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xv6: formatting, cleanup, rev5 (take 2)

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This commit is contained in:
Russ Cox 2011-02-19 21:17:55 -05:00
parent 9c4fe7ba10
commit cf4b1ad90b
17 changed files with 193 additions and 197 deletions
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20
Makefile
View file

@ -107,8 +107,8 @@ initcode: initcode.S
$(OBJCOPY) -S -O binary initcode.out initcode
$(OBJDUMP) -S initcode.o > initcode.asm
kernel: $(OBJS) multiboot.o bootother initcode
$(LD) $(LDFLAGS) -Ttext 0x100000 -e main -o kernel multiboot.o $(OBJS) -b binary initcode bootother fs.img
kernel: $(OBJS) multiboot.o data.o bootother initcode
$(LD) $(LDFLAGS) -Ttext 0x100000 -e main -o kernel multiboot.o data.o $(OBJS) -b binary initcode bootother
$(OBJDUMP) -S kernel > kernel.asm
$(OBJDUMP) -t kernel | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > kernel.sym
@ -119,8 +119,8 @@ kernel: $(OBJS) multiboot.o bootother initcode
# great for testing the kernel on real hardware without
# needing a scratch disk.
MEMFSOBJS = $(filter-out ide.o,$(OBJS)) memide.o
kernelmemfs: $(MEMFSOBJS) multiboot.o bootother initcode fs.img
$(LD) $(LDFLAGS) -Ttext 0x100000 -e main -o kernelmemfs multiboot.o $(MEMFSOBJS) -b binary initcode bootother fs.img
kernelmemfs: $(MEMFSOBJS) multiboot.o data.o bootother initcode fs.img
$(LD) $(LDFLAGS) -Ttext 0x100000 -e main -o kernelmemfs multiboot.o data.o $(MEMFSOBJS) -b binary initcode bootother fs.img
$(OBJDUMP) -S kernelmemfs > kernelmemfs.asm
$(OBJDUMP) -t kernelmemfs | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > kernelmemfs.sym
@ -251,14 +251,16 @@ dist-test:
rm -rf dist-test
mkdir dist-test
cp dist/* dist-test
cd dist-test; ../m print
cd dist-test; ../m bochs || true
cd dist-test; ../m qemu
cd dist-test; $(MAKE) print
cd dist-test; $(MAKE) bochs || true
cd dist-test; $(MAKE) qemu
# update this rule (change rev1) when it is time to
# update this rule (change rev#) when it is time to
# make a new revision.
tar:
rm -rf /tmp/xv6
mkdir -p /tmp/xv6
cp dist/* dist/.gdbinit.tmpl /tmp/xv6
(cd /tmp; tar cf - xv6) | gzip >xv6-rev4.tar.gz
(cd /tmp; tar cf - xv6) | gzip >xv6-rev5.tar.gz
.PHONY: dist-test dist

29
bootasm.S
View file

@ -21,10 +21,8 @@ start:
movw %ax,%es # -> Extra Segment
movw %ax,%ss # -> Stack Segment
# Enable A20:
# For backwards compatibility with the earliest PCs, physical
# address line 20 is tied low, so that addresses higher than
# 1MB wrap around to zero by default. This code undoes this.
# Physical address line A20 is tied to zero so that the first PCs
# with 2 MB would run software that assumed 1 MB. Undo that.
seta20.1:
inb $0x64,%al # Wait for not busy
testb $0x2,%al
@ -41,28 +39,21 @@ seta20.2:
movb $0xdf,%al # 0xdf -> port 0x60
outb %al,$0x60
//PAGEBREAK!
# Switch from real to protected mode, using a bootstrap GDT
# and segment translation that makes virtual addresses
# identical to physical addresses, so that the
# effective memory map does not change after subsequent
# loads of segment registers.
# Switch from real to protected mode. Use a bootstrap GDT that makes
# virtual addresses map dierctly to physical addresses so that the
# effective memory map doesn't change during the transition.
lgdt gdtdesc
movl %cr0, %eax
orl $CR0_PE, %eax
movl %eax, %cr0
# This ljmp is how you load the CS (Code Segment) register.
# SEG_ASM produces segment descriptors with the 32-bit mode
# flag set (the D flag), so addresses and word operands will
# default to 32 bits after this jump.
//PAGEBREAK!
# Complete transition to 32-bit protected mode by using long jmp
# to reload %cs and %eip. The segment registers are set up with no
# translation, so that the mapping is still the identity mapping.
ljmp $(SEG_KCODE<<3), $start32
# tell the assembler to generate 0x66 prefixes for 16-bit
# instructions like movw, and to generate 32-bit immediate
# addresses.
.code32
.code32 # Tell assembler to generate 32-bit code now.
start32:
# Set up the protected-mode data segment registers
movw $(SEG_KDATA<<3), %ax # Our data segment selector

