Patchwork [2/6] ldso: Add ARC support

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Submitter Vineet Gupta
Date Nov. 18, 2013, 1:06 p.m.
Message ID <1384779973-30342-3-git-send-email-vgupta@synopsys.com>
Download mbox | patch
Permalink /patch/292074/
State Superseded
Headers show

Comments

Vineet Gupta - Nov. 18, 2013, 1:06 p.m.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 ldso/ldso/arc/dl-debug.h    |  68 +++++++++++
 ldso/ldso/arc/dl-startup.h  |  89 ++++++++++++++
 ldso/ldso/arc/dl-syscalls.h |   5 +
 ldso/ldso/arc/dl-sysdep.h   | 150 ++++++++++++++++++++++++
 ldso/ldso/arc/elfinterp.c   | 279 ++++++++++++++++++++++++++++++++++++++++++++
 ldso/ldso/arc/resolve.S     |  57 +++++++++
 6 files changed, 648 insertions(+)
 create mode 100644 ldso/ldso/arc/dl-debug.h
 create mode 100644 ldso/ldso/arc/dl-startup.h
 create mode 100644 ldso/ldso/arc/dl-syscalls.h
 create mode 100644 ldso/ldso/arc/dl-sysdep.h
 create mode 100644 ldso/ldso/arc/elfinterp.c
 create mode 100644 ldso/ldso/arc/resolve.S

Patch

diff --git a/ldso/ldso/arc/dl-debug.h b/ldso/ldso/arc/dl-debug.h
new file mode 100644
index 000000000000..93ce1e6c729d
--- /dev/null
+++ b/ldso/ldso/arc/dl-debug.h
@@ -0,0 +1,68 @@ 
+/*
+ * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
+ *
+ * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
+ */
+static const char *_dl_reltypes_tab[] =
+{
+	"R_ARC_NONE",		/* 0 */
+	"R_ARC_8",
+	"R_ARC_16",
+	"R_ARC_24",
+	"R_ARC_32",
+	"R_ARC_B26",		/* 5 */
+	"R_ARC_B22_PCREL",
+	"R_ARC_H30",
+	"R_ARC_N8",
+	"R_ARC_N16",
+	"R_ARC_N24",		/* 10 */
+	"R_ARC_N32",
+	"R_ARC_SDA",
+	"R_ARC_SECTOFF",
+	"R_ARC_S21H_PCREL",
+	"R_ARC_S21W_PCREL",	/* 15 */
+	"R_ARC_S25H_PCREL",
+	"R_ARC_S25W_PCREL",
+	"R_ARC_SDA32",
+	"R_ARC_SDA_LDST",
+	"R_ARC_SDA_LDST1",	/* 20 */
+	"R_ARC_SDA_LDST2",
+	"R_ARC_SDA16_LD",
+	"R_ARC_SDA16_LD1",
+	"R_ARC_SDA16_LD2",
+	"R_ARC_S13_PCREL",	/* 25 */
+	"R_ARC_W",
+	"R_ARC_32_ME",
+	"R_ARC_N32_ME",
+	"R_ARC_SECTOFF_ME",
+	"R_ARC_SDA32_ME",	/* 30 */
+	"R_ARC_W_ME",
+	"R_ARC_H30_ME",
+	"R_ARC_SECTOFF_U8",
+	"R_ARC_SECTOFF_S9",
+	"R_AC_SECTOFF_U8",	/* 35 */
+	"R_AC_SECTOFF_U8_1",
+	"R_AC_SECTOFF_U8_2",
+	"R_AC_SECTOFF_S9",
+	"R_AC_SECTOFF_S9_1",
+	"R_AC_SECTOFF_S9_2",	/* 40 */
+	"R_ARC_SECTOFF_ME_1",
+	"R_ARC_SECTOFF_ME_2",
+	"R_ARC_SECTOFF_1",
+	"R_ARC_SECTOFF_2",
+	"",			/* 45 */
+	"",
+	"",
+	"",
+	"",
+	"R_ARC_PC32",		/* 50 */
+	"R_ARC_GOTPC32",
+	"R_ARC_PLT32",
+	"R_ARC_COPY",
+	"R_ARC_GLOB_DAT",
+	"R_ARC_JMP_SLOT",	/* 55 */
+	"R_ARC_RELATIVE",
+	"R_ARC_GOTOFF",
+	"R_ARC_GOTPC",
+	"R_ARC_GOT32",
+};
diff --git a/ldso/ldso/arc/dl-startup.h b/ldso/ldso/arc/dl-startup.h
new file mode 100644
index 000000000000..ae20696e4fd5
--- /dev/null
+++ b/ldso/ldso/arc/dl-startup.h
@@ -0,0 +1,89 @@ 
+/*
+ * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
+ *
+ * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
+ */
+
+/*
+ * vineetg: Refactoring/cleanup of loader entry point
+ *  Removed 6 useless insns
+ * Joern Improved it even further:
+ *  -better insn scheduling
+ *  -no need for conditional code for _dl_skip_args
+ *  -use of assembler .&2 expressions vs. @gotpc refs (avoids need for GP)
+ *
+ * What this code does:
+ *  -ldso starts execution here when kernel returns from execve()
+ *  -calls into generic ldso entry point _dl_start( )
+ *  -optionally adjusts argc for executable if exec passed as cmd
+ *  -calls into app main with address of finaliser
+ */
+__asm__(
