minix/servers/vm/pagefaults.c
Ben Gras 49eb1f4806 vm: new secondary cache code
Primary purpose of change: to support the mmap implementation, VM must
know both (a) about some block metadata for FS cache blocks, i.e.
inode numbers and inode offsets where applicable; and (b) know about
*all* cache blocks, i.e.  also of the FS primary caches and not just
the blocks that spill into the secondary one. This changes the
interface and VM data structures.

This change is only for the interface (libminixfs) and VM data
structures; the filesystem code is unmodified, so although the
secondary cache will be used as normal, blocks will not be annotated
with inode information until the FS is modified to provide this
information. Until it is modified, mmap of files will fail gracefully
on such filesystems.

This is indicated to VFS/VM by returning ENOSYS for REQ_PEEK.

Change-Id: I1d2df6c485e6c5e89eb28d9055076cc02629594e
2013-04-24 10:18:16 +00:00

292 lines
7.1 KiB
C

#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 <assert.h>
#include "glo.h"
#include "proto.h"
#include "util.h"
#include "region.h"
/*===========================================================================*
* pf_errstr *
*===========================================================================*/
char *pf_errstr(u32_t err)
{
static char buf[100];
sprintf(buf, "err 0x%lx ", (long)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;
}
struct pf_state {
endpoint_t ep;
vir_bytes vaddr;
u32_t err;
};
struct hm_state {
endpoint_t requestor;
struct vmproc *vmp;
vir_bytes mem;
vir_bytes len;
int wrflag;
};
static void pf_cont(struct vmproc *vmp, message *m, void *arg, void *statearg);
static void hm_cont(struct vmproc *vmp, message *m, void *arg, void *statearg);
static void handle_pagefault(endpoint_t ep, vir_bytes addr, u32_t err, int retry)
{
struct vmproc *vmp;
int s, result;
struct vir_region *region;
vir_bytes offset;
int p, wr = PFERR_WRITE(err);
if(vm_isokendpt(ep, &p) != OK)
panic("handle_pagefault: endpoint wrong: %d", ep);
vmp = &vmproc[p];
assert(vmp->vm_flags & VMF_INUSE);
/* See if address is valid at all. */
if(!(region = map_lookup(vmp, addr, NULL))) {
if(PFERR_PROT(err)) {
printf("VM: pagefault: SIGSEGV %d protected addr 0x%lx; %s\n",
ep, addr, pf_errstr(err));
} else {
assert(PFERR_NOPAGE(err));
printf("VM: pagefault: SIGSEGV %d bad addr 0x%lx; %s\n",
ep, addr, pf_errstr(err));
sys_sysctl_stacktrace(ep);
}
if((s=sys_kill(vmp->vm_endpoint, SIGSEGV)) != OK)
panic("sys_kill failed: %d", s);
if((s=sys_vmctl(ep, VMCTL_CLEAR_PAGEFAULT, 0 /*unused*/)) != OK)
panic("do_pagefaults: sys_vmctl failed: %d", ep);
return;
}
/* If process was writing, see if it's writable. */
if(!(region->flags & VR_WRITABLE) && wr) {
printf("VM: pagefault: SIGSEGV %d ro map 0x%lx %s\n",
ep, addr, pf_errstr(err));
if((s=sys_kill(vmp->vm_endpoint, SIGSEGV)) != OK)
panic("sys_kill failed: %d", s);
if((s=sys_vmctl(ep, VMCTL_CLEAR_PAGEFAULT, 0 /*unused*/)) != OK)
panic("do_pagefaults: sys_vmctl failed: %d", ep);
return;
}
assert(addr >= region->vaddr);
offset = addr - region->vaddr;
/* Access is allowed; handle it. */
if(retry) {
result = map_pf(vmp, region, offset, wr, NULL, NULL, 0);
assert(result != SUSPEND);
} else {
struct pf_state state;
state.ep = ep;
state.vaddr = addr;
state.err = err;
result = map_pf(vmp, region, offset, wr, pf_cont,
&state, sizeof(state));
}
if(result == SUSPEND) {
return;
}
if(result != OK) {
printf("VM: pagefault: SIGSEGV %d pagefault not handled\n", ep);