2
bootother.S
View file

@ -34,12 +34,12 @@ start:
movw %ax,%es
movw %ax,%ss
//PAGEBREAK!
lgdt gdtdesc
movl %cr0, %eax
orl $CR0_PE, %eax
movl %eax, %cr0
//PAGEBREAK!
ljmp $(SEG_KCODE<<3), $start32
.code32

23
data.S
View file

@ -1,5 +1,24 @@
# Define "data" symbol to mark beginning of data segment.
# Must be linked before any other data on ld command line.
// The kernel layout is:
//
// text
// rodata
// data
// bss
//
// Conventionally, Unix linkers provide pseudo-symbols
// etext, edata, and end, at the end of the text, data, and bss.
// For the kernel mapping, we need the address at the beginning
// of the data section, but that's not one of the conventional
// symbols, because the convention started before there was a
// read-only rodata section between text and data.
//
// To get the address of the data section, we define a symbol
// named data and make sure this is the first object passed to
// the linker, so that it will be the first symbol in the data section.
//
// Alternative approaches would be to parse our own ELF header
// or to write a linker script, but this is simplest.
.data
.globl data
data:

56
exec.c
View file

@ -10,8 +10,8 @@ int
exec(char *path, char **argv)
{
char *s, *last;
int i, off, argc;
uint sz, sp, strings[MAXARG];
int i, off;
uint argc, sz, sp, ustack[3+MAXARG+1];
struct elfhdr elf;
struct inode *ip;
struct proghdr ph;
@ -53,49 +53,25 @@ exec(char *path, char **argv)
if((sz = allocuvm(pgdir, sz, sz + PGSIZE)) == 0)
goto bad;
// initialize stack content:
// "argumentN" -- nul-terminated string
// ...
// "argument0"
// 0 -- argv[argc]
// address of argumentN
// ...
// address of argument0 -- argv[0]
// address of address of argument0 -- argv argument to main()
// argc -- argc argument to main()
// ffffffff -- return PC for main() call
// Push argument strings, prepare rest of stack in ustack.
sp = sz;
// count arguments
for(argc = 0; argv[argc]; argc++)
;
for(argc = 0; argv[argc]; argc++) {
if(argc >= MAXARG)
goto bad;
// push strings and remember where they are
for(i = argc - 1; i >= 0; --i){
sp -= strlen(argv[i]) + 1;
strings[i] = sp;
copyout(pgdir, sp, argv[i], strlen(argv[i]) + 1);
sp -= strlen(argv[argc]) + 1;
sp &= ~3;
if(copyout(pgdir, sp, argv[argc], strlen(argv[argc]) + 1) < 0)
goto bad;
ustack[3+argc] = sp;
}
ustack[3+argc] = 0;
#define PUSH(x){ int xx = (int)(x); sp -= 4; copyout(pgdir, sp, &xx, 4); }
ustack[0] = 0xffffffff; // fake return PC
ustack[1] = argc;
ustack[2] = sp - (argc+1)*4; // argv pointer
PUSH(0); // argv[argc] is zero
// push argv[] elements
for(i = argc - 1; i >= 0; --i)
PUSH(strings[i]);
PUSH(sp); // argv
PUSH(argc);
PUSH(0xffffffff); // in case main tries to return
if(sp < sz - PGSIZE)
sp -= (3+argc+1) * 4;
if(copyout(pgdir, sp, ustack, (3+argc+1)*4) < 0)
goto bad;
// Save program name for debugging.
@ -110,9 +86,7 @@ exec(char *path, char **argv)
proc->sz = sz;
proc->tf->eip = elf.entry; // main
proc->tf->esp = sp;
switchuvm(proc);
freevm(oldpgdir);
return 0;

