rtld: Add FDPIC code for arm

	Add FDPIC dynamic relocations support, similar to what other FDPIC
	targets do.

	Lazy binding is implemented in a folllow-up patch.

	Disable the SEND* macros because they involve relocations to
	access constant strings that are unsupported by the existing
	arm version.

	Define DL_START, START, ARCH_NEEDS_BOOTSTRAP_RELOCS,
	DL_CHECK_LIB_TYPE similarly to what other FDPIC targets do.

	Define raise() because _dl_find_hash references __aeabi_uidivmod,
	which uses __aeabi_idiv0 which in turn references raise.

	* include/elf.h (R_ARM_FUNCDESC): Define.
	(R_ARM_FUNCDESC_VALUE): Define.
	* ldso/include/dl-string.h (SEND_STDERR, SEND_ADDRESS_STDERR)
	(SEND_NUMBER_STDERR): Define empty for __FDPIC__.
	* ldso/ldso/arm/dl-inlines.h: New file.
	* ldso/ldso/arm/dl-startup.h (PERFORM_BOOTSTRAP_RELOC): Fix type
	of load_addr. Fix handling of R_ARM_RELATIVE, add support for
	R_ARM_FUNCDESC_VALUE.
	(DL_START, START): Define for __FDPIC__.
	(raise): Define.
	* ldso/ldso/arm/dl-sysdep.h (ARCH_NEEDS_BOOTSTRAP_RELOCS): Define.
	(DL_CHECK_LIB_TYPE): Define.
	(elf_machine_type_class): Take into account FDPIC related
	relocations.
	(elf_machine_load_address): Support __FDPIC__.
	(elf_machine_relative): Likewise.
	* ldso/ldso/arm/elfinterp.c (_dl_linux_resolver): Dummy support
	for __FDPIC__, implemented in a later patch.
	(_dl_do_reloc): Fix reloc_adr computation for __FDPIC__, fix
	handling of local symbols. Fix handling of R_ARM_RELATIVE, add
	support for R_ARM_FUNCDESC_VALUE, R_ARM_FUNCDESC.
	* ldso/ldso/arm/resolve.S: Make _dl_linux_resolve hidden.
	* ldso/ldso/fdpic/dl-inlines.h (htab_delete): Declare.
	* libc/sysdeps/linux/arm/bits/elf-fdpic.h: New file, similar to bfin's.
	* libc/sysdeps/linux/arm/crtreloc.c: Likewise.
	* libc/sysdeps/linux/arm/find_exidx.c (__dl_addr_in_loadaddr) Define.
	(find_exidx_callback): Support __FDPIC__.

Signed-off-by: Mickaël Guêné <mickael.guene@st.com>
Signed-off-by: Christophe Lyon <christophe.lyon@st.com>

