Re: Linux Module broken

[Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>]

:kldload: can't load linux.ko: Exec format error
:link_elf: symbol globaldata not found
:
:Rob

    Hmm.  How odd.   The ELF loader is assuming that symbols with values
    of 0 are the same as not finding the symbol, or that they are common
    symbols when they could be absolute symbols (globaldata is an absolute
    symbol with a value of 0).

    Please try this patch.  It's unfortunately rather involved because
    the ELF loader is making all sorts of assumptions that it shouldn't
    be making, and I haven't completely fixed it due to an opaque structure,
    but it should handle absolute symbols properly now.

					-Matt
					Matthew Dillon 
					<dillon@xxxxxxxxxxxxx>

Index: i386/i386/elf_machdep.c
===================================================================
RCS file: /cvs/src/sys/i386/i386/elf_machdep.c,v
retrieving revision 1.2
diff -u -r1.2 elf_machdep.c
--- i386/i386/elf_machdep.c	17 Jun 2003 04:28:35 -0000	1.2
+++ i386/i386/elf_machdep.c	17 Jul 2003 23:21:47 -0000
@@ -40,6 +40,7 @@
 	Elf_Addr addr;
 	Elf_Addr addend;
 	Elf_Word rtype;
+	caddr_t caddr;
 	const Elf_Rel *rel;
 	const Elf_Rela *rela;
 
@@ -68,9 +69,9 @@
 		case R_386_32:		/* S + A */
 			if (sym == NULL)
 				return -1;
-			addr = (Elf_Addr)linker_file_lookup_symbol(lf, sym, 1);
-			if (addr == 0)
+			if (linker_file_lookup_symbol(lf, sym, 1, &caddr) != 0)
 				return -1;
+			addr = (Elf_Addr)caddr;
 			addr += addend;
 			if (*where != addr)
 				*where = addr;
@@ -79,9 +80,9 @@
 		case R_386_PC32:	/* S + A - P */
 			if (sym == NULL)
 				return -1;
-			addr = (Elf_Addr)linker_file_lookup_symbol(lf, sym, 1);
-			if (addr == 0)
+			if (linker_file_lookup_symbol(lf, sym, 1, &caddr) != 0)
 				return -1;
+			addr = (Elf_Addr)caddr;
 			addr += addend - (Elf_Addr)where;
 			if (*where != addr)
 				*where = addr;
@@ -99,9 +100,9 @@
 		case R_386_GLOB_DAT:	/* S */
 			if (sym == NULL)
 				return -1;
-			addr = (Elf_Addr)linker_file_lookup_symbol(lf, sym, 1);
-			if (addr == 0)
+			if (linker_file_lookup_symbol(lf, sym, 1, &caddr) != 0)
 				return -1;
+			addr = (Elf_Addr)caddr;
 			if (*where != addr)
 				*where = addr;
 			break;
Index: kern/kern_linker.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_linker.c,v
retrieving revision 1.6
diff -u -r1.6 kern_linker.c
--- kern/kern_linker.c	27 Jun 2003 01:53:25 -0000	1.6
+++ kern/kern_linker.c	17 Jul 2003 23:21:47 -0000
@@ -102,11 +102,12 @@
     KLD_DPF(FILE, ("linker_file_sysinit: calling SYSINITs for %s\n",
 		   lf->filename));
 
-    sysinits = (struct linker_set*)
-	linker_file_lookup_symbol(lf, "sysinit_set", 0);
-
+    if (linker_file_lookup_symbol(lf, "sysinit_set", 0, (caddr_t *)&sysinits)) {
+	KLD_DPF(FILE, ("linker_file_sysinit: SYSINITs not found\n"));
+	return 0; /* XXX is this correct ? No sysinit ? */
+    }
     KLD_DPF(FILE, ("linker_file_sysinit: SYSINITs %p\n", sysinits));
-    if (!sysinits)
+    if (sysinits == NULL)
 	return 0; /* XXX is this correct ? No sysinit ? */
 
     /* HACK ALERT! */
@@ -167,11 +168,12 @@
     KLD_DPF(FILE, ("linker_file_sysuninit: calling SYSUNINITs for %s\n",
 		   lf->filename));
 
-    sysuninits = (struct linker_set*)
-	linker_file_lookup_symbol(lf, "sysuninit_set", 0);
-
+    if (linker_file_lookup_symbol(lf, "sysuninit_set", 0, (caddr_t *)&sysuninits)) {
+	KLD_DPF(FILE, ("linker_file_sysuninit: SYSUNINITs not found\n"));
+	return;
+    }
     KLD_DPF(FILE, ("linker_file_sysuninit: SYSUNINITs %p\n", sysuninits));
-    if (!sysuninits)
+    if (sysuninits == NULL)
 	return;
 
