# commit 696caf1d002ff059ddd20fd5eaccd76229c14850

# Author: Ulrich Weigand <Ulrich.Weigand@de.ibm.com>

# Date:   Wed Dec 4 06:51:11 2013 -0600

# 

#     PowerPC64 ELFv2 ABI 2/6: Remove function descriptors

#     

#     This patch adds support for the ELFv2 ABI feature to remove function

#     descriptors.  See this GCC patch for in-depth discussion:

#     http://gcc.gnu.org/ml/gcc-patches/2013-11/msg01141.html

#     

#     This mostly involves two types of changes: updating assembler source

#     files to the new logic, and updating the dynamic loader.

#     

#     After the refactoring in the previous patch, most of the assembler source

#     changes can be handled simply by providing ELFv2 versions of the

#     macros in sysdep.h.   One somewhat non-obvious change is in __GI__setjmp:

#     this used to "fall through" to the immediately following __setjmp ENTRY

#     point.  This is no longer safe in the ELFv2 since ENTRY defines both

#     a global and a local entry point, and you cannot simply fall through

#     to a global entry point as it requires r12 to be set up.

#     

#     Also, makecontext needs to be updated to set up registers according to

#     the new ABI for calling into the context's start routine.

#     

#     The dynamic linker changes mostly consist of removing special code

#     to handle function descriptors.  We also need to support the new PLT

#     and glink format used by the the ELFv2 linker, see:

#     https://sourceware.org/ml/binutils/2013-10/msg00376.html

#     

#     In addition, the dynamic linker now verifies that the dynamic libraries

#     it loads match its own ABI.

#     

#     The hack in VDSO_IFUNC_RET to "synthesize" a function descriptor

#     for vDSO routines is also no longer necessary for ELFv2.

# 

diff -urN glibc-2.17-c758a686/elf/elf.h glibc-2.17-c758a686/elf/elf.h

--- glibc-2.17-c758a686/elf/elf.h	2014-05-29 13:58:25.000000000 -0500

+++ glibc-2.17-c758a686/elf/elf.h	2014-05-29 13:58:25.000000000 -0500

@@ -2263,6 +2263,12 @@

 #define R_PPC64_REL16_HI	251	/* half16   (sym+add-.)@h */

 #define R_PPC64_REL16_HA	252	/* half16   (sym+add-.)@ha */

+/* e_flags bits specifying ABI.

+   1 for original function descriptor using ABI,

+   2 for revised ABI without function descriptors,

+   0 for unspecified or not using any features affected by the differences.  */

+#define EF_PPC64_ABI	3

+

 /* PowerPC64 specific values for the Dyn d_tag field.  */

 #define DT_PPC64_GLINK  (DT_LOPROC + 0)

 #define DT_PPC64_OPD	(DT_LOPROC + 1)

diff -urN glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/crti.S glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/crti.S

--- glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/crti.S	2014-05-29 13:58:25.000000000 -0500

+++ glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/crti.S	2014-05-29 13:58:25.000000000 -0500

@@ -64,6 +64,7 @@

 	ENTRY_2(_init)

 	.align ALIGNARG (2)

 BODY_LABEL (_init):

+	LOCALENTRY(_init)

 	mflr 0

 	std 0, 16(r1)

 	stdu r1, -112(r1)

@@ -81,6 +82,7 @@

 	ENTRY_2(_fini)

 	.align ALIGNARG (2)

 BODY_LABEL (_fini):

+	LOCALENTRY(_fini)

 	mflr 0

 	std 0, 16(r1)

 	stdu r1, -112(r1)

diff -urN glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/dl-irel.h glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/dl-irel.h

--- glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/dl-irel.h	2014-05-29 13:58:25.000000000 -0500

+++ glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/dl-irel.h	2014-05-29 13:58:25.000000000 -0500

@@ -50,7 +50,11 @@

     {

       Elf64_Addr *const reloc_addr = (void *) reloc->r_offset;

       Elf64_Addr value = elf_ifunc_invoke(reloc->r_addend);

+#if _CALL_ELF != 2

       *(Elf64_FuncDesc *) reloc_addr = *(Elf64_FuncDesc *) value;

+#else

+      *reloc_addr = value;

+#endif

     }

   else

     __libc_fatal ("unexpected reloc type in static binary");

diff -urN glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/dl-machine.h glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/dl-machine.h

--- glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/dl-machine.h	2014-05-29 13:58:25.000000000 -0500

+++ glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/dl-machine.h	2014-05-29 14:05:46.000000000 -0500

