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minix/servers/pm/main.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

519 lines
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/* This file contains the main program of the process manager and some related
* procedures. When MINIX starts up, the kernel runs for a little while,
* initializing itself and its tasks, and then it runs PM and VFS. Both PM
* and VFS initialize themselves as far as they can. PM asks the kernel for
* all free memory and starts serving requests.
*
* The entry points into this file are:
* main: starts PM running
* setreply: set the reply to be sent to process making an PM system call
*/
#include "pm.h"
#include <minix/keymap.h>
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/ds.h>
#include <minix/type.h>
#include <minix/endpoint.h>
#include <minix/minlib.h>
#include <minix/type.h>
#include <minix/vm.h>
#include <minix/crtso.h>
#include <signal.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/resource.h>
#include <sys/utsname.h>
#include <string.h>
#include <machine/archtypes.h>
#include <env.h>
#include "mproc.h"
#include "param.h"
#include "kernel/const.h"
#include "kernel/config.h"
#include "kernel/proc.h"
#if ENABLE_SYSCALL_STATS
EXTERN unsigned long calls_stats[NCALLS];
#endif
static void sendreply(void);
static int get_nice_value(int queue);
static void handle_vfs_reply(void);
#define click_to_round_k(n) \
((unsigned) ((((unsigned long) (n) << CLICK_SHIFT) + 512) / 1024))
/* SEF functions and variables. */
static void sef_local_startup(void);
static int sef_cb_init_fresh(int type, sef_init_info_t *info);
static int sef_cb_signal_manager(endpoint_t target, int signo);
/*===========================================================================*
* main *
*===========================================================================*/
int main()
{
/* Main routine of the process manager. */
int result;
/* SEF local startup. */
sef_local_startup();
/* This is PM's main loop- get work and do it, forever and forever. */
while (TRUE) {
int ipc_status;
/* Wait for the next message and extract useful information from it. */
if (sef_receive_status(ANY, &m_in, &ipc_status) != OK)
panic("PM sef_receive_status error");
who_e = m_in.m_source; /* who sent the message */
if(pm_isokendpt(who_e, &who_p) != OK)
panic("PM got message from invalid endpoint: %d", who_e);
call_nr = m_in.m_type; /* system call number */
/* Process slot of caller. Misuse PM's own process slot if the kernel is
* calling. This can happen in case of synchronous alarms (CLOCK) or or
* event like pending kernel signals (SYSTEM).
*/
mp = &mproc[who_p < 0 ? PM_PROC_NR : who_p];
if(who_p >= 0 && mp->mp_endpoint != who_e) {
panic("PM endpoint number out of sync with source: %d",
mp->mp_endpoint);
}
/* Drop delayed calls from exiting processes. */
if (mp->mp_flags & EXITING)
continue;
/* Check for system notifications first. Special cases. */
if (is_ipc_notify(ipc_status)) {
switch(who_p) {
case CLOCK:
expire_timers(m_in.NOTIFY_TIMESTAMP);
result = SUSPEND; /* don't reply */
break;
default :
/* ignore notify() from unknown sender */
result = SUSPEND;
}
/* done, send reply and continue */
if (result != SUSPEND) setreply(who_p, result);
sendreply();
continue;
}
switch(call_nr)
{
case PM_SETUID_REPLY:
case PM_SETGID_REPLY:
case PM_SETSID_REPLY:
case PM_EXEC_REPLY:
case PM_EXIT_REPLY:
case PM_CORE_REPLY:
case PM_FORK_REPLY:
case PM_SRV_FORK_REPLY:
case PM_UNPAUSE_REPLY:
case PM_REBOOT_REPLY:
case PM_SETGROUPS_REPLY:
if (who_e == VFS_PROC_NR)
{
handle_vfs_reply();
result= SUSPEND; /* don't reply */
}
else
result= ENOSYS;
break;
case COMMON_GETSYSINFO:
result = do_getsysinfo();
break;
default:
/* Else, if the system call number is valid, perform the
* call.
