Explicitly pass in the relocation base and data offset into ef_reloc()

rather than relying on a trick that happens to work for the current
relocation schemes. Also add some comments and improve variable
naming.

7 files changed, 54 insertions, 43 deletions

diff --git a/usr.sbin/kldxref/ef.c b/usr.sbin/kldxref/ef.c
index 55efb53..c6751c9 100644
--- a/usr.sbin/kldxref/ef.c
+++ b/usr.sbin/kldxref/ef.c
@@ -481,13 +481,13 @@ ef_seg_read_rel(elf_file_t ef, Elf_Off offset, size_t len, void*dest)
 		return (error);
 
 	for (r = ef->ef_rel; r < &ef->ef_rel[ef->ef_relsz]; r++) {
-		error = ef_reloc(ef->ef_efile, r, EF_RELOC_REL, offset, len,
+		error = ef_reloc(ef->ef_efile, r, EF_RELOC_REL, 0, offset, len,
 		    dest);
 		if (error != 0)
 			return (error);
 	}
 	for (a = ef->ef_rela; a < &ef->ef_rela[ef->ef_relasz]; a++) {
-		error = ef_reloc(ef->ef_efile, a, EF_RELOC_RELA, offset, len,
+		error = ef_reloc(ef->ef_efile, a, EF_RELOC_RELA, 0, offset, len,
 		    dest);
 		if (error != 0)
 			return (error);
diff --git a/usr.sbin/kldxref/ef.h b/usr.sbin/kldxref/ef.h
index 6a5a627..3843ebe 100644
--- a/usr.sbin/kldxref/ef.h
+++ b/usr.sbin/kldxref/ef.h
@@ -62,8 +62,8 @@ struct elf_file {
 __BEGIN_DECLS
 int ef_open(const char *filename, struct elf_file *ef, int verbose);
 int ef_obj_open(const char *filename, struct elf_file *ef, int verbose);
-int ef_reloc(struct elf_file *ef, const void *data, int type, Elf_Off offset,
-    size_t len, void *dest);
+int ef_reloc(struct elf_file *ef, const void *reldata, int reltype,
+    Elf_Off relbase, Elf_Off dataoff, size_t len, void *dest);
 __END_DECLS
 
 #endif /* _EF_H_*/
diff --git a/usr.sbin/kldxref/ef_amd64.c b/usr.sbin/kldxref/ef_amd64.c
index f0acba8..445640a 100644
--- a/usr.sbin/kldxref/ef_amd64.c
+++ b/usr.sbin/kldxref/ef_amd64.c
@@ -37,11 +37,13 @@
 #include "ef.h"
 
 /*
- * Apply relocations to the values we got from the file.
+ * Apply relocations to the values we got from the file. `relbase' is the
+ * target relocation address of the section, and `dataoff' is the target
+ * relocation address of the data in `dest'.
  */
 int
-ef_reloc(struct elf_file *ef, const void *data, int type, Elf_Off offset,
-    size_t len, void *dest)
+ef_reloc(struct elf_file *ef, const void *reldata, int reltype, Elf_Off relbase,
+    Elf_Off dataoff, size_t len, void *dest)
 {
 	Elf64_Addr *where, val;
 	Elf32_Addr *where32, val32;
@@ -50,16 +52,17 @@ ef_reloc(struct elf_file *ef, const void *data, int type, Elf_Off offset,
 	const Elf_Rel *rel;
 	const Elf_Rela *rela;
 
-	switch (type) {
+	switch (reltype) {
 	case EF_RELOC_REL:
-		rel = (const Elf_Rel *)data;
-		where = (Elf_Addr *)(dest + rel->r_offset - offset);
+		rel = (const Elf_Rel *)reldata;
+		where = (Elf_Addr *)(dest + relbase + rel->r_offset - dataoff);
+		addend = 0;
 		rtype = ELF_R_TYPE(rel->r_info);
 		symidx = ELF_R_SYM(rel->r_info);
 		break;
 	case EF_RELOC_RELA:
-		rela = (const Elf_Rela *)data;
-		where = (Elf_Addr *)(dest + rela->r_offset - offset);
+		rela = (const Elf_Rela *)reldata;
+		where = (Elf_Addr *)(dest + relbase + rela->r_offset - dataoff);
 		addend = rela->r_addend;
 		rtype = ELF_R_TYPE(rela->r_info);
 		symidx = ELF_R_SYM(rela->r_info);
@@ -71,7 +74,7 @@ ef_reloc(struct elf_file *ef, const void *data, int type, Elf_Off offset,
 	if ((char *)where < (char *)dest || (char *)where >= (char *)dest + len)
 		return (0);
 