     /*
@@ -215,11 +217,12 @@
     KLD_DPF(FILE, ("linker_file_register_sysctls: registering SYSCTLs for %s\n",
 		   lf->filename));
 
-    sysctls = (struct linker_set*)
-	linker_file_lookup_symbol(lf, "sysctl_set", 0);
-
+    if (linker_file_lookup_symbol(lf, "sysctl_set", 0, (caddr_t *)&sysctls)) {
+	KLD_DPF(FILE, ("linker_file_register_sysctls: SYSCTLs not found\n"));
+	return;
+    }
     KLD_DPF(FILE, ("linker_file_register_sysctls: SYSCTLs %p\n", sysctls));
-    if (!sysctls)
+    if (sysctls == NULL)
 	return;
 
     sysctl_register_set(sysctls);
@@ -233,11 +236,12 @@
     KLD_DPF(FILE, ("linker_file_unregister_sysctls: registering SYSCTLs for %s\n",
 		   lf->filename));
 
-    sysctls = (struct linker_set*)
-	linker_file_lookup_symbol(lf, "sysctl_set", 0);
-
+    if (linker_file_lookup_symbol(lf, "sysctl_set", 0, (caddr_t *)&sysctls)) {
+	KLD_DPF(FILE, ("linker_file_unregister_sysctls: SYSCTLs not found\n"));
+	return;
+    }
     KLD_DPF(FILE, ("linker_file_unregister_sysctls: SYSCTLs %p\n", sysctls));
-    if (!sysctls)
+    if (sysctls == NULL)
 	return;
 
     sysctl_unregister_set(sysctls);
@@ -478,13 +482,12 @@
     return 0;
 }
 
-caddr_t
-linker_file_lookup_symbol(linker_file_t file, const char* name, int deps)
+int
+linker_file_lookup_symbol(linker_file_t file, const char* name, int deps, caddr_t *raddr)
 {
     c_linker_sym_t sym;
     linker_symval_t symval;
     linker_file_t lf;
-    caddr_t address;
     size_t common_size = 0;
     int i;
 
@@ -493,24 +496,28 @@
 
     if (file->ops->lookup_symbol(file, name, &sym) == 0) {
 	file->ops->symbol_values(file, sym, &symval);
-	if (symval.value == 0)
+
+	/*
+	 * XXX Assume a common symbol if its value is 0 and it has a non-zero
+	 * size, otherwise it could be an absolute symbol with a value of 0.
+	 */
+	if (symval.value == 0 && symval.size != 0) {
 	    /*
 	     * For commons, first look them up in the dependancies and
 	     * only allocate space if not found there.
 	     */
 	    common_size = symval.size;
-	else {
+	} else {
 	    KLD_DPF(SYM, ("linker_file_lookup_symbol: symbol.value=%x\n", symval.value));
-	    return symval.value;
+	    *raddr = symval.value;
+	    return 0;
 	}
     }
-
     if (deps) {
 	for (i = 0; i < file->ndeps; i++) {
-	    address = linker_file_lookup_symbol(file->deps[i], name, 0);
-	    if (address) {
-		KLD_DPF(SYM, ("linker_file_lookup_symbol: deps value=%x\n", address));
-		return address;
+	    if (linker_file_lookup_symbol(file->deps[i], name, 0, raddr) == 0) {
+		KLD_DPF(SYM, ("linker_file_lookup_symbol: deps value=%x\n", *raddr));
+		return 0;
 	    }
 	}
 
@@ -525,10 +532,9 @@
 		    break;
 	    if (i < file->ndeps)
 		continue;
-	    address = linker_file_lookup_symbol(lf, name, 0);
-	    if (address) {
-		KLD_DPF(SYM, ("linker_file_lookup_symbol: global value=%x\n", address));
-		return address;
+	    if (linker_file_lookup_symbol(lf, name, 0, raddr) == 0) {
+		KLD_DPF(SYM, ("linker_file_lookup_symbol: global value=%x\n", *raddr));
+		return 0;
 	    }
 	}
     }
@@ -545,7 +551,8 @@
 	     cp = STAILQ_NEXT(cp, link))
 	    if (!strcmp(cp->name, name)) {
 		KLD_DPF(SYM, ("linker_file_lookup_symbol: old common value=%x\n", cp->address));
-		return cp->address;
+		*raddr = cp->address;
+		return 0;
 	    }
 
