minix/kernel/arch/i386/system.c
Ben Gras cd8b915ed9 Primary goal for these changes is:
- no longer have kernel have its own page table that is loaded
    on every kernel entry (trap, interrupt, exception). the primary
    purpose is to reduce the number of required reloads.
Result:
  - kernel can only access memory of process that was running when
    kernel was entered
  - kernel must be mapped into every process page table, so traps to
    kernel keep working
Problem:
  - kernel must often access memory of arbitrary processes (e.g. send
    arbitrary processes messages); this can't happen directly any more;
    usually because that process' page table isn't loaded at all, sometimes
    because that memory isn't mapped in at all, sometimes because it isn't
    mapped in read-write.
So:
  - kernel must be able to map in memory of any process, in its own
    address space.
Implementation:
  - VM and kernel share a range of memory in which addresses of
    all page tables of all processes are available. This has two purposes:
      . Kernel has to know what data to copy in order to map in a range
      . Kernel has to know where to write the data in order to map it in
    That last point is because kernel has to write in the currently loaded
    page table.
  - Processes and kernel are separated through segments; kernel segments
    haven't changed.
  - The kernel keeps the process whose page table is currently loaded
    in 'ptproc.'
  - If it wants to map in a range of memory, it writes the value of the
    page directory entry for that range into the page directory entry
    in the currently loaded map. There is a slot reserved for such
    purposes. The kernel can then access this memory directly.
  - In order to do this, its segment has been increased (and the
    segments of processes start where it ends).
  - In the pagefault handler, detect if the kernel is doing
    'trappable' memory access (i.e. a pagefault isn't a fatal
     error) and if so,
       - set the saved instruction pointer to phys_copy_fault,
	 breaking out of phys_copy
       - set the saved eax register to the address of the page
	 fault, both for sanity checking and for checking in
	 which of the two ranges that phys_copy was called
	 with the fault occured
  - Some boot-time processes do not have their own page table,
    and are mapped in with the kernel, and separated with
    segments. The kernel detects this using HASPT. If such a
    process has to be scheduled, any page table will work and
    no page table switch is done.

Major changes in kernel are
  - When accessing user processes memory, kernel no longer
    explicitly checks before it does so if that memory is OK.
    It simply makes the mapping (if necessary), tries to do the
    operation, and traps the pagefault if that memory isn't present;
    if that happens, the copy function returns EFAULT.
    So all of the CHECKRANGE_OR_SUSPEND macros are gone.
  - Kernel no longer has to copy/read and parse page tables.
  - A message copying optimisation: when messages are copied, and
    the recipient isn't mapped in, they are copied into a buffer
    in the kernel. This is done in QueueMess. The next time
    the recipient is scheduled, this message is copied into
    its memory. This happens in schedcheck().
    This eliminates the mapping/copying step for messages, and makes
    it easier to deliver messages. This eliminates soft_notify.
  - Kernel no longer creates a page table at all, so the vm_setbuf
    and pagetable writing in memory.c is gone.

Minor changes in kernel are
  - ipc_stats thrown out, wasn't used
  - misc flags all renamed to MF_*
  - NOREC_* macros to enter and leave functions that should not
    be called recursively; just sanity checks really
  - code to fully decode segment selectors and descriptors
    to print on exceptions
  - lots of vmassert()s added, only executed if DEBUG_VMASSERT is 1
2009-09-21 14:31:52 +00:00

355 lines
7.2 KiB
C

/* system dependent functions for use inside the whole kernel. */
#include "../../kernel.h"
#include <unistd.h>
#include <ctype.h>
#include <string.h>
#include <ibm/cmos.h>
#include <ibm/bios.h>
#include <minix/portio.h>
#include <minix/u64.h>
#include <minix/sysutil.h>
#include <a.out.h>
#include "proto.h"
#include "../../proc.h"
#include "../../debug.h"
#define CR0_EM 0x0004 /* set to enable trap on any FP instruction */
FORWARD _PROTOTYPE( void ser_debug, (int c));
PUBLIC void arch_shutdown(int how)
{
/* Mask all interrupts, including the clock. */
outb( INT_CTLMASK, ~0);
if(how != RBT_RESET) {
/* return to boot monitor */
outb( INT_CTLMASK, 0);
outb( INT2_CTLMASK, 0);
/* Return to the boot monitor. Set
* the program if not already done.
