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minix/servers/vm/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

489 lines
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#define _POSIX_SOURCE 1
#define _MINIX 1
#define _SYSTEM 1
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/config.h>
#include <minix/const.h>
#include <minix/ds.h>
#include <minix/endpoint.h>
#include <minix/keymap.h>
#include <minix/minlib.h>
#include <minix/type.h>
#include <minix/ipc.h>
#include <minix/sysutil.h>
#include <minix/syslib.h>
#include <minix/const.h>
#include <minix/bitmap.h>
#include <minix/crtso.h>
#include <minix/rs.h>
#include <libexec.h>
#include <ctype.h>
#include <errno.h>
#include <string.h>
#include <env.h>
#include <stdio.h>
#include <assert.h>
#include <memory.h>
#define _MAIN 1
#include "glo.h"
#include "proto.h"
#include "util.h"
#include "vm.h"
#include "sanitycheck.h"
extern int missing_spares;
#include <machine/archtypes.h>
#include <sys/param.h>
#include "kernel/const.h"
#include "kernel/config.h"
#include "kernel/proc.h"
#include <signal.h>
/* Table of calls and a macro to test for being in range. */
struct {
int (*vmc_func)(message *); /* Call handles message. */
char *vmc_name; /* Human-readable string. */
} vm_calls[NR_VM_CALLS];
/* Macro to verify call range and map 'high' range to 'base' range
* (starting at 0) in one. Evaluates to zero-based call number if call
* number is valid, returns -1 otherwise.
*/
#define CALLNUMBER(c) (((c) >= VM_RQ_BASE && \
(c) < VM_RQ_BASE + ELEMENTS(vm_calls)) ? \
((c) - VM_RQ_BASE) : -1)
static int map_service(struct rprocpub *rpub);
static int vm_acl_ok(endpoint_t caller, int call);
static int do_rs_init(message *m);
/* SEF functions and variables. */
static void sef_cb_signal_handler(int signo);
void init_vm(void);
/*===========================================================================*
* main *
*===========================================================================*/
int main(void)
{
message msg;
int result, who_e, rcv_sts;
int caller_slot;
struct vmproc *vmp_caller;
/* Initialize system so that all processes are runnable */
init_vm();
/* Register init callbacks. */
sef_setcb_init_restart(sef_cb_init_fail);
sef_setcb_signal_handler(sef_cb_signal_handler);
/* Let SEF perform startup. */
sef_startup();
SANITYCHECK(SCL_TOP);
/* This is VM's main loop. */
while (TRUE) {
int r, c;
SANITYCHECK(SCL_TOP);
if(missing_spares > 0) {
pt_cycle(); /* pagetable code wants to be called */
}
if ((r=sef_receive_status(ANY, &msg, &rcv_sts)) != OK)
panic("sef_receive_status() error: %d", r);
if (is_ipc_notify(rcv_sts)) {
/* Unexpected notify(). */
printf("VM: ignoring notify() from %d\n", msg.m_source);
continue;
}
who_e = msg.m_source;
if(vm_isokendpt(who_e, &caller_slot) != OK)
panic("invalid caller %d", who_e);
vmp_caller = &vmproc[caller_slot];
c = CALLNUMBER(msg.m_type);
result = ENOSYS; /* Out of range or restricted calls return this. */
if(msg.m_type == RS_INIT && msg.m_source == RS_PROC_NR) {
result = do_rs_init(&msg);
} else if (msg.m_type == VM_PAGEFAULT) {
if (!IPC_STATUS_FLAGS_TEST(rcv_sts, IPC_FLG_MSG_FROM_KERNEL)) {
printf("VM: process %d faked VM_PAGEFAULT "
"message!\n", msg.m_source);
}
do_pagefaults(&msg);
pt_clearmapcache();
/*
* do not reply to this call, the caller is unblocked by
* a sys_vmctl() call in do_pagefaults if success. VM panics
* otherwise
*/
continue;
} else if(c < 0 || !vm_calls[c].vmc_func) {
/* out of range or missing callnr */
} else {
if (vm_acl_ok(who_e, c) != OK) {
printf("VM: unauthorized %s by %d\n",
vm_calls[c].vmc_name, who_e);
} else {
SANITYCHECK(SCL_FUNCTIONS);
result = vm_calls[c].vmc_func(&msg);
SANITYCHECK(SCL_FUNCTIONS);
}
}
/* Send reply message, unless the return code is SUSPEND,
* which is a pseudo-result suppressing the reply message.
