minix3/servers/vm/mem_shared.c

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2020-02-21 00:59:27 +05:30
/* This file implements the methods of shared memory. */
#include <assert.h>
#include "proto.h"
#include "vm.h"
#include "region.h"
#include "glo.h"
/* These functions are static so as to not pollute the
* global namespace, and are accessed through their function
* pointers.
*/
static int shared_unreference(struct phys_region *pr);
static int shared_pagefault(struct vmproc *vmp, struct vir_region *region,
struct phys_region *ph, int write, vfs_callback_t cb, void *state,
int len, int *io);
static int shared_sanitycheck(struct phys_region *pr, const char *file, int line);
static int shared_writable(struct phys_region *pr);
static void shared_delete(struct vir_region *region);
static u32_t shared_regionid(struct vir_region *region);
static int shared_copy(struct vir_region *vr, struct vir_region *newvr);
static int shared_refcount(struct vir_region *vr);
static int shared_pt_flags(struct vir_region *vr);
struct mem_type mem_type_shared = {
.name = "shared memory",
.ev_copy = shared_copy,
.ev_unreference = shared_unreference,
.ev_pagefault = shared_pagefault,
.ev_sanitycheck = shared_sanitycheck,
.ev_delete = shared_delete,
.regionid = shared_regionid,
.refcount = shared_refcount,
.writable = shared_writable,
.pt_flags = shared_pt_flags,
};
static int shared_pt_flags(struct vir_region *vr){
#if defined(__arm__)
return ARM_VM_PTE_CACHED;
#else
return 0;
#endif
}
static int shared_unreference(struct phys_region *pr)
{
return mem_type_anon.ev_unreference(pr);
}
static int getsrc(struct vir_region *region,
struct vmproc **vmp, struct vir_region **r)
{
int srcproc;
if(region->def_memtype != &mem_type_shared) {
printf("shared region hasn't shared type but %s.\n",
region->def_memtype->name);
return EINVAL;
}
if(!region->param.shared.ep || !region->param.shared.vaddr) {
printf("shared region has not defined source region.\n");
util_stacktrace();
return EINVAL;
}
if(vm_isokendpt((endpoint_t) region->param.shared.ep, &srcproc) != OK) {
printf("VM: shared memory with missing source process.\n");
util_stacktrace();
return EINVAL;
}
*vmp = &vmproc[srcproc];
if(!(*r=map_lookup(*vmp, region->param.shared.vaddr, NULL))) {
printf("VM: shared memory with missing vaddr 0x%lx.\n",
region->param.shared.vaddr);
return EINVAL;
}
if((*r)->def_memtype != &mem_type_anon) {
printf("source region hasn't anon type but %s.\n",
(*r)->def_memtype->name);
return EINVAL;
}
if(region->param.shared.id != (*r)->id) {
printf("source region has no matching id\n");
return EINVAL;
}
return OK;
}
static u32_t shared_regionid(struct vir_region *vr)
{
struct vir_region *src_region;
struct vmproc *src_vmp;
if(getsrc(vr, &src_vmp, &src_region) != OK)
return 0;
return src_region->id;
}
static void shared_delete(struct vir_region *region)
{
struct vir_region *src_region;
struct vmproc *src_vmp;
if(getsrc(region, &src_vmp, &src_region) != OK)
return;
assert(src_region->remaps > 0);
src_region->remaps--;
}
static int shared_pagefault(struct vmproc *vmp, struct vir_region *region,
struct phys_region *ph, int write, vfs_callback_t cb,
void *state, int statelen, int *io)
{
struct vir_region *src_region;
struct vmproc *src_vmp;
struct phys_region *pr;
if(getsrc(region, &src_vmp, &src_region) != OK) {
return EINVAL;
}
if(ph->ph->phys != MAP_NONE) {
/* memory is there - pagefault does not need handling */
return OK;
}
pb_free(ph->ph);
if(!(pr = physblock_get(src_region, ph->offset))) {
int r;
if((r=map_pf(src_vmp, src_region, ph->offset, write,
NULL, NULL, 0, io)) != OK)
return r;
if(!(pr = physblock_get(src_region, ph->offset))) {
panic("missing region after pagefault handling");
}
}
pb_link(ph, pr->ph, ph->offset, region);
return OK;
}
static int shared_sanitycheck(struct phys_region *pr, const char *file, int line)
{
return OK;
}
static int shared_writable(struct phys_region *pr)
{
assert(pr->ph->refcount > 0);
return pr->ph->phys != MAP_NONE;
}
void shared_setsource(struct vir_region *vr, endpoint_t ep,
struct vir_region *src_vr)
{
struct vmproc *vmp;
struct vir_region *srcvr;
int id = src_vr->id;
vir_bytes vaddr = src_vr->vaddr;
assert(vr->def_memtype == &mem_type_shared);
if(!ep || !vaddr || !id) {
printf("VM: shared_setsource: zero ep/vaddr/id - ignoring\n");
return;
}
vr->param.shared.ep = ep;
vr->param.shared.vaddr = vaddr;
vr->param.shared.id = id;
if(getsrc(vr, &vmp, &srcvr) != OK)
panic("initial getsrc failed");
assert(srcvr == src_vr);
srcvr->remaps++;
}
static int shared_copy(struct vir_region *vr, struct vir_region *newvr)
{
struct vmproc *vmp;
struct vir_region *srcvr;
if(getsrc(vr, &vmp, &srcvr) != OK)
panic("copy: original getsrc failed");
shared_setsource(newvr, vr->param.shared.ep, srcvr);
return OK;
}
static int shared_refcount(struct vir_region *vr)
{
return 1 + vr->remaps;
}