449ed17833
. if there is no memory there, it's not writable; this check bug by the shared memory's writable() method causes pagefaults not to be handled at all in certain situations, triggering an assert() in pt_writemap() . added some assert()s to catch this and similar situations in the future Change-Id: Ife89bfab4f9a3aa7bf4e33dfb0b13b89dcd5bb94
144 lines
3.3 KiB
C
144 lines
3.3 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(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->ph->phys == MAP_NONE)
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return 0;
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if(pr->parent->remaps > 0)
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return 1;
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return 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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