*/
if(result != SUSPEND) {
msg.m_type = result;
if((r=send(who_e, &msg)) != OK) {
printf("VM: couldn't send %d to %d (err %d)\n",
msg.m_type, who_e, r);
panic("send() error");
}
}
}
return(OK);
}
static int do_rs_init(message *m)
{
int s, i;
static struct rprocpub rprocpub[NR_BOOT_PROCS];
/* Map all the services in the boot image. */
if((s = sys_safecopyfrom(RS_PROC_NR, m->RS_INIT_RPROCTAB_GID, 0,
(vir_bytes) rprocpub, sizeof(rprocpub))) != OK) {
panic("vm: sys_safecopyfrom (rs) failed: %d", s);
}
for(i=0;i < NR_BOOT_PROCS;i++) {
if(rprocpub[i].in_use) {
if((s = map_service(&rprocpub[i])) != OK) {
panic("unable to map service: %d", s);
}
}
}
/* RS expects this response that it then again wants to reply to: */
m->RS_INIT_RESULT = OK;
sendrec(RS_PROC_NR, m);
return(SUSPEND);
}
struct vmproc *init_proc(endpoint_t ep_nr)
{
static struct boot_image *ip;
for (ip = &kernel_boot_info.boot_procs[0];
ip < &kernel_boot_info.boot_procs[NR_BOOT_PROCS]; ip++) {
struct vmproc *vmp;
if(ip->proc_nr != ep_nr) continue;
if(ip->proc_nr >= _NR_PROCS || ip->proc_nr < 0)
panic("proc: %d", ip->proc_nr);
vmp = &vmproc[ip->proc_nr];
assert(!(vmp->vm_flags & VMF_INUSE)); /* no double procs */
clear_proc(vmp);
vmp->vm_flags = VMF_INUSE;
vmp->vm_endpoint = ip->endpoint;
vmp->vm_boot = ip;
return vmp;
}
panic("no init_proc");
}
struct vm_exec_info {
struct exec_info execi;
struct boot_image *ip;
struct vmproc *vmp;
};
static int libexec_copy_physcopy(struct exec_info *execi,
off_t off, off_t vaddr, size_t len)
{
vir_bytes end;
struct vm_exec_info *ei = execi->opaque;
end = ei->ip->start_addr + ei->ip->len;
assert(ei->ip->start_addr + off + len <= end);
return sys_physcopy(NONE, ei->ip->start_addr + off,
execi->proc_e, vaddr, len);
}
static void boot_alloc(struct exec_info *execi, off_t vaddr,
size_t len, int flags)
{
struct vmproc *vmp = ((struct vm_exec_info *) execi->opaque)->vmp;
if(!(map_page_region(vmp, vaddr, 0,
len, MAP_NONE, VR_ANON | VR_WRITABLE | VR_UNINITIALIZED, flags))) {
panic("VM: exec: map_page_region for boot process failed");
}
}
static int libexec_alloc_vm_prealloc(struct exec_info *execi,
off_t vaddr, size_t len)
{
boot_alloc(execi, vaddr, len, MF_PREALLOC);
return OK;
}
static int libexec_alloc_vm_ondemand(struct exec_info *execi,
off_t vaddr, size_t len)
{
boot_alloc(execi, vaddr, len, 0);
return OK;
}
void exec_bootproc(struct vmproc *vmp, struct boot_image *ip)
{
struct vm_exec_info vmexeci;
struct exec_info *execi = &vmexeci.execi;
char hdr[VM_PAGE_SIZE];
memset(&vmexeci, 0, sizeof(vmexeci));
if(pt_new(&vmp->vm_pt) != OK)
panic("VM: no new pagetable");
if(pt_bind(&vmp->vm_pt, vmp) != OK)
panic("VM: pt_bind failed");
if(sys_physcopy(NONE, ip->start_addr, SELF,
(vir_bytes) hdr, sizeof(hdr)) != OK)
panic("can't look at boot proc header");
