Separate out the ELF relocation code from the ELF loader, and add

better relocation support for the amd64 and i386 platforms. This
should not result in any change in functionality, but moves a step
towards supporting the relocatable object file modules on amd64.

The same hack/trick as load_elf*.c uses is used here to simultaneously
support both elf32 and elf64 on amd64 and i386.

sys/boot/common/Makefile.inc

@@ -6,12 +6,13 @@ SRCS+=	module.c panic.c
 
 .if ${MACHINE_ARCH} == "i386" || ${MACHINE_ARCH} == "amd64"
 SRCS+=	load_elf32.c load_elf64.c
+SRCS+=	reloc_elf32.c reloc_elf64.c
 .endif
 .if ${MACHINE_ARCH} == "powerpc"
-SRCS+=	load_elf32.c
+SRCS+=	load_elf32.c reloc_elf32.c
 .endif
 .if ${MACHINE_ARCH} == "sparc64" || ${MACHINE_ARCH} == "ia64" || ${MACHINE_ARCH} == "alpha"
-SRCS+=	load_elf64.c
+SRCS+=	load_elf64.c reloc_elf64.c
 .endif
 
 .if defined(LOADER_NET_SUPPORT)

sys/boot/common/bootstrap.h

@@ -235,7 +235,17 @@ int  file_addmodule(struct preloaded_file *fp, char *modname, int version,
 
 /* MI module loaders */
 #ifdef __elfN
+/* Relocation types. */
+#define ELF_RELOC_REL	1
+#define ELF_RELOC_RELA	2
+
+struct elf_file;
+typedef Elf_Addr (symaddr_fn)(struct elf_file *ef, Elf_Word symidx);
+
 int	__elfN(loadfile)(char *filename, u_int64_t dest, struct preloaded_file **result);
+int	__elfN(reloc)(struct elf_file *ef, symaddr_fn *symaddr,
+	    const void *reldata, int reltype, Elf_Addr relbase,
+	    Elf_Addr dataaddr, void *data, size_t len);
 #endif
 
 /*

sys/boot/common/load_elf.c

@@ -58,6 +58,8 @@ typedef struct elf_file {
     Elf_Hashelt	nchains;
     Elf_Hashelt	*buckets;
     Elf_Hashelt	*chains;
+    Elf_Rel	*rel;
+    size_t	relsz;
     Elf_Rela	*rela;
     size_t	relasz;
     char	*strtab;
@@ -71,11 +73,10 @@ typedef struct elf_file {
 
 static int __elfN(loadimage)(struct preloaded_file *mp, elf_file_t ef, u_int64_t loadaddr);
 static int __elfN(lookup_symbol)(struct preloaded_file *mp, elf_file_t ef, const char* name, Elf_Sym* sym);
-#ifdef __sparc__
-static void __elfN(reloc_ptr)(struct preloaded_file *mp, elf_file_t ef,
-    void *p, void *val, size_t len);
-#endif
+static int __elfN(reloc_ptr)(struct preloaded_file *mp, elf_file_t ef,
+    Elf_Addr p, void *val, size_t len);
 static int __elfN(parse_modmetadata)(struct preloaded_file *mp, elf_file_t ef);
+static symaddr_fn __elfN(symaddr);
 static char	*fake_modname(const char *name);
 
 const char	*__elfN(kerneltype) = "elf kernel";
@@ -481,6 +482,12 @@ __elfN(loadimage)(struct preloaded_file *fp, elf_file_t ef, u_int64_t off)
 	case DT_SYMTAB:
 	    ef->symtab = (Elf_Sym*)(uintptr_t)(dp[i].d_un.d_ptr + off);
 	    break;
+	case DT_REL:
+	    ef->rel = (Elf_Rel *)(uintptr_t)(dp[i].d_un.d_ptr + off);
+	    break;
+	case DT_RELSZ:
+	    ef->relsz = dp[i].d_un.d_val;
+	    break;
 	case DT_RELA:
 	    ef->rela = (Elf_Rela *)(uintptr_t)(dp[i].d_un.d_ptr + off);
 	    break;
@@ -563,7 +570,7 @@ __elfN(parse_modmetadata)(struct preloaded_file *fp, elf_file_t ef)
     struct mod_version mver;
     Elf_Sym sym;
     char *s;
-    int modcnt, minfolen;
+    int error, modcnt, minfolen;
     Elf_Addr v, p, p_stop;
 