*/
if (how != RBT_MONITOR)
arch_set_params("", 1);
if(minix_panicing) {
int source, dest;
static char mybuffer[sizeof(params_buffer)];
char *lead = "echo \\n*** kernel messages:\\n";
int leadlen = strlen(lead);
strcpy(mybuffer, lead);
#define DECSOURCE source = (source - 1 + _KMESS_BUF_SIZE) % _KMESS_BUF_SIZE
dest = sizeof(mybuffer)-1;
mybuffer[dest--] = '\0';
source = kmess.km_next;
DECSOURCE;
while(dest >= leadlen) {
char c = kmess.km_buf[source];
if(c == '\n') {
mybuffer[dest--] = 'n';
mybuffer[dest] = '\\';
} else if(isprint(c) &&
c != '\'' && c != '"' &&
c != '\\' && c != ';') {
mybuffer[dest] = c;
} else mybuffer[dest] = ' ';
DECSOURCE;
dest--;
}
arch_set_params(mybuffer, strlen(mybuffer)+1);
}
level0(monitor);
} else {
/* Reset the system by forcing a processor shutdown. First stop
* the BIOS memory test by setting a soft reset flag.
*/
u16_t magic = STOP_MEM_CHECK;
phys_copy(vir2phys(&magic), SOFT_RESET_FLAG_ADDR,
SOFT_RESET_FLAG_SIZE);
level0(reset);
}
}
/* address of a.out headers, set in mpx386.s */
phys_bytes aout;
PUBLIC void arch_get_aout_headers(int i, struct exec *h)
{
/* The bootstrap loader created an array of the a.out headers at
* absolute address 'aout'. Get one element to h.
*/
phys_copy(aout + i * A_MINHDR, vir2phys(h), (phys_bytes) A_MINHDR);
}
PUBLIC void arch_init(void)
{
idt_init();
#if 0
/* Set CR0_EM until we get FP context switching */
write_cr0(read_cr0() | CR0_EM);
#endif
}
#define COM1_BASE 0x3F8
#define COM1_THR (COM1_BASE + 0)
#define COM1_RBR (COM1_BASE + 0)
#define COM1_LSR (COM1_BASE + 5)
#define LSR_DR 0x01
#define LSR_THRE 0x20
PUBLIC void ser_putc(char c)
{
int i;
int lsr, thr;
lsr= COM1_LSR;
thr= COM1_THR;
for (i= 0; i<100000; i++)
{
if (inb( lsr) & LSR_THRE)
break;
}
outb( thr, c);
}
/*===========================================================================*
* do_ser_debug *
*===========================================================================*/
PUBLIC void do_ser_debug()
{
u8_t c, lsr;
lsr= inb(COM1_LSR);
if (!(lsr & LSR_DR))
return;
c = inb(COM1_RBR);
ser_debug(c);
}
PRIVATE void ser_dump_queues(void)
{
int q;
for(q = 0; q < NR_SCHED_QUEUES; q++) {
struct proc *p;
if(rdy_head[q])
printf("%2d: ", q);
for(p = rdy_head[q]; p; p = p->p_nextready) {
printf("%s / %d ", p->p_name, p->p_endpoint);
}
printf("\n");
}
}
PRIVATE void ser_dump_segs(void)
{
struct proc *pp;
for (pp= BEG_PROC_ADDR; pp < END_PROC_ADDR; pp++)
{
if (pp->p_rts_flags & SLOT_FREE)
continue;
kprintf("%d: %s ep %d\n", proc_nr(pp), pp->p_name, pp->p_endpoint);
printseg("cs: ", 1, pp, pp->p_reg.cs);
printseg("ds: ", 0, pp, pp->p_reg.ds);
if(pp->p_reg.ss != pp->p_reg.ds) {
printseg("ss: ", 0, pp, pp->p_reg.ss);
}
}
}
PRIVATE void ser_debug(int c)
{
int u = 0;
do_serial_debug++;
/* Disable interrupts so that we get a consistent state. */
if(!intr_disabled()) { lock; u = 1; };
switch(c)
{
case '1':
ser_dump_proc();
break;
case '2':
ser_dump_queues();
break;
case '3':
ser_dump_segs();
break;
#if DEBUG_TRACE
#define TOGGLECASE(ch, flag) \
