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minix/kernel/system.c
Ben Gras 50e2064049 No more intel/minix segments. 
This commit removes all traces of Minix segments (the text/data/stack
memory map abstraction in the kernel) and significance of Intel segments
(hardware segments like CS, DS that add offsets to all addressing before
page table translation). This ultimately simplifies the memory layout
and addressing and makes the same layout possible on non-Intel
architectures.

There are only two types of addresses in the world now: virtual
and physical; even the kernel and processes have the same virtual
address space. Kernel and user processes can be distinguished at a
glance as processes won't use 0xF0000000 and above.

No static pre-allocated memory sizes exist any more.

Changes to booting:
        . The pre_init.c leaves the kernel and modules exactly as
          they were left by the bootloader in physical memory
        . The kernel starts running using physical addressing,
          loaded at a fixed location given in its linker script by the
          bootloader.  All code and data in this phase are linked to
          this fixed low location.
        . It makes a bootstrap pagetable to map itself to a
          fixed high location (also in linker script) and jumps to
          the high address. All code and data then use this high addressing.
        . All code/data symbols linked at the low addresses is prefixed by
          an objcopy step with __k_unpaged_*, so that that code cannot
          reference highly-linked symbols (which aren't valid yet) or vice
          versa (symbols that aren't valid any more).
        . The two addressing modes are separated in the linker script by
          collecting the unpaged_*.o objects and linking them with low
          addresses, and linking the rest high. Some objects are linked
          twice, once low and once high.
        . The bootstrap phase passes a lot of information (e.g. free memory
          list, physical location of the modules, etc.) using the kinfo
          struct.
        . After this bootstrap the low-linked part is freed.
        . The kernel maps in VM into the bootstrap page table so that VM can
          begin executing. Its first job is to make page tables for all other
          boot processes. So VM runs before RS, and RS gets a fully dynamic,
          VM-managed address space. VM gets its privilege info from RS as usual
          but that happens after RS starts running.
        . Both the kernel loading VM and VM organizing boot processes happen
	  using the libexec logic. This removes the last reason for VM to
	  still know much about exec() and vm/exec.c is gone.

Further Implementation:
        . All segments are based at 0 and have a 4 GB limit.
        . The kernel is mapped in at the top of the virtual address
          space so as not to constrain the user processes.
        . Processes do not use segments from the LDT at all; there are
          no segments in the LDT any more, so no LLDT is needed.
        . The Minix segments T/D/S are gone and so none of the
          user-space or in-kernel copy functions use them. The copy
          functions use a process endpoint of NONE to realize it's
          a physical address, virtual otherwise.
        . The umap call only makes sense to translate a virtual address
          to a physical address now.
        . Segments-related calls like newmap and alloc_segments are gone.
        . All segments-related translation in VM is gone (vir2map etc).
        . Initialization in VM is simpler as no moving around is necessary.
        . VM and all other boot processes can be linked wherever they wish
          and will be mapped in at the right location by the kernel and VM
          respectively.

Other changes:
        . The multiboot code is less special: it does not use mb_print
          for its diagnostics any more but uses printf() as normal, saving
          the output into the diagnostics buffer, only printing to the
          screen using the direct print functions if a panic() occurs.
        . The multiboot code uses the flexible 'free memory map list'
          style to receive the list of free memory if available.
        . The kernel determines the memory layout of the processes to
          a degree: it tells VM where the kernel starts and ends and
          where the kernel wants the top of the process to be. VM then
          uses this entire range, i.e. the stack is right at the top,
          and mmap()ped bits of memory are placed below that downwards,
          and the break grows upwards.

Other Consequences:
        . Every process gets its own page table as address spaces
          can't be separated any more by segments.
        . As all segments are 0-based, there is no distinction between
          virtual and linear addresses, nor between userspace and
          kernel addresses.
        . Less work is done when context switching, leading to a net
          performance increase. (8% faster on my machine for 'make servers'.)
	. The layout and configuration of the GDT makes sysenter and syscall
	  possible.