     if (__elfN(lookup_symbol)(fp, ef, "__start_set_modmetadata_set", &sym) != 0)
@@ -576,25 +583,31 @@ __elfN(parse_modmetadata)(struct preloaded_file *fp, elf_file_t ef)
     modcnt = 0;
     while (p < p_stop) {
 	COPYOUT(p, &v, sizeof(v));
-#ifdef __sparc64__
-	__elfN(reloc_ptr)(fp, ef, p, &v, sizeof(v));
-#else
-	v += ef->off;
-#endif
+	error = __elfN(reloc_ptr)(fp, ef, p, &v, sizeof(v));
+	if (error == EOPNOTSUPP)
+	    v += ef->off;
+	else if (error != 0)
+	    return (error);
 #if defined(__i386__) && __ELF_WORD_SIZE == 64
 	COPYOUT(v, &md64, sizeof(md64));
+	error = __elfN(reloc_ptr)(fp, ef, v, &md64, sizeof(md64));
+	if (error == EOPNOTSUPP) {
+	    md64.md_cval += ef->off;
+	    md64.md_data += ef->off;
+	} else if (error != 0)
+	    return (error);
 	md.md_version = md64.md_version;
 	md.md_type = md64.md_type;
-	md.md_cval = (const char *)(uintptr_t)(md64.md_cval + ef->off);
-	md.md_data = (void *)(uintptr_t)(md64.md_data + ef->off);
+	md.md_cval = (const char *)(uintptr_t)md64.md_cval;
+	md.md_data = (void *)(uintptr_t)md64.md_data;
 #else
 	COPYOUT(v, &md, sizeof(md));
-#ifdef __sparc64__
-	__elfN(reloc_ptr)(fp, ef, v, &md, sizeof(md));
-#else
-	md.md_cval += ef->off;
-	md.md_data += ef->off;
-#endif
+	error = __elfN(reloc_ptr)(fp, ef, v, &md, sizeof(md));
+	if (error == EOPNOTSUPP) {
+	    md.md_cval += ef->off;
+	    md.md_data += ef->off;
+	} else if (error != 0)
+	    return (error);
 #endif
 	p += sizeof(Elf_Addr);
 	switch(md.md_type) {
@@ -687,29 +700,53 @@ __elfN(lookup_symbol)(struct preloaded_file *fp, elf_file_t ef, const char* name
     return ENOENT;
 }
 
-#ifdef __sparc__
 /*
- * Apply any intra-module relocations to the value. *p is the load address
+ * Apply any intra-module relocations to the value. p is the load address
  * of the value and val/len is the value to be modified. This does NOT modify
  * the image in-place, because this is done by kern_linker later on.
+ *
+ * Returns EOPNOTSUPP if no relocation method is supplied.
  */
-static void
+static int
 __elfN(reloc_ptr)(struct preloaded_file *mp, elf_file_t ef,
-    void *p, void *val, size_t len)
+    Elf_Addr p, void *val, size_t len)
 {
-	Elf_Addr off = (Elf_Addr)p - ef->off, word;
 	size_t n;
-	Elf_Rela r;
+	Elf_Rela a;
+	Elf_Rel r;
+	int error;
 
-	for (n = 0; n < ef->relasz / sizeof(r); n++) {
-		COPYOUT(ef->rela + n, &r, sizeof(r));
+	/*
+	 * The kernel is already relocated, but we still want to apply
+	 * offset adjustments.
+	 */
+	if (ef->kernel)
+		return (EOPNOTSUPP);
 
