Update sources to upstream mit-pdos version (#39)

.gitignore

@@ -15,6 +15,7 @@ mkfs
 kernel/kernel
 user/usys.S
 .gdbinit
+TAGS
 
 # Clangd
 compile_commands.json

Makefile

@@ -53,17 +53,18 @@ TOOLPREFIX := $(shell if riscv64-unknown-elf-objdump -i 2>&1 | grep 'elf64-big'
 endif
 
 QEMU = qemu-system-riscv64
+MIN_QEMU_VERSION = 7.2
 
 CC = $(TOOLPREFIX)gcc
 AS = $(TOOLPREFIX)gas
 LD = $(TOOLPREFIX)ld
 OBJCOPY = $(TOOLPREFIX)objcopy
 OBJDUMP = $(TOOLPREFIX)objdump
 
-CFLAGS = -Wall -Werror -O -fno-omit-frame-pointer -ggdb -gdwarf-2
+CFLAGS = -Wall -Werror -Wno-unknown-attributes -O -fno-omit-frame-pointer -ggdb -gdwarf-2
 CFLAGS += -MD
 CFLAGS += -mcmodel=medany
-# CFLAGS += -ffreestanding -fno-common -nostdlib -mno-relax
+CFLAGS += -ffreestanding
 CFLAGS += -fno-common -nostdlib
 CFLAGS += -fno-builtin-strncpy -fno-builtin-strncmp -fno-builtin-strlen -fno-builtin-memset
 CFLAGS += -fno-builtin-memmove -fno-builtin-memcmp -fno-builtin-log -fno-builtin-bzero
@@ -84,24 +85,21 @@ endif
 
 LDFLAGS = -z max-page-size=4096
 
-$K/kernel: $(OBJS) $K/kernel.ld $U/initcode
+$K/kernel: $(OBJS) $K/kernel.ld
 	$(LD) $(LDFLAGS) -T $K/kernel.ld -o $K/kernel $(OBJS) 
 	$(OBJDUMP) -S $K/kernel > $K/kernel.asm
 	$(OBJDUMP) -t $K/kernel | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > $K/kernel.sym
 
-$U/initcode: $U/initcode.S
-	$(CC) $(CFLAGS) -march=rv64g -nostdinc -I. -Ikernel -c $U/initcode.S -o $U/initcode.o
-	$(LD) $(LDFLAGS) -N -e start -Ttext 0 -o $U/initcode.out $U/initcode.o
-	$(OBJCOPY) -S -O binary $U/initcode.out $U/initcode
-	$(OBJDUMP) -S $U/initcode.o > $U/initcode.asm
+$K/%.o: $K/%.S
+	$(CC) -g -c -o $@ $<
 
-tags: $(OBJS) _init
-	etags *.S *.c
+tags: $(OBJS)
+	etags kernel/*.S kernel/*.c
 
 ULIB = $U/ulib.o $U/usys.o $U/printf.o $U/umalloc.o
 
-_%: %.o $(ULIB)
-	$(LD) $(LDFLAGS) -T $U/user.ld -o $@ $^
+_%: %.o $(ULIB) $U/user.ld
+	$(LD) $(LDFLAGS) -T $U/user.ld -o $@ $< $(ULIB)
 	$(OBJDUMP) -S $@ > $*.asm
 	$(OBJDUMP) -t $@ | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > $*.sym
 
@@ -128,7 +126,7 @@ $U/dump2tests.o: $U/dump2tests.S $U/dump2tests.c $K/syscall.h
 	$(LD) -r $U/dump2tests.c.o $U/dump2tests.s.o -o $U/dump2tests.o
 
 mkfs/mkfs: mkfs/mkfs.c $K/fs.h $K/param.h
-	gcc -Werror -Wall -I. -o mkfs/mkfs mkfs/mkfs.c
+	gcc -Wno-unknown-attributes -I. -o mkfs/mkfs mkfs/mkfs.c
 