 	/*
@@ -558,7 +565,7 @@
 		    M_LINKER, M_WAITOK);
 	if (!cp) {
 	    KLD_DPF(SYM, ("linker_file_lookup_symbol: nomem\n"));
-	    return 0;
+	    return ENOMEM;
 	}
 	bzero(cp, sizeof(struct common_symbol) + common_size + strlen(name)+ 1);
 
@@ -569,11 +576,12 @@
 	STAILQ_INSERT_TAIL(&file->common, cp, link);
 
 	KLD_DPF(SYM, ("linker_file_lookup_symbol: new common value=%x\n", cp->address));
-	return cp->address;
+	*raddr = cp->address;
+	return 0;
     }
 
     KLD_DPF(SYM, ("linker_file_lookup_symbol: fail\n"));
-    return 0;
+    return ENOENT;
 }
 
 #ifdef DDB
@@ -947,9 +955,7 @@
 	if (lf) {
 	    lf->userrefs++;
 
-	    sysinits = (struct linker_set*)
-		linker_file_lookup_symbol(lf, "sysinit_set", 0);
-	    if (sysinits) {
+	    if (linker_file_lookup_symbol(lf, "sysinit_set", 0, (caddr_t *)&sysinits) == 0 && sysinits) {
 		/* HACK ALERT!
 		 * This is to set the sysinit moduledata so that the module
 		 * can attach itself to the correct containing file.
Index: kern/link_aout.c
===================================================================
RCS file: /cvs/src/sys/kern/link_aout.c,v
retrieving revision 1.4
diff -u -r1.4 link_aout.c
--- kern/link_aout.c	26 Jun 2003 05:55:14 -0000	1.4
+++ kern/link_aout.c	17 Jul 2003 23:21:47 -0000
@@ -408,14 +408,14 @@
 
 	    if (sym[0] != '_') {
 		printf("link_aout: bad symbol name %s\n", sym);
-		relocation = 0;
-	    } else
-		relocation = (intptr_t)
-		    linker_file_lookup_symbol(lf, sym + 1,
-					      np->nz_type != (N_SETV+N_EXT));
-	    if (!relocation) {
 		printf("link_aout: symbol %s not found\n", sym);
 		return ENOENT;
+	    } else {
+		if (linker_file_lookup_symbol(lf, sym + 1,
+		    (np->nz_type != (N_SETV+N_EXT)), (caddr_t *)&relocation)) {
+			printf("link_aout: symbol %s not found\n", sym);
+			return ENOENT;
+		}
 	    }
 	    
 	    relocation += read_relocation(r, addr);
Index: kern/link_elf.c
===================================================================
RCS file: /cvs/src/sys/kern/link_elf.c,v
retrieving revision 1.4
diff -u -r1.4 link_elf.c
--- kern/link_elf.c	26 Jun 2003 05:55:14 -0000	1.4
+++ kern/link_elf.c	17 Jul 2003 23:21:47 -0000
@@ -896,11 +896,13 @@
 	if (strcmp(name, strp) == 0) {
 	    if (symp->st_shndx != SHN_UNDEF ||
 		(symp->st_value != 0 &&
-		 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
+		 ELF_ST_TYPE(symp->st_info) == STT_FUNC)
+	     ) {
 		*sym = (c_linker_sym_t) symp;
 		return 0;
-	    } else
+	    } else {
 		return ENOENT;
+	    }
 	}
 
 	symnum = ef->chains[symnum];
@@ -919,11 +921,11 @@
 		 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) {
 		*sym = (c_linker_sym_t) symp;
 		return 0;
-	    } else
+	    } else {
 		return ENOENT;
+	    }
 	}
     }
-
     return ENOENT;
 }
 
Index: sys/linker.h
===================================================================
RCS file: /cvs/src/sys/sys/linker.h,v
retrieving revision 1.2
diff -u -r1.2 linker.h
--- sys/linker.h	17 Jun 2003 04:28:58 -0000	1.2
+++ sys/linker.h	17 Jul 2003 23:21:47 -0000
@@ -180,10 +180,11 @@
 
 /*
  * Lookup a symbol in a file.  If deps is TRUE, look in dependancies
- * if not found in file.
+ * if not found in file.  The symbol's value is returned in the
+ * caddr_t.  An error is returned, 0 if no error occured.
  */
-caddr_t linker_file_lookup_symbol(linker_file_t _file, const char* _name, 
-				  int _deps);
+int linker_file_lookup_symbol(linker_file_t _file, const char* _name, 
+				  int _deps, caddr_t *);
 
 /*
  * Search the linker path for the module.  Return the full pathname in