-		if (r.r_offset >= off && r.r_offset < off + len &&
-		    ELF_R_TYPE(r.r_info) == R_SPARC_RELATIVE) {
-			word = ef->off + r.r_addend;
-			bcopy(&word, (char *)val + (r.r_offset - off),
-			    sizeof(word));
-		}
+	for (n = 0; n < ef->relsz / sizeof(r); n++) {
+		COPYOUT(ef->rel + n, &r, sizeof(r));
+
+		error = __elfN(reloc)(ef, __elfN(symaddr), &r, ELF_RELOC_REL,
+		    ef->off, p, val, len);
+		if (error != 0)
+			return (error);
 	}
+	for (n = 0; n < ef->relasz / sizeof(a); n++) {
+		COPYOUT(ef->rela + n, &a, sizeof(a));
+
+		error = __elfN(reloc)(ef, __elfN(symaddr), &a, ELF_RELOC_RELA,
+		    ef->off, p, val, len);
+		if (error != 0)
+			return (error);
+	}
+
+	return (0);
+}
+
+static Elf_Addr
+__elfN(symaddr)(struct elf_file *ef, Elf_Word symidx)
+{
+
+	/* Symbol lookup by index not required here. */
+	return (0);
 }
-#endif

sys/boot/common/reloc_elf.c

@@ -0,0 +1,199 @@
+/*-
+ * Copyright (c) 2003 Jake Burkholder.
+ * Copyright 1996-1998 John D. Polstra.
+ * Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
+ * Copyright (c) 1998 Peter Wemm <peter@freebsd.org>
+ * 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. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND 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 AUTHOR OR 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 <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/types.h>
+#include <machine/elf.h>
+
+#include <errno.h>
+#include <stand.h>
+
+#define FREEBSD_ELF
+#include <link.h>
+
+#include "bootstrap.h"
+
+#define COPYOUT(s,d,l)	archsw.arch_copyout((vm_offset_t)(s), d, l)
+
+/*
+ * Apply a single intra-module relocation to the data. `relbase' is the
+ * target relocation base for the section (i.e. it corresponds to where
+ * r_offset == 0). `dataaddr' is the relocated address corresponding to
+ * the start of the data, and `len' is the number of bytes.
+ */
+int
+__elfN(reloc)(struct elf_file *ef, symaddr_fn *symaddr, const void *reldata,
+    int reltype, Elf_Addr relbase, Elf_Addr dataaddr, void *data, size_t len)
+{
+#ifdef __sparc__
+	Elf_Word w;
+	const Elf_Rela *a;
+
+	switch (reltype) {
+	case ELF_RELOC_RELA:
+		a = reldata;
+		 if (relbase + a->r_offset >= dataaddr &&
+		     relbase + a->r_offset < dataaddr + len) {
+			switch (ELF_R_TYPE(a->r_info)) {
+			case R_SPARC_RELATIVE:
+				w = relbase + a->r_addend;
+				bcopy(&w, (u_char *)data + (relbase +
+				    a->r_offset - dataaddr), sizeof(w));
+				break;
+			default:
+				printf("\nunhandled relocation type %u\n",
+				    (u_int)ELF_R_TYPE(a->r_info));
+				return (EFTYPE);
+			}
+		}
+		break;
+	}
+
+	return (0);
+#elif defined(__i386__) && __ELF_WORD_SIZE == 64
+	Elf64_Addr *where, val;
+	Elf_Addr addend, addr;
+	Elf_Word rtype, symidx;
+	const Elf_Rel *rel;
+	const Elf_Rela *rela;
+
+	switch (reltype) {
+	case ELF_RELOC_REL:
+		rel = (const Elf_Rel *)reldata;