2012-07-15 22:30:15 +02:00

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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:
* get_priv: assign privilege structure to user or system process
* set_sendto_bit: allow a process to send messages to a new target
* unset_sendto_bit: disallow a process from sending messages to a target
* fill_sendto_mask: fill the target mask of a given process
* send_sig: send a signal directly to a system process
* cause_sig: take action to cause a signal to occur via a signal mgr
* sig_delay_done: tell PM that a process is not sending
* get_randomness: accumulate randomness in a buffer
* clear_endpoint: remove a process' ability to send and receive messages
* sched_proc: schedule a process
*
* Changes:
* Nov 22, 2009 get_priv supports static priv ids (Cristiano Giuffrida)
* Aug 04, 2005 check if system call is allowed (Jorrit N. Herder)
* Jul 20, 2005 send signal to services with message (Jorrit N. Herder)
* Jan 15, 2005 new, generalized virtual copy function (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)
*/
#include "debug.h"
#include "kernel.h"
#include "system.h"
#include "proc.h"
#include "vm.h"
#include "kernel/clock.h"
#include <stdlib.h>
#include <assert.h>
#include <signal.h>
#include <unistd.h>
#include <minix/endpoint.h>
#include <minix/safecopies.h>
/* 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.
*/
static int (*call_vec[NR_SYS_CALLS])(struct proc * caller, message *m_ptr);
#define map(call_nr, handler) \
{ int call_index = call_nr-KERNEL_CALL; \
assert(call_index >= 0 && call_index < NR_SYS_CALLS); \
call_vec[call_index] = (handler) ; }
static void kernel_call_finish(struct proc * caller, message *msg, int result)
{
if(result == VMSUSPEND) {
/* Special case: message has to be saved for handling
* until VM tells us it's allowed. VM has been notified
* and we must wait for its reply to restart the call.
*/
assert(RTS_ISSET(caller, RTS_VMREQUEST));
assert(caller->p_vmrequest.type == VMSTYPE_KERNELCALL);
caller->p_vmrequest.saved.reqmsg = *msg;
caller->p_misc_flags |= MF_KCALL_RESUME;
} else {
/*
* call is finished, we could have been suspended because of VM,
* remove the request message
*/
caller->p_vmrequest.saved.reqmsg.m_source = NONE;
if (result != EDONTREPLY) {
/* copy the result as a message to the original user buffer */
msg->m_source = SYSTEM;
msg->m_type = result; /* report status of call */
#if DEBUG_IPC_HOOK
hook_ipc_msgkresult(msg, caller);
#endif
if (copy_msg_to_user(msg, (message *)caller->p_delivermsg_vir)) {
printf("WARNING wrong user pointer 0x%08x from "
"process %s / %d\n",
caller->p_delivermsg_vir,
caller->p_name,
caller->p_endpoint);
cause_sig(proc_nr(caller), SIGSEGV);
}
}
}
}
static int kernel_call_dispatch(struct proc * caller, message *msg)
{
int result = OK;
int call_nr;
#if DEBUG_IPC_HOOK
hook_ipc_msgkcall(msg, caller);
#endif
call_nr = msg->m_type - KERNEL_CALL;
/* See if the caller made a valid request and try to handle it. */
if (call_nr < 0 || call_nr >= NR_SYS_CALLS) { /* check call number */
printf("SYSTEM: illegal request %d from %d.\n",
call_nr,msg->m_source);
result = EBADREQUEST; /* illegal message type */
}
else if (!GET_BIT(priv(caller)->s_k_call_mask, call_nr)) {
printf("SYSTEM: denied request %d from %d.\n",
call_nr,msg->m_source);
result = ECALLDENIED; /* illegal message type */
} else {
/* handle the system call */
if (call_vec[call_nr])
result = (*call_vec[call_nr])(caller, msg);
else {
printf("Unused kernel call %d from %d\n",
call_nr, caller->p_endpoint);
result = EBADREQUEST;
}
}
return result;
}
/*===========================================================================*
* kernel_call *
*===========================================================================*/
/*
* this function checks the basic syscall parameters and if accepted it
* dispatches its handling to the right handler
*/
void kernel_call(message *m_user, struct proc * caller)
{
int result = OK;
message msg;
caller->p_delivermsg_vir = (vir_bytes) m_user;
/*
* the ldt and cr3 of the caller process is loaded because it just've trapped
* into the kernel or was already set in switch_to_user() before we resume
* execution of an interrupted kernel call
*/
if (copy_msg_from_user(m_user, &msg) == 0) {
msg.m_source = caller->p_endpoint;
result = kernel_call_dispatch(caller, &msg);
}
else {
printf("WARNING wrong user pointer 0x%08x from process %s / %d\n",
m_user, caller->p_name, caller->p_endpoint);