-	if (type == EF_RELOC_REL) {
+	if (reltype == EF_RELOC_REL) {
 		/* Addend is 32 bit on 32 bit relocs */
 		switch (rtype) {
 		case R_X86_64_PC32:
@@ -103,7 +106,7 @@ ef_reloc(struct elf_file *ef, const void *data, int type, Elf_Off offset,
 		*where = addr;
 		break;
 	case R_X86_64_RELATIVE:	/* B + A */
-		addr = (Elf_Addr)addend;
+		addr = (Elf_Addr)addend + relbase;
 		val = addr;
 		*where = val;
 		break;
diff --git a/usr.sbin/kldxref/ef_i386.c b/usr.sbin/kldxref/ef_i386.c
index 9735900..0fc726a 100644
--- a/usr.sbin/kldxref/ef_i386.c
+++ b/usr.sbin/kldxref/ef_i386.c
@@ -37,27 +37,30 @@
 #include "ef.h"
 
 /*
- * Apply relocations to the values we got from the file.
+ * Apply relocations to the values we got from the file. `relbase' is the
+ * target relocation address of the section, and `dataoff' is the target
+ * relocation address of the data in `dest'.
  */
 int
-ef_reloc(struct elf_file *ef, const void *data, int type, Elf_Off offset,
-    size_t len, void *dest)
+ef_reloc(struct elf_file *ef, const void *reldata, int reltype, Elf_Off relbase,
+    Elf_Off dataoff, size_t len, void *dest)
 {
 	Elf_Addr *where, addr, addend;
 	Elf_Word rtype, symidx;
 	const Elf_Rel *rel;
 	const Elf_Rela *rela;
 
-	switch (type) {
+	switch (reltype) {
 	case EF_RELOC_REL:
-		rel = (const Elf_Rel *)data;
-		where = (Elf_Addr *)(dest + rel->r_offset - offset);
+		rel = (const Elf_Rel *)reldata;
+		where = (Elf_Addr *)(dest + relbase + rel->r_offset - dataoff);
+		addend = 0;
 		rtype = ELF_R_TYPE(rel->r_info);
 		symidx = ELF_R_SYM(rel->r_info);
 		break;
 	case EF_RELOC_RELA:
-		rela = (const Elf_Rela *)data;
-		where = (Elf_Addr *)(dest + rela->r_offset - offset);
+		rela = (const Elf_Rela *)reldata;
+		where = (Elf_Addr *)(dest + relbase + rela->r_offset - dataoff);
 		addend = rela->r_addend;
 		rtype = ELF_R_TYPE(rela->r_info);
 		symidx = ELF_R_SYM(rela->r_info);
@@ -69,12 +72,12 @@ ef_reloc(struct elf_file *ef, const void *data, int type, Elf_Off offset,
 	if ((char *)where < (char *)dest || (char *)where >= (char *)dest + len)
 		return (0);
 
-	if (type == EF_RELOC_REL)
+	if (reltype == EF_RELOC_REL)
 		addend = *where;
 
 	switch (rtype) {
 	case R_386_RELATIVE:	/* A + B */
-		addr = (Elf_Addr)addend;
+		addr = (Elf_Addr)addend + relbase;
 		*where = addr;
 		break;
 	case R_386_32:	/* S + A - P */
diff --git a/usr.sbin/kldxref/ef_nop.c b/usr.sbin/kldxref/ef_nop.c
index b1a798b..cbbd43c 100644
--- a/usr.sbin/kldxref/ef_nop.c
+++ b/usr.sbin/kldxref/ef_nop.c
@@ -32,8 +32,8 @@
 #include "ef.h"
 
 int
-ef_reloc(struct elf_file *ef, const void *data, int type, Elf_Off offset,
-    size_t len, void *dest)
+ef_reloc(struct elf_file *ef, const void *reldata, int reltype, Elf_Off relbase,
+    Elf_Off dataoff, size_t len, void *dest)
 {
 
