commit 8148b6ee535b85e97f3b5f3a850b70fdfbbcaf2d
parent 664324745e2257289f7a61e43892ce6e8b8ed9b7
Author: rtm <rtm>
Date: Wed, 12 Jul 2006 11:15:38 +0000
i think my cmpxchg use was wrong in acquire
nesting cli/sti: release shouldn't always enable interrupts
separate setup of lapic from starting of other cpus, so cpu() works earlier
flag to disable locking in console output
make locks work even when curproc==0
(still crashes in clock interrupt)
Diffstat:
11 files changed, 85 insertions(+), 32 deletions(-)
diff --git a/Notes b/Notes
@@ -125,6 +125,10 @@ in general, the table locks protect both free-ness and
why can't i get a lock in console code?
always triple fault
+ because release turns on interrupts!
+ a bad idea very early in main()
+ but mp_init() calls cprintf
+
lock code shouldn't call cprintf...
ide_init doesn't work now?
and IOAPIC: read from unsupported address
diff --git a/console.c b/console.c
@@ -4,6 +4,7 @@
#include "spinlock.h"
struct spinlock console_lock;
+int use_printf_lock = 0;
/*
* copy console output to parallel port, which you can tell
@@ -29,7 +30,8 @@ cons_putc(int c)
unsigned short *crt = (unsigned short *) 0xB8000; // base of CGA memory
int ind;
- //acquire(&console_lock);
+ if(use_printf_lock)
+ acquire(&console_lock);
lpt_putc(c);
@@ -62,7 +64,8 @@ cons_putc(int c)
outb(crtport, 15);
outb(crtport + 1, ind);
- //release(&console_lock);
+ if(use_printf_lock)
+ release(&console_lock);
}
void
@@ -127,6 +130,8 @@ cprintf(char *fmt, ...)
void
panic(char *s)
{
+ use_printf_lock = 0;
+ cprintf("panic: ");
cprintf(s, 0);
cprintf("\n", 0);
while(1)
diff --git a/defs.h b/defs.h
@@ -19,6 +19,8 @@ void wakeup(void *);
void scheduler(void);
void proc_exit(void);
void yield(void);
+void cli(void);
+void sti(void);
// swtch.S
struct jmpbuf;
@@ -46,6 +48,7 @@ void pic_init(void);
// mp.c
void mp_init(void);
+void mp_startthem(void);
int cpu(void);
int mp_isbcpu(void);
void lapic_init(int);
diff --git a/kalloc.c b/kalloc.c
@@ -10,6 +10,9 @@
#include "param.h"
#include "types.h"
#include "defs.h"
+#include "param.h"
+#include "mmu.h"
+#include "proc.h"
#include "spinlock.h"
struct spinlock kalloc_lock;
diff --git a/main.c b/main.c
@@ -8,6 +8,7 @@
#include "syscall.h"
#include "elf.h"
#include "param.h"
+#include "spinlock.h"
extern char edata[], end[];
extern int acpu;
@@ -15,23 +16,33 @@ extern char _binary_user1_start[], _binary_user1_size[];
extern char _binary_usertests_start[], _binary_usertests_size[];
extern char _binary_userfs_start[], _binary_userfs_size[];
+extern use_printf_lock;
+
int
main()
{
struct proc *p;
if (acpu) {
+ cpus[cpu()].clis = 1;
cprintf("an application processor\n");
idtinit(); // CPU's idt
lapic_init(cpu());
lapic_timerinit();
lapic_enableintr();
+ sti();
scheduler();
}
acpu = 1;
+
// clear BSS
memset(edata, 0, end - edata);
+ mp_init(); // just set up apic so cpu() works
+ use_printf_lock = 1;
+
+ cpus[cpu()].clis = 1; // cpu starts as if we had called cli()
+
cprintf("\nxV6\n\n");
pic_init(); // initialize PIC
@@ -56,7 +67,7 @@ main()
p->ppid = 0;
setupsegs(p);
- mp_init(); // multiprocessor
+ mp_startthem();
// turn on timer and enable interrupts on the local APIC
lapic_timerinit();
diff --git a/mp.c b/mp.c
@@ -325,8 +325,6 @@ mp_init()
struct MPCTB *mpctb;
struct MPPE *proc;
struct MPBE *bus;
- int c;
- extern int main();
int i;
ncpu = 0;
@@ -386,13 +384,20 @@ mp_init()
lapic_init(bcpu-cpus);
cprintf("ncpu: %d boot %d\n", ncpu, bcpu-cpus);
+}
+void
+mp_startthem()
+{
extern uint8_t _binary_bootother_start[], _binary_bootother_size[];
+ extern int main();
+ int c;
+
memmove((void *) APBOOTCODE,_binary_bootother_start,
(uint32_t) _binary_bootother_size);
for(c = 0; c < ncpu; c++){
- if (cpus+c == bcpu) continue;
+ if (c == cpu()) continue;
cprintf ("starting processor %d\n", c);
*(unsigned *)(APBOOTCODE-4) = (unsigned) (cpus[c].mpstack) + MPSTACK; // tell it what to use for %esp
*(unsigned *)(APBOOTCODE-8) = (unsigned)&main; // tell it where to jump to
diff --git a/proc.c b/proc.c
@@ -148,6 +148,7 @@ scheduler(void)
if(i < NPROC){
np->state = RUNNING;
+ release(&proc_table_lock);
break;
}
@@ -157,8 +158,6 @@ scheduler(void)
cpus[cpu()].lastproc = np;
curproc[cpu()] = np;
-
- release(&proc_table_lock);
// h/w sets busy bit in TSS descriptor sometimes, and faults
// if it's set in LTR. so clear tss descriptor busy bit.