+    ".section .text                                             \n"
+    ".align 4                                                  	\n"
+    ".global _start                                             \n"
+    ".hidden _start                                             \n"
+    ".type  _start,@function                                    \n"
+
+    "_start:                                                    \n"
+    "   ; ldso entry point, returns app entry point             \n"
+    "   bl.d    _dl_start                                       \n"
+    "   mov_s   r0, sp          ; pass ptr to aux vector tbl    \n"
+
+    "   ; If ldso ran as cmd with executable file nm as arg     \n"
+    "   ; as arg, skip the extra args calc by dl_start()        \n"
+    "   ld_s    r1, [sp]       ; orig argc from aux-vec Tbl     \n"
+#ifdef STAR_9000535888_FIXED
+    "   ld      r12, [pcl, _dl_skip_args-.+(.&2)]               \n"
+#else
+    "   add     r12, pcl, _dl_skip_args-.+(.&2)                 \n"
+    "   ld      r12, [r12]                                      \n"
+#endif
+
+    "   add     r2, pcl, _dl_fini-.+(.&2)   ; finalizer         \n"
+
+    "   add2    sp, sp, r12    ; discard argv entries from stack\n"
+    "   sub_s   r1, r1, r12    ; adjusted argc, on stack        \n"
+    "   st_s    r1, [sp]                                        \n"
+
+    "   j_s.d   [r0]           ; app entry point                \n"
+    "   mov_s   r0, r2         ; ptr to finalizer _dl_fini      \n"
+
+    ".size  _start,.-_start                                     \n"
+    ".previous                                                  \n"
+);
+
+/*
+ * Get a pointer to the argv array.  On many platforms this can be just
+ * the address if the first argument, on other platforms we need to
+ * do something a little more subtle here.
+ */
+#define GET_ARGV(ARGVP, ARGS) ARGVP = ((unsigned long*) ARGS + 1)
+
+/*
+ * Dynamic loader bootstrapping:
+ * Since we don't modify text at runtime, these can only be data relos
+ * (so safe to assume that they are word aligned).
+ * And also they HAVE to be RELATIVE relos only
+ * @RELP is the relo entry being processed
+ * @REL is the pointer to the address we are relocating.
+ * @SYMBOL is the symbol involved in the relocation
+ * @LOAD is the load address.
+ */
+
+#define PERFORM_BOOTSTRAP_RELOC(RELP,REL,SYMBOL,LOAD,SYMTAB)		\
+do {									\
+	int type = ELF32_R_TYPE((RELP)->r_info);			\
+	if (likely(type == R_ARC_RELATIVE))				\
+		*REL += (unsigned long) LOAD;				\
+	else								\
+		_dl_exit(1);						\
+}while(0)
+
+/*
+ * This will go away once we have DT_RELACOUNT
+ */
+#define ARCH_NEEDS_BOOTSTRAP_RELOCS
+
+/* we dont need to spit out argc, argv etc for debugging */
+#define NO_EARLY_SEND_STDERR    1
diff --git a/ldso/ldso/arc/dl-syscalls.h b/ldso/ldso/arc/dl-syscalls.h
new file mode 100644
index 000000000000..d0bf9c1f6e9c
--- /dev/null
+++ b/ldso/ldso/arc/dl-syscalls.h
@@ -0,0 +1,5 @@ 
+/*
+ * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
+ *
+ * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
+ */
diff --git a/ldso/ldso/arc/dl-sysdep.h b/ldso/ldso/arc/dl-sysdep.h
new file mode 100644
index 000000000000..fee47084a2a9
--- /dev/null
+++ b/ldso/ldso/arc/dl-sysdep.h
@@ -0,0 +1,150 @@ 
+/*
+ * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
+ *
+ * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
+ */
+
+#include "elf.h"
+
+/*
+ * Define this if the system uses RELOCA.
