ref: 75c92428225428c8fde2d015f010e608a0b12f1d
dir: /os/boot/pc/boot.c/
#include "u.h"
#include "lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "io.h"
#include "../../../utils/libmach/elf.h"
static uchar elfident[7] = {
'\177', 'E', 'L', 'F', '\1', '\1', '\1'
};
static Ehdr ehdr, rehdr;
static Phdr *phdr;
static int curphdr;
static ulong curoff;
static ulong elftotal;
static long (*swal)(long);
static ushort (*swab)(ushort);
/*
* big-endian short
*/
ushort
beswab(ushort s)
{
uchar *p;
p = (uchar*)&s;
return (p[0]<<8) | p[1];
}
/*
* big-endian long
*/
long
beswal(long l)
{
uchar *p;
p = (uchar*)&l;
return (p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];
}
/*
* little-endian short
*/
ushort
leswab(ushort s)
{
uchar *p;
p = (uchar*)&s;
return (p[1]<<8) | p[0];
}
/*
* little-endian long
*/
long
leswal(long l)
{
uchar *p;
p = (uchar*)&l;
return (p[3]<<24) | (p[2]<<16) | (p[1]<<8) | p[0];
}
/*
* Convert header to canonical form
*/
static void
hswal(long *lp, int n, long (*swap) (long))
{
while (n--) {
*lp = (*swap) (*lp);
lp++;
}
}
static int
readehdr(Boot *b)
{
int i;
/* bitswap the header according to the DATA format */
if(ehdr.ident[CLASS] != ELFCLASS32) {
print("bad ELF class - not 32 bit\n");
return 0;
}
if(ehdr.ident[DATA] == ELFDATA2LSB) {
swab = leswab;
swal = leswal;
} else if(ehdr.ident[DATA] == ELFDATA2MSB) {
swab = beswab;
swal = beswal;
} else {
print("bad ELF encoding - not big or little endian\n");
return 0;
}
memmove(&rehdr, &ehdr, sizeof(Ehdr));
ehdr.type = swab(ehdr.type);
ehdr.machine = swab(ehdr.machine);
ehdr.version = swal(ehdr.version);
ehdr.elfentry = swal(ehdr.elfentry);
ehdr.phoff = swal(ehdr.phoff);
ehdr.shoff = swal(ehdr.shoff);
ehdr.flags = swal(ehdr.flags);
ehdr.ehsize = swab(ehdr.ehsize);
ehdr.phentsize = swab(ehdr.phentsize);
ehdr.phnum = swab(ehdr.phnum);
ehdr.shentsize = swab(ehdr.shentsize);
ehdr.shnum = swab(ehdr.shnum);
ehdr.shstrndx = swab(ehdr.shstrndx);
if(ehdr.type != EXEC || ehdr.version != CURRENT)
return 0;
if(ehdr.phentsize != sizeof(Phdr))
return 0;
if(debug)
print("readehdr OK entry 0x%lux\n", ehdr.elfentry);
curoff = sizeof(Ehdr);
i = ehdr.phoff+ehdr.phentsize*ehdr.phnum - curoff;
b->state = READPHDR;
b->bp = (char*)malloc(i);
b->wp = b->bp;
b->ep = b->wp + i;
phdr = (Phdr*)(b->bp + ehdr.phoff-sizeof(Ehdr));
if(debug)
print("phdr...");
return 1;
}
static int
nextphdr(Boot *b)
{
Phdr *php;
ulong entry, offset;
char *paddr;
if(debug)
print("readedata %d\n", curphdr);
for(; curphdr < ehdr.phnum; curphdr++){
php = phdr+curphdr;
if(php->type != LOAD)
continue;
offset = php->offset;
paddr = (char*)PADDR(php->paddr);
if(offset < curoff){
/*
* Can't (be bothered to) rewind the
* input, it might be from tftp. If we
* did then we could boot FreeBSD kernels
* too maybe.
*/
return 0;
}
if(php->offset > curoff){
b->state = READEPAD;
b->bp = (char*)malloc(offset - curoff);
b->wp = b->bp;
b->ep = b->wp + offset - curoff;
if(debug)
print("nextphdr %lud...\n", offset - curoff);
return 1;
}
b->state = READEDATA;
b->bp = paddr;
b->wp = b->bp;
b->ep = b->wp+php->filesz;
print("%ud+", php->filesz);
elftotal += php->filesz;
if(debug)
print("nextphdr %ud@0x%p\n", php->filesz, paddr);
return 1;
}
if(curphdr != 0){
print("=%lud\n", elftotal);
b->state = TRYBOOT;
entry = ehdr.elfentry & ~0xF0000000;
PLLONG(b->exec.entry, entry);
return 1;
}
return 0;
}
static int
readepad(Boot *b)
{
Phdr *php;
php = phdr+curphdr;
if(debug)
print("readepad %d\n", curphdr);
curoff = php->offset;
return nextphdr(b);
}
static int
readedata(Boot *b)
{
Phdr *php;
php = phdr+curphdr;
if(debug)
print("readedata %d\n", curphdr);
if(php->filesz < php->memsz){
print("%lud", php->memsz-php->filesz);
elftotal += php->memsz-php->filesz;
memset((char*)(PADDR(php->paddr)+php->filesz), 0, php->memsz-php->filesz);
}
curoff = php->offset+php->filesz;
curphdr++;
return nextphdr(b);
}
static int
readphdr(Boot *b)
{
Phdr *php;
