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xv6-cs450
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PDF at http://am.lcs.mit.edu/~rsc/xv6.pdf 

Various changes made while offline.

 + bwrite sector argument is redundant; use b->sector.
 + reformatting of files for nicer PDF page breaks
 + distinguish between locked, unlocked inodes in type signatures
 + change FD_FILE to FD_INODE
 + move userinit (nee proc0init) to proc.c
 + move ROOTDEV to param.h
 + always parenthesize sizeof argument
This commit is contained in:
rsc 2007-08-22 06:01:32 +00:00
parent 3dcf889c1b
commit eaea18cb9c
25 changed files with 637 additions and 669 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

46
BUGS
View File

@ -4,47 +4,11 @@ proc.c:
and be able to break out with an error return. and be able to break out with an error return.
it is better if you check *before* sleep. it is better if you check *before* sleep.
can swap procdump up after proc_kill
and then have proc_exit and proc_wait on same sheet
sched -> switch2scheduler? or just switch?
factor out switching and scheduling code from process code
shuffle for formatting
syscall.c: syscall.c:
cannot convince runoff1 to split the extern lists to fill previous page completely. cannot convince runoff1 to split the extern lists
to fill previous page completely.
fs.c: split all name operations off in name.c? (starting with namei but formatting:
wdir keep in fs.c) file.c filewrite leaks onto next page
locking? need to fix PAGEBREAK mechanism
shuffle for formatting
pipe.c:
more comments?
comment how functions get called?
sysfile.c:
is the sys_exec picture upside down?
can sys_open and sys_exec be simplified any?
general:
sizeof parens?
bio.c:
decide odd or even
bwrite doesn't need a second argument
file.c:
move fileincref onto page 1?
L=$HOME/mit/l
(for i in *.c; do xoc -x xgnu -x ./nodecleq.zeta --typesonly $i; done) 2>&1 | grep warning
saw random sharedfd failure.
why does fdalloc consume reference?
why mkdir and create?

5
bio.c
View File

@ -117,12 +117,11 @@ bread(uint dev, uint sector)
// Write buf's contents to disk. // Write buf's contents to disk.
// Must be locked. // Must be locked.
void void
bwrite(struct buf *b, uint sector) bwrite(struct buf *b)
{ {
if((b->flags & B_BUSY) == 0) if((b->flags & B_BUSY) == 0)
panic("bwrite"); panic("bwrite");
ide_rw(b->dev & 0xff, b->sector, b->data, 1, 0);
ide_rw(b->dev & 0xff, sector, b->data, 1, 0);
b->flags |= B_VALID; b->flags |= B_VALID;
} }

61
bootmain.c
View File

@ -25,6 +25,7 @@
// * cmain() in this file takes over, // * cmain() in this file takes over,
// reads in the kernel and jumps to it. // reads in the kernel and jumps to it.
//PAGEBREAK!
#include "types.h" #include "types.h"
#include "elf.h" #include "elf.h"
#include "x86.h" #include "x86.h"
@ -32,7 +33,6 @@
#define SECTSIZE 512 #define SECTSIZE 512
#define ELFHDR ((struct elfhdr*) 0x10000) // scratch space #define ELFHDR ((struct elfhdr*) 0x10000) // scratch space
void readsect(void*, uint);
void readseg(uint, uint, uint); void readseg(uint, uint, uint);
void void
@ -64,8 +64,37 @@ bad:
; ;
} }
void
waitdisk(void)
{
// wait for disk reaady
while((inb(0x1F7) & 0xC0) != 0x40)
;
}
// Read a single sector at offset into dst.
void
readsect(void *dst, uint offset)
{
// wait for disk to be ready
waitdisk();
outb(0x1F2, 1); // count = 1
outb(0x1F3, offset);
outb(0x1F4, offset >> 8);
outb(0x1F5, offset >> 16);
outb(0x1F6, (offset >> 24) | 0xE0);
outb(0x1F7, 0x20); // cmd 0x20 - read sectors
// wait for disk to be ready
waitdisk();
// read a sector
insl(0x1F0, dst, SECTSIZE/4);
}
// Read 'count' bytes at 'offset' from kernel into virtual address 'va'. // Read 'count' bytes at 'offset' from kernel into virtual address 'va'.
// Might copy more than asked // Might copy more than asked.
void void
readseg(uint va, uint count, uint offset) readseg(uint va, uint count, uint offset)
{ {
@ -90,31 +119,3 @@ readseg(uint va, uint count, uint offset)
} }
} }
void
waitdisk(void)
{
// wait for disk reaady
while((inb(0x1F7) & 0xC0) != 0x40)
;
}
void
readsect(void *dst, uint offset)
{
// wait for disk to be ready
waitdisk();
outb(0x1F2, 1); // count = 1
outb(0x1F3, offset);
outb(0x1F4, offset >> 8);
outb(0x1F5, offset >> 16);
outb(0x1F6, (offset >> 24) | 0xE0);
outb(0x1F7, 0x20); // cmd 0x20 - read sectors
// wait for disk to be ready
waitdisk();
// read a sector
insl(0x1F0, dst, SECTSIZE/4);
}

28
defs.h
View File

@ -24,6 +24,7 @@ int proc_kill(int);
int proc_wait(void); int proc_wait(void);
void yield(void); void yield(void);
void procdump(void); void procdump(void);
void userinit(void);
// setjmp.S // setjmp.S
struct jmpbuf; struct jmpbuf;
@ -117,30 +118,31 @@ void ide_rw(int, uint, void*, uint, int);
void binit(void); void binit(void);
struct buf; struct buf;
struct buf* bread(uint, uint); struct buf* bread(uint, uint);
void bwrite(struct buf*, uint); void bwrite(struct buf*);
void brelse(struct buf*); void brelse(struct buf*);
// fs.c // fs.c
struct inode; struct inode;
struct uinode;
void iinit(void); void iinit(void);
void ilock(struct inode*); struct inode* ilock(struct uinode*);
void iunlock(struct inode*); struct uinode* iunlock(struct inode*);
void idecref(struct inode*); void iput(struct uinode*);
struct inode* iincref(struct inode*); struct uinode* idup(struct uinode*);
void iput(struct inode*); struct uinode* namei(char*);
struct inode* namei(char*);
void stati(struct inode*, struct stat*); void stati(struct inode*, struct stat*);
int readi(struct inode*, char*, uint, uint); int readi(struct inode*, char*, uint, uint);
int writei(struct inode*, char*, uint, uint); int writei(struct inode*, char*, uint, uint);
struct inode* mknod(char*, short, short, short); int dirlink(struct inode *dp, char *name, uint ino);
int unlink(char*); struct uinode* dirlookup(struct inode *dp, char *name, uint *poff);
int link(char*, char*); void iupdate(struct inode *ip);
struct inode* igetroot(void); int namecmp(const char *s, const char *t);
int mkdir(char *path); struct uinode* ialloc(uint, short);
struct inode* create(char *path); struct uinode* nameiparent(char *path, char *name);
// exec.c // exec.c
int exec(char*, char**); int exec(char*, char**);
// number of elements in fixed-size array // number of elements in fixed-size array
#define NELEM(x) (sizeof(x)/sizeof((x)[0])) #define NELEM(x) (sizeof(x)/sizeof((x)[0]))

