minix/servers/vm/pagefaults.c

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#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/safecopies.h>
#include <minix/bitmap.h>
#include <errno.h>
#include <string.h>
#include <env.h>
#include <stdio.h>
#include <fcntl.h>
#include <signal.h>
#include <pagefaults.h>
#include "glo.h"
#include "proto.h"
#include "memory.h"
#include "util.h"
#include "region.h"
/*===========================================================================*
* pf_errstr *
*===========================================================================*/
char *pf_errstr(u32_t err)
{
static char buf[100];
sprintf(buf, "err 0x%lx ", err);
if(PFERR_NOPAGE(err)) strcat(buf, "nopage ");
if(PFERR_PROT(err)) strcat(buf, "protection ");
if(PFERR_WRITE(err)) strcat(buf, "write");
if(PFERR_READ(err)) strcat(buf, "read");
return buf;
}
/*===========================================================================*
* do_pagefaults *
*===========================================================================*/
PUBLIC void do_pagefaults(void)
{
endpoint_t ep;
u32_t addr, err;
struct vmproc *vmp;
int r, s;
while((r=arch_get_pagefault(&ep, &addr, &err)) == OK) {
struct vir_region *region;
vir_bytes offset;
int p, wr = PFERR_WRITE(err);
if(vm_isokendpt(ep, &p) != OK)
vm_panic("do_pagefaults: endpoint wrong", ep);
vmp = &vmproc[p];
vm_assert(vmp->vm_flags & VMF_INUSE);
/* See if address is valid at all. */
if(!(region = map_lookup(vmp, addr))) {
vm_assert(PFERR_NOPAGE(err));
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printf("VM: pagefault: SIGSEGV %d bad addr 0x%lx %s\n",
ep, arch_map2vir(vmp, addr), pf_errstr(err));
sys_sysctl_stacktrace(vmp->vm_endpoint);
if((s=sys_kill(vmp->vm_endpoint, SIGSEGV)) != OK)
vm_panic("sys_kill failed", s);
if((s=sys_vmctl(ep, VMCTL_CLEAR_PAGEFAULT, r)) != OK)
vm_panic("do_pagefaults: sys_vmctl failed", ep);
continue;
}
/* Make sure this isn't a region that isn't supposed
* to cause pagefaults.
*/
vm_assert(!(region->flags & VR_NOPF));
/* We do not allow shared memory to cause pagefaults.
* These pages have to be pre-allocated.
*/
vm_assert(!(region->flags & VR_SHARED));
/* If process was writing, see if it's writable. */
if(!(region->flags & VR_WRITABLE) && wr) {
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printf("VM: pagefault: SIGSEGV %d ro map 0x%lx %s\n",
ep, arch_map2vir(vmp, addr), pf_errstr(err));
sys_sysctl_stacktrace(vmp->vm_endpoint);
if((s=sys_kill(vmp->vm_endpoint, SIGSEGV)) != OK)
vm_panic("sys_kill failed", s);
if((s=sys_vmctl(ep, VMCTL_CLEAR_PAGEFAULT, r)) != OK)
vm_panic("do_pagefaults: sys_vmctl failed", ep);
continue;
}
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vm_assert(addr >= region->vaddr);
offset = addr - region->vaddr;
/* Access is allowed; handle it. */
if((r=map_pf(vmp, region, offset, wr)) != OK) {
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printf("VM: pagefault: SIGSEGV %d pagefault not handled\n", ep);
sys_sysctl_stacktrace(vmp->vm_endpoint);
if((s=sys_kill(vmp->vm_endpoint, SIGSEGV)) != OK)
vm_panic("sys_kill failed", s);
if((s=sys_vmctl(ep, VMCTL_CLEAR_PAGEFAULT, r)) != OK)
vm_panic("do_pagefaults: sys_vmctl failed", ep);
continue;
}
/* Pagefault is handled, so now reactivate the process. */
if((s=sys_vmctl(ep, VMCTL_CLEAR_PAGEFAULT, r)) != OK)
vm_panic("do_pagefaults: sys_vmctl failed", ep);
}
return;
}
/*===========================================================================*
* do_memory *
*===========================================================================*/
PUBLIC void do_memory(void)
{
int r, s;
endpoint_t who, requestor;
vir_bytes mem;
vir_bytes len;
int wrflag;
while((r=sys_vmctl_get_memreq(&who, &mem, &len, &wrflag, &requestor))
== OK) {
int p, r = OK;
struct vmproc *vmp;
if(vm_isokendpt(who, &p) != OK)
vm_panic("do_memory: endpoint wrong", who);
vmp = &vmproc[p];
r = handle_memory(vmp, mem, len, wrflag);
if(sys_vmctl(requestor, VMCTL_MEMREQ_REPLY, r) != OK)
vm_panic("do_memory: sys_vmctl failed", r);
}
}
int handle_memory(struct vmproc *vmp, vir_bytes mem, vir_bytes len, int wrflag)
{
struct vir_region *region;
vir_bytes o;
vir_bytes v;
/* Page-align memory and length. */
o = mem % VM_PAGE_SIZE;
mem -= o;
len += o;
o = len % VM_PAGE_SIZE;
if(o > 0) len += VM_PAGE_SIZE - o;
while(len > 0) {
int r;
if(!(region = map_lookup(vmp, mem))) {
map_printmap(vmp);
printf("VM: do_memory: memory doesn't exist\n");
r = EFAULT;
} else if(!(region->flags & VR_WRITABLE) && wrflag) {
printf("VM: do_memory: write to unwritable map\n");
r = EFAULT;
} else {
vir_bytes offset, sublen;
vm_assert(region->vaddr <= mem);
vm_assert(!(region->flags & VR_NOPF));
vm_assert(!(region->vaddr % VM_PAGE_SIZE));
offset = mem - region->vaddr;
sublen = len;
if(offset + sublen > region->length)
sublen = region->length - offset;
r = map_handle_memory(vmp, region, offset,
sublen, wrflag);
len -= sublen;
mem += sublen;
}
if(r != OK) {
printf("VM: memory range 0x%lx-0x%lx not available in %d\n",
arch_map2vir(vmp, mem), arch_map2vir(vmp, mem+len),
vmp->vm_endpoint);
return r;
}
}
return OK;
}