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-rw-r--r--sysdeps/alpha/dl-machine.h528
1 files changed, 528 insertions, 0 deletions
diff --git a/sysdeps/alpha/dl-machine.h b/sysdeps/alpha/dl-machine.h
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+++ b/sysdeps/alpha/dl-machine.h
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+/* Machine-dependent ELF dynamic relocation inline functions.  Alpha version.
+   Copyright (C) 1996-2014 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Richard Henderson <rth@tamu.edu>.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* This was written in the absence of an ABI -- don't expect
+   it to remain unchanged.  */
+
+#ifndef dl_machine_h
+#define dl_machine_h 1
+
+#define ELF_MACHINE_NAME "alpha"
+
+#include <string.h>
+
+
+/* Mask identifying addresses reserved for the user program,
+   where the dynamic linker should not map anything.  */
+#define ELF_MACHINE_USER_ADDRESS_MASK	0x120000000UL
+
+/* Translate a processor specific dynamic tag to the index in l_info array.  */
+#define DT_ALPHA(x) (DT_ALPHA_##x - DT_LOPROC + DT_NUM)
+
+/* Return nonzero iff ELF header is compatible with the running host.  */
+static inline int
+elf_machine_matches_host (const Elf64_Ehdr *ehdr)
+{
+  return ehdr->e_machine == EM_ALPHA;
+}
+
+/* Return the link-time address of _DYNAMIC.  The multiple-got-capable
+   linker no longer allocates the first .got entry for this.  But not to
+   worry, no special tricks are needed.  */
+static inline Elf64_Addr
+elf_machine_dynamic (void)
+{
+#ifndef NO_AXP_MULTI_GOT_LD
+  return (Elf64_Addr) &_DYNAMIC;
+#else
+  register Elf64_Addr *gp __asm__ ("$29");
+  return gp[-4096];
+#endif
+}
+
+/* Return the run-time load address of the shared object.  */
+
+static inline Elf64_Addr
+elf_machine_load_address (void)
+{
+  /* This relies on the compiler using gp-relative addresses for static symbols.  */
+  static void *dot = &dot;
+  return (void *)&dot - dot;
+}
+
+/* Set up the loaded object described by L so its unrelocated PLT
+   entries will jump to the on-demand fixup code in dl-runtime.c.  */
+
+static inline int
+elf_machine_runtime_setup (struct link_map *map, int lazy, int profile)
+{
+  extern char _dl_runtime_resolve_new[] attribute_hidden;
+  extern char _dl_runtime_profile_new[] attribute_hidden;
+  extern char _dl_runtime_resolve_old[] attribute_hidden;
+  extern char _dl_runtime_profile_old[] attribute_hidden;
+
+  struct pltgot {
+    char *resolve;
+    struct link_map *link;
+  };
+
+  struct pltgot *pg;
+  long secureplt;
+  char *resolve;
+
+  if (map->l_info[DT_JMPREL] == 0 || !lazy)
+    return lazy;
+
+  /* Check to see if we're using the read-only plt form.  */
+  secureplt = map->l_info[DT_ALPHA(PLTRO)] != 0;
+
+  /* If the binary uses the read-only secure plt format, PG points to
+     the .got.plt section, which is the right place for ld.so to place
+     its hooks.  Otherwise, PG is currently pointing at the start of
+     the plt; the hooks go at offset 16.  */
+  pg = (struct pltgot *) D_PTR (map, l_info[DT_PLTGOT]);
+  pg += !secureplt;
+
+  /* This function will be called to perform the relocation.  They're
+     not declared as functions to convince the compiler to use gp
+     relative relocations for them.  */
+  if (secureplt)
+    resolve = _dl_runtime_resolve_new;
+  else
+    resolve = _dl_runtime_resolve_old;
+
+  if (__builtin_expect (profile, 0))
+    {
+      if (secureplt)
+	resolve = _dl_runtime_profile_new;
+      else
+	resolve = _dl_runtime_profile_old;
+
+      if (GLRO(dl_profile) && _dl_name_match_p (GLRO(dl_profile), map))
+	{
+	  /* This is the object we are looking for.  Say that we really
+	     want profiling and the timers are started.  */
+	  GL(dl_profile_map) = map;
+	}
+    }
+
+  pg->resolve = resolve;
+  pg->link = map;
+
+  return lazy;
+}
+
+/* Initial entry point code for the dynamic linker.
