ELF handling patch

[Joerg Sonnenberger <joerg@xxxxxxxxxxxxxxxxx>]

Hi all,
please test the attached carefully. It's an important step for better
OS emulation support. brandelf should no longer be necessary, not even
for static Linux binaries. There's still a lot room for improvements :)

Joerg

Index: kern/imgact_elf.c
===================================================================
RCS file: /home/joerg/wd/repository/dragonflybsd/src/sys/kern/imgact_elf.c,v
retrieving revision 1.26
diff -u -r1.26 imgact_elf.c
--- kern/imgact_elf.c	8 Mar 2005 12:30:32 -0000	1.26
+++ kern/imgact_elf.c	30 May 2005 15:42:58 -0000
@@ -87,6 +87,9 @@
 SYSCTL_INT(_debug, OID_AUTO, elf_legacy_coredump, CTLFLAG_RW,
     &elf_legacy_coredump, 0, "");
 
+static int dragonfly_match_abi_note(const Elf_Note *);
+static int freebsd_match_abi_note(const Elf_Note *);
+
 static struct sysentvec elf_freebsd_sysvec = {
         SYS_MAXSYSCALL,
         sysent,
@@ -110,16 +113,54 @@
 static Elf_Brandinfo freebsd_brand_info = {
 						ELFOSABI_FREEBSD,
 						"FreeBSD",
+						freebsd_match_abi_note,
 						"",
 						"/usr/libexec/ld-elf.so.1",
 						&elf_freebsd_sysvec
 					  };
+
+static Elf_Brandinfo dragonfly_brand_info = {
+						ELFOSABI_NONE,
+						"DragonFly",
+						dragonfly_match_abi_note,
+						"",
+						"/usr/libexec/ld-elf.so.2",
+						&elf_freebsd_sysvec
+					  };
+
 static Elf_Brandinfo *elf_brand_list[MAX_BRANDS] = {
+							&dragonfly_brand_info,
 							&freebsd_brand_info,
 							NULL, NULL, NULL,
-							NULL, NULL, NULL, NULL
+							NULL, NULL, NULL
 						    };
 
+static int
+freebsd_match_abi_note(const Elf_Note *abi_note)
+{
+	const char *abi_name = (const char *)
+	    ((const uint8_t *)abi_note + sizeof(*abi_note));
+
+	if (abi_note->n_namesz < sizeof("FreeBSD"))
+		return(0);
+	if (memcmp(abi_name, "FreeBSD", sizeof("FreeBSD")))
+		return(0);
+	return(1);
+}
+
+static int
+dragonfly_match_abi_note(const Elf_Note *abi_note)
+{
+	const char *abi_name = (const char *)
+	    ((const uint8_t *)abi_note + sizeof(*abi_note));
+
+	if (abi_note->n_namesz < sizeof("DragonFly"))
+		return(0);
+	if (memcmp(abi_name, "DragonFly", sizeof("DragonFly")))
+		return(0);
+	return(1);
+}
+
 int
 elf_insert_brand_entry(Elf_Brandinfo *entry)
 {
@@ -483,6 +524,7 @@
 	u_long addr, entry = 0, proghdr = 0;
 	int error, i;
 	const char *interp = NULL;
+	const Elf_Note *abi_note = NULL;
 	Elf_Brandinfo *brand_info;
 	char *path;
 
@@ -606,6 +648,23 @@
 			}
 			interp = imgp->image_header + phdr[i].p_offset;
 			break;
+		case PT_NOTE:	/* Check for .note.ABI-tag */
+		{
+			const Elf_Note *tmp_note;
+			/* XXX handle anything outside the first page */
+			if (phdr[i].p_offset + phdr[i].p_filesz > PAGE_SIZE)
+				continue;
+			if (phdr[i].p_filesz < sizeof(Elf_Note))
+				continue; /* ENOEXEC? */
+			tmp_note = (const Elf_Note *)(imgp->image_header + phdr[i].p_offset);
+			if (tmp_note->n_type != 1)
+				continue;
+			if (tmp_note->n_namesz + sizeof(Elf_Note) +
+			    tmp_note->n_descsz > phdr[i].p_filesz)
+				continue; /* ENOEXEC? */
+			abi_note = tmp_note;
+		}	
+			break;
 		case PT_PHDR: 	/* Program header table info */
 			proghdr = phdr[i].p_vaddr;
 			break;
@@ -633,7 +692,7 @@
 	 */
 
 	/* If the executable has a brand, search for it in the brand list. */
-	if (brand_info == NULL) {
+	if (brand_info == NULL && hdr->e_ident[EI_OSABI] != ELFOSABI_NONE) {
 		for (i = 0;  i < MAX_BRANDS;  i++) {
 			Elf_Brandinfo *bi = elf_brand_list[i];
 