*/
if ((unsigned) call_nr >= NCALLS) {
result = ENOSYS;
} else {
#if ENABLE_SYSCALL_STATS
calls_stats[call_nr]++;
#endif
result = (*call_vec[call_nr])();
}
break;
}
/* Send reply. */
if (result != SUSPEND) setreply(who_p, result);
sendreply();
}
return(OK);
}
/*===========================================================================*
* sef_local_startup *
*===========================================================================*/
static void sef_local_startup()
{
/* Register init callbacks. */
sef_setcb_init_fresh(sef_cb_init_fresh);
sef_setcb_init_restart(sef_cb_init_fail);
/* No live update support for now. */
/* Register signal callbacks. */
sef_setcb_signal_manager(sef_cb_signal_manager);
/* Let SEF perform startup. */
sef_startup();
}
/*===========================================================================*
* sef_cb_init_fresh *
*===========================================================================*/
static int sef_cb_init_fresh(int UNUSED(type), sef_init_info_t *UNUSED(info))
{
/* Initialize the process manager.
* Memory use info is collected from the boot monitor, the kernel, and
* all processes compiled into the system image. Initially this information
* is put into an array mem_chunks. Elements of mem_chunks are struct memory,
* and hold base, size pairs in units of clicks. This array is small, there
* should be no more than 8 chunks. After the array of chunks has been built
* the contents are used to initialize the hole list. Space for the hole list
* is reserved as an array with twice as many elements as the maximum number
* of processes allowed. It is managed as a linked list, and elements of the
* array are struct hole, which, in addition to storage for a base and size in
* click units also contain space for a link, a pointer to another element.
*/
int s;
static struct boot_image image[NR_BOOT_PROCS];
register struct boot_image *ip;
static char core_sigs[] = { SIGQUIT, SIGILL, SIGTRAP, SIGABRT,
SIGEMT, SIGFPE, SIGBUS, SIGSEGV };
static char ign_sigs[] = { SIGCHLD, SIGWINCH, SIGCONT };
static char noign_sigs[] = { SIGILL, SIGTRAP, SIGEMT, SIGFPE,
SIGBUS, SIGSEGV };
register struct mproc *rmp;
register char *sig_ptr;
message mess;
/* Initialize process table, including timers. */
for (rmp=&mproc[0]; rmp<&mproc[NR_PROCS]; rmp++) {
init_timer(&rmp->mp_timer);
rmp->mp_magic = MP_MAGIC;
}
/* Build the set of signals which cause core dumps, and the set of signals
* that are by default ignored.
*/
sigemptyset(&core_sset);
for (sig_ptr = core_sigs; sig_ptr < core_sigs+sizeof(core_sigs); sig_ptr++)
sigaddset(&core_sset, *sig_ptr);
sigemptyset(&ign_sset);
for (sig_ptr = ign_sigs; sig_ptr < ign_sigs+sizeof(ign_sigs); sig_ptr++)
sigaddset(&ign_sset, *sig_ptr);
sigemptyset(&noign_sset);
for (sig_ptr = noign_sigs; sig_ptr < noign_sigs+sizeof(noign_sigs); sig_ptr++)
sigaddset(&noign_sset, *sig_ptr);
/* Obtain a copy of the boot monitor parameters and the kernel info struct.
* Parse the list of free memory chunks. This list is what the boot monitor
* reported, but it must be corrected for the kernel and system processes.
*/
if ((s=sys_getmonparams(monitor_params, sizeof(monitor_params))) != OK)
panic("get monitor params failed: %d", s);
if ((s=sys_getkinfo(&kinfo)) != OK)
panic("get kernel info failed: %d", s);
/* Initialize PM's process table. Request a copy of the system image table
* that is defined at the kernel level to see which slots to fill in.
*/
if (OK != (s=sys_getimage(image)))
panic("couldn't get image table: %d", s);
procs_in_use = 0; /* start populating table */
for (ip = &image[0]; ip < &image[NR_BOOT_PROCS]; ip++) {
if (ip->proc_nr >= 0) { /* task have negative nrs */
procs_in_use += 1; /* found user process */
/* Set process details found in the image table. */
rmp = &mproc[ip->proc_nr];
strncpy(rmp->mp_name, ip->proc_name, PROC_NAME_LEN);
(void) sigemptyset(&rmp->mp_ignore);
(void) sigemptyset(&rmp->mp_sigmask);
(void) sigemptyset(&rmp->mp_catch);
if (ip->proc_nr == INIT_PROC_NR) { /* user process */
/* INIT is root, we make it father of itself. This is
* not really OK, INIT should have no father, i.e.