cause_sig(proc_nr(caller), SIGSEGV);
return;
}
/* remember who invoked the kcall so we can bill it its time */
kbill_kcall = caller;
kernel_call_finish(caller, &msg, result);
}
/*===========================================================================*
* initialize *
*===========================================================================*/
void system_init(void)
{
register struct priv *sp;
int i;
/* Initialize IRQ handler hooks. Mark all hooks available. */
for (i=0; i<NR_IRQ_HOOKS; i++) {
irq_hooks[i].proc_nr_e = NONE;
}
/* Initialize all alarm timers for all processes. */
for (sp=BEG_PRIV_ADDR; sp < END_PRIV_ADDR; sp++) {
tmr_inittimer(&(sp->s_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] = NULL;
}
/* Process management. */
map(SYS_FORK, do_fork); /* a process forked a new process */
map(SYS_EXEC, do_exec); /* update process after execute */
map(SYS_CLEAR, do_clear); /* clean up after process exit */
map(SYS_EXIT, do_exit); /* a system process wants to exit */
map(SYS_PRIVCTL, do_privctl); /* system privileges control */
map(SYS_TRACE, do_trace); /* request a trace operation */
map(SYS_SETGRANT, do_setgrant); /* get/set own parameters */
map(SYS_RUNCTL, do_runctl); /* set/clear stop flag of a process */
map(SYS_UPDATE, do_update); /* update a process into another */
map(SYS_STATECTL, do_statectl); /* let a process control its state */
/* Signal handling. */
map(SYS_KILL, do_kill); /* cause a process to be signaled */
map(SYS_GETKSIG, do_getksig); /* signal manager checks for signals */
map(SYS_ENDKSIG, do_endksig); /* signal manager finished signal */
map(SYS_SIGSEND, do_sigsend); /* start POSIX-style signal */
map(SYS_SIGRETURN, do_sigreturn); /* return from POSIX-style signal */
/* Device I/O. */
map(SYS_IRQCTL, do_irqctl); /* interrupt control operations */
map(SYS_DEVIO, do_devio); /* inb, inw, inl, outb, outw, outl */
map(SYS_VDEVIO, do_vdevio); /* vector with devio requests */
/* Memory management. */
map(SYS_MEMSET, do_memset); /* write char to memory area */
map(SYS_VMCTL, do_vmctl); /* various VM process settings */
/* Copying. */
map(SYS_UMAP, do_umap); /* map virtual to physical address */
map(SYS_UMAP_REMOTE, do_umap_remote); /* do_umap for non-caller process */
map(SYS_VUMAP, do_vumap); /* vectored virtual to physical map */
map(SYS_VIRCOPY, do_vircopy); /* use pure virtual addressing */
map(SYS_PHYSCOPY, do_copy); /* use physical addressing */
map(SYS_SAFECOPYFROM, do_safecopy_from);/* copy with pre-granted permission */
map(SYS_SAFECOPYTO, do_safecopy_to); /* copy with pre-granted permission */
map(SYS_VSAFECOPY, do_vsafecopy); /* vectored safecopy */
/* Mapping. */
map(SYS_SAFEMAP, do_safemap); /* map pages from other process */
map(SYS_SAFEREVMAP, do_saferevmap); /* grantor revokes the map grant */
map(SYS_SAFEUNMAP, do_safeunmap); /* requestor unmaps the mapped pages */
/* Clock functionality. */
map(SYS_TIMES, do_times); /* get uptime and process times */
map(SYS_SETALARM, do_setalarm); /* schedule a synchronous alarm */
map(SYS_STIME, do_stime); /* set the boottime */
map(SYS_VTIMER, do_vtimer); /* set or retrieve a virtual timer */
/* System control. */
map(SYS_ABORT, do_abort); /* abort MINIX */
map(SYS_GETINFO, do_getinfo); /* request system information */
map(SYS_SYSCTL, do_sysctl); /* misc system manipulation */
/* Profiling. */
map(SYS_SPROF, do_sprofile); /* start/stop statistical profiling */
map(SYS_CPROF, do_cprofile); /* get/reset call profiling data */
map(SYS_PROFBUF, do_profbuf); /* announce locations to kernel */
/* i386-specific. */
#if _MINIX_CHIP == _CHIP_INTEL
map(SYS_READBIOS, do_readbios); /* read from BIOS locations */
map(SYS_IOPENABLE, do_iopenable); /* Enable I/O */
map(SYS_SDEVIO, do_sdevio); /* phys_insb, _insw, _outsb, _outsw */
/* Machine state switching. */
map(SYS_SETMCONTEXT, do_setmcontext); /* set machine context */
map(SYS_GETMCONTEXT, do_getmcontext); /* get machine context */
#endif
/* Scheduling */
map(SYS_SCHEDULE, do_schedule); /* reschedule a process */
map(SYS_SCHEDCTL, do_schedctl); /* change process scheduler */
}
/*===========================================================================*
* get_priv *
*===========================================================================*/
int get_priv(rc, priv_id)
register struct proc *rc; /* new (child) process pointer */
int priv_id; /* privilege id */
{
/* Allocate a new privilege structure for a system process. Privilege ids
* can be assigned either statically or dynamically.