22
exec.c
View File

@ -19,7 +19,7 @@ int
exec(char *path, char **argv) exec(char *path, char **argv)
{ {
uint sz, sp, p1, p2; uint sz, sp, p1, p2;
int i, nargs, argbytes, len; int i, nargs, argbytes, len, off;
struct inode *ip; struct inode *ip;
struct elfhdr elf; struct elfhdr elf;
struct proghdr ph; struct proghdr ph;
@ -29,7 +29,7 @@ exec(char *path, char **argv)
sz = 0; sz = 0;
mem = 0; mem = 0;
if((ip = namei(path)) == 0) if((ip = ilock(namei(path))) == 0)
return -1; return -1;
if(readi(ip, (char*)&elf, 0, sizeof(elf)) < sizeof(elf)) if(readi(ip, (char*)&elf, 0, sizeof(elf)) < sizeof(elf))
@ -38,9 +38,8 @@ exec(char *path, char **argv)
if(elf.magic != ELF_MAGIC) if(elf.magic != ELF_MAGIC)
goto bad; goto bad;
for(i = 0; i < elf.phnum; i++){ for(i=0, off=elf.phoff; i<elf.phnum; i++, off+=sizeof(ph)){
if(readi(ip, (char*)&ph, elf.phoff + i * sizeof(ph), if(readi(ip, (char*)&ph, off, sizeof(ph)) != sizeof(ph))
sizeof(ph)) != sizeof(ph))
goto bad; goto bad;
if(ph.type != ELF_PROG_LOAD) if(ph.type != ELF_PROG_LOAD)
continue; continue;
@ -94,7 +93,7 @@ exec(char *path, char **argv)
for(last=s=path; *s; s++) for(last=s=path; *s; s++)
if(*s == '/') if(*s == '/')
last = s+1; last = s+1;
safestrcpy(cp->name, last, sizeof cp->name); safestrcpy(cp->name, last, sizeof(cp->name));
// commit to the new image. // commit to the new image.
kfree(cp->mem, cp->sz); kfree(cp->mem, cp->sz);
@ -102,9 +101,8 @@ exec(char *path, char **argv)
cp->mem = mem; cp->mem = mem;
mem = 0; mem = 0;
for(i = 0; i < elf.phnum; i++){ for(i=0, off=elf.phoff; i<elf.phnum; i++, off+=sizeof(ph)){
if(readi(ip, (char*)&ph, elf.phoff + i * sizeof(ph), if(readi(ip, (char*)&ph, off, sizeof(ph)) != sizeof(ph))
sizeof(ph)) != sizeof(ph))
goto bad2; goto bad2;
if(ph.type != ELF_PROG_LOAD) if(ph.type != ELF_PROG_LOAD)
continue; continue;
@ -115,7 +113,7 @@ exec(char *path, char **argv)
memset(cp->mem + ph.va + ph.filesz, 0, ph.memsz - ph.filesz); memset(cp->mem + ph.va + ph.filesz, 0, ph.memsz - ph.filesz);
} }
iput(ip); iput(iunlock(ip));
cp->tf->eip = elf.entry; cp->tf->eip = elf.entry;
cp->tf->esp = sp; cp->tf->esp = sp;
@ -126,11 +124,11 @@ exec(char *path, char **argv)
bad: bad:
if(mem) if(mem)
kfree(mem, sz); kfree(mem, sz);
iput(ip); iput(iunlock(ip));
return -1; return -1;
bad2: bad2:
iput(ip); iput(iunlock(ip));
proc_exit(); proc_exit();
return 0; return 0;
} }

38
file.c
View File

@ -11,9 +11,8 @@
#include "fs.h" #include "fs.h"
#include "fsvar.h" #include "fsvar.h"
struct spinlock file_table_lock;
struct devsw devsw[NDEV]; struct devsw devsw[NDEV];
struct spinlock file_table_lock;
struct file file[NFILE]; struct file file[NFILE];
void void
@ -22,7 +21,7 @@ fileinit(void)
initlock(&file_table_lock, "file_table"); initlock(&file_table_lock, "file_table");
} }
// Allocate a file structure // Allocate a file structure.
struct file* struct file*
filealloc(void) filealloc(void)
{ {
@ -57,16 +56,17 @@ int
fileread(struct file *f, char *addr, int n) fileread(struct file *f, char *addr, int n)
{ {
int r; int r;
struct inode *ip;
if(f->readable == 0) if(f->readable == 0)
return -1; return -1;
if(f->type == FD_PIPE) if(f->type == FD_PIPE)
return pipe_read(f->pipe, addr, n); return pipe_read(f->pipe, addr, n);
if(f->type == FD_FILE){ if(f->type == FD_INODE){
ilock(f->ip); ip = ilock(f->ip);
if((r = readi(f->ip, addr, f->off, n)) > 0) if((r = readi(ip, addr, f->off, n)) > 0)
f->off += r; f->off += r;
iunlock(f->ip); iunlock(ip);
return r; return r;
} }
panic("fileread"); panic("fileread");
@ -77,16 +77,17 @@ int
filewrite(struct file *f, char *addr, int n) filewrite(struct file *f, char *addr, int n)
{ {
int r; int r;
struct inode *ip;
if(f->writable == 0) if(f->writable == 0)
return -1; return -1;
if(f->type == FD_PIPE) if(f->type == FD_PIPE)
return pipe_write(f->pipe, addr, n); return pipe_write(f->pipe, addr, n);
if(f->type == FD_FILE){ if(f->type == FD_INODE){
ilock(f->ip); ip = ilock(f->ip);
if((r = writei(f->ip, addr, f->off, n)) > 0) if((r = writei(ip, addr, f->off, n)) > 0)
f->off += r; f->off += r;
iunlock(f->ip); iunlock(ip);
return r; return r;
} }
panic("filewrite"); panic("filewrite");
@ -96,10 +97,12 @@ filewrite(struct file *f, char *addr, int n)
int int
filestat(struct file *f, struct stat *st) filestat(struct file *f, struct stat *st)
{ {
if(f->type == FD_FILE){ struct inode *ip;
ilock(f->ip);
stati(f->ip, st); if(f->type == FD_INODE){
iunlock(f->ip); ip = ilock(f->ip);
stati(ip, st);
iunlock(ip);
return 0; return 0;
} }
return -1; return -1;
@ -110,6 +113,7 @@ void
fileclose(struct file *f) fileclose(struct file *f)
{ {
struct file ff; struct file ff;
acquire(&file_table_lock); acquire(&file_table_lock);
if(f->ref < 1 || f->type == FD_CLOSED) if(f->ref < 1 || f->type == FD_CLOSED)
@ -127,8 +131,8 @@ fileclose(struct file *f)
if(ff.type == FD_PIPE) if(ff.type == FD_PIPE)
pipe_close(ff.pipe, ff.writable); pipe_close(ff.pipe, ff.writable);
else if(ff.type == FD_FILE) else if(ff.type == FD_INODE)
idecref(ff.ip); iput(ff.ip);
else else
panic("fileclose"); panic("fileclose");
} }

4
file.h
View File

@ -1,9 +1,9 @@
struct file { struct file {
enum { FD_CLOSED, FD_NONE, FD_PIPE, FD_FILE } type; enum { FD_CLOSED, FD_NONE, FD_PIPE, FD_INODE } type;
int ref; // reference count int ref; // reference count
char readable; char readable;
char writable; char writable;
struct pipe *pipe; struct pipe *pipe;
struct inode *ip; struct uinode *ip;
uint off; uint off;
}; };