3 files changed, 296 insertions, 0 deletions

diff --git a/libc/sysdeps/linux/arm/bits/elf-fdpic.h b/libc/sysdeps/linux/arm/bits/elf-fdpic.h
new file mode 100644
index 000000000..3d6db54af
--- /dev/null
+++ b/libc/sysdeps/linux/arm/bits/elf-fdpic.h
@@ -0,0 +1,114 @@
+/* Copyright 2003, 2004 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+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.
+
+In addition to the permissions in the GNU Lesser General Public
+License, the Free Software Foundation gives you unlimited
+permission to link the compiled version of this file with other
+programs, and to distribute those programs without any restriction
+coming from the use of this file.  (The GNU Lesser General Public
+License restrictions do apply in other respects; for example, they
+cover modification of the file, and distribution when not linked
+into another program.)
+
+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 Lesser General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef _BITS_ELF_FDPIC_H
+#define _BITS_ELF_FDPIC_H
+
+/* These data structures are described in the FDPIC ABI extension.
+   The kernel passes a process a memory map, such that for every LOAD
+   segment there is an elf32_fdpic_loadseg entry.  A pointer to an
+   elf32_fdpic_loadmap is passed in r7 at start-up, and a pointer to
+   an additional such map is passed in r8 for the interpreter, when
+   there is one.  */
+
+#include <elf.h>
+
+/* This data structure represents a PT_LOAD segment.  */
+struct elf32_fdpic_loadseg
+{
+  /* Core address to which the segment is mapped.  */
+  Elf32_Addr addr;
+  /* VMA recorded in the program header.  */
+  Elf32_Addr p_vaddr;
+  /* Size of this segment in memory.  */
+  Elf32_Word p_memsz;
+};
+
+struct elf32_fdpic_loadmap {
+  /* Protocol version number, must be zero.  */
+  Elf32_Half version;
+  /* Number of segments in this map.  */
+  Elf32_Half nsegs;
+  /* The actual memory map.  */
+  struct elf32_fdpic_loadseg segs[/*nsegs*/];
+};
+
+struct elf32_fdpic_loadaddr {
+  struct elf32_fdpic_loadmap *map;
+  void *got_value;
+};
+
+/* Map a pointer's VMA to its corresponding address according to the
+   load map.  */
+static __always_inline void *
+__reloc_pointer (void *p,
+		 const struct elf32_fdpic_loadmap *map)
+{
+  int c;
+
+#if 0
+  if (map->version != 0)
+    /* Crash.  */
+    ((void(*)())0)();
+#endif
+
+  /* No special provision is made for NULL.  We don't want NULL
+     addresses to go through relocation, so they shouldn't be in
+     .rofixup sections, and, if they're present in dynamic
+     relocations, they shall be mapped to the NULL address without
+     undergoing relocations.  */
+
+  for (c = 0;
+       /* Take advantage of the fact that the loadmap is ordered by
+	  virtual addresses.  In general there will only be 2 entries,
+	  so it's not profitable to do a binary search.  */
+       c < map->nsegs && p >= (void*)map->segs[c].p_vaddr;
+       c++)
+    {
+      /* This should be computed as part of the pointer comparison
+	 above, but we want to use the carry in the comparison, so we
+	 can't convert it to an integer type beforehand.  */
+      unsigned long offset = p - (void*)map->segs[c].p_vaddr;
+      /* We only check for one-past-the-end for the last segment,
+	 assumed to be the data segment, because other cases are
+	 ambiguous in the absence of padding between segments, and
+	 rofixup already serves as padding between text and data.
+	 Unfortunately, unless we special-case the last segment, we
+	 fail to relocate the _end symbol.  */
+      if (offset < map->segs[c].p_memsz
+	  || (offset == map->segs[c].p_memsz && c + 1 == map->nsegs))
+	return (char*)map->segs[c].addr + offset;
+    }
+
+  /* We might want to crash instead.  */
+  return (void*)-1;
+}
+
+# define __RELOC_POINTER(ptr, loadaddr) \
+  (__reloc_pointer ((void*)(ptr), \
+		    (loadaddr).map))
+
+#endif /* _BITS_ELF_FDPIC_H */
diff --git a/libc/sysdeps/linux/arm/crtreloc.c b/libc/sysdeps/linux/arm/crtreloc.c
new file mode 100644
index 000000000..560b4168b
--- /dev/null
+++ b/libc/sysdeps/linux/arm/crtreloc.c
@@ -0,0 +1,144 @@
+/* Copyright (C) 2003, 2004 Free Software Foundation, Inc.
+   written by Alexandre Oliva <aoliva@redhat.com>
+This file is part of the GNU C Library.
+
+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.
+
+In addition to the permissions in the GNU Lesser General Public
+License, the Free Software Foundation gives you unlimited
+permission to link the compiled version of this file with other
+programs, and to distribute those programs without any restriction
+coming from the use of this file.  (The GNU Lesser General Public
+License restrictions do apply in other respects; for example, they
+cover modification of the file, and distribution when not linked
+into another program.)
+
+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 Lesser General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, see <http://www.gnu.org/licenses/>.  */
+
+#ifdef __FDPIC__
+
+#include <sys/types.h>
+#include <link.h>
+
+/* This file is to be compiled into crt object files, to enable
+   executables to easily self-relocate.  */
+
+union word {
+    char c[4];
+    void *v;
+};
+
+/* Compute the runtime address of pointer in the range [p,e), and then
+   map the pointer pointed by it.  */
+static __always_inline void ***
+reloc_range_indirect (void ***p, void ***e,
+		      const struct elf32_fdpic_loadmap *map)
+{
+  while (p < e)
+    {
+      if (*p != (void **)-1)
+	{
+	  void *ptr = __reloc_pointer (*p, map);
+	  if (ptr != (void *)-1)
+	    {
+	      void *pt;
+	      if ((long)ptr & 3)
+		{
+		  unsigned char *c = ptr;
+		  int i;
+		  unsigned long v = 0;
+		  for (i = 0; i < 4; i++)
+		    v |= c[i] << 8 * i;
+		  pt = (void *)v;
+		}
+	      else
+		pt = *(void**)ptr;
+	      pt = __reloc_pointer (pt, map);
+	      if ((long)ptr & 3)
+		{
+		  unsigned char *c = ptr;
+		  int i;
+		  unsigned long v = (unsigned long)pt;
+		  for (i = 0; i < 4; i++, v >>= 8)
+		    c[i] = v;
+		}
+	      else
+		*(void**)ptr = pt;
+	    }
+	}
+      p++;
+    }
+  return p;
+}
+
+/* Call __reloc_range_indirect for the given range except for the last
+   entry, whose contents are only relocated.  It's expected to hold
+   the GOT value.  */
+attribute_hidden void*
+__self_reloc (const struct elf32_fdpic_loadmap *map,
+	      void ***p, void ***e)
+{
+  p = reloc_range_indirect (p, e-1, map);
+
+  if (p >= e)
+    return (void*)-1;
+
+  return __reloc_pointer (*p, map);
+}
+
+#if 0
+/* These are other functions that might be useful, but that we don't
+   need.  */
+
+/* Remap pointers in [p,e).  */
+static __always_inline void**
+reloc_range (void **p, void **e,
+	     const struct elf32_fdpic_loadmap *map)
+{
+  while (p < e)
+    {
+      *p = __reloc_pointer (*p, map);
+      p++;
+    }
+  return p;
+}
+
+/* Remap p, adjust e by the same offset, then map the pointers in the
+   range determined by them.  */
+void attribute_hidden
+__reloc_range (const struct elf32_fdpic_loadmap *map,
+	       void **p, void **e)
+{
+  void **old = p;
+
+  p = __reloc_pointer (p, map);
+  e += p - old;
+  reloc_range (p, e, map);
+}
+
+/* Remap p, adjust e by the same offset, then map pointers referenced
+   by the (unadjusted) pointers in the range.  Return the relocated
+   value of the last pointer in the range.  */
+void* attribute_hidden
+__reloc_range_indirect (const struct elf32_fdpic_loadmap *map,
+			void ***p, void ***e)
+{
+  void ***old = p;
+
+  p = __reloc_pointer (p, map);
+  e += p - old;
+  return reloc_range_indirect (p, e, map);
+}
+#endif
+
+#endif /* __FDPIC__ */
diff --git a/libc/sysdeps/linux/arm/find_exidx.c b/libc/sysdeps/linux/arm/find_exidx.c
index 679d90c05..cd4d442cf 100644
--- a/libc/sysdeps/linux/arm/find_exidx.c
+++ b/libc/sysdeps/linux/arm/find_exidx.c
@@ -18,6 +18,23 @@
 #include <link.h>
 #include <unwind.h>
 