*/
register struct priv *sp; /* privilege structure */
if(priv_id == NULL_PRIV_ID) { /* allocate slot dynamically */
for (sp = BEG_DYN_PRIV_ADDR; sp < END_DYN_PRIV_ADDR; ++sp)
if (sp->s_proc_nr == NONE) break;
if (sp >= END_DYN_PRIV_ADDR) return(ENOSPC);
}
else { /* allocate slot from id */
if(!is_static_priv_id(priv_id)) {
return EINVAL; /* invalid static priv id */
}
if(priv[priv_id].s_proc_nr != NONE) {
return EBUSY; /* slot already in use */
}
sp = &priv[priv_id];
}
rc->p_priv = sp; /* assign new slot */
rc->p_priv->s_proc_nr = proc_nr(rc); /* set association */
return(OK);
}
/*===========================================================================*
* set_sendto_bit *
*===========================================================================*/
void set_sendto_bit(const struct proc *rp, int id)
{
/* Allow a process to send messages to the process(es) associated with the
* system privilege structure with the given ID.
*/
/* Disallow the process from sending to a process privilege structure with no
* associated process, and disallow the process from sending to itself.
*/
if (id_to_nr(id) == NONE || priv_id(rp) == id) {
unset_sys_bit(priv(rp)->s_ipc_to, id);
return;
}
set_sys_bit(priv(rp)->s_ipc_to, id);
/* The process that this process can now send to, must be able to reply (or
* vice versa). Therefore, its send mask should be updated as well. Ignore
* receivers that don't support traps other than RECEIVE, they can't reply
* or send messages anyway.
*/
if (priv_addr(id)->s_trap_mask & ~((1 << RECEIVE)))
set_sys_bit(priv_addr(id)->s_ipc_to, priv_id(rp));
}
/*===========================================================================*
* unset_sendto_bit *
*===========================================================================*/
void unset_sendto_bit(const struct proc *rp, int id)
{
/* Prevent a process from sending to another process. Retain the send mask
* symmetry by also unsetting the bit for the other direction.
*/
unset_sys_bit(priv(rp)->s_ipc_to, id);
unset_sys_bit(priv_addr(id)->s_ipc_to, priv_id(rp));
}
/*===========================================================================*
* fill_sendto_mask *
*===========================================================================*/
void fill_sendto_mask(const struct proc *rp, sys_map_t *map)
{
int i;
for (i=0; i < NR_SYS_PROCS; i++) {
if (get_sys_bit(*map, i))
set_sendto_bit(rp, i);
else
unset_sendto_bit(rp, i);
}
}
/*===========================================================================*
* send_sig *
*===========================================================================*/
int send_sig(endpoint_t ep, int sig_nr)
{
/* Notify a system process about a signal. This is straightforward. Simply
* set the signal that is to be delivered in the pending signals map and
* send a notification with source SYSTEM.
*/
register struct proc *rp;
struct priv *priv;
int proc_nr;
if(!isokendpt(ep, &proc_nr) || isemptyn(proc_nr))
return EINVAL;
rp = proc_addr(proc_nr);
priv = priv(rp);
if(!priv) return ENOENT;
sigaddset(&priv->s_sig_pending, sig_nr);
mini_notify(proc_addr(SYSTEM), rp->p_endpoint);
return OK;
}
/*===========================================================================*
* cause_sig *
*===========================================================================*/
void cause_sig(proc_nr, sig_nr)
proc_nr_t proc_nr; /* process to be signalled */
int sig_nr; /* signal to be sent */
{
/* A system process wants to send a signal to a process. Examples are:
* - HARDWARE wanting to cause a SIGSEGV after a CPU exception
* - TTY wanting to cause SIGINT upon getting a DEL
* - FS wanting to cause SIGPIPE for a broken pipe
* Signals are handled by sending a message to the signal manager assigned to
* the process. This function handles the signals and makes sure the signal
* manager gets them by sending a notification. The process being signaled
* is blocked while the signal manager has not finished all signals for it.
