453 lines
18 KiB
C
Executable file
453 lines
18 KiB
C
Executable file
/* This task handles the interface between the kernel and user-level servers.
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* System services can be accessed by doing a system call. System calls are
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* transformed into request messages, which are handled by this task. By
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* convention, a sys_call() is transformed in a SYS_CALL request message that
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* is handled in a function named do_call().
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*
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* A private call vector is used to map all system calls to the functions that
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* handle them. The actual handler functions are contained in separate files
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* to keep this file clean. The call vector is used in the system task's main
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* loop to handle all incoming requests.
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*
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* In addition to the main sys_task() entry point, which starts the main loop,
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* there are several other minor entry points:
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* get_priv: assign privilege structure to user or system process
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* send_sig: send a signal directly to a system process
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* cause_sig: take action to cause a signal to occur via PM
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* umap_local: map virtual address in LOCAL_SEG to physical
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* umap_remote: map virtual address in REMOTE_SEG to physical
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* umap_bios: map virtual address in BIOS_SEG to physical
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* virtual_copy: copy bytes from one virtual address to another
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* get_randomness: accumulate randomness in a buffer
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*
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* Changes:
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* Aug 04, 2005 check if system call is allowed (Jorrit N. Herder)
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* Jul 20, 2005 send signal to services with message (Jorrit N. Herder)
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* Jan 15, 2005 new, generalized virtual copy function (Jorrit N. Herder)
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* Oct 10, 2004 dispatch system calls from call vector (Jorrit N. Herder)
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* Sep 30, 2004 source code documentation updated (Jorrit N. Herder)
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*/
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#include "kernel.h"
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#include "system.h"
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#include <stdlib.h>
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#include <signal.h>
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#include <unistd.h>
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#include <sys/sigcontext.h>
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#if (CHIP == INTEL)
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#include <ibm/memory.h>
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#include "protect.h"
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#endif
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/* Declaration of the call vector that defines the mapping of system calls
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* to handler functions. The vector is initialized in sys_init() with map(),
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* which makes sure the system call numbers are ok. No space is allocated,
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* because the dummy is declared extern. If an illegal call is given, the
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* array size will be negative and this won't compile.
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*/
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PUBLIC int (*call_vec[NR_SYS_CALLS])(message *m_ptr);
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#define map(call_nr, handler) \
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{extern int dummy[NR_SYS_CALLS>(unsigned)(call_nr-KERNEL_CALL) ? 1:-1];} \
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call_vec[(call_nr-KERNEL_CALL)] = (handler)
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FORWARD _PROTOTYPE( void initialize, (void));
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/*===========================================================================*
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* sys_task *
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*===========================================================================*/
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PUBLIC void sys_task()
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{
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/* Main entry point of sys_task. Get the message and dispatch on type. */
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static message m;
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register int result;
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register struct proc *caller_ptr;
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unsigned int call_nr;
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int s;
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/* Initialize the system task. */
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initialize();
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while (TRUE) {
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/* Get work. Block and wait until a request message arrives. */
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receive(ANY, &m);
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call_nr = (unsigned) m.m_type - KERNEL_CALL;
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caller_ptr = proc_addr(m.m_source);
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/* See if the caller made a valid request and try to handle it. */
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if (! (priv(caller_ptr)->s_call_mask & (1<<call_nr)) &&
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m.m_type != SYS_IOPENABLE ) {
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kprintf("SYSTEM: request %d from %d denied.\n", call_nr,m.m_source);
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result = ECALLDENIED; /* illegal message type */
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} else if (call_nr >= NR_SYS_CALLS) { /* check call number */
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kprintf("SYSTEM: illegal request %d from %d.\n", call_nr,m.m_source);
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result = EBADREQUEST; /* illegal message type */
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}
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else {
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result = (*call_vec[call_nr])(&m); /* handle the system call */
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}
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/* Send a reply, unless inhibited by a handler function. Use the kernel
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* function lock_send() to prevent a system call trap. The destination
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* is known to be blocked waiting for a message.