 # Prevent deletion of intermediate files, e.g. cat.o, after first build, so
 # that disk image changes after first build are persistent until clean.  More
@@ -153,6 +151,11 @@ UPROGS=\
 	$U/_grind\
 	$U/_wc\
 	$U/_zombie\
+	$U/_logstress\
+	$U/_forphan\
+	$U/_dorphan\
+
+UPROGS+=\
 	$U/_dumptests\
 	$U/_dump2tests\
 	$U/_alloctest\
@@ -167,7 +170,7 @@ fs.img: mkfs/mkfs README $(UPROGS)
 clean: 
 	rm -f *.tex *.dvi *.idx *.aux *.log *.ind *.ilg \
 	*/*.o */*.d */*.asm */*.sym \
-	$U/initcode $U/initcode.out $K/kernel fs.img \
+	$K/kernel fs.img \
 	mkfs/mkfs .gdbinit \
         $U/usys.S \
 	$(UPROGS)
@@ -187,7 +190,7 @@ QEMUOPTS += -global virtio-mmio.force-legacy=false
 QEMUOPTS += -drive file=fs.img,if=none,format=raw,id=x0
 QEMUOPTS += -device virtio-blk-device,drive=x0,bus=virtio-mmio-bus.0
 
-qemu: $K/kernel fs.img
+qemu: check-qemu-version $K/kernel fs.img
 	$(QEMU) $(QEMUOPTS)
 
 .gdbinit: .gdbinit.tmpl-riscv
@@ -197,3 +200,12 @@ qemu-gdb: $K/kernel .gdbinit fs.img
 	@echo "*** Now run 'gdb' in another window." 1>&2
 	$(QEMU) $(QEMUOPTS) -S $(QEMUGDB)
 
+print-gdbport:
+	@echo $(GDBPORT)
+
+QEMU_VERSION := $(shell $(QEMU) --version | head -n 1 | sed -E 's/^QEMU emulator version ([0-9]+\.[0-9]+)\..*/\1/')
+check-qemu-version:
+	@if [ "$(shell echo "$(QEMU_VERSION) >= $(MIN_QEMU_VERSION)" | bc)" -eq 0 ]; then \
+		echo "ERROR: Need qemu version >= $(MIN_QEMU_VERSION)"; \
+		exit 1; \
+	fi

README

@@ -14,22 +14,24 @@ locking), Cliff Frey (MP), Xiao Yu (MP), Nickolai Zeldovich, and Austin
 Clements.
 
 We are also grateful for the bug reports and patches contributed by
-Takahiro Aoyagi, Marcelo Arroyo, Silas Boyd-Wickizer, Anton Burtsev,
-carlclone, Ian Chen, Dan Cross, Cody Cutler, Mike CAT, Tej Chajed,
-Asami Doi,Wenyang Duan, eyalz800, Nelson Elhage, Saar Ettinger, Alice
-Ferrazzi, Nathaniel Filardo, flespark, Peter Froehlich, Yakir Goaron,
-Shivam Handa, Matt Harvey, Bryan Henry, jaichenhengjie, Jim Huang,
-Matúš Jókay, John Jolly, Alexander Kapshuk, Anders Kaseorg, kehao95,
+Abhinavpatel00, Takahiro Aoyagi, Marcelo Arroyo, Hirbod Behnam, Silas
+Boyd-Wickizer, Anton Burtsev, carlclone, Ian Chen, clivezeng, Dan
+Cross, Cody Cutler, Mike CAT, Tej Chajed, Asami Doi,Wenyang Duan,
+echtwerner, eyalz800, Nelson Elhage, Saar Ettinger, Alice Ferrazzi,
+Nathaniel Filardo, flespark, Peter Froehlich, Yakir Goaron, Shivam
+Handa, Matt Harvey, Bryan Henry, jaichenhengjie, Jim Huang, Matúš
+Jókay, John Jolly, Alexander Kapshuk, Anders Kaseorg, kehao95,
 Wolfgang Keller, Jungwoo Kim, Jonathan Kimmitt, Eddie Kohler, Vadim
 Kolontsov, Austin Liew, l0stman, Pavan Maddamsetti, Imbar Marinescu,
-Yandong Mao, Matan Shabtay, Hitoshi Mitake, Carmi Merimovich, Mark
-Morrissey, mtasm, Joel Nider, Hayato Ohhashi, OptimisticSide,
-phosphagos, Harry Porter, Greg Price, RayAndrew, Jude Rich, segfault,
-Ayan Shafqat, Eldar Sehayek, Yongming Shen, Fumiya Shigemitsu, snoire,
-Taojie, Cam Tenny, tyfkda, Warren Toomey, Stephen Tu, Alissa Tung,
-Rafael Ubal, Amane Uehara, Pablo Ventura, Xi Wang, WaheedHafez,
-Keiichi Watanabe, Lucas Wolf, Nicolas Wolovick, wxdao, Grant Wu, x653,
-Jindong Zhang, Icenowy Zheng, ZhUyU1997, and Zou Chang Wei.
+Yandong Mao, Matan Shabtay, Hitoshi Mitake, Carmi Merimovich,
+mes900903, Mark Morrissey, mtasm, Joel Nider, Hayato Ohhashi,
+OptimisticSide, papparapa, phosphagos, Harry Porter, Greg Price, Zheng
+qhuo, Quancheng, RayAndrew, Jude Rich, segfault, Ayan Shafqat, Eldar
+Sehayek, Yongming Shen, Fumiya Shigemitsu, snoire, Taojie, Cam Tenny,
+tyfkda, Warren Toomey, Stephen Tu, Alissa Tung, Rafael Ubal, unicornx,
+Amane Uehara, Pablo Ventura, Luc Videau, Xi Wang, WaheedHafez, Keiichi
+Watanabe, Lucas Wolf, Nicolas Wolovick, wxdao, Grant Wu, x653, Andy
+Zhang, Jindong Zhang, Icenowy Zheng, ZhUyU1997, and Zou Chang Wei.
 
