20060303

1 files changed, 451 insertions, 0 deletions

diff --git a/os/boot/pc/boot.c b/os/boot/pc/boot.c
new file mode 100644
index 00000000..0659edbd
--- /dev/null
+++ b/os/boot/pc/boot.c
@@ -0,0 +1,451 @@
+#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;
+}