* sysdeps/alpha/dl-machine.h: New file. cvs/libc-960612

1 files changed, 373 insertions, 0 deletions

diff --git a/sysdeps/alpha/dl-machine.h b/sysdeps/alpha/dl-machine.h
new file mode 100644
index 0000000000..a92c319fc3
--- /dev/null
+++ b/sysdeps/alpha/dl-machine.h
@@ -0,0 +1,373 @@
+/* Machine-dependent ELF dynamic relocation inline functions.  Alpha version.
+Copyright (C) 1996 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+Contributed by Richard Henderson <rht@tamu.edu>.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+/* This was written in the absense of an ABI -- don't expect
+   it to remain unchanged.  */
+
+#define ELF_MACHINE_NAME "alpha"
+
+#include <assert.h>
+#include <string.h>
+#include <link.h>
+
+
+/* Return nonzero iff E_MACHINE is compatible with the running host.  */
+static inline int
+elf_machine_matches_host (Elf64_Word e_machine)
+{
+  return e_machine == EM_ALPHA;
+}
+
+
+/* Return the run-time address of the _GLOBAL_OFFSET_TABLE_.
+   Must be inlined in a function which uses global data.  */
+static inline Elf64_Addr *
+elf_machine_got (void)
+{
+  register Elf64_Addr gp __asm__("$29");
+  return (Elf64_Addr *)(gp - 0x8000);
+}
+
+
+/* Return the run-time load address of the shared object.  */
+static inline Elf64_Addr
+elf_machine_load_address (void)
+{
+  /* NOTE: While it is generally unfriendly to put data in the text
+     segment, it is only slightly less so when the "data" is an
+     instruction.  While we don't have to worry about GLD just yet, an
+     optimizing linker might decide that our "data" is an unreachable
+     instruction and throw it away -- with the right switches, DEC's
+     linker will do this.  What ought to happen is we should add
+     something to GAS to allow us access to the new GPREL_HI32/LO32
+     relocation types stolen from OSF/1 3.0.  */
+  /* This code relies on the fact that BRADDR relocations do not
+     appear in dynamic relocation tables.  Not that that would be very
+     useful anyway -- br/bsr has a 4MB range and the shared libraries
+     are usually many many terabytes away.  */
+
+  Elf64_Addr dot;
+  long zero_disp;
+
+  asm("br %0, 1f\n\t"
+      ".weak __load_address_undefined\n\t"
+      "br $0, __load_address_undefined\n"
+      "1:"
+      : "=r"(dot));
+
+  zero_disp = *(int *)dot;
+  zero_disp = (zero_disp << 43) >> 41;
+
+  return dot + 4 + zero_disp;
+}
+
+
+/* Fix up the instructions of a PLT entry to invoke the function
+   rather than the dynamic linker.  */
+static inline void
+elf_alpha_fix_plt(struct link_map *l,
+		  const Elf64_Rela *reloc,
+		  Elf64_Addr value)
+{
+  const Elf64_Rela *rela_plt;
+  Elf64_Word *plte;
+  long disp;
+
+  /* Recover the PLT entry address by calculating reloc's index into the
+     .rela.plt, and finding that entry in the .plt.  */
+
+  rela_plt = (void *)(l->l_addr + l->l_info[DT_JMPREL]->d_un.d_ptr);
+
+  plte = (void *)(l->l_addr + l->l_info[DT_PLTGOT]->d_un.d_ptr);
+  plte += 2*(reloc - rela_plt) + 8;
+
+  /* Find the displacement from the plt entry to the function.  */
+
+  disp = value - (Elf64_Addr)&plte[2];
+
+  /* Change "lda $27, ofs($31)" to "ldq $27, ofs($gp)" */
+  plte[0] = 0xa77d0000 | (plte[0] & 0xffff);
+
+  if (disp >= -0x100000 && disp < 0x100000)
+    {
+      /* If we are in range, use br to perfect branch prediction and
+	 elide the dependancy on the address load.  This case happens,
+	 e.g., when a shared library call is resolved to the same library.  */
+      /* Change "br $0, plt0" to "br $31,function" */
+      plte[1] = 0xc3e00000 | (disp & 0x1fffff);
+    }
+  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.  */
+      /* Change "br $0, plt0" to "jmp $31,($27)" */
+      plte[1] = 0x6bfb0000;
+    }
+
+  /* Flush the instruction cache now that we've diddled.   Tag it as
+     modifying memory to checkpoint memory writes during optimization.  */
+  asm volatile("call_pal 0x86" : : : "memory");
+}
+
+/* Perform the relocation specified by RELOC and SYM (which is fully resolved).
