d343041caa
Introduce explicit abstractions for different mapping types, handling the instantiation, forking, pagefaults and freeing of anonymous memory, direct physical mappings, shared memory and physically contiguous anonymous memory as separate types, making region.c more generic. Also some other genericification like merging the 3 munmap cases into one. COW and SMAP safemap code is still implicit in region.c.
148 lines
3.4 KiB
C
148 lines
3.4 KiB
C
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/* This file implements the methods of anonymous memory.
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*
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* Anonymous memory is memory that is for private use to a process
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* and can not be related to a file (hence anonymous).
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*/
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#include <assert.h>
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#include "proto.h"
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#include "vm.h"
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#include "region.h"
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#include "glo.h"
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/* These functions are static so as to not pollute the
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* global namespace, and are accessed through their function
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* pointers.
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*/
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static int anon_reference(struct phys_region *pr);
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static int anon_unreference(struct phys_region *pr);
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static int anon_pagefault(struct vmproc *vmp, struct vir_region *region,
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struct phys_region *ph, int write);
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static int anon_sanitycheck(struct phys_region *pr, char *file, int line);
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static int anon_writable(struct phys_region *pr);
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static int anon_resize(struct vmproc *vmp, struct vir_region *vr, vir_bytes l);
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static u32_t anon_regionid(struct vir_region *region);
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static int anon_refcount(struct vir_region *vr);
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struct mem_type mem_type_anon = {
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.name = "anonymous memory",
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.ev_reference = anon_reference,
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.ev_unreference = anon_unreference,
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.ev_pagefault = anon_pagefault,
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.ev_resize = anon_resize,
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.ev_sanitycheck = anon_sanitycheck,
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.regionid = anon_regionid,
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.writable = anon_writable,
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.refcount = anon_refcount
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};
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static int anon_reference(struct phys_region *pr)
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{
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return OK;
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}
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static int anon_unreference(struct phys_region *pr)
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{
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assert(pr->ph->refcount == 0);
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if(pr->ph->phys != MAP_NONE)
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free_mem(ABS2CLICK(pr->ph->phys), 1);
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return OK;
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}
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static int anon_pagefault(struct vmproc *vmp, struct vir_region *region,
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struct phys_region *ph, int write)
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{
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phys_bytes new_page, new_page_cl;
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struct phys_block *pb;
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u32_t allocflags;
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allocflags = vrallocflags(region->flags);
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assert(ph->ph->refcount > 0);
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if((new_page_cl = alloc_mem(1, allocflags)) == NO_MEM)
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return ENOMEM;
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new_page = CLICK2ABS(new_page_cl);
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/* Totally new block? Create it. */
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if(ph->ph->phys == MAP_NONE) {
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ph->ph->phys = new_page;
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assert(ph->ph->phys != MAP_NONE);
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return OK;
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}
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if(ph->ph->refcount < 2 || !write) {
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printf("anon_pagefault: %d refcount, %d write - not handling pagefault\n",
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ph->ph->refcount, write);
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return OK;
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}
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assert(region->flags & VR_WRITABLE);
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if(ph->ph->share_flag != PBSH_COW) {
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printf("VM: write RO mapped pages.\n");
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free_mem(new_page_cl, 1);
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return EFAULT;
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}
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if(sys_abscopy(ph->ph->phys, new_page, VM_PAGE_SIZE) != OK) {
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panic("VM: abscopy failed\n");
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return EFAULT;
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}
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if(!(pb = pb_new(new_page))) {
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free_mem(new_page_cl, 1);
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return ENOMEM;
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}
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pb_unreferenced(region, ph, 0);
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pb_link(ph, pb, ph->offset, region);
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return OK;
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}
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static int anon_sanitycheck(struct phys_region *pr, char *file, int line)
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{
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MYASSERT(usedpages_add(pr->ph->phys, VM_PAGE_SIZE) == OK);
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return OK;
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}
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static int anon_writable(struct phys_region *pr)
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{
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assert(pr->ph->refcount > 0);
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if(pr->parent->remaps > 0)
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return 1;
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return pr->ph->phys != MAP_NONE && pr->ph->refcount == 1;
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}
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static int anon_resize(struct vmproc *vmp, struct vir_region *vr, vir_bytes l)
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{
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/* Shrinking not implemented; silently ignored.
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* (Which is ok for brk().)
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*/
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if(l <= vr->length)
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return OK;
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assert(vr);
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assert(vr->flags & VR_ANON);
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assert(!(l % VM_PAGE_SIZE));
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USE(vr, vr->length = l;);
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return OK;
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}
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static u32_t anon_regionid(struct vir_region *region)
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{
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return region->id;
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}
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static int anon_refcount(struct vir_region *vr)
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{
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return 1 + vr->remaps;
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}
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