74 lines
2.7 KiB
C
74 lines
2.7 KiB
C
// Segments in proc->gdt.
|
|
// Also known to bootasm.S and trapasm.S
|
|
#define SEG_KCODE 1 // kernel code
|
|
#define SEG_KDATA 2 // kernel data+stack
|
|
#define SEG_KCPU 3 // kernel per-cpu data
|
|
#define SEG_UCODE 4
|
|
#define SEG_UDATA 5
|
|
#define SEG_TSS 6 // this process's task state
|
|
#define NSEGS 7
|
|
|
|
// Saved registers for kernel context switches.
|
|
// Don't need to save all the segment registers (%cs, etc),
|
|
// because they are constant across kernel contexts.
|
|
// Don't need to save %eax, %ecx, %edx, because the
|
|
// x86 convention is that the caller has saved them.
|
|
// Contexts are stored at the bottom of the stack they
|
|
// describe; the stack pointer is the address of the context.
|
|
// The layout of the context must match the code in swtch.S.
|
|
struct context {
|
|
uint edi;
|
|
uint esi;
|
|
uint ebx;
|
|
uint ebp;
|
|
uint eip;
|
|
};
|
|
|
|
enum proc_state { UNUSED, EMBRYO, SLEEPING, RUNNABLE, RUNNING, ZOMBIE };
|
|
|
|
// Per-process state
|
|
struct proc {
|
|
char *mem; // Start of process memory (kernel address)
|
|
uint sz; // Size of process memory (bytes)
|
|
char *kstack; // Bottom of kernel stack for this process
|
|
enum proc_state state; // Process state
|
|
volatile int pid; // Process ID
|
|
struct proc *parent; // Parent process
|
|
struct trapframe *tf; // Trap frame for current syscall
|
|
struct context *context; // Switch here to run process
|
|
void *chan; // If non-zero, sleeping on chan
|
|
int killed; // If non-zero, have been killed
|
|
struct file *ofile[NOFILE]; // Open files
|
|
struct inode *cwd; // Current directory
|
|
char name[16]; // Process name (debugging)
|
|
};
|
|
|
|
// Process memory is laid out contiguously, low addresses first:
|
|
// text
|
|
// original data and bss
|
|
// fixed-size stack
|
|
// expandable heap
|
|
|
|
// Per-CPU state
|
|
struct cpu {
|
|
uchar apicid; // Local APIC ID
|
|
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?
|
|
int ncli; // Depth of pushcli nesting.
|
|
int intena; // Were interrupts enabled before pushcli?
|
|
void *tls[2];
|
|
};
|
|
|
|
extern struct cpu cpus[NCPU];
|
|
extern int ncpu;
|
|
|
|
// Per-CPU variables, holding pointers to the
|
|
// current cpu and to the current process.
|
|
// The __thread prefix tells gcc to refer to them in the segment
|
|
// pointed at by gs; the name __thread derives from the use
|
|
// of the same mechanism to provide per-thread storage in
|
|
// multithreaded user programs.
|
|
extern __thread struct cpu *c; // This cpu.
|
|
extern __thread struct proc *cp; // Current process on this cpu.
|