 	return (0);
diff --git a/usr.sbin/kldxref/ef_obj.c b/usr.sbin/kldxref/ef_obj.c
index 884a1b3..3ed4e40 100644
--- a/usr.sbin/kldxref/ef_obj.c
+++ b/usr.sbin/kldxref/ef_obj.c
@@ -240,9 +240,9 @@ ef_obj_seg_read_rel(elf_file_t ef, Elf_Off offset, size_t len, void *dest)
 	char *memaddr;
 	Elf_Rel *r;
 	Elf_Rela *a;
-	Elf_Off secoff;
+	Elf_Off secbase, dataoff;
 	int error, i, sec;
-	
+
 	if (offset + len > ef->size) {
 		if (ef->ef_verbose)
 			warnx("ef_seg_read_rel(%s): bad offset/len (%lx:%ld)",
@@ -254,6 +254,7 @@ ef_obj_seg_read_rel(elf_file_t ef, Elf_Off offset, size_t len, void *dest)
 	/* Find out which section contains the data. */
 	memaddr = ef->address + offset;
 	sec = -1;
+	secbase = dataoff = 0;
 	for (i = 0; i < ef->nprogtab; i++) {
 		if (ef->progtab[i].addr == NULL)
 			continue;
@@ -261,7 +262,9 @@ ef_obj_seg_read_rel(elf_file_t ef, Elf_Off offset, size_t len, void *dest)
 		     (char *)ef->progtab[i].addr + ef->progtab[i].size)
 			continue;
 		sec = ef->progtab[i].sec;
-		secoff = memaddr - (char *)ef->progtab[i].addr;
+		/* We relocate to address 0. */
+		secbase = (char *)ef->progtab[i].addr - ef->address;
+		dataoff = memaddr - ef->address;
 		break;
 	}
 
@@ -274,8 +277,8 @@ ef_obj_seg_read_rel(elf_file_t ef, Elf_Off offset, size_t len, void *dest)
 			continue;
 		for (r = ef->reltab[i].rel;
 		     r < &ef->reltab[i].rel[ef->reltab[i].nrel]; r++) {
-			error = ef_reloc(ef->ef_efile, r, EF_RELOC_REL, secoff,
-			    len, dest);
+			error = ef_reloc(ef->ef_efile, r, EF_RELOC_REL, secbase,
+			    dataoff, len, dest);
 			if (error != 0)
 				return (error);
 		}
@@ -285,8 +288,8 @@ ef_obj_seg_read_rel(elf_file_t ef, Elf_Off offset, size_t len, void *dest)
 			continue;
 		for (a = ef->relatab[i].rela;
 		     a < &ef->relatab[i].rela[ef->relatab[i].nrela]; a++) {
-			error = ef_reloc(ef->ef_efile, a, EF_RELOC_RELA, secoff,
-			    len, dest);
+			error = ef_reloc(ef->ef_efile, a, EF_RELOC_RELA,
+			    secbase, dataoff, len, dest);
 			if (error != 0)
 				return (error);
 		}
diff --git a/usr.sbin/kldxref/ef_sparc64.c b/usr.sbin/kldxref/ef_sparc64.c
index 78b40db..e5133f1 100644
--- a/usr.sbin/kldxref/ef_sparc64.c
+++ b/usr.sbin/kldxref/ef_sparc64.c
@@ -35,25 +35,27 @@
 #include "ef.h"
 
 /*
- * Apply relocations to the values we got from the file.
+ * Apply relocations to the values we got from the file. `relbase' is the
+ * target relocation address of the section, and `dataoff' is the target
+ * relocation address of the data in `dest'.
  */
 int
-ef_reloc(struct elf_file *ef, const void *data, int type, Elf_Off offset,
-    size_t len, void *dest)
+ef_reloc(struct elf_file *ef, const void *reldata, int reltype, Elf_Off relbase,
+    Elf_Off dataoff, size_t len, void *dest)
 {
 	const Elf_Rela *a;
 	Elf_Word w;
 
-	switch (type) {
+	switch (reltype) {
 	case EF_RELOC_RELA:
-		a = data;
-		if (a->r_offset >= offset && a->r_offset < offset + len) {
+		a = reldata;
+		if (relbase + a->r_offset >= dataoff && relbase + a->r_offset <
+		    dataoff + len) {
 			switch (ELF_R_TYPE(a->r_info)) {
 			case R_SPARC_RELATIVE:
-				/* load address is 0 */
-				w = a->r_addend;
-				memcpy((u_char *)dest + (a->r_offset - offset),
-				    &w, sizeof(w));
+				w = a->r_addend + relbase;
+				memcpy((u_char *)dest + (relbase + a->r_offset -
+				    dataoff), &w, sizeof(w));
 				break;
 			default:
 				warnx("unhandled relocation type %u",