@@ -252,3 +251,25 @@ proc_exit()
// switch into scheduler
swtch(ZOMBIE);
}
+
+// disable interrupts
+void
+cli(void)
+{
+ cpus[cpu()].clis += 1;
+ if(cpus[cpu()].clis == 1)
+ __asm __volatile("cli");
+}
+
+// enable interrupts
+void
+sti(void)
+{
+ if(cpus[cpu()].clis < 1){
+ cprintf("cpu %d clis %d\n", cpu(), cpus[cpu()].clis);
+ panic("sti");
+ }
+ cpus[cpu()].clis -= 1;
+ if(cpus[cpu()].clis < 1)
+ __asm __volatile("sti");
+}
diff --git a/proc.h b/proc.h
@@ -69,6 +69,7 @@ struct cpu {
struct jmpbuf jmpbuf;
char mpstack[MPSTACK]; // per-cpu start-up stack, only used to get into main()
struct proc *lastproc; // last proc scheduled on this cpu (never NULL)
+ int clis; // cli() nesting depth
};
extern struct cpu cpus[NCPU];
diff --git a/spinlock.c b/spinlock.c
@@ -8,6 +8,8 @@
#define DEBUG 0
+extern use_printf_lock;
+
int getcallerpc(void *v) {
return ((int*)v)[-1];
}
@@ -15,37 +17,49 @@ int getcallerpc(void *v) {
void
acquire(struct spinlock * lock)
{
- struct proc * cp = curproc[cpu()];
+ unsigned who;
+
+ if(curproc[cpu()])
+ who = (unsigned) curproc[cpu()];
+ else
+ who = cpu() + 1;
- // on a real machine there would be a memory barrier here
if(DEBUG) cprintf("cpu%d: acquiring at %x\n", cpu(), getcallerpc(&lock));
- if (cp && lock->p == cp && lock->locked){
+
+ if (lock->who == who && lock->locked){
lock->count += 1;
} else {
cli();
- while ( cmpxchg(0, 1, &lock->locked) != 1 ) { ; }
+ // if we get the lock, eax will be zero
+ // if we don't get the lock, eax will be one
+ while ( cmpxchg(0, 1, &lock->locked) == 1 ) { ; }
lock->locker_pc = getcallerpc(&lock);
lock->count = 1;
- lock->p = cp;
+ lock->who = who;
}
+
if(DEBUG) cprintf("cpu%d: acquired at %x\n", cpu(), getcallerpc(&lock));
}
void
release(struct spinlock * lock)
{
- struct proc * cp = curproc[cpu()];
+ unsigned who;
+
+ if(curproc[cpu()])
+ who = (unsigned) curproc[cpu()];
+ else
+ who = cpu() + 1;
if(DEBUG) cprintf ("cpu%d: releasing at %x\n", cpu(), getcallerpc(&lock));
- if(lock->p != cp || lock->count < 1 || lock->locked != 1)
+ if(lock->who != who || lock->count < 1 || lock->locked != 1)
panic("release");
lock->count -= 1;
if(lock->count < 1){
- lock->p = 0;
+ lock->who = 0;
cmpxchg(1, 0, &lock->locked);
sti();
- // on a real machine there would be a memory barrier here
}
}
diff --git a/spinlock.h b/spinlock.h
@@ -1,6 +1,6 @@
struct spinlock {
unsigned int locked;
- struct proc *p;
+ unsigned who;
int count;
unsigned locker_pc;
};
diff --git a/x86.h b/x86.h
@@ -304,20 +304,6 @@ read_tsc(void)
return tsc;
}
-// disable interrupts
-static __inline void
-cli(void)
-{
- __asm __volatile("cli");
-}
-
-// enable interrupts
-static __inline void
-sti(void)
-{
- __asm __volatile("sti");
-}
-
struct PushRegs {
/* registers as pushed by pusha */
uint32_t reg_edi;