411
fs.c
View File

@ -7,8 +7,10 @@
// + Names: paths like /usr/rtm/xv6/fs.c for convenient naming. // + Names: paths like /usr/rtm/xv6/fs.c for convenient naming.
// //
// Disk layout is: superblock, inodes, disk bitmap, data blocks. // Disk layout is: superblock, inodes, disk bitmap, data blocks.
//
// TODO: Check locking! // This file contains the low-level file system manipulation
// routines. The (higher-level) system call implementations
// are in sysfile.c.
#include "types.h" #include "types.h"
#include "stat.h" #include "stat.h"
@ -25,7 +27,6 @@
#define min(a, b) ((a) < (b) ? (a) : (b)) #define min(a, b) ((a) < (b) ? (a) : (b))
static void itrunc(struct inode*); static void itrunc(struct inode*);
static void iupdate(struct inode*);
// Blocks. // Blocks.
@ -51,7 +52,7 @@ balloc(uint dev)
m = 0x1 << (bi % 8); m = 0x1 << (bi % 8);
if((bp->data[bi/8] & m) == 0) { // is block free? if((bp->data[bi/8] & m) == 0) { // is block free?
bp->data[bi/8] |= 0x1 << (bi % 8); bp->data[bi/8] |= 0x1 << (bi % 8);
bwrite(bp, BBLOCK(b, ninodes)); // mark it allocated on disk bwrite(bp); // mark it allocated on disk
brelse(bp); brelse(bp);
return b; return b;
} }
@ -74,14 +75,14 @@ bfree(int dev, uint b)
bp = bread(dev, b); bp = bread(dev, b);
memset(bp->data, 0, BSIZE); memset(bp->data, 0, BSIZE);
bwrite(bp, b); bwrite(bp);
brelse(bp); brelse(bp);
bp = bread(dev, BBLOCK(b, ninodes)); bp = bread(dev, BBLOCK(b, ninodes));
bi = b % BPB; bi = b % BPB;
m = 0x1 << (bi % 8); m = 0x1 << (bi % 8);
bp->data[bi/8] &= ~m; bp->data[bi/8] &= ~m;
bwrite(bp, BBLOCK(b, ninodes)); // mark it free on disk bwrite(bp); // mark it free on disk
brelse(bp); brelse(bp);
} }
@ -98,11 +99,20 @@ bfree(int dev, uint b)
// It is an error to use an inode without holding a reference to it. // It is an error to use an inode without holding a reference to it.
// //
// Inodes can be marked busy, just like bufs, meaning // Inodes can be marked busy, just like bufs, meaning
// that some process has logically locked the inode, and other processes // that some process has exclusive use of the inode.
// are not allowed to look at it. Because the locking can last for // Processes are only allowed to read and write inode
// a long time (for example, during a disk access), we use a flag // metadata and contents when holding the inode's lock.
// like in buffer cache, not spin locks. The inode should always be // Because inodes locks are held during disk accesses,
// locked during modifications to it. // they are implemented using a flag, as in the buffer cache,
// not using spin locks. Callers are responsible for locking
// inodes before passing them to routines in this file; leaving
// this responsibility with the caller makes it possible for them
// to create arbitrarily-sized atomic operations.
//
// To give maximum control over locking to the callers,
// the routines in this file that return inode pointers
// return pointers to *unlocked* inodes. It is the callers'
// responsibility to lock them before using them.
struct { struct {
struct spinlock lock; struct spinlock lock;
@ -116,14 +126,8 @@ iinit(void)
} }
// Find the inode with number inum on device dev // Find the inode with number inum on device dev
// and return the in-memory copy. The returned inode // and return the in-memory copy. h
// has its reference count incremented (and thus must be static struct uinode*
// idecref'ed), but is *unlocked*, meaning that none of the fields
// except dev and inum are guaranteed to be initialized.
// This convention gives the caller maximum control over blocking;
// it also guarantees that iget will not sleep, which is useful in
// the early igetroot and when holding other locked inodes.
struct inode*
iget(uint dev, uint inum) iget(uint dev, uint inum)
{ {
struct inode *ip, *empty; struct inode *ip, *empty;
@ -136,7 +140,7 @@ iget(uint dev, uint inum)
if(ip->ref > 0 && ip->dev == dev && ip->inum == inum){ if(ip->ref > 0 && ip->dev == dev && ip->inum == inum){
ip->ref++; ip->ref++;
release(&icache.lock); release(&icache.lock);
return ip; return (struct uinode*)ip;
} }
if(empty == 0 && ip->ref == 0) // Remember empty slot. if(empty == 0 && ip->ref == 0) // Remember empty slot.
empty = ip; empty = ip;
@ -153,28 +157,37 @@ iget(uint dev, uint inum)
ip->flags = 0; ip->flags = 0;
release(&icache.lock); release(&icache.lock);
return ip; return (struct uinode*)ip;
} }
// Iget the inode for the file system root (/). // Increment reference count for ip.
// This gets called before there is a current process: it cannot sleep! // Returns ip to enable ip = idup(ip1) idiom.
struct inode* struct uinode*
igetroot(void) idup(struct uinode *uip)
{ {
struct inode *ip; struct inode *ip;
ip = iget(ROOTDEV, 1);
return ip; ip = (struct inode*)uip;
acquire(&icache.lock);
ip->ref++;
release(&icache.lock);
return uip;
} }
// Lock the given inode. // Lock the given inode.
void struct inode*
ilock(struct inode *ip) ilock(struct uinode *uip)
{ {
struct buf *bp; struct buf *bp;
struct dinode *dip; struct dinode *dip;
struct inode *ip;
ip = (struct inode*)uip;
if(ip == 0)
return 0;
if(ip->ref < 1) if(ip->ref < 1)
panic("ilock"); panic("ilock: no refs");
acquire(&icache.lock); acquire(&icache.lock);
while(ip->flags & I_BUSY) while(ip->flags & I_BUSY)
@ -193,13 +206,19 @@ ilock(struct inode *ip)
memmove(ip->addrs, dip->addrs, sizeof(ip->addrs)); memmove(ip->addrs, dip->addrs, sizeof(ip->addrs));
brelse(bp); brelse(bp);
ip->flags |= I_VALID; ip->flags |= I_VALID;
if(ip->type == 0)
panic("ilock: no type");
} }
return ip;
} }
// Unlock the given inode. // Unlock the given inode.
void struct uinode*
iunlock(struct inode *ip) iunlock(struct inode *ip)
{ {
if(ip == 0)
return 0;
if(!(ip->flags & I_BUSY) || ip->ref < 1) if(!(ip->flags & I_BUSY) || ip->ref < 1)
panic("iunlock"); panic("iunlock");
@ -207,36 +226,21 @@ iunlock(struct inode *ip)
ip->flags &= ~I_BUSY; ip->flags &= ~I_BUSY;
wakeup(ip); wakeup(ip);
release(&icache.lock); release(&icache.lock);
} return (struct uinode*)ip;
// Unlock inode and drop reference.
void
iput(struct inode *ip)
{
iunlock(ip);
idecref(ip);
}
// Increment reference count for ip.
// Returns ip to enable ip = iincref(ip1) idiom.
struct inode*
iincref(struct inode *ip)
{
acquire(&icache.lock);
ip->ref++;
release(&icache.lock);
return ip;
} }
// Caller holds reference to unlocked ip. Drop reference. // Caller holds reference to unlocked ip. Drop reference.
void void
idecref(struct inode *ip) iput(struct uinode *uip)
{ {
struct inode *ip;
ip = (struct inode*)uip;
acquire(&icache.lock); acquire(&icache.lock);
if(ip->ref == 1 && (ip->flags & I_VALID) && ip->nlink == 0) { if(ip->ref == 1 && (ip->flags & I_VALID) && ip->nlink == 0) {
// inode is no longer used: truncate and free inode. // inode is no longer used: truncate and free inode.
if(ip->flags & I_BUSY) if(ip->flags & I_BUSY)
panic("idecref busy"); panic("iput busy");
ip->flags |= I_BUSY; ip->flags |= I_BUSY;
release(&icache.lock); release(&icache.lock);
// XXX convince rsc that no one will come find this inode. // XXX convince rsc that no one will come find this inode.
@ -251,7 +255,7 @@ idecref(struct inode *ip)
} }
// Allocate a new inode with the given type on device dev. // Allocate a new inode with the given type on device dev.
struct inode* struct uinode*
ialloc(uint dev, short type) ialloc(uint dev, short type)
{ {
int inum, ninodes; int inum, ninodes;
@ -270,7 +274,7 @@ ialloc(uint dev, short type)
if(dip->type == 0) { // a free inode if(dip->type == 0) { // a free inode
memset(dip, 0, sizeof(*dip)); memset(dip, 0, sizeof(*dip));
dip->type = type; dip->type = type;
bwrite(bp, IBLOCK(inum)); // mark it allocated on the disk bwrite(bp); // mark it allocated on the disk
brelse(bp); brelse(bp);
return iget(dev, inum); return iget(dev, inum);
} }
@ -280,7 +284,7 @@ ialloc(uint dev, short type)
} }
// Copy inode, which has changed, from memory to disk. // Copy inode, which has changed, from memory to disk.
static void void
iupdate(struct inode *ip) iupdate(struct inode *ip)
{ {
struct buf *bp; struct buf *bp;
@ -294,7 +298,7 @@ iupdate(struct inode *ip)
dip->nlink = ip->nlink; dip->nlink = ip->nlink;
dip->size = ip->size; dip->size = ip->size;
memmove(dip->addrs, ip->addrs, sizeof(ip->addrs)); memmove(dip->addrs, ip->addrs, sizeof(ip->addrs));
bwrite(bp, IBLOCK(ip->inum)); bwrite(bp);
brelse(bp); brelse(bp);
} }
@ -306,8 +310,8 @@ iupdate(struct inode *ip)
// listed in the block ip->addrs[INDIRECT]. // listed in the block ip->addrs[INDIRECT].
// Return the disk block address of the nth block in inode ip. // Return the disk block address of the nth block in inode ip.
// If there is no such block: if alloc is set, allocate one, else return -1. // If there is no such block, alloc controls whether one is allocated.
uint static uint
bmap(struct inode *ip, uint bn, int alloc) bmap(struct inode *ip, uint bn, int alloc)
{ {
uint addr, *a; uint addr, *a;
@ -339,7 +343,7 @@ bmap(struct inode *ip, uint bn, int alloc)
return -1; return -1;
} }
a[bn] = addr = balloc(ip->dev); a[bn] = addr = balloc(ip->dev);
bwrite(bp, ip->addrs[INDIRECT]); bwrite(bp);
} }