+   The C function `_dl_start' is the real entry point;
+   its return value is the user program's entry point.  */
+
+#define RTLD_START asm ("\
+	.section .text						\n\
+	.set at							\n\
+	.globl _start						\n\
+	.ent _start						\n\
+_start:								\n\
+	.frame $31,0,$31,0					\n\
+	br	$gp, 0f						\n\
+0:	ldgp	$gp, 0($gp)					\n\
+	.prologue 0						\n\
+	/* Pass pointer to argument block to _dl_start.  */	\n\
+	mov	$sp, $16					\n\
+	bsr	$26, _dl_start		!samegp			\n\
+	.end _start						\n\
+	/* FALLTHRU */						\n\
+	.globl _dl_start_user					\n\
+	.ent _dl_start_user					\n\
+_dl_start_user:							\n\
+	.frame $31,0,$31,0					\n\
+	.prologue 0						\n\
+	/* Save the user entry point address in s0.  */		\n\
+	mov	$0, $9						\n\
+	/* See if we were run as a command with the executable	\n\
+	   file name as an extra leading argument.  */		\n\
+	ldah	$1, _dl_skip_args($gp)	!gprelhigh		\n\
+	ldl	$1, _dl_skip_args($1)	!gprellow		\n\
+	bne	$1, $fixup_stack				\n\
+$fixup_stack_ret:						\n\
+	/* The special initializer gets called with the stack	\n\
+	   just as the application's entry point will see it;	\n\
+	   it can switch stacks if it moves these contents	\n\
+	   over.  */						\n\
+" RTLD_START_SPECIAL_INIT "					\n\
+	/* Call _dl_init(_dl_loaded, argc, argv, envp) to run	\n\
+	   initializers.  */					\n\
+	ldah	$16, _rtld_local($gp)	!gprelhigh		\n\
+	ldq	$16, _rtld_local($16)	!gprellow		\n\
+	ldq	$17, 0($sp)					\n\
+	lda	$18, 8($sp)					\n\
+	s8addq	$17, 8, $19					\n\
+	addq	$19, $18, $19					\n\
+	bsr	$26, _dl_init_internal	!samegp			\n\
+	/* Pass our finalizer function to the user in $0. */	\n\
+	ldah	$0, _dl_fini($gp)	!gprelhigh		\n\
+	lda	$0, _dl_fini($0)	!gprellow		\n\
+	/* Jump to the user's entry point.  */			\n\
+	mov	$9, $27						\n\
+	jmp	($9)						\n\
+$fixup_stack:							\n\
+	/* Adjust the stack pointer to skip _dl_skip_args words.\n\
+	   This involves copying everything down, since the	\n\
+	   stack pointer must always be 16-byte aligned.  */	\n\
+	ldah	$7, _dl_argv_internal($gp) !gprelhigh		\n\
+	ldq	$2, 0($sp)					\n\
+	ldq	$5, _dl_argv_internal($7) !gprellow		\n\
+	subq	$31, $1, $6					\n\
+	subq	$2, $1, $2					\n\
+	s8addq	$6, $5, $5					\n\
+	mov	$sp, $4						\n\
+	s8addq	$1, $sp, $3					\n\
+	stq	$2, 0($sp)					\n\
+	stq	$5, _dl_argv_internal($7) !gprellow		\n\
+	/* Copy down argv.  */					\n\
+0:	ldq	$5, 8($3)					\n\
+	addq	$4, 8, $4					\n\
+	addq	$3, 8, $3					\n\
+	stq	$5, 0($4)					\n\
+	bne	$5, 0b						\n\
+	/* Copy down envp.  */					\n\
+1:	ldq	$5, 8($3)					\n\
+	addq	$4, 8, $4					\n\
+	addq	$3, 8, $3					\n\
+	stq	$5, 0($4)					\n\
+	bne	$5, 1b						\n\
+	/* Copy down auxiliary table.  */			\n\
+2:	ldq	$5, 8($3)					\n\
+	ldq	$6, 16($3)					\n\
+	addq	$4, 16, $4					\n\
+	addq	$3, 16, $3					\n\
+	stq	$5, -8($4)					\n\
+	stq	$6, 0($4)					\n\
+	bne	$5, 2b						\n\
+	br	$fixup_stack_ret				\n\
+	.end _dl_start_user					\n\
+	.set noat						\n\
+.previous");
+
+#ifndef RTLD_START_SPECIAL_INIT
+#define RTLD_START_SPECIAL_INIT /* nothing */
+#endif
+
+/* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry
+   or TLS variables, so undefined references 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.