case ch: { \
if(verboseflags & flag) { \
verboseflags &= ~flag; \
printf("%s disabled\n", #flag); \
} else { \
verboseflags |= flag; \
printf("%s enabled\n", #flag); \
} \
break; \
}
TOGGLECASE('8', VF_SCHEDULING)
TOGGLECASE('9', VF_PICKPROC)
#endif
}
do_serial_debug--;
if(u) { unlock; }
}
PRIVATE void printslot(struct proc *pp, int level)
{
struct proc *depproc = NULL;
int dep = NONE;
#define COL { int i; for(i = 0; i < level; i++) printf("> "); }
if(level >= NR_PROCS) {
kprintf("loop??\n");
return;
}
COL
kprintf("%d: %s %d prio %d/%d time %d/%d cr3 0x%lx rts %s misc %s",
proc_nr(pp), pp->p_name, pp->p_endpoint,
pp->p_priority, pp->p_max_priority, pp->p_user_time,
pp->p_sys_time, pp->p_seg.p_cr3,
rtsflagstr(pp->p_rts_flags), miscflagstr(pp->p_misc_flags));
if(pp->p_rts_flags & SENDING) {
dep = pp->p_sendto_e;
kprintf(" to: ");
} else if(pp->p_rts_flags & RECEIVING) {
dep = pp->p_getfrom_e;
kprintf(" from: ");
}
if(dep != NONE) {
if(dep == ANY) {
kprintf(" ANY\n");
} else {
int procno;
if(!isokendpt(dep, &procno)) {
kprintf(" ??? %d\n", dep);
} else {
depproc = proc_addr(procno);
if(depproc->p_rts_flags & SLOT_FREE) {
kprintf(" empty slot %d???\n", procno);
depproc = NULL;
} else {
kprintf(" %s\n", depproc->p_name);
}
}
}
} else {
kprintf("\n");
}
COL
proc_stacktrace(pp);
if(depproc)
printslot(depproc, level+1);
}
PUBLIC void ser_dump_proc()
{
struct proc *pp;
for (pp= BEG_PROC_ADDR; pp < END_PROC_ADDR; pp++)
{
if (pp->p_rts_flags & SLOT_FREE)
continue;
printslot(pp, 0);
}
}
#if SPROFILE
PUBLIC int arch_init_profile_clock(u32_t freq)
{
int r;
/* Set CMOS timer frequency. */
outb(RTC_INDEX, RTC_REG_A);
outb(RTC_IO, RTC_A_DV_OK | freq);
/* Enable CMOS timer interrupts. */
outb(RTC_INDEX, RTC_REG_B);
r = inb(RTC_IO);
outb(RTC_INDEX, RTC_REG_B);
outb(RTC_IO, r | RTC_B_PIE);
/* Mandatory read of CMOS register to enable timer interrupts. */
outb(RTC_INDEX, RTC_REG_C);
inb(RTC_IO);
return CMOS_CLOCK_IRQ;
}
PUBLIC void arch_stop_profile_clock(void)
{
int r;
/* Disable CMOS timer interrupts. */
outb(RTC_INDEX, RTC_REG_B);
r = inb(RTC_IO);
outb(RTC_INDEX, RTC_REG_B);
outb(RTC_IO, r & ~RTC_B_PIE);
}
PUBLIC void arch_ack_profile_clock(void)
{
/* Mandatory read of CMOS register to re-enable timer interrupts. */
outb(RTC_INDEX, RTC_REG_C);
inb(RTC_IO);
}
#endif
#define COLOR_BASE 0xB8000L
PUBLIC void cons_setc(int pos, int c)
{
char ch;
ch= c;
phys_copy(vir2phys((vir_bytes)&ch), COLOR_BASE+(20*80+pos)*2, 1);
}
PUBLIC void cons_seth(int pos, int n)
{
n &= 0xf;
if (n < 10)
cons_setc(pos, '0'+n);
else
cons_setc(pos, 'A'+(n-10));
}
/* Saved by mpx386.s into these variables. */
u32_t params_size, params_offset, mon_ds;
PUBLIC int arch_get_params(char *params, int maxsize)
{
phys_copy(seg2phys(mon_ds) + params_offset, vir2phys(params),
MIN(maxsize, params_size));
params[maxsize-1] = '\0';
return OK;
}
PUBLIC int arch_set_params(char *params, int size)
{
if(size > params_size)
return E2BIG;
phys_copy(vir2phys(params), seg2phys(mon_ds) + params_offset, size);
return OK;
}