brelse(bp); brelse(bp);
return addr; return addr;
@ -348,6 +352,7 @@ bmap(struct inode *ip, uint bn, int alloc)
panic("bmap: out of range"); panic("bmap: out of range");
} }
// PAGEBREAK: 30
// Truncate inode (discard contents). // Truncate inode (discard contents).
static void static void
itrunc(struct inode *ip) itrunc(struct inode *ip)
@ -389,6 +394,7 @@ stati(struct inode *ip, struct stat *st)
st->size = ip->size; st->size = ip->size;
} }
//PAGEBREAK!
// Read data from inode. // Read data from inode.
int int
readi(struct inode *ip, char *dst, uint off, uint n) readi(struct inode *ip, char *dst, uint off, uint n)
@ -416,6 +422,7 @@ readi(struct inode *ip, char *dst, uint off, uint n)
return n; return n;
} }
// PAGEBREAK!
// Write data to inode. // Write data to inode.
int int
writei(struct inode *ip, char *src, uint off, uint n) writei(struct inode *ip, char *src, uint off, uint n)
@ -438,7 +445,7 @@ writei(struct inode *ip, char *src, uint off, uint n)
bp = bread(ip->dev, bmap(ip, off/BSIZE, 1)); bp = bread(ip->dev, bmap(ip, off/BSIZE, 1));
m = min(n - tot, BSIZE - off%BSIZE); m = min(n - tot, BSIZE - off%BSIZE);
memmove(bp->data + off%BSIZE, src, m); memmove(bp->data + off%BSIZE, src, m);
bwrite(bp, bmap(ip, off/BSIZE, 0)); bwrite(bp);
brelse(bp); brelse(bp);
} }
@ -449,12 +456,10 @@ writei(struct inode *ip, char *src, uint off, uint n)
return n; return n;
} }
//PAGEBREAK!
// Directories // Directories
//
// Directories are just inodes (files) filled with dirent structures.
// Compare two names, which are strings with a max length of DIRSIZ. int
static int
namecmp(const char *s, const char *t) namecmp(const char *s, const char *t)
{ {
int i; int i;
@ -468,25 +473,9 @@ namecmp(const char *s, const char *t)
return 0; return 0;
} }
// Copy one name to another.
static void
namecpy(char *s, const char *t)
{
int i;
for(i=0; i<DIRSIZ && t[i]; i++)
s[i] = t[i];
for(; i<DIRSIZ; i++)
s[i] = 0;
}
// Look for a directory entry in a directory. // Look for a directory entry in a directory.
// If not found, return -1. // If found, set *poff to byte offset of entry.
// If found: struct uinode*
// set *poff to the byte offset of the directory entry
// set *pinum to the inode number
// return 0.
static struct inode*
dirlookup(struct inode *dp, char *name, uint *poff) dirlookup(struct inode *dp, char *name, uint *poff)
{ {
uint off, inum; uint off, inum;
@ -517,18 +506,29 @@ dirlookup(struct inode *dp, char *name, uint *poff)
return 0; return 0;
} }
// Copy one name to another.
static void
namecpy(char *s, const char *t)
{
int i;
for(i=0; i<DIRSIZ && t[i]; i++)
s[i] = t[i];
for(; i<DIRSIZ; i++)
s[i] = 0;
}
// Write a new directory entry (name, ino) into the directory dp. // Write a new directory entry (name, ino) into the directory dp.
// Caller must have locked dp. int
static int
dirlink(struct inode *dp, char *name, uint ino) dirlink(struct inode *dp, char *name, uint ino)
{ {
int off; int off;
struct dirent de; struct dirent de;
struct inode *ip; struct uinode *ip;
// Double-check that name is not present. // Check that name is not present.
if((ip = dirlookup(dp, name, 0)) != 0){ if((ip = dirlookup(dp, name, 0)) != 0){
idecref(ip); iput(ip);
return -1; return -1;
} }
@ -548,49 +548,18 @@ dirlink(struct inode *dp, char *name, uint ino)
return 0; return 0;
} }
// Create a new inode named name inside dp
// and return its locked inode structure.
// If name already exists, return 0.
static struct inode*
dircreat(struct inode *dp, char *name, short type, short major, short minor)
{
struct inode *ip;
ip = ialloc(dp->dev, type);
if(ip == 0)
return 0;
ilock(ip);
ip->major = major;
ip->minor = minor;
ip->size = 0;
ip->nlink = 1;
iupdate(ip);
if(dirlink(dp, name, ip->inum) < 0){
ip->nlink = 0;
iupdate(ip);
iput(ip);
return 0;
}
return ip;
}
// Paths // Paths
// Skip over the next path element in path, // Copy the next path element from path into name.
// saving it in *name and its length in *len. // Return a pointer to the element following the copied one.
// Return a pointer to the element after that // The returned path has no leading slashes,
// (after any trailing slashes). // so the caller can check *path=='\0' to see if the name is the last one.
// Thus the caller can check whether *path=='\0' // If no name to remove, return 0.
// to see whether the name just removed was
// the last one.
// If there is no name to remove, return 0.
// //
// Examples: // Examples:
// skipelem("a/bb/c") = "bb/c", with *name = "a/bb/c", len=1 // skipelem("a/bb/c", name) = "bb/c", setting name = "a"
// skipelem("///a/bb") = "b", with *name="a/bb", len=1 // skipelem("///a/bb", name) = "b", setting name="a"
// skipelem("") = skipelem("////") = 0 // skipelem("", name) = skipelem("////", name) = 0
// //
static char* static char*
skipelem(char *path, char *name) skipelem(char *path, char *name)
@ -617,201 +586,61 @@ skipelem(char *path, char *name)
return path; return path;
} }
// look up a path name, in one of three modes. // Look up and return the inode for a path name.
// NAMEI_LOOKUP: return locked target inode. // If parent is set, return the inode for the parent
// NAMEI_CREATE: return locked parent inode. // and write the final path element to name, which
// return 0 if name does exist. // should have room for DIRSIZ bytes.
// *ret_last points to last path component (i.e. new file name). static struct uinode*
// *ret_ip points to the the name that did exist, if it did.
// *ret_ip and *ret_last may be zero even if return value is zero.
// NAMEI_DELETE: return locked parent inode, offset of dirent in *ret_off.
// return 0 if name doesn't exist.
struct inode*
_namei(char *path, int parent, char *name) _namei(char *path, int parent, char *name)
{ {
struct inode *dp, *ip; struct uinode *dp, *ip;
struct inode *dpl;
uint off; uint off;
if(*path == '/') if(*path == '/')
dp = igetroot(); dp = iget(ROOTDEV, 1);
else else
dp = iincref(cp->cwd); dp = idup(cp->cwd);
ilock(dp);
while((path = skipelem(path, name)) != 0){ while((path = skipelem(path, name)) != 0){
if(dp->type != T_DIR) dpl = ilock(dp);
goto fail; if(dpl->type != T_DIR){
iunlock(dpl);
iput(dp);
return 0;
}
if(parent && *path == '\0'){ if(parent && *path == '\0'){
// Stop one level early. // Stop one level early.
iunlock(dpl);
return dp; return dp;
} }
if((ip = dirlookup(dp, name, &off)) == 0) if((ip = dirlookup(dpl, name, &off)) == 0){
goto fail; iunlock(dpl);
iput(dp);
iput(ip);
return 0;
}
iunlock(dpl);
iput(dp); iput(dp);
ilock(ip);
dp = ip; dp = ip;
if(dp->type == 0 || dp->nlink < 1)
panic("namei");
} }
if(parent) if(parent)
return 0; return 0;
return dp; return dp;
fail:
iput(dp);
return 0;
} }
struct inode* struct uinode*
namei(char *path) namei(char *path)
{ {
char name[DIRSIZ]; char name[DIRSIZ];
return _namei(path, 0, name); return _namei(path, 0, name);
} }
static struct inode* struct uinode*
nameiparent(char *path, char *name) nameiparent(char *path, char *name)
{ {
return _namei(path, 1, name); return _namei(path, 1, name);
} }
// Create the path and return its locked inode structure.
// If cp already exists, return 0.
struct inode*
mknod(char *path, short type, short major, short minor)
{
struct inode *ip, *dp;
char name[DIRSIZ];
if((dp = nameiparent(path, name)) == 0)
return 0;
ip = dircreat(dp, name, type, major, minor);
iput(dp);
return ip;
}
// Unlink the inode named cp.
int
unlink(char *path)
{
struct inode *ip, *dp;
struct dirent de;
uint off;
char name[DIRSIZ];
if((dp = nameiparent(path, name)) == 0)
return -1;
// Cannot unlink "." or "..".
if(namecmp(name, ".") == 0 || namecmp(name, "..") == 0){
iput(dp);
return -1;
}
if((ip = dirlookup(dp, name, &off)) == 0){
iput(dp);
return -1;
}
memset(&de, 0, sizeof(de));
if(writei(dp, (char*)&de, off, sizeof(de)) != sizeof(de))
panic("unlink dir write");
iput(dp);
ilock(ip);
if(ip->nlink < 1)
panic("unlink nlink < 1");
ip->nlink--;
iupdate(ip);
iput(ip);
return 0;
}
// Create the path new as a link to the same inode as old.
int
link(char *old, char *new)
{
struct inode *ip, *dp;
char name[DIRSIZ];
if((ip = namei(old)) == 0)
return -1;
if(ip->type == T_DIR){
iput(ip);
return -1;
}
iunlock(ip);
if((dp = nameiparent(new, name)) == 0){
idecref(ip);
return -1;
}
if(dp->dev != ip->dev || dirlink(dp, name, ip->inum) < 0){
idecref(ip);
iput(dp);
return -1;
}
iput(dp);
// XXX write ordering wrong here too.
ilock(ip);
ip->nlink++;
iupdate(ip);
iput(ip);
return 0;
}
int
mkdir(char *path)
{
struct inode *dp, *ip;
char name[DIRSIZ];
// XXX write ordering is screwy here- do we care?
if((dp = nameiparent(path, name)) == 0)
return -1;
if((ip = dircreat(dp, name, T_DIR, 0, 0)) == 0){
iput(dp);
return -1;
}
dp->nlink++;
iupdate(dp);
if(dirlink(ip, ".", ip->inum) < 0 || dirlink(ip, "..", dp->inum) < 0)
panic("mkdir");
iput(dp);
iput(ip);
return 0;
}
struct inode*
create(char *path)
{
struct inode *dp, *ip;
char name[DIRSIZ];
if((dp = nameiparent(path, name)) == 0)
return 0;
if((ip = dirlookup(dp, name, 0)) != 0){
iput(dp);
ilock(ip);
if(ip->type == T_DIR){
iput(ip);
return 0;
}
return ip;
}
if((ip = dircreat(dp, name, T_FILE, 0, 0)) == 0){
iput(dp);
return 0;
}
iput(dp);
return ip;
}