 ERROR REPORTS
 

kernel/console.c

@@ -58,13 +58,17 @@ struct {
 int
 consolewrite(int user_src, uint64 src, int n)
 {
-  int i;
-
-  for(i = 0; i < n; i++){
-    char c;
-    if(either_copyin(&c, user_src, src+i, 1) == -1)
+  char buf[32];
+  int i = 0;
+
+  while(i < n){
+    int nn = sizeof(buf);
+    if(nn > n - i)
+      nn = n - i;
+    if(either_copyin(buf, user_src, src+i, nn) == -1)
       break;
-    uartputc(c);
+    uartwrite(buf, nn);
+    i += nn;
   }
 
   return i;

kernel/defs.h

@@ -24,7 +24,7 @@ void            consoleintr(int);
 void            consputc(int);
 
 // exec.c
-int             exec(char*, char**);
+int             kexec(char*, char**);
 
 // file.c
 struct file*    filealloc(void);
@@ -54,11 +54,7 @@ int             readi(struct inode*, int, uint64, uint, uint);
 void            stati(struct inode*, struct stat*);
 int             writei(struct inode*, int, uint64, uint, uint);
 void            itrunc(struct inode*);
-
-// ramdisk.c
-void            ramdiskinit(void);
-void            ramdiskintr(void);
-void            ramdiskrw(struct buf*);
+void            ireclaim(int);
 
 // kalloc.c
 void*           kalloc(void);
@@ -78,30 +74,29 @@ int             piperead(struct pipe*, uint64, int);
 int             pipewrite(struct pipe*, uint64, int);
 
 // printf.c
-int            printf(char*, ...) __attribute__ ((format (printf, 1, 2)));
+int             printf(char*, ...) __attribute__ ((format (printf, 1, 2)));
 void            panic(char*) __attribute__((noreturn));
 void            printfinit(void);
 
 // proc.c
 int             cpuid(void);
-void            exit(int);
-int             fork(void);
+void            kexit(int);
+int             kfork(void);
 int             growproc(int);
 void            proc_mapstacks(pagetable_t);
 pagetable_t     proc_pagetable(struct proc *);
 void            proc_freepagetable(pagetable_t, uint64);
-int             kill(int);
+int             kkill(int);
 int             killed(struct proc*);
 void            setkilled(struct proc*);
 struct cpu*     mycpu(void);
-struct cpu*     getmycpu(void);
 struct proc*    myproc();
 void            procinit(void);
 void            scheduler(void) __attribute__((noreturn));
 void            sched(void);
 void            sleep(void*, struct spinlock*);
 void            userinit(void);
-int             wait(uint64);
+int             kwait(uint64);
 void            wakeup(void*);
 void            yield(void);
 int             either_copyout(int user_dst, uint64 dst, void *src, uint64 len);
@@ -147,12 +142,12 @@ extern uint     ticks;
 void            trapinit(void);
 void            trapinithart(void);
 extern struct spinlock tickslock;
-void            usertrapret(void);
+void            prepare_return(void);
 
 // uart.c
 void            uartinit(void);
 void            uartintr(void);
-void            uartputc(int);
+void            uartwrite(char [], int);
 void            uartputc_sync(int);
 int             uartgetc(void);
 