1
fs.h
View file

@ -41,7 +41,6 @@ struct dinode {
// Block containing bit for block b
#define BBLOCK(b, ninodes) (b/BPB + (ninodes)/IPB + 3)
// PAGEBREAK: 10
// Directory is a file containing a sequence of dirent structures.
#define DIRSIZ 14

2
ide.c
View file

@ -96,7 +96,7 @@ ideintr(void)
acquire(&idelock);
if((b = idequeue) == 0){
release(&idelock);
cprintf("Spurious IDE interrupt.\n");
// cprintf("spurious IDE interrupt\n");
return;
}
idequeue = b->qnext;

7
main.c
View file

@ -89,7 +89,8 @@ bootothers(void)
char *stack;
// Write bootstrap code to unused memory at 0x7000.
// The linker has placed the image of bootother.S in _binary_bootother_start.
// The linker has placed the image of bootother.S in
// _binary_bootother_start.
code = (uchar*)0x7000;
memmove(code, _binary_bootother_start, (uint)_binary_bootother_size);
@ -111,3 +112,7 @@ bootothers(void)
;
}
}
//PAGEBREAK!
// Blank page.

2
mp.c
View file

@ -39,7 +39,6 @@ mpsearch1(uchar *addr, int len)
{
uchar *e, *p;
cprintf("mpsearch1 0x%x %d\n", addr, len);
e = addr+len;
for(p = addr; p < e; p += sizeof(struct mp))
if(memcmp(p, "_MP_", 4) == 0 && sum(p, sizeof(struct mp)) == 0)
@ -113,7 +112,6 @@ mpinit(void)
switch(*p){
case MPPROC:
proc = (struct mpproc*)p;
cprintf("mpproc %d\n", proc->apicid);
if(ncpu != proc->apicid){
cprintf("mpinit: ncpu=%d apicid=%d\n", ncpu, proc->apicid);
ismp = 0;

76
proc.c
View file

@ -25,44 +25,6 @@ pinit(void)
initlock(&ptable.lock, "ptable");
}
//PAGEBREAK: 36
// Print a process listing to console. For debugging.
// Runs when user types ^P on console.
// No lock to avoid wedging a stuck machine further.
void
procdump(void)
{
static char *states[] = {
[UNUSED] "unused",
[EMBRYO] "embryo",
[SLEEPING] "sleep ",
[RUNNABLE] "runble",
[RUNNING] "run ",
[ZOMBIE] "zombie"
};
int i;
struct proc *p;
char *state;
uint pc[10];
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
if(p->state == UNUSED)
continue;
if(p->state >= 0 && p->state < NELEM(states) && states[p->state])
state = states[p->state];
else
state = "???";
cprintf("%d %s %s", p->pid, state, p->name);
if(p->state == SLEEPING){
getcallerpcs((uint*)p->context->ebp+2, pc);
for(i=0; i<10 && pc[i] != 0; i++)
cprintf(" %p", pc[i]);
}
cprintf("\n");
}
}
//PAGEBREAK: 32
// Look in the process table for an UNUSED proc.
// If found, change state to EMBRYO and initialize
@ -447,3 +409,41 @@ kill(int pid)
return -1;
}
//PAGEBREAK: 36
// Print a process listing to console. For debugging.
// Runs when user types ^P on console.
// No lock to avoid wedging a stuck machine further.
void
procdump(void)
{
static char *states[] = {
[UNUSED] "unused",
[EMBRYO] "embryo",
[SLEEPING] "sleep ",
[RUNNABLE] "runble",
[RUNNING] "run ",
[ZOMBIE] "zombie"
};
int i;
struct proc *p;
char *state;
uint pc[10];
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
if(p->state == UNUSED)
continue;
if(p->state >= 0 && p->state < NELEM(states) && states[p->state])
state = states[p->state];
else
state = "???";
cprintf("%d %s %s", p->pid, state, p->name);
if(p->state == SLEEPING){
getcallerpcs((uint*)p->context->ebp+2, pc);
for(i=0; i<10 && pc[i] != 0; i++)
cprintf(" %p", pc[i]);
}
cprintf("\n");
}
}