6
fsvar.h
View File

@ -14,7 +14,11 @@ struct inode {
uint addrs[NADDRS]; uint addrs[NADDRS];
}; };
#define ROOTDEV 1 // Device number of root file system // unlocked inode - only dev and inum are available
struct uinode {
uint dev;
uint inum;
};
#define I_BUSY 0x1 #define I_BUSY 0x1
#define I_VALID 0x2 #define I_VALID 0x2

82
main.c
View File

@ -12,8 +12,6 @@
extern char edata[], end[]; extern char edata[], end[];
void proc0init();
// Bootstrap processor starts running C code here. // Bootstrap processor starts running C code here.
// This is called main0 not main so that it can have // This is called main0 not main so that it can have
// a void return type. Gcc can't handle functions named // a void return type. Gcc can't handle functions named
@ -35,49 +33,37 @@ main0(void)
bcpu = mp_bcpu(); bcpu = mp_bcpu();
// switch to bootstrap processor's stack // switch to bootstrap processor's stack
asm volatile("movl %0, %%esp" : : "r" (cpus[bcpu].mpstack + MPSTACK - 32)); asm volatile("movl %0, %%esp" : : "r" (cpus[bcpu].mpstack+MPSTACK-32));
asm volatile("movl %0, %%ebp" : : "r" (cpus[bcpu].mpstack + MPSTACK)); asm volatile("movl %0, %%ebp" : : "r" (cpus[bcpu].mpstack+MPSTACK));
lapic_init(bcpu); lapic_init(bcpu);
cprintf("\ncpu%d: starting xv6\n\n", cpu()); cprintf("\ncpu%d: starting xv6\n\n", cpu());
pinit(); // process table pinit(); // process table
binit(); // buffer cache binit(); // buffer cache
pic_init(); pic_init(); // interrupt controller
ioapic_init(); ioapic_init(); // another interrupt controller
kinit(); // physical memory allocator kinit(); // physical memory allocator
tvinit(); // trap vectors tvinit(); // trap vectors
idtinit(); // this CPU's interrupt descriptor table idtinit(); // interrupt descriptor table
fileinit(); fileinit(); // file table
iinit(); // i-node table iinit(); // inode cache
setupsegs(0); // segments & TSS
// make sure there's a TSS console_init(); // I/O devices & their interrupts
setupsegs(0); ide_init(); // disk
mp_startthem(); // other CPUs
// initialize I/O devices, let them enable interrupts if(ismp){
console_init(); lapic_timerinit(); // smp timer
ide_init(); lapic_enableintr(); // local interrupts
}else
// start other CPUs pit8253_timerinit(); // uniprocessor timer
mp_startthem(); userinit(); // first user process
// turn on timer
if(ismp)
lapic_timerinit();
else
pit8253_timerinit();
// enable interrupts on the local APIC
lapic_enableintr();
// enable interrupts on this processor. // enable interrupts on this processor.
cpus[cpu()].nlock--; cpus[cpu()].nlock--;
sti(); sti();
// initialize process 0
proc0init();
scheduler(); scheduler();
} }
@ -106,29 +92,3 @@ mpmain(void)
scheduler(); scheduler();
} }
void
proc0init(void)
{
struct proc *p;
extern uchar _binary_initcode_start[], _binary_initcode_size[];
p = copyproc(0);
p->sz = PAGE;
p->mem = kalloc(p->sz);
p->cwd = igetroot();
memset(&p->tf, 0, sizeof p->tf);
p->tf->es = p->tf->ds = p->tf->ss = (SEG_UDATA << 3) | DPL_USER;
p->tf->cs = (SEG_UCODE << 3) | DPL_USER;
p->tf->eflags = FL_IF;
p->tf->esp = p->sz;
// Push dummy return address to placate gcc.
p->tf->esp -= 4;
*(uint*)(p->mem + p->tf->esp) = 0xefefefef;
p->tf->eip = 0;
memmove(p->mem, _binary_initcode_start, (int)_binary_initcode_size);
safestrcpy(p->name, "initcode", sizeof p->name);
p->state = RUNNABLE;
}

1
param.h
View File

@ -8,3 +8,4 @@
#define NBUF 10 // size of disk block cache #define NBUF 10 // size of disk block cache
#define NINODE 100 // maximum number of active i-nodes #define NINODE 100 // maximum number of active i-nodes
#define NDEV 10 // maximum major device number #define NDEV 10 // maximum major device number
#define ROOTDEV 1 // device number of file system root disk