@@ -162,7 +157,6 @@ void            kvminithart(void);
 void            kvmmap(pagetable_t, uint64, uint64, uint64, int);
 int             mappages(pagetable_t, uint64, uint64, uint64, int);
 pagetable_t     uvmcreate(void);
-void            uvmfirst(pagetable_t, uchar *, uint);
 uint64          uvmalloc(pagetable_t, uint64, uint64, int);
 uint64          uvmdealloc(pagetable_t, uint64, uint64);
 int             uvmcopy(pagetable_t, pagetable_t, uint64);
@@ -174,6 +168,8 @@ uint64          walkaddr(pagetable_t, uint64);
 int             copyout(pagetable_t, uint64, char *, uint64);
 int             copyin(pagetable_t, char *, uint64, uint64);
 int             copyinstr(pagetable_t, char *, uint64, uint64);
+int             ismapped(pagetable_t, uint64);
+uint64          vmfault(pagetable_t, uint64, int);
 
 // plic.c
 void            plicinit(void);

kernel/entry.S

@@ -8,7 +8,7 @@ _entry:
         # set up a stack for C.
         # stack0 is declared in start.c,
         # with a 4096-byte stack per CPU.
-        # sp = stack0 + (hartid * 4096)
+        # sp = stack0 + ((hartid + 1) * 4096)
         la sp, stack0
         li a0, 1024*4
         csrr a1, mhartid

kernel/exec.c

@@ -9,6 +9,7 @@
 
 static int loadseg(pde_t *, uint64, struct inode *, uint, uint);
 
+// map ELF permissions to PTE permission bits.
 int flags2perm(int flags)
 {
     int perm = 0;
@@ -19,8 +20,11 @@ int flags2perm(int flags)
     return perm;
 }
 
+//
+// the implementation of the exec() system call
+//
 int
-exec(char *path, char **argv)
+kexec(char *path, char **argv)
 {
   char *s, *last;
   int i, off;
@@ -33,16 +37,18 @@ exec(char *path, char **argv)
 
   begin_op();
 
+  // Open the executable file.
   if((ip = namei(path)) == 0){
     end_op();
     return -1;
   }
   ilock(ip);
 
-  // Check ELF header
+  // Read the ELF header.
   if(readi(ip, 0, (uint64)&elf, 0, sizeof(elf)) != sizeof(elf))
     goto bad;
 
+  // Is this really an ELF file?
   if(elf.magic != ELF_MAGIC)
     goto bad;
 
@@ -87,7 +93,8 @@ exec(char *path, char **argv)
   sp = sz;
   stackbase = sp - USERSTACK*PGSIZE;
 
-  // Push argument strings, prepare rest of stack in ustack.
+  // Copy argument strings into new stack, remember their
+  // addresses in ustack[].
   for(argc = 0; argv[argc]; argc++) {
     if(argc >= MAXARG)
       goto bad;
@@ -101,15 +108,15 @@ exec(char *path, char **argv)
   }
   ustack[argc] = 0;
 
-  // push the array of argv[] pointers.
+  // push a copy of ustack[], the array of argv[] pointers.
   sp -= (argc+1) * sizeof(uint64);
   sp -= sp % 16;
   if(sp < stackbase)
     goto bad;
   if(copyout(pagetable, sp, (char *)ustack, (argc+1)*sizeof(uint64)) < 0)
     goto bad;
 
-  // arguments to user main(argc, argv)
+  // a0 and a1 contain arguments to user main(argc, argv)
   // argc is returned via the system call return
   // value, which goes in a0.
   p->trapframe->a1 = sp;
@@ -124,7 +131,7 @@ exec(char *path, char **argv)
   oldpagetable = p->pagetable;
   p->pagetable = pagetable;
   p->sz = sz;
-  p->trapframe->epc = elf.entry;  // initial program counter = main
+  p->trapframe->epc = elf.entry;  // initial program counter = ulib.c:start()
   p->trapframe->sp = sp; // initial stack pointer
   proc_freepagetable(oldpagetable, oldsz);
 
@@ -140,7 +147,7 @@ exec(char *path, char **argv)
   return -1;
 }
 
-// Load a program segment into pagetable at virtual address va.
+// Load an ELF program segment into pagetable at virtual address va.
 // va must be page-aligned
 // and the pages from va to va+sz must already be mapped.
 // Returns 0 on success, -1 on failure.

kernel/file.c

@@ -150,8 +150,6 @@ filewrite(struct file *f, uint64 addr, int n)
     // the maximum log transaction size, including
     // i-node, indirect block, allocation blocks,
     // and 2 blocks of slop for non-aligned writes.
-    // this really belongs lower down, since writei()
-    // might be writing a device like the console.
     int max = ((MAXOPBLOCKS-1-1-2) / 2) * BSIZE;
     int i = 0;
     while(i < n){