+		where = (Elf_Addr *)((char *)data + relbase + rel->r_offset -
+		    dataaddr);
+		addend = 0;
+		rtype = ELF_R_TYPE(rel->r_info);
+		symidx = ELF_R_SYM(rel->r_info);
+		addend = 0;
+		break;
+	case ELF_RELOC_RELA:
+		rela = (const Elf_Rela *)reldata;
+		where = (Elf_Addr *)((char *)data + relbase + rela->r_offset -
+		    dataaddr);
+		addend = rela->r_addend;
+		rtype = ELF_R_TYPE(rela->r_info);
+		symidx = ELF_R_SYM(rela->r_info);
+		break;
+	default:
+		return (EINVAL);
+	}
+
+	if ((char *)where < (char *)data || (char *)where >= (char *)data + len)
+		return (0);
+
+	if (reltype == ELF_RELOC_REL)
+		addend = *where;
+
+/* XXX, definitions not available on i386. */
+#define	R_X86_64_64		1
+#define	R_X86_64_RELATIVE	8
+
+	switch (rtype) {
+	case R_X86_64_64:		/* S + A */
+		addr = symaddr(ef, symidx);
+		if (addr == 0)
+			return (ESRCH);
+		val = addr + addend;
+		*where = val;
+		break;
+	case R_X86_64_RELATIVE:
+		addr = (Elf_Addr)addend + relbase;
+		val = addr;
+		*where = val;
+		break;
+	default:
+		printf("\nunhandled relocation type %u\n", (u_int)rtype);
+		return (EFTYPE);
+	}
+
+	return (0);
+#elif defined(__i386__) && __ELF_WORD_SIZE == 32
+	Elf_Addr addend, addr, *where, val;
+	Elf_Word rtype, symidx;
+	const Elf_Rel *rel;
+	const Elf_Rela *rela;
+
+	switch (reltype) {
+	case ELF_RELOC_REL:
+		rel = (const Elf_Rel *)reldata;
+		where = (Elf_Addr *)((char *)data + relbase + rel->r_offset -
+		    dataaddr);
+		addend = 0;
+		rtype = ELF_R_TYPE(rel->r_info);
+		symidx = ELF_R_SYM(rel->r_info);
+		addend = 0;
+		break;
+	case ELF_RELOC_RELA:
+		rela = (const Elf_Rela *)reldata;
+		where = (Elf_Addr *)((char *)data + relbase + rela->r_offset -
+		    dataaddr);
+		addend = rela->r_addend;
+		rtype = ELF_R_TYPE(rela->r_info);
+		symidx = ELF_R_SYM(rela->r_info);
+		break;
+	default:
+		return (EINVAL);
+	}
+
+	if ((char *)where < (char *)data || (char *)where >= (char *)data + len)
+		return (0);
+
+	if (reltype == ELF_RELOC_REL)
+		addend = *where;
+
+/* XXX, definitions not available on amd64. */
+#define R_386_32	1	/* Add symbol value. */
+#define R_386_GLOB_DAT	6	/* Set GOT entry to data address. */
+#define R_386_RELATIVE	8	/* Add load address of shared object. */
+
+	switch (rtype) {
+	case R_386_RELATIVE:
+		addr = addend + relbase;
+		*where = addr;
+		break;
+	case R_386_32:		/* S + A */
+		addr = symaddr(ef, symidx);
+		if (addr == 0)
+			return (ESRCH);
+		val = addr + addend;
+		*where = val;
+		break;
+	default:
+		printf("\nunhandled relocation type %u\n", (u_int)rtype);
+		return (EFTYPE);
+	}
+
+	return (0);
+#else
+	return (EOPNOTSUPP);
+#endif
+}

sys/boot/common/reloc_elf32.c

@@ -0,0 +1,6 @@
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#define __ELF_WORD_SIZE 32
+
+#include "reloc_elf.c"

sys/boot/common/reloc_elf64.c

@@ -0,0 +1,6 @@
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#define __ELF_WORD_SIZE 64
+
+#include "reloc_elf.c"