Chris Zankel writes:

The following patches add support for the Xtensa processor architecture
to uClibc. They are based on a recent SVN checkout (12/05/2007).

The first patch (attached to this post) adds Xtensa support to various
shared configuration and make files. The following patches then include
the Xtensa specific files and directories.

I welcome any feedback and would appreciate it if you could include the
patches into the mainline tree. I am certainly committed to maintain the port. 

Bob Wilson was kind enough to review the patches.

Some notes about the architecture: Xtensa is a configurable and
extensible processor architecture developed by Tensilica. For more
information, please visit: www.linux-xtensa.org.

1 files changed, 132 insertions, 0 deletions

diff --git a/ldso/ldso/xtensa/dl-sysdep.h b/ldso/ldso/xtensa/dl-sysdep.h
new file mode 100644
index 000000000..afbbf3bfe
--- /dev/null
+++ b/ldso/ldso/xtensa/dl-sysdep.h
@@ -0,0 +1,132 @@
+/* Machine-dependent ELF dynamic relocation.
+   Parts copied from glibc/sysdeps/xtensa/dl-machine.h
+   Copyright (C) 2001, 2007 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.
+
+   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, write to the Free
+   Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
+   Boston, MA 02110-1301, USA.  */
+
+/* Define this if the system uses RELOCA.  */
+#define ELF_USES_RELOCA
+#include <elf.h>
+#include <link.h>
+
+/* Translate a processor specific dynamic tag to the index
+   in l_info array.  */
+#define DT_XTENSA(x) (DT_XTENSA_##x - DT_LOPROC + DT_NUM + OS_NUM)
+
+typedef struct xtensa_got_location_struct {
+  Elf32_Off offset;
+  Elf32_Word length;
+} xtensa_got_location;
+
+/* Initialization sequence for the GOT.  */
+#define INIT_GOT(GOT_BASE, MODULE) \
+  do {									      \
+    xtensa_got_location *got_loc;					      \
+    Elf32_Addr l_addr = MODULE->loadaddr;				      \
+    int x;								      \
+									      \
+    got_loc = (xtensa_got_location *)					      \
+      (MODULE->dynamic_info[DT_XTENSA (GOT_LOC_OFF)] + l_addr);		      \
+									      \
+    for (x = 0; x < MODULE->dynamic_info[DT_XTENSA (GOT_LOC_SZ)]; x++)	      \
+      {									      \
+	Elf32_Addr got_start, got_end;					      \
+	got_start = got_loc[x].offset & ~(PAGE_SIZE - 1);		      \
+	got_end = ((got_loc[x].offset + got_loc[x].length + PAGE_SIZE - 1)    \
+		   & ~(PAGE_SIZE - 1));					      \
+	_dl_mprotect ((void *)(got_start + l_addr) , got_end - got_start,     \
+		      PROT_READ | PROT_WRITE | PROT_EXEC);		      \
+      }									      \
+									      \
+    /* Fill in first GOT entry according to the ABI.  */		      \
+    GOT_BASE[0] = (unsigned long) _dl_linux_resolve;			      \
+  } while (0)
+
+/* Parse dynamic info */
+#define ARCH_NUM 2
+#define ARCH_DYNAMIC_INFO(dpnt, dynamic, debug_addr) \
+  do {									\
+    if (dpnt->d_tag == DT_XTENSA_GOT_LOC_OFF)				\
+      dynamic[DT_XTENSA (GOT_LOC_OFF)] = dpnt->d_un.d_ptr;		\
+    else if (dpnt->d_tag == DT_XTENSA_GOT_LOC_SZ)			\
+      dynamic[DT_XTENSA (GOT_LOC_SZ)] = dpnt->d_un.d_val;		\
+  } while (0)
+
+/* Here we define the magic numbers that this dynamic loader should accept. */
+#define MAGIC1 EM_XTENSA
+#undef	MAGIC2
+
+/* Used for error messages. */
+#define ELF_TARGET "Xtensa"
+
+struct elf_resolve;
+extern unsigned long _dl_linux_resolver (struct elf_resolve *, int);
+
+/* 4096 bytes alignment */
+#define PAGE_ALIGN 0xfffff000
+#define ADDR_ALIGN 0xfff
+#define OFFS_ALIGN 0x7ffff000
+
+/* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry, so
+   undefined references should not be allowed to define the value.  */
+#define elf_machine_type_class(type) \
+  (((type) == R_XTENSA_JMP_SLOT) * ELF_RTYPE_CLASS_PLT)
+
+/* Return the link-time address of _DYNAMIC.  */
+static inline Elf32_Addr
+elf_machine_dynamic (void)
+{
+  /* This function is only used while bootstrapping the runtime linker.
+     The "_DYNAMIC" symbol is always local so its GOT entry will initially
+     contain the link-time address.  */
+  return (Elf32_Addr) &_DYNAMIC;
+}
+
+/* Return the run-time load address of the shared object.  */
+static inline Elf32_Addr
+elf_machine_load_address (void)
+{
+  Elf32_Addr addr, tmp;
+
+  /* At this point, the runtime linker is being bootstrapped and the GOT
+     entry used for ".Lhere" will contain the link address.  The CALL0 will
+     produce the dynamic address of ".Lhere" + 3.  Thus, the end result is
+     equal to "dynamic_address(.Lhere) - link_address(.Lhere)".  */
+  __asm__ ("\
+	movi	%0, .Lhere\n\
+	mov	%1, a0\n\
+.Lhere:	_call0	0f\n\
+	.align	4\n\
+0:	sub	%0, a0, %0\n\
+	mov	a0, %1"
+	   : "=a" (addr), "=a" (tmp));
+
+  return addr - 3;
+}
+
+static inline void
+elf_machine_relative (Elf32_Addr load_off, const Elf32_Addr rel_addr,
+		      Elf32_Word relative_count)
+{
+  Elf32_Rela *rpnt = (Elf32_Rela *) rel_addr;
+  while (relative_count--)
+    {
+      Elf32_Addr *const reloc_addr = (Elf32_Addr *) (load_off + rpnt->r_offset);
+      *reloc_addr += load_off + rpnt->r_addend;
+      rpnt++;
+    }
+}