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minix/kernel/system.c
Jorrit Herder 7279bb68ef Applied MINIX 2.0.4 pathes provides by Al Woodhull.
2005-06-17 13:00:04 +00:00

536 lines
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/* This task handles the interface between the kernel and user-level servers.
* System services can be accessed by doing a system call. System calls are
* transformed into request messages, which are handled by this task. By
* convention, a sys_call() is transformed in a SYS_CALL request message that
* is handled in a function named do_call().
*
* A private call vector is used to map all system calls to the functions that
* handle them. The actual handler functions are contained in separate files
* to keep this file clean. The call vector is used in the system task's main
* loop to handle all incoming requests.
*
* In addition to the main sys_task() entry point, which starts the main loop,
* there are several other minor entry points:
* cause_sig: take action to cause a signal to occur
* clear_proc: clean up a process in the process table, e.g. on exit
* umap_local: map virtual address in LOCAL_SEG to physical
* umap_remote: map virtual address in REMOTE_SEG to physical
* umap_bios: map virtual address in BIOS_SEG to physical
* numap_local: umap_local D segment from proc nr instead of pointer
* virtual_copy: copy bytes from one virtual address to another
* get_randomness: accumulate randomness in a buffer
* generic_handler: interrupt handler for user-level device drivers
*
* Changes:
* Apr 25, 2005 made mapping of call vector explicit (Jorrit N. Herder)
* Oct 29, 2004 new clear_proc() function (Jorrit N. Herder)
* Oct 17, 2004 generic handler and IRQ policies (Jorrit N. Herder)
* Oct 10, 2004 dispatch system calls from call vector (Jorrit N. Herder)
* Sep 30, 2004 source code documentation updated (Jorrit N. Herder)
* Sep 10, 2004 system call functions in library (Jorrit N. Herder)
* 2004 to 2005 various new syscalls (see syslib.h) (Jorrit N. Herder)
*/
#include "kernel.h"
#include "system.h"
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>
#include <sys/sigcontext.h>
#include <sys/svrctl.h>
#include <minix/callnr.h>
#include "sendmask.h"
#if (CHIP == INTEL)
#include <ibm/memory.h>
#include "protect.h"
#endif
/* Declaration of the call vector that defines the mapping of system calls
* to handler functions. The vector is initialized in sys_init() with map(),
* which makes sure the system call numbers are ok. No space is allocated,
* because the dummy is declared extern. If an illegal call is given, the
* array size will be negative and this won't compile.
*/
PUBLIC int (*call_vec[NR_SYS_CALLS])(message *m_ptr);
#define map(call_nr, handler) \
{extern int dummy[NR_SYS_CALLS > (unsigned) (call_nr) ? 1 : -1];} \
call_vec[(call_nr)] = (handler)
FORWARD _PROTOTYPE( void initialize, (void));
/*===========================================================================*
* sys_task *
*===========================================================================*/
PUBLIC void sys_task()
{
/* Main entry point of sys_task. Get the message and dispatch on type. */
static message m;
register int result, debug;
/* Initialize the system task. */
initialize();
while (TRUE) {
/* Get work. */
receive(ANY, &m);
/* Handle the request. */
if ((unsigned) m.m_type < NR_SYS_CALLS) {
result = (*call_vec[m.m_type])(&m); /* do system call */
} else {
kprintf("Warning, illegal SYSTASK request from %d.\n", m.m_source);
result = EBADREQUEST; /* illegal message type */
}
/* Send a reply, unless inhibited by a handler function. Use the kernel
* function lock_send() to prevent a system call trap. The destination
* is known to be blocked waiting for a message.
*/
if (result != EDONTREPLY) {
debug = m.m_type;
m.m_type = result; /* report status of call */
if (OK != lock_send(m.m_source, &m)) {
kprintf("Warning, SYSTASK couldn't reply to request %d", debug);
kprintf(" from %d\n", m.m_source);
}
}
}
}
/*===========================================================================*
* initialize *
*===========================================================================*/
PRIVATE void initialize(void)
{
register struct proc *rp;
int i;
/* Initialize IRQ handler hooks. Mark all hooks available. */
for (i=0; i<NR_IRQ_HOOKS; i++) {
irq_hooks[i].proc_nr = NONE;
}
/* Initialize all alarm timers for all processes. */
for (rp=BEG_PROC_ADDR; rp < END_PROC_ADDR; rp++) {
tmr_inittimer(&(rp->p_alarm_timer));
}
/* Initialize the call vector to a safe default handler. Some system calls
* may be disabled or nonexistant. Then explicitely map known calls to their
* handler functions. This is done with a macro that gives a compile error
* if an illegal call number is used. The ordering is not important here.
