sanchayanmaity/minix
1
0
Fork 0
Code Issues Pull requests Packages Projects Releases Wiki Activity
minix/servers/vm/exec.c
Ben Gras 3121eec6bd . map text (kernel's and processes') in readonly 
. map kernel in non-user
 . don't map in first pages of kernel code and data
   if possible

these first pages could actually be freed but as the
kernel isn't allowed to touch them either we can't reuse
them until VM has totally taken over page table management
and kernel doesn't rely on identity mapping any more.
2008-12-18 15:35:22 +00:00

446 lines
14 KiB
C
Raw Blame History

#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 <errno.h>
#include <assert.h>
#include <env.h>
#include <pagetable.h>
#include "glo.h"
#include "proto.h"
#include "util.h"
#include "vm.h"
#include "region.h"
#include "sanitycheck.h"
#include "memory.h"
FORWARD _PROTOTYPE( int new_mem, (struct vmproc *vmp, struct vmproc *sh_vmp,
vir_bytes text_bytes, vir_bytes data_bytes, vir_bytes bss_bytes,
vir_bytes stk_bytes, phys_bytes tot_bytes) );
/*===========================================================================*
* find_share *
*===========================================================================*/
PUBLIC struct vmproc *find_share(vmp_ign, ino, dev, ctime)
struct vmproc *vmp_ign; /* process that should not be looked at */
ino_t ino; /* parameters that uniquely identify a file */
dev_t dev;
time_t ctime;
{
/* Look for a process that is the file <ino, dev, ctime> in execution. Don't
* accidentally "find" vmp_ign, because it is the process on whose behalf this
* call is made.
*/
struct vmproc *vmp;
for (vmp = &vmproc[0]; vmp < &vmproc[NR_PROCS]; vmp++) {
if (!(vmp->vm_flags & VMF_INUSE)) continue;
if (!(vmp->vm_flags & VMF_SEPARATE)) continue;
if (vmp->vm_flags & VMF_HASPT) continue;
if (vmp == vmp_ign) continue;
if (vmp->vm_ino != ino) continue;
if (vmp->vm_dev != dev) continue;
if (vmp->vm_ctime != ctime) continue;
return vmp;
}
return(NULL);
}
/*===========================================================================*
* exec_newmem *
*===========================================================================*/
PUBLIC int do_exec_newmem(message *msg)
{
int r, proc_e, proc_n;
vir_bytes stack_top;
vir_clicks tc, dc, sc, totc, dvir, s_vir;
struct vmproc *vmp, *sh_mp;
char *ptr;
struct exec_newmem args;
SANITYCHECK(SCL_FUNCTIONS);
proc_e= msg->VMEN_ENDPOINT;
if (vm_isokendpt(proc_e, &proc_n) != OK)
{
printf("VM:exec_newmem: bad endpoint %d from %d\n",
proc_e, msg->m_source);
return ESRCH;
}
vmp= &vmproc[proc_n];
ptr= msg->VMEN_ARGSPTR;
if(msg->VMEN_ARGSSIZE != sizeof(args)) {
printf("VM:exec_newmem: args size %d != %ld\n",
msg->VMEN_ARGSSIZE, sizeof(args));
return EINVAL;
}
SANITYCHECK(SCL_DETAIL);
r= sys_datacopy(msg->m_source, (vir_bytes)ptr,
SELF, (vir_bytes)&args, sizeof(args));
if (r != OK)
vm_panic("exec_newmem: sys_datacopy failed", r);
/* Check to see if segment sizes are feasible. */
tc = ((unsigned long) args.text_bytes + CLICK_SIZE - 1) >> CLICK_SHIFT;
dc = (args.data_bytes+args.bss_bytes + CLICK_SIZE - 1) >> CLICK_SHIFT;
totc = (args.tot_bytes + CLICK_SIZE - 1) >> CLICK_SHIFT;
sc = (args.args_bytes + CLICK_SIZE - 1) >> CLICK_SHIFT;
if (dc >= totc) return(ENOEXEC); /* stack must be at least 1 click */
dvir = (args.sep_id ? 0 : tc);
s_vir = dvir + (totc - sc);
r = (dvir + dc > s_vir) ? ENOMEM : OK;
if (r != OK)
return r;
/* Can the process' text be shared with that of one already running? */
if(!vm_paged) {
sh_mp = find_share(vmp, args.st_ino, args.st_dev, args.st_ctime);
} else {
sh_mp = NULL;
}
/* Allocate new memory and release old memory. Fix map and tell
* kernel.