@@ -31,6 +31,7 @@

    in l_info array.  */

 #define DT_PPC64(x) (DT_PPC64_##x - DT_LOPROC + DT_NUM)

+#if _CALL_ELF != 2

 /* A PowerPC64 function descriptor.  The .plt (procedure linkage

    table) and .opd (official procedure descriptor) sections are

    arrays of these.  */

@@ -40,6 +41,7 @@

   Elf64_Addr fd_toc;

   Elf64_Addr fd_aux;

 } Elf64_FuncDesc;

+#endif

 #define ELF_MULT_MACHINES_SUPPORTED

@@ -47,6 +49,18 @@

 static inline int

 elf_machine_matches_host (const Elf64_Ehdr *ehdr)

 {

+  /* Verify that the binary matches our ABI version.  */

+  if ((ehdr->e_flags & EF_PPC64_ABI) != 0)

+    {

+#if _CALL_ELF != 2

+      if ((ehdr->e_flags & EF_PPC64_ABI) != 1)

+        return 0;

+#else

+      if ((ehdr->e_flags & EF_PPC64_ABI) != 2)

+        return 0;

+#endif

+    }

+

   return ehdr->e_machine == EM_PPC64;

 }

@@ -124,6 +138,7 @@

 "	.align	2\n"							\

 "	" ENTRY_2(_start) "\n"						\

 BODY_PREFIX "_start:\n"							\

+"	" LOCALENTRY(_start) "\n"						\

 /* We start with the following on the stack, from top:			\

    argc (4 bytes);							\

    arguments for program (terminated by NULL);				\

@@ -165,6 +180,7 @@

    Changing these is strongly discouraged (not least because argc is	\

    passed by value!).  */						\

 BODY_PREFIX "_dl_start_user:\n"						\

+"	" LOCALENTRY(_dl_start_user) "\n"				\

 /* the address of _start in r30.  */					\

 "	mr	30,3\n"							\

 /* &_dl_argc in 29, &_dl_argv in 27, and _dl_loaded in 28.  */		\

@@ -256,8 +272,22 @@

    relocations behave "normally", ie. always use the real address

    like PLT relocations.  So always set ELF_RTYPE_CLASS_PLT.  */

+#if _CALL_ELF != 2

 #define elf_machine_type_class(type) \

   (ELF_RTYPE_CLASS_PLT | (((type) == R_PPC64_COPY) * ELF_RTYPE_CLASS_COPY))

+#else

+/* And now that you have read that large comment, you can disregard it

+   all for ELFv2.  ELFv2 does need the special SHN_UNDEF treatment.  */

+#define IS_PPC64_TLS_RELOC(R)						\

+  (((R) >= R_PPC64_TLS && (R) <= R_PPC64_DTPREL16_HIGHESTA)		\

+   || ((R) >= R_PPC64_TPREL16_HIGH && (R) <= R_PPC64_DTPREL16_HIGHA))

+

+#define elf_machine_type_class(type) \

+  ((((type) == R_PPC64_JMP_SLOT					\

+     || (type) == R_PPC64_ADDR24				\

+     || IS_PPC64_TLS_RELOC (type)) * ELF_RTYPE_CLASS_PLT)	\

+   | (((type) == R_PPC64_COPY) * ELF_RTYPE_CLASS_COPY))

+#endif

 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */

 #define ELF_MACHINE_JMP_SLOT	R_PPC64_JMP_SLOT

@@ -266,8 +296,19 @@

 #define ELF_MACHINE_NO_REL 1

 /* Stuff for the PLT.  */

+#if _CALL_ELF != 2

 #define PLT_INITIAL_ENTRY_WORDS 3

+#define PLT_ENTRY_WORDS 3

 #define GLINK_INITIAL_ENTRY_WORDS 8

+/* The first 32k entries of glink can set an index and branch using two

+   instructions; past that point, glink uses three instructions.  */

+#define GLINK_ENTRY_WORDS(I) (((I) < 0x8000)? 2 : 3)

+#else

+#define PLT_INITIAL_ENTRY_WORDS 2

+#define PLT_ENTRY_WORDS 1

+#define GLINK_INITIAL_ENTRY_WORDS 8

+#define GLINK_ENTRY_WORDS(I) 1

+#endif

 #define PPC_DCBST(where) asm volatile ("dcbst 0,%0" : : "r"(where) : "memory")

 #define PPC_DCBT(where) asm volatile ("dcbt 0,%0" : : "r"(where) : "memory")

@@ -312,17 +353,12 @@

       if (lazy)