*/
for (i=0; i<NR_SYS_CALLS; i++) {
call_vec[i] = do_unused;
}
/* Process management. */
map(SYS_FORK, do_fork); /* informs kernel that a process has forked */
map(SYS_XIT, do_xit); /* informs kernel that a process has exited */
map(SYS_NEWMAP, do_newmap); /* allows PM to set up a process memory map */
map(SYS_EXEC, do_exec); /* sets program counter and stack pointer after EXEC */
map(SYS_TRACE, do_trace); /* request a trace operation */
/* Signal handling. */
map(SYS_KILL, do_kill); /* cause a process to be signaled */
map(SYS_GETSIG, do_getsig); /* PM checks for pending signals */
map(SYS_ENDSIG, do_endsig); /* PM finished processing signal */
map(SYS_SIGSEND, do_sigsend); /* start POSIX-style signal */
map(SYS_SIGRETURN, do_sigreturn); /* return from POSIX-style signal */
/* Clock functionality. */
map(SYS_TIMES, do_times); /* get uptime and process times */
map(SYS_SIGNALRM, do_signalrm); /* causes an alarm signal */
map(SYS_SYNCALRM, do_syncalrm); /* send a notification message */
/* Device I/O. */
map(SYS_IRQCTL, do_irqctl); /* interrupt control operations */
map(SYS_DEVIO, do_devio); /* inb, inw, inl, outb, outw, outl */
map(SYS_SDEVIO, do_sdevio); /* phys_insb, _insw, _outsb, _outsw */
map(SYS_VDEVIO, do_vdevio); /* vector with devio requests */
/* Server and driver control. */
map(SYS_SEGCTL, do_segctl); /* add segment and get selector */
map(SYS_IOPENABLE, do_iopenable); /* enable CPU I/O protection bits */
map(SYS_SVRCTL, do_svrctl); /* kernel control functions */
map(SYS_EXIT, do_exit); /* exit a system process*/
/* Copying. */
map(SYS_UMAP, do_umap); /* map virtual to physical address */
map(SYS_VIRCOPY, do_vircopy); /* use pure virtual addressing */
map(SYS_PHYSCOPY, do_physcopy); /* use physical addressing */
map(SYS_PHYSZERO, do_physzero); /* zero physical memory region */
map(SYS_VIRVCOPY, do_virvcopy); /* vector with copy requests */
map(SYS_PHYSVCOPY, do_physvcopy); /* vector with copy requests */
/* Miscellaneous. */
map(SYS_ABORT, do_abort); /* abort MINIX */
map(SYS_GETINFO, do_getinfo); /* request system information */
}
/*===========================================================================*
* clear_proc *
*===========================================================================*/
PUBLIC void clear_proc(proc_nr)
int proc_nr; /* slot of process to clean up */
{
register struct proc *rp, *rc;
#if DEAD_CODE
struct proc *np, *xp;
#else
register struct proc **xpp; /* iterate over caller queue */
#endif
int i;
/* Get a pointer to the process that exited. */
rc = proc_addr(proc_nr);
/* Turn off any alarm timers at the clock. */
reset_timer(&rc->p_alarm_timer);
/* Make sure the exiting process is no longer scheduled. */
if (rc->p_flags == 0) lock_unready(rc);
/* If the process being terminated happens to be queued trying to send a
* message (e.g., the process was killed by a signal, rather than it doing
* an exit or it is forcibly shutdown in the stop sequence), then it must
* be removed from the message queues.