*/
r = new_mem(vmp, sh_mp, args.text_bytes, args.data_bytes,
args.bss_bytes, args.args_bytes, args.tot_bytes);
if (r != OK) return(r);
/* Save file identification to allow it to be shared. */
vmp->vm_ino = args.st_ino;
vmp->vm_dev = args.st_dev;
vmp->vm_ctime = args.st_ctime;
stack_top= ((vir_bytes)vmp->vm_arch.vm_seg[S].mem_vir << CLICK_SHIFT) +
((vir_bytes)vmp->vm_arch.vm_seg[S].mem_len << CLICK_SHIFT);
/* set/clear separate I&D flag */
if (args.sep_id)
vmp->vm_flags |= VMF_SEPARATE;
else
vmp->vm_flags &= ~VMF_SEPARATE;
msg->VMEN_STACK_TOP = (void *) stack_top;
msg->VMEN_FLAGS = 0;
if (!sh_mp) /* Load text if sh_mp = NULL */
msg->VMEN_FLAGS |= EXC_NM_RF_LOAD_TEXT;
return OK;
}
/*===========================================================================*
* new_mem *
*===========================================================================*/
PRIVATE int new_mem(rmp, sh_mp, text_bytes, data_bytes,
bss_bytes,stk_bytes,tot_bytes)
struct vmproc *rmp; /* process to get a new memory map */
struct vmproc *sh_mp; /* text can be shared with this process */
vir_bytes text_bytes; /* text segment size in bytes */
vir_bytes data_bytes; /* size of initialized data in bytes */
vir_bytes bss_bytes; /* size of bss in bytes */
vir_bytes stk_bytes; /* size of initial stack segment in bytes */
phys_bytes tot_bytes; /* total memory to allocate, including gap */
{
/* Allocate new memory and release the old memory. Change the map and report
* the new map to the kernel. Zero the new core image's bss, gap and stack.
*/
vir_clicks text_clicks, data_clicks, gap_clicks, stack_clicks, tot_clicks;
phys_bytes bytes, base, bss_offset;
int s, r2;
SANITYCHECK(SCL_FUNCTIONS);
/* No need to allocate text if it can be shared. */
if (sh_mp != NULL) {
text_bytes = 0;
vm_assert(!vm_paged);
}
/* Acquire the new memory. Each of the 4 parts: text, (data+bss), gap,
* and stack occupies an integral number of clicks, starting at click
* boundary. The data and bss parts are run together with no space.
*/
text_clicks = ((unsigned long) text_bytes + CLICK_SIZE - 1) >> CLICK_SHIFT;
data_clicks = (data_bytes + bss_bytes + CLICK_SIZE - 1) >> CLICK_SHIFT;
stack_clicks = (stk_bytes + CLICK_SIZE - 1) >> CLICK_SHIFT;
tot_clicks = (tot_bytes + CLICK_SIZE - 1) >> CLICK_SHIFT;
gap_clicks = tot_clicks - data_clicks - stack_clicks;
if ( (int) gap_clicks < 0) return(ENOMEM);
SANITYCHECK(SCL_DETAIL);
/* We've got memory for the new core image. Release the old one. */
if(rmp->vm_flags & VMF_HASPT) {
/* Free page table and memory allocated by pagetable functions. */
rmp->vm_flags &= ~VMF_HASPT;
free_proc(rmp);
} else {
if (find_share(rmp, rmp->vm_ino, rmp->vm_dev, rmp->vm_ctime) == NULL) {
/* No other process shares the text segment, so free it. */
FREE_MEM(rmp->vm_arch.vm_seg[T].mem_phys, rmp->vm_arch.vm_seg[T].mem_len);
}
/* Free the data and stack segments. */
FREE_MEM(rmp->vm_arch.vm_seg[D].mem_phys,
rmp->vm_arch.vm_seg[S].mem_vir
+ rmp->vm_arch.vm_seg[S].mem_len
- rmp->vm_arch.vm_seg[D].mem_vir);
}
/* We have now passed the point of no return. The old core image has been
* forever lost, memory for a new core image has been allocated. Set up
* and report new map.
*/
if(vm_paged) {
if(pt_new(&rmp->vm_pt) != OK)
vm_panic("exec_newmem: no new pagetable", NO_NUM);
SANITYCHECK(SCL_DETAIL);
proc_new(rmp,
kernel_top_bytes, /* where to start the process in the page table */
CLICK2ABS(text_clicks),/* how big is the text in bytes, page-aligned */
CLICK2ABS(data_clicks),/* how big is data+bss, page-aligned */
CLICK2ABS(stack_clicks),/* how big is stack, page-aligned */
CLICK2ABS(gap_clicks), /* how big is gap, page-aligned */
0,0, /* not preallocated */
VM_STACKTOP /* regular stack top */
);
SANITYCHECK(SCL_DETAIL);
} else {
phys_clicks new_base;
new_base = ALLOC_MEM(text_clicks + tot_clicks, 0);
if (new_base == NO_MEM) return(ENOMEM);
if (sh_mp != NULL) {
/* Share the text segment. */
rmp->vm_arch.vm_seg[T] = sh_mp->vm_arch.vm_seg[T];
} else {
rmp->vm_arch.vm_seg[T].mem_phys = new_base;
rmp->vm_arch.vm_seg[T].mem_vir = 0;
rmp->vm_arch.vm_seg[T].mem_len = text_clicks;
if (text_clicks > 0)
{
/* Zero the last click of the text segment. Otherwise the
* part of that click may remain unchanged.