+#if __FDPIC__
+#include <bits/elf-fdpic.h>
+static __always_inline int
+__dl_addr_in_loadaddr(void *p, struct elf32_fdpic_loadaddr loadaddr)
+{
+ struct elf32_fdpic_loadmap *map = loadaddr.map;
+ int c;
+
+ for (c = 0; c < map->nsegs; c++)
+   if ((void *)map->segs[c].addr <= p &&
+       (char *)p < (char *)map->segs[c].addr + map->segs[c].p_memsz)
+     return 1;
+
+ return 0;
+}
+#endif
+
 struct unw_eh_callback_data
 {
   _Unwind_Ptr pc;
@@ -32,6 +49,26 @@ struct unw_eh_callback_data
 static int
 find_exidx_callback (struct dl_phdr_info * info, size_t size, void * ptr)
 {
+#if __FDPIC__
+  struct unw_eh_callback_data * data;
+  const ElfW(Phdr) *phdr;
+  int i;
+  int match = 0;
+
+  data = (struct unw_eh_callback_data *) ptr;
+  if (__dl_addr_in_loadaddr((void *) data->pc, info->dlpi_addr)) {
+    match = 1;
+    phdr = info->dlpi_phdr;
+    for (i = info->dlpi_phnum; i > 0; i--, phdr++) {
+      if (phdr->p_type == PT_ARM_EXIDX) {
+        data->exidx_start = (_Unwind_Ptr) __RELOC_POINTER(phdr->p_vaddr, info->dlpi_addr);
+        data->exidx_len = phdr->p_memsz;
+      }
+    }
+  }
+
+  return match;
+#else
   struct unw_eh_callback_data * data;
   const ElfW(Phdr) *phdr;
   int i;
@@ -59,6 +96,7 @@ find_exidx_callback (struct dl_phdr_info * info, size_t size, void * ptr)
     }
 
   return match;
+#endif
 }