+   This is unused on Alpha.  */
+
+# define elf_machine_type_class(type)	\
+  (((type) == R_ALPHA_JMP_SLOT		\
+    || (type) == R_ALPHA_DTPMOD64	\
+    || (type) == R_ALPHA_DTPREL64	\
+    || (type) == R_ALPHA_TPREL64) * ELF_RTYPE_CLASS_PLT)
+
+/* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
+#define ELF_MACHINE_JMP_SLOT	 R_ALPHA_JMP_SLOT
+
+/* The alpha never uses Elf64_Rel relocations.  */
+#define ELF_MACHINE_NO_REL 1
+
+/* We define an initialization functions.  This is called very early in
+ *    _dl_sysdep_start.  */
+#define DL_PLATFORM_INIT dl_platform_init ()
+
+static inline void __attribute__ ((unused))
+dl_platform_init (void)
+{
+	if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0')
+	/* Avoid an empty string which would disturb us.  */
+		GLRO(dl_platform) = NULL;
+}
+
+/* Fix up the instructions of a PLT entry to invoke the function
+   rather than the dynamic linker.  */
+static inline Elf64_Addr
+elf_machine_fixup_plt (struct link_map *map, lookup_t t,
+		       const Elf64_Rela *reloc,
+		       Elf64_Addr *got_addr, Elf64_Addr value)
+{
+  const Elf64_Rela *rela_plt;
+  Elf64_Word *plte;
+  long int edisp;
+
+  /* Store the value we are going to load.  */
+  *got_addr = value;
+
+  /* If this binary uses the read-only secure plt format, we're done.  */
+  if (map->l_info[DT_ALPHA(PLTRO)])
+    return value;
+
+  /* Otherwise we have to modify the plt entry in place to do the branch.  */
+
+  /* Recover the PLT entry address by calculating reloc's index into the
+     .rela.plt, and finding that entry in the .plt.  */
+  rela_plt = (const Elf64_Rela *) D_PTR (map, l_info[DT_JMPREL]);
+  plte = (Elf64_Word *) (D_PTR (map, l_info[DT_PLTGOT]) + 32);
+  plte += 3 * (reloc - rela_plt);
+
+  /* Find the displacement from the plt entry to the function.  */
+  edisp = (long int) (value - (Elf64_Addr)&plte[3]) / 4;
+
+  if (edisp >= -0x100000 && edisp < 0x100000)
+    {
+      /* If we are in range, use br to perfect branch prediction and
+	 elide the dependency on the address load.  This case happens,
+	 e.g., when a shared library call is resolved to the same library.  */
+
+      int hi, lo;
+      hi = value - (Elf64_Addr)&plte[0];
+      lo = (short int) hi;
+      hi = (hi - lo) >> 16;
+
+      /* Emit "lda $27,lo($27)" */
+      plte[1] = 0x237b0000 | (lo & 0xffff);
+
+      /* Emit "br $31,function" */
+      plte[2] = 0xc3e00000 | (edisp & 0x1fffff);
+
+      /* Think about thread-safety -- the previous instructions must be
+	 committed to memory before the first is overwritten.  */
+      __asm__ __volatile__("wmb" : : : "memory");
+
+      /* Emit "ldah $27,hi($27)" */
+      plte[0] = 0x277b0000 | (hi & 0xffff);
+    }
+  else
+    {
+      /* Don't bother with the hint since we already know the hint is
+	 wrong.  Eliding it prevents the wrong page from getting pulled
+	 into the cache.  */
+
+      int hi, lo;
+      hi = (Elf64_Addr)got_addr - (Elf64_Addr)&plte[0];
+      lo = (short)hi;
+      hi = (hi - lo) >> 16;
+
+      /* Emit "ldq $27,lo($27)" */
+      plte[1] = 0xa77b0000 | (lo & 0xffff);
+
+      /* Emit "jmp $31,($27)" */
+      plte[2] = 0x6bfb0000;
+
+      /* Think about thread-safety -- the previous instructions must be
+	 committed to memory before the first is overwritten.  */
+      __asm__ __volatile__("wmb" : : : "memory");
+
+      /* Emit "ldah $27,hi($27)" */
+      plte[0] = 0x277b0000 | (hi & 0xffff);
+    }
+
+  /* At this point, if we've been doing runtime resolution, Icache is dirty.