php = phdr;
hswal((long*)php, ehdr.phentsize*ehdr.phnum/sizeof(long), swal);
if(debug)
print("phdr curoff %lud vaddr 0x%lux paddr 0x%lux\n",
curoff, php->vaddr, php->paddr);
curoff = ehdr.phoff+ehdr.phentsize*ehdr.phnum;
curphdr = 0;
return nextphdr(b);
}
static int
addbytes(char **dbuf, char *edbuf, char **sbuf, char *esbuf)
{
int n;
n = edbuf - *dbuf;
if(n <= 0)
return 0;
if(n > esbuf - *sbuf)
n = esbuf - *sbuf;
if(n <= 0)
return -1;
memmove(*dbuf, *sbuf, n);
*sbuf += n;
*dbuf += n;
return edbuf - *dbuf;
}
int
bootpass(Boot *b, void *vbuf, int nbuf)
{
char *buf, *ebuf;
Exec *ep;
ulong entry, data, text, bss;
if(b->state == FAILED)
return FAIL;
if(nbuf == 0)
goto Endofinput;
buf = vbuf;
ebuf = buf+nbuf;
while(addbytes(&b->wp, b->ep, &buf, ebuf) == 0) {
switch(b->state) {
case INITKERNEL:
b->state = READEXEC;
b->bp = (char*)&b->exec;
b->wp = b->bp;
b->ep = b->bp+sizeof(Exec);
break;
case READEXEC:
ep = &b->exec;
if(GLLONG(ep->magic) == I_MAGIC) {
b->state = READ9TEXT;
b->bp = (char*)PADDR(GLLONG(ep->entry));
b->wp = b->bp;
b->ep = b->wp+GLLONG(ep->text);
print("%lud", GLLONG(ep->text));
break;
}
/* check for gzipped kernel */
if(b->bp[0] == 0x1F && (uchar)b->bp[1] == 0x8B && b->bp[2] == 0x08) {
b->state = READGZIP;
b->bp = (char*)malloc(1440*1024);
b->wp = b->bp;
b->ep = b->wp + 1440*1024;
memmove(b->bp, &b->exec, sizeof(Exec));
b->wp += sizeof(Exec);
print("gz...");
break;
}
/*
* Check for ELF.
*/
if(memcmp(b->bp, elfident, 4) == 0){
b->state = READEHDR;
b->bp = (char*)&ehdr;
b->wp = b->bp;
b->ep = b->wp + sizeof(Ehdr);
memmove(b->bp, &b->exec, sizeof(Exec));
b->wp += sizeof(Exec);
print("elf...");
break;
}
print("bad kernel format\n");
b->state = FAILED;
return FAIL;
case READ9TEXT:
ep = &b->exec;
b->state = READ9DATA;
b->bp = (char*)PGROUND(PADDR(GLLONG(ep->entry))+GLLONG(ep->text));
b->wp = b->bp;
b->ep = b->wp + GLLONG(ep->data);
print("+%ld", GLLONG(ep->data));
break;
case READ9DATA:
ep = &b->exec;
bss = GLLONG(ep->bss);
print("+%ld=%ld\n",
bss, GLLONG(ep->text)+GLLONG(ep->data)+bss);
b->state = TRYBOOT;
return ENOUGH;
case READEHDR:
if(!readehdr(b)){
print("readehdr failed\n");
b->state = FAILED;
return FAIL;
}
break;
case READPHDR:
if(!readphdr(b)){
b->state = FAILED;
return FAIL;
}
break;
case READEPAD:
if(!readepad(b)){
b->state = FAILED;
return FAIL;
}
break;
case READEDATA:
if(!readedata(b)){
b->state = FAILED;
return FAIL;
}
if(b->state == TRYBOOT)
return ENOUGH;
break;
case TRYBOOT:
case READGZIP:
return ENOUGH;
case READ9LOAD:
case INIT9LOAD:
panic("9load");
default:
panic("bootstate");
}
}
return MORE;
Endofinput:
/* end of input */
switch(b->state) {
case INITKERNEL:
case READEXEC:
case READ9TEXT:
case READ9DATA:
case READEHDR:
case READPHDR:
case READEPAD:
case READEDATA:
print("premature EOF\n");
b->state = FAILED;
return FAIL;
case TRYBOOT:
entry = GLLONG(b->exec.entry);
print("entry: 0x%lux\n", entry);
warp9(PADDR(entry));
b->state = FAILED;
return FAIL;
case READGZIP:
ep = &b->exec;
if(b->bp[0] != 0x1F || (uchar)b->bp[1] != 0x8B || b->bp[2] != 0x08)
print("lost magic\n");
print("%ld => ", b->wp - b->bp);
if(gunzip((uchar*)ep, sizeof(*ep), (uchar*)b->bp, b->wp - b->bp) < sizeof(*ep)) {
print("badly compressed kernel\n");
return FAIL;
}
entry = GLLONG(ep->entry);
text = GLLONG(ep->text);
data = GLLONG(ep->data);
bss = GLLONG(ep->bss);
print("%lud+%lud+%lud=%lud\n", text, data, bss, text+data+bss);
if(gunzip((uchar*)PADDR(entry)-sizeof(Exec), sizeof(Exec)+text+data,
(uchar*)b->bp, b->wp-b->bp) < sizeof(Exec)+text+data) {
print("error uncompressing kernel\n");
return FAIL;
}
/* relocate data to start at page boundary */
memmove((void*)PGROUND(PADDR(entry+text)), (void*)(PADDR(entry+text)), data);
print("entry: %lux\n", entry);
warp9(PADDR(entry));
b->state = FAILED;
return FAIL;
case INIT9LOAD:
case READ9LOAD:
panic("end 9load");
default:
panic("bootdone");
}
b->state = FAILED;
return FAIL;
}