+   MAP is the object containing the reloc.  */
+static inline void
+elf_machine_rela (struct link_map *map,
+		  const Elf64_Rela *reloc,
+		  const Elf64_Sym *sym,
+		  Elf64_Addr (*resolve) (const Elf64_Sym **ref,
+					 Elf64_Addr reloc_addr,
+					 int noplt))
+{
+  Elf64_Addr *const reloc_addr = (void *)(map->l_addr + reloc->r_offset);
+  unsigned long r_info = ELF64_R_TYPE (reloc->r_info);
+
+  /* We cannot use a switch here because we cannot locate the switch
+     jump table until we've self-relocated.  */
+
+  if (r_info == R_ALPHA_RELATIVE)
+    {
+      /* Already done in dynamic linker.  */
+      if (!resolve || map != &_dl_rtld_map)
+	*reloc_addr += map->l_addr;
+    }
+  else if (r_info == R_ALPHA_NONE)
+    ;
+  else
+    {
+      Elf64_Addr loadbase, sym_value;
+
+      if (resolve)
+	{
+	  loadbase = (*resolve)(&sym, (Elf64_Addr)reloc_addr,
+			        r_info == R_ALPHA_JMP_SLOT);
+	}
+      else
+	loadbase = map->l_addr;
+
+      sym_value = sym ? loadbase + sym->st_value : 0;
+
+      if (r_info == R_ALPHA_GLOB_DAT)
+	{
+	  *reloc_addr = sym_value;
+	}
+      else if (r_info == R_ALPHA_JMP_SLOT)
+	{
+	  *reloc_addr = sym_value;
+	  elf_alpha_fix_plt(map, reloc, sym_value);
+	}
+      else if (r_info == R_ALPHA_REFQUAD)
+	{
+	  sym_value += *reloc_addr;
+	  if (resolve && map == &_dl_rtld_map)
+	    {
+	      /* Undo the relocation done here during bootstrapping.
+		 Now we will relocate anew, possibly using a binding
+		 found in the user program or a loaded library rather
+		 than the dynamic linker's built-in definitions used
+		 while loading those libraries.  */
+	      const Elf64_Sym *const dlsymtab
+		= (void *)(map->l_addr + map->l_info[DT_SYMTAB]->d_un.d_ptr);
+	      sym_value -= map->l_addr;
+	      sym_value -= dlsymtab[ELF64_R_SYM(reloc->r_info)].st_value;
+	    }
+	  else
+	    sym_value += reloc->r_addend;
+	  *reloc_addr = sym_value;
+	}
+      else if (r_info == R_ALPHA_COPY)
+	memcpy (reloc_addr, (void *) sym_value, sym->st_size);
+      else
+	assert (! "unexpected dynamic reloc type");
+    }
+}
+
+static inline void
+elf_machine_lazy_rel (struct link_map *map, const Elf64_Rela *reloc)
+{
+  Elf64_Addr *const reloc_addr = (void *)(map->l_addr + reloc->r_offset);
+  unsigned long r_info = ELF64_R_TYPE (reloc->r_info);
+
+  if (r_info == R_ALPHA_JMP_SLOT)
+    {
+      /* Perform a RELATIVE reloc on the .got entry that transfers
+	 to the .plt.  */
+      *reloc_addr += map->l_addr;
+    }
+  else if (r_info == R_ALPHA_NONE)
+    ;
+  else
+    assert (! "unexpected PLT reloc type");
+}
+
+/* The alpha never uses Elf_Rel relocations.  */
+#define ELF_MACHINE_NO_REL 1
+
+
+/* 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 void
+elf_machine_runtime_setup (struct link_map *l, int lazy)
+{
+  Elf64_Addr plt;
+  extern void _dl_runtime_resolve (void);
+
+  if (l->l_info[DT_JMPREL] && lazy)
+    {
+      /* The GOT entries for the functions in the PLT have not been
+	 filled in yet.  Their initial contents are directed to the
+	 PLT which arranges for the dynamic linker to be called.  */
+      plt = l->l_addr + l->l_info[DT_PLTGOT]->d_un.d_ptr;
+
+      /* This function will be called to perform the relocation.  */
+      *(Elf64_Addr *)(plt + 16) = (Elf64_Addr) &_dl_runtime_resolve;
