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/*
* Transform a Plan 9 386 bootable image to make it compatible with
* the Xen binary image loader:
*
* - pad the beginning of the text with zeroes so that the image can be loaded at
* guest 'physical' address 0
* - insert a Xen header
* - pad the end of the text so that data segment is page-aligned in the file
* - adjust the linenumber-pc table so Plan 9 debuggers won't be confused
*/
#include <u.h>
#include <libc.h>
#include <bio.h>
#include <mach.h>
#define PAGE 4096
#define PLAN9HDR 32
#define XENHDR 32
#define KZERO 0x80000000
#define FLAG_VALID (1<<16)
#define FLAG_PAE (1<<14)
void
lput(long n)
{
char buf[sizeof(long)];
int i;
for (i = sizeof(long)-1; i >= 0; i--) {
buf[i] = n;
n >>= 8;
}
write(1, buf, sizeof(long));
}
void
rput(long n)
{
char buf[sizeof(long)];
int i;
for (i = 0; i < sizeof(long); i++) {
buf[i] = n;
n >>= 8;
}
write(1, buf, sizeof(long));
}
void
copy(long n)
{
char buf[PAGE];
int m;
while (n > 0) {
m = sizeof buf;
if (m > n)
m = n;
read(0, buf, m);
write(1, buf, m);
n -= m;
}
}
void pad(int n)
{
char buf[PAGE];
int m;
memset(buf, 0, sizeof buf);
while (n > 0) {
m = sizeof buf;
if (m > n)
m = n;
write(1, buf, m);
n -= m;
}
}
/*
* See /sys/src/cmd/8l/span.c:/^asmlc
*/
void adjustlnpc(int v)
{
char buf[PAGE];
int n, s;
n = 0;
while (v) {
s = 127;
if (v < 127)
s = v;
buf[n++] = s+128;
if (n == sizeof buf) {
write(1, buf, n);
n = 0;
}
v -= s;
}
if (n > 0)
write(1, buf, n);
}
void
main(int argc, char **argv)
{
Fhdr fhdr;
long newtxtsz;
long newentry;
long newlnpcsz;
long prepad, postpad;
long flags;
flags = FLAG_VALID;
if (argc > 1 && strcmp(argv[1], "-p") == 0)
flags |= FLAG_PAE;
crackhdr(0, &fhdr);
newtxtsz = ((fhdr.txtsz+PLAN9HDR+PAGE-1)&~(PAGE-1)) - PLAN9HDR;
newentry = KZERO+PLAN9HDR;
prepad = fhdr.entry - newentry;
postpad = newtxtsz - fhdr.txtsz;
newtxtsz += prepad;
newlnpcsz = fhdr.lnpcsz;
if (newlnpcsz)
newlnpcsz += (prepad+126)/127;
/* plan 9 header */
lput(4*11*11+7); /* magic */
lput(newtxtsz); /* sizes */
lput(fhdr.datsz);
lput(fhdr.bsssz);
lput(fhdr.symsz); /* nsyms */
lput(newentry); /* va of entry */
lput(fhdr.sppcsz); /* sp offsets */
lput(newlnpcsz); /* line offsets */
/* xen header */
rput(0x336EC578); /* magic */
rput(flags); /* flags */
rput(-(0x336EC578+flags)); /* checksum */
rput(newentry); /* header_addr */
rput(KZERO); /* load_addr */
rput(KZERO+newtxtsz+fhdr.datsz); /* load_end_addr */
rput(KZERO+newtxtsz+fhdr.datsz+fhdr.bsssz); /* bss_end_addr */
rput(fhdr.entry); /* entry_addr */
pad(prepad-XENHDR);
seek(0, fhdr.txtoff, 0);
copy(fhdr.txtsz);
pad(postpad);
copy(fhdr.datsz);
copy(fhdr.symsz);
if (newlnpcsz) {
adjustlnpc(prepad);
copy(fhdr.lnpcsz);
}
exits(0);
}
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