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*/
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if (result != EDONTREPLY) {
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m.m_type = result; /* report status of call */
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if (OK != (s=lock_send(m.m_source, &m))) {
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kprintf("SYSTEM, reply to %d failed: %d\n", m.m_source, s);
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}
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}
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}
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}
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/*===========================================================================*
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* initialize *
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*===========================================================================*/
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PRIVATE void initialize(void)
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{
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register struct priv *sp;
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int i;
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/* Initialize IRQ handler hooks. Mark all hooks available. */
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for (i=0; i<NR_IRQ_HOOKS; i++) {
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irq_hooks[i].proc_nr = NONE;
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}
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/* Initialize all alarm timers for all processes. */
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for (sp=BEG_PRIV_ADDR; sp < END_PRIV_ADDR; sp++) {
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tmr_inittimer(&(sp->s_alarm_timer));
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}
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/* Initialize the call vector to a safe default handler. Some system calls
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* may be disabled or nonexistant. Then explicitely map known calls to their
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* handler functions. This is done with a macro that gives a compile error
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* if an illegal call number is used. The ordering is not important here.
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*/
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for (i=0; i<NR_SYS_CALLS; i++) {
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call_vec[i] = do_unused;
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}
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/* Process management. */
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map(SYS_FORK, do_fork); /* a process forked a new process */
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map(SYS_EXEC, do_exec); /* update process after execute */
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map(SYS_EXIT, do_exit); /* clean up after process exit */
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map(SYS_NICE, do_nice); /* set scheduling priority */
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map(SYS_PRIVCTL, do_privctl); /* system privileges control */
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map(SYS_TRACE, do_trace); /* request a trace operation */
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/* Signal handling. */
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map(SYS_KILL, do_kill); /* cause a process to be signaled */
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map(SYS_GETKSIG, do_getksig); /* PM checks for pending signals */
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map(SYS_ENDKSIG, do_endksig); /* PM finished processing signal */
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map(SYS_SIGSEND, do_sigsend); /* start POSIX-style signal */
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map(SYS_SIGRETURN, do_sigreturn); /* return from POSIX-style signal */
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/* Device I/O. */
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map(SYS_IRQCTL, do_irqctl); /* interrupt control operations */
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map(SYS_DEVIO, do_devio); /* inb, inw, inl, outb, outw, outl */
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map(SYS_SDEVIO, do_sdevio); /* phys_insb, _insw, _outsb, _outsw */
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map(SYS_VDEVIO, do_vdevio); /* vector with devio requests */
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map(SYS_INT86, do_int86); /* real-mode BIOS calls */
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/* Memory management. */
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map(SYS_NEWMAP, do_newmap); /* set up a process memory map */
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map(SYS_SEGCTL, do_segctl); /* add segment and get selector */
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map(SYS_MEMSET, do_memset); /* write char to memory area */
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map(SYS_VM_SETBUF, do_vm_setbuf); /* PM passes buffer for page tables */
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map(SYS_VM_MAP, do_vm_map); /* Map/unmap physical (device) memory */
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/* Copying. */
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map(SYS_UMAP, do_umap); /* map virtual to physical address */
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map(SYS_VIRCOPY, do_vircopy); /* use pure virtual addressing */
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map(SYS_PHYSCOPY, do_physcopy); /* use physical addressing */
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map(SYS_VIRVCOPY, do_virvcopy); /* vector with copy requests */
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map(SYS_PHYSVCOPY, do_physvcopy); /* vector with copy requests */
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/* Clock functionality. */
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map(SYS_TIMES, do_times); /* get uptime and process times */
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map(SYS_SETALARM, do_setalarm); /* schedule a synchronous alarm */
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/* System control. */
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map(SYS_ABORT, do_abort); /* abort MINIX */
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map(SYS_GETINFO, do_getinfo); /* request system information */
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map(SYS_IOPENABLE, do_iopenable); /* Enable I/O */
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}
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/*===========================================================================*
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* get_priv *
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*===========================================================================*/
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PUBLIC int get_priv(rc, proc_type)
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register struct proc *rc; /* new (child) process pointer */
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int proc_type; /* system or user process flag */
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{
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/* Get a privilege structure. All user processes share the same privilege
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* structure. System processes get their own privilege structure.