*/
if (rc->p_flags & SENDING) {
/* Check all proc slots to see if the exiting process is queued. */
for (rp = BEG_PROC_ADDR; rp < END_PROC_ADDR; rp++) {
if (rp->p_caller_q == NIL_PROC) continue;
#if DEAD_CODE
if (rp->p_caller_q == rc) {
/* Exiting process is on front of this queue. */
rp->p_caller_q = rc->p_q_link;
break;
} else {
/* See if exiting process is in middle of queue. */
np = rp->p_caller_q;
while ( ( xp = np->p_q_link) != NIL_PROC) {
if (xp == rc) {
np->p_q_link = xp->p_q_link;
break;
} else {
np = xp;
}
}
}
#else
/* Make sure that the exiting process is not on the queue. */
xpp = &rp->p_caller_q;
while (*xpp != NIL_PROC) { /* check entire queue */
if (*xpp == rc) { /* process is on the queue */
*xpp = (*xpp)->p_q_link; /* replace by next process */
break;
}
xpp = &(*xpp)->p_q_link; /* proceed to next queued */
}
#endif
}
}
/* Check the table with IRQ hooks to see if hooks should be released. */
for (i=0; i < NR_IRQ_HOOKS; i++) {
if (irq_hooks[i].proc_nr == proc_nr)
irq_hooks[i].proc_nr = NONE;
}
/* Check if there are pending notifications. Release the buffers. */
while (rc->p_ntf_q != NULL) {
i = (int) (rc->p_ntf_q - &notify_buffer[0]);
free_bit(i, notify_bitmap, NR_NOTIFY_BUFS);
rc->p_ntf_q = rc->p_ntf_q->n_next;
}
/* Now clean up the process table entry. Reset to defaults. */
kstrncpy(rc->p_name, "<none>", P_NAME_LEN); /* unset name */
sigemptyset(&rc->p_pending); /* remove pending signals */
rc->p_pendcount = 0; /* all signals are gone */
rc->p_flags = 0; /* remove all flags */
rc->p_type = P_NONE; /* announce slot empty */
rc->p_sendmask = DENY_ALL_MASK; /* set most restrictive mask */
#if (CHIP == M68000)
pmmu_delete(rc); /* we're done, remove tables */
#endif
}
/*===========================================================================*
* get_randomness *
*===========================================================================*/
PUBLIC void get_randomness()
{
/* Gather random information with help of the CPU's cycle counter. Only use
* the lowest bytes because the highest bytes won't differ that much.
*/
unsigned long tsc_high;
read_tsc(&tsc_high, &krandom.r_buf[krandom.r_next]);
if (krandom.r_size < RANDOM_ELEMENTS) krandom.r_size ++;
krandom.r_next = (krandom.r_next + 1 ) % RANDOM_ELEMENTS;
}
/*===========================================================================*
* generic_handler *
*===========================================================================*/
PUBLIC int generic_handler(hook)
irq_hook_t *hook;
{
/* This function handles hardware interrupt in a simple and generic way. All
* interrupts are transformed into messages to a driver. The IRQ line will be
* reenabled if the policy says so.
* In addition, the interrupt handler gathers random information in a buffer
* by timestamping the interrupts.
*/
message m;
/* Gather random information. */
get_randomness();
/* Build notification message and return. */
m.NOTIFY_TYPE = HARD_INT;
m.NOTIFY_ARG = hook->irq;
lock_notify(hook->proc_nr, &m);
return(hook->policy & IRQ_REENABLE);
}
/*===========================================================================*
* cause_sig *
*===========================================================================*/
PUBLIC void cause_sig(proc_nr, sig_nr)
int proc_nr; /* process to be signalled */
int sig_nr; /* signal to be sent, 1 to _NSIG */
{
/* A system process wants to send a signal to a process. Examples are:
* TTY wanting to cause SIGINT upon getting a DEL
* CLOCK wanting to cause SIGALRM when timer expires
* FS wanting to cause SIGPIPE for a broken pipe
* Signals are handled by sending a message to PM. This function handles the
* signals and makes sure the PM gets them by sending a notification. The
* process being signaled is blocked while PM has not finished all signals
* for it. These signals are counted in p_pendcount, and the SIG_PENDING
* flag is kept nonzero while there are some. It is not sufficient to ready
* the process when PM is informed, because PM can block waiting for FS to
* do a core dump.