*/
base = (phys_bytes)(new_base+text_clicks-1) << CLICK_SHIFT;
if ((s= sys_memset(0, base, CLICK_SIZE)) != OK)
vm_panic("new_mem: sys_memset failed", s);
}
}
/* No paging stuff. */
rmp->vm_flags &= ~VMF_HASPT;
rmp->vm_regions = NULL;
rmp->vm_arch.vm_seg[D].mem_phys = new_base + text_clicks;
rmp->vm_arch.vm_seg[D].mem_vir = 0;
rmp->vm_arch.vm_seg[D].mem_len = data_clicks;
rmp->vm_arch.vm_seg[S].mem_phys = rmp->vm_arch.vm_seg[D].mem_phys +
data_clicks + gap_clicks;
rmp->vm_arch.vm_seg[S].mem_vir = rmp->vm_arch.vm_seg[D].mem_vir +
data_clicks + gap_clicks;
rmp->vm_arch.vm_seg[S].mem_len = stack_clicks;
rmp->vm_stacktop =
CLICK2ABS(rmp->vm_arch.vm_seg[S].mem_vir +
rmp->vm_arch.vm_seg[S].mem_len);
rmp->vm_arch.vm_data_top =
(rmp->vm_arch.vm_seg[S].mem_vir +
rmp->vm_arch.vm_seg[S].mem_len) << CLICK_SHIFT;
if((r2=sys_newmap(rmp->vm_endpoint, rmp->vm_arch.vm_seg)) != OK) {
/* report new map to the kernel */
vm_panic("sys_newmap failed", r2);
}
/* Zero the bss, gap, and stack segment. */
bytes = (phys_bytes)(data_clicks + gap_clicks + stack_clicks) << CLICK_SHIFT;
base = (phys_bytes) rmp->vm_arch.vm_seg[D].mem_phys << CLICK_SHIFT;
bss_offset = (data_bytes >> CLICK_SHIFT) << CLICK_SHIFT;
base += bss_offset;
bytes -= bss_offset;
if ((s=sys_memset(0, base, bytes)) != OK) {
vm_panic("new_mem can't zero", s);
}
/* Tell kernel this thing has no page table. */
if((s=pt_bind(NULL, rmp)) != OK)
vm_panic("exec_newmem: pt_bind failed", s);
}
SANITYCHECK(SCL_FUNCTIONS);
return(OK);
}
/*===========================================================================*
* find_kernel_top *
*===========================================================================*/
PUBLIC phys_bytes find_kernel_top(void)
{
/* Find out where the kernel is, so we know where to start mapping
* user processes.
*/
u32_t kernel_top = 0;
#define MEMTOP(v, i) \
(vmproc[v].vm_arch.vm_seg[i].mem_phys + vmproc[v].vm_arch.vm_seg[i].mem_len)
vm_assert(vmproc[VMP_SYSTEM].vm_flags & VMF_INUSE);
kernel_top = MEMTOP(VMP_SYSTEM, T);
kernel_top = MAX(kernel_top, MEMTOP(VMP_SYSTEM, D));
kernel_top = MAX(kernel_top, MEMTOP(VMP_SYSTEM, S));
vm_assert(kernel_top);
return CLICK2ABS(kernel_top);
}
/*===========================================================================*
* proc_new *
*===========================================================================*/
PUBLIC int proc_new(struct vmproc *vmp,
phys_bytes vstart, /* where to start the process in page table */
phys_bytes text_bytes, /* how much code, in bytes but page aligned */
phys_bytes data_bytes, /* how much data + bss, in bytes but page aligned */
phys_bytes stack_bytes, /* stack space to reserve, in bytes, page aligned */
phys_bytes gap_bytes, /* gap bytes, page aligned */
phys_bytes text_start, /* text starts here, if preallocated, otherwise 0 */
phys_bytes data_start, /* data starts here, if preallocated, otherwise 0 */
phys_bytes stacktop
)
{
int s;
vir_bytes hole_bytes;
int prealloc;
vm_assert(!(vstart % VM_PAGE_SIZE));
vm_assert(!(text_bytes % VM_PAGE_SIZE));
vm_assert(!(data_bytes % VM_PAGE_SIZE));
vm_assert(!(stack_bytes % VM_PAGE_SIZE));
vm_assert(!(gap_bytes % VM_PAGE_SIZE));