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*/
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register struct priv *sp; /* privilege structure */
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if (proc_type == SYS_PROC) { /* find a new slot */
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for (sp = BEG_PRIV_ADDR; sp < END_PRIV_ADDR; ++sp)
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if (sp->s_proc_nr == NONE && sp->s_id != USER_PRIV_ID) break;
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if (sp->s_proc_nr != NONE) return(ENOSPC);
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rc->p_priv = sp; /* assign new slot */
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rc->p_priv->s_proc_nr = proc_nr(rc); /* set association */
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rc->p_priv->s_flags = SYS_PROC; /* mark as privileged */
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} else {
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rc->p_priv = &priv[USER_PRIV_ID]; /* use shared slot */
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rc->p_priv->s_proc_nr = INIT_PROC_NR; /* set association */
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rc->p_priv->s_flags = 0; /* no initial flags */
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}
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return(OK);
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}
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/*===========================================================================*
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* get_randomness *
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*===========================================================================*/
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PUBLIC void get_randomness(source)
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int source;
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{
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/* On machines with the RDTSC (cycle counter read instruction - pentium
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* and up), use that for high-resolution raw entropy gathering. Otherwise,
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* use the realtime clock (tick resolution).
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*
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* Unfortunately this test is run-time - we don't want to bother with
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* compiling different kernels for different machines.
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*
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* On machines without RDTSC, we use read_clock().
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*/
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int r_next;
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unsigned long tsc_high, tsc_low;
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source %= RANDOM_SOURCES;
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r_next= krandom.bin[source].r_next;
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if (machine.processor > 486) {
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read_tsc(&tsc_high, &tsc_low);
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krandom.bin[source].r_buf[r_next] = tsc_low;
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} else {
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krandom.bin[source].r_buf[r_next] = read_clock();
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}
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if (krandom.bin[source].r_size < RANDOM_ELEMENTS) {
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krandom.bin[source].r_size ++;
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}
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krandom.bin[source].r_next = (r_next + 1 ) % RANDOM_ELEMENTS;
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}
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/*===========================================================================*
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* send_sig *
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*===========================================================================*/
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PUBLIC void send_sig(proc_nr, sig_nr)
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int proc_nr; /* system process to be signalled */
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int sig_nr; /* signal to be sent, 1 to _NSIG */
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{
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/* Notify a system process about a signal. This is straightforward. Simply
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* set the signal that is to be delivered in the pending signals map and
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* send a notification with source SYSTEM.
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*/
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register struct proc *rp;
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rp = proc_addr(proc_nr);
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sigaddset(&priv(rp)->s_sig_pending, sig_nr);
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lock_notify(SYSTEM, proc_nr);
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}
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/*===========================================================================*
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* cause_sig *
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*===========================================================================*/
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PUBLIC void cause_sig(proc_nr, sig_nr)
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int proc_nr; /* process to be signalled */
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int sig_nr; /* signal to be sent, 1 to _NSIG */
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{
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/* A system process wants to send a signal to a process. Examples are:
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* - HARDWARE wanting to cause a SIGSEGV after a CPU exception
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* - TTY wanting to cause SIGINT upon getting a DEL
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* - FS wanting to cause SIGPIPE for a broken pipe
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* Signals are handled by sending a message to PM. This function handles the
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* signals and makes sure the PM gets them by sending a notification. The
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* process being signaled is blocked while PM has not finished all signals
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* for it.
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* Race conditions between calls to this function and the system calls that
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* process pending kernel signals cannot exist. Signal related functions are
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* only called when a user process causes a CPU exception and from the kernel
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* process level, which runs to completion.