141
proc.c
View File

@ -11,7 +11,7 @@ struct spinlock proc_table_lock;
struct proc proc[NPROC]; struct proc proc[NPROC];
struct proc *curproc[NCPU]; struct proc *curproc[NCPU];
int next_pid = 1; int nextpid = 1;
extern void forkret(void); extern void forkret(void);
extern void forkret1(struct trapframe*); extern void forkret1(struct trapframe*);
@ -21,37 +21,27 @@ pinit(void)
initlock(&proc_table_lock, "proc_table"); initlock(&proc_table_lock, "proc_table");
} }
// Set up CPU's segment descriptors and task state for a // Look in the process table for an UNUSED proc.
// given process. // If found, change state to EMBRYO and return it.
// If p==0, set up for "idle" state for when scheduler() // Otherwise return 0.
// is idling, not running any process. static struct proc*
void allocproc(void)
setupsegs(struct proc *p)
{ {
struct cpu *c = &cpus[cpu()]; int i;
struct proc *p;
c->ts.ss0 = SEG_KDATA << 3; acquire(&proc_table_lock);
if(p){ for(i = 0; i < NPROC; i++){
c->ts.esp0 = (uint)(p->kstack + KSTACKSIZE); p = &proc[i];
} else { if(p->state == UNUSED){
c->ts.esp0 = 0xffffffff; p->state = EMBRYO;
p->pid = nextpid++;
release(&proc_table_lock);
return p;
}
} }
release(&proc_table_lock);
c->gdt[0] = SEG_NULL; return 0;
c->gdt[SEG_KCODE] = SEG(STA_X|STA_R, 0, 0x100000 + 64*1024-1, 0);
c->gdt[SEG_KDATA] = SEG(STA_W, 0, 0xffffffff, 0);
c->gdt[SEG_TSS] = SEG16(STS_T32A, (uint)&c->ts, sizeof(c->ts)-1, 0);
c->gdt[SEG_TSS].s = 0;
if(p){
c->gdt[SEG_UCODE] = SEG(STA_X|STA_R, (uint)p->mem, p->sz-1, DPL_USER);
c->gdt[SEG_UDATA] = SEG(STA_W, (uint)p->mem, p->sz-1, DPL_USER);
} else {
c->gdt[SEG_UCODE] = SEG_NULL;
c->gdt[SEG_UDATA] = SEG_NULL;
}
lgdt(c->gdt, sizeof c->gdt);
ltr(SEG_TSS << 3);
} }
// Grow current process's memory by n bytes. // Grow current process's memory by n bytes.
@ -73,29 +63,41 @@ growproc(int n)
return cp->sz - n; return cp->sz - n;
} }
// Look in the process table for an UNUSED proc. // Set up CPU's segment descriptors and task state for a
// If found, change state to EMBRYO and return it. // given process.
// Otherwise return 0. // If p==0, set up for "idle" state for when scheduler()
struct proc* // is idling, not running any process.
allocproc(void) void
setupsegs(struct proc *p)
{ {
int i; struct cpu *c = &cpus[cpu()];
struct proc *p;
for(i = 0; i < NPROC; i++){ c->ts.ss0 = SEG_KDATA << 3;
p = &proc[i]; if(p)
if(p->state == UNUSED){ c->ts.esp0 = (uint)(p->kstack + KSTACKSIZE);
p->state = EMBRYO; else
return p; c->ts.esp0 = 0xffffffff;
}
c->gdt[0] = SEG_NULL;
c->gdt[SEG_KCODE] = SEG(STA_X|STA_R, 0, 0x100000 + 64*1024-1, 0);
c->gdt[SEG_KDATA] = SEG(STA_W, 0, 0xffffffff, 0);
c->gdt[SEG_TSS] = SEG16(STS_T32A, (uint)&c->ts, sizeof(c->ts)-1, 0);
c->gdt[SEG_TSS].s = 0;
if(p){
c->gdt[SEG_UCODE] = SEG(STA_X|STA_R, (uint)p->mem, p->sz-1, DPL_USER);
c->gdt[SEG_UDATA] = SEG(STA_W, (uint)p->mem, p->sz-1, DPL_USER);
} else {
c->gdt[SEG_UCODE] = SEG_NULL;
c->gdt[SEG_UDATA] = SEG_NULL;
} }
return 0;
lgdt(c->gdt, sizeof(c->gdt));
ltr(SEG_TSS << 3);
} }
// Create a new process copying p as the parent. // Create a new process copying p as the parent.
// Does not copy the kernel stack. // Sets up stack to return as if from system call.
// Instead, sets up stack to return as if from system call. // Caller must set state of returned proc to RUNNABLE.
// Caller must arrange for process to run (set state to RUNNABLE).
struct proc* struct proc*
copyproc(struct proc *p) copyproc(struct proc *p)
{ {
@ -103,13 +105,8 @@ copyproc(struct proc *p)
struct proc *np; struct proc *np;
// Allocate process. // Allocate process.
acquire(&proc_table_lock); if((np = allocproc()) == 0)
if((np = allocproc()) == 0){
release(&proc_table_lock);
return 0; return 0;
}
np->pid = next_pid++;
release(&proc_table_lock);
// Allocate kernel stack. // Allocate kernel stack.
if((np->kstack = kalloc(KSTACKSIZE)) == 0){ if((np->kstack = kalloc(KSTACKSIZE)) == 0){
@ -120,7 +117,7 @@ copyproc(struct proc *p)
if(p){ // Copy process state from p. if(p){ // Copy process state from p.
np->ppid = p->pid; np->ppid = p->pid;
memmove(np->tf, p->tf, sizeof *np->tf); memmove(np->tf, p->tf, sizeof(*np->tf));
np->sz = p->sz; np->sz = p->sz;
if((np->mem = kalloc(np->sz)) == 0){ if((np->mem = kalloc(np->sz)) == 0){
@ -132,24 +129,49 @@ copyproc(struct proc *p)
memmove(np->mem, p->mem, np->sz); memmove(np->mem, p->mem, np->sz);
for(i = 0; i < NOFILE; i++){ for(i = 0; i < NOFILE; i++){
np->ofile[i] = p->ofile[i]; if((np->ofile[i] = p->ofile[i]) != 0)
if(np->ofile[i])
fileincref(np->ofile[i]); fileincref(np->ofile[i]);
} }
np->cwd = iincref(p->cwd); np->cwd = idup(p->cwd);
} }
// Set up new jmpbuf to start executing at forkret (see below). // Set up new jmpbuf to start executing at forkret (see below).
memset(&np->jmpbuf, 0, sizeof np->jmpbuf); memset(&np->jmpbuf, 0, sizeof(np->jmpbuf));
np->jmpbuf.eip = (uint)forkret; np->jmpbuf.eip = (uint)forkret;
np->jmpbuf.esp = (uint)np->tf - 4; np->jmpbuf.esp = (uint)np->tf - 4;
// Clear %eax so that fork system call returns 0 in child. // Clear %eax so that fork system call returns 0 in child.
np->tf->eax = 0; np->tf->eax = 0;
return np; return np;
} }
// Set up first user process.
void
userinit(void)
{
struct proc *p;
extern uchar _binary_initcode_start[], _binary_initcode_size[];
p = copyproc(0);
p->sz = PAGE;
p->mem = kalloc(p->sz);
p->cwd = namei("/");
memset(&p->tf, 0, sizeof(p->tf));
p->tf->es = p->tf->ds = p->tf->ss = (SEG_UDATA << 3) | DPL_USER;
p->tf->cs = (SEG_UCODE << 3) | DPL_USER;
p->tf->eflags = FL_IF;
p->tf->esp = p->sz;
// Push dummy return address to placate gcc.
p->tf->esp -= 4;
*(uint*)(p->mem + p->tf->esp) = 0xefefefef;
p->tf->eip = 0;
memmove(p->mem, _binary_initcode_start, (int)_binary_initcode_size);
safestrcpy(p->name, "initcode", sizeof(p->name));
p->state = RUNNABLE;
}
//PAGEBREAK: 42 //PAGEBREAK: 42
// Per-CPU process scheduler. // Per-CPU process scheduler.
// Each CPU calls scheduler() after setting itself up. // Each CPU calls scheduler() after setting itself up.
@ -269,6 +291,7 @@ sleep(void *chan, struct spinlock *lk)
} }
} }
//PAGEBREAK!
// Wake up all processes sleeping on chan. // Wake up all processes sleeping on chan.
// Proc_table_lock must be held. // Proc_table_lock must be held.
void void
@ -334,7 +357,7 @@ proc_exit(void)
} }
} }
idecref(cp->cwd); iput(cp->cwd);
cp->cwd = 0; cp->cwd = 0;
acquire(&proc_table_lock); acquire(&proc_table_lock);

4
proc.h
View File

@ -37,7 +37,7 @@ struct proc {
void *chan; // If non-zero, sleeping on chan void *chan; // If non-zero, sleeping on chan
int killed; // If non-zero, have been killed int killed; // If non-zero, have been killed
struct file *ofile[NOFILE]; // Open files struct file *ofile[NOFILE]; // Open files
struct inode *cwd; // Current directory struct uinode *cwd; // Current directory
struct jmpbuf jmpbuf; // Jump here to run process struct jmpbuf jmpbuf; // Jump here to run process
struct trapframe *tf; // Trap frame for current interrupt struct trapframe *tf; // Trap frame for current interrupt
char name[16]; // Process name (debugging) char name[16]; // Process name (debugging)
@ -49,8 +49,6 @@ struct proc {
// fixed-size stack // fixed-size stack
// expandable heap // expandable heap
extern struct proc proc[];
// If xv6 was only for uniprocessors, this could be // If xv6 was only for uniprocessors, this could be
// struct proc *cp; // struct proc *cp;
// Instead we have an array curproc, one per // Instead we have an array curproc, one per

12
runoff.list
View File

@ -13,7 +13,7 @@ bootasm.S
bootother.S bootother.S
bootmain.c bootmain.c
main.c main.c
mp.c initcode.S
init.c init.c
# locks # locks
@ -27,11 +27,11 @@ setjmp.S
kalloc.c kalloc.c
# system calls # system calls
syscall.h
trapasm.S
traps.h traps.h
trap.c
vectors.pl vectors.pl
trapasm.S
trap.c
syscall.h
syscall.c syscall.c
sysproc.c sysproc.c
@ -46,6 +46,7 @@ fsvar.h
ide.c ide.c
bio.c bio.c
fs.c fs.c
exec.c
file.c file.c
sysfile.c sysfile.c
@ -56,10 +57,11 @@ pipe.c
string.c string.c
# low-level PC # low-level PC
mp.c
ioapic.h ioapic.h
lapic.c lapic.c
ioapic.c ioapic.c
picirq.c picirq.c
kbd.h kbd.h
console.c console.c
8253pit.c 8253pit.c

59
runoff.spec
View File

@ -1,11 +1,50 @@
even: mmu.h # types.h either
even: bootasm.S # param.h either
even: bootother.S # defs.h either
even: bootmain.c # x86.h either
# asm.h either
# mmu.h either
# elf.h either
# mp.h either
even: bootasm.S # mild preference
even: bootother.S # mild preference
# bootmain.c either
even: main.c even: main.c
even: spinlock.c # mp.c don't care at all
even: proc.h even: initcode.S
even: proc.c odd: init.c
odd: kalloc.c
even: trap.c # spinlock.h either
odd: bio.c # spinlock.c either
even: proc.h # mild preference
even: proc.c # VERY important
# setjmp.S either
# kalloc.c either
# syscall.h either
# trapasm.S either
# traps.h either
even: trap.c # important
# vectors.pl either
# syscall.c either
# sysproc.c either
# buf.h either
# dev.h either
# fcntl.h either
# stat.h either
# file.h either
# fs.h either
# fsvar.h either
# even: ide.c
# odd: bio.c
odd: fs.c # VERY important
# file.c either
# exec.c either
# sysfile.c either
even: pipe.c # mild preference
# string.c either
# even: console.c

