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, 285 insertions, 0 deletions

diff --git a/ldso/ldso/xtensa/elfinterp.c b/ldso/ldso/xtensa/elfinterp.c
new file mode 100644
index 000000000..a459431b1
--- /dev/null
+++ b/ldso/ldso/xtensa/elfinterp.c
@@ -0,0 +1,285 @@
+/* vi: set sw=4 ts=4: */
+/* Xtensa ELF shared library loader suppport
+ *
+ * Copyright (C) 2007 Tensilica Inc.
+ * Copyright (c) 1994-2000 Eric Youngdale, Peter MacDonald,
+ *                              David Engel, Hongjiu Lu and Mitch D'Souza
+ * Copyright (C) 2001-2004 Erik Andersen
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. The name of the above contributors may not be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include "ldso.h"
+
+unsigned long
+_dl_linux_resolver (struct elf_resolve *tpnt, int reloc_entry)
+{
+	int reloc_type;
+	ELF_RELOC *this_reloc;
+	char *strtab;
+	Elf32_Sym *symtab;
+	int symtab_index;
+	char *rel_addr;
+	char *new_addr;
+	char **got_addr;
+	char *symname;
+
+	rel_addr = (char *) tpnt->dynamic_info[DT_JMPREL];
+	this_reloc = (ELF_RELOC *) (rel_addr + reloc_entry);
+	reloc_type = ELF32_R_TYPE (this_reloc->r_info);
+	symtab_index = ELF32_R_SYM (this_reloc->r_info);
+
+	symtab = (Elf32_Sym *) tpnt->dynamic_info[DT_SYMTAB];
+	strtab = (char *) tpnt->dynamic_info[DT_STRTAB];
+	symname = strtab + symtab[symtab_index].st_name;
+
+	if (unlikely (reloc_type != R_XTENSA_JMP_SLOT)) {
+		_dl_dprintf (2, "%s: Incorrect relocation type in jump relocations\n",
+					 _dl_progname);
+		_dl_exit (1);
+	}
+
+	/* Address of the literal to fix up.  */
+	got_addr = (char **) (this_reloc->r_offset + tpnt->loadaddr);
+
+	/* Get the address of the GOT entry.  */
+	new_addr = _dl_find_hash (symname, tpnt->symbol_scope, tpnt,
+							  ELF_RTYPE_CLASS_PLT);
+	if (unlikely (!new_addr)) {
+		_dl_dprintf (2, "%s: can't resolve symbol '%s'\n",
+					 _dl_progname, symname);
+		_dl_exit (1);
+	}
+
+#if defined (__SUPPORT_LD_DEBUG__)
+	if (_dl_debug_bindings) {
+		_dl_dprintf (_dl_debug_file, "\nresolve function: %s", symname);
+		if (_dl_debug_detail)
+			_dl_dprintf (_dl_debug_file, "\n\tpatched %x ==> %x @ %x\n",
+						 *got_addr, new_addr, got_addr);
+	}
+	if (!_dl_debug_nofixups)
+		*got_addr = new_addr;
+#else
+	*got_addr = new_addr;
+#endif
+
+	return (unsigned long) new_addr;
+}
+
+
+static int
+_dl_parse (struct elf_resolve *tpnt, struct dyn_elf *scope,
+		   unsigned long rel_addr, unsigned long rel_size,
+		   int (*reloc_fnc) (struct elf_resolve *tpnt, struct dyn_elf *scope,
+							 ELF_RELOC *rpnt, Elf32_Sym *symtab, char *strtab))
+{
+	unsigned int i;
+	char *strtab;
+	Elf32_Sym *symtab;
+	ELF_RELOC *rpnt;
+	int symtab_index;
+
+	/* Parse the relocation information.  */
+	rpnt = (ELF_RELOC *) rel_addr;
+	rel_size /= sizeof (ELF_RELOC);
+
+	symtab = (Elf32_Sym *) tpnt->dynamic_info[DT_SYMTAB];
+	strtab = (char *) tpnt->dynamic_info[DT_STRTAB];
+
+	for (i = 0; i < rel_size; i++, rpnt++) {
+		int res;
+
+		symtab_index = ELF32_R_SYM (rpnt->r_info);
+
+		debug_sym (symtab, strtab, symtab_index);
+		debug_reloc (symtab, strtab, rpnt);
+
+		res = reloc_fnc (tpnt, scope, rpnt, symtab, strtab);
+
+		if (res == 0)
+			continue;
+
+		_dl_dprintf (2, "\n%s: ", _dl_progname);
+
+		if (symtab_index)
+			_dl_dprintf (2, "symbol '%s': ",
+						 strtab + symtab[symtab_index].st_name);
+
+		if (unlikely (res < 0)) {
+			int reloc_type = ELF32_R_TYPE (rpnt->r_info);
+#if defined (__SUPPORT_LD_DEBUG__)
+			_dl_dprintf (2, "can't handle reloc type %s\n",
+						 _dl_reltypes (reloc_type));
+#else
+			_dl_dprintf (2, "can't handle reloc type %x\n", reloc_type);
+#endif
+			_dl_exit (-res);
+		}
+		if (unlikely (res > 0)) {
+			_dl_dprintf (2, "can't resolve symbol\n");
+			return res;
+		}
+	}
+
+	return 0;
+}
+
+
+static int
+_dl_do_reloc (struct elf_resolve *tpnt, struct dyn_elf *scope,
+			  ELF_RELOC *rpnt, Elf32_Sym *symtab, char *strtab)
+{
+	int reloc_type;
+	int symtab_index;
+	char *symname;
+	Elf32_Sym *sym;
+	Elf32_Addr *reloc_addr;
+	Elf32_Addr symbol_addr;
+#if defined (__SUPPORT_LD_DEBUG__)
+	Elf32_Addr old_val;
+#endif
+
+	reloc_addr = (Elf32_Addr *) (tpnt->loadaddr + rpnt->r_offset);
+	reloc_type = ELF32_R_TYPE (rpnt->r_info);
+	symtab_index = ELF32_R_SYM (rpnt->r_info);
+	sym = &symtab[symtab_index];
+	symbol_addr = 0;
+	symname = strtab + sym->st_name;
+
+	if (symtab_index) {
+		symbol_addr = (Elf32_Addr)
+			_dl_find_hash (symname, scope, tpnt,
+						   elf_machine_type_class (reloc_type));
+
+		/*
+		 * We want to allow undefined references to weak symbols - this might
+		 * have been intentional.  We should not be linking local symbols
+		 * here, so all bases should be covered.