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*/
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register struct proc *rp;
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/* Check if the signal is already pending. Process it otherwise. */
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rp = proc_addr(proc_nr);
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if (! sigismember(&rp->p_pending, sig_nr)) {
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sigaddset(&rp->p_pending, sig_nr);
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if (! (rp->p_rts_flags & SIGNALED)) { /* other pending */
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if (rp->p_rts_flags == 0) lock_dequeue(rp); /* make not ready */
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rp->p_rts_flags |= SIGNALED | SIG_PENDING; /* update flags */
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send_sig(PM_PROC_NR, SIGKSIG);
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}
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}
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}
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/*===========================================================================*
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* umap_bios *
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*===========================================================================*/
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PUBLIC phys_bytes umap_bios(rp, vir_addr, bytes)
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register struct proc *rp; /* pointer to proc table entry for process */
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vir_bytes vir_addr; /* virtual address in BIOS segment */
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vir_bytes bytes; /* # of bytes to be copied */
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{
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/* Calculate the physical memory address at the BIOS. Note: currently, BIOS
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* address zero (the first BIOS interrupt vector) is not considered, as an
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* error here, but since the physical address will be zero as well, the
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* calling function will think an error occurred. This is not a problem,
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* since no one uses the first BIOS interrupt vector.
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*/
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/* Check all acceptable ranges. */
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if (vir_addr >= BIOS_MEM_BEGIN && vir_addr + bytes <= BIOS_MEM_END)
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return (phys_bytes) vir_addr;
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else if (vir_addr >= BASE_MEM_TOP && vir_addr + bytes <= UPPER_MEM_END)
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return (phys_bytes) vir_addr;
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#if DEAD_CODE /* brutal fix, if the above is too restrictive */
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if (vir_addr >= BIOS_MEM_BEGIN && vir_addr + bytes <= UPPER_MEM_END)
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return (phys_bytes) vir_addr;
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#endif
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kprintf("Warning, error in umap_bios, virtual address 0x%x\n", vir_addr);
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return 0;
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}
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/*===========================================================================*
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* umap_local *
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*===========================================================================*/
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PUBLIC phys_bytes umap_local(rp, seg, vir_addr, bytes)
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register struct proc *rp; /* pointer to proc table entry for process */
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int seg; /* T, D, or S segment */
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vir_bytes vir_addr; /* virtual address in bytes within the seg */
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vir_bytes bytes; /* # of bytes to be copied */
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{
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/* Calculate the physical memory address for a given virtual address. */
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vir_clicks vc; /* the virtual address in clicks */
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phys_bytes pa; /* intermediate variables as phys_bytes */
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#if (CHIP == INTEL)
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phys_bytes seg_base;
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#endif
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/* If 'seg' is D it could really be S and vice versa. T really means T.
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* If the virtual address falls in the gap, it causes a problem. On the
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* 8088 it is probably a legal stack reference, since "stackfaults" are
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* not detected by the hardware. On 8088s, the gap is called S and
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* accepted, but on other machines it is called D and rejected.
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* The Atari ST behaves like the 8088 in this respect.