+ */
+#define ELF_USES_RELOCA
+
+/*
+ * Dynamic Linking ABI for ARCompact ISA
+ *
+ *		      PLT
+ *	--------------------------------
+ *	|  ld r11, [pcl, off-to-GOT[1]  |  0   (20 bytes)
+ *	|				|  4
+ * plt0	|  ld r10, [pcl, off-to-GOT[2]	|  8
+ *	|				| 12
+ *	|  j [r10]			| 16
+ *	--------------------------------
+ *	|    Base address of GOT	| 20
+ *	--------------------------------
+ *	|  ld r12, [pcl, off-to-GOT[3]  | 24   (12 bytes each)
+ * plt1 |				|
+ *	|  j_s.d  [r12]			| 32
+ *	|  mov_s  r12, pcl		| 34
+ *	--------------------------------
+ *	|				| 36
+ *	~				~
+ *	~				~
+ *	|				|
+ *	--------------------------------
+ *
+ *	     GOT
+ *	--------------
+ *	|    [0]      |
+ *	--------------
+ *	|    [1]      |  Module info - setup by ldso
+ *	--------------
+ *	|    [2]      |  resolver entry point
+ *	--------------
+ *	|    [3]      |
+ *	|    ...      |  Runtime address for function symbols
+ *	|    [f]      |
+ *	--------------
+ *	|    [f+1]    |
+ *	|    ...      |  Runtime address for data symbols
+ *	|    [last]   |
+ *	--------------
+ */
+
+/*
+ * Initialization sequence for a GOT.
+ * Caller elf_resolve() seeds @GOT_BASE from DT_PLTGOT - which essentially is
+ * pointer to first PLT entry. The actual GOT base is 5th word in PLT
+ *
+ */
+#define INIT_GOT(GOT_BASE,MODULE)					\
+do {									\
+	unsigned long *__plt_base = (unsigned long *)GOT_BASE;		\
+	GOT_BASE = (unsigned long *)(__plt_base[5] +			\
+		                     (unsigned long)MODULE->loadaddr);	\
+	GOT_BASE[1] = (unsigned long) MODULE;				\
+	GOT_BASE[2] = (unsigned long) _dl_linux_resolve;		\
+} while(0)
+
+/* Here we define the magic numbers that this dynamic loader should accept */
+#define MAGIC1 EM_ARCOMPACT
+#undef  MAGIC2
+
+/* Used for error messages */
+#define ELF_TARGET "ARC"
+
+struct elf_resolve;
+extern unsigned long _dl_linux_resolver(struct elf_resolve * tpnt,
+					 unsigned int plt_pc);
+
+extern unsigned __udivmodsi4(unsigned, unsigned) attribute_hidden;
+
+#define do_rem(result, n, base)  ((result) =				\
+									\
+	__builtin_constant_p (base) ? (n) % (unsigned) (base) :		\
+	__extension__ ({						\
+		register unsigned r1 __asm__ ("r1") = (base);		\
+									\
+		__asm("bl.d @__udivmodsi4` mov r0,%1"			\
+		: "=r" (r1)						\
+	        : "r" (n), "r" (r1)					\
+	        : "r0", "r2", "r3", "r4", "lp_count", "blink", "cc");	\
+									\
+		r1;							\
+	})								\
+)
+
+/* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry, so
+   PLT entries 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.  */
+#define elf_machine_type_class(type) \
+  ((((type) == R_ARC_JMP_SLOT) * ELF_RTYPE_CLASS_PLT)	\
+   | (((type) == R_ARC_COPY) * ELF_RTYPE_CLASS_COPY))
+
+/*
+ * Get the runtime address of GOT[0]
+ */
+static __always_inline Elf32_Addr elf_machine_dynamic(void)
+{
+	Elf32_Addr dyn;
+
+	__asm__("ld %0,[pcl,_DYNAMIC@gotpc]\n\t" : "=r" (dyn));
+	return dyn;
+
+/*
+ * Another way would have been to simply return GP, which due to some
+ * PIC reference would be automatically setup by gcc in caller
+ *	register Elf32_Addr *got __asm__ ("gp"); return *got;
+ */
+}
+
+/* Return the run-time load address of the shared object.  */
+static __always_inline Elf32_Addr elf_machine_load_address(void)
+{
+    /* To find the loadaddr we subtract the runtime addr of any symbol
+     * say _dl_start from it's build-time addr.
