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minix/kernel/system.c
Ben Gras 9865aeaa79 Initial revision
2005-04-21 14:53:53 +00:00

532 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
* vir_copy: copy bytes from one process to another
* generic_handler: interrupt handler for user-level device drivers
*
* Changes:
* 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)
* 2003/2004 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 "protect.h"
#endif
FORWARD _PROTOTYPE( void initialize, (void));
/* Declaration of the call vector that defines the mapping of system calls to
* handler functions. The order of the do_call handler functions must match
* the SYS_CALL numbering defined in <minix/com.h>.
*/
PUBLIC _PROTOTYPE (int (*call_vec[]), (message *m_ptr) ) = {
do_times, /* 0: get uptime and process CPU time consumption */
do_xit, /* 1: informs kernel that a process has exited */
do_unused, /* 2: unused */
do_sigctl, /* 3: MM signal control (incl. POSIX style handling) */
do_fork, /* 4: informs kernel that a process has forked */
do_newmap, /* 5: allows MM to set up a process memory map */
do_copy, /* 6: copy a block of data between processes */
do_exec, /* 7: sets program counter and stack pointer after EXEC */
do_unused, /* 8: unused */
do_abort, /* 9: MM or FS cannot go on; abort MINIX */
do_kill, /* 10: cause a signal to be sent via MM */
do_umap, /* 11: compute the physical address for a virtual address */
do_unused, /* 12: returns the next free chunk of physical memory */
do_trace, /* 13: request a trace operation */
do_vcopy, /* 14: request a series of data blocks to be copied */
do_signalrm, /* 15: schedule an alarm that causes an alarm signal */
do_syncalrm, /* 16: schedule an alarm that sends a notification message */
do_flagalrm, /* 17: schedule an alarm that sets a timeout flag to 1 */
do_unused, /* 18: unused */
do_svrctl, /* 19: handles miscelleneous kernel control functions */
do_sdevio, /* 20: device I/O: phys_insb, _insw, _outsb, _outsw */
do_unused, /* 21: unused */
do_getinfo, /* 22: request some kind of system information */
do_devio, /* 23: device I/O: inb, inw, inl, outb, outw, outl */
do_vdevio, /* 24: device I/O: vector with in[b|w|l], out[b|w|l] */
do_irqctl, /* 25: request an interrupt control operation */
do_kmalloc, /* 26: request allocation of (DMA) buffer in mem chunk */
do_iopenable, /* 27: allow a user process to use I/O instructions */
do_phys2seg, /* 28: do a phys addr to segment selector/ offset conversion */
do_exit, /* 29: an server or driver requests to be aborted */
do_vircopy, /* 30: copy from process to process (virtual addressing) */
do_physcopy, /* 31: copy from anywhere to anywhere (physical addressing) */
};
/* Check if system call table is correct. This should not fail. No space is
* allocated here, because the dummy is declared extern. If the call vector
* is unbalanced, the array size will be negative and this won't compile.
*/
extern int dummy[sizeof(call_vec)==NR_SYS_CALLS*sizeof(call_vec[0]) ? 1 : -1];
/* Some system task variables. */
PRIVATE message m; /* used to receive requests */
/*===========================================================================*
* sys_task *
*===========================================================================*/
PUBLIC void sys_task()
{
/* Main entry point of sys_task. Get the message and dispatch on type. */
register int result;
/* 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("SYS task got illegal request from %d.\n", m.m_source);
result = EBADREQUEST; /* illegal message type */
}
/* Send a reply, unless inhibited by a handler function. */
if (result != EDONTREPLY) {
m.m_type = result; /* report status of call */
send(m.m_source, &m); /* send reply to caller */
}
}
}
/*===========================================================================*
* initialize *
*===========================================================================*/
PRIVATE void initialize(void)
{
register struct proc *rp;
int i;
/* Initialize IRQ table. */
for (i=0; i<NR_IRQ_VECTORS; i++)
irqtab[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_signalrm));
tmr_inittimer(&(rp->p_syncalrm));
tmr_inittimer(&(rp->p_flagalrm));
}
}
/*===========================================================================*
* clear_proc *
*===========================================================================*/
PUBLIC void clear_proc(proc_nr)
int proc_nr; /* slot of process to clean up */
{
register struct proc *rp, *rc;
struct proc *np, *xp;
/* 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_signalrm);
reset_timer(&rc->p_flagalrm);
reset_timer(&rc->p_syncalrm);
/* 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_callerq == NIL_PROC) continue;
if (rp->p_callerq == rc) {
/* Exiting process is on front of this queue. */
rp->p_callerq = rc->p_sendlink;
break;
} else {
/* See if exiting process is in middle of queue. */
np = rp->p_callerq;
while ( ( xp = np->p_sendlink) != NIL_PROC) {
if (xp == rc) {
np->p_sendlink = xp->p_sendlink;
break;
} else {
np = xp;
}
}
}
}
}
/* Now clean up the process table entry. Reset to defaults. */
kstrncpy(rc->p_name, "<noname>", PROC_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
}
/*===========================================================================*
* generic_handler *
*===========================================================================*/
PUBLIC int generic_handler(hook)
irq_hook_t *hook;
{
/* This function handles hardware interrupt in a generic way, according to
* the policy set with SYS_IRQCTL. This is rather complicated since different
* devices require different actions. Options are (1) do nothing, (2a) read a
* port and optionally (2b) strobe the port high or (2c) low with the value
* read, or (3) write a value to a port. Finally, the policy may or may not
* reenable IRQs. A notification is sent in all cases.