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*/
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if (bytes <= 0) return( (phys_bytes) 0);
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if (vir_addr + bytes <= vir_addr) return 0; /* overflow */
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vc = (vir_addr + bytes - 1) >> CLICK_SHIFT; /* last click of data */
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#if (CHIP == INTEL) || (CHIP == M68000)
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if (seg != T)
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seg = (vc < rp->p_memmap[D].mem_vir + rp->p_memmap[D].mem_len ? D : S);
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#else
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if (seg != T)
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seg = (vc < rp->p_memmap[S].mem_vir ? D : S);
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#endif
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if ((vir_addr>>CLICK_SHIFT) >= rp->p_memmap[seg].mem_vir +
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rp->p_memmap[seg].mem_len) return( (phys_bytes) 0 );
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if (vc >= rp->p_memmap[seg].mem_vir +
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rp->p_memmap[seg].mem_len) return( (phys_bytes) 0 );
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#if (CHIP == INTEL)
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seg_base = (phys_bytes) rp->p_memmap[seg].mem_phys;
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seg_base = seg_base << CLICK_SHIFT; /* segment origin in bytes */
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#endif
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pa = (phys_bytes) vir_addr;
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#if (CHIP != M68000)
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pa -= rp->p_memmap[seg].mem_vir << CLICK_SHIFT;
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return(seg_base + pa);
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#endif
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#if (CHIP == M68000)
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pa -= (phys_bytes)rp->p_memmap[seg].mem_vir << CLICK_SHIFT;
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pa += (phys_bytes)rp->p_memmap[seg].mem_phys << CLICK_SHIFT;
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return(pa);
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#endif
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}
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/*===========================================================================*
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* umap_remote *
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*===========================================================================*/
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PUBLIC phys_bytes umap_remote(rp, seg, vir_addr, bytes)
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register struct proc *rp; /* pointer to proc table entry for process */
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int seg; /* index of remote segment */
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vir_bytes vir_addr; /* virtual address in bytes within the seg */
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vir_bytes bytes; /* # of bytes to be copied */
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{
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/* Calculate the physical memory address for a given virtual address. */
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struct far_mem *fm;
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if (bytes <= 0) return( (phys_bytes) 0);
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if (seg < 0 || seg >= NR_REMOTE_SEGS) return( (phys_bytes) 0);
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fm = &rp->p_priv->s_farmem[seg];
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if (! fm->in_use) return( (phys_bytes) 0);
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if (vir_addr + bytes > fm->mem_len) return( (phys_bytes) 0);
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return(fm->mem_phys + (phys_bytes) vir_addr);
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}
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/*===========================================================================*
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* virtual_copy *
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*===========================================================================*/
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PUBLIC int virtual_copy(src_addr, dst_addr, bytes)
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struct vir_addr *src_addr; /* source virtual address */
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struct vir_addr *dst_addr; /* destination virtual address */
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vir_bytes bytes; /* # of bytes to copy */
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{
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/* Copy bytes from virtual address src_addr to virtual address dst_addr.
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* Virtual addresses can be in ABS, LOCAL_SEG, REMOTE_SEG, or BIOS_SEG.
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*/
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struct vir_addr *vir_addr[2]; /* virtual source and destination address */
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phys_bytes phys_addr[2]; /* absolute source and destination */
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int seg_index;
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int i;
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/* Check copy count. */
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if (bytes <= 0) return(EDOM);
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/* Do some more checks and map virtual addresses to physical addresses. */
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vir_addr[_SRC_] = src_addr;
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vir_addr[_DST_] = dst_addr;
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for (i=_SRC_; i<=_DST_; i++) {
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/* Get physical address. */
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switch((vir_addr[i]->segment & SEGMENT_TYPE)) {
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case LOCAL_SEG:
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seg_index = vir_addr[i]->segment & SEGMENT_INDEX;
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phys_addr[i] = umap_local( proc_addr(vir_addr[i]->proc_nr),
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seg_index, vir_addr[i]->offset, bytes );
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break;
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case REMOTE_SEG:
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seg_index = vir_addr[i]->segment & SEGMENT_INDEX;
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phys_addr[i] = umap_remote( proc_addr(vir_addr[i]->proc_nr),
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seg_index, vir_addr[i]->offset, bytes );
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break;
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case BIOS_SEG:
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phys_addr[i] = umap_bios( proc_addr(vir_addr[i]->proc_nr),
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vir_addr[i]->offset, bytes );
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break;
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case PHYS_SEG:
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phys_addr[i] = vir_addr[i]->offset;
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break;
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default:
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return(EINVAL);
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}
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/* Check if mapping succeeded. */
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|
if (phys_addr[i] <= 0 && vir_addr[i]->segment != PHYS_SEG)
|
|
return(EFAULT);
|
|
}
|
|
|
|
/* Now copy bytes between physical addresseses. */
|
|
phys_copy(phys_addr[_SRC_], phys_addr[_DST_], (phys_bytes) bytes);
|
|
return(OK);
|
|
}
|
|
|