+     */
+	Elf32_Addr addr, tmp;
+	__asm__ (
+        "ld  %1, [pcl, _dl_start@gotpc] ;build addr of _dl_start   \n"
+        "add %0, pcl, _dl_start-.+(.&2) ;runtime addr of _dl_start \n"
+        "sub %0, %0, %1                 ;delta                     \n"
+        : "=&r" (addr), "=r"(tmp)
+    );
+	return addr;
+}
+
+static __always_inline void
+elf_machine_relative (Elf32_Addr load_off, const Elf32_Addr rel_addr,
+		      Elf32_Word relative_count)
+{
+	 Elf32_Rel * rpnt = (void *) rel_addr;
+	--rpnt;
+	do {
+		Elf32_Addr *const reloc_addr = (void *) (load_off + (++rpnt)->r_offset);
+		*reloc_addr += load_off;
+	} while (--relative_count);
+}
diff --git a/ldso/ldso/arc/elfinterp.c b/ldso/ldso/arc/elfinterp.c
new file mode 100644
index 000000000000..4cf2d1c3d848
--- /dev/null
+++ b/ldso/ldso/arc/elfinterp.c
@@ -0,0 +1,279 @@ 
+/*
+ * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
+ *
+ * Lots of code copied from ../i386/elfinterp.c, so:
+ * Copyright (c) 1994-2000 Eric Youngdale, Peter MacDonald,
+ *               David Engel, Hongjiu Lu and Mitch D'Souza
+ * Copyright (C) 2001-2002, Erik Andersen
+ * All rights reserved.
+ *
+ * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
+ */
+#include "ldso.h"
+
+#define ARC_PLT_SIZE	12
+
+unsigned long
+_dl_linux_resolver(struct elf_resolve *tpnt, unsigned int plt_pc)
+{
+	ELF_RELOC *this_reloc, *rel_base;
+	char *strtab, *symname, *new_addr;
+	ElfW(Sym) *symtab;
+	int symtab_index;
+	unsigned int *got_addr;
+	unsigned long plt_base;
+	int plt_idx;
+
+	/* start of .rela.plt */
+	rel_base = (ELF_RELOC *)(tpnt->dynamic_info[DT_JMPREL]);
+
+	/* starts of .plt (addr of PLT0) */
+	plt_base = tpnt->dynamic_info[DT_PLTGOT];
+
+	/*
+	 * compute the idx of the yet-unresolved PLT entry in .plt
+	 * Same idx will be used to find the relo entry in .rela.plt
+	 */
+	plt_idx = (plt_pc - plt_base)/ARC_PLT_SIZE  - 2; /* ignoring 2 dummy PLTs */
+
+	this_reloc = rel_base + plt_idx;
+
+	symtab_index = ELF_R_SYM(this_reloc->r_info);
+	symtab = (ElfW(Sym) *)(intptr_t) (tpnt->dynamic_info[DT_SYMTAB]);
+	strtab = (char *) (tpnt->dynamic_info[DT_STRTAB]);
+	symname= strtab + symtab[symtab_index].st_name;
+
+	/* relo-offset to fixup, shd be a .got entry */
+	got_addr = (unsigned int *)(this_reloc->r_offset + tpnt->loadaddr);
+
+	/* Get the address of the GOT entry */
+	new_addr = _dl_find_hash(symname, &_dl_loaded_modules->symbol_scope, tpnt,
+				 ELF_RTYPE_CLASS_PLT, NULL);
+
+	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 ==> %pc @ %pl\n",
+					*got_addr, new_addr, got_addr);
+	}
+
+	if (!_dl_debug_nofixups)
+		*got_addr = (unsigned int)new_addr;
+#else
+	/* Update the .got entry with the runtime address of symbol */
+	*got_addr = (unsigned int)new_addr;
+#endif
+
+	/*
+	 * Return the new addres, where the asm trampoline will jump to
+	 *  after re-setting up the orig args
+	 */
+	return (unsigned long) new_addr;
+}
+
+
+static int
+_dl_do_reloc(struct elf_resolve *tpnt, struct r_scope_elem *scope,
+	     ELF_RELOC *rpnt, ElfW(Sym) *symtab, char *strtab)
+{
+	int reloc_type;
+	int symtab_index;
+	char *symname;
+	unsigned long *reloc_addr;
+	unsigned long symbol_addr;
+#if defined __SUPPORT_LD_DEBUG__
+	unsigned long old_val = 0;
+#endif
+	struct symbol_ref sym_ref;
+
+	reloc_addr   = (unsigned long *)(tpnt->loadaddr + rpnt->r_offset);
+	reloc_type   = ELF_R_TYPE(rpnt->r_info);
+	symtab_index = ELF_R_SYM(rpnt->r_info);
+	symbol_addr  = 0;
+
+	sym_ref.sym = &symtab[symtab_index];
+	sym_ref.tpnt = NULL;
+