*/
irq_policy_t policy = irqtab[hook->irq].policy;
int proc_nr = irqtab[hook->irq].proc_nr;
long port = irqtab[hook->irq].port;
phys_bytes addr = irqtab[hook->irq].addr;
long mask_val = irqtab[hook->irq].mask_val;
/* Read a value from the given port. Possibly also strobe the port with the
* read value. Strobe it high by using the mask provided by the caller;
* strobe it low by writing back the value we read.
*/
if (policy & (IRQ_READ_PORT|IRQ_STROBE|IRQ_ECHO_VAL)) {
switch(policy & (IRQ_BYTE|IRQ_WORD|IRQ_LONG)) {
case IRQ_BYTE: { /* byte values */
u8_t byteval = inb(port);
if (policy & IRQ_STROBE) outb(port, byteval | mask_val);
if (policy & IRQ_ECHO_VAL) outb(port, byteval);
if (policy & IRQ_READ_PORT)
phys_copy(vir2phys(&byteval), addr, sizeof(u8_t));
break;
} case IRQ_WORD: { /* word values */
u16_t wordval = inw(port);
if (policy & IRQ_STROBE) outw(port, wordval | mask_val);
if (policy & IRQ_ECHO_VAL) outw(port, wordval);
if (policy & IRQ_READ_PORT)
phys_copy(vir2phys(&wordval), addr, sizeof(u16_t));
break;
} case IRQ_LONG: { /* long values */
u32_t longval = inl(port);
if (policy & IRQ_STROBE) outl(port, longval | mask_val);
if (policy & IRQ_ECHO_VAL) outl(port, longval);
if (policy & IRQ_READ_PORT)
phys_copy(vir2phys(&longval), addr, sizeof(u32_t));
break;
} default: /* do nothing */ ; /* wrong type flags */
}
}
/* Write a value to some port. This is straightforward. Note that both
* reading and writing is not possible, hence 'else if' instead of 'if'.
*/
else if (policy & (IRQ_WRITE_PORT)) {
switch(policy & (IRQ_BYTE|IRQ_WORD|IRQ_LONG)) {
case IRQ_BYTE: outb(port, (u8_t) mask_val); break;
case IRQ_WORD: outw(port, (u16_t) mask_val); break;
case IRQ_LONG: outl(port, (u32_t) mask_val); break;
default: /* do nothing */ ; /* wrong type flags */
}
}
/* Almost done, send a HARD_INT notification to allow further processing
* and possibly reenable interrupts - this depends on the policy given.
*/
notify(proc_nr, HARD_INT);
return(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 task wants to send a signal to a process. Examples of such tasks are:
* TTY wanting to cause SIGINT upon getting a DEL
* CLOCK wanting to cause SIGALRM when timer expires
* FS also uses this to send a signal, via the SYS_KILL message. Signals are
* handled by sending a message to MM. This central function handles the
* signals and makes sure the MM gets them by sending a notification. The
* process being signaled is blocked while MM 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 MM is informed, because MM can block waiting for FS to
* do a core dump.
*/
register struct proc *rp, *mmp;
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;
notify(MM_PROC_NR, KSIG_PENDING);
}
/*===========================================================================*
* 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. */
phys_bytes phys_addr;
phys_addr = (phys_bytes) vir_addr; /* no check currently! */
return phys_addr;
}
/*===========================================================================*
* 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);
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 (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));
}
#if ENABLE_MESSAGE_STATS
/*===========================================================================*
* do_mstats *
*===========================================================================*/
PRIVATE int do_mstats(m_ptr)
message *m_ptr; /* pointer to request message */
{
int r = 0;
if(m_ptr->m1_i1 > 0) {
struct message_statentry *dest;
struct proc *p;
p = proc_addr(m_ptr->m1_i3);
dest = proc_vir2phys(p, m_ptr->m1_p1);
r = mstat_copy(dest, m_ptr->m1_i1);
}
if(m_ptr->m1_i2) {
mstat_reset();
}
return r;
}
#endif /* ENABLE_MESSAGE_STATS */
/*===========================================================================*
* 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. */
phys_bytes phys_addr;
phys_addr = (phys_bytes) 0; /* no yet supported currently! */
return phys_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 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_ARG);
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;
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) {
kprintf("v_cp: Mapping failed ... phys <= 0\n", NO_ARG);
return(EFAULT);
}
}
/* Now copy bytes between physical addresseses. */
phys_copy(phys_addr[_SRC_], phys_addr[_DST_], (phys_bytes) bytes);
return(OK);
}
/*==========================================================================*
* vir_copy *
*==========================================================================*/
PUBLIC int vir_copy(src_proc, src_vir, dst_proc, dst_vir, bytes)
int src_proc; /* source process */
vir_bytes src_vir; /* source virtual address within D seg */
int dst_proc; /* destination process */
vir_bytes dst_vir; /* destination virtual address within D seg */
vir_bytes bytes; /* # of bytes to copy */
{
/* Copy bytes from one process to another. Meant for the easy cases, where
* speed isn't required. (One can normally do without one of the umaps.)
*/
phys_bytes src_phys, dst_phys;
src_phys = umap_local(proc_addr(src_proc), D, src_vir, bytes);
dst_phys = umap_local(proc_addr(dst_proc), D, dst_vir, bytes);
if (src_phys == 0 || dst_phys == 0) return(EFAULT);
phys_copy(src_phys, dst_phys, (phys_bytes) bytes);
return(OK);
}
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