+     This will be taken care of in _dl_runtime_resolve.  If instead we are
+     doing this as part of non-lazy startup relocation, that bit of code
+     hasn't made it into Icache yet, so there's nothing to clean up.  */
+
+  return value;
+}
+
+/* Return the final value of a plt relocation.  */
+static inline Elf64_Addr
+elf_machine_plt_value (struct link_map *map, const Elf64_Rela *reloc,
+		       Elf64_Addr value)
+{
+  return value + reloc->r_addend;
+}
+
+/* Names of the architecture-specific auditing callback functions.  */
+#define ARCH_LA_PLTENTER	alpha_gnu_pltenter
+#define ARCH_LA_PLTEXIT		alpha_gnu_pltexit
+
+#endif /* !dl_machine_h */
+
+#ifdef RESOLVE_MAP
+
+/* Perform the relocation specified by RELOC and SYM (which is fully resolved).
+   MAP is the object containing the reloc.  */
+auto inline void
+__attribute__ ((always_inline))
+elf_machine_rela (struct link_map *map,
+		  const Elf64_Rela *reloc,
+		  const Elf64_Sym *sym,
+		  const struct r_found_version *version,
+		  void *const reloc_addr_arg,
+		  int skip_ifunc)
+{
+  Elf64_Addr *const reloc_addr = reloc_addr_arg;
+  unsigned long int const r_type = ELF64_R_TYPE (reloc->r_info);
+
+#if !defined RTLD_BOOTSTRAP && !defined HAVE_Z_COMBRELOC && !defined SHARED
+  /* This is defined in rtld.c, but nowhere in the static libc.a; make the
+     reference weak so static programs can still link.  This declaration
+     cannot be done when compiling rtld.c (i.e.  #ifdef RTLD_BOOTSTRAP)
+     because rtld.c contains the common defn for _dl_rtld_map, which is
+     incompatible with a weak decl in the same file.  */
+  weak_extern (_dl_rtld_map);
+#endif
+
+  /* We cannot use a switch here because we cannot locate the switch
+     jump table until we've self-relocated.  */
+
+#if !defined RTLD_BOOTSTRAP || !defined HAVE_Z_COMBRELOC
+  if (__builtin_expect (r_type == R_ALPHA_RELATIVE, 0))
+    {
+# if !defined RTLD_BOOTSTRAP && !defined HAVE_Z_COMBRELOC
+      /* Already done in dynamic linker.  */
+      if (map != &GL(dl_rtld_map))
+# endif
+	{
+	  /* XXX Make some timings.  Maybe it's preferable to test for
+	     unaligned access and only do it the complex way if necessary.  */
+	  Elf64_Addr reloc_addr_val;
+
+	  /* Load value without causing unaligned trap. */
+	  memcpy (&reloc_addr_val, reloc_addr_arg, 8);
+	  reloc_addr_val += map->l_addr;
+
+	  /* Store value without causing unaligned trap. */
+	  memcpy (reloc_addr_arg, &reloc_addr_val, 8);
+	}
+    }
+  else
+#endif
+    if (__builtin_expect (r_type == R_ALPHA_NONE, 0))
+      return;
+  else
+    {
+      struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
+      Elf64_Addr sym_value;
+      Elf64_Addr sym_raw_value;
+
+      sym_raw_value = sym_value = reloc->r_addend;
+      if (sym_map)
+	{
+	  sym_raw_value += sym->st_value;
+	  sym_value = sym_raw_value + sym_map->l_addr;
+	}
+
+      if (r_type == R_ALPHA_GLOB_DAT)
+	*reloc_addr = sym_value;
+#ifdef RESOLVE_CONFLICT_FIND_MAP
+      /* In .gnu.conflict section, R_ALPHA_JMP_SLOT relocations have