+#if defined __SUPPORT_LD_DEBUG__
+	if (reloc_addr)
+		old_val = *reloc_addr;
+#endif
+
+	if (symtab_index) {
+		symname = strtab + symtab[symtab_index].st_name;
+		symbol_addr = (unsigned long) _dl_find_hash(symname, scope, tpnt,
+				elf_machine_type_class(reloc_type), &sym_ref);
+
+		/*
+		 * 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
+		    && ELF_ST_BIND(symtab[symtab_index].st_info) != STB_WEAK)) {
+			/* Non-fatal if called from dlopen, hence different ret code */
+			return 1;
+		}
+	} else if (reloc_type == R_ARC_RELATIVE ) {
+		*reloc_addr += tpnt->loadaddr;
+		goto log_entry;
+	}
+
+	switch (reloc_type) {
+	case R_ARC_32:
+		*reloc_addr += symbol_addr + rpnt->r_addend;
+		break;
+	case R_ARC_PC32:
+		*reloc_addr += symbol_addr + rpnt->r_addend - (unsigned long) reloc_addr;
+		break;
+	case R_ARC_GLOB_DAT:
+	case R_ARC_JMP_SLOT:
+		*reloc_addr = symbol_addr;
+		break;
+	case R_ARC_COPY:
+		_dl_memcpy((void *) reloc_addr,(void *) symbol_addr,
+				symtab[symtab_index].st_size);
+		break;
+	default:
+		return -1;
+	}
+
+log_entry:
+#if defined __SUPPORT_LD_DEBUG__
+	if(_dl_debug_detail)
+		_dl_dprintf(_dl_debug_file,"\tpatched: %lx ==> %lx @ %pl: addend %x ",
+				old_val, *reloc_addr, reloc_addr, rpnt->r_addend);
+#endif
+
+	return 0;
+}
+
+static int
+_dl_do_lazy_reloc(struct elf_resolve *tpnt, struct r_scope_elem *scope,
+		  ELF_RELOC *rpnt)
+{
+	int reloc_type;
+	unsigned long *reloc_addr;
+#if defined __SUPPORT_LD_DEBUG__
+	unsigned long old_val;
+#endif
+
+	reloc_addr = (unsigned long *)(tpnt->loadaddr + rpnt->r_offset);
+	reloc_type = ELF_R_TYPE(rpnt->r_info);
+
+#if defined __SUPPORT_LD_DEBUG__
+	old_val = *reloc_addr;
+#endif
+
+	switch (reloc_type) {
+	case R_ARC_JMP_SLOT:
+		*reloc_addr += tpnt->loadaddr;
+		break;
+	default:
+		return -1;
+	}
+
+#if defined __SUPPORT_LD_DEBUG__
+	if(_dl_debug_reloc && _dl_debug_detail)
+		_dl_dprintf(_dl_debug_file, "\tpatched: %lx ==> %lx @ %pl\n",
+				old_val, *reloc_addr, reloc_addr);
+#endif
+
+	return 0;
+}
+
+#define ___DO_LAZY  1
+#define ___DO_NOW   2
+
+static int _dl_parse(struct elf_resolve *tpnt, struct r_scope_elem *scope,
+		     unsigned long rel_addr, unsigned long rel_size, int type)
+{
+	unsigned int i;
+	char *strtab;
+	ElfW(Sym) *symtab;
+	ELF_RELOC *rpnt;
+	int symtab_index;
+	int res = 0;
+
+	/* Now parse the relocation information */
+	rpnt = (ELF_RELOC *)(intptr_t) (rel_addr);
+	rel_size = rel_size / sizeof(ELF_RELOC);
+
+	symtab = (ElfW(Sym) *)(intptr_t) (tpnt->dynamic_info[DT_SYMTAB]);
+	strtab = (char *) (tpnt->dynamic_info[DT_STRTAB]);
+
+	for (i = 0; i < rel_size; i++, rpnt++) {
+
+		symtab_index = ELF_R_SYM(rpnt->r_info);
+
+		debug_sym(symtab,strtab,symtab_index);
+		debug_reloc(symtab,strtab,rpnt);
+
+		/* constant propagation subsumes the 'if' */
+		if (type == ___DO_LAZY)
+			res = _dl_do_lazy_reloc(tpnt, scope, rpnt);
+		else
+			res = _dl_do_reloc(tpnt, scope, rpnt, symtab, strtab);
+
+		if (res != 0)
+			break;
+	}
+
+	if (unlikely(res != 0)) {
+		if (res < 0) {
+			int reloc_type = ELF_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);
+		} else {
+			_dl_dprintf(2, "can't resolve symbol\n");
+			/* Fall thru to return res */
+		}
+	}
+
+	return res;
+}
+
+void
+_dl_parse_lazy_relocation_information(struct dyn_elf *rpnt,
+				      unsigned long rel_addr,
+				      unsigned long rel_size)
+{
+	/* This func is called for processing .rela.plt of loaded module(s)
+	 * The relo entries handled are JMP_SLOT type for fixing up .got slots
+	 * for external function calls.