+
+      /* Identify this shared object */
+      *(Elf64_Addr *)(plt + 24) = (Elf64_Addr) l;
+    }
+}
+
+/* This code is used in dl-runtime.c to call the `fixup' function
+   and then redirect to the address it returns.  */
+#define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ( \
+"/* Trampoline for _dl_runtime_resolver */
+	.globl _dl_runtime_resolve
+	.ent _dl_runtime_resolve
+_dl_runtime_resolve:
+	lda	$sp, -168($sp)
+	.frame	$sp, 168, $26
+	/* Preserve all registers that C normally doesn't.  */
+	stq	$26, 0($sp)
+	stq	$0, 8($sp)
+	stq	$1, 16($sp)
+	stq	$2, 24($sp)
+	stq	$3, 32($sp)
+	stq	$4, 40($sp)
+	stq	$5, 48($sp)
+	stq	$6, 56($sp)
+	stq	$7, 64($sp)
+	stq	$8, 72($sp)
+	stq	$16, 80($sp)
+	stq	$17, 88($sp)
+	stq	$18, 96($sp)
+	stq	$19, 104($sp)
+	stq	$20, 112($sp)
+	stq	$21, 120($sp)
+	stq	$22, 128($sp)
+	stq	$23, 136($sp)
+	stq	$24, 144($sp)
+	stq	$25, 152($sp)
+	stq	$29, 160($sp)
+	.mask	0x27ff01ff, -168
+	/* Set up our $gp */
+	br	$gp, .+4
+	ldgp	$gp, 0($gp)
+	.prologue 1
+	/* Set up the arguments for _dl_runtime_resolve. */
+	/* $16 = link_map out of plt0 */
+	ldq	$16, 8($27)
+	/* $17 = (($0 - 8) - ($1 + 16)) / 8 * sizeof(Elf_Rela) */
+	subq	$28, $27, $28
+	subq	$28, 24, $28
+	addq	$28, $28, $17
+	addq	$28, $17, $17
+	/* Do the fixup */
+	bsr	$26, fixup..ng
+	/* Move the destination address to a safe place.  */
+	mov	$0, $27
+	/* Restore program registers.  */
+	ldq	$26, 0($sp)
+	ldq	$0, 8($sp)
+	ldq	$1, 16($sp)
+	ldq	$2, 24($sp)
+	ldq	$3, 32($sp)
+	ldq	$4, 40($sp)
+	ldq	$5, 48($sp)
+	ldq	$6, 56($sp)
+	ldq	$7, 64($sp)
+	ldq	$8, 72($sp)
+	ldq	$16, 80($sp)
+	ldq	$17, 88($sp)
+	ldq	$18, 96($sp)
+	ldq	$19, 104($sp)
+	ldq	$20, 112($sp)
+	ldq	$21, 120($sp)
+	ldq	$22, 128($sp)
+	ldq	$23, 136($sp)
+	ldq	$24, 144($sp)
+	ldq	$25, 152($sp)
+	ldq	$29, 160($sp)
+	/* Clean up and turn control to the destination */
+	lda	$sp, 168($sp)
+	jmp	$31, ($27)
+	.end _dl_runtime_resolve");
+
+/* The PLT uses Elf_Rel relocs.  */
+#define elf_machine_relplt elf_machine_rela
+
+/* Mask identifying addresses reserved for the user program,
+   where the dynamic linker should not map anything.  */
+/* FIXME */
+#define ELF_MACHINE_USER_ADDRESS_MASK	(~0x1FFFFFFFFUL)
+
+/* 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 ("\
+.text
+	.globl _start
+	.globl _dl_start_user
+_start:
+	br	$gp,.+4
+	ldgp	$gp, 0($gp)
+	/* Pass pointer to argument block to _dl_start.  */
+	mov	$sp, $16
+	bsr	$26, _dl_start..ng
+_dl_start_user:
+	/* Save the user entry point address in s0.  */
+	mov	$0, $9
+	/* See if we were run as a command with the executable file
+	   name as an extra leading argument.  If so, adjust the stack
+	   pointer to skip _dl_skip_args words.  */
+	ldl	$1, _dl_skip_args
+	beq	$1, 0f
+	ldq	$2, 0($sp)
+	subq	$2, $1, $2
+	s8addq	$1, $sp, $sp
+	stq	$2, 0($sp)
+	/* Load _dl_default_scope[2] into s1 to pass to _dl_init_next.  */
+0:	ldq	$10, _dl_default_scope+16
+	/* Call _dl_init_next to return the address of an initalizer
+	   function to run.  */
+1:	mov	$10, $16
+	jsr	$26, _dl_init_next
+	ldgp	$gp, 0($26)
+	beq	$0, 2f
+	mov	$0, $27
+	jsr	$26, ($0)
+	ldgp	$gp, 0($26)
+	br	1b
+2:	/* Pass our finalizer function to the user in $0. */
+	lda	$0, _dl_fini
+	/* Jump to the user's entry point.  */
+	jmp	($9)");