 	{

-	  /* The function descriptor of the appropriate trampline

-	     routine is used to set the 1st and 2nd doubleword of the

-	     plt_reserve.  */

-	  Elf64_FuncDesc *resolve_fd;

 	  Elf64_Word glink_offset;

-	  /* the plt_reserve area is the 1st 3 doublewords of the PLT */

-	  Elf64_FuncDesc *plt_reserve = (Elf64_FuncDesc *) plt;

 	  Elf64_Word offset;

+	  Elf64_Addr dlrr;

-	  resolve_fd = (Elf64_FuncDesc *) (profile ? _dl_profile_resolve

-					   : _dl_runtime_resolve);

+	  dlrr = (Elf64_Addr) (profile ? _dl_profile_resolve

+				       : _dl_runtime_resolve);

 	  if (profile && GLRO(dl_profile) != NULL

 	      && _dl_name_match_p (GLRO(dl_profile), map))

 	    /* This is the object we are looking for.  Say that we really

@@ -330,20 +366,33 @@

 	    GL(dl_profile_map) = map;

+#if _CALL_ELF != 2

 	  /* We need to stuff the address/TOC of _dl_runtime_resolve

 	     into doublewords 0 and 1 of plt_reserve.  Then we need to

 	     stuff the map address into doubleword 2 of plt_reserve.

 	     This allows the GLINK0 code to transfer control to the

 	     correct trampoline which will transfer control to fixup

 	     in dl-machine.c.  */

-	  plt_reserve->fd_func = resolve_fd->fd_func;

-	  plt_reserve->fd_toc  = resolve_fd->fd_toc;

-	  plt_reserve->fd_aux  = (Elf64_Addr) map;

+	  {

+	    /* The plt_reserve area is the 1st 3 doublewords of the PLT.  */

+	    Elf64_FuncDesc *plt_reserve = (Elf64_FuncDesc *) plt;

+	    Elf64_FuncDesc *resolve_fd = (Elf64_FuncDesc *) dlrr;

+	    plt_reserve->fd_func = resolve_fd->fd_func;

+	    plt_reserve->fd_toc  = resolve_fd->fd_toc;

+	    plt_reserve->fd_aux  = (Elf64_Addr) map;

 #ifdef RTLD_BOOTSTRAP

-	  /* When we're bootstrapping, the opd entry will not have

-	     been relocated yet.  */

-	  plt_reserve->fd_func += l_addr;

-	  plt_reserve->fd_toc  += l_addr;

+	    /* When we're bootstrapping, the opd entry will not have

+	       been relocated yet.  */

+	    plt_reserve->fd_func += l_addr;

+	    plt_reserve->fd_toc  += l_addr;

+#endif

+	  }

+#else

+	  /* When we don't have function descriptors, the first doubleword

+	     of the PLT holds the address of _dl_runtime_resolve, and the

+	     second doubleword holds the map address.  */

+	  plt[0] = dlrr;

+	  plt[1] = (Elf64_Addr) map;

 #endif

 	  /* Set up the lazy PLT entries.  */

@@ -354,14 +403,8 @@

 	    {

 	      plt[offset] = (Elf64_Xword) &glink[glink_offset];

-	      offset += 3;

-	      /* The first 32k entries of glink can set an index and

-		 branch using two instructions;  Past that point,

-		 glink uses three instructions.  */

-	      if (i < 0x8000)

-		glink_offset += 2;

-	      else

-		glink_offset += 3;

+	      offset += PLT_ENTRY_WORDS;

+	      glink_offset += GLINK_ENTRY_WORDS (i);

 	    }

 	  /* Now, we've modified data.  We need to write the changes from

@@ -389,6 +432,7 @@

 		       const Elf64_Rela *reloc,

 		       Elf64_Addr *reloc_addr, Elf64_Addr finaladdr)

 {

+#if _CALL_ELF != 2

   Elf64_FuncDesc *plt = (Elf64_FuncDesc *) reloc_addr;

   Elf64_FuncDesc *rel = (Elf64_FuncDesc *) finaladdr;

   Elf64_Addr offset = 0;

@@ -426,6 +470,9 @@

   plt->fd_func = rel->fd_func + offset;

   PPC_DCBST (&plt->fd_func);

   PPC_ISYNC;

+#else

+  *reloc_addr = finaladdr;

+#endif

   return finaladdr;

 }

@@ -433,6 +480,7 @@

 static inline void __attribute__ ((always_inline))

 elf_machine_plt_conflict (Elf64_Addr *reloc_addr, Elf64_Addr finaladdr)

 {

+#if _CALL_ELF != 2

   Elf64_FuncDesc *plt = (Elf64_FuncDesc *) reloc_addr;