@@ -648,7 +707,20 @@
 		}
 	}
 
-	/* Lacking a known brand, search for a recognized interpreter. */
+	/* Search for a recognized ABI. */
+	if (brand_info == NULL && abi_note != NULL) {
+		for (i = 0; i < MAX_BRANDS; i++) {
+			Elf_Brandinfo *bi = elf_brand_list[i];
+
+			if (bi != NULL && bi->match_abi_note != NULL
+			    && (*bi->match_abi_note)(abi_note)) {
+				brand_info = bi;
+				break;
+			}
+		}
+	}
+
+	/* Lacking a recognized ABI, search for a recognized interpreter. */
 	if (brand_info == NULL && interp != NULL) {
 		for (i = 0;  i < MAX_BRANDS;  i++) {
 			Elf_Brandinfo *bi = elf_brand_list[i];
@@ -678,7 +750,7 @@
 		    hdr->e_ident[EI_OSABI]);
 		error = ENOEXEC;
 		goto fail;
-	}
+	} else
 
 	imgp->proc->p_sysent = brand_info->sysvec;
 	if (interp != NULL) {
Index: emulation/linux/i386/linux_sysvec.c
===================================================================
RCS file: /home/joerg/wd/repository/dragonflybsd/src/sys/emulation/linux/i386/linux_sysvec.c,v
retrieving revision 1.16
diff -u -r1.16 linux_sysvec.c
--- emulation/linux/i386/linux_sysvec.c	15 Aug 2004 14:15:00 -0000	1.16
+++ emulation/linux/i386/linux_sysvec.c	30 May 2005 14:17:06 -0000
@@ -793,9 +793,12 @@
 	LINUX_MINSIGSTKSZ
 };
 
+static int	linux_match_abi_note(const Elf_Note *abi_note);
+
 static Elf32_Brandinfo linux_brand = {
 					ELFOSABI_LINUX,
 					"Linux",
+					linux_match_abi_note,
 					"/compat/linux",
 					"/lib/ld-linux.so.1",
 					&elf_linux_sysvec
@@ -804,6 +807,7 @@
 static Elf32_Brandinfo linux_glibc2brand = {
 					ELFOSABI_LINUX,
 					"Linux",
+					linux_match_abi_note,
 					"/compat/linux",
 					"/lib/ld-linux.so.2",
 					&elf_linux_sysvec
@@ -816,6 +820,26 @@
 				};
 
 static int
+linux_match_abi_note(const Elf_Note *abi_note)
+{
+	const char *abi_name = (const char *)
+	    ((const uint8_t *)abi_note + sizeof(*abi_note));
+	const uint32_t *descr = (const uint32_t *)
+	    ((const uint8_t *)abi_name + abi_note->n_namesz);
+
+	if (abi_note->n_namesz < sizeof("GNU"))
+		return(0);
+	if (memcmp(abi_name, "GNU", sizeof("GNU")))
+		return(0);
+	if (abi_note->n_descsz < sizeof(uint32_t))
+		return(0);
+
+	if (*descr != 0)
+		return(0);
+	return(1);
+}
+
+static int
 linux_elf_modevent(module_t mod, int type, void *data)
 {
 	Elf32_Brandinfo **brandinfo;
Index: emulation/svr4/svr4_sysvec.c
===================================================================
RCS file: /home/joerg/wd/repository/dragonflybsd/src/sys/emulation/svr4/svr4_sysvec.c,v
retrieving revision 1.11
diff -u -r1.11 svr4_sysvec.c
--- emulation/svr4/svr4_sysvec.c	12 Nov 2004 00:09:22 -0000	1.11
+++ emulation/svr4/svr4_sysvec.c	30 May 2005 15:24:27 -0000
@@ -190,6 +190,7 @@
 Elf32_Brandinfo svr4_brand = {
   ELFOSABI_SYSV,
   "SVR4",
+  NULL,
   "/compat/svr4",
   "/lib/libc.so.1",
   &svr4_sysvec
Index: sys/imgact_elf.h
===================================================================
RCS file: /home/joerg/wd/repository/dragonflybsd/src/sys/sys/imgact_elf.h,v
retrieving revision 1.5
diff -u -r1.5 imgact_elf.h
--- sys/imgact_elf.h	25 Oct 2004 08:57:50 -0000	1.5
+++ sys/imgact_elf.h	30 May 2005 13:39:26 -0000
@@ -32,6 +32,7 @@
 #ifndef _SYS_IMGACT_ELF_H_
 #define _SYS_IMGACT_ELF_H_
 
+#include <sys/elf_common.h>
 #include <machine/elf.h>
 
 #ifdef _KERNEL
@@ -59,6 +60,7 @@
 typedef struct {
 	int brand;
 	const char *compat_3_brand;	/* pre Binutils 2.10 method (FBSD 3) */
+	int (*match_abi_note)(const Elf_Note *);
 	const char *emul_path;
 	const char *interp_path;
         struct sysentvec *sysvec;