execi->stack_high = kernel_boot_info.user_sp;
execi->stack_size = DEFAULT_STACK_LIMIT;
execi->proc_e = vmp->vm_endpoint;
execi->hdr = hdr;
execi->hdr_len = sizeof(hdr);
strcpy(execi->progname, ip->proc_name);
execi->frame_len = 0;
execi->opaque = &vmexeci;
vmexeci.ip = ip;
vmexeci.vmp = vmp;
/* callback functions and data */
execi->copymem = libexec_copy_physcopy;
execi->clearproc = NULL;
execi->clearmem = libexec_clear_sys_memset;
execi->allocmem_prealloc = libexec_alloc_vm_prealloc;
execi->allocmem_ondemand = libexec_alloc_vm_ondemand;
if(libexec_load_elf(execi) != OK)
panic("vm: boot process load of %d failed\n", vmp->vm_endpoint);
if(sys_exec(vmp->vm_endpoint, (char *) execi->stack_high - 12,
(char *) ip->proc_name, execi->pc) != OK)
panic("vm: boot process exec of %d failed\n", vmp->vm_endpoint);
}
void init_vm(void)
{
int s, i;
static struct memory mem_chunks[NR_MEMS];
static struct boot_image *ip;
#if SANITYCHECKS
incheck = nocheck = 0;
#endif
/* Retrieve various crucial boot parameters */
if(OK != (s=sys_getkinfo(&kernel_boot_info))) {
panic("couldn't get bootinfo: %d", s);
}
/* Sanity check */
assert(kernel_boot_info.mmap_size > 0);
assert(kernel_boot_info.mods_with_kernel > 0);
#if SANITYCHECKS
env_parse("vm_sanitychecklevel", "d", 0, &vm_sanitychecklevel, 0, SCL_MAX);
vm_sanitychecklevel = 1;
#endif
/* Get chunks of available memory. */
get_mem_chunks(mem_chunks);
/* Set table to 0. This invalidates all slots (clear VMF_INUSE). */
memset(vmproc, 0, sizeof(vmproc));
for(i = 0; i < ELEMENTS(vmproc); i++) {
vmproc[i].vm_slot = i;
}
/* region management initialization. */
map_region_init();
/* Architecture-dependent initialization. */
init_proc(VM_PROC_NR);
pt_init();
/* Initialize tables to all physical memory. */
mem_init(mem_chunks);
meminit_done = 1;
/* Give these processes their own page table. */
for (ip = &kernel_boot_info.boot_procs[0];
ip < &kernel_boot_info.boot_procs[NR_BOOT_PROCS]; ip++) {
struct vmproc *vmp;
if(ip->proc_nr < 0) continue;
assert(ip->start_addr);
/* VM has already been set up by the kernel and pt_init().
* Any other boot process is already in memory and is set up
* here.
*/
if(ip->proc_nr == VM_PROC_NR) continue;
vmp = init_proc(ip->proc_nr);
exec_bootproc(vmp, ip);
/* Free the file blob */
assert(!(ip->start_addr % VM_PAGE_SIZE));
ip->len = roundup(ip->len, VM_PAGE_SIZE);
free_mem(ABS2CLICK(ip->start_addr), ABS2CLICK(ip->len));
}
/* Set up table of calls. */
#define CALLMAP(code, func) { int i; \
if((i=CALLNUMBER(code)) < 0) { panic(#code " invalid: %d", (code)); } \
if(i >= NR_VM_CALLS) { panic(#code " invalid: %d", (code)); } \
vm_calls[i].vmc_func = (func); \
vm_calls[i].vmc_name = #code; \
}
/* Set call table to 0. This invalidates all calls (clear
* vmc_func).