   Elf64_FuncDesc *rel = (Elf64_FuncDesc *) finaladdr;

@@ -443,6 +491,9 @@

   PPC_DCBST (&plt->fd_aux);

   PPC_DCBST (&plt->fd_toc);

   PPC_SYNC;

+#else

+  *reloc_addr = finaladdr;

+#endif

 }

 /* Return the final value of a plt relocation.  */

@@ -512,6 +563,7 @@

 resolve_ifunc (Elf64_Addr value,

 	       const struct link_map *map, const struct link_map *sym_map)

 {

+#if _CALL_ELF != 2

 #ifndef RESOLVE_CONFLICT_FIND_MAP

   /* The function we are calling may not yet have its opd entry relocated.  */

   Elf64_FuncDesc opd;

@@ -529,6 +581,7 @@

       value = (Elf64_Addr) &opd;

     }

 #endif

+#endif

   return ((Elf64_Addr (*) (unsigned long int)) value) (GLRO(dl_hwcap));

 }

diff -urN glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/setjmp-common.S glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/setjmp-common.S

--- glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/setjmp-common.S	2014-05-29 13:58:25.000000000 -0500

+++ glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/setjmp-common.S	2014-05-29 14:00:27.000000000 -0500

@@ -55,21 +55,22 @@

    that saves r2 since the call won't go via a plt call stub.  See

    bugz #269.  __GI__setjmp is used in csu/libc-start.c when

    HAVE_CLEANUP_JMP_BUF is defined.  */

-ENTRY (BP_SYM (__GI__setjmp))

+ENTRY (__GI__setjmp)

 	std r2,40(r1)		/* Save the callers TOC in the save area.  */

-	cfi_endproc

-END_2 (BP_SYM (__GI__setjmp))

-/* Fall thru. */

+	CALL_MCOUNT 1

+	li r4,0			/* Set second argument to 0.  */

+	b JUMPTARGET (GLUE(__sigsetjmp,_ent))

+END (__GI__setjmp)

 #endif

-ENTRY (BP_SYM (_setjmp))

+ENTRY (_setjmp)

 	CALL_MCOUNT 1

 	li r4,0			/* Set second argument to 0.  */

 	b JUMPTARGET (GLUE(__sigsetjmp,_ent))

-END (BP_SYM (_setjmp))

+END (_setjmp)

 libc_hidden_def (_setjmp)

-ENTRY (BP_SYM (__sigsetjmp))

+ENTRY (__sigsetjmp)

 	CALL_MCOUNT 2

 JUMPTARGET(GLUE(__sigsetjmp,_ent)):

 	CHECK_BOUNDS_BOTH_WIDE_LIT (r3, r8, r9, JB_SIZE)

@@ -215,18 +216,18 @@

 	li	r3,0

 	blr

 #elif defined SHARED

-	b	JUMPTARGET (BP_SYM (__sigjmp_save))

+	b	JUMPTARGET (__sigjmp_save)

 #else

 	mflr	r0

 	std	r0,16(r1)

 	stdu	r1,-112(r1)

 	cfi_adjust_cfa_offset(112)

 	cfi_offset(lr,16)

-	bl	JUMPTARGET (BP_SYM (__sigjmp_save))

+	bl	JUMPTARGET (__sigjmp_save)

 	nop

 	ld	r0,112+16(r1)

 	addi	r1,r1,112

 	mtlr	r0

 	blr

 #endif

-END (BP_SYM (__sigsetjmp))

+END (__sigsetjmp)

diff -urN glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/sysdep.h glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/sysdep.h

--- glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/sysdep.h	2014-05-29 13:58:25.000000000 -0500

+++ glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/sysdep.h	2014-05-29 13:58:25.000000000 -0500

@@ -74,6 +74,8 @@

 #endif

 	.endm

+#if _CALL_ELF != 2

+

 /* Macro to prepare for calling via a function pointer.  */

 	.macro PPC64_LOAD_FUNCPTR PTR

 	ld      r12,0(\PTR)

@@ -115,13 +117,37 @@

 	.size name,.-BODY_LABEL(name);		\

 	.size BODY_LABEL(name),.-BODY_LABEL(name);

 #endif

+#define LOCALENTRY(name)

+

+#else /* _CALL_ELF */

+

+/* Macro to prepare for calling via a function pointer.  */

+	.macro PPC64_LOAD_FUNCPTR PTR

+	mr	r12,\PTR

+	mtctr   r12

+	.endm

+

+#define DOT_LABEL(X) X

+#define BODY_LABEL(X) X

+#define ENTRY_2(name)	\

+	.globl name;				\

+	.type name,@function;

