diff options
| -rw-r--r-- | defs.h | 2 | ||||
| -rw-r--r-- | proc.c | 8 | ||||
| -rw-r--r-- | proc.h | 26 | ||||
| -rw-r--r-- | swtch.S | 36 |
4 files changed, 31 insertions, 41 deletions
@@ -107,7 +107,7 @@ void wakeup(void*); void yield(void); // swtch.S -void swtch(struct context*, struct context*); +void swtch(struct context**, struct context**); // spinlock.c void acquire(struct spinlock*); @@ -137,9 +137,9 @@ copyproc(struct proc *p) } // Set up new context to start executing at forkret (see below). - memset(&np->context, 0, sizeof(np->context)); - np->context.eip = (uint)forkret; - np->context.esp = (uint)np->tf; + np->context = (struct context *)np->tf - 1; + memset(np->context, 0, sizeof(*np->context)); + np->context->eip = (uint)forkret; // Clear %eax so that fork system call returns 0 in child. np->tf->eax = 0; @@ -477,7 +477,7 @@ procdump(void) state = "???"; cprintf("%d %s %s", p->pid, state, p->name); if(p->state == SLEEPING){ - getcallerpcs((uint*)p->context.ebp+2, pc); + getcallerpcs((uint*)p->context->ebp+2, pc); for(j=0; j<10 && pc[j] != 0; j++) cprintf(" %p", pc[j]); } @@ -7,21 +7,17 @@ #define NSEGS 6 // Saved registers for kernel context switches. -// Don't need to save all the %fs etc. segment registers, +// Don't need to save all the segment registers (%cs, etc), // because they are constant across kernel contexts. -// Save all the regular registers so we don't need to care -// which are caller save, but not the return register %eax. -// (Not saving %eax just simplifies the switching code.) +// Stack pointer is encoded in the address of context, +// which must be placed at the bottom of the stack. // The layout of context must match code in swtch.S. struct context { - int eip; - int esp; - int ebx; - int ecx; - int edx; - int esi; - int edi; - int ebp; + uint edi; + uint esi; + uint ebx; + uint ebp; + uint eip; }; enum proc_state { UNUSED, EMBRYO, SLEEPING, RUNNABLE, RUNNING, ZOMBIE }; @@ -38,8 +34,8 @@ struct proc { int killed; // If non-zero, have been killed struct file *ofile[NOFILE]; // Open files struct inode *cwd; // Current directory - struct context context; // Switch here to run process - struct trapframe *tf; // Trap frame for current interrupt + struct context *context; // Switch here to run process + struct trapframe *tf; // Trap frame for current syscall char name[16]; // Process name (debugging) }; @@ -53,7 +49,7 @@ struct proc { struct cpu { uchar apicid; // Local APIC ID struct proc *curproc; // Process currently running. - struct context context; // Switch here to enter scheduler + struct context *context; // Switch here to enter scheduler struct taskstate ts; // Used by x86 to find stack for interrupt struct segdesc gdt[NSEGS]; // x86 global descriptor table volatile uint booted; // Has the CPU started? @@ -1,32 +1,26 @@ -# void swtch(struct context *old, struct context *new); +# void swtch(struct context **old, struct context **new); # # Save current register context in old # and then load register context from new. .globl swtch swtch: - # Save old registers movl 4(%esp), %eax + movl 8(%esp), %edx - popl 0(%eax) # %eip - movl %esp, 4(%eax) - movl %ebx, 8(%eax) - movl %ecx, 12(%eax) - movl %edx, 16(%eax) - movl %esi, 20(%eax) - movl %edi, 24(%eax) - movl %ebp, 28(%eax) + # Save old callee-save registers + pushl %ebp + pushl %ebx + pushl %esi + pushl %edi - # Load new registers - movl 4(%esp), %eax # not 8(%esp) - popped return address above - - movl 28(%eax), %ebp - movl 24(%eax), %edi - movl 20(%eax), %esi - movl 16(%eax), %edx - movl 12(%eax), %ecx - movl 8(%eax), %ebx - movl 4(%eax), %esp - pushl 0(%eax) # %eip + # Switch stacks + movl %esp, (%eax) + movl (%edx), %esp + # Load new callee-save registers + popl %edi + popl %esi + popl %ebx + popl %ebp ret |