Russ, Here's the updated patch.  I made the elfdotout function more
general so that it could handle cracking ELF headers for any architecture
and added in support for POWER and MIPS (since ql and vl both generate
ELF32 for -H5).  This works with ql and vl emitted ELFs.
The section search could be stricter (ie. right now the data section can
have the X bit set), but the ql elf code spits out data with RWX.

Reference: /n/sources/patch/applied/libmach-elf2
Date: Sat Feb  5 14:30:00 CET 2005

--- /sys/src/libmach/executable.c	Sat Feb  5 14:30:00 2005
+++ /sys/src/libmach/executable.c	Sat Feb  5 14:30:00 2005
@@ -35,6 +35,7 @@
 static	void	setdata(Fhdr*, long, long, long, long);
 static	void	settext(Fhdr*, long, long, long, long);
 static	void	hswal(long*, int, long(*)(long));
+static	long	noswal(long);
 static	long	_round(long, long);
 
 /*
@@ -152,13 +153,13 @@
 		sizeof(Exec),
 		beswal,
 		common },
-	{ ELF_MAG,
-		"Irix 5.X Elf executable",
+	{ ELF_MAG,			/* any elf32 */
+		"Elf executable",
 		nil,
-		FMIPS,
-		&mmips,
+		FNONE,
+		&mi386,
 		sizeof(Ehdr),
-		beswal,
+		noswal,
 		elfdotout },
 	{ E_MAGIC,			/* Arm 5.out */
 		"Arm plan 9 executable",
@@ -268,6 +269,14 @@
 	}
 }
 /*
+ * noop
+ */
+static long
+noswal(long x)
+{
+	return x;
+}
+/*
  *	Crack a normal a.out-type header
  */
 static int
@@ -438,122 +447,108 @@
 	return 1;
 }
 
-static Shdr*
-elfsectbyname(int fd, Ehdr *hp, Shdr *sp, char *name)
-{
-	int i, offset, n;
-	char s[64];
 
-	offset = sp[hp->shstrndx].offset;
-	for(i = 1; i < hp->shnum; i++) {
-		seek(fd, offset+sp[i].name, 0);
-		n = read(fd, s, sizeof(s)-1);
-		if(n < 0)
-			continue;
-		s[n] = 0;
-		if(strcmp(s, name) == 0)
-			return &sp[i]; 
-	}
-	return 0;
-}
 /*
- *	Decode an Irix 5.x ELF header
+ * Elf32 binaries.
  */
 static int
 elfdotout(int fd, Fhdr *fp, ExecHdr *hp)
 {
 
+	long (*swal)(long);
+	ushort (*swab)(ushort);
 	Ehdr *ep;
-	Shdr *es, *txt, *init, *s;
-	long addr, size, offset, bsize;
+	Phdr *ph;
+	int i, it, id, is, phsz;
 
+	/* bitswap the header according to the DATA format */
 	ep = &hp->e;
-	if(ep->type != 8 || ep->machine != 2 || ep->version != 1)
+	if(ep->ident[CLASS] != ELFCLASS32) {
+		werrstr("bad ELF class - not 32 bit");
 		return 0;
-
-	fp->magic = ELF_MAG;
-	fp->hdrsz = (ep->ehsize+ep->phnum*ep->phentsize+16)&~15;
-
-	if(ep->shnum <= 0) {
-		werrstr("no ELF header sections");
+	}
+	if(ep->ident[DATA] == ELFDATA2LSB) {
+		swab = leswab;
+		swal = leswal;
+	} else if(ep->ident[DATA] == ELFDATA2MSB) {
+		swab = beswab;
+		swal = beswal;
+	} else {
+		werrstr("bad ELF encoding - not big or little endian");
 		return 0;
 	}
-	es = malloc(sizeof(Shdr)*ep->shnum);
-	if(es == 0)
+
+	ep->type = swab(ep->type);
+	ep->machine = swab(ep->machine);
+	ep->version = swal(ep->version);
+	ep->elfentry = swal(ep->elfentry);
+	ep->phoff = swal(ep->phoff);
+	ep->shoff = swal(ep->shoff);
+	ep->flags = swal(ep->flags);
+	ep->ehsize = swab(ep->ehsize);
+	ep->phentsize = swab(ep->phentsize);
+	ep->phnum = swab(ep->phnum);
+	ep->shentsize = swab(ep->shentsize);
+	ep->shnum = swab(ep->shnum);
+	ep->shstrndx = swab(ep->shstrndx);
+	if(ep->type != EXEC || ep->version != CURRENT)
 		return 0;
 