+		 */
+		if (unlikely (!symbol_addr &&
+					  ELF32_ST_BIND (sym->st_info) != STB_WEAK)) {
+			_dl_dprintf (2, "%s: can't resolve symbol '%s'\n",
+						 _dl_progname, symname);
+			_dl_exit (1);
+		}
+	}
+
+#if defined (__SUPPORT_LD_DEBUG__)
+	old_val = *reloc_addr;
+#endif
+
+	switch (reloc_type) {
+	case R_XTENSA_NONE:
+		break;
+
+	case R_XTENSA_GLOB_DAT:
+	case R_XTENSA_JMP_SLOT:
+		*reloc_addr = symbol_addr + rpnt->r_addend;
+		break;
+
+	case R_XTENSA_RTLD:
+		if (rpnt->r_addend == 1) {
+			/* Grab the function pointer stashed at the beginning of the
+			   GOT by the GOT_INIT function.  */
+			*reloc_addr = *(Elf32_Addr *) tpnt->dynamic_info[DT_PLTGOT];
+		} else if (rpnt->r_addend == 2) {
+			/* Store the link map for the object.  */
+			*reloc_addr = (Elf32_Addr) tpnt;
+		} else {
+			_dl_exit (1);
+		}
+		break;
+
+	case R_XTENSA_RELATIVE:
+		*reloc_addr += tpnt->loadaddr + rpnt->r_addend;
+		break;
+
+	default:
+		return -1; /* Calls _dl_exit(1).  */
+	}
+#if defined (__SUPPORT_LD_DEBUG__)
+	if (_dl_debug_reloc && _dl_debug_detail)
+		_dl_dprintf (_dl_debug_file, "\tpatched: %x ==> %x @ %x",
+					 old_val, *reloc_addr, reloc_addr);
+#endif
+
+	return 0;
+}
+
+
+static int
+_dl_do_lazy_reloc (struct elf_resolve *tpnt, struct dyn_elf *scope,
+				   ELF_RELOC *rpnt, Elf32_Sym *symtab, char *strtab)
+{
+	int reloc_type;
+	Elf32_Addr *reloc_addr;
+#if defined (__SUPPORT_LD_DEBUG__)
+	Elf32_Addr old_val;
+#endif
+
+	reloc_addr = (Elf32_Addr *) (tpnt->loadaddr + rpnt->r_offset);
+	reloc_type = ELF32_R_TYPE (rpnt->r_info);
+
+#if defined (__SUPPORT_LD_DEBUG__)
+	old_val = *reloc_addr;
+#endif
+
+	switch (reloc_type) {
+	case R_XTENSA_JMP_SLOT:
+		/* Perform a RELATIVE reloc on the GOT entry that transfers
+		   to the stub function.  */
+		*reloc_addr += tpnt->loadaddr;
+		break;
+	case R_XTENSA_NONE:
+		break;
+	default:
+		_dl_exit (1);
+	}
+
+#if defined (__SUPPORT_LD_DEBUG__)
+	if (_dl_debug_reloc && _dl_debug_detail)
+		_dl_dprintf (_dl_debug_file, "\tpatched: %x ==> %x @ %x",
+					 old_val, *reloc_addr, reloc_addr);
+#endif
+	return 0;
+
+}
+
+void
+_dl_parse_lazy_relocation_information (struct dyn_elf *rpnt,
+									   unsigned long rel_addr,
+									   unsigned long rel_size)
+{
+	(void) _dl_parse (rpnt->dyn, NULL, rel_addr, rel_size, _dl_do_lazy_reloc);
+}
+
+int
+_dl_parse_relocation_information (struct dyn_elf *rpnt,
+								  unsigned long rel_addr,
+								  unsigned long rel_size)
+{
+	return _dl_parse (rpnt->dyn, rpnt->dyn->symbol_scope, rel_addr, rel_size,
+					  _dl_do_reloc);
+}