dl-machine.h (elf_machine_fixup_plt): Likewise.
	* sysdeps/arm/dl-machine.h (elf_machine_fixup_plt): Likewise.
	* sysdeps/generic/dl-machine.h (elf_machine_fixup_plt): Likewise.
	* sysdeps/hppa/dl-machine.h (elf_machine_fixup_plt): Likewise.
	* sysdeps/i386/dl-machine.h (elf_machine_fixup_plt): Likewise.
	* sysdeps/ia64/dl-machine.h (elf_machine_fixup_plt): Likewise.
	* sysdeps/m68k/dl-machine.h (elf_machine_fixup_plt): Likewise.
	* sysdeps/microblaze/dl-machine.h (elf_machine_fixup_plt): Likewise.
	* sysdeps/mips/dl-machine.h (elf_machine_fixup_plt): Likewise.
	* sysdeps/nios2/dl-machine.h (elf_machine_fixup_plt): Likewise.
	* sysdeps/powerpc/powerpc32/dl-machine.h (elf_machine_fixup_plt):
	Likewise.
	* sysdeps/s390/s390-32/dl-machine.h (elf_machine_fixup_plt): Likewise.
	* sysdeps/s390/s390-64/dl-machine.h (elf_machine_fixup_plt): Likewise.
	* sysdeps/sh/dl-machine.h (elf_machine_fixup_plt): Likewise.
	* sysdeps/sparc/sparc32/dl-machine.h (elf_machine_fixup_plt): Likewise.
	* sysdeps/sparc/sparc64/dl-machine.h (elf_machine_fixup_plt): Likewise.
	* sysdeps/tile/dl-machine.h (elf_machine_fixup_plt): Likewise.
	* sysdeps/x86_64/dl-machine.h (elf_machine_fixup_plt): Likewise.
	* sysdeps/powerpc/powerpc64/dl-machine.c (_dl_error_localentry): New.
	(_dl_reloc_overflow): Increase buffser size.  Formatting.
	* sysdeps/powerpc/powerpc64/dl-machine.h (ppc64_local_entry_offset):
	Delete reloc param, add refsym and sym.  Check optimized plt
	call stubs for localentry:0 functions.  Adjust callers.
	(elf_machine_fixup_plt, elf_machine_plt_conflict): Add refsym
	and sym parameters.  Adjust callers.
	(_dl_reloc_overflow): Move attribute.
	(_dl_error_localentry): Declare.
	* elf/dl-runtime.c (_dl_fixup): Save original sym.  Pass
	refsym and sym to elf_machine_fixup_plt.
	* elf/testobj6.c (preload): Call printf.

3 files changed, 7 insertions, 2 deletions

diff --git a/elf/dl-runtime.c b/elf/dl-runtime.c
index 7d1d240..51d3819 100644
--- a/elf/dl-runtime.c
+++ b/elf/dl-runtime.c
@@ -71,6 +71,7 @@ _dl_fixup (
   const PLTREL *const reloc
     = (const void *) (D_PTR (l, l_info[DT_JMPREL]) + reloc_offset);
   const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (reloc->r_info)];
+  const ElfW(Sym) *refsym = sym;
   void *const rel_addr = (void *)(l->l_addr + reloc->r_offset);
   lookup_t result;
   DL_FIXUP_VALUE_TYPE value;
@@ -145,7 +146,7 @@ _dl_fixup (
   if (__glibc_unlikely (GLRO(dl_bind_not)))
     return value;
 
-  return elf_machine_fixup_plt (l, result, reloc, rel_addr, value);
+  return elf_machine_fixup_plt (l, result, refsym, sym, reloc, rel_addr, value);
 }
 
 #ifndef PROF
diff --git a/elf/elf.h b/elf/elf.h
index fff893d..3900b4c 100644
--- a/elf/elf.h
+++ b/elf/elf.h
@@ -2544,9 +2544,10 @@ enum
 #define DT_PPC64_OPT	(DT_LOPROC + 3)
 #define DT_PPC64_NUM    4
 
-/* PowerPC64 specific values for the DT_PPC64_OPT Dyn entry.  */
+/* PowerPC64 specific bits in the DT_PPC64_OPT Dyn entry.  */
 #define PPC64_OPT_TLS		1
 #define PPC64_OPT_MULTI_TOC	2
+#define PPC64_OPT_LOCALENTRY	4
 
 /* PowerPC64 specific values for the Elf64_Sym st_other field.  */
 #define STO_PPC64_LOCAL_BIT	5
diff --git a/elf/testobj6.c b/elf/testobj6.c
index fcba016..84da4c9 100644
--- a/elf/testobj6.c
+++ b/elf/testobj6.c
@@ -1,3 +1,5 @@
+#include <stdio.h>
+
 #include "testobj.h"
 
 int
@@ -15,5 +17,6 @@ obj6func2 (int a)
 int
 preload (int a)
 {
+  printf ("testobj6 preload\n");
   return a;
 }