1991/0711/pc/mmu.c (diff list | history)

pc/mmu.c on 1991/0612
1991/0612		#include "u.h" #include "lib.h" #include "mem.h" #include "dat.h" #include "fns.h" #include "io.h"
1991/0613		/*
1991/0625		* task state segment. Plan 9 ignores all the task switching goo and just * uses the tss for esp0 and ss0 on gate's into the kernel, interrupts, * and exceptions. The rest is completely ignored. * * This means that we only need one tss in the whole system. */ typedef struct Tss Tss; struct Tss { ulong backlink; /* unused */ ulong esp0; /* pl0 stack pointer */ ulong ss0; /* pl0 stack selector */ ulong esp1; /* pl1 stack pointer */ ulong ss1; /* pl1 stack selector */ ulong esp2; /* pl2 stack pointer */ ulong ss2; /* pl2 stack selector */ ulong cr3; /* page table descriptor */ ulong eip; /* instruction pointer */ ulong eflags; /* processor flags */ ulong eax; /* general (hah?) registers */ ulong ecx; ulong edx; ulong ebx; ulong esp; ulong ebp; ulong esi; ulong edi; ulong es; /* segment selectors */ ulong cs; ulong ss; ulong ds; ulong fs; ulong gs; ulong ldt; /* local descriptor table */ ulong iomap; /* io map base */ }; /*
1991/0703		* segment descriptor initializers */ #define DATASEG(p) { 0xFFFF, SEGG|SEGB|(0xF<<16)|SEGP|SEGPL(p)|SEGDATA|SEGW } #define EXECSEG(p) { 0xFFFF, SEGG|SEGD|(0xF<<16)|SEGP|SEGPL(p)|SEGEXEC|SEGR } #define CALLGATE(s,o,p) { (o)&0xFFFF|((s)<<16), (o)&0xFFFF0000|SEGP|SEGPL(p)|SEGCG }
1991/0706		#define D16SEG(p) { 0xFFFF, (0x0<<16)|SEGP|SEGPL(p)|SEGDATA|SEGW } #define E16SEG(p) { 0xFFFF, (0x0<<16)|SEGP|SEGPL(p)|SEGEXEC|SEGR }
1991/0703		/*
1991/0613		* global descriptor table describing all segments */
1991/0706		Segdesc gdt[] =
1991/0612		{
1991/0613		[NULLSEG] { 0, 0}, /* null descriptor */ [KDSEG] DATASEG(0), /* kernel data/stack */
1991/0703		[KESEG] EXECSEG(0), /* kernel code */
1991/0613		[UDSEG] DATASEG(3), /* user data/stack */
1991/0703		[UESEG] EXECSEG(3), /* user code */ [SYSGATE] CALLGATE(KESEL,0,3), /* call gate for system calls */
1991/0706		[RDSEG] D16SEG(0), /* reboot data/stack */ [RESEG] E16SEG(0), /* reboot code */
1991/0613		};
1991/0703
1991/0711		extern ulong tpt[];
1991/0703		void mmuinit(void) {
1991/0711
1991/0703		gdt[SYSGATE].d0 = ((ulong)systrap)&0xFFFF|(KESEL<<16); gdt[SYSGATE].d1 = ((ulong)systrap)&0xFFFF0000|SEGP|SEGPL(3)|SEGCG; lgdt(gdt, sizeof gdt);
1991/0711		} void mapstack(Proc *p) { } void flushmmu(void) { } void mmurelease(Proc *p) { } void putmmu(ulong x, ulong y, Page*z) { } void invalidateu(void) {
1991/0703		} void systrap(void) { panic("system trap from user"); }