*/
register struct proc *rp, *mmp;
message m;
rp = proc_addr(proc_nr);
if (sigismember(&rp->p_pending, sig_nr))
return; /* this signal already pending */
sigaddset(&rp->p_pending, sig_nr);
++rp->p_pendcount; /* count new signal pending */
if (rp->p_flags & PENDING)
return; /* another signal already pending */
if (rp->p_flags == 0) lock_unready(rp);
rp->p_flags |= PENDING | SIG_PENDING;
m.NOTIFY_TYPE = KSIG_PENDING;
m.NOTIFY_ARG = 0;
m.NOTIFY_FLAGS = 0;
lock_notify(PM_PROC_NR, &m);
}
/*===========================================================================*
* umap_bios *
*===========================================================================*/
PUBLIC phys_bytes umap_bios(rp, vir_addr, bytes)
register struct proc *rp; /* pointer to proc table entry for process */
vir_bytes vir_addr; /* virtual address in BIOS segment */
vir_bytes bytes; /* # of bytes to be copied */
{
/* Calculate the physical memory address at the BIOS. Note: currently, BIOS
* address zero (the first BIOS interrupt vector) is not considered, as an
* error here, but since the physical address will be zero as well, the
* calling function will think an error occurred. This is not a problem,
* since no one uses the first BIOS interrupt vector.
*/
phys_bytes phys_addr;
/* Check all acceptable ranges. */
#if 0
if (vir_addr >= BIOS_MEM_BEGIN && vir_addr + bytes <= BIOS_MEM_END)
return (phys_bytes) vir_addr;
else if (vir_addr >= UPPER_MEM_BEGIN && vir_addr + bytes <= UPPER_MEM_END)
return (phys_bytes) vir_addr;
#else
if (vir_addr >= BIOS_MEM_BEGIN && vir_addr + bytes <= UPPER_MEM_END)
return (phys_bytes) vir_addr;
#endif
kprintf("Warning, error in umap_bios, virtual address 0x%x\n", vir_addr);
return 0;
}
/*===========================================================================*
* umap_local *
*===========================================================================*/
PUBLIC phys_bytes umap_local(rp, seg, vir_addr, bytes)
register struct proc *rp; /* pointer to proc table entry for process */
int seg; /* T, D, or S segment */
vir_bytes vir_addr; /* virtual address in bytes within the seg */
vir_bytes bytes; /* # of bytes to be copied */
{
/* Calculate the physical memory address for a given virtual address. */
vir_clicks vc; /* the virtual address in clicks */
phys_bytes pa; /* intermediate variables as phys_bytes */
#if (CHIP == INTEL)
phys_bytes seg_base;
#endif
/* If 'seg' is D it could really be S and vice versa. T really means T.
* If the virtual address falls in the gap, it causes a problem. On the
* 8088 it is probably a legal stack reference, since "stackfaults" are
* not detected by the hardware. On 8088s, the gap is called S and
* accepted, but on other machines it is called D and rejected.
* The Atari ST behaves like the 8088 in this respect.
*/
if (bytes <= 0) return( (phys_bytes) 0);
if (vir_addr + bytes <= vir_addr) return 0; /* overflow */
vc = (vir_addr + bytes - 1) >> CLICK_SHIFT; /* last click of data */
#if (CHIP == INTEL) || (CHIP == M68000)
if (seg != T)
seg = (vc < rp->p_memmap[D].mem_vir + rp->p_memmap[D].mem_len ? D : S);
#else
if (seg != T)
seg = (vc < rp->p_memmap[S].mem_vir ? D : S);
#endif
if((vir_addr>>CLICK_SHIFT) >= rp->p_memmap[seg].mem_vir +
rp->p_memmap[seg].mem_len) return( (phys_bytes) 0 );
if(vc >= rp->p_memmap[seg].mem_vir +
rp->p_memmap[seg].mem_len) return( (phys_bytes) 0 );
#if (CHIP == INTEL)
seg_base = (phys_bytes) rp->p_memmap[seg].mem_phys;
seg_base = seg_base << CLICK_SHIFT; /* segment origin in bytes */
#endif
pa = (phys_bytes) vir_addr;
#if (CHIP != M68000)
pa -= rp->p_memmap[seg].mem_vir << CLICK_SHIFT;
return(seg_base + pa);
#endif
#if (CHIP == M68000)
pa -= (phys_bytes)rp->p_memmap[seg].mem_vir << CLICK_SHIFT;
pa += (phys_bytes)rp->p_memmap[seg].mem_phys << CLICK_SHIFT;
return(pa);
#endif
}
/*==========================================================================*
* numap_local *
*==========================================================================*/
PUBLIC phys_bytes numap_local(proc_nr, vir_addr, bytes)
int proc_nr; /* process number to be mapped */
vir_bytes vir_addr; /* virtual address in bytes within D seg */
vir_bytes bytes; /* # of bytes required in segment */
{
/* Do umap_local() starting from a process number instead of a pointer.