4
runoff.list
View file

@ -22,6 +22,7 @@ proc.h
proc.c
swtch.S
kalloc.c
data.S
vm.c
# system calls
traps.h
@ -48,6 +49,7 @@ exec.c
# pipes
pipe.c
# string operations
string.c
@ -62,6 +64,7 @@ kbd.c
console.c
timer.c
uart.c
multiboot.S
# user-level
initcode.S
@ -72,3 +75,4 @@ sh.c

26
runoff.spec
View file

@ -6,8 +6,8 @@ sheet1: left
# pages. The file may start in either column.
#
# "even" and "odd" specify which column a file must start on. "even"
# means it must start in the left of the two columns. "odd" means it
# must start in the right of the two columns.
# means it must start in the left of the two columns (00). "odd" means it
# must start in the right of the two columns (50).
#
# You'd think these would be the other way around.
@ -33,23 +33,23 @@ left: spinlock.h # mild preference
even: spinlock.h # mild preference
# This gets struct proc and allocproc on the same spread
right: proc.h
odd: proc.h
left: proc.h
even: proc.h
# goal is to have two action-packed 2-page spreads,
# one with
# userinit growproc fork exit wait
# and another with
# scheduler sched yield forkret sleep wakeup1 wakeup
left: proc.c # VERY important
odd: proc.c # VERY important
right: proc.c # VERY important
even: proc.c # VERY important
# A few more action packed spreads
# page table creation and process loading
# walkpgdir mappages setupkvm vmenable switch[ku]vm inituvm loaduvm
# process memory management
# allocuvm deallocuvm freevm
right: vm.c
left: vm.c
odd: vm.c
# kalloc.c either
@ -69,17 +69,25 @@ odd: vm.c
# file.h either
# fs.h either
# fsvar.h either
left: ide.c
# left: ide.c # mild preference
even: ide.c
# odd: bio.c
# with fs.c starting on 2nd column of a left page, we get these 2-page spreads:
# ialloc iupdate iget idup ilock iunlock iput iunlockput
# bmap itrunc stati readi writei
# namecmp dirlookup dirlink skipelem namex namei
# fielinit filealloc filedup fileclose filestat fileread filewrite
# starting on 2nd column of a right page is not terrible either
odd: fs.c # VERY important
left: fs.c # mild preference
# file.c either
# exec.c either
# sysfile.c either
# even: pipe.c # mild preference
# string.c either
left: kbd.h
# left: kbd.h # mild preference
even: kbd.h
even: console.c
odd: sh.c

2
runoff1
View file

@ -33,7 +33,7 @@ for($i=0; $i<@lines; ){
last if $i>=@lines;
# If the rest of the file fits, use the whole thing.
if(@lines <= $i+50){
if(@lines <= $i+50 && !grep { /PAGEBREAK/ } @lines){
$breakbefore = @lines;
}else{
# Find a good next page break;

6
toc.ftr
View file

@ -6,8 +6,8 @@ on the same line as the name, the line number (or, in a few cases, numbers)
where the name is defined. Successive lines in an entry list the line
numbers where the name is used. For example, this entry:
swtch 2308
0317 2128 2166 2307 2308
swtch 2358
0317 2128 2166 2357 2358
indicates that swtch is defined on line 2308 and is mentioned on five lines
indicates that swtch is defined on line 2358 and is mentioned on five lines
on sheets 03, 21, and 23.