* a father with pid NO_PID. But PM currently assumes
* that mp_parent always points to a valid slot number.
*/
rmp->mp_parent = INIT_PROC_NR;
rmp->mp_procgrp = rmp->mp_pid = INIT_PID;
rmp->mp_flags |= IN_USE;
/* Set scheduling info */
rmp->mp_scheduler = KERNEL;
rmp->mp_nice = get_nice_value(USR_Q);
}
else { /* system process */
if(ip->proc_nr == RS_PROC_NR) {
rmp->mp_parent = INIT_PROC_NR;
}
else {
rmp->mp_parent = RS_PROC_NR;
}
rmp->mp_pid = get_free_pid();
rmp->mp_flags |= IN_USE | PRIV_PROC;
/* RS schedules this process */
rmp->mp_scheduler = NONE;
rmp->mp_nice = get_nice_value(SRV_Q);
}
/* Get kernel endpoint identifier. */
rmp->mp_endpoint = ip->endpoint;
/* Tell VFS about this system process. */
mess.m_type = PM_INIT;
mess.PM_SLOT = ip->proc_nr;
mess.PM_PID = rmp->mp_pid;
mess.PM_PROC = rmp->mp_endpoint;
if (OK != (s=send(VFS_PROC_NR, &mess)))
panic("can't sync up with VFS: %d", s);
}
}
/* Tell VFS that no more system processes follow and synchronize. */
mess.PR_ENDPT = NONE;
if (sendrec(VFS_PROC_NR, &mess) != OK || mess.m_type != OK)
panic("can't sync up with VFS");
#if (CHIP == INTEL)
uts_val.machine[0] = 'i';
strcpy(uts_val.machine + 1, itoa(getprocessor()));
#endif
system_hz = sys_hz();
/* Initialize user-space scheduling. */
sched_init();
return(OK);
}
/*===========================================================================*
* sef_cb_signal_manager *
*===========================================================================*/
static int sef_cb_signal_manager(endpoint_t target, int signo)
{
/* Process signal on behalf of the kernel. */
int r;
r = process_ksig(target, signo);
sendreply();
return r;
}
/*===========================================================================*
* setreply *
*===========================================================================*/
void setreply(proc_nr, result)
int proc_nr; /* process to reply to */
int result; /* result of call (usually OK or error #) */
{
/* Fill in a reply message to be sent later to a user process. System calls
* may occasionally fill in other fields, this is only for the main return
* value, and for setting the "must send reply" flag.
*/
register struct mproc *rmp = &mproc[proc_nr];
if(proc_nr < 0 || proc_nr >= NR_PROCS)
panic("setreply arg out of range: %d", proc_nr);
rmp->mp_reply.reply_res = result;
rmp->mp_flags |= REPLY; /* reply pending */
}
/*===========================================================================*
* sendreply *
*===========================================================================*/
static void sendreply()
{
int proc_nr;
int s;
struct mproc *rmp;
/* Send out all pending reply messages, including the answer to
* the call just made above.
*/
for (proc_nr=0, rmp=mproc; proc_nr < NR_PROCS; proc_nr++, rmp++) {
/* In the meantime, the process may have been killed by a
* signal (e.g. if a lethal pending signal was unblocked)
* without the PM realizing it. If the slot is no longer in
* use or the process is exiting, don't try to reply.
*/
if ((rmp->mp_flags & (REPLY | IN_USE | EXITING)) ==
(REPLY | IN_USE)) {
s=sendnb(rmp->mp_endpoint, &rmp->mp_reply);
if (s != OK) {
printf("PM can't reply to %d (%s): %d\n",
rmp->mp_endpoint, rmp->mp_name, s);
}
rmp->mp_flags &= ~REPLY;
}
}
}
/*===========================================================================*
* get_nice_value *
*===========================================================================*/
static int get_nice_value(queue)
int queue; /* store mem chunks here */
{
/* Processes in the boot image have a priority assigned. The PM doesn't know
* about priorities, but uses 'nice' values instead. The priority is between
* MIN_USER_Q and MAX_USER_Q. We have to scale between PRIO_MIN and PRIO_MAX.
