import xen 32 bit paravirtual kernel from /n/sources/xen.

1 files changed, 157 insertions, 0 deletions

diff --git a/sys/src/9/xen/xenelf.c b/sys/src/9/xen/xenelf.c
new file mode 100644
index 000000000..130d4b201
--- /dev/null
+++ b/sys/src/9/xen/xenelf.c
@@ -0,0 +1,157 @@
+#include <u.h>
+#include <libc.h>
+#include "/sys/src/libmach/elf.h"
+
+enum {
+	Page = 4096,
+};
+
+#define ROUND(n) ((n+Page-1)&~(Page-1))
+
+Shdr isect, csect;
+
+static ushort
+GETS(void *a)
+{
+	uchar *p = a;
+	return p[0] | p[1]<<8;
+}
+
+static ulong
+GETL(void *a)
+{
+	uchar *p = a;
+	return p[0] | p[1]<<8 | p[2]<<16 | p[3]<<24;
+}
+
+static void
+PUTS(void *a, ushort v)
+{
+	uchar *p = a;
+	p[0] = v;
+	p[1] = v>>8;
+}
+
+static void
+PUTL(void *a, ulong v)
+{
+	uchar *p = a;
+	p[0] = v;
+	p[1] = v>>8;
+	p[2] = v>>16;
+	p[3] = v>>24;
+}
+
+void
+copy(int fin, int fout, ulong src, ulong dst, ulong size)
+{
+	char buf[Page];
+	int n;
+
+	seek(fin, src, 0);
+	seek(fout, dst, 0);
+	n = Page;
+	while (size > 0) {
+		if (n > size)
+			n = size;
+		read(fin, buf, n);
+		write(fout, buf, n);
+		size -= n;
+	}
+}
+
+void
+main(int argc, char **argv)
+{
+	Ehdr e;
+	Shdr s;
+	Phdr p;
+	int efd, ofd, ns, i, n;
+	ulong shoff, off, noff, size, msize;
+	char *sname, *sval;
+
+	if (argc != 5)
+		sysfatal("Usage: xenelf input-elf-file output-elf-file section-name section-contents");
+	efd = open(argv[1], OREAD);
+	if (efd < 0)
+		sysfatal("%s: %r", argv[1]);
+	ofd = create(argv[2], OWRITE, 0666);
+	if (ofd < 0)
+		sysfatal("%s: %r", argv[2]);
+	sname = argv[3];
+	sval = argv[4];
+
+	read(efd, &e, sizeof e);
+	//if (e.shstrndx)
+	//	sysfatal("section header string index already present");
+	
+	/* page-align loadable segments in file */
+	ns = GETS(&e.phnum);
+	shoff = GETL(&e.phoff);
+	noff = shoff+ns*sizeof(Phdr);
+	noff = ROUND(noff);
+	for (i = 0; i < ns; i++) {
+		seek(efd, shoff+i*sizeof(Phdr), 0);
+		read(efd, &p, sizeof p);
+		off = GETL(&p.offset);
+		PUTL(&p.offset, noff);
+		size = GETL(&p.filesz);
+		copy(efd, ofd, off, noff, size);
+		if (GETL(&p.type) == LOAD) {
+			size = ROUND(size);
+			PUTL(&p.filesz, size);
+			if ((msize = GETL(&p.memsz)) != 0 && size > msize)
+				PUTL(&p.memsz, size);
+		} else {
+			/* memory size for symtab segment is actually line number table size */
+			msize = GETL(&p.memsz);
+			copy(efd, ofd, off+size, noff+size, msize);
+			noff += msize;
+		}
+		noff += size;
+		seek(ofd, shoff+i*sizeof(Phdr), 0);
+		write(ofd, &p, sizeof p);
+	}
+
+	/* append single-entry shstrndx */
+	PUTL(&isect.offset, seek(ofd, noff, 0));
+	n = strlen(sname);
+	PUTL(&isect.size, n+2);
+	write(ofd, sname+n, 1);
+	write(ofd, sname, n+1);
+	
+	/* append comment section contents */
+	PUTL(&csect.name, 1);
+	PUTL(&csect.offset, seek(ofd, 0, 2));
+	n = strlen(sval);
+	PUTL(&csect.size, n+1);
+	write(ofd, sval, n+1);
+	
+	/* copy existing section headers to end */
+	ns = 0; //GETS(&e.shnum);
+	shoff = GETL(&e.shoff);
+	PUTL(&e.shoff, seek(ofd, 0, 2));
+	for (i = 0; i < ns; i++) {
+		seek(efd, shoff+i*sizeof(Shdr), 0);
+		read(efd, &s, sizeof s);
+		seek(ofd, 0, 2);
+		write(ofd, &s, sizeof s);
+	}
+	
+	/* append section header for comment section */
+	write(ofd, &csect, sizeof csect);
+	++ns;
+
+	/* append section header for shstrndx */
+	PUTS(&e.shstrndx, ns);
+	++ns;
+	write(ofd, &isect, sizeof isect);
+
+	/* rewrite elf header */
+	PUTS(&e.shentsize, sizeof(Shdr));
+	PUTS(&e.shnum, ns);
+	seek(ofd, 0, 0);
+	write(ofd, &e, sizeof e);
+
+	exits(0);
+}