3
trap.c
View file

@ -59,6 +59,9 @@ trap(struct trapframe *tf)
ideintr();
lapiceoi();
break;
case T_IRQ0 + IRQ_IDE+1:
// Bochs generates spurious IDE1 interrupts.
break;
case T_IRQ0 + IRQ_KBD:
kbdintr();
lapiceoi();

6
usertests.c
View file

@ -1445,11 +1445,11 @@ bigargtest(void)
ppid = getpid();
pid = fork();
if(pid == 0){
char *args[32];
char *args[32+1];
int i;
for(i = 0; i < 32-1; i++)
for(i = 0; i < 32; i++)
args[i] = "bigargs test: failed\n ";
args[32-1] = 0;
args[32] = 0;
printf(stdout, "bigarg test\n");
exec("echo", args);
printf(stdout, "bigarg test ok\n");

113
vm.c
View file

@ -6,8 +6,18 @@
#include "proc.h"
#include "elf.h"
extern char data[]; // defined in data.S
static pde_t *kpgdir; // for use in scheduler()
// Allocate one page table for the machine for the kernel address
// space for scheduler processes.
void
kvmalloc(void)
{
kpgdir = setupkvm();
}
// Set up CPU's kernel segment descriptors.
// Run once at boot time on each CPU.
void
@ -72,7 +82,6 @@ mappages(pde_t *pgdir, void *la, uint size, uint pa, int perm)
a = PGROUNDDOWN(la);
last = PGROUNDDOWN(la + size - 1);
for(;;){
pte = walkpgdir(pgdir, a, 1);
if(pte == 0)
@ -110,40 +119,32 @@ mappages(pde_t *pgdir, void *la, uint size, uint pa, int perm)
// range from 0 till 640KB (USERTOP), which where the I/O hole starts
// (both in physical memory and in the kernel's virtual address
// space).
// Allocate one page table for the machine for the kernel address
// space for scheduler processes.
void
kvmalloc(void)
{
kpgdir = setupkvm();
}
static struct kmap {
void *p;
void *e;
int perm;
} kmap[] = {
{(void*)USERTOP, (void*)0x100000, PTE_W}, // I/O space
{(void*)0x100000, data, 0 }, // kernel text, rodata
{data, (void*)PHYSTOP, PTE_W}, // kernel data, memory
{(void*)0xFE000000, 0, PTE_W}, // device mappings
};
// Set up kernel part of a page table.
pde_t*
setupkvm(void)
{
extern char etext[];
char *rwstart;
pde_t *pgdir;
uint rwlen;
struct kmap *k;
rwstart = PGROUNDDOWN(etext);
rwlen = (uint)rwstart - 0x100000;
// Allocate page directory
if((pgdir = (pde_t*)kalloc()) == 0)
return 0;
memset(pgdir, 0, PGSIZE);
if(// Map IO space from 640K to 1Mbyte
mappages(pgdir, (void*)USERTOP, 0x60000, USERTOP, PTE_W) < 0 ||
// Map kernel instructions
mappages(pgdir, (void*)0x100000, rwlen, 0x100000, 0) < 0 ||
// Map kernel data and free memory pool
mappages(pgdir, rwstart, PHYSTOP-(uint)rwstart, (uint)rwstart, PTE_W) < 0 ||
// Map devices such as ioapic, lapic, ...
mappages(pgdir, (void*)0xFE000000, 0x2000000, 0xFE000000, PTE_W) < 0)
k = kmap;
for(k = kmap; k < &kmap[NELEM(kmap)]; k++)
if(mappages(pgdir, k->p, k->e - k->p, (uint)k->p, k->perm) < 0)
return 0;
return pgdir;
}
@ -162,48 +163,27 @@ vmenable(void)
// Switch h/w page table register to the kernel-only page table,
// for when no process is running.
void
switchkvm()
switchkvm(void)
{
lcr3(PADDR(kpgdir)); // switch to the kernel page table
}
// Switch h/w page table and TSS registers to point to process p.
// Switch TSS and h/w page table to correspond to process p.
void
switchuvm(struct proc *p)