* Race conditions between calls to this function and the system calls that
* process pending kernel signals cannot exist. Signal related functions are
* only called when a user process causes a CPU exception and from the kernel
* process level, which runs to completion.
*/
register struct proc *rp, *sig_mgr_rp;
endpoint_t sig_mgr;
int sig_mgr_proc_nr;
/* Lookup signal manager. */
rp = proc_addr(proc_nr);
sig_mgr = priv(rp)->s_sig_mgr;
if(sig_mgr == SELF) sig_mgr = rp->p_endpoint;
/* If the target is the signal manager of itself, send the signal directly. */
if(rp->p_endpoint == sig_mgr) {
if(SIGS_IS_LETHAL(sig_nr)) {
/* If the signal is lethal, see if a backup signal manager exists. */
sig_mgr = priv(rp)->s_bak_sig_mgr;
if(sig_mgr != NONE && isokendpt(sig_mgr, &sig_mgr_proc_nr)) {
priv(rp)->s_sig_mgr = sig_mgr;
priv(rp)->s_bak_sig_mgr = NONE;
sig_mgr_rp = proc_addr(sig_mgr_proc_nr);
RTS_UNSET(sig_mgr_rp, RTS_NO_PRIV);
cause_sig(proc_nr, sig_nr); /* try again with the new sig mgr. */
return;
}
/* We are out of luck. Time to panic. */
proc_stacktrace(rp);
panic("cause_sig: sig manager %d gets lethal signal %d for itself",
rp->p_endpoint, sig_nr);
}
sigaddset(&priv(rp)->s_sig_pending, sig_nr);
if(OK != send_sig(rp->p_endpoint, SIGKSIGSM))
panic("send_sig failed");
return;
}
/* Check if the signal is already pending. Process it otherwise. */
if (! sigismember(&rp->p_pending, sig_nr)) {
sigaddset(&rp->p_pending, sig_nr);
if (! (RTS_ISSET(rp, RTS_SIGNALED))) { /* other pending */
RTS_SET(rp, RTS_SIGNALED | RTS_SIG_PENDING);
if(OK != send_sig(sig_mgr, SIGKSIG))
panic("send_sig failed");
}
}
}
/*===========================================================================*
* sig_delay_done *
*===========================================================================*/
void sig_delay_done(struct proc *rp)
{
/* A process is now known not to send any direct messages.
* Tell PM that the stop delay has ended, by sending a signal to the process.
* Used for actual signal delivery.
*/
rp->p_misc_flags &= ~MF_SIG_DELAY;
cause_sig(proc_nr(rp), SIGSNDELAY);
}
/*===========================================================================*
* clear_ipc *
*===========================================================================*/
static void clear_ipc(
register struct proc *rc /* slot of process to clean up */
)
{
/* Clear IPC data for a given process slot. */
struct proc **xpp; /* iterate over caller queue */
if (RTS_ISSET(rc, RTS_SENDING)) {
int target_proc;
okendpt(rc->p_sendto_e, &target_proc);
xpp = &proc_addr(target_proc)->p_caller_q; /* destination's queue */
while (*xpp) { /* check entire queue */
if (*xpp == rc) { /* process is on the queue */
*xpp = (*xpp)->p_q_link; /* replace by next process */
#if DEBUG_ENABLE_IPC_WARNINGS
printf("endpoint %d / %s removed from queue at %d\n",
rc->p_endpoint, rc->p_name, rc->p_sendto_e);
#endif
break; /* can only be queued once */
}
xpp = &(*xpp)->p_q_link; /* proceed to next queued */
}
RTS_UNSET(rc, RTS_SENDING);
}
RTS_UNSET(rc, RTS_RECEIVING);
}
/*===========================================================================*
* clear_endpoint *
*===========================================================================*/
void clear_endpoint(rc)
register struct proc *rc; /* slot of process to clean up */
{
if(isemptyp(rc)) panic("clear_proc: empty process: %d", rc->p_endpoint);
#if DEBUG_IPC_HOOK
hook_ipc_clear(rc);
#endif
/* Make sure that the exiting process is no longer scheduled. */
RTS_SET(rc, RTS_NO_ENDPOINT);
if (priv(rc)->s_flags & SYS_PROC)
{
priv(rc)->s_asynsize= 0;
}
/* If the process happens to be queued trying to send a
* message, then it must be removed from the message queues.