vm_assert(!(text_start % VM_PAGE_SIZE));
vm_assert(!(data_start % VM_PAGE_SIZE));
vm_assert((!text_start && !data_start) || (text_start && data_start));
if(!map_proc_kernel(vmp)) {
printf("VM: exec: map_proc_kernel failed\n");
return ENOMEM;
}
/* Place text at start of process. */
vmp->vm_arch.vm_seg[T].mem_phys = ABS2CLICK(vstart);
vmp->vm_arch.vm_seg[T].mem_vir = 0;
vmp->vm_arch.vm_seg[T].mem_len = ABS2CLICK(text_bytes);
vmp->vm_offset = vstart;
/* page mapping flags for code */
#define TEXTFLAGS (PTF_PRESENT | PTF_USER)
SANITYCHECK(SCL_DETAIL);
if(text_bytes > 0) {
if(!map_page_region(vmp, vstart, 0, text_bytes,
text_start ? text_start : MAP_NONE,
VR_ANON | VR_WRITABLE, text_start ? 0 : MF_PREALLOC)) {
SANITYCHECK(SCL_DETAIL);
printf("VM: proc_new: map_page_region failed (text)\n");
return(ENOMEM);
}
SANITYCHECK(SCL_DETAIL);
}
SANITYCHECK(SCL_DETAIL);
/* Allocate memory for data (including bss, but not including gap
* or stack), make sure it's cleared, and map it in after text
* (if any).
*/
if(!(vmp->vm_heap = map_page_region(vmp, vstart + text_bytes, 0,
data_bytes, data_start ? data_start : MAP_NONE, VR_ANON | VR_WRITABLE,
data_start ? 0 : MF_PREALLOC))) {
printf("VM: exec: map_page_region for data failed\n");
return ENOMEM;
}
/* Tag the heap so brk() call knows which region to extend. */
map_region_set_tag(vmp->vm_heap, VRT_HEAP);
/* How many address space clicks between end of data
* and start of stack?
* stacktop is the first address after the stack, as addressed
* from within the user process.
*/
hole_bytes = stacktop - data_bytes - stack_bytes - gap_bytes;
if(!map_page_region(vmp, vstart + text_bytes + data_bytes + hole_bytes,
0, stack_bytes + gap_bytes, MAP_NONE,
VR_ANON | VR_WRITABLE, 0) != OK) {
vm_panic("map_page_region failed for stack", NO_NUM);
}
vmp->vm_arch.vm_seg[D].mem_phys = ABS2CLICK(vstart + text_bytes);
vmp->vm_arch.vm_seg[D].mem_vir = 0;
vmp->vm_arch.vm_seg[D].mem_len = ABS2CLICK(data_bytes);
vmp->vm_arch.vm_seg[S].mem_phys = ABS2CLICK(vstart +
text_bytes + data_bytes + gap_bytes + hole_bytes);
vmp->vm_arch.vm_seg[S].mem_vir = ABS2CLICK(data_bytes + gap_bytes + hole_bytes);
/* Pretend the stack is the full size of the data segment, so
* we get a full-sized data segment, up to VM_DATATOP.
* After sys_newmap(), change the stack to what we know the
* stack to be (up to stacktop).
*/
vmp->vm_arch.vm_seg[S].mem_len = (VM_DATATOP >> CLICK_SHIFT) -
vmp->vm_arch.vm_seg[S].mem_vir - ABS2CLICK(vstart) - ABS2CLICK(text_bytes);
/* Where are we allowed to start using the rest of the virtual
* address space?
*/
vmp->vm_stacktop = stacktop;
/* What is the final size of the data segment in bytes? */
vmp->vm_arch.vm_data_top =
(vmp->vm_arch.vm_seg[S].mem_vir +
vmp->vm_arch.vm_seg[S].mem_len) << CLICK_SHIFT;
vmp->vm_flags |= VMF_HASPT;
if((s=sys_newmap(vmp->vm_endpoint, vmp->vm_arch.vm_seg)) != OK) {
vm_panic("sys_newmap (vm) failed", s);
}
/* This is the real stack clicks. */
vmp->vm_arch.vm_seg[S].mem_len = ABS2CLICK(stack_bytes);
if((s=pt_bind(&vmp->vm_pt, vmp)) != OK)
vm_panic("exec_newmem: pt_bind failed", s);
return OK;
}
Reference in a new issue View git blame Copy permalink