if((s=sys_kill(ep, SIGSEGV)) != OK)
panic("sys_kill failed: %d", s);
if((s=sys_vmctl(ep, VMCTL_CLEAR_PAGEFAULT, 0 /*unused*/)) != OK)
panic("do_pagefaults: sys_vmctl failed: %d", ep);
return;
}
pt_clearmapcache();
/* Pagefault is handled, so now reactivate the process. */
if((s=sys_vmctl(ep, VMCTL_CLEAR_PAGEFAULT, 0 /*unused*/)) != OK)
panic("do_pagefaults: sys_vmctl failed: %d", ep);
}
static void pf_cont(struct vmproc *vmp, message *m,
void *arg, void *statearg)
{
struct pf_state *state = statearg;
handle_pagefault(state->ep, state->vaddr, state->err, 1);
}
static void hm_cont(struct vmproc *vmp, message *m,
void *arg, void *statearg)
{
int r;
struct hm_state *state = statearg;
printf("hm_cont: result %d\n", m->VMV_RESULT);
r = handle_memory(vmp, state->mem, state->len, state->wrflag,
hm_cont, &state, sizeof(state));
if(r == SUSPEND) {
printf("VM: hm_cont: damnit: hm_cont: more SUSPEND\n");
return;
}
printf("VM: hm_cont: ok, result %d, requestor %d\n", r, state->requestor);
if(sys_vmctl(state->requestor, VMCTL_MEMREQ_REPLY, r) != OK)
panic("hm_cont: sys_vmctl failed: %d", r);
printf("MEMREQ_REPLY sent\n");
}
/*===========================================================================*
* do_pagefaults *
*===========================================================================*/
void do_pagefaults(message *m)
{
handle_pagefault(m->m_source, m->VPF_ADDR, m->VPF_FLAGS, 0);
}
/*===========================================================================*
* do_memory *
*===========================================================================*/
void do_memory(void)
{
endpoint_t who, who_s, requestor;
vir_bytes mem, mem_s;
vir_bytes len;
int wrflag;
while(1) {
int p, r = OK;
struct vmproc *vmp;
r = sys_vmctl_get_memreq(&who, &mem, &len, &wrflag, &who_s,
&mem_s, &requestor);
switch(r) {
case VMPTYPE_CHECK:
{
struct hm_state state;
if(vm_isokendpt(who, &p) != OK)
panic("do_memory: bad endpoint: %d", who);
vmp = &vmproc[p];
state.vmp = vmp;
state.mem = mem;
state.len = len;
state.wrflag = wrflag;
state.requestor = requestor;
r = handle_memory(vmp, mem, len,
wrflag, hm_cont, &state, sizeof(state));
break;
}
default:
return;
}
if(r != SUSPEND) {
if(sys_vmctl(requestor, VMCTL_MEMREQ_REPLY, r) != OK)
panic("do_memory: sys_vmctl failed: %d", r);
}
}
}
int handle_memory(struct vmproc *vmp, vir_bytes mem, vir_bytes len, int wrflag,
vfs_callback_t callback, void *state, int statelen)
{
struct vir_region *region;
vir_bytes o;
struct hm_state *hmstate = (struct hm_state *) state;
/* 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, NULL))) {
#if VERBOSE
map_printmap(vmp);
printf("VM: do_memory: memory doesn't exist\n");
#endif
r = EFAULT;
} else if(!(region->flags & VR_WRITABLE) && wrflag) {
#if VERBOSE
printf("VM: do_memory: write to unwritable map\n");
#endif
r = EFAULT;
} else {
vir_bytes offset, sublen;
assert(region->vaddr <= mem);
assert(!(region->vaddr % VM_PAGE_SIZE));
offset = mem - region->vaddr;
sublen = len;
if(offset + sublen > region->length)
sublen = region->length - offset;
if(hmstate && hmstate->requestor == VFS_PROC_NR
&& region->def_memtype == &mem_type_mappedfile) {
r = map_handle_memory(vmp, region, offset,
sublen, wrflag, NULL, NULL, 0);
} else {
r = map_handle_memory(vmp, region, offset,
sublen, wrflag, callback, state, sizeof(*state));
}
len -= sublen;
mem += sublen;
}
if(r != OK) {
#if VERBOSE
printf("VM: memory range 0x%lx-0x%lx not available in %d\n",
mem, mem+len, vmp->vm_endpoint);
#endif
return r;
}
}
return OK;
}