+#define END_2(name)	\

+	.size name,.-name;

+#define LOCALENTRY(name)	\

+1:      addis	r2,r12,.TOC.-1b@ha; \

+        addi	r2,r2,.TOC.-1b@l; \

+	.localentry name,.-name;

+

+#endif /* _CALL_ELF */

 #define ENTRY(name)	\

 	.section	".text";		\

 	ENTRY_2(name)				\

 	.align ALIGNARG(2);			\

 BODY_LABEL(name):				\

-	cfi_startproc;

+	cfi_startproc;				\

+	LOCALENTRY(name)

 #define EALIGN_W_0  /* No words to insert.  */

 #define EALIGN_W_1  nop

@@ -140,7 +166,8 @@

 	.align ALIGNARG(alignt);		\

 	EALIGN_W_##words;			\

 BODY_LABEL(name):				\

-	cfi_startproc;

+	cfi_startproc;				\

+	LOCALENTRY(name)

 /* Local labels stripped out by the linker.  */

 #undef L

@@ -295,6 +322,8 @@

 #else /* !__ASSEMBLER__ */

+#if _CALL_ELF != 2

+

 #define PPC64_LOAD_FUNCPTR(ptr) \

 	"ld 	12,0(" #ptr ");\n"					\

 	"ld	2,8(" #ptr ");\n"					\

@@ -335,5 +364,26 @@

 	".size " #name ",.-" BODY_PREFIX #name ";\n"			\

 	".size " BODY_PREFIX #name ",.-" BODY_PREFIX #name ";"

 #endif

+#define LOCALENTRY(name)

+

+#else /* _CALL_ELF */

+

+#define PPC64_LOAD_FUNCPTR(ptr) \

+	"mr	12," #ptr ";\n"						\

+	"mtctr 	12;"

+

+#define DOT_PREFIX ""

+#define BODY_PREFIX ""

+#define ENTRY_2(name)	\

+	".type " #name ",@function;\n"					\

+	".globl " #name ";"

+#define END_2(name)	\

+	".size " #name ",.-" #name ";"

+#define LOCALENTRY(name)	\

+	"1: addis 2,12,.TOC.-1b@ha;\n"					\

+	"addi	2,2,.TOC.-1b@l;\n"					\

+	".localentry " #name ",.-" #name ";"

+

+#endif /* _CALL_ELF */

 #endif	/* __ASSEMBLER__ */

diff -urN glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/ldsodefs.h glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/ldsodefs.h

--- glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/ldsodefs.h	2014-05-29 13:58:24.000000000 -0500

+++ glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/ldsodefs.h	2014-05-29 13:58:25.000000000 -0500

@@ -23,6 +23,8 @@

 /* Now define our stuff.  */

+#if _CALL_ELF != 2

+

 static __always_inline bool

 _dl_ppc64_is_opd_sym (const struct link_map *l, const ElfW(Sym) *sym)

 {

@@ -73,4 +75,6 @@

 #define DL_ADDR_SYM_MATCH(L, SYM, MATCHSYM, ADDR) \

   _dl_ppc64_addr_sym_match (L, SYM, MATCHSYM, ADDR)

+#endif

+

 #endif /* ldsodefs.h */

diff -urN glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S

--- glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S	2014-05-29 13:58:24.000000000 -0500

+++ glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S	2014-05-29 13:58:25.000000000 -0500

@@ -111,6 +111,7 @@

 L(noparms):

+#if _CALL_ELF != 2

   /* Load the function address and TOC from the function descriptor

      and store them in the ucontext as NIP and r2.  Store the 3rd

      field of the function descriptor into the ucontext as r11 in case

@@ -121,6 +122,12 @@

   std   r0,(SIGCONTEXT_GP_REGS+(PT_NIP*8))(r3)

   std   r10,(SIGCONTEXT_GP_REGS+(PT_R2*8))(r3)

   std   r9,(SIGCONTEXT_GP_REGS+(PT_R11*8))(r3)

+#else

+  /* In the ELFv2 ABI, the function pointer is already the address.

+     Store it as NIP and r12 as required by the ABI.  */

+  std   r4,(SIGCONTEXT_GP_REGS+(PT_NIP*8))(r3)

+  std   r4,(SIGCONTEXT_GP_REGS+(PT_R12*8))(r3)

+#endif

   /* If the target function returns we need to do some cleanup.  We use a

      code trick to get the address of our cleanup function into the link