*/
clear_ipc(rc);
/* Likewise, if another process was sending or receive a message to or from
* the exiting process, it must be alerted that process no longer is alive.
* Check all processes.
*/
clear_ipc_refs(rc, EDEADSRCDST);
}
/*===========================================================================*
* clear_ipc_refs *
*===========================================================================*/
void clear_ipc_refs(rc, caller_ret)
register struct proc *rc; /* slot of process to clean up */
int caller_ret; /* code to return on callers */
{
/* Clear IPC references for a given process slot. */
struct proc *rp; /* iterate over process table */
int src_id;
/* Tell processes that sent asynchronous messages to 'rc' they are not
* going to be delivered */
while ((src_id = has_pending_asend(rc, ANY)) != NULL_PRIV_ID)
cancel_async(proc_addr(id_to_nr(src_id)), rc);
for (rp = BEG_PROC_ADDR; rp < END_PROC_ADDR; rp++) {
if(isemptyp(rp))
continue;
/* Unset pending notification bits. */
unset_sys_bit(priv(rp)->s_notify_pending, priv(rc)->s_id);
/* Unset pending asynchronous messages */
unset_sys_bit(priv(rp)->s_asyn_pending, priv(rc)->s_id);
/* Check if process depends on given process. */
if (P_BLOCKEDON(rp) == rc->p_endpoint) {
rp->p_reg.retreg = caller_ret; /* return requested code */
clear_ipc(rp);
}
}
}
/*===========================================================================*
* kernel_call_resume *
*===========================================================================*/
void kernel_call_resume(struct proc *caller)
{
int result;
assert(!RTS_ISSET(caller, RTS_SLOT_FREE));
assert(!RTS_ISSET(caller, RTS_VMREQUEST));
assert(caller->p_vmrequest.saved.reqmsg.m_source == caller->p_endpoint);
/*
printf("KERNEL_CALL restart from %s / %d rts 0x%08x misc 0x%08x\n",
caller->p_name, caller->p_endpoint,
caller->p_rts_flags, caller->p_misc_flags);
*/
/* re-execute the kernel call, with MF_KCALL_RESUME still set so
* the call knows this is a retry.
*/
result = kernel_call_dispatch(caller, &caller->p_vmrequest.saved.reqmsg);
/*
* we are resuming the kernel call so we have to remove this flag so it
* can be set again
*/
caller->p_misc_flags &= ~MF_KCALL_RESUME;
kernel_call_finish(caller, &caller->p_vmrequest.saved.reqmsg, result);
}
/*===========================================================================*
* sched_proc *
*===========================================================================*/
int sched_proc(struct proc *p,
int priority,
int quantum,
int cpu)
{
/* Make sure the values given are within the allowed range.*/
if ((priority < TASK_Q && priority != -1) || priority > NR_SCHED_QUEUES)
return(EINVAL);
if (quantum < 1 && quantum != -1)
return(EINVAL);
#ifdef CONFIG_SMP
if ((cpu < 0 && cpu != -1) || (cpu > 0 && (unsigned) cpu >= ncpus))
return(EINVAL);
if (cpu != -1 && !(cpu_is_ready(cpu)))
return EBADCPU;
#endif
/* In some cases, we might be rescheduling a runnable process. In such
* a case (i.e. if we are updating the priority) we set the NO_QUANTUM
* flag before the generic unset to dequeue/enqueue the process
*/
/* FIXME this preempts the process, do we really want to do that ?*/
/* FIXME this is a problem for SMP if the processes currently runs on a
* different CPU */
if (proc_is_runnable(p)) {
#ifdef CONFIG_SMP
if (p->p_cpu != cpuid && cpu != -1 && cpu != p->p_cpu) {
smp_schedule_migrate_proc(p, cpu);
}
#endif
RTS_SET(p, RTS_NO_QUANTUM);
}
if (proc_is_runnable(p))
RTS_SET(p, RTS_NO_QUANTUM);
if (priority != -1)
p->p_priority = priority;
if (quantum != -1) {
p->p_quantum_size_ms = quantum;
p->p_cpu_time_left = ms_2_cpu_time(quantum);
}
#ifdef CONFIG_SMP
if (cpu != -1)
p->p_cpu = cpu;
#endif
/* Clear the scheduling bit and enqueue the process */
RTS_UNSET(p, RTS_NO_QUANTUM);
return OK;
}
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