*/
int nice_val = (queue - USER_Q) * (PRIO_MAX-PRIO_MIN+1) /
(MIN_USER_Q-MAX_USER_Q+1);
if (nice_val > PRIO_MAX) nice_val = PRIO_MAX; /* shouldn't happen */
if (nice_val < PRIO_MIN) nice_val = PRIO_MIN; /* shouldn't happen */
return nice_val;
}
/*===========================================================================*
* handle_vfs_reply *
*===========================================================================*/
static void handle_vfs_reply()
{
struct mproc *rmp;
endpoint_t proc_e;
int r, proc_n;
/* PM_REBOOT is the only request not associated with a process.
* Handle its reply first.
*/
if (call_nr == PM_REBOOT_REPLY) {
/* Ask the kernel to abort. All system services, including
* the PM, will get a HARD_STOP notification. Await the
* notification in the main loop.
*/
sys_abort(RBT_DEFAULT);
return;
}
/* Get the process associated with this call */
proc_e = m_in.PM_PROC;
if (pm_isokendpt(proc_e, &proc_n) != OK) {
panic("handle_vfs_reply: got bad endpoint from VFS: %d", proc_e);
}
rmp = &mproc[proc_n];
/* Now that VFS replied, mark the process as VFS-idle again */
if (!(rmp->mp_flags & VFS_CALL))
panic("handle_vfs_reply: reply without request: %d", call_nr);
rmp->mp_flags &= ~VFS_CALL;
if (rmp->mp_flags & UNPAUSED)
panic("handle_vfs_reply: UNPAUSED set on entry: %d", call_nr);
/* Call-specific handler code */
switch (call_nr) {
case PM_SETUID_REPLY:
case PM_SETGID_REPLY:
case PM_SETGROUPS_REPLY:
/* Wake up the original caller */
setreply(rmp-mproc, OK);
break;
case PM_SETSID_REPLY:
/* Wake up the original caller */
setreply(rmp-mproc, rmp->mp_procgrp);
break;
case PM_EXEC_REPLY:
exec_restart(rmp, m_in.PM_STATUS, (vir_bytes)m_in.PM_PC,
(vir_bytes)m_in.PM_NEWSP);
break;
case PM_EXIT_REPLY:
exit_restart(rmp, FALSE /*dump_core*/);
break;
case PM_CORE_REPLY:
if (m_in.PM_STATUS == OK)
rmp->mp_sigstatus |= DUMPED;
if (m_in.PM_PROC == m_in.PM_TRACED_PROC)
/* The reply is to a core dump request
* for a killed process */
exit_restart(rmp, TRUE /*dump_core*/);
else
/* The reply is to a core dump request
* for a traced process (T_DUMPCORE) */
/* Wake up the original caller */
setreply(rmp-mproc, rmp->mp_procgrp);
break;
case PM_FORK_REPLY:
/* Schedule the newly created process ... */
r = (OK);
if (rmp->mp_scheduler != KERNEL && rmp->mp_scheduler != NONE) {
r = sched_start_user(rmp->mp_scheduler, rmp);
}
/* If scheduling the process failed, we want to tear down the process
* and fail the fork */
if (r != (OK)) {
/* Tear down the newly created process */
rmp->mp_scheduler = NONE; /* don't try to stop scheduling */
exit_proc(rmp, -1, FALSE /*dump_core*/);
/* Wake up the parent with a failed fork */
setreply(rmp->mp_parent, -1);
}
else {
/* Wake up the child */
setreply(proc_n, OK);
/* Wake up the parent */
setreply(rmp->mp_parent, rmp->mp_pid);
}
break;
case PM_SRV_FORK_REPLY:
/* Nothing to do */
break;
case PM_UNPAUSE_REPLY:
/* Process is now unpaused */
rmp->mp_flags |= UNPAUSED;
break;
default:
panic("handle_vfs_reply: unknown reply code: %d", call_nr);
}
/* Now that the process is idle again, look at pending signals */
if ((rmp->mp_flags & (IN_USE | EXITING)) == IN_USE)
restart_sigs(rmp);
}
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