+	 R_ALPHA_JMP_SLOT in lower 8 bits and the remaining 24 bits
+	 are .rela.plt index.  */
+      else if ((r_type & 0xff) == R_ALPHA_JMP_SLOT)
+	{
+	  /* elf_machine_fixup_plt needs the map reloc_addr points into,
+	     while in _dl_resolve_conflicts map is _dl_loaded.  */
+	  RESOLVE_CONFLICT_FIND_MAP (map, reloc_addr);
+	  reloc = ((const Elf64_Rela *) D_PTR (map, l_info[DT_JMPREL]))
+		  + (r_type >> 8);
+	  elf_machine_fixup_plt (map, 0, reloc, reloc_addr, sym_value);
+	}
+#else
+      else if (r_type == R_ALPHA_JMP_SLOT)
+	elf_machine_fixup_plt (map, 0, reloc, reloc_addr, sym_value);
+#endif
+#ifndef RTLD_BOOTSTRAP
+      else if (r_type == R_ALPHA_REFQUAD)
+	{
+	  /* Store value without causing unaligned trap.  */
+	  memcpy (reloc_addr_arg, &sym_value, 8);
+	}
+#endif
+      else if (r_type == R_ALPHA_DTPMOD64)
+	{
+# ifdef RTLD_BOOTSTRAP
+	  /* During startup the dynamic linker is always index 1.  */
+	  *reloc_addr = 1;
+# else
+	  /* Get the information from the link map returned by the
+	     resolv function.  */
+	  if (sym_map != NULL)
+	    *reloc_addr = sym_map->l_tls_modid;
+# endif
+	}
+      else if (r_type == R_ALPHA_DTPREL64)
+	{
+# ifndef RTLD_BOOTSTRAP
+	  /* During relocation all TLS symbols are defined and used.
+	     Therefore the offset is already correct.  */
+	  *reloc_addr = sym_raw_value;
+# endif
+	}
+      else if (r_type == R_ALPHA_TPREL64)
+	{
+# ifdef RTLD_BOOTSTRAP
+	  *reloc_addr = sym_raw_value + map->l_tls_offset;
+# else
+	  if (sym_map)
+	    {
+	      CHECK_STATIC_TLS (map, sym_map);
+	      *reloc_addr = sym_raw_value + sym_map->l_tls_offset;
+	    }
+# endif
+	}
+      else
+	_dl_reloc_bad_type (map, r_type, 0);
+    }
+}
+
+/* Let do-rel.h know that on Alpha if l_addr is 0, all RELATIVE relocs
+   can be skipped.  */
+#define ELF_MACHINE_REL_RELATIVE 1
+
+auto inline void
+__attribute__ ((always_inline))
+elf_machine_rela_relative (Elf64_Addr l_addr, const Elf64_Rela *reloc,
+			   void *const reloc_addr_arg)
+{
+  /* XXX Make some timings.  Maybe it's preferable to test for
+     unaligned access and only do it the complex way if necessary.  */
+  Elf64_Addr reloc_addr_val;
+
+  /* Load value without causing unaligned trap. */
+  memcpy (&reloc_addr_val, reloc_addr_arg, 8);
+  reloc_addr_val += l_addr;
+
+  /* Store value without causing unaligned trap. */
+  memcpy (reloc_addr_arg, &reloc_addr_val, 8);
+}
+
+auto inline void
+__attribute__ ((always_inline))
+elf_machine_lazy_rel (struct link_map *map,
+		      Elf64_Addr l_addr, const Elf64_Rela *reloc,
+		      int skip_ifunc)
+{
+  Elf64_Addr * const reloc_addr = (void *)(l_addr + reloc->r_offset);
+  unsigned long int const r_type = ELF64_R_TYPE (reloc->r_info);
+
+  if (r_type == R_ALPHA_JMP_SLOT)
+    {
+      /* Perform a RELATIVE reloc on the .got entry that transfers
+	 to the .plt.  */
+      *reloc_addr += l_addr;
+    }
+  else if (r_type == R_ALPHA_NONE)
+    return;
+  else
+    _dl_reloc_bad_type (map, r_type, 1);
+}
+
+#endif /* RESOLVE_MAP */