* This function is used by device drivers, so they need not know about the
* process table. To save time, there is no 'seg' parameter. The segment
* is always D.
*/
return(umap_local(proc_addr(proc_nr), D, vir_addr, bytes));
}
/*===========================================================================*
* umap_remote *
*===========================================================================*/
PUBLIC phys_bytes umap_remote(rp, seg, vir_addr, bytes)
register struct proc *rp; /* pointer to proc table entry for process */
int seg; /* index of remote segment */
vir_bytes vir_addr; /* virtual address in bytes within the seg */
vir_bytes bytes; /* # of bytes to be copied */
{
/* Calculate the physical memory address for a given virtual address. */
struct far_mem *fm;
if (bytes <= 0) return( (phys_bytes) 0);
if (seg < 0 || seg >= NR_REMOTE_SEGS) return( (phys_bytes) 0);
fm = &rp->p_farmem[seg];
if (! fm->in_use) return( (phys_bytes) 0);
if (vir_addr + bytes > fm->mem_len) return( (phys_bytes) 0);
return(fm->mem_phys + (phys_bytes) vir_addr);
}
/*==========================================================================*
* virtual_copy *
*==========================================================================*/
PUBLIC int virtual_copy(src_addr, dst_addr, bytes)
struct vir_addr *src_addr; /* source virtual address */
struct vir_addr *dst_addr; /* destination virtual address */
vir_bytes bytes; /* # of bytes to copy */
{
/* Copy bytes from virtual address src_addr to virtual address dst_addr.
* Virtual addresses can be in ABS, LOCAL_SEG, REMOTE_SEG, or BIOS_SEG.
*/
struct vir_addr *vir_addr[2]; /* virtual source and destination address */
phys_bytes phys_addr[2]; /* absolute source and destination */
int seg_index;
int i;
/* Check copy count. */
if (bytes <= 0) {
kprintf("v_cp: copy count problem <= 0\n", NO_NUM);
return(EDOM);
}
/* Do some more checks and map virtual addresses to physical addresses. */
vir_addr[_SRC_] = src_addr;
vir_addr[_DST_] = dst_addr;
for (i=_SRC_; i<=_DST_; i++) {
/* Get physical address. */
switch((vir_addr[i]->segment & SEGMENT_TYPE)) {
case LOCAL_SEG:
seg_index = vir_addr[i]->segment & SEGMENT_INDEX;
phys_addr[i] = umap_local( proc_addr(vir_addr[i]->proc_nr),
seg_index, vir_addr[i]->offset, bytes );
break;
case REMOTE_SEG:
seg_index = vir_addr[i]->segment & SEGMENT_INDEX;
phys_addr[i] = umap_remote( proc_addr(vir_addr[i]->proc_nr),
seg_index, vir_addr[i]->offset, bytes );
break;
case BIOS_SEG:
phys_addr[i] = umap_bios( proc_addr(vir_addr[i]->proc_nr),
vir_addr[i]->offset, bytes );
break;
case PHYS_SEG:
phys_addr[i] = vir_addr[i]->offset;
break;
default:
kprintf("v_cp: Unknown segment type: %d\n",
vir_addr[i]->segment & SEGMENT_TYPE);
return(EINVAL);
}
/* Check if mapping succeeded. */
if (phys_addr[i] <= 0 && vir_addr[i]->segment != PHYS_SEG) {
kprintf("v_cp: Mapping failed ... phys <= 0\n", NO_NUM);
return(EFAULT);
}
}
/* Now copy bytes between physical addresseses. */
phys_copy(phys_addr[_SRC_], phys_addr[_DST_], (phys_bytes) bytes);
return(OK);
}
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