*/
memset(vm_calls, 0, sizeof(vm_calls));
/* Basic VM calls. */
CALLMAP(VM_MMAP, do_mmap);
CALLMAP(VM_MUNMAP, do_munmap);
CALLMAP(VM_MUNMAP_TEXT, do_munmap);
CALLMAP(VM_MAP_PHYS, do_map_phys);
CALLMAP(VM_UNMAP_PHYS, do_unmap_phys);
/* Calls from PM. */
CALLMAP(VM_EXIT, do_exit);
CALLMAP(VM_FORK, do_fork);
CALLMAP(VM_BRK, do_brk);
CALLMAP(VM_PUSH_SIG, do_push_sig);
CALLMAP(VM_WILLEXIT, do_willexit);
CALLMAP(VM_ADDDMA, do_adddma);
CALLMAP(VM_DELDMA, do_deldma);
CALLMAP(VM_GETDMA, do_getdma);
CALLMAP(VM_NOTIFY_SIG, do_notify_sig);
/* Calls from RS */
CALLMAP(VM_RS_SET_PRIV, do_rs_set_priv);
CALLMAP(VM_RS_UPDATE, do_rs_update);
CALLMAP(VM_RS_MEMCTL, do_rs_memctl);
/* Calls from RS/VFS */
CALLMAP(VM_PROCCTL, do_procctl);
/* Generic calls. */
CALLMAP(VM_REMAP, do_remap);
CALLMAP(VM_REMAP_RO, do_remap);
CALLMAP(VM_GETPHYS, do_get_phys);
CALLMAP(VM_SHM_UNMAP, do_shared_unmap);
CALLMAP(VM_GETREF, do_get_refcount);
CALLMAP(VM_INFO, do_info);
CALLMAP(VM_QUERY_EXIT, do_query_exit);
CALLMAP(VM_WATCH_EXIT, do_watch_exit);
CALLMAP(VM_FORGETBLOCKS, do_forgetblocks);
CALLMAP(VM_FORGETBLOCK, do_forgetblock);
CALLMAP(VM_YIELDBLOCKGETBLOCK, do_yieldblockgetblock);
/* Initialize the structures for queryexit */
init_query_exit();
}
/*===========================================================================*
* sef_cb_signal_handler *
*===========================================================================*/
static void sef_cb_signal_handler(int signo)
{
/* Check for known kernel signals, ignore anything else. */
switch(signo) {
/* There is a pending memory request from the kernel. */
case SIGKMEM:
do_memory();
break;
}
/* It can happen that we get stuck receiving signals
* without sef_receive() returning. We could need more memory
* though.
*/
if(missing_spares > 0) {
pt_cycle(); /* pagetable code wants to be called */
}
pt_clearmapcache();
}
/*===========================================================================*
* map_service *
*===========================================================================*/
static int map_service(rpub)
struct rprocpub *rpub;
{
/* Map a new service by initializing its call mask. */
int r, proc_nr;
if ((r = vm_isokendpt(rpub->endpoint, &proc_nr)) != OK) {
return r;
}
/* Copy the call mask. */
memcpy(&vmproc[proc_nr].vm_call_mask, &rpub->vm_call_mask,
sizeof(vmproc[proc_nr].vm_call_mask));
return(OK);
}
/*===========================================================================*
* vm_acl_ok *
*===========================================================================*/
static int vm_acl_ok(endpoint_t caller, int call)
{
int n, r;
if ((r = vm_isokendpt(caller, &n)) != OK)
panic("VM: from strange source: %d", caller);
/* See if the call is allowed. */
if (!GET_BIT(vmproc[n].vm_call_mask, call)) {
return EPERM;
}
return OK;
}
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