+	 * This function doesn't resolve the slots: that is done lazily at
+	 * runtime. The build linker (at least thats what happens for ARC) had
+	 * pre-init the .got slots to point to PLT0. All that is done here is
+	 * to fix them up to point to load value of PLT0 (as opposed to the
+	 * build value).
+	 * On ARC, the loadaddr of dyn exec is zero, thus elfaddr == loadaddr
+	 * Thus there is no point in adding "0" to values and un-necessarily
+	 * stir up the caches and TLB.
+	 * For lsdo processing busybox binary, this skips over 380 relo entries
+	 */
+	if (rpnt->dyn->loadaddr != 0)
+		_dl_parse(rpnt->dyn, NULL, rel_addr, rel_size, ___DO_LAZY);
+}
+
+int
+_dl_parse_relocation_information(struct dyn_elf  *rpnt,
+				 struct r_scope_elem *scope,
+				 unsigned long rel_addr,
+				 unsigned long rel_size)
+{
+	return _dl_parse(rpnt->dyn, scope, rel_addr, rel_size, ___DO_NOW);
+}
diff --git a/ldso/ldso/arc/resolve.S b/ldso/ldso/arc/resolve.S
new file mode 100644
index 000000000000..7e9bb8d4f10b
--- /dev/null
+++ b/ldso/ldso/arc/resolve.S
@@ -0,0 +1,57 @@ 
+/*
+ * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
+ *
+ * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
+ */
+
+#include <sysdep.h>
+#include <sys/syscall.h>
+
+; Save the registers which resolver could possibly clobber
+; 	r0-r9: args to the function - symbol being resolved
+; 	r10-r12 are already clobbered by PLTn, PLT0 thus neednot be saved
+
+.macro	SAVE_CALLER_SAVED
+	push_s	r0
+	push_s	r1
+	push_s	r2
+	push_s	r3
+	st.a	r4, [sp, -4]
+	st.a	r5, [sp, -4]
+	st.a	r6, [sp, -4]
+	st.a	r7, [sp, -4]
+	st.a	r8, [sp, -4]
+	st.a	r9, [sp, -4]
+	push_s	blink
+.endm
+
+.macro RESTORE_CALLER_SAVED_BUT_R0
+	ld.ab	blink,[sp, 4]
+	ld.ab	r9, [sp, 4]
+	ld.ab	r8, [sp, 4]
+	ld.ab	r7, [sp, 4]
+	ld.ab	r6, [sp, 4]
+	ld.ab	r5, [sp, 4]
+	ld.ab	r4, [sp, 4]
+	pop_s   r3
+	pop_s   r2
+	pop_s   r1
+.endm
+
+; Upon entry, PLTn, which led us here, sets up the following regs
+; 	r11 = Module info (tpnt pointer as expected by resolver)
+;	r12 = PC of the PLTn itself - needed by resolver to find
+;	      corresponding .rela.plt entry
+
+ENTRY(_dl_linux_resolve)
+	; args to func being resolved, which resolver might clobber
+	SAVE_CALLER_SAVED
+
+	mov_s 	r1, r12
+	bl.d  	_dl_linux_resolver
+	mov   	r0, r11
+
+	RESTORE_CALLER_SAVED_BUT_R0
+	j_s.d   [r0]    ; r0 has resolved function addr
+	pop_s   r0      ; restore first arg to resolved call
+END(_dl_linux_resolve)