{
pushcli();
// Setup TSS
cpu->gdt[SEG_TSS] = SEG16(STS_T32A, &cpu->ts, sizeof(cpu->ts)-1, 0);
cpu->gdt[SEG_TSS].s = 0;
cpu->ts.ss0 = SEG_KDATA << 3;
cpu->ts.esp0 = (uint)proc->kstack + KSTACKSIZE;
ltr(SEG_TSS << 3);
if(p->pgdir == 0)
panic("switchuvm: no pgdir\n");
panic("switchuvm: no pgdir");
lcr3(PADDR(p->pgdir)); // switch to new address space
popcli();
}
// Return the physical address that a given user address
// maps to. The result is also a kernel logical address,
// since the kernel maps the physical memory allocated to user
// processes directly.
char*
uva2ka(pde_t *pgdir, char *uva)
{
pte_t *pte;
pte = walkpgdir(pgdir, uva, 0);
if((*pte & PTE_P) == 0)
return 0;
if((*pte & PTE_U) == 0)
return 0;
return (char*)PTE_ADDR(*pte);
}
// Load the initcode into address 0 of pgdir.
// sz must be less than a page.
void
@ -228,10 +208,10 @@ loaduvm(pde_t *pgdir, char *addr, struct inode *ip, uint offset, uint sz)
pte_t *pte;
if((uint)addr % PGSIZE != 0)
panic("loaduvm: addr must be page aligned\n");
panic("loaduvm: addr must be page aligned");
for(i = 0; i < sz; i += PGSIZE){
if((pte = walkpgdir(pgdir, addr+i, 0)) == 0)
panic("loaduvm: address should exist\n");
panic("loaduvm: address should exist");
pa = PTE_ADDR(*pte);
if(sz - i < PGSIZE)
n = sz - i;
@ -243,10 +223,8 @@ loaduvm(pde_t *pgdir, char *addr, struct inode *ip, uint offset, uint sz)
return 0;
}
// Allocate memory to the process to bring its size from oldsz to
// newsz. Allocates physical memory and page table entries. oldsz and
// newsz need not be page-aligned, nor does newsz have to be larger
// than oldsz. Returns the new process size or 0 on error.
// Allocate page tables and physical memory to grow process from oldsz to
// newsz, which need not be page aligned. Returns new size or 0 on error.
int
allocuvm(pde_t *pgdir, uint oldsz, uint newsz)
{
@ -330,9 +308,9 @@ copyuvm(pde_t *pgdir, uint sz)
return 0;
for(i = 0; i < sz; i += PGSIZE){
if((pte = walkpgdir(pgdir, (void*)i, 0)) == 0)
panic("copyuvm: pte should exist\n");
panic("copyuvm: pte should exist");
if(!(*pte & PTE_P))
panic("copyuvm: page not present\n");
panic("copyuvm: page not present");
pa = PTE_ADDR(*pte);
if((mem = kalloc()) == 0)
goto bad;
@ -347,16 +325,31 @@ bad:
return 0;
}
// copy some data to user address va in page table pgdir.
// most useful when pgdir is not the current page table.
//PAGEBREAK!
// Map user virtual address to kernel physical address.
char*
uva2ka(pde_t *pgdir, char *uva)
{
pte_t *pte;
pte = walkpgdir(pgdir, uva, 0);
if((*pte & PTE_P) == 0)
return 0;
if((*pte & PTE_U) == 0)
return 0;
return (char*)PTE_ADDR(*pte);
}
// Copy len bytes from p to user address va in page table pgdir.
// Most useful when pgdir is not the current page table.
// uva2ka ensures this only works for PTE_U pages.
int
copyout(pde_t *pgdir, uint va, void *xbuf, uint len)
copyout(pde_t *pgdir, uint va, void *p, uint len)
{
char *buf, *pa0;
uint n, va0;
buf = (char*)xbuf;
buf = (char*)p;
while(len > 0){
va0 = (uint)PGROUNDDOWN(va);
pa0 = uva2ka(pgdir, (char*)va0);