-	seek(fd, ep->shoff, 0);
-	if(read(fd, es, sizeof(Shdr)*ep->shnum) < 0){
-		free(es);
+	/* we could definitely support a lot more machines here */
+	fp->magic = ELF_MAG;
+	fp->hdrsz = (ep->ehsize+ep->phnum*ep->phentsize+16)&~15;
+	switch(ep->machine) {
+	case MIPS:
+		mach = &mmips;
+		fp->type = FMIPS;
+		break;
+	case POWER:
+		mach = &mpower;
+		fp->type = FPOWER;
+		break;
+	default:
 		return 0;
 	}
 
-	txt = elfsectbyname(fd, ep, es, ".text");
-	init = elfsectbyname(fd, ep, es, ".init");
-	if(txt == 0 || init == 0 || init != txt+1)
-		goto bad;
-	if(txt->addr+txt->size != init->addr)
-		goto bad;
-	settext(fp, ep->elfentry, txt->addr, txt->size+init->size, txt->offset);
-
-	addr = 0;
-	offset = 0;
-	size = 0;
-	s = elfsectbyname(fd, ep, es, ".data");
-	if(s) {
-		addr = s->addr;
-		size = s->size;
-		offset = s->offset;
-	}
-
-	s = elfsectbyname(fd, ep, es, ".rodata");
-	if(s) {
-		if(addr){
-			if(addr+size != s->addr)
-				goto bad;
-		} else {
-			addr = s->addr;
-			offset = s->offset;
-		}
-		size += s->size;
+	if(ep->phentsize != sizeof(Phdr)) {
+		werrstr("bad ELF header size");
+		return 0;
 	}
-
-	s = elfsectbyname(fd, ep, es, ".got");
-	if(s) {
-		if(addr){
-			if(addr+size != s->addr)
-				goto bad;
-		} else {
-			addr = s->addr;
-			offset = s->offset;
-		}
-		size += s->size;
+	phsz = sizeof(Phdr)*ep->phnum;
+	ph = malloc(phsz);
+	if(!ph)
+		return 0;
+	seek(fd, ep->phoff, 0);
+	if(read(fd, ph, phsz) < 0) {
+		free(ph);
+		return 0;
 	}
+	hswal((long*)ph, phsz/sizeof(long), swal);
 
-	bsize = 0;
-	s = elfsectbyname(fd, ep, es, ".bss");
-	if(s) {
-		if(addr){
-			if(addr+size != s->addr)
-				goto bad;
-		} else {
-			addr = s->addr;
-			offset = s->offset;
-		}
-		bsize = s->size;
+	/* find text, data and symbols and install them */
+	it = id = is = -1;
+	for(i = 0; i < ep->phnum; i++) {
+		if(ph[i].type == LOAD 
+		&& (ph[i].flags & (R|X)) == (R|X) && it == -1)
+			it = i;
+		else if(ph[i].type == LOAD 
+		&& (ph[i].flags & (R|W)) == (R|W) && id == -1)
+			id = i;
+		else if(ph[i].type == NOPTYPE && is == -1)
+			is = i;
+	}
+	if(it == -1 || id == -1) {
+		werrstr("No TEXT or DATA sections");
+		free(ph);
+		return 0;
 	}
 
-	if(addr == 0)
-		goto bad;
-
-	setdata(fp, addr, size, offset, bsize);
-	fp->name = "IRIX Elf a.out executable";
-	free(es);
+	settext(fp, ep->elfentry, ph[it].vaddr, ph[it].memsz, ph[it].offset);
+	setdata(fp, ph[id].vaddr, ph[id].memsz, ph[id].offset, ph[id].memsz - ph[id].filesz);
+	if(is != -1)
+		setsym(fp, ph[is].filesz, 0, ph[is].memsz, ph[is].offset);
+	free(ph);
 	return 1;
-bad:
-	free(es);
-	werrstr("ELF sections scrambled");
-	return 0;
 }
 
 /*
--- /sys/src/libmach/elf.h	Sat Feb  5 14:30:00 2005
+++ /sys/src/libmach/elf.h	Sat Feb  5 14:30:00 2005
@@ -79,6 +79,7 @@
 	I860 = 7,		/* Intel i860 */
 	MIPS = 8,		/* Mips R2000 */
 	S370 = 9,		/* Amdhal	*/
+	POWER = 20,	/* PowerPC */
 
 	NO_VERSION = 0,		/* version, ident[VERSION] */
 	CURRENT = 1,