6
runoff1
View File

@ -45,6 +45,12 @@ for($i=0; $i<@lines; ){
$sawbrace = 0; $sawbrace = 0;
$breaksize = 15; # 15 lines to get to function $breaksize = 15; # 15 lines to get to function
for($j=$i; $j<$i+50 && $j < @lines; $j++){ for($j=$i; $j<$i+50 && $j < @lines; $j++){
if($lines[$j] =~ /PAGEBREAK!/){
$lines[$j] = "";
$breakbefore = $j;
$breaksize = 100;
last;
}
if($lines[$j] =~ /PAGEBREAK:\s*([0-9]+)/){ if($lines[$j] =~ /PAGEBREAK:\s*([0-9]+)/){
$breaksize = $1; $breaksize = $1;
$breakbefore = $j; $breakbefore = $j;

2
sh.c
View File

@ -41,7 +41,7 @@ int _gettoken(char *s, char **p1, char **p2);
int int
main(void) main(void)
{ {
while(getcmd(buf, sizeof buf) >= 0) { while(getcmd(buf, sizeof(buf)) >= 0) {
if(parse(buf) >= 0) if(parse(buf) >= 0)
runcmd(); runcmd();
} }

2
show1
View File

@ -1,3 +1,3 @@
#!/bin/sh #!/bin/sh
runoff1 "$@" | pr.pl -h "xv6/$@" | mpage -m50t50b -o -bLetter -T -t -2 -FCourier -L60 >x.ps; gv --swap x.ps runoff1 "$@" | pr.pl -h "xv6/$@" | mpage -m50t50b -o -bLetter -T -t -2 -FLucidaSans-Typewriter83 -L60 >x.ps; gv --swap x.ps

15
spinlock.c
View File

@ -36,6 +36,13 @@ getcallerpcs(void *v, uint pcs[])
pcs[i] = 0; pcs[i] = 0;
} }
// Check whether this cpu is holding the lock.
int
holding(struct spinlock *lock)
{
return lock->locked && lock->cpu == cpu() + 10;
}
// Acquire the lock. // Acquire the lock.
// Loops (spins) until the lock is acquired. // Loops (spins) until the lock is acquired.
// (Because contention is handled by spinning, // (Because contention is handled by spinning,
@ -83,11 +90,3 @@ release(struct spinlock *lock)
if(--cpus[cpu()].nlock == 0) if(--cpus[cpu()].nlock == 0)
sti(); sti();
} }
// Check whether this cpu is holding the lock.
int
holding(struct spinlock *lock)
{
return lock->locked && lock->cpu == cpu() + 10;
}

316
sysfile.c
View File

@ -11,7 +11,6 @@
#include "buf.h" #include "buf.h"
#include "fs.h" #include "fs.h"
#include "fsvar.h" #include "fsvar.h"
#include "elf.h"
#include "file.h" #include "file.h"
#include "fcntl.h" #include "fcntl.h"
@ -51,27 +50,15 @@ fdalloc(struct file *f)
} }
int int
sys_pipe(void) sys_read(void)
{ {
int *fd; struct file *f;
struct file *rf, *wf; int n;
int fd0, fd1; char *cp;
if(argptr(0, (void*)&fd, 2*sizeof fd[0]) < 0) if(argfd(0, 0, &f) < 0 || argint(2, &n) < 0 || argptr(1, &cp, n) < 0)
return -1; return -1;
if(pipe_alloc(&rf, &wf) < 0) return fileread(f, cp, n);
return -1;
fd0 = -1;
if((fd0 = fdalloc(rf)) < 0 || (fd1 = fdalloc(wf)) < 0){
if(fd0 >= 0)
cp->ofile[fd0] = 0;
fileclose(rf);
fileclose(wf);
return -1;
}
fd[0] = fd0;
fd[1] = fd1;
return 0;
} }
int int
@ -87,15 +74,14 @@ sys_write(void)
} }
int int
sys_read(void) sys_fstat(void)
{ {
struct file *f; struct file *f;
int n; struct stat *st;
char *cp;
if(argfd(0, 0, &f) < 0 || argptr(1, (void*)&st, sizeof(*st)) < 0)
if(argfd(0, 0, &f) < 0 || argint(2, &n) < 0 || argptr(1, &cp, n) < 0)
return -1; return -1;
return fileread(f, cp, n); return filestat(f, st);
} }
int int
@ -111,6 +97,150 @@ sys_close(void)
return 0; return 0;
} }
// Create the path new as a link to the same inode as old.
int
sys_link(void)
{
char name[DIRSIZ], *new, *old;
struct inode *dp, *ip;
struct uinode *ipu;
if(argstr(0, &old) < 0 || argstr(1, &new) < 0)
return -1;
if((ip = ilock(namei(old))) == 0)
return -1;
if(ip->type == T_DIR){
iput(iunlock(ip));
return -1;
}
ip->nlink++;
iupdate(ip);
ipu = iunlock(ip); ip = 0;
if((dp = ilock(nameiparent(new, name))) == 0 ||
dp->dev != ipu->dev || dirlink(dp, name, ipu->inum) < 0){
if(dp)
iput(iunlock(dp));
ip = ilock(ipu);
ip->nlink--;
iupdate(ip);
iput(iunlock(ip));
return -1;
}
iput(iunlock(dp));
iput(ipu);
return 0;
}
// Is the directory dp empty except for "." and ".." ?
static int
isdirempty(struct inode *dp)
{
int off;
struct dirent de;
for(off=2*sizeof(de); off<dp->size; off+=sizeof(de)){
if(readi(dp, (char*)&de, off, sizeof(de)) != sizeof(de))
panic("isdirempty: readi");
if(de.inum != 0)
return 0;
}
return 1;
}
int
sys_unlink(void)
{
struct inode *ip, *dp;
struct dirent de;
char name[DIRSIZ], *path;
uint off;
if(argstr(0, &path) < 0)
return -1;
if((dp = ilock(nameiparent(path, name))) == 0)
return -1;
// Cannot unlink "." or "..".
if(namecmp(name, ".") == 0 || namecmp(name, "..") == 0){
iput(iunlock(dp));
return -1;
}
if((ip = ilock(dirlookup(dp, name, &off))) == 0){
iput(iunlock(dp));
return -1;
}
if(ip->nlink < 1)
panic("unlink: nlink < 1");
if(ip->type == T_DIR && !isdirempty(ip)){
iput(iunlock(ip));
iput(iunlock(dp));
return -1;
}
memset(&de, 0, sizeof(de));
if(writei(dp, (char*)&de, off, sizeof(de)) != sizeof(de))
panic("unlink: writei");
iput(iunlock(dp));
ip->nlink--;
iupdate(ip);
iput(iunlock(ip));
return 0;
}
// Create the path and return its unlocked inode structure.
static struct inode*
mkpath(char *path, int canexist, short type, short major, short minor)
{
uint off;
struct inode *ip, *dp;
struct uinode *ipu;
char name[DIRSIZ];
if((dp = ilock(nameiparent(path, name))) == 0)
return 0;
if(canexist && (ipu = dirlookup(dp, name, &off)) != 0){
iput(iunlock(dp));
ip = ilock(ipu);
if(ip->type != type || ip->major != major || ip->minor != minor){
iput(iunlock(ip));
return 0;
}
return ip;
}
if((ip = ilock(ialloc(dp->dev, type))) == 0){
iput(iunlock(dp));
return 0;
}
ip->major = major;
ip->minor = minor;
ip->size = 0;
ip->nlink = 1;
iupdate(ip);
if(dirlink(dp, name, ip->inum) < 0){
ip->nlink = 0;
iput(iunlock(ip));
iput(iunlock(dp));
return 0;
}
if(type == T_DIR){ // Create . and .. entries.
dp->nlink++; // for ".."
iupdate(dp);
// No ip->nlink++ for ".": avoid cyclic ref count.
if(dirlink(ip, ".", ip->inum) < 0 || dirlink(ip, "..", dp->inum) < 0)
panic("mkpath dots");
}
iput(iunlock(dp));
return ip;
}
int int
sys_open(void) sys_open(void)
{ {
@ -122,30 +252,28 @@ sys_open(void)
if(argstr(0, &path) < 0 || argint(1, &omode) < 0) if(argstr(0, &path) < 0 || argint(1, &omode) < 0)
return -1; return -1;
if(omode & O_CREATE) if(omode & O_CREATE){
ip = create(path); if((ip = mkpath(path, 1, T_FILE, 0, 0)) == 0)
else return -1;
ip = namei(path); }else{
if(ip == 0) if((ip = ilock(namei(path))) == 0)
return -1; return -1;
if(ip->type == T_DIR && (omode & (O_RDWR|O_WRONLY))){
iput(iunlock(ip));
return -1;
}
}
if(ip->type == T_DIR && (omode & (O_RDWR|O_WRONLY))){ if((f = filealloc()) == 0 || (fd = fdalloc(f)) < 0){
iput(ip); if(f)
fileclose(f);
iput(iunlock(ip));
return -1; return -1;
} }
if((f = filealloc()) == 0){ f->type = FD_INODE;
iput(ip); f->ip = iunlock(ip);
return -1; f->off = 0;
}
if((fd = fdalloc(f)) < 0){
iput(ip);
fileclose(f);
return -1;
}
iunlock(ip);
f->type = FD_FILE;
if(omode & O_RDWR) { if(omode & O_RDWR) {
f->readable = 1; f->readable = 1;
f->writable = 1; f->writable = 1;
@ -156,8 +284,6 @@ sys_open(void)
f->readable = 1; f->readable = 1;
f->writable = 0; f->writable = 0;
} }
f->ip = ip;
f->off = 0;
return fd; return fd;
} }
@ -165,7 +291,7 @@ sys_open(void)
int int
sys_mknod(void) sys_mknod(void)
{ {
struct inode *nip; struct inode *ip;
char *path; char *path;
int len; int len;
int type, major, minor; int type, major, minor;
@ -173,14 +299,10 @@ sys_mknod(void)
if((len=argstr(0, &path)) < 0 || argint(1, &type) < 0 || if((len=argstr(0, &path)) < 0 || argint(1, &type) < 0 ||
argint(2, &major) < 0 || argint(3, &minor) < 0) argint(2, &major) < 0 || argint(3, &minor) < 0)
return -1; return -1;
// XXX check that type == T_DEV or eliminate type arg?
// XXX why this check? if((ip = mkpath(path, 0, type, major, minor)) == 0)
if(len >= DIRSIZ)
return -1; return -1;
iput(iunlock(ip));
if((nip = mknod(path, type, major, minor)) == 0)
return -1;
iput(nip);
return 0; return 0;
} }
@ -188,56 +310,31 @@ int
sys_mkdir(void) sys_mkdir(void)
{ {
char *path; char *path;
struct inode *ip;
if(argstr(0, &path) < 0) if(argstr(0, &path) < 0 || (ip = mkpath(path, 0, T_DIR, 0, 0)) == 0)
return -1; return -1;
return mkdir(path); iput(iunlock(ip));
return 0;
} }
int int
sys_chdir(void) sys_chdir(void)
{ {
struct inode *ip;
char *path; char *path;
struct inode *ip;
if(argstr(0, &path) < 0) if(argstr(0, &path) < 0 || (ip = ilock(namei(path))) == 0)
return -1; return -1;
if((ip = namei(path)) == 0)
return -1;
if(ip->type != T_DIR) { if(ip->type != T_DIR) {
iput(ip); iput(iunlock(ip));
return -1; return -1;
} }
iput(cp->cwd);
iunlock(ip); cp->cwd = iunlock(ip);
idecref(cp->cwd);
cp->cwd = ip;
return 0; return 0;
} }
int
sys_unlink(void)
{
char *path;
if(argstr(0, &path) < 0)
return -1;
return unlink(path);
}
int
sys_fstat(void)
{
struct file *f;
struct stat *st;
if(argfd(0, 0, &f) < 0 || argptr(1, (void*)&st, sizeof *st) < 0)
return -1;
return filestat(f, st);
}
int int
sys_dup(void) sys_dup(void)
{ {
@ -252,30 +349,18 @@ sys_dup(void)
return fd; return fd;
} }
int
sys_link(void)
{
char *old, *new;
if(argstr(0, &old) < 0 || argstr(1, &new) < 0)
return -1;
return link(old, new);
}
#define MAXARGS 20
int int
sys_exec(void) sys_exec(void)
{ {
char *path, *argv[MAXARGS]; char *path, *argv[20];
int i; int i;
uint uargv, uarg; uint uargv, uarg;
if(argstr(0, &path) < 0 || argint(1, (int*)&uargv) < 0) if(argstr(0, &path) < 0 || argint(1, (int*)&uargv) < 0)
return -1; return -1;
memset(argv, 0, sizeof argv); memset(argv, 0, sizeof(argv));
for(i=0;; i++){ for(i=0;; i++){
if(i >= MAXARGS) if(i >= NELEM(argv))
return -1; return -1;
if(fetchint(cp, uargv+4*i, (int*)&uarg) < 0) if(fetchint(cp, uargv+4*i, (int*)&uarg) < 0)
return -1; return -1;
@ -289,3 +374,26 @@ sys_exec(void)
return exec(path, argv); return exec(path, argv);
} }
int
sys_pipe(void)
{
int *fd;
struct file *rf, *wf;
int fd0, fd1;
if(argptr(0, (void*)&fd, 2*sizeof(fd[0])) < 0)
return -1;
if(pipe_alloc(&rf, &wf) < 0)
return -1;
fd0 = -1;
if((fd0 = fdalloc(rf)) < 0 || (fd1 = fdalloc(wf)) < 0){
if(fd0 >= 0)
cp->ofile[fd0] = 0;
fileclose(rf);
fileclose(wf);
return -1;
}
fd[0] = fd0;
fd[1] = fd1;
return 0;
}

8
trap.c
View File

@ -17,14 +17,14 @@ tvinit(void)
int i; int i;
for(i = 0; i < 256; i++) for(i = 0; i < 256; i++)
SETGATE(idt[i], 0, SEG_KCODE << 3, vectors[i], 0); SETGATE(idt[i], 0, SEG_KCODE<<3, vectors[i], 0);
SETGATE(idt[T_SYSCALL], 0, SEG_KCODE << 3, vectors[T_SYSCALL], DPL_USER); SETGATE(idt[T_SYSCALL], 0, SEG_KCODE<<3, vectors[T_SYSCALL], DPL_USER);
} }
void void
idtinit(void) idtinit(void)
{ {
lidt(idt, sizeof idt); lidt(idt, sizeof(idt));
} }
void void
@ -80,7 +80,7 @@ trap(struct trapframe *tf)
default: default:
if(cp) { if(cp) {
// Assume process divided by zero or dereferenced null, etc. // Assume process divided by zero or dereferenced null, etc.
cprintf("pid %d %s: unhandled trap %d err %d on cpu %d eip %x -- kill proc\n", cprintf("pid %d %s: trap %d err %d on cpu %d eip %x -- kill proc\n",
cp->pid, cp->name, tf->trapno, tf->err, cpu(), tf->eip); cp->pid, cp->name, tf->trapno, tf->err, cpu(), tf->eip);
proc_exit(); proc_exit();
} }

3
trapasm.S
View File

@ -33,6 +33,3 @@ forkret1:
movl 4(%esp), %esp movl 4(%esp), %esp
jmp trapret jmp trapret
.globl acpu
acpu:
.long 0

12
ulib.c
View File

@ -100,3 +100,15 @@ atoi(const char *s)
n = n*10 + *s++ - '0'; n = n*10 + *s++ - '0';
return n; return n;
} }
void*
memmove(void *vdst, void *vsrc, int n)
{
char *dst, *src;
dst = vdst;
src = vsrc;
while(n-- > 0)
*dst++ = *src++;
return vdst;
}

1
user.h
View File

@ -23,6 +23,7 @@ char* sbrk(int);
int stat(char*, struct stat*); int stat(char*, struct stat*);
int puts(char*); int puts(char*);
char* strcpy(char*, char*); char* strcpy(char*, char*);
void *memmove(void*, void*, int);
char* strchr(const char*, char c); char* strchr(const char*, char c);
int strcmp(const char*, const char*); int strcmp(const char*, const char*);
void printf(int, char*, ...); void printf(int, char*, ...);

21
vectors.pl
View File

@ -26,3 +26,24 @@ print "vectors:\n";
for(my $i = 0; $i < 256; $i++){ for(my $i = 0; $i < 256; $i++){
print " .long vector$i\n"; print " .long vector$i\n";
} }
# sample output:
# # handlers
# .text
# .globl alltraps
# .globl vector0
# vector0:
# pushl $0
# pushl $0
# jmp alltraps
# ...
#
# # vector table
# .data
# .globl vectors
# vectors